Dominik Dannheim (CERN), André Sailer (HU Berlin / CERN)

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Beam-induced backgrounds in the CLIC detector models ALCPG Workshop 19.-23. March 2011 Eugene, Oregon. Dominik Dannheim (CERN), André Sailer (HU Berlin / CERN). Outline. CLIC_ILD_CDR and CLIC_SiD_CDR detector models Beam-induced backgrounds at 3 TeV CLIC machine: - PowerPoint PPT Presentation

Transcript of Dominik Dannheim (CERN), André Sailer (HU Berlin / CERN)

PowerPoint Presentation

Dominik Dannheim (CERN), Andr Sailer (HU Berlin / CERN)Beam-induced backgrounds in the CLIC detector models

ALCPG Workshop19.-23. March 2011Eugene, Oregon

1ALCPG March 20112OutlineCLIC_ILD_CDR and CLIC_SiD_CDR detector models

Beam-induced backgrounds at 3 TeV CLIC machine:Incoherent e+e- pairs hadronsOther sources

Visible energy and background occupancies

Radiation damage:Non-ionizing energy lossTotal ionizing dose

Summary/conclusions

Beam-induced backgrounds in the CLIC detector models2

ALCPG March 20113CLIC_ILD_CDR detector modelBeam-induced backgrounds in the CLIC detector modelsCLIC_ILD_CDR simulation model:Based on ILC-ILDscaled and optimized for 3 TeV CLICReduction of backscatters:~pointing conical beam pipe (=6.7o)4 Tesla B-fieldHCal outer radius: 3.3 m (7.5 i)3 pixel double-layers for barrel vertexdetector, 20 x 20 m2 pixels, R31 mm TPC as main tracker + silicon envelope

CLIC parameters:s up to 3 TeV312 bx per train, 0.5 ns spaced,50 Hz train-repetition rate20 mrad crossing angleCross-sections in fwd regions highfor many physics and BG processes3ALCPG March 20114CLIC_SiD_CDR detector modelBased on ILC-SiD, scaled and optimized for 3 TeV CLIC parametersSimilar acceptance and performance as CLIC_ILD_CDRSimilar reduction of backscatters: pointing conical beam pipe (=6.7o)Larger B-field (5 Tesla), HCal outer radius: 2.7 m (7.5 i)5 pixel single layers (20 x 20 m2) for barrel vertex detector, R27 mmAll-silicon trackerBeam-induced backgrounds in the CLIC detector models

Forward region:4

ALCPG March 20115e+e- pairs at 3 TeVBeam-induced backgrounds in the CLIC detector modelse+e- pairs at s=3 TeV simulated with GUINEAPIG (D. Schulte) 6 x 108 coherent particles / bxSpectrum falls very steeply with Acceptance BeamCal 5.73o6ALCPG March 20117Other sources of machine-induced backgroundsBeam-induced backgrounds in the CLIC detector modelsBeam-halo muons2x104 s per train expectedAlmost parallel to beam axisrate falls only slowly with radiusdeflection expensive (magnetized iron),under studyMain source of background for outer trackerin particular challenging for TPC in CLIC_ILDand for calorimeters, studies ongoing

Incoherent synchrotron radiation from BDSNo direct hits by design of collimator systemHowever: possibly sizeable rate of low-energy particles bouncing along beam-delivery systemto be studied in more detail

Same production mechanism as incoherent e+e- pairs~same shape as for e+e- pairs, but rate is reduced by 1/104

Will focus on incoherent pairs + hadrons for rest of this talk

Beam-halo muons in CLIC_ILD TPC:(1 bunch train=312 bx)7ALCPG March 20118Visible energy from hadrons - resultsBeam-induced backgrounds in the CLIC detector models==================================================Pythia 2010 sample (D. Schulte) 3.2 events / bx==================================================Section CLIC_ILD_CDR CLIC_SiD_CDR Evis/bx [GeV] Evis/bx [GeV] ==================================================no cuts 1365.2 1365.2--------------------------------------------------LUMI-CAL 101.5 120.2 --------------------------------------------------CAL-Endcap 35.4 45.3CAL-Barrel 3.6 4.4 CAL-all 37.8 47.5==================================================Up to 15 TeV / bunch train in calorimetersLarger values for CLIC_SiD_CDR, due to more compact layout

Event overlay challenging for simulation and reconstructionEstimate visible energy per subdetector by applying pT and -acceptance cuts to MC true particles8ALCPG March 20119OccupanciesBeam-induced backgrounds in the CLIC detector modelsTwo independent simulations to estimate occupancies:

Standalone fast simulation in C++Tracks final-state particles from Monte Carlo generatorCalculates helix in B-field for each particleFollows particles along helix (no interactions take place)Projects particle tracks on horizontal/vertical slicesTakes into account multiple hits from curlersUsed for all detector regions and both CLIC_ILD_CDR and CLIC_SiD_CDRMC statistics: incoherent pairs: 312 bx, hadrons: 2100 bx

Full Geant-4 simulation of detector response:Based on Mokka/SLICTakes into account interactions and decaysIncludes backscatters from very forward regionHas been used to optimize detector design, seeAndr Sailers talk at ECFA-CLIC-ILC Joint Meeting (Oct. 2010)Results for limited number of scoring planes in CLIC_ILD_CDRMC statistics: incoherent pairs: 100 bx, hadrons: 900 bx

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ALCPG March 201110Cylindrical occupancies from pairsBeam-induced backgrounds in the CLIC detector modelsTPCResults obtained with fast simulation and for radial projectionPair background large at small radii, falls steeply with radiusSIT2SIT1VXBFTDPixelFTDStrips10

ALCPG March 201111Cylindrical occupancies from hadronsBeam-induced backgrounds in the CLIC detector modelsTPChadrons fall less steeply with radius than pairsdominates occupancies at large radiiSIT2SIT1VXBFTDPixelFTDStrips11

ALCPG March 201112Barrel occupancies in CLIC_ILD_CDR vs. radiusBeam-induced backgrounds in the CLIC detector modelsIncoherent pairs dominate at small radiushadrons dominate at larger radiiGood agreement between full and fast simulationUp to ~1.5 hits / mm2 / bunch train in innermost vertex layer

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ALCPG March 201113Disc occupancies from pairsBeam-induced backgrounds in the CLIC detector modelsTPCResults obtained for projection on xy-plane (discs)Pair background large at small radii, falls steeply with radiusSIT2SIT1VXBFTDPixelFTDStrips13

ALCPG March 201114Disc occupancies from hadronsBeam-induced backgrounds in the CLIC detector modelsTPChadrons fall less steeply with radius than pairsdominates occupancies at large radiiSIT2SIT1VXBFTDPixelFTDStrips14

ALCPG March 201115Forward occupancies in CLIC_ILD_CDR vs. radiusBeam-induced backgrounds in the CLIC detector modelsIncoherent pairs dominate at small radiushadrons dominate at larger radiiMore hits in full simulation: backscatters become important in fwd regionUp to ~2 hits / mm2 / bunch train in lower part of first vertex disc

Projections on xy-plane15ALCPG March 201116Non-ionizing energy lossBeam-induced backgrounds in the CLIC detector modelsEstimate radiation damage (in silicon) from non-ionizing energy loss (NIEL):

Simulation based on setups used for estimating occupanciesScale hits with displacement-damage factor 1-MeV-neutron equivalent fluenceUse energy-dependent tabulated scaling factors for Silicon from:http://sesam.desy.de/members/gunnar/Si-dfuncs.html To obtain expected fluence per year, assume:1 year =100 days effective runtime = 100*24*60*60 seconds; 50*312 bx per second

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ALCPG March 201117NIEL (cylindrical projection) from pairsBeam-induced backgrounds in the CLIC detector modelsTPCSimilar observations as for occupancies: pair-background fallssteeply with radiusSIT2SIT1VXBFTDPixelFTDStrips17

ALCPG March 201118NIEL (cylindrical projection) from hadronsBeam-induced backgrounds in the CLIC detector modelsTPCNIEL for hadrons falls less steeply with radius and also dominatesalready at smaller radii, due to larger damage factorsSIT2SIT1VXBFTDPixelFTDStrips18

ALCPG March 201119NIEL in CLIC_ILD_CDR barrel vs. radiusBeam-induced backgrounds in the CLIC detector modelshadrons dominate at all radii, due to larger damage factorsGood agreement between full and fast simulation for hadronsMore damage in full simulation for incoh. pairs due to backscattered neutronsMaximum flux in innermost vertex layers: ~1010 1-MeV-n-equiv. / year,i.e. 4 orders of magnitude below LHC levels19ALCPG March 201120NIEL in CLIC_ILD_CDR forward region vs. radiusBeam-induced backgrounds in the CLIC detector modelshadrons dominate NIEL, due to larger damage factorsMaximum flux in lower part of 1st forward disc: ~1010 1-MeV-n-equiv. / year

Projections on xy-plane20ALCPG March 201121Total ionizing dose in vertex detectorBeam-induced backgrounds in the CLIC detector modelsEstimate radiation damage from total ionizing dose (TID):Use only the setup from full Geant-4 simulationSum up energy release in silicon, as given by Geant-4Results obtained for vtx layers in CLIC_ILD_CDR

Up to ~100 Gy / yr in innermost barrel vertex layersUp to ~20 Gy / yr on inner side of 1st forward vertex pixel discFor comparison: ATLAS innermost pixel layer ~160 kGy / yr21ALCPG March 201122NIEL and TID in BeamCalBeam-induced backgrounds in the CLIC detector models

NIEL in 5th layer of BeamCal:

TID in 5th layer of BeamCal:Up to 1 MGy / yrUp to ~1013 1-MeV-n-equ. / cm2 / yrFull Geant-4 simulation of incoherent pairs for BeamCal in CLIC_ILD_CDRObtained estimates for NIEL and TID per yearcf. also A. Sailers presentation at FCAL collab. workshop in Oct. 201022ALCPG March 201123Summary/ConclusionsBeam-induced backgrounds in the CLIC detector modelsLarge amount of energy and high rates expected from backgrounds:Evis~12-15 TeV / bunch train in barrel and EC calorimetersOccupancies up to ~2 hits / mm2 / bunch train in 1st vertex layers

Major challenge for detector readout and reconstruction software

Work is ongoing to optimize overlay and reconstruction algorithms,see Jan Strubes talk in yesterdays Physics session

First estimate of expected radiation damages from selected sources:NIEL: 1010 1-MeV-n-equ. / yr in 1st vertex layers,up to ~1013 1-MeV-n-equ. / yr in BeamCalTID: up to 100 Gy / yr in 1st vertex layers,up to 1 MGy / yr in BeamCal23ALCPG March 201124Backup slidesBeam-induced backgrounds in the CLIC detector models24ALCPG March 201125Visible energy from hadronsSimple estimation of energy releases in calorimeters:Define -acceptance for sub-detectors