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CERN/LHCC-2013-012

LHCC-114

12 June 2013

LARGE HADRON COLLIDER COMMITTEE

Minutes of the one-hundredth-and-fourteenth meeting held on

Wednesday and Thursday, 12-13 June 2013

OPEN SESSION - Status Reports

1. LHC Machine Status Report: Katy Foraz

2. LHCb Status Report: Niels Tuning

3. ALICE Status Report: Dhevan Raja Gangadharan

4. ATLAS Status Report: Ludovico Pontecorvo

5. CMS Status Report: Jeff Berryhill

6. TOTEM Status Report: Mirko Berretti

7. LHCf Status Report: Takashi Sako

8. MoEDAL Status Report: James Pinfold

9. RD39 Status Report: Jasu Haerkoenen

10. RD42 Status Report: William Trischuk

11. RD50 Status Report: Gianluigi Casse, Michael Moll

12. RD51 Status Report: Leszek Ropelewski

13. Letter of Intent ‘Development of Pixel Read-out Integrated Circuits for Extreme Rate & Radiation’: Jorgen Christiansen

14. Letter of Intent ‘3D Sensor & Micro-fabricated Detector Systems’: Cinzia Da Via

CLOSED SESSION:

Present: U. Bassler, S. Bertolucci, P. Bloch, A. Boehnlein, J.-C. Brient, H. Burkhardt, P. Burrows, C. Cecchi, M. Demarteau, D. Denisov, C. Diaconu, G. Eigen, E. Elsen (Chairman), D. D’Enterria, G. Giudice, B. Gorini, E. Meschi, S. Miscetti, T. Mori, B. Panzer-Steindel, R. Roser, E. Tsesmelis (Scientific Secretary), T. Ullrich, H. Wilkens

Apologies: R.-D. Heuer, A.-L. Perrot

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1. PROCEDURE

The minutes of the one-hundredth-and-thirteenth LHCC meeting (LHCC 2013-004 / LHCC 113) were approved.

The Chairman thanked the outgoing Test Beam Coordinator, H. Breuker, and welcomed the new Test Beam Coordinator H. Wilkens (Physics Department) to the Committee.

2. REPORT FROM THE DIRECTOR FOR RESEARCH AND COMPUTING

The Director for Research and Computing reported on issues related to the LHC. He reported on deliberations of the LHC experiments’ Resources Review Boards (RRBs). The RRBs have commenced dedicated deliberations on the upgrades of the LHC experiments. A report providing an overview of the upgrades of the LHC experiments is planned to be given at the October 2013 sessions of the RRBs. Moreover, as was the case for the LHC experiment construction phase with the implementation of the COst REview (CORE) group, a similar dedicated group will be created jointly between the LHCC and the Scrutiny Group (SG) of the RRBs. The newly-created Upgrade Cost Group (UCG) will review all upgrade-related costs planned and incurred by the LHC experiments for their upgrade projects for the period after the Long Shutdown 1 (LS1). The UCG will review project costs at the time of submission of a draft Technical Design Report (TDR) to the LHCC. The outcome of each cost review will be submitted in a written report, together with the findings of the LHCC as regards scientific and technical issues, to the Research Board (RB) for the formal consideration and decision on approval of the TDR. Finally, the LHCC is considering implementing annual comprehensive reviews of each experiment that will review across all aspects and activities.

3. REPORT FROM THE LHC PROGRAMME CO-ORDINATORS

The LHCC heard a report from the LHC Programme Co-ordinators, concentrating on plans regarding Run II for LHC operations as of 2015, i.e. following the Long Shutdown 1 (LS1). The plans of ALICE for Run II include running in Pb-Pb collision mode (to reach the target of 1 nb-1 of accumulated data); proton-proton collision data (to provide a reference sample for the 1 nb-1 Pb-Pb data); and proton-Pb collision data (to enlarge the data sample collected in 2013). In particular, ALICE operation in proton-proton mode with a luminosity of between 1-2 × 1029 cm-2 s-1 and 25 ns bunch spacing needs further studies prior to implementation. Moreover, LHCf is preparing for Run II. LHCf requests a one-week dedicated run in proton-proton collision mode at 13 TeV centre-of-mass energy.

4. REPORT & DISCUSSION WITH LHC EXPERIMENT UPGRADE REFEREES

The LHCC heard a report from the LHC experiment upgrade referees, concentrating on the LHC 10-year plan and the upgrade plans of CMS, ATLAS, and ALICE.

The referees reported on the CMS Level-1 Trigger Upgrade for Phase 1 (CERN-LHCC-2013-011). The motivation for the upgrade to the Level-1 Trigger system is to maintain physics acceptance within 100 kHz and preserve excellent performance for searches, precision Higgs studies and heavy-ion physics during higher luminosity running expected after the Long Shutdown 1 (LS1). The Technical Design Report (TDR) outlines projected trigger rates and

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representative physics studies to demonstrate the need for the upgrade and describes the technical specifications. The trigger will use the μTCA Telecoms standard and it relies heavily on state-of-the-art Field Programmable Gate Arrays (FPGAs) with high capacity optical serial links, which allows for great algorithmic flexibility.

With a detailed simulation of a representative trigger menu, the extended capabilities of the trigger upgrade have been well motivated and meet the needs of the experiment after Long Shutdown 2 (LS2). The trigger upgrade calls for splitting the signals from the hadronic calorimeter and duplicating the optical signals from the electromagnetic calorimeter. This provides access to the full calorimeter granularity at the trigger level. As for the muon trigger, the information from the currently three muon detection systems is combined to provide one higher resolution muon trigger. At a later stage the input from the calorimeter triggers can be applied to identify isolated muon candidates. Improvements to the global trigger will remove the current limit on 128 algorithms and will enable the implementation of more sophisticated trigger variables, such as invariant masses. Significantly increased logic resources will be available under the new architecture.

This upgrade is evolutionary, that is, it will be implemented incrementally starting in LS1 and continuing until LS2. While new elements of the trigger are being installed, the complete functionality of the existing trigger will be retained and the new system can be commissioned in parallel to running the existing trigger. This should allow for ample feedback for successful implementation. The upgrade will also reduce the number of boards and consolidate their variety and will position the hardware well for future technological improvements.

The ATLAS Collaboration presented the Technical Design Report (TDR) for the upgrade of the Muon Small Wheel detector for Phase 1 (CERN-LHCC-2013-006). The pseudorapidity range η = 1.3 – 2.0 is currently covered by 8 layers of Monitored Drift Tubes (MDTs) and two layers of Thin Gap Chambers (TGCs); four layers of Cathode Strip Chambers (CSCs) cover the range η = 2.0 – 2.7. This ensemble of detectors constitutes the Muon Small Wheel, which is anticipated to see a significant deterioration of the single hit efficiency for the MDTs due to the large background rate. Moreover, the fake hit rate is nearly an order of magnitude larger in the end-cap compared to the barrel because the present Level-1 trigger primitive in the end-cap is based only on the segments in the station after the toroid. The muon trigger efficiency is significantly affected, which adversely impacts the physics reach. The Collaboration proposes to replace the Muon Small Wheels with a new four stack detector (New Small Wheels, NSW) composed of two 4-layer MicroMegas (MM) detectors sandwiched between 4-layer TGCs for a total of 16 detection planes, which meet the strict design criteria of providing high quality interaction point pointing segments in the NSW, on-line segment reconstruction every 25 ns with an angular resolution < 1 mrad and with a rate capability up to 15 kHz/cm2 and good pT resolution. Common readout for both the MM and TGCs is foreseen, with each set of detectors providing independent trigger information. The muon trigger fake rate is expected to be reduced by at least an order of magnitude. All components are in prototyping stage with no major technical problems. The mass production of large-area MM foils is expected to be carried out by industry. The schedule calls for full-scale production to start in 2015 with project completion late 2016 at a cost of 11.4 MCHF.

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The ATLAS experiment also presented the Technical Design Report for the Fast Track Trigger (FTK), which is a system of custom electronics that does global track reconstruction in the pixel and silicon strip detectors after every Level-1 trigger, that is, at 100 kHz (CERN-LHCC-2013-007). By adding the FTK to the current trigger architecture, the experiment is able to retain its physics capabilities within the 100 kHz Level-1 trigger bandwidth. The rapid pattern recognition and track fitting allows global track reconstruction of all tracks with pT > 1 GeV/c to be done in <100 µs, thus providing the tracks at the beginning of Level-2 event processing. This will enable at the trigger level event selection based on the presence of heavy quarks and τ-leptons, lepton isolation, vertex association and more. The performance of the FTK has been extensively simulated with Monte Carlo data samples with pile-up of 46 and 69 events and has been compared to Level-2 tracking, offline tracking, and Monte Carlo truth information. The simulated performance of the FTK is impressive and near equal to offline reconstruction in most parameters for single particle and full event reconstruction. The pattern recognition uses content addressable memory (CAM) custom chips, which currently store 109 patterns. With this architecture all patterns see each hit almost simultaneously. The pattern generation needs careful attention, since very narrow patterns lead to more patterns than can be stored; wide patterns lead to many track candidates with unrelated hits. Variable resolution patterns have been implemented which allow different widths in each layer in each pattern providing more flexibility for the pattern generation. The FTK architecture is based on massive data parallelism. A system of 16 000 custom associated memory (AM) chips, each holding 128 000 patterns, are needed. All silicon hits, from both the pixel and strip detector, are transferred to the FTK at each bunch crossing. At the centre of the FTK read-out resides the auxiliary boards, each of which has a data transfer capacity of 48 Gb/s. All boards are in the prototyping stage and the design of the AM05 chip, which holds fewer patterns than the final design, is being completed. Submission of the production AM06 chip is foreseen for spring of 2014. The installation and commissioning is evolutionary with schedule as contingency. Installation of a system to cover the barrel region for a pile-up of 46 is foreseen by July 2015; coverage of the entire detector for pile-up of 46 is planned for the end of 2015 with full installation for Phase 1 pile-up by the end of 2018. The estimated cost is 3.9 MCHF.

The ALICE Collaboration presented a draft Letter of Intent to add a silicon pixel tracking system, the Muon Forward Tracker (MFT), to the forward muon tracking system in the high pseudo-rapidity region. The proposed detector is designed to detect muons in the polar angular range of between 2 – 9 degrees, i.e. – 4.0 < η < – 2.5, over the full azimuthal range. The detector consists of 5 or 6 planes of monolithic active pixel detectors. The sensors employed are the same sensors as will be used in the Inner Tracking System (ITS) with a total area of 2.7 m2. This new detector would provide good pointing resolution for the identification of single muons from D- and B- mesons and discrimination between prompt and displaced di-muons. It would also improve the invariant mass resolution at low mass and improve the background rejection. The MFT will enhance the physics capabilities of the experiment leading to a better understanding of the hot nuclear matter due to the restoration of the chiral symmetry. Further studies to explore the enhanced capability for proton-proton, proton-Pb and Pb-Pb collisions and support for the choice of technology and detector design

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are being undertaken. ALICE plans to submit the corresponding Letter of Intent to the next LHCC session.

5. DISCUSSION WITH ATLAS

Introduction

The ATLAS Collaboration continues to be very productive in analysing its full 25 fb-1 data set. It is also in a two-year shutdown in which significant consolidation work is being done as well as the installation of the Insertable B-Layer (IBL), a new inner layer of silicon, and is also finalising the technical details of its Phase 1 upgrades and performing R&D and defining its needs for its Phase 2 upgrades. That is a tremendous amount to juggle for a Collaboration of any size. ATLAS is handling all of these responsibilities very well, and is to be congratulated for these achievements.

Physics

To date, ATLAS has published 249 papers on its collision data. Fifty-five conference notes have been written thus far this year, almost at the identical pace to last year at this time. ATLAS has shown a variety of updated physics results, from the newly-released Higgs properties to a top mass with a total uncertainty of just over 1 GeV. Thirteen new SUSY analyses utilising the complete data set at 8 TeV centre-of-mass energy have been completed thus far and no signs of new physics have been observed. The Collaboration is targeting the European Physical Society conference in Stockholm in late July 2013 as its primary target new physics results, although emphasis is shifting to delivering the final papers on Run I (2010-2012) data.

Long Shutdown 1

The two-year LHC Long Shutdown 1 (LS1) has commenced. ATLAS has a long list of projects that it wants to accomplish during this short period of time. Since the previous LHCC session in March 2013, the ATLAS Pixel group has removed its detector from the collision hall and brought it to the surface in order to replace the Service Quarter Panels (SQPs) and to prepare the detector for the insertion of the IBL and beam pipe. The removal of the detector went very smoothly and was well planned, with both the cabling and the cooling line disassembly having proceeded well. The current SQPs have been removed and the new ones are ready to be installed. The team is waiting for the arrival of the new diamond beam monitor detectors that get mounted on the SQPs and then installed on the detector. The original beam pipe has been removed and the new inner support tube (IST) will be installed in two weeks. This installation would have been the more difficult if done downstairs but is greatly simplified on the surface. The Pixel detector will be re-installed in January 2014 as per the plan.

The IBL continues to make good progress and is holding to its aggressive schedule. The bump bonding continues to go well with now 9 of the 12 batches of sensors complete. Flex circuits are now being attached and tested. The mechanical assembly of sensors onto Staves has begun. Three of the required 14 staves are complete and the remaining 11 should be done by late August 2013. The staves will be mounted to the beam pipe (through a carbon fibre shell),

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the services and cabling are done and final testing is going on. The IBL must be installed into the Pixel detector by April 2014 so that ATLAS remains on its overall schedule.

The Transition Radiation Tracker (TRT) situation is perhaps the most worrisome. Leaks formed in the latter part of the 2013 run have now been examined and attributed to a combination of brittleness from radiation and strain on the pipes. Most of the leaks are found close to the Swagelok fittings. On the end plug most of the breaks are accessible and they are being repaired and new sections of piping are being installed. There is no access to the broken lines in the barrel and thus the Collaboration will continue running in this current state. The detector has sufficient manifolds to isolate a leaky line and shift its gas flow from expensive Xe to a much cheaper Ar-CO2. The tracking performance will be fine for those lines that have been switched but the missing transition radiation information will affect particle identification.

The power supplies for both the Liquid Argon and Tile Calorimeter are being replaced and that effort is going well. Leak checking of the Monitored Drift Tube (MDT) detector and Resistive Plate Chambers (RPCs) is in progress and a few leaks have been identified and will be repaired.

Overall, the shutdown is going very well. Most activities are on schedule or a bit ahead of schedule and no significant obstacles have been encountered thus far.

Software and Computing

The software and computing effort is also very busy and has significant work ahead of itself as well. The offline team has completed the processing of both the B physics and Hadron Physics delayed trigger streams. The 2.76 GeV centre-of-mass data has been reprocessed with the latest software release. The new Russian Tier-1 computing centre is now working well and it was used for the above processing.

Preparations for Run II are going on within the software and computing teams. ATLAS is working to speed up the algorithms and utilise modern CPUs more fully. The group is implementing event-level and algorithm-level parallelism, and optimising data formats for physics analysis. The Collaboration is changing its analysis model. The Analysis Object Data (AOD, reconstruction data) is being updated and made ROOT-readable. A faster data reduction framework is being implemented and a consistent offline framework that is well integrated into the ATLAS distributed computing model is under development. With all these changes ATLAS should have a much faster and streamlined code and have fewer copies of the data around, thus able to handle a higher trigger rate in real time than what is capable today still within a constant budget.

Upgrades

The LHCC was presented with two Phase 1 Technical Design Reports (TDRs) just prior to the meeting. One TDR covers the Fast TracKer (FTK) trigger upgrade (CERN-LHCC-2013-007) while the other one covers the muon small wheel detector (CERN-LHCC-2013-006). Both proposals are at a very advanced stage. Significant prototyping has taken place and the details presented in the report represent the confidence that these two upgrades will be executed well. The physics motivation for both is very well articulated – in both cases these upgrades will

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provide the Collaboration access to physics that it would otherwise not have at the high luminosity and pile-up. These two TDRs are both about maintaining capability and also improving it. The FTK is potentially so powerful that the referees consider that the ATLAS Collaboration has not yet figured out all of the ways to exploit it. The plan is to implement the FTK with full η coverage in 2016. Key to its success is the custom-made associative memory chip, which altogether will hold about 1 billion patterns and which are to be examined at an event rate of up to 100 kHz. The LHCC’s only point of pause for these two upgrades has to do with how one scales the FTK technology to Phase 2, where perhaps more than 10 billion patterns would need to be stored. However, on this timescale ATLAS plans to build a new tracking detector and to modify the triggering scheme and latencies. FTK-type technologies may be usable at Phase-2, but a rebuild is likely to be required. The muon small wheels will have added segmentation and trigger capability that will enhance ATLAS physics capability in the forward regions at the higher expected energies and luminosities. The LHCC will go through the details of the proposals with ATLAS Management in the coming weeks. It is expected that the LHCC will be able to fully endorse both TDRs at its session in September 2013.

6. DISCUSSION WITH LHCb

Physics

The LHCC congratulates the LHCb Collaboration for their high-quality scientific results. The Collaboration has reached 124 articles in press with a production pace of 24 articles per three-month period. The physics highlights for this last period were the observation of CP violation in Bs decays and an improved measurement of the CKM γ angle. For the channel Bs → K π the LHCb Collaboration was able to make a 5σ observation of CP violation by determining the asymmetry Acp(B0

s → K- π+) = 0.27 ± 0.04(stat.) ± 0.01(syst.). The B0s

therefore joins the small group of CP violating particles such as K0, B0 and B+. The update of the GGSZ analysis (B → DK with D → Ks h+h-) with 2012 data (2 fb-1) and the combination with other results obtained with 2011 data only (1 fb-1) allowed the LHCb Collaboration to extract a value for γ of (67±12)°. This is a factor of ~ √2 better than previous measurements, while leaving room for further improvements. Many new results were presented in the LHCC Open Session and many others (~ 30) are in the pipeline. Most of the analyses are aiming at the European Physical Society Conference in July 2013 and will be based on fully re-processed data. A small fraction of the analyses will still use 2011 data only, the reason being the availability of Monte Carlo samples that have not yet been completed for all samples. A first release of the “Upgrade physics and Trigger document” will be available for the VELO technology choice in June 2013. This document uses four selected physics channels as a baseline for the comparison of alternatives. It will also serve as supporting documentation for the upgrade reviews.

Long Shutdown 1

The LHCb experiment has been operated since 2008 without any major intervention and the Long Shutdown 1 (LS1) is being used to consolidate the infrastructure and the detector. The most relevant consolidation of infrastructure concerns the Uninterrupted Power Supply (UPS) system that has been fully renewed and improved: 13.5 t of hardware with double redundancy

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were deployed for the online-servers’ room at the surface, the online room in UX85 and the magnet control. The online network has also been improved by adding a redundancy for the power and cooling systems together with a full re-cabling of the network. The online servers and disks have been strengthened by increasing the available storage. The replacement of the Beryllium beam pipe of Section 3 and the upgrade of its support structure have also been completed. This operation consisted of a long series of interventions such as the removal of beam pipe Sections 2 and 4, the opening of all large detectors and muon filters, the installation of protection for the beam pipe in Section 1 and a continuous survey before, during and after the installation. After three months operation, the beam pipe of Section 3 has been moved out without accident and Section 1 has been closed and made vacuum tight. This was obtained by means of much preparation and planning and the operation has been completed with only two weeks delay with respect to schedule.

Another long list of consolidation items is planned to be completed within one year, highlights for the summer being the consolidation of the Inner Tracker (IT) and Outer Tracker (OT) primary cooling systems and the preparation of additional shielding behind the M5 muon stations. The goal is to maintain the tight schedule to complete all these work packages in order to allow for the commissioning weeks. During these commissioning weeks, the full detector will be turned on and read out to check overall functionality, to exercise the crew and in general to sustain and improve the expertise. The LHCC took note the careful planning and preparation for the consolidation items and the high quality of work done so far.

For the detectors, the most relevant item was to understand further the status of the radiation hardness of the OT system. Before LHC running, a 20% signal loss after 20 hours of irradiation had been observed. This loss was attributed to the presence of a plastifier inside the used glue (AY103-1). During running, and after 2010, the addition of 1.5% of O2 in the counting gas prevented the ageing downstream of the gas direction flow. In situ tests, done with source and threshold scans, showed the gain loss remained below 10%. During the present shutdown period, a Sr90 irradiation test was carried out, for a total of 475 hours, and resulted in no visible gain loss. This measurement confirmed the in situ indications that the OT has become more radiation resistant. There is not yet a full understanding of this behaviour, and experts continue studying the problem.

Upgrades

The upgrade of the LHCb experiment follows the foreseen pace of the official road-map. The milestone profile shows that out of a total of 22 milestones expected, 20 milestones have already been reached, while one was in progress at the time of the LHCC session. The status of the funding profile from agencies has been presented at the Resources Review Board (RRB) session of April 2013, confirming that positive feedback has been received for at least 70% of the requested funds, including the proposed share of the Common Funds. The detailed cost sharing among institutions will be better defined once sub-system Technical Design Reports (TDRs) will be completed together with compilation of the construction Memoranda of Understanding. The next major steps are the decisions of technologies for the Vertex Locator (VELO), Central Tracker and Ring Imaging Cherenkov (RICH) detectors and the completion of most of the TDRs for next autumn 2013.

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The upgrade discussion at this LHCC session focused on two items that were not previously addressed: the calorimeter and the muon system.

The calorimeter upgrade scope is that of keeping all calorimeter modules unchanged, reducing the photomultiplier tube gain by a factor of five while improving the amplification stage without adding noise. Removal of the Scintillating Pad Detector (SPD) and Preshower (PS) systems is planned. Upgrade of the read-out electronics is necessary. The calorimeter group showed in detail the test of radiation resistance for all components, the effect of pile-up on the resolution and the status of electronics upgrade.

The radiation hardness was studied in two different ways. Two Electromagnetic Calorimeter (ECAL) modules, of the inner type, were installed in the LHC tunnel and their performance tested with a Cs137 source. The last measurement in April 2013, corresponding to a 3.4 fb-1 sample, demonstrated a response degradation of ~ 50%. This effect in resolution is moderate, suggesting that modules could sustain up to 20 fb-1. One module was instead irradiated with 24 GeV protons at the CERN Proton Synchrotron irradiation facility. An irradiation of 2 MRad, equivalent to 16 fb-1, resulted in a light loss of a factor five corresponding to an energy resolution of 2% at 50 GeV that is still acceptable. Other components (bases and PMTs) appear to be less critically dependent on radiation.

The effect of pile-up on the resolution was tested by simulation, suggesting that at low energy (~ 400 MeV) and at a luminosity of 1033 cm-2 s-1 it will be the dominant term worsening the resolution from 7% to 14%. The pile-up distribution is uniform on the detector while the cell size increases with the distance from the beam. A modified clustering algorithm looks capable of reducing the pile-up effect in the outer region while not performing well in the inner region due to the comparable size of calorimeter cell and the Moliere radius.

For the electronics, the compensation of the lowered PMT gain will be done by means of an amplifier; both ASIC and discrete prototypes exist and are under test. For the read-out, a new digital section is being designed based on the GBT link chip with 4 DAQ links and one Low-Level Trigger (LLT) link per board. Implementation of a trigger board based on TELL40 is also underway.

The muon upgrade has been divided in two phases. The first phase is to make the electronics compliant with 40 MHz read-out by the end of Long Shutdown 2 (LS2). Apart from the removal of the highest occupancy station, M1, it consists in a renewal of the front-end electronics system that does not imply any detector hardware changes. The Phase 2 upgrade aims instead of installing new high read-out granularity detectors in the hottest occupancy regions. The plan is to have R&D completed for LS2 and be ready to install for Long Shutdown 3 (LS3). Details are still under discussion.

So far, the muon detector has operated very well with high performance and a negligible sign of ageing (dead channel fraction < 10-4). This upgrade is motivated by the fact that the read-out electronics is ten years old and it will be complicated to guarantee its full functionality, fifteen years from now, together with being compatible with the new read-out systems. Vintage examples are the CanBus, the LHCb clock distribution and the Level-0 trigger. No changes will occur on the front-end located on the muon chambers (Carioca chips and

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interface boards). In the off-detector electronics, the intermediate boards will be kept unchanged while a renewal of the synchronisation boards (nODE), service (nSB) and pulse distribution modules (nPDM) will occur. CanBus will be substituted by ECS via a duplex GBT. A new optical distribution system with 280 GBT links will grant the transfer rate for the new Level-0 muon trigger and for the TDC read-out, each constituted by four Tell40 boards. The muon system upgrade plans have been presented in June 2013 to the INFN CSN1 Committee, where it was well received and the LHCb Collaboration was asked to proceed. Presentation of an upgrade document for the Russian funding agency is also underway. The major milestone is to have the TDR ready for January 2014.

The high-luminosity tests carried out in December 2012 suggested that the innermost regions of stations M2 and M3 will work at the beginning of the upgrade phase but that the Multi-Wire Proportional Chamber (MWPC) ageing will not be tolerable in LS3 (expected charge on the wire of 0.5 C/m). These findings motivated the discussion for a Phase 2 muon upgrade. An R&D has to be carried out to find a viable solution. Proposed choices so far are triple-GEM (Gas Electron Multiplier) detectors or high- granularity cathode pad MWPC.

7. DISCUSSION WITH ALICE

Introduction

The LHCC recognises that the ALICE Collaboration has made excellent progress during the on-going long shutdown and continues to provide exciting physics results. The Committee congratulates the ALICE Collaboration on these achievements.

Physics

ALICE is in the midst of an intense period of analysis harvesting the dataset recorded during the proton-Pb run in spring 2013. ALICE has 66 papers published or submitted. Since the last LHCC session in March 2013, five new papers on results from Pb-Pb and proton-proton collisions were submitted and four have been published.

Long Shutdown 1

ALICE is well on track with their Long Shutdown 1 (LS1) schedule. The dry assembly of the installation support structure for the Dijet Calorimeter (DCAL) including the test insertion of one supermodel (plus one Photon Spectrometer (PHOS) module) was completed. The installation of the new Uninterrupted Power Supply (UPS) system shows good progress and new switchboards are being installed and cabled up. The system is expected to be operational in September 2013. Three new, more powerful, water chillers are being installed in the SU2 building and the heat exchangers were replaced. Two more chillers will follow in 2014 providing spare capacity thus eliminating the high risk of interruption of operation in case of failure during run time. Various consolidation efforts are underway. Repairs of the muon tracking chamber are on-going (Station 3 is already repaired, while work for Stations 4 and 5 are on-going), the Argon dewar was sent to the manufacturer for a complete refurbishment, and the Transition Radiation Detector (TRD) and Time Projection Chamber (TPC) low-voltage cables that broke under their own weight are re-routed and new support structures are installed. A dedicated Consolidation Task Force was formed to manage many smaller repair and maintenance efforts. The production of the remaining five TRD super modules is

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underway with a new manufacturer now producing the read-out boards. Although advancing well, the production of the models needs to be monitored carefully. The three missing modules situated at the bottom of the barrel need to be installed during LS1, while the two on the top could be installed during an annual Technical Stop, if delayed.

ALICE plans to upgrade the TPC read-out system during LS1 in order to improve the read-out speed by a factor of ~2 and to provide higher operation stability. The upgrade includes the building of a new Readout Control Unit, RCU2, enabling the subdivision of read-out branches (from two to four) and providing increased link speed (~5 Gb/s). Radiation issues are mitigated by using single radiation tolerant FPGAs. The aggressive time plan envisions the finalisation of the design by April 2014, mass production of the chips to be done by June/July 2014, and installation starting in September 2014. This upgrade would be especially beneficial for running-in rare trigger mode reducing the dead time substantially.

To further improve operational stability (reduce trips) ALICE is considering changing the TPC gas mix from Ne-CO2 to Ar-CO2. While the increased primary ionisation allows reducing the gas gain, Ar does increase multiple scattering and increases the space charge substantially, thus leading to larger distortions. As a consequence, the gating grid closing time would have to be increased from 300 μs to 500 μs. With the new TPC read-out, the dead time fraction for central events trigger at 400 Hz would increase from 12% with the current gas mixture to 22% for Ar-CO2.

Upgrades

The LHCC congratulates the ALICE Collaboration for the continuing excellent progress on the design and R&D of the new Inner Tracker System (ITS). ALICE plans to continue R&D until the end of 2013 in order to further improve signal-to-noise ratios, to study in detail various front-end circuit and read-out architectures, and to optimise the lay-out for high yield and stitching. In the CERN PS test beam, detection efficiency measurements with the Explorer chip were carried out showing excellent results. The fake hit rate fraction, estimated from laboratory noise measurements, can be kept at the 10-9 level, while maintaining an excellent efficiency of > 99% at the highest bias voltage. Test beam studies at DESY using the EUDET telescope were conducted to study the performance of irradiated sensor samples (Explorer chip) and to verify the Monte Carlo model for inclined tracks (MIMOSA32). The irradiated sample (1013 neq) showed up an increase of up to 15% in noise level with little to no deterioration of the signal. Laser soldering tests of 50 μm thick silicon dummy chips and polyimide foils showed no visible damages but slight gas enclosures were visible in some samples. Subsequent tests with reduced soldering temperature are expected to improve the results. Prototype testing of a chip embedded into polyimide metal cables is in progress at the CERN PCB workshop, with metrology measurements being conducted at each production step. Copper-based prototype flex for the inner layers are complete and are being prepared for laser soldering tests (hole diameter 200 μm), while alternative aluminium-based flex are in production. Inner and outer barrel stave prototypes are being examined. The material budget for the inner layers has improved showing an average radiation length of ~ 0.28%.

The main objective of the current R&D efforts on the TPC upgrade is the control of the Ion Back Flow (IBF) of the Gas Electron Multiplier (GEM) system. The goal defined in the Letter

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of Intent was 0.25-0.5% IBF at a gain of 2000, resulting in ε = 5-10 back flowing ions per primary ionisation. This goal has not yet been achieved with a standard triple-GEM system. The best result so far is 3% IBF at a gain of 1000. ALICE is now considering ε = 10 as the TDR baseline scenario and plans to press forward with large-pitch GEMs where a 1% IBF should be achievable after optimisation. The current plan is to decrease the gas gain to 1000. This can be achieved by increasing the IROC pad size by 60% and decreasing the noise level in the new read-out electronics by 25%. Studies of the TPC gas mixtures show that with a Ne-CO2 mix, distortions at ε = 10 are tolerable, while Ar-based mixtures are excluded. Further studies, e.g. of CF4 mixtures are underway. In parallel, tests of a first large prototype and related R&D are in progress.

The development of a common front-end chip interfacing the detector front ends to the DAQ for the TPC and the muon tracking system has started. The TSMC technology is the likely choice; CERN will support TSMC 65 nm and 130 nm from the end of the year.

Online-Offline (O2) upgrades are essential for ALICE running in Phase 2. The data-taking rate upgrades will allow the experiment to sample the full 50 kHz Pb-Pb interaction rate resulting in a ~1.1 TByte/s read-out rate. In order to reduce this to a manageable 20 GByte/s rate to mass storage, means of massive data volume reduction have to be found. ALICE aims to achieve this by (partial) online reconstruction and by discarding the referring raw data. ALICE is already following this path by only recording the online reconstructed TPC clusters since the 2011 Pb-Pb run. For Phase 2 the upgrade includes a newly-developed online tracking that will allow ALICE to discard also (at least in large parts) the hits/clusters and store only track or track segments. Most crucial in this context is the calibration that has to be incorporated in the online tracking. Especially the luminosity dependent TPC space charge effects and resulting distortions have to be well understood before deploying this system. The project is well organised. Eleven Computing Working Groups have been formed consisting of ~50 members from 10 involved institutions. The required computing hardware architecture is in large parts designed and development of the algorithms is in progress.

The ALICE Collaboration intends to submit to the September 2013 or December 2013 sessions of the LHCC the TDRs for the TPC, ITS, and electronics upgrades. The Muon Forward Tracker (MFT) Letter of Intent Addendum will be submitted to the September 2013 LHCC session.

Run II Plans

In order to address scheduling and machine issues early, ALICE developed a first draft of the Run II plan. The goal in Pb-Pb is to record 1 nb-1 and to increase the central and unbiased event data sample substantially by a factor three and ten, respectively. Pb-Pb runs are envisioned in 2015 and 2016 (with a levelled instantaneous luminosity of 1027 cm-2 s-1). ALICE plans to record a matching proton-proton reference sample in 2015-2017 (60 pb-1) and envisions a second long proton-Pb run in 2017.

For the 2015 proton-proton running period, ALICE intends to run a pure minimum bias trigger at a luminosity of 1-2 × 1029 cm-2 s-1. Running at this low luminosity requires close coordination with the LHC machine since a substantial displacement of the beams will be

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required. Discussions with machine experts are underway. The LHCC supports the plan presented provided that the minimum bias proton-proton running can be realised.

The ALICE Collaboration is opposing the idea of combining heavy-ion runs in the Run II period because (i) of the high risk of hardware failure that could jeopardise the whole programme, (ii) the enormous stretch to computing resources, and (iii) the substantially uneven load the Collaboration would have to face. The LHCC shares ALICE’s concerns and suggests avoiding any clustering of heavy-ion runs if possible.

8. DISCUSSION WITH CMS

General

CMS is pursuing an aggressive agenda in multiple areas: the physics harvest from Run I, the Long Shutdown 1 (LS1) consolidations and upgrades, preparations for Run II, developing and executing the Phase 1 upgrades and preparing for the Phase 2 upgrades. The LHCC congratulates the CMS Collaboration for handling all these challenges very well.

Physics

The first area of activity is the analysis of the full 2011-2012 dataset. CMS has solid plans for accomplishing the major physics objectives. CMS has 241 publications with twelve in preparation. Thirty-three new analyses were approved for the early summer conferences and the approved analyses included new results from the heavy-ion programme. For the data processing, the 8 TeV centre-of-mass energy re-reconstruction using the 53X release was successfully completed and certified for all data including the ‘parked’ sets to provide the final 2012 data set. On-going production tasks include generation of Monte Carlo samples for H → γγ and a programme of work to provide the final 7 TeV centre-of-mass energy sample for digital treatment. This programme will reprocess the Run I 7 TeV centre-of-mass energy data and Monte Carlo samples with a single release (53X), which required solving some technical issues concerning operating system versions and porting the appropriate trigger list for this older data into a new computing release. It will also include the final alignments and calibrations.

Long Shutdown 1

The work scheduled for LS1 is considered as an underpinning for the long-term operation of CMS. As outlined in previous LHCC sessions, the programme of work has the following major elements: (1) muon upgrades, including the installation of the 4th layer end-cap Cathode Strip Chambers (CSCs) and Resistive Plate Chambers (RPCs) and the YE4 shielding wall, plus upgrade of the ME1/1 CSC front-end electronics and displacement off-detector into the service cavern of part of the barrel muon on-detector electronics; (2) the first stage of the Hadron Calorimeter (HCAL) phototransducer consolidation/upgrade (for the Hadronic Outer (HO) and Hadronic Forward Calorimeters (HF)); (3) and Tracking system upgrades and consolidations including the installation of the 45mm outer diameter beampipe, necessary for the subsequent pixel tracker upgrade. A key priority for the shutdown is enabling the Tracker to operate 30 degrees colder than its current operating temperature. Without this intervention its performance degradation due to radiation would become significant before the 300-500 fb-

1 expected by Long Shutdown 3 (LS3); (4) installation of optical splitters in the

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Electromagnetic Calorimeter (ECAL) and CSC read-out to allow commissioning of the trigger upgrade in parallel to operation and (5) installation of a new central DAQ system (DAQ2) addressing the replacement of computing and network equipment which has reached its end-of-life and the support of sub-detectors with new µTCA back-end electronics; (6) consolidation and re-work intended to provide additional robustness or longevity in the electrical, cooling and cryogenic systems and in the magnet power and control system; and (7) improvements to the heavy moving and radiation protection infrastructure to facilitate quicker opening / closing and maintenance work on the detector with lower risk to personnel and to the detector. The LHCC recognises the impressive planning and skilful execution of the shutdown work.

The LS1 work on infrastructure and services is going according to plan. The maintenance of the chilled water system is now complete with a target date of 12 June 2013 to restore the underground cooling. For the surface buildings, cooling is already available, allowing removal of the temporary chillers that maintained cooling for the High-Level Trigger (HLT) farm and the pixel laboratory over the past four months. The re-wiring of the electrical switchboard is complete, with the power to the racks to be available as soon as the cooling is restored, and the rack turbine maintenance is also complete. The new high-performance dry gas plant has been commissioned with a few remaining safety issues being resolved.

The Muon system upgrade of the CSCs and RPCs are on schedule. 65% of the ME4/2 chambers have been assembled. For the ME1/1 refurbishment, seven of the seventy-two chambers have been removed and all of the necessary on-board electronics for the refurbishment are in production, with 92 of 550 digital cathode front-end boards (DCFEB) received. Comprehensive testing is taking place in preparation for the first end-cap reinstallation planned for October 2013. The status of the RPC upgrade is that 32 RE4 chambers have been produced at CERN and in Ghent and have been accepted, with a projected production rate of 10 per week. Assembly of the first disk of 36 supermodules will start in June 2013.

The silicon pixel detectors are on the surface and are stored cold in the new pixel laboratory at Point 5, and the pixel repair & maintenance has started and is on schedule. Commissioning the strip detectors at lower temperatures will start in September 2013, following the intensive programme of re-working the Tracker environmental seals, which is getting underway now that access to the vacuum tank surfaces is available. The beam pipe delivery is expected to be on time despite a mishap with support collars getting lost while in transit. Replacements have been ordered.

The components for the replacement of photomultipliers (PMTs) and Silicon PMTs (SiPMs) for the HF and HO also remain on schedule. The Clock-and-Control Module (CCM) replacement cards have been certified and are being installed. The HO SiPM modules are being assembled and tested. For the HF PMTs, installation of 25% of the Readout Boxes is expected by the end of June 2013. The µTCA back-end electronics had a production readiness review on 12 June 2013.

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Run II Preparations

Preparations for physics readiness for Run II are progressing well and will be covered in greater detail during future LHCC sessions.

Phase 1 Upgrades

The Level-1 Trigger Upgrade Technical Design Report (TDR) for Phase 1 (CERN-LHCC-2013-011) was presented to the LHCC after an internal CMS review. The Level-1 trigger upgrade goals are to use elements of upgraded detector systems to maintain sensitivity for electroweak scale physics and for TeV scale searches at levels comparable to Run I sensitivity. The Level-1 trigger upgrade project has a projected cost of 5.7MCHF.

The Phase 1 trigger upgrade is motivated by the need to maintain physics acceptance during increasing luminosity and beam energy while constrained by the limitation of the CMS detector electronics to a maximum Level-1 trigger rate of 100 kHz.

The Phase 1 trigger upgrade programme features activities for the calorimeter trigger that uses higher segmentation and a muon trigger that will combine information from the three separate muon systems at an early processing stage. For the calorimeter, energy measurements from the ECAL, fine-grained regional energy depth segmentation from the HCAL components and forward hadron energy are used to construct candidates as part of the regional calorimeter trigger. Those candidates are forwarded to a global calorimeter trigger that constructs final electromagnetic (EM) particle candidates, jet candidates, hadronic tau candidates and global energy sums. The upgrade will enable pile-up subtraction to be implemented at the trigger level improving electromagnetic object isolation, jet finding and hadronic τ identification. For the muon upgrade, all muon system information is combined into muon candidates and isolation criteria are applied in the global muon trigger, which also includes pile-up subtracted calorimeter information. At the global trigger stage, responsible for the final Level-1 accept, all final candidate information from the individual global triggers is available for event level selection criteria, allowing for sophisticated relations involving the input objects.

In addition to physics selection improvements, the upgrade also affords the opportunity for technical improvements, achieved by introducing a flexible architecture that relies on field programmable gate arrays (FPGAs) that will enable progressive algorithmic improvements as understanding is gained. Old hardware will be replaced and consolidated with three standard types of boards, all of which are Virtex 7 FPGA-based with fast optical connections, in μTCA standard, which will improve maintainability of the system. Additionally, the number of available triggers will be extended from the current limit of 128.

To make the scientific case, physics studies with simplified trigger menus were presented in the proposal to illustrate thresholds attainable within an overall fixed rate for differing beam conditions and to demonstrate efficiencies for physics signatures with those thresholds. The menus were comprehensive and included isolated single lepton triggers, di-lepton triggers, lepton cross-triggers (lepton and jets or missing transverse energy MET) and hadronic triggers. Efficiencies were studied for high-priority benchmark channels motivated by the goal to measure Higgs properties as precisely as possible and to continue probing for new physics. The heavy -ion programme benchmarks were also included and used to assess the

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underlying event subtraction. The signal efficiencies for benchmark physics channels were compared for 2012 analyses with and without the Level-1 trigger upgrade at different luminosities using the toy menus. These studies demonstrated noticeable efficiency improvements in all channels. The most dramatic improvement was observed in channels involving τ-leptons as the current (jet based) τ-lepton algorithm is sensitive to high pile-up conditions. The upgrade τ-lepton algorithm, which is based on an e/γ algorithm, reaches high efficiency and is well behaved with pile-up increase.

The design calls for a staged installation to allow the new trigger to be developed and commissioned in parallel to operating the current trigger, removing some dependencies on the LHC schedule. The electronics for splitting the signals from the ECAL and HCAL will be installed during LS1 as will the Mezzanine cards for the End-cap Muon Track Finder. Commissioning of the new calorimeter trigger will occur in 2015. Commissioning of the new muon trigger will begin in 2015, using a slice of the mini DT and full CSC and RPC data with the final system available for physics for the 2016 LHC run.

The LHCC referees note that the trigger upgrade is well motivated and CMS prepared comprehensive answers to questions posed by the referees. The simulation of the physics benchmarks, the demonstration of physics performance and the construction of the physics list provide a persuasive case. The trigger upgrade makes good use of other upgrades in the muon system and HCAL to add information to the triggering system, adding flexibility. Additionally, the upgrade is well motivated technically by adding commonality and standardisation. The FPGA-based design will add significant flexibility and a solid foundation for future developments. CMS is aware of the complexities of programming FPGAs and is planning to make test stands available to facilitate engineers working with physicists on algorithm development. There has been extensive prototyping and at this time the installation of the splitters during LS1 is on track. The trigger upgrade is an ambitious programme with the primary technical risk identified as a delayed start of production and installation, which would complicate the accomplishment of the project by its 2016 target. The LHCC recommends approval of the CMS Level-1 Upgrade.

As an additional upgrade, CMS is evaluating internally two proton spectrometer proposals with physics programmes that intend to complement the Phase 1 high luminosity physics programme. Similar in timescale and cost while differing in technologies, the proposals call for the installation of spectrometers in the region of 200-250 m (after the LS1 shutdown) and involve an anticipated investment of 1 MCHF. Feasibility of the operation of detectors close to the beam line in low-β and high luminosity runs is yet to be fully understood for the two different detector options. Final conclusions are expected around the end of July 2013.

CMS is considering collaborating with TOTEM in carrying out the initial phase of this programme until Long Shutdown 2 (LS2). The LHCC strongly encourages CMS to follow up on this, which could be to the mutual benefit of both Collaborations.

Phase 2 Upgrades

An important CMS activity is now dedicated to preparations for the Phase 2 upgrades. CMS is developing detector concepts to serve as baselines for a Technical Proposal in 2014. Phase

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2 preparations were discussed at a CMS internal meeting at DESY in early June 2013. The goal of this meeting was to outline the Phase 2 scenarios and options, detailing the performance studies that are necessary to understand the scope and design considerations and to understand the detector longevity, infrastructure and the technical constraints in the experimental areas.

This will enable CMS to identify critical studies, necessary R&D and the cost scale for the upgrade. Phase 2 performance and physics studies will be captured in White Papers to be submitted to the Snowmass workshop, including Higgs projections, new particle searches, Standard Model processes and general considerations. Studies will also be presented at the ECFA High-Luminosity LHC (HL-LHC) workshop in October 2013.

CMS intends to present the status of on-going work to develop the anticipated Phase 2 scope to the next session of the LHCC in September 2013 and to the Resources Review Board (RRB) session in October 2013. A document summarising the scope and estimated costs for Phase 2 will also be submitted to the October 2013 of the RRBs. The LHCC strongly encourages CMS to submit this document as an important step of the CMS planning process, as well as facilitating a preliminary assessment of the entirety of the Phase 2 detector plans for ATLAS and CMS.

9. DISCUSSION WITH TOTEM

Physics

The TOTEM Collaboration presented the status of a broad set of on-going analyses and analyses that are just starting from Run I. Over twenty analysis topics were listed, including single and double diffraction, low-mass double pomeron exchange, charged-multiplicity distributions, hadronic-Coulomb interference and elastic cross-sections. Variants of these studies arise from use of data with different beam conditions (β*=11 m, 90 m & 1000 m), centre-of-mass beam energies (2.76 TeV, 7 TeV and 8 TeV), and collision types (proton-proton and proton-Pb). Several of these studies involve correlations with triggers and final state measurements from the CMS experiment. Many new preliminary results, to be finalised for publication, were reported. Among these, the first measurement of the ρ parameter at 8 TeV, measurement of slopes and cross sections of single diffractive final states at 7 TeV, of double diffractive cross sections at 7 TeV, of dN/dη for inelastic, single-diffractive enhanced, and non-single-diffractive enhanced final states (joint analysis with CMS). TOTEM also illustrated the prospects for very interesting measurements of low-mass double pomeron exchange final states, with exclusive reconstruction in the CMS detector of individual resonances, and enough information to fully reconstruct the resonances quantum numbers and properties. Furthermore, TOTEM informed the LHCC of the status of the negotiations with CMS to establish the rules necessary to control the publication and the presentation of joint analysis results.

The Committee congratulates TOTEM for the impressive progress on all these analysis fronts, and looks forward to the next round of publications.

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The Committee also congratulates TOTEM and CMS for their successes in jointly using the detectors and for producing common results and publications. The LHCC recognises the considerable physics potential of these joint analyses.

Consolidation and Upgrades

Consolidation work during Long Shutdown 1 (LS1) in underway and is on schedule. The Roman Pot detectors at 147 m have been removed and taken to the H4 beam area at the SPS. The Engineering Change Request (ECR) for their relocation to the new position at 210 m is ready. Studies continue to identify the best ferrite material to replace the one currently in use in order to contain the Higher Order Mode (HOM) heating. A final technical decision on all the Roman Pot modifications is expected for the end of July 2013. The TOTEM proposal for an upgrade of the Roman Pot systems has been presented to and discussed with CMS, which is reviewing it as part of its upgrade planning for the forward region. In case of a positive assessment, TOTEM is expected to receive from CMS a proposal for a Memorandum of Understanding.

Finally, the Committee takes note of the TOTEM upgrade proposal, submitted by the Collaboration at the end of this LHCC session. The proposal illustrates the physics case, the running scenario, the trigger strategy, the upgrades of the Roman Pot detectors and their instrumentation, the integration with the CMS DAQ system, the expected physics performance, and the timeline and cost estimate. It will be reviewed by the LHCC and a more detailed report will be given at the September 2013 session of the Committee.

10. DISCUSSION WITH LHCf

The LHCC considers that LHCf has made excellent progress in all aspects of the experiment and the Committee congratulates the LHCf Collaboration on its achievements.

The LHCf Collaboration presented a first assessment of the data taken during the 2013 runs (in proton-Pb and proton-proton collision modes at a centre-of-mass energy of 2.76 TeV), and the preliminary results in the measurement of neutron spectra from the 2010 7 TeV centre-of-mass run.

The 2013 data were collected with the Arm-2 detector. Data taking included a 20-40 Hz common trigger with ATLAS. This will allow the measurement of photon spectra as a function of the impact parameter of the proton-Pb collision using the correlation of the impact parameter with the number of hits measured by the ATLAS LUCID detector.

The neutron analysis has so far focused on Arm-1. Validation studies of the detector modeling have been completed, comparing the simulation against test beam data using the 350 GeV proton beam from the SPS. The detector simulation has been applied to events obtained with various Monte Carlo generators, and compared against unfolded data from the 2010 run. None of the models provides a satisfactory description of the data. The analysis will continue with the unfolding of the distributions, the study of the systematics, and the extension of the analysis to Arm-2.

Preparations for the post-Long Shutdown 1 (LS1) run are on-going. The plastic scintillators and fibres of Arm-1 are being replaced with GSO scintillators and bars. The detector will be

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ready for test beam with heavy ions at HIMAC (Japan) in winter 2013. The silicon strips of Arm-2 have been replaced, doubling the dynamic range and changing their positions to improve the energy measurement. The detector will be tested at HIMAC in July 2013. Final assembly will take place in Florence in early 2014, and by the end of 2014 the detectors will be exposed to the SPS test beam and installed in the LHC tunnel. The LHCC endorses the request for test beam time on the North Area T2-H4 line at the end of 2014.

LHCf presented their requests for the running conditions in 2015. The instantaneous luminosity should be in the range of 6 × 1028 cm-2 s-1, with 40 bunches of 8 × 109 protons (as well as some non-colliding bunches). A pilot run of a few hours, to integrate 1-2 nb–1, should be followed after 1 week by a 1-2 day run, with a goal of 5-10 nb–1. An unspecified amount of additional running time is also requested for data taking at centre-of-mass energies of 7 TeV and 3.5 TeV. The maximum exposure tolerated by the detectors is about 1 kGy. With the detectors in the garage position, at about 10 cm from the beam line, this corresponds to about 0.5 fb–1 of proton-proton collisions. It is thus mandatory that the LHCf physics runs be planned before the LHC delivers this amount of integrated luminosity. The LHCC recommends that the constraints set by the LHCf experiment be accounted for in the planning of LHC operations at the start of the 13 TeV centre-of-mass run.

11. DISCUSSION WITH MoEDAL

The LHCC reviewed the status of the MoEDAL experiment, including progress made in the construction and deployment of the MoEDAL detector. The LHCC acknowledges the multi-prong approach carried out for this experiment.

MoEDAL is an experiment designed to search for highly-ionising particles at the LHC (monopoles/dyons), as well as stable and pseudostable singly- and multi- charged heavy particles. The detector is based on track-etched detectors and is housed in the LHCb Vertex Locator (VELO) cavern. The MoEDAL detector is made of an array of plastic low threshold (5 MIPs) Nuclear Track Detectors (NTDs) for a total surface of 10 stack sheets of 25 m2 each, the largest passive array ever deployed at an accelerator. In order to increase the acceptance, three layers of light flexible NTD foils, with higher threshold (50 MIPs), compose the Very High Charged Catcher (VHCC). The Magnetic Monopole Trapper (MMT) is an array of Al trapping volumes deployed to stop magnetic monopoles and other very highly-ionising particles. The TimePix Radiation Monitor measures the radiation background in real time.

Twenty NTD plastic detectors were calibrated in 2012 and 2013 at BNL’s NSRL facility using Fe heavy-ion beams of 1 GeV/nucleon. In January 2011, the Collaboration deployed one third of the full detector, which was removed in 2013 before the proton-Pb run. This plastic is now being analysed. Fresh plastic was deployed just prior to the proton-Pb run in 2013.

A test deployment of 11 boxes of the MMT sub-detector was performed in September 2012. The analysed test sample of MMT (using an ETH SQUID) has shown a sensitivity of the SQUID better than ±0.01gd (where gd is the Dirac magnetic charge). The deployed boxes have been removed and will be passed through the SQUID in July 2013.

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First results for the TimePix Radiation Monitor have been presented for the Pix Chip deployed in February 2012. Tracks from highly-ionising particles have been detected and scanning and calibration is on-going.

Analysis and calibration of the removed detectors are progressing well. MoEDAL has four publications in preparation.

The goal of the Collaboration is to have the full detector deployed in 2014 and then collect data in order to reach an integrated luminosity of 10 fb-1 at 14 TeV centre-of-mass energy. The construction and installation of the full detector is proceeding within the presented timescale. The Committee received a detailed plan for the installation of the full NTD detector in 2014. This provides the Committee with details to establish the procurement of the plastic and the various options that can be followed to have it available before the installation.

12. REPORT AND DISCUSSION WITH THE WLCG REFEREES

General

The LHC experiments had a successful reprocessing period, with several important steps already completed. The activity related to data analysis remains intense and the preparations for the next data-taking period have started.

The resources recommended by the Computing Resources Review Board (C-RRB) assume a flat funding profile for the period 2013-2015. The expected increase in needs, in particular corresponding to the start of the data taking in 2015, should therefore be absorbed in technological improvements, either from increased performance of the new hardware or from intrinsic software, from applications or from data model adjustments. The LHCC notes that the computing scrutiny process will be consolidated and the RRB Computing Resources Scrutiny Group (CRSG) will closely work with the WLCG Management Board towards a procedure to refine the assessment of the experiments’ needs.

The European Union funding for the Grid middleware is close to the end of the present cycle. A new cycle is expected to start only next year, leading to a potential danger of discontinuity in functions and expertise. The new organisation of CERN-IT takes into account the decrease of the on-going European Union projects and is structured along three sections: Operations and Liaison; Monitoring Infrastructure; Information and Data. This organisation is well perceived by the LHC experiments. The Wigner Centre in Budapest is now operational with 5000 cores, a few PB of disk space and a 2 ×100 Gb/s network connection.

ALICE

ALICE runs routinely close to 40 000 jobs with a CPU efficiency exceeding 90-95%, demonstrating the clear progress in job efficiency. About a quarter of the CPU usage is devoted to the analysis, half of which runs via analysis trains. The reprocessing follows the defined strategy: proton-Pb collision data is processed now, then the 2010/2011 data (proton-proton and PbPb) and Monte Carlo will follow, using the 2012 calibration scheme. The improvements foreseen in analysis trains turnover is expected to attract more users. An offline software upgrade is foreseen for Run III (Technical Design Report expected in autumn 2014) within the O2 project. This includes a massive usage of the High Level Trigger (HLT)

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leading to a large reduction factor in event size, together with many improvements and updates in software and computing strategy, a few of which will also be implemented in parallel in the present framework. It is noted that GEANT4 starts to be used for simulation, thus allowing new capabilities to be implemented (multi-threading, GPUs etc.) as they become available. A possible general resources usage scheme based on virtualisation is under study and may allow a flexible usage of the available resources.

ATLAS

The improvements of the ATLAS software framework have been documented and approved within the Collaboration. The funding profile approved by the CRSG induces tensions in processing plans, in particular for tapes. A cleaning campaign has been started in a few Tier-1 centres to recover at least part of the deficit. The processing procedure using the HLT is commissioned and ready to start as soon as the hardware is completed. An opportunistic usage of Google cluster is noted (4000 cores for two months), thereby proving the ability to make usage of different computing frameworks.

CMS

CMS finalised the reprocessing in the Tier-1 centres and massive Monte Carlo requests are being prepared. The preparation of the next data-taking period as well as a massive production of LHE (“Les Houches Event”) files is expected to lead to an intensive usage of resources in the second half of the year. The main objective of the on-going work to improve the offline software is an efficient usage of resources. A few items are mentioned: the use of the CVMFS network file system for releases distribution; disk-tape separation in the Tier-1 centres; xrootd deployment; multi-core project; HLT commissioning for offline reprocessing; and improved data management. The new analysis framework (CRAB3) will use PANDA (ATLAS product) back-end.

LHCb

LHCb is proceeding to the re-stripping of 2010 and 2011 data and expects to process and strip soon the 2013 proton-Pb data as well. The simulation within the 2012 configuration is commissioned. The HLT farm is routinely used and its contribution to the processing power is significant (largest contribution to the total CPU). The disk deficit expected in 2013 may be recovered due to delays and rescheduling of various reprocessing tasks. The installation of disk and analysis usage at selected Tier-2 centres (named T2Ds) will be tested shortly, with the goal to define about ten T2Ds with more than 300 TB each. The massive access to tapes (3.8 Pb) for re-striping revealed some potential issues for tape usage and recovery, which may deserve some further investigations, although no data was endangered or lost in the process. The planned software improvements include technical updates (compiler, C++11, root6) as well as changes in distributed computing and data model, for which internal reviews have been pursued recently. The scalability of the DIRAC transformation database, the validation procedures (with a possible collaboration with CMS), as well as the documentation, were the focus of the distributed computing review. The new data model will address multiple trigger streams, use of T2D sites, data placement optimisation and a new definition of data formats from master Data Summary Tapes (DSTs) to mini-DSTs (mDSTs). The ambitious

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improvement plan for Long Shutdown 1 (LS1) is endangered by the lack of person-power in the offline software area.

Data Preservation

The LHCC has welcomed a presentation on Data Preservation in High Energy Physics on behalf of DPHEP, an international study group was formed in 2009 as an ICFA panel. The LHC experiments officially joined DPHEP in 2011 and initiated a reflection on various items including data persistency and open access, collaborating also within a local task force. A recent ICFA statement encourages laboratories, institutes and experiments to review the draft DPHEP Collaboration Agreement with a view to joining by mid- to late-2013. The long-term perspectives on data preservation are recognised by the experiments as beneficial for the stability of the computing models and have in addition a clear potential for synergies within high-energy physics and beyond. Multi-disciplinary projects have started and are being planned in Europe and in the US at national and international levels. A strategic vision on data preservation is prepared at CERN and the LHC experiments are encouraged to actively take part to this process.

Conclusions

The LHCC congratulates the WLCG and the LHC experiments for a successful computing performance during the first LHC running period and for their plans to improve the efficiency of the computing models. The LHCC would like to note that an adequate support for an efficient usage of the collected data is crucial for the LHC physics programme. The allocated resources cover satisfactorily the needs, however, the increase in activity expected after LS1 is at present only partially covered by the projected resources plan and the main assumption is that technology and data model improvements will allow resources to fit within the pledged resources. The LHCC notes the initiative to enhance the contacts between WLCG and the CRSG, and would like to continue the good cooperation with both in order to ensure a robust and efficient resources provision for LHC computing. The on-going work on the data model improvements by all experiments is an essential ingredient for the next LHC running period. The LHCC notes that ambitious improvements are being investigated (data model and distribution; software upgrades; analysis strategies; and virtual computing) or already commissioned (HLT farms and external resources) and expects a quantitative evaluation of the impact of these improvements to be part of the document prepared by the experiments for the next LHCC session. In particular, the cross-collaborations on methods or frameworks to improve the efficiency and the versatility of the analysis frameworks, as well as the opportunistic usage of external resources are very positive evolutions. Finally, the LHCC encourages the LHC experiments to consider the long-term data preservation and the open access aspects as part of the continuous improvements in the data models and to participate in the DPHEP collaboration and to further initiatives planned in this context at CERN and elsewhere.

13. REPORT ON RD39

The LHCC heard a report from the RD39 referee on the Collaboration’s programme concerning the operation of solid-state detectors at low temperatures and in a high radiation

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environment. The referee summarised the experimental results that RD39 has achieved on the development of such detectors.

The Committee took note of the progress made during 2012 in the study of 3D trenched-Charge Injection Devices (CIDs) cryogenic detectors. Silicon detectors produced by RD39 were successfully tested in particle beams and by laser Transient Current Technique (TCT) measurements. Detectors were irradiated up to a fluence of 1016 neq / cm2 using a 9 GeV proton beam from the CERN Proton Synchrotron. The Collaboration showed that the signal from the Si detector is readable at LHe temperature after such an irradiation and that trapping at LHe temperature is about seven times more than predicted at room temperature. RD39 also showed that at LHe temperature, single-crystal Chemical Vapor Deposition (scCVD) diamond produces a signal that is about 30% higher than Si detectors of a comparable size. This is likely attributed to the different trapping characteristics of diamond and Si at very low temperatures. These results are still preliminary and need further investigations and understanding.

Applications of silicon detectors at 1.9 K for the machine Beam Loss Monitors (BLMs) remains an interesting project as such monitors could be considered for installation inside the magnet cold mass and close to the interaction region.

As was the case last year, the Committee concluded that the development of CID is slow and the technology is not yet considered as an option for an LHC detector upgrade. Although the RD39 Collaboration is a small group, it does possess special knowledge and techniques and the RD39 programme of study of radiation-hard silicon sensors operated at cryogenic temperatures - CID and applications to the LHC machine – is worth continuing.

The referee recommends that emphasis henceforth should be placed on the development of the BLM with the LHC machine groups while the R&D on the CID sensors should be progressively integrated into RD42 and RD50. The Committee agrees with the recommendation of the referee.

14. REPORT ON RD42

The LHCC heard a report from the RD42 Collaboration on its programme to develop intrinsically radiation-hard Chemical Vapor Deposition (CVD) diamond tracking detectors for experiments at high-luminosity colliders. The Collaboration has about 100 members from 30 institutes. The two main technologies being pursued are poly-crystalline CVD (pCVD) and single-crystal CVD (scCVD) diamond. There remain very few suppliers for production of devices that meet the Collaboration’s specifications. The Collaboration reported that all large samples this year were requested from the company II-VI: 26 ATLAS sensors have been received and 20 CMS sensors are still to be delivered. The radiation damage analysis, both with 800 MeV and 24 GeV protons, has been continued and shows that the Displacement Per Atom (DPA) model of damage in diamond describes the data best. The Committee notes that these results have been shown widely and recommends publication.

The performance of the Precision Luminosity Telescope (PLT) for CMS during the pilot run was described. The PLT is a stand-alone luminosity monitor, with 3 planes of 8 pixel sensors each at either end of CMS. These scCVD sensors permit a high precision measurement of the

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luminosity bunch-by-bunch. The detector has seen about 20 pb-1 of data and has run with an average efficiency of 70% for a single plane. An improved efficiency is seen after surface treatment of irradiated sensors. The Collaboration intends to apply this surface treatment to all sensors in the preparation of the PLT for the 2015 LHC run.

The Collaboration has successfully operated the diamond Beam Conditioning Monitor (BCM) installed in the ATLAS experiment, which was used as the standard luminosity monitor at the end of Run I. The Collaboration has been constructing the Diamond Beam Monitor (DBM) for the ATLAS experiment, which consists of four 3-plane pixelated pCVD diamond stations on each side of the ATLAS experiment. Three test beam campaigns were held with prototype devices to characterize their performance. There are residual bump bonding issues, which are being addressed. It is expected that 30 modules will be delivered in time for installation during Long Shutdown 1 (LS1). More than half of the sensors are from the supplier II-VI.

The role of the RD42 Collaboration in developing pixelated diamond sensors for the community is well established and its benefit to the community has been clearly demonstrated. The LHCC considers that the proposed research programme for next year is reasonable and encourages publication of the irradiation study results. The future research programme includes further irradiation studies and the characterisation of irradiated samples; continuation of the development of additional diamond manufacturers to expand production capabilities; and continued overall support of the LHC upgrade pixel projects.

In order to continue their research programme, the RD42 Collaboration requests that the CERN RD42 group be maintained at the current level. The Committee notes that the RD42 research programme immediately benefits the LHC experiments and fully supports its continued research programme.

Under the above terms, the referees recommend that the RD42 project be continued in 2013. A status report is expected to be submitted to the LHCC in one year’s time. The Committee agrees to the continuation of the project on this basis.

15. REPORT ON RD50

The LHCC heard a report from the RD50 referee on the Collaboration’s programme concerning the development of radiation-hard semiconductor devices for very high luminosity colliders. The referee summarised the experimental results that RD50 has achieved on the development of such detectors and also described the proposed programme for future work.

The Committee took note of the good progress in the study of such devices for applications in future high energy physics experiments, such as those at an upgraded LHC. A number of areas of progress were presented, including the further understanding of radiation damage effects at the microscopic level; the systematic analysis of the charge multiplication mechanism; the simulations based on the TCAD software tool; consolidation of data obtained on p-type and thin-segmented sensors; and new structures based on mixed telescopes.

The LHCC considers that the RD50 is an active, productive and diversified R&D Collaboration. The LHC experiments have profited from the work of RD50 and their work is vital for the upgrades of the LHC experiments and for other experiments as well. The Committee also considers that the proposed work plan for 2013/2014 is reasonable. Work is

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planned to be carried across all fields of study – defect and material characterisation; detector characterisation; new structures; full detector systems; and links to LHC experiments and their upgrade working groups. The Committee also took note of the financial support through the PH Department R&D funding and the continuing use of laboratory, infrastructure and technical support from CERN.

In view of the above and given the modest request for resources for further work, the referee recommends that the R&D project be continued in 2013/2014. A status report is expected to be submitted to the LHCC in one year’s time. The Committee agrees to the continuation of the project on this basis.

16. REPORT ON RD51

The LHCC heard a report from the LHCC on its programme to develop advanced gas-avalanche Micro-Pattern Gas Detector (MPGD) Technologies. The RD51 Collaboration aims to facilitate and advance the technological development of MPGDs and associated electronic read-out systems for applications in basic and applied research. The group serves as an access point to the MPGD technology for the worldwide community and its research focus has been on the development of techniques for detectors in high-rate environments while improving the space-point resolution and the radiation hardness of the detectors.

The Collaboration has about 450 people from 80 institutes organised around seven working groups. The main technologies being pursued are Micro-Mesh Gas Detectors (Micromegas), thin and thick Gas Electron Multiplier (GEM) devices, detectors with CMOS pixels and micro-pixel chambers. The deployment of the MPGD technology in running experiments has increased substantially and RD51 serves a very broad user community.

The Committee took note of the numerous RD51 achievements. These include the production of medium-scale MPGD production in the CERN workshops; the development of large-are GEM and Micromegas detectors; the development of Scalable Read-out System (SRS) electronics; and the progress made in the simulation tools. The RD51 activities have been shown to have direct relevance to the LHC experiments as the RD51 MPGD technology is being demanded for the LHC experiment Phase 1 upgrades.

The referee also reported on RD51’s plans for beyond 2013. The plans include continuation of R&D support for the LHC experiments and their upgrades; generic R&D; development and maintenance of software and simulation tools; development and maintenance of software of SRS electronics; industrialisation of the MPGD technology; maintenance and extension of the RD51 laboratory and test beam infrastructure; efforts in education & training for MPGDs; and the organisation of a series of specialised workshops.

In summary, RD51 is a successful R&D Collaboration with well-defined and important future plans. In view of the above and given the modest request for resources for further work, the referees recommend that the RD51 R&D project be continued for five years beyond 2013 and for CERN to continue to provide the limited requested support to the Collaboration. A status report is expected to be submitted to the LHCC in one year’s time. The Committee agrees to the continuation of the project on this basis.

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17. REPORT ON LETTER OF INTENT ‘DEVELOPMENT OF PIXEL READ-OUT INTEGRATED CIRCUITS FOR EXTREME RATE AND RADIATION’

The LHCC heard a report on the Letter of Intent (LoI) to form an RD collaboration on Pixel readout integrated circuits (CERN-LHCC-2013-008). The Committee would like to commend the proponents of the LoI for the presentation and the initiative to establish such a collaboration.

The challenges of the upgrades of the LHC experiments are formidable and the area of research suggested in the LoI addresses a key issue relevant for future experiments and upgrades of existing experiments, namely the integration of high-density radiation-hard readout components in the integrated circuit design technology. The 65 nm technology offers advantages; the introduction of the technology however is demanding and not without risk.

The LHCC is pleased to see a focused and ambitious effort being launched by the ATLAS and CMS Collaborations to develop the technology for applications at the LHC. The Committee recommends the creation of the RD group for a period of three years, the time frame for the maturing of the technology to be used for the LHC upgrade scenarios.

18. REPORT ON LETTER OF INTENT ‘3D SENSORS AND MICRO-FABRICATED DETECTOR SYSTEMS’

The LHCC heard a report on the Letter of Intent (LoI) to form an RD collaboration on 3D Sensors and Micro-Fabricated Systems (CERN-LHCC-2013-010). The Committee would like to commend the proponents of the LoI for the presentation and the initiative to establish such a collaboration.

The challenges of the upgrades of the LHC experiments are formidable and the area of research suggested in the LoI addresses key issues relevant for future experiments and upgrades of existing experiments. The Committee notes that the projects proposed in the LoI are heavily oriented towards high-luminosity operation of the LHC. The Committee also observes that much of the necessary work is already taking place within the existing LHC experiment collaborations. As such, the near-term objectives of the RD proposal are sufficiently covered by these efforts.

The LHCC evaluated the potential added value of the RD programme presented in the LoI beyond the current on-going efforts. The Committee considers that the LoI falls short in presenting a sound case for this most important aspect. The Committee encourages the proponents of the LoI to articulate the strengths and added value of their RD for particle physics over the long term. The Committee will reconsider the LoI once this additional information is submitted to the LHCC.

19. CLOSE-OUT WITH THE DIRECTOR FOR RESEARCH AND COMPUTING

The LHCC summarised with the Director for Research and Computing the status of the experiments and their plans for the future. The discussion concentrated on the status of the LHC machine and experiments and the activities for the upgrade of the experiments. It was decided that at its session in September 2013, the LHCC deliberate on the Phase-2 upgrades of the LHC experiments.

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20. REFEREES

The LHCC referee teams for this session are as follows:

ALICE: J.-C. Brient, D. D’Enterria,), T. Ullrich (Co-ordinator) ATLAS: U. Bassler, P. Burrows, C. Cecchi, R. Roser (Co-ordinator) CMS: A. Boehnlein (Co-ordinator), M. Demarteau, D. Denisov, T. Mori LHCb: C. Diaconu, G. Eigen, S. Miscetti (Co-ordinator) TOTEM, LHCf, MoEDAL: U. Bassler, C. Cecchi, D. D’Enterria, M. Mangano LCG: A. Boehnlein, J.-C. Brient, C. Diaconu (Co-ordinator), T. Mori

Experiment Upgrades:

General: J.-C. Brient, M. Demarteau (Co-ordinator) RD39: G. Eigen RD42: M. Demarteau RD50: G. Eigen RD51: D. Denisov 21. The LHCC received the following documents:

CERN-LHCC-2013-004 Minutes of the one hundred and thirteen meeting held on Wednesday and Thursday, 13 and 14 March 2013

CERN-LHCC-2013-006 ATLAS New Small Wheel Technical Design Report

CERN-LHCC-2013-007 ATLAS Fast TracKer (FTK) Technical Design Report

CERN-LHCC-2013-008 RD Collaboration Proposal: Development of pixel readout integrated circuits for extreme rate and radiation

CERN-LHCC-2013-009 TOTEM Upgrade Proposal

CERN-LHCC-2013-010 RD on 3D Sensors and MicroFabricated Systems

CERN-LHCC-2013-011 CMS Technical Design Report for the Level-1 Trigger Upgrade

DATES FOR LHCC MEETINGS

Dates for 2013

25-26 September

4-5 December

Emmanuel Tsesmelis E–mail: emmanuel.tsesmelis@cern.ch Tel. 78949, 164057

LHCC Secretariat: Patricia Mage (Bldg. 3/R-018) Tel. 78135

patricia.mage@cern.ch