tungsten hcal simulation studies
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Tungsten HCAL simulation studies. Peter Speckmayer CLIC 09 12 – 16 October 2009. considerations for HCAL depth and material. shower leakage worsens energy resolution to reduce leakage: deeper calorimeter denser calorimeter (more interaction lengths) - PowerPoint PPT PresentationTRANSCRIPT
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CLIC09, Peter Speckmayer 1
Tungsten HCAL simulation studies
Peter SpeckmayerCLIC 09
12 – 16 October 2009
15/10/2009
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CLIC09, Peter Speckmayer 2
considerations for HCAL depth and materialshower leakage worsens energy resolution
to reduce leakage:deeper calorimeterdenser calorimeter (more interaction lengths)
depth limited by feasible coil size:larger coil with smaller B-fieldlarger B-field with smaller coil
depth limited by tracker size:larger tracker better p-resolution
15/10/2009
IP beam
COIL
HCAL
Tracker
ECAL
Vertex
Barrel Endcaphere would be a tail-catcher
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CLIC09, Peter Speckmayer 3
HCAL absorber material which material for the absorber?
steel, tungsten, ... ?
Tungstenexpensive!more contained showers (compared to Fe) with the same
HCAL geometrical depth less leakagesmaller shower diameter better separation of showers
(probably good for particle flow)
final goal good energy resolution with whole detector
15/10/2009
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CLIC09, Peter Speckmayer 4
Energy reconstruction with neuronal network
15/10/2009
shorter HCAL more leakage worse resolution
numbers denote HCAL length inunits of interaction lengths
~40 λ
5 mm scintillator, 2.5 mm G10
(information from fine granularity of calorimeter not used traditional approach)-variables describe shower shape and size and energy-train NN with pion energy
steel
tungsten
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CLIC09, Peter Speckmayer 5
Tail-catcher
15/10/2009
tungsten
coil thickness: 2 λzero λ tail-catcher implies no active material after the coilhaving some tail-catcher (1 λ) improves resolutioneffect of bigger tail-catcher is small
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CLIC09, Peter Speckmayer 6
Tungsten HCALTungsten used in ECALs
typically ~1λ deepNo experience with tungsten HCALs
~4 – 9 λ deep
simulation of tungsten not validatedno MC/data comparisonsno validation for high granularity
If tungsten is used have to be sure, that energy resolution of whole detector is better (PFA)
15/10/2009
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CLIC09, Peter Speckmayer 7
physics-list differences (Geant4)simulations of pion showers in block of tungsten
tungsten, QGSP_BERT tungsten, QGSP_BERT_HP
Evisible/EMC
transition regions of modelswith HP (high precision neutron tracking) enabled much less energy deposit by ionization
which one can we trust more?
15/10/2009
Evisible/EMC
in QGSP_BERT more n produced, more n captured ~8MeV of photons each accounts for difference
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CLIC09, Peter Speckmayer 8
lead, QGSP_BERTtungsten, QGSP_BERT_HP
similar widths of lead and tungsten, when HP is used
“feeling” says: this is more trustworthy
lead simulations for hadrons are better validated
15/10/2009
Evisible/EMCEvisible/EMC
physics-list differences (Geant4)simulations of pion showers in block of lead/tungsten
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CLIC09, Peter Speckmayer 9
Effect of physics list on predicted resolution
15/10/2009
5 mm scintillator, 2.5 mm G10
~10-15% improvement (at 40 GeV)
why: n are captured farther away from shower core “halo” produced which reduces reconstruction performance. removing halo (with HP n tracking)
less energy deposited by ionization, but ... Improved resolution!
considerable effectbut: perfect readout assumed
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CLIC09, Peter Speckmayer 10
Further reason for validation
Time structure of signal broadened by n-contenttime stamping
used to separate signal/background on a time basis (slow) n-content smears out energy deposits in
calorimeters know time-structure of n-content to set
requirements for time stampingdependent on active material (e.g. scintillator,
gas)measurements necessary15/10/2009
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CLIC09, Peter Speckmayer 11
Particle flow results so farComparison of around 8 ½ interaction lengths of HCAL with Fe and WW delivers comparable resolution to Feno optimization of the PFA for W done
15/10/2009
Angela Lucaci-Timoce
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CLIC09, Peter Speckmayer 12
Tungsten HCAL PrototypeWhat can we learn?Physics performance
Verify simulations (resolution, shower shapes, ...)Include realistic noise levels (read-out, neutrons,
...)
Tungsten plate production processTest production of large thin platesFeasibility of needed flatnessMachining of tungsten platesBolting, cutouts
15/10/2009
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CLIC09, Peter Speckmayer 13
Longitudinal shower size
15/10/2009
C. Grefe
95% contained energy → ~40 layers (~4.8 λ)
95%
12 mm tungsten + 5 mm Scint + 2.5 G10
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CLIC09, Peter Speckmayer 14
Lateral shower size
15/10/2009
C. Grefe
95% contained energy → ~40 cm radius
95%
12 mm tungsten + 5 mm Scint + 2.5 G10
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CLIC09, Peter Speckmayer 15
Longitudinal shower sizes: tungsten + micromegas
15/10/2009
J. Blaha
95%
11 mm tungsten + micromegas
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CLIC09, Peter Speckmayer 16
Lateral shower sizes: tungsten + micromegas
15/10/2009
J. Blaha
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CLIC09, Peter Speckmayer 17
more about prototype
see following talk by W.Klempt
15/10/2009
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CLIC09, Peter Speckmayer 18
Conclusions & OutlookFrom tungsten simulations:
8-9 λ ’s ECAL+HCAL seems sufficient up to 300 GeV (pions)
~10-15 mm W absorber optimaltail catcher usefulchoice of GEANT4 physics list important (different
results for W simulations)Particle Flow algorithm W and Fe first results are
comparable will be extended
From future prototype results:feed back prototype to G4-team
15/10/2009
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CLIC09, Peter Speckmayer 19
backup
15/10/2009
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CLIC09, Peter Speckmayer 20
Tail-catcher
15/10/2009
coil thickness: 2 λzero λ tail-catcher implies no active material after the coilhaving some tail-catcher (1 λ) improves resolutioneffect of bigger tail-catcher is small
tungsten steel