the moedal experiment: a progress report

James L. Pinfold LHCC Report February 2005 1

MOEDAL

LHCb

The MoEDAL Experiment: The MoEDAL Experiment: A Progress Report A Progress Report

James PinfoldJames Pinfold (for the MoEDAL Collaboration)(for the MoEDAL Collaboration)


CSR, University of Alberta, Edmonton, Alberta T6G OV1, CANADACSR, University of Alberta, Edmonton, Alberta T6G OV1, CANADA: : B. B. Caron, J. de Jong, J. L. Pinfold, J. Soukup, W. J. McDonald, Y. Yao.Caron, J. de Jong, J. L. Pinfold, J. Soukup, W. J. McDonald, Y. Yao.Main responsibility: Mechanical design/construction, calibration of plastic Main responsibility: Mechanical design/construction, calibration of plastic and Monte Carlo, and Monte Carlo,

IoP, University of Bologna, Via Irnerio 46, Bologna, ItalyIoP, University of Bologna, Via Irnerio 46, Bologna, Italy: : G. Giacomelli, H. G. Giacomelli, H. Dekhissi, A. Margiotta, L. Patrizii, P. Serra, M. SpurioDekhissi, A. Margiotta, L. Patrizii, P. Serra, M. SpurioMain Responsibility: Preparation, etching & measurement of plastic and Main Responsibility: Preparation, etching & measurement of plastic and (soon) Monte Carlo(soon) Monte Carlo CERN, Geneve 23, SwitzerlandCERN, Geneve 23, Switzerland: : M. PlacidiM. PlacidiMain responsibility: Issues to do with the beam Main responsibility: Issues to do with the beam Dept. of Physics, University of Cincinnati, Ohio, USADept. of Physics, University of Cincinnati, Ohio, USA: : K. KinoshitaK. KinoshitaMain Responsibility: Preparation, etching & measurement of plastic Main Responsibility: Preparation, etching & measurement of plastic

Lab. de Physique Nucleaire, Universite de Montreal, Succ. "A", Montreal, Lab. de Physique Nucleaire, Universite de Montreal, Succ. "A", Montreal, Quebec H3C 3J7, CanadaQuebec H3C 3J7, Canada: : A. Houdayer, C. LeroyA. Houdayer, C. LeroyMain responsibility: radiation damage effects, calibration of plasticMain responsibility: radiation damage effects, calibration of plastic Dept. of Physics, Northeastern University, 112 Dana, Boston, USDept. of Physics, Northeastern University, 112 Dana, Boston, US: : J. SwainJ. SwainMain responsibility: Monopole energy loss considerationsMain responsibility: Monopole energy loss considerations

The MoEDAL CollaborationThe MoEDAL Collaboration


• Introduction Introduction

• Radiation tolerance of the MoEDAL Radiation tolerance of the MoEDAL

• Studying the material budget in the LHCb VELO regionStudying the material budget in the LHCb VELO region

• A GEANT4 simulation of the monopole in the framework of the LHCb simulation A GEANT4 simulation of the monopole in the framework of the LHCb simulation program (GAUSS)program (GAUSS)

• A preliminary idea of the sensitivity of the MoEDAL monopole searchA preliminary idea of the sensitivity of the MoEDAL monopole search

• Moving towards the final design of MoEDAL detectorMoving towards the final design of MoEDAL detector

• Estimating backgrounds from spallation productsEstimating backgrounds from spallation products

• Monitoring MoEDAL performanceMonitoring MoEDAL performance

• Moving towards the Technical ProposalMoving towards the Technical Proposal

• Some Post TP ConsiderationsSome Post TP Considerations


A Very Brief Review of Monopole A Very Brief Review of Monopole PropertiesProperties

• Quantized magnetic charge:Quantized magnetic charge: ge=n ge=nħħc/2 c/2

• The magnetic charge isThe magnetic charge is: g = ng: g = ngDD = n = nħħc/2e = n68.5e (n=1,2,3…)c/2e = n68.5e (n=1,2,3…)

• Magnetic coupling constant:Magnetic coupling constant: g g22/hc= 34.25n/hc= 34.25n22

• Energy gain in a magnetic field:Energy gain in a magnetic field: dE/dx=gB=0.2n dE/dx=gB=0.2n22 (GeV/cm)B(Tesla) (GeV/cm)B(Tesla)

• Ionization Ionization (for (for >10>10-3-3):):

• Ionization goes up by 4, 9, 16…depending on whether n=2, 3, 4…Ionization goes up by 4, 9, 16…depending on whether n=2, 3, 4…

• Mass…not predicted by DiracMass…not predicted by Dirac

• Various theories give Monopole solutions with a range of masses – Various theories give Monopole solutions with a range of masses – assume mass is a free parameterassume mass is a free parameter


Brief Review of MOEDAL Detection Brief Review of MOEDAL Detection TechniqueTechnique

• The passage of a highly ionizing particle through the track-etch detector is The passage of a highly ionizing particle through the track-etch detector is marked by an invisible damage zone along the trajectory. marked by an invisible damage zone along the trajectory.

• The damage zone is revealed as a cone shaped etch-pit when the plastic The damage zone is revealed as a cone shaped etch-pit when the plastic detector is etched in a controlled manner using a hot sodium hydroxide detector is etched in a controlled manner using a hot sodium hydroxide solution. solution.

• The depth of the etch pit is an increasing function of the particle The depth of the etch pit is an increasing function of the particle Z/Z/• This is a well studied, simple, easy to calibrate and cost effective technique This is a well studied, simple, easy to calibrate and cost effective technique

Look for aligned etch pitsIn multiple sheets


Other Possible Physics AimsOther Possible Physics Aims

• Dyons – particles with electric Dyons – particles with electric & magnetic charge& magnetic charge

• Massive (quasi) stable exotic Massive (quasi) stable exotic particles (Colour sextet quarks, particles (Colour sextet quarks, SUSY MSE particles, etc.)SUSY MSE particles, etc.)

• Massive (quasi) stable multiply Massive (quasi) stable multiply charged particles (eg Hcharged particles (eg H++ ++ from from L-R symmetric models)L-R symmetric models)

• Q-ball type objects (aggregates Q-ball type objects (aggregates of squarks , sleptons, Higgs of squarks , sleptons, Higgs fields)fields)

• ETC.ETC.

hep-ph/9707376hep-ph/9707376


Radiation Environment Around VELORadiation Environment Around VELODose Dose


Hadron FluxesHadron Fluxes

Charged hadron flux x=0Charged hadron flux x=0 Neutron flux, x=0Neutron flux, x=0

~1011 neutrons/cm2 each year ~1010 hadrons /cm2 each year


Radiation Resistance of CR39/LexanRadiation Resistance of CR39/Lexan

• Results obtained from an expt. at the D0 intersection regions at FNALResults obtained from an expt. at the D0 intersection regions at FNAL– Phys. Rev. Lett. 59, p2523, 1987Phys. Rev. Lett. 59, p2523, 1987..

• Chemistry of rad. sensitivity of CR-39 polymers has been studiedChemistry of rad. sensitivity of CR-39 polymers has been studied– J. Electrochem. Soc., p811, 1982.J. Electrochem. Soc., p811, 1982.

• Track etch detectors can have the following radiation toleranceTrack etch detectors can have the following radiation tolerance– CR39 2MRads - Rodyne(lexan) 200 Mrad - UG-5 glass 1000 Mrads.CR39 2MRads - Rodyne(lexan) 200 Mrad - UG-5 glass 1000 Mrads.

• Radiation level at LHCb – 1.4 m from the IP is low enough to deploy Radiation level at LHCb – 1.4 m from the IP is low enough to deploy CR39 for several years without problems. We expect to change plastic CR39 for several years without problems. We expect to change plastic 112 times per year.2 times per year.


The LHCb IP – the VELO regionThe LHCb IP – the VELO region

Material in the VELO Region (1)Material in the VELO Region (1)

+ COVER

1.2 m


Material in the VELO Region (2)Material in the VELO Region (2)

• Distribution of material in the LHCb vertex region (in radiation lengths) Distribution of material in the LHCb vertex region (in radiation lengths) as described by the LHCb simulation program GAUSS.as described by the LHCb simulation program GAUSS.


A GEANT-4 Simulation of the A GEANT-4 Simulation of the MonopoleMonopole

• GEANT4 simulation for the monopole prepared to work within the GEANT4 simulation for the monopole prepared to work within the LHCb GAUSS simulation package (many thanks to Gloria Corti of LHCb GAUSS simulation package (many thanks to Gloria Corti of LHCb for her assistance here)LHCb for her assistance here)

• Results cross-checked against a GEANT3 monopole simulation Results cross-checked against a GEANT3 monopole simulation (CDF: Bauer et al, Submitted to Elsevier Science) and stand alone (CDF: Bauer et al, Submitted to Elsevier Science) and stand alone code.code.

• This package allows us to:This package allows us to:– Track a monopole or dyon Track a monopole or dyon – Simulate ionization energy lossSimulate ionization energy loss– Simulate multiple scatteringSimulate multiple scattering

• If produced inside a particle detectors a monopole or dyon would be If produced inside a particle detectors a monopole or dyon would be revealed by its unique characteristics:revealed by its unique characteristics:– Monopoles would accelerate along magnetic field lineMonopoles would accelerate along magnetic field line– Monopole would have extremely high ionization compared to Monopole would have extremely high ionization compared to

charged particles.charged particles.


Tracking Tracking • Electric-magnetic duality of ME gives a generalized Lorentz force for Electric-magnetic duality of ME gives a generalized Lorentz force for

particles carrying arbitrary electric charge e and magnetic charge g:particles carrying arbitrary electric charge e and magnetic charge g:

• This describes the motion of a dyon, setting electric charge to zero This describes the motion of a dyon, setting electric charge to zero gives a differential equation describing the motion of a monopole in gives a differential equation describing the motion of a monopole in a magnetic field.a magnetic field.

• Qualitatively the monopole in a magnetic field behaves like an Qualitatively the monopole in a magnetic field behaves like an electron in an electric field.electron in an electric field.


An Example of Monopole Pair An Example of Monopole Pair Production in MOEDAL/LHCbProduction in MOEDAL/LHCb

MMPP

One monopole Hits MOEDAL

MOEDALThe other monopole hits the pole face of the LHCb dipole magnet


Energy loss Energy loss • The net effect is to replace ze by ngThe net effect is to replace ze by ng in the Bethe Bloch formula: in the Bethe Bloch formula:

• Similarly the mutiple scattering of a monopole has the factor of ze Similarly the mutiple scattering of a monopole has the factor of ze replaced by ngreplaced by ng

Monopole energyMonopole energyloss increases withloss increases withvelocity velocity

A highly relativistic A highly relativistic monopole ionizes monopole ionizes up to 4700 times moreup to 4700 times morethan that of a proton than that of a proton


Monopole Pair ProductionMonopole Pair Production

• On average the acceptance of monopole pairs (in which at least one of the monopole is detected) On average the acceptance of monopole pairs (in which at least one of the monopole is detected) is ~80% over most of the detectable monopole mass range (assume pairs produced isotropically is ~80% over most of the detectable monopole mass range (assume pairs produced isotropically in the centre-of-mass system)in the centre-of-mass system)

• Acceptance of monopole detector plastic covering both pole faces of the LHCb dipole magnet is Acceptance of monopole detector plastic covering both pole faces of the LHCb dipole magnet is approximately a factor of 10 smaller that that of MOEDAL over most of the detectable mass rangeapproximately a factor of 10 smaller that that of MOEDAL over most of the detectable mass range

Acceptance for a single monopoleIsotropically produced.


Limits After a Year at 2 x 10Limits After a Year at 2 x 103232 cm cm-2-2 s s-1-1

MOEDAL (95% CL)

Prel

imin

ary


Estimating Backgrounds with GEANT4Estimating Backgrounds with GEANT4• Backgrounds due to spallation products in the detector and environs – Backgrounds due to spallation products in the detector and environs –

etch pits from hadronic backgrounds.etch pits from hadronic backgrounds.• We are using GEANT4 to provide extra detailed information on the size of We are using GEANT4 to provide extra detailed information on the size of

the potential background.the potential background.• It is expected that backgrounds will be extremely small due to the uniquess It is expected that backgrounds will be extremely small due to the uniquess

of a monopole signal (>3 precisely aligned pairs of etch pits, consistent of a monopole signal (>3 precisely aligned pairs of etch pits, consistent with a monopole charge, pointing to the IP within ~1 cm)with a monopole charge, pointing to the IP within ~1 cm)

• Use Geant4 Hadronic Physics lists: Use Geant4 Hadronic Physics lists: http://cmsdoc.cern.ch/~hpw/GHAD/HomePage/ In particular:In particular:– High energy calorimetry (for spallation products produced by high energy High energy calorimetry (for spallation products produced by high energy

particles from interactions)particles from interactions)– Low energy dosimetry (to look at neutron produced damage)Low energy dosimetry (to look at neutron produced damage)

• The high energy calorimetry code uses:The high energy calorimetry code uses: ““The second physics list, The second physics list, QGSP -- -- theory driven modeling for the reactions of energetic pions, kaons, and nucleons. It theory driven modeling for the reactions of energetic pions, kaons, and nucleons. It employs quark gluon string model for the 'punch-through' interactions of the employs quark gluon string model for the 'punch-through' interactions of the projectile with a nucleus, the string excitation cross-sections being calculated in projectile with a nucleus, the string excitation cross-sections being calculated in quasi-eikonal approximation. A pre-equilibrium decay model with an extensive quasi-eikonal approximation. A pre-equilibrium decay model with an extensive evaporation phase to model the behavior of the nucleus 'after the punch'. It uses evaporation phase to model the behavior of the nucleus 'after the punch'. It uses current best pion cross-section.” current best pion cross-section.”

• Initial estimates indicate that the background from this source is negligible Initial estimates indicate that the background from this source is negligible – we are currently working on final numbers for this background level. – we are currently working on final numbers for this background level.

http://cmsdoc.cern.ch/~hpw/GHAD/HomePage/

http://cmsdoc.cern.ch/~hpw/GHAD/HomePage/

http://cmsdoc.cern.ch/~hpw/GHAD/HomePage/geant4.5.2/lists/QGSP/index.html


The Conceptual Design of The Conceptual Design of MOEDALMOEDAL

• In June of 2001 the LHCb collaboration completed the LHCb In June of 2001 the LHCb collaboration completed the LHCb “VELO” (VErtex Locator) TDR that incorporated the latest LHCb “VELO” (VErtex Locator) TDR that incorporated the latest LHCb vertex region design.vertex region design.

• We have been tracking developments in the VELO region since We have been tracking developments in the VELO region since that time.that time.

• The LHCb vertex region design is now reasonably mature Thus The LHCb vertex region design is now reasonably mature Thus we have begun the design of the final MOEDAL detector.we have begun the design of the final MOEDAL detector.

• This design presented here is conceptual only and must be This design presented here is conceptual only and must be refined in consultation with the LHCb collaboration and CERN TIS refined in consultation with the LHCb collaboration and CERN TIS group.group.

• Thus we expect this design to evolve.Thus we expect this design to evolve.• Obviously the LHCb collaboration must be completely happy with Obviously the LHCb collaboration must be completely happy with

the final product which must also satisfy CERN safety criteria,.the final product which must also satisfy CERN safety criteria,.


The Conceptual Design of MOEDAL(1)

Detector is a housed in geodisic segments.Detector is a housed in geodisic segments.To allow fast access (within an hour) to VELO. To allow fast access (within an hour) to VELO. The detector opens lake a “ladybird’s wings”. The detector opens lake a “ladybird’s wings”.

Support from roof only in initial designSupport from roof only in initial design

Radius of sphere 1.4m


• Light aluminium frame containing Light aluminium frame containing five plastic sheets per triangle five plastic sheets per triangle element (Lexan-CR39-Lexan-element (Lexan-CR39-Lexan-CR39-CR39-lexan). Total CR39-CR39-lexan). Total thickness ~ 5 mm.thickness ~ 5 mm.

• Alignment of monopole track within Alignment of monopole track within the module ~10 microns (using the module ~10 microns (using dowel pins)dowel pins)

• All triangular elements do NOT All triangular elements do NOT have to be installed. The design have to be installed. The design allows for access “panels” to LHCB allows for access “panels” to LHCB vertex vacuum region.vertex vacuum region.

• Frame holds plastic so that tracks Frame holds plastic so that tracks are as normal as possible to the are as normal as possible to the plastic, and racks reconstructed plastic, and racks reconstructed can be pointed to the interaction can be pointed to the interaction point two within ~1 cmpoint two within ~1 cm

The Conceptual Design of MOEDAL(2)The Conceptual Design of MOEDAL(2)


Monitoring MOEDAL PerformanceMonitoring MOEDAL Performance

• We have devised a procedure to check that the experiment is We have devised a procedure to check that the experiment is working – particularly in the high radiation environments of the working – particularly in the high radiation environments of the LHCLHC

• We propose to irradiate small areas of the CR39 detectors with We propose to irradiate small areas of the CR39 detectors with ions prior to deployment.ions prior to deployment.

• For example we would use:For example we would use:– Relativistic Fe ions for CR-39 (Z/b ~30)Relativistic Fe ions for CR-39 (Z/b ~30)– Gold ions for Rodyne/lexan (Z/b ~90)Gold ions for Rodyne/lexan (Z/b ~90)

• Only if these “fake” monopole tracks in individual sheets give Only if these “fake” monopole tracks in individual sheets give detectable holes with the “ammonia technique” after etching will detectable holes with the “ammonia technique” after etching will the detector be deemed to be working.the detector be deemed to be working.


Towards the Technical Proposal(1)• A priority for the next 6 months of ‘05 - as the VELO region design A priority for the next 6 months of ‘05 - as the VELO region design

is now stable - is to work with LHCb-VELO region engineers to is now stable - is to work with LHCb-VELO region engineers to modify mounting scheme of MOEDAL to be compatible with LHCb, modify mounting scheme of MOEDAL to be compatible with LHCb, specifically:specifically:

– There should be no mechanical contact with the VELO vesselThere should be no mechanical contact with the VELO vessel– The MoEDAL detector should be able to be moved within a few The MoEDAL detector should be able to be moved within a few

hours at most to allow quick access to the VELO region hours at most to allow quick access to the VELO region – The MoEDAL detector should be moveable completely within 6 The MoEDAL detector should be moveable completely within 6

hours to allow work on the VELO region where crane access is hours to allow work on the VELO region where crane access is required.required.

• Demonstrate the deployment of MOEDAL by building a model of the Demonstrate the deployment of MOEDAL by building a model of the MoEDAL frame and deploying it around the model of the VELO MoEDAL frame and deploying it around the model of the VELO regionregion

• We assume that LHCb collaboration would have to formally approve We assume that LHCb collaboration would have to formally approve of the MoEDAL mounting scheme and operating procedure before of the MoEDAL mounting scheme and operating procedure before any approval for MoEDAL can be givenany approval for MoEDAL can be given

• The plans for the installation /staging of MoEDAL in the VELO region The plans for the installation /staging of MoEDAL in the VELO region will also be discussed closely with LHCb, obviously this schedule will also be discussed closely with LHCb, obviously this schedule must be completely compatible with LHCb plans.must be completely compatible with LHCb plans.


• Work with CERN TIS group to finalize design of MOEDAL detector (in Work with CERN TIS group to finalize design of MOEDAL detector (in progress). Particular areas of investigation are:progress). Particular areas of investigation are:

• Activation: Detectors already sent to CERN for activation studies Activation: Detectors already sent to CERN for activation studies (Aluminium & plastic are not expected to be problematic)(Aluminium & plastic are not expected to be problematic)

• Safety (access for fire control, flammability, etc.) Safety (access for fire control, flammability, etc.)

• We plan to submit the MoEDAL design to CERN TIS for inspection We plan to submit the MoEDAL design to CERN TIS for inspection after the MOEDAL design is stable – we expect this to be in the after the MOEDAL design is stable – we expect this to be in the summer of 2005. although flammability studies (of the basic plastic summer of 2005. although flammability studies (of the basic plastic detector element) can start within a month or two.detector element) can start within a month or two.

• Finalize picture of the sensitivity of detectors to radiation in the LHCb Finalize picture of the sensitivity of detectors to radiation in the LHCb region using GEANT4 equipped to study spallation products . This work region using GEANT4 equipped to study spallation products . This work is in progress and it is expected to be finished by the summer of 2005.is in progress and it is expected to be finished by the summer of 2005.

• Perform detailed MC studies - using existing program, full detector Perform detailed MC studies - using existing program, full detector implmentation and latest material distribution - of monopole acceptance implmentation and latest material distribution - of monopole acceptance using the now available GEANT4/GAUSS monopole simulation. The using the now available GEANT4/GAUSS monopole simulation. The work is in progress and is expected to be completed by spring 2005.work is in progress and is expected to be completed by spring 2005.

• Include studies of other physics aims such as Q-ball detection and the Include studies of other physics aims such as Q-ball detection and the detection of heavily ionizing conventionally charged Exotics This work detection of heavily ionizing conventionally charged Exotics This work has started and will be completed by fall 2005. has started and will be completed by fall 2005.

• Produce first version of the MOEDAL TP by the end of the 2005.Produce first version of the MOEDAL TP by the end of the 2005.

Towards the Technical Proposal (2)


Post TP Considerations (1)• We estimate that the cost of the MOEDAL mechanical assembly and We estimate that the cost of the MOEDAL mechanical assembly and

deployment will be less than 80kCHF (re: UofA machining @ 5 CHF/hr)deployment will be less than 80kCHF (re: UofA machining @ 5 CHF/hr)• The area of plastic used is estimated to be 12mThe area of plastic used is estimated to be 12m22 x 5 layers (3- CR39 & 2- x 5 layers (3- CR39 & 2-

Lexan) costing ~20K CHF. Expect to change plastic Lexan) costing ~20K CHF. Expect to change plastic twice per yr. twice per yr.• The MoEDAL groups have established expertise and infrastructure. Eg:The MoEDAL groups have established expertise and infrastructure. Eg:

– The Alberta group has extensive mechanical design & construction The Alberta group has extensive mechanical design & construction experience (eg: machining of ATLAS HEC, design of HEC construction experience (eg: machining of ATLAS HEC, design of HEC construction jigs etc.) jigs etc.)

– The Bologna Group has extensive experience with analyzing plastic and The Bologna Group has extensive experience with analyzing plastic and extensive etching, scanning infrastructure (eg, for MACRO & SLIM)extensive etching, scanning infrastructure (eg, for MACRO & SLIM)

– The Cincinnati group (KK) has extensive experience with analyzing The Cincinnati group (KK) has extensive experience with analyzing plastic and has some etching and scanning capability (Eg KK group at plastic and has some etching and scanning capability (Eg KK group at Harvard analyzed MODAL & OPAL-monopole plastic, etc.)Harvard analyzed MODAL & OPAL-monopole plastic, etc.)

– The Alberta, Bologna & Cincinatti groups have established expertise in The Alberta, Bologna & Cincinatti groups have established expertise in perfoming direct searches for monopoles at accelerators LEP (L6), LEP perfoming direct searches for monopoles at accelerators LEP (L6), LEP (OPAL), the Tevatron, KEK, etc.(OPAL), the Tevatron, KEK, etc.

– The Montreal Group has extensive experience in the effects of radiation The Montreal Group has extensive experience in the effects of radiation radiation damage (eg Claude Leroy was an ATLAS convenor in this area)radiation damage (eg Claude Leroy was an ATLAS convenor in this area)

– All the above groups have extensive experience with MC simulation/ All the above groups have extensive experience with MC simulation/ physics analysis (Eg GEANT3/4 calculations at LEP, ATLAS, CLEO, physics analysis (Eg GEANT3/4 calculations at LEP, ATLAS, CLEO, MACRO, SLIM etc.MACRO, SLIM etc.


Post TP Considerations (2)

• Availability of main funding requirement is subject to approval of Availability of main funding requirement is subject to approval of MoEDAL TPMoEDAL TP

• However, a substantial amount of the infrastructure required to However, a substantial amount of the infrastructure required to perform the experiment already existsperform the experiment already exists

• The detector is simple and completely passive. Construction is The detector is simple and completely passive. Construction is envisaged to start in 2006, and take between 8envisaged to start in 2006, and take between 8 10 months 10 months integrated time. The envelope to be determined by funding availabilityintegrated time. The envelope to be determined by funding availability

• The installation time required is (in principle) short (around a month). The installation time required is (in principle) short (around a month). We expect that the construction schedule will be modified to meet the We expect that the construction schedule will be modified to meet the requirements of LHCb.requirements of LHCb.

• The MoEDAL is much simpler than the usual collider detector. The MoEDAL is much simpler than the usual collider detector. However, there are still major challenges to face before we can see However, there are still major challenges to face before we can see physics from it.physics from it.

the moedal experiment: a progress report

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