CBM – MUCH Simulation
Activities in India - Status
Premomoy Ghosh
Variable Energy Cyclotron Centre
Calcutta, India
MuCh simulation activities at VECC prior
to last collaboration meeting
Detector
C-absorber
Fe-absorber
W-absorber
CWFe04 – (C75+W6)+C30+Fe40+(C80+W6)
e.g. Fe40 means 40cm thick Iron absorber
Total length = 257 cm
Gap between detectors = 4.5 cm
Detector Thickness – 1cm
27 September 2007
Premomoy Ghosh
10th. CBM Collaboration Meeting, Dresden
2
MuCh simulation status till last
collaboration meeting
Study of Different MuCh geometry layout at GSI, VECC,
PNPI………
Priority to unidirectional activity suggested for an early
result on MuCh feasibility study.
Optimum MuCh geometry configuration – “much_compact”
tagged with ToF, as studied at GSI for low mass vector
meson.
VECC to study J/Y & Y’ for geometries based on
“much_compact” version – to maintain the concept of
modular-geometry with minimum change in set-up for
study of entire di-muon mass-spectrum.
27 September 2007
Premomoy Ghosh
10th. CBM Collaboration Meeting, Dresden
3
What is done at VECC since last
meeting
Studied three geometries with different total absorber (Fe)
thickness
1) much_compact (125 cm)
2) much_medium (190 cm)
3) much_large (225 cm)
All these versions have same number (15) of detector
layers, gaps between detectors, between detector and
absorber, distance (102.5 cm) from the target.
27 September 2007
Premomoy Ghosh
10th. CBM Collaboration Meeting, Dresden
4
much_compact
125 cm
35 cm
30 cm
20 cm
20 cm
20 cm
Schematics of MuCh geometries
100 cm
30 cm
20 cm
20 cm
20 cm
F
e
much_medium
190 cm
100 cm
35 cm
30 cm
30 cm
30 cm
F
e
much_large
225 cm
F
e
27 September 2007
Premomoy Ghosh
10th. CBM Collaboration Meeting, Dresden
5
Framework & Tools
cbmroot FEB07 version
Au+Au 25 AGeV – central UrQMD events
Pluto generated muons
Sts geometry – Sts_2maps_6strips.geo
Sts track reconstruction - CA Tracking / Kalman Filter
MuCh track – Kalman Filter Extrapolation
Newly developed classes for realistic detector layout by
M. Ryzhinskiy and as used by A. Kiseleva are not included.
27 September 2007
Premomoy Ghosh
10th. CBM Collaboration Meeting, Dresden
6
Selection of Tracks
• Reconstructed tracks satisfying
– Number of STS-hits (NSts) >= 4 and
– True-hits/(true+wrong+fake hits) >0.7
– Number of MUCH-hits (NMuch) >9
• Terminology
– NMuch =15, i.e the track passing through all absorber layers,
is termed "Hard"
– NMuch =12, i.e is the track passing through four absorber
layers is termed "Soft"
In the following slides we present relevant results, in terms of
Hit-density, Signal reconstruction efficiency and Signal /
Background for J/Y, Y’ and
27 September 2007
w.
Premomoy Ghosh
10th. CBM Collaboration Meeting, Dresden
7
Comparison of hit-densities
27 September 2007
Premomoy Ghosh
10th. CBM Collaboration Meeting, Dresden
8
Signal/Background for J/Y & Y’ - large
much_large.geo
Reconstructed IM from
Hard Tracks
(NMuch=15) only
Super Event Analysis
with initial 10k UrQMD
central events
S/B from extrapolated
exponential fitting
For J/Y
S/BG = 10.2
e = 14 %
s = 22 MeV
For Y
S/BG = 3.33
e = 28 %
s = 26 MeV
27 September 2007
Premomoy Ghosh
10th. CBM Collaboration Meeting, Dresden
9
Signal/Background for J/Y & Y’ – large
contd.
Opening Angle cut of 12 degrees does
not help in improving S/BG.
27 September 2007
Premomoy Ghosh
10th. CBM Collaboration Meeting, Dresden
10
Signal/Background for w - large
Hard Tracks in much_large.geo
For w, S/BG = 0.56, e = 0.34 %
27 September 2007
, s = 7 MeV.
Premomoy Ghosh
10th. CBM Collaboration Meeting, Dresden
11
Signal/Background for J/Y & Y’ - medium
much_medium.geo
Reconstructed IM from
Hard Tracks
(NMuch=15) only
Super Event Analysis
with initial 10k UrQMD
central events
S/B from extrapolated
exponential fitting
For J/Y
S/BG = 5.4
e = 16 %
s = 22 MeV
For Y
S/BG = 1.82
e = 31 %
s = 26 MeV
27 September 2007
Premomoy Ghosh
10th. CBM Collaboration Meeting, Dresden
12
Signal/Background for w - medium
Hard Tracks in much_medium.geo
For w, S/BG = 0.34, e = 1 %
27 September 2007
, s = 7 MeV.
Premomoy Ghosh
10th. CBM Collaboration Meeting, Dresden
13
Summary & Plan for near future
J/Y and Y’ :
The numbers on S/BG, efficiency etc. presented here are good enough to
conclude that J/Y and Y’ reconstruction through di-m channel is feasible.
• Immediate plan is to implement realistic detector layout as studied at GSI.
• For proper estimation of S/BG - Super-Event Analysis with higher statistics
(simulated events) or some new method is needed.
• Parallel effort for other layout options needs to be continued.
Low mass vector mesons:
Momentum dependent muon identification with “detectors within absorber”
geometry layout only is not feasible, as yet.
• We plan to investigate the method involving information from ToF and by
optimizing (reducing) magnetic field.
We hope to progress in a faster rate with the possibility of active
participation of more Indian Collaborators.
27 September 2007
Premomoy Ghosh
10th. CBM Collaboration Meeting, Dresden
14
Latest Development in simualtion activities
Simulation Group formed in India-CBM Collaboration Meeting at Kolkata
on 30th-31st July 2007.
Framework and other codes installed at following Institutes/
Universities.
1.
University of Calcutta, Kolkata
2.
Indian Institute of Technology, Kharagpur
3.
Saha Institute of Nuclear Physics, Kolkata
4.
Benaras Hindu University, Varanasi
5.
Jammu University, Jammu
6.
Kashmir University, Srinagar
7.
Bhabha Atomic Research Centre
8.
Institute of Physics, Bhubaneswar
27 September 2007
Premomoy Ghosh
10th. CBM Collaboration Meeting, Dresden
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