Muon identification with realistic detector layout

1
Muon identification with realistic detector
layout
10th CBM Collaboration Meeting

• Anna Kiseleva

2
Outline

• Realistic segmentation of the MuCh
• Invariant mass spectra for LMVM and charmonium
• Time of flight measurements
• J/? and ?' at 35 AGeV
• Conclusions
• Next steps

3
Simulations

• Signals (Pluto, multiplicities from HSD)
• ?, ?, f, ? and ?Dalitz
• J/?, ?'
• Background (UrQMD)
• central AuAu at 25 and 35 AGeV (charmonium)
• Statistics for background
• 20k events

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Detector parameters

• STS
• 6 strip detectors
• MuCh
• 15 (18) layers with realistic segmentation
• Layer 12 ToF RPC - 80 ps time resolution
• ToF at 10 m
• 0.7 cm position resolution
• 80 ps time resolution

STS MuCh
ToF
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Muon Chambers (MuCh) GEANT3
20 20 20 30 35 cm
hard track
Fe Fe Fe Fe Fe
314 cm
soft track
5 cm
102.5 cm
0 cm
6
Muon system at CBM
Sergey Belogurov
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Muon system at CBM
Sergey Belogurov
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Segmentation of MuCh
See talk of Mikhail Ryzhinskiy
layer Nr.1
max 1 hit/(cm2event)
min pad 1.4 ? 2.8 mm2
layer Nr.15
max 0.01 hit/(cm2event)
max pad 44.8 ? 44.8 mm2
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Results
? background
signals ? ? ? ? ? f ? ? ? ?Dalitz
Central AuAu collision at 25 AGeV
S/B Efficiency
Mass ratio ()
resolution

(MeV) ? 0.08 3.7 12
4.7 10 f 0.03 6
19 8.3 12 ? 0.001
2.7 9 3.8 J/? 7
16 36 20 24 ?'
0.09 19 41 28
Accepted signals (MC)
? background
signals ? J/? ? ?'
LMVM 4STS 15(12)MuCh charm 4STS
18MuCh smearing 100µm
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Reconstructed ?0 hhhs pairs
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Reconstructed charmonium
J/? ?'
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Background suppression for J/?(?')
efficiency
central AuAu collisions at 25 AGeV
Nreco bg pairs event J/? (1.210-6) ?' (1.910-9)
without cuts 210-4 16 18
pt gt 1.2 GeV/c a gt 20 210-7 11 17
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Reconstructed background
large MuCh
µ p ? ghost
particle ID 70 true hits
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Reconstructed background
compact MuCh
hard tracks soft
tracks
µ (106 MeV) p (140 MeV) ? (498 MeV) p
(938 MeV) ghost
particle ID 70 true hits
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Mass calculation
(L, t) ? ßToF
layer Nr.12 ToF RPC
ToF
(L, t) ? ßMuCh
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Mass distributions PSTSvs.m2
ToF at MuCh layer Nr.12
ToF at 10m
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Mass distributions PSTSvs.m2
soft tracks
ToF at MuCh layer Nr.12
signal µ
bg µ
p
K
p
ghost
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Mass distributions PSTSvs.m2
hard tracks
ToF at MuCh layer Nr.12
signal µ
bg µ
p
K
p
ghost
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Mass distributions c
hard tracks
rescaled
ToF at MuCh layer Nr.12
signal µ
bg µ
p
K
p
ghost
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Mass distributions PSTSvs.m2
hard tracks
cut at MuCh ToF
ToF at 10 m
signal µ
bg µ
p
K
p
ghost
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Reconstructed background
after cuts
hard tracks soft
tracks
µ (106 MeV) p (140 MeV) ? (498 MeV) p
(938 MeV) ghost
particle ID 70 true hits
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Results hh pairs
---------- cuts ----------
1 2
12 layer Nr.12 ToF at
10m ToF RPC
without cuts
S/B ratio
? f ? f
0.21 0.08 1.2 2.5
0.11 0.05 1.6 3.4
0.09 0.03 2.0 4.1
0.17 0.06 1.5 3.0
Efficiency ()
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Results hs pairs
hard tracks cuts at layer Nr.12 ToF RPC ToF
at 10m soft tracks cuts at layer Nr.12 ToF RPC
without cuts
S/B ratio
? f ? f
0.18 0.09 1.1 1.2
0.08 0.02 1.7 1.9
Efficiency ()
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Results (hhhs pairs)
? background
signals ? ? ? ? ? f ? ? ? ?Dalitz
Central AuAu collision at 25 AGeV
S/B
Efficiency ratio
()

? 0.08 0.16 3.7 2.3
f 0.03 0.08 6 3.9
? 0.001 0.002 2.7 1.6
reconstructed after
bg pairs/event
cuts hh 1.410-2
3.810-3 hs 1.810-2
5.510-3
after cuts
after cuts
? background
signals ? ? ? ? ? f ? ? ? ?Dalitz
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Reconstructed ?0 hhhs pairs
without cuts after
cuts
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Reconstructed ?0 hhhs pairs
without cuts after
cuts
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Mass distribution for charm
PSTSvs.m2
ToF at 10 m
signal µ
bg µ
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Reconstructed background
after cuts
µ p ? ghost
particle ID 70 true hits
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Background suppression for J/?(?')
efficiency
central AuAu collisions at 25 AGeV
Nreco bg pairs event J/? (1.210-6) ?' (1.910-9)
without cuts 2 10-4 1.510-5 16 7 19 9
pt gt 1.2 GeV/c a gt 20 2 10-7 2.510-8 11 5 17 9
S/B 7
S/B 0.09
after mass cut
S/B 15
S/B 0.13
after mass cut
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Reconstructed charmonium
after mass cut
J/? ?'
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Invariant mass spectrum
with mass cut
central AuAu collisions at 25 AGeV
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Charmonium at 35 AGeV
PSTSvs.m2
ToF at 10 m
signal µ
bg µ
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Background suppression for J/?(?')
efficiency
central AuAu collisions at 35 AGeV
Nreco bg pairs event J/? (3.310-6) ?' (7.310-9)
without cuts 310-4 210-5 16 9 19 10
pt gt 1.2 GeV/c a gt 20 410-7 610-8 10 6 16 8
S/B 11
S/B 0.17
after mass cut
S/B 20
S/B 0.22
after mass cut
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Invariant mass spectrum
with mass cut
central AuAu collisions at 35 AGeV
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Conclusions

• Promising results for low-mass vector mesons
  using realistic segmentation of Muon System
• Good result for J/?
• ?' identification possible
• Good background suppression using time
  measurements

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Next steps

• Improvement of muon tracking
• Detector layout study (size, position resolution,
  type of detectors)
• Optimization of number of detector layers
• Decrease number of hits at ToF using pipe
  shielding and extended absorber

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Rvertexvs.Zvertex of tracks
hits/event
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pipe shielding extended absorber
W
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Rvertexvs.Zvertex of tracks
400 ToF hits/event
40 ToF hits/event
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Thank you for your attention!
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Backup
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Comparison of reco background
large MuCh
? 100µm smearing ? segmentation modified
tracking
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Modified tracking
compact MuCh
old tracking
hard tracks ? background ? signals soft
tracks background signals
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MC momentum
compact MuCh
? 4 STS 12 MuCh ? 4 STS 15 MuCh