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SIS-100 simulation. Partha Pratim Bhaduri Subhasis Chattopadhyay VECC, Kolkata. p-A simulation for J/ y at SIS-100 Much geometry optimization for SIS-100. p-A simulation. Motivation. - PowerPoint PPT Presentation
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SIS-100 simulationSIS-100 simulation
Partha Pratim BhaduriSubhasis Chattopadhyay
VECC, Kolkata
p-A simulation for J/ at SIS-100
Much geometry optimization for SIS-100
p-A simulation
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Motivation
• The aim of the relativistic heavy-ion collisions is to study the onset of de-confinement and the properties of the de-confined media in the laboratory. Hence it is necessary to define unambiguous and experimentally viable probes for de-confinement.
• In this respect proton-nucleus (p+A) collisions must be a fundamental component of any heavy-ion physics program
• Defines the reference baseline relative to which we recognize HI specific phenomena
• p+A collisions provide a measure of the nuclear effects – helps in disentangling the “QGP” effect from the “non-QGP” effects. Here there is no formation time for the “secondary” medium , hence such collisions provide as essential tool to correctly account for the effect of the nuclear medium initially present.
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System
• The specifications of the system chosen are:
Target : Au, Cu, S, O, C Projectile : p (1, 1) Beam energy : 30 GeV Event generator used : HSD – 2.5 Events : 5,000 (ISUBS = 50, NUM = 100)
Results with HSD
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J/ pseudo-rapidity distribution
pCpOpSpCupAu
pCpOpSpCupAu
CMS Frame Laboratory Frame
J/ transverse momentum spectra
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pCpOpSpCupAu
HSD vs. Pluto (muon pseudo-rapidity distribution)
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HSD Pluto
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CMS Frame Laboratory Frame
Laboratory Frame
Muons decayed from J/ Isotropic decay in J/ rest frame
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CbmRoot Version: Trunk version
Number of events : 4000
Much geometry : Standard Geometry
• 2 layers in 5 stations
• Distance between layers 10 cm.
• Gap between absorbers 20 cm
• 3 layers at the last trigger station
• Total 13 layers
• Total length of Much 350 cm
Signal : J/ decayed muons from HSD for p+Au system for 30 GeV p beam
Background : central UrQMD events for p+ Au at 30 GeV/n
Much Hit producer w/o cluster & avalanche
L1(STS) & Lit (Much) tracking with branching
Simulation
Absorber thickness (cm):20 20 20 30 35 100
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Analysis
• Use the reconstructed data after the full tracking through the detector set-up.
• Reconstructed global tracks have to satisfy :
1. Fraction of true hits (truehits/(true hits+ wrong hits+fake hits) >= 0.7
2. No. of STS Hits associated with the global track >=4
3. No. of Much Hits associated with the global track >=10
4. Chi2 primary <=2
Detector Acceptance
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Raw HSDLayer # 1Layer # 3Layer # 5Layer # 7Layer # 9Layer # 11
Invariant mass spectra
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Embedded Reconstruction efficiency : 23.8 %
Pure HSDReconstruction efficiency : 25 %
Negligible background effect
Geometry optimization
• Our aim is to optimize the geometry of the muon set-up for SIS-100.
• Optimization should be done with low mass vector mesons (lmvms) rather than J/ψ and at the lowest available energy.
• J/ψ measurements due to low background after more than 2 m of Fe are not so sensitive to the muon setup as the measurements of muons from LMVM.
• Issue is to reconstruct the soft muons ( eg: ω→μμ )
• We have chosen central Au+Au events at 8 AGeV together with ω→μμ.
• Use the same set-up in simulation for J/ψ & LMVM. For LMVM use information from stations just before the last thick absorber.
• Run full simulation & obtain signal reconstruction efficiency & S/B ratio.
• Statistics : 10k central events
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– We have to decide upon :– Total number of stations(layers)– Total absorber thickness, total no. of absorbers & the
absorber material– Number of stations (2/3) in between two absorbers– Distance between stations & absorber to station distance
– Present constraints in simulation :– Absorber material (Fe, Pb, W )– Layer to layer distance >= 10 cm.– Absorber to layer distance >= 5cm.
Absorber thickness (cm):20 20 20 30 35 100
Reconstruction efficiency : 0.5 % Estimated Signal : 645.234 Estimated Bkg. : 573.028 S/B : 1.126
Cuts :1.No. of Much hits>=92.70 % true hit3.No. of STS Hits >=4
Number of stations : 13(2+2+2+2+2+3)Absorber to station distance : 5 cm.Layer to layer distance : 10 cm.
Super event (SE) analysis for bkg.Gaussian fit to signalPolynomial fit to bkg.
Cuts :1.No. of Much hits>=92.70 % true hit3.No. of STS Hits >=4
Option II : Reduced geometry
Absorber thickness (cm):20 20 30 35 100
Number of stations : 11(2+2+2+2+3)Absorber to station distance : 5 cm.Layer to layer distance : 15 cm.
GEM Modules : 25.6 cm. * 25.6 cm.# of modules : 1928
Super event (SE) analysis for bkg.Gaussian fit to signalPolynomial fit to bkg.
Reconstruction efficiency : 1.6 % Estimated Signal : 3997.52 Estimated Bkg. : 30052.1 S/B : 0.133
Cuts :1.No. of Muchhits>=72.70 % true hit3.No. of STS Hits >=4
Option III : Reduced Geometry
Number of stations : 9 (3+3+3)Absorber to station distance : 10 cm.Layer to layer distance : 10 cm.
Absorber thickness (cm):30 70 125
Super event (SE) analysis for bkg.Gaussian fit to signalPolynomial fit to bkg.
Reconstruction efficiency : 1.4 % Estimated Signal : 2874.44 Estimated Bkg. : 9936 S/B : 0.2866
Cuts :1.No. of Muchhits>=72.70 % true hit3.No. of STS Hits >=4
GEM Module : 25.6cm.*25.6 cm.
# of Modules : 1512
Comparison of different geometries
configuration # of stations
Total absorber thickness (cm.)
Much Hit cut
Reco. eff
S/B
Standard 13 125 >=9 0.5 % 1.126
Reduced – I 11 105 >=7 1.6 % 0.133
Reduced - II 9 100 >=5 1.4 % 0.287
To do list …..
• Continue the study with 9 station configuration but with same total absorber thickness (125 cm.)
• Test the configuration for charmonia• Study of gaps ( station to station & station to
absorber)