CMS Programme

India CERN LHC CMS India-CMS

Kajari Mazumdar (on behalf of India-CMS collaboration)

Tata Institute of Fundamental Research Mumbai

Plan is to cover briefly relevant hardware, software and physics topics.Additional material in talks by Pant, Shukla, Shivpuri .

India-CERN meeting, BARC Feb. 28, 2011

• Long association with CERN: Emulsion, Bubble chamber, LEP good name and also rapport of Indian scientists

• LHC enthusiasts’ (Rubbia, Hoogland, ..) visits India from early 90’s.• Groundwork done by Profs. Malhotra, Ganguly and others.

• Indian scientists in LHC experiments from nascent, R&D stage.• First Indian group formally in CMS experiment in1994.

LHC programme: more multi-dimensional with participation in accelerator, experiment and grid computing.Under India-CERN umbrella each community functions independently.

Projects funded by govt. agencies: Dept. of Atomic Energy (DAE) and Dept. of Science & Tech. (DST).

Prologue

Today, 6-7 Indian groups in CMS, thriving well.• TIFR, BARC, Delhi U., Panjab U., Visva-Bharati U, NISER, SINP About 40-50 physicists, engineers (+ techinical staff ) More teams expected in future

• TIFR is the host institute for India-CMS collaboration.

• Significant contributions in various fronts, though limited by‘distance’ and ‘time-zone’ factors.

• Hoping for better visibility and support in CMS collaboration in future!

India-CMS collaboration

• 40 students till now, about 10 finished Ph.D. during last 7-8 years.• More influx of teams, students expected in coming years.

Please help us in more faculty recruitment!

• Hardware (both in R&D and fabrication in current phase)

• Preparatory studies with physics simulation, contributions in LHCC and other milestone documents. Enthusiasm and moral support of Denegri acknowledged.

• Software: detector simulation, GEANT specific developments

• Test Beam activities for HCAL

• Grid computing (Tier2 centre)

• Analysis of real data => contribution in publications --- Cosmic muons recorded in CMS --- Collision data (both p-p and Pb-Pb)

• Representing CMS collaboration in international fora.

Participation of India in CMS experiment till now

• Detector upgrades, related simulations

• Sub-detector related R&D, participation in test-beam activities.

• Studies for physics potential for brighter scenarios of LHC

• More involvement in remote simulation and analysis

• Participation in various responsibilities of CMS (to be enhanced)

• Remote Operations Centre for the Asian zone requested

• Partial support for students for longer stay at CERN requested

Open to ideas for other possibilities as well.

Participation in CMS in future

Present hardware participation in CMS

1. Outer Hadron Calorimeter (HO) : TIFR+ Panjab University reduce energy leakage from HCAL: additional depth -->hermetic detector improves resolution for measurement of missing transverse energy, key observable to discoveries

Scintillator with HPD/SiPM as light readout 432 Plastic scintillator trays (4-6 units) covering ~ 400 sq. m

– 2160 readout channels – 72 honeycomb panel housings (size 2.5 m X 2.0 m)

2. Si Pre-Shower Detector (PSD) in EM CAL endcap ( talk by R.K.Shivpuri) BARC (+ BEL) + Delhi Univ.

3. Resistive Plate Chamber (RPC) (talk by L.M.Pant) BARC + Panjab Univ.

Tile with 4-s groove 5 to 6 tiles in tray. Fibres ganged together to form pigtail, to be connected via clear fibres to photo detector

Pigtail with connector

• 6 trays assembled side by side in a HO housing• various Quality Controls at each step. eg, MIP signal using cosmic muons.

• One HO module being installed on a muon ring on surface (2006) non-trivial coordination with others.

• 3-4 personnel from India at CERN at a given time forInstallation, monitoring detector health at every stage.

HO detectorResponsibility: fabrication of scintillator detectors and quality controls.

HO detectors, alongwith muon stations,being lowered down the shaft to underground area

In the underground pit

• Efficiency of HO detectors during 2010 data taking : about 97%• Calibration of HO using cosmic muons.

• Shift duties by Indians • Participation in HO readout upgrade

Issues:• HO elements do not have adequate signal to background

ratio for MIPs• HPDs in non-central position have discharging tendency

Solution: – Replace HPDs with state of-the-art device SiPM– Provides excellent S/B ratio for muons– Insensitive to ambient magnetic field

SiPM characterization facility– Setup for V-I characteristic, single pixel calibration, linearity, MIP

studies at Ooty lab. (near Bangalore)

Packaging and assembly of bare SiPMs demonstrated at Bharat Electronics Limited (Bangalore)

CMS-HO Calorimeter: present status & near-future activityCMS-HO Calorimeter: present status & near-future activity

Validation of SiPM for CMS environment– Testbeam studies, stability, radiation hardness, magnetic

field immunity, saturation effect

SiPM Control Boards fabrication• Prototype fabrication carried out in India•Production and quality control of 150 boards in India expected

Participation in Installation– Assembly of R/O box, QC and burn-in test at CERN

CMS-HO Upgrade plan: TIFR responsibilityCMS-HO Upgrade plan: TIFR responsibility

Possibility for fabrication of SiPM at India being probed.

LHC Grid Computing & CMS-T2 centre

• One of the 5 CMS Tier2 (T2-IN-TIFR ) sites in Asia Pacific region operating since last 3 years. Logical parent T1: ASGC, Taiwan

• Serving about 60 users from 6 institutes/universities in India

• CMS collaboration (>3000 people) uses the facility for

coordinated central Monte Carlo event production

planned data storage (both collision and simulation)

remote analysis of physics data with latest CMS software by any member of CMS collaboration

CMS recognizes the performance credit points exchanged against mandatory jobs by collaborators.

• Resources acc. to pledge: > 500 CPU cores, 600 TB storage can host lots of data to the advantage of whole collaboration, Indian physicists and particularly students.

• Availability and reliability of site almost 100% in recent months. (occasional short periods of bad network situation)

• Latest versions of software and middleware, regular updates.

• Trouble shooting operations taken up fast by support staff. • Data transfers at good rates (typical latency: 10 to 30 min.s).

• Good success rate of jobs during last 6 months.

With more intense LHC machine performance in coming years expects to serve the community well.

Site performance

Key to grid computing: network bandwidth

• Dedicated P2P link between CERN and India since several years. presently 1Gbps, likely to be upgraded

• With requirements of CMS computing (different from ALICE), connection to other T1s achieved (8 more) via peering at CERN end.

• Other internet facilities are improving continuously in recent timesSignificant for site performance, connected to other T2s.

• Site taken up for hosting important data streams.

• Hubs hosted at TIFR, maintained jointly by CDAC + TIFR. Presently other centres / institutes connected to outside world via TIFR

• With NKN connections fully operational in the country in near future, site expected to play bigger role for LHC data analysis by collaborating institutes. (talk on Grid by Apte)

Future possibility to use for other purposes (medical, weather, outreach,.)

Some numbers for the period of Jan. to Dec. 2010•Total amount of data transfers: 350 TB upload, 313 TB download Much more traffic expected from this years onwards

• Total number of jobs at site: 674971 (tests + simulation + analysis)

• Successful simulation event production jobs : 46510 Average cpu time for 1 p-p collision event simulation ~2.5 s

• Successful event analysis jobs: 76701

Processed events, cumulative, in 2010

1.7e9

Submitted jobs rate in 2010

12K

Physics effort from at India• simulation studies, analysis done mostly from India (+short stays @CERN).• during last several years using grid.• regular presentations of updates remotely over the network.• active discussions among CMS physicists, theorists.

Participation in pre-collision era:1. Physics simulation studies to estimate CMS potential SUSY in trilepton mode invisible Higgs in vector boson fusion process, Z ττ eµ, as benchmark for Η ττ eµ , Zbb process Search for charged higgs several topics with heavy quarks, etc.2. Test beam: study of detector response, validation of GEANT4 physics of hadronic interactions.4. calibration of HO subdetector modules 5. Trigger studies

• about 1 billion events collected in CMS detector during 2008.• efficiently used for commissioning of CMS experiment in multiple ways. angular dependence of muons data-driven method for L1 muon trigger efficiency in different regions (S.Bansal, published in JINST)

Analysis of Cosmic ray events (while waiting for collision )

Z × Φ map for RPC efficiency using Tag&Probe method

Physics with collision dataPhysicists involved heavily in several analyses topic choice based on personal taste, applicable wisdom

Notably, direct contributions in ~10 physics publications based on p-p collision data of 2009, 2010.

significant contribution in analysis of heavy ion data as well. (talk by Shukla)

Participation in analysis reviews.

Presentations of CMS physics results on behalf of whole collaboration by Indians (physicists and students) at international conferences.

First Ph.D. thesis (S.P.Singh) using collision data, in Aug.,2010. Responsibilities for trigger measurement, data quality monitor, etc.

• Hadronic event shapes• Underlying event analysis using jets reconstructed from tracks only• UE analysis using Drell-Yan events • QCD properties in hard jet events• Jet production in association with W, Z bosons

• Prompt photon production

• W charge asymmetry in production using muon channel • Diboson event properties: Wγ in muon final state • Drell-Yan events (muon)• Z ττ eµ + X

• Z’ ττ hadronic final states• exotica in electron, photon final states (e*e e+e- γ)

• Search for Higgs in WW 2l 2 ν• Search for Higgs in ZZ 2l 2ν

Physics Menu chosen at present

There is lot of interesting physics in every collision

• Detailed understanding of softer processes Discovery in hard, rare processes • CMS measures (almost) everything beautifully excellent physics output!

Hadronic event shape variables

Agree with Pythia6, Pythia8 and Herwig++ ,

Disagree with Madgraph and Alpgen

Central thrust Thrust minorEvent Shape variables can distinguish different models of QCD multijet productionPossibility with large statistics: measurement of αs Pythia6

Pythia8

Herwig

Madgraph

Alpgen

Pythia6

Pythia8

Herwig

Madgraph

Alpgen

3.2pb−1 CERN-PH-EP-2010-072To be publishd in PLB

UE measurement using Track-based Jets• 7 TeV and 900 GeV results including tunes for soft QCD: D6T and DW predictions • Charged multiplicity density and ΣpT density profiles.

• Fast rise for pT< 8 GeV/c (4 GeV/c) increase of MPI activity

• Plateau-like region (≈ constant average number of particles + slow increase of ΣpT) saturation regime

• MPIIncrease of the UE activity with energy

Stat. dominatingat high pT

Headed for publication in JHEP

UE measurement using Drell-Yan events @ 7 TeV

- Cleanest process to measure UE! Everything excluding two leptons is UE. - Unlike leading jet case, there is no colored FSR. - Scale is set by Z pT and lowest scale is set by Z mass. - For discovery, UE need to be measured for reasonably hard events, not possible, using hadronic final states.

- Away region is affected by away jet, which balances Z pT. - Transverse and toward regions are most sensitive for UE studies

Work in progress

W→μν asymmetry and parton distribution function

Charge asymmetry to constraint parton distribution functions of proton sea quark content wrt valence quarks W+ is produced more preferenatially compared to W- at LHC

μ+

μ−

CERN-PH-EP-2011-024 PLB

Ph.D thesis of A. Saha

Study of Wγ events in muon channel Diboson productions : Standard Model gauge structure self-interactions among gauge bosons: Wγ, WW, Zγ (no ZZγ,Ζγγ vertices), WZ, ZZ

--> important backgrounds for Higgs searches Wγ : largest cross section Wγ cross section measurement – step

towards measuring WWγ coupling.

Born leveldiagrams

Higher orderdiagrams

WWγ coupling

σ( pp Wγ +X µν + X, theory, NLO) pb = 49.44 ± 3.8σ(exp) pb = 55.4 ± 6.93 (stat.) ± 4.86 (syst.) ± 6.09 (lumi.)

To be published in JHEP, + presentation in students'session at Moriond conf. by D.MajumderPh.D thesis of D. Majumder

Drell-Yan process: differential cross-section

• Standard Model electroweak benchmark, not spoilt by QCD!• Handle on PDF through normalized measurement of dσ/dM • Background for New Physics searches (extra heavy gauge boson Z’ decaying to lepton pairs)

dσ/dM

σ 6 0< Mμμ1 2 0G eV=9 3 2 ± 9 s ta t ± 2 5 sy s t ± 1 1 % ,lum i pbThis measurement, with 36 pb-1

CMS in JHEP with 3 pb-1 924 ± 31 ± 22 ± 102 pb

Theoretical expectation: 970 ± 40 pb

Not final as yet, to be presented in Moriond

Major discoveries of last century with CMS

First beam at LHC: Sep. 2008, first collision at 7 TeV on March 30, 2010 Public outreach at TIFR, Mumbai, by live display of activities at CERN

Some steps being taken, though not sufficient:• Regular scientific seminars on important results from LHC• Dissemination of LHC highlights among non-HEP colleagues24X7 display of status of LHC accelerator, CMS experiment, and live events. Tier2 status LHC related popular talks at schools, public places

• LHC related colloquium at various institutes/universities• Participation in TIFR Open Day programme every year

P

Introductory talks on LHC for graduate students, summer students• Occasional reports in media

Public lectures at TIFR (by Heur, ..)

Will be keen to join LHC@home scheme!

Outreach, Education

A Personal Conclusion

• Proud to be Indian AND in CMS experiment!• CMS experiment is doing very well and the harvest is very encouraging. We have a very exciting time ahead.

• LHC is at the dawn of a new era in high energy physics.• LHC has already changed our lifestyle!• LHC will change the way mankind thinks of the universe.

• Due to timely initiatives of previous generation of scientists at both ends today we participate in the world-wide front ranking efforts.

• The potential of Indian contribution in CMS is huge and recognized already, but more needs to be done in to harness it completely. I will do my best in this regard.

THANK YOU !

BACKUP

Behind the Tracker and in front of EE2 Pre-shower Endcaps (SE)Coverage: 1.653<|η|< 2.61000 detectors

Silicon Preshower• Responsibility of BARC, Delhi University• fabrication at Bangalore with close supervision from BARC• Quality of detectors comparable to that of Hamamatsu CMS requested for more production.

Physics motivation: accurate

measurement of Higgs γγ decay

Hybrid with front endElectronics-PACE chip

Silicon detector made in BEL, Bangalore, on micro-module made at CERN

Detector mounted on ceramic & Al tile

The two separate ES Dees

Assembly/mounting at CERN

1 Gbps to CERNpeered to GEANT

2.5 Gbps TEIN3 via NKN (both to East and West)

1 Gbps GLORIADto Chicago, US

TIFR-INDIACMS T2

250 Mbps to other VECCRRCAT, IPR

VECC/SINP-INDIAALICE T2

Key to grid computing: network connections

CMS detector ¼ Longitudinal View

HBHE

HF

HO

HO: Physically attached with CMS barrel muon stations, subdivided into 5 annular rings, covering the barrel region of |η| <1.6, positioned behind magnet iron, 2 layers for |η| < 0.36

Quality control tests at India

Low-noise SiPM and its characteristics

LED calibration pulsein SiPM

HPD discharge noise in magnetic field