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CBM Collaboration meeting, February 11-13, 2004
GSI, Darmstadt
PID in the CBM by TOF
D.Kresan, I.Kadenko, O.Bezshyyko, V.Pluyko, V.Shevchenko
Taras Shevchenko National
University of Kyiv
Ukraine
Outgoal
• Hadron identification with TOF
• Impact of non-perfect PID on D0 detection
• Radiation damages in the STS
D. Kresan
University of Kyiv
2
PID by TOF
Efficiency of Kп‚± identification
as a function of momentum
TOF wall: to be placed at 10 or 15 m ?
parameters
particle multiplicities
time resolution – 80 or 60 ps
track length resolution – 4 mm
momentum relative uncert. – 6.4e-3
purity – 50 %
D. Kresan
10 GeV/u
пЃ°+
187
пЃ°214
K+
23
K4
University of Kyiv
25 GeV/u
пЃ°+
328
пЃ°368
K+
41
K13
3
PID results
15m wall – better resolution,
but higher decay
D. Kresan
10m + RPC improvement
gives roughly the same resolution,
with smaller losses in low momentum
University of Kyiv
4
PID results (2)
Identification probability
as a function of polar angle
KK-, decay
pt slope 151MeV
пЃіy = 0.85
D. Kresan
University of Kyiv
5
K
acceptance
STS
STS+TOF
laboratory momentum
distribution
STS+TOF+PID
10m, 80ps
transverse momentum
vs. rapidity
D. Kresan
University of Kyiv
6
0
D
significance
STS: standart setup
TOF: 10m
Acceptance,%
Inv. mass
Additional
S
S
S
B
STS
19.8
22.2
TOF
12.7
9.4
-
пЃіt=80ps
6.3
8.1
-
B
0.838 6.0e-4 48.5%
B
пЂјD пЂѕ
0
8.9
8.1e-4 51.0%
3.9e-6
7.8
5.4e-4 46.6%
2.5e-6
5.9
3пЃі detection limit
University of Kyiv
N ev
пЃі m MeV
3.8e-6
considering <D0>=10-3, пЃіm=18MeV, non-perfect PID
D. Kresan
SNR,
Nev=4.7e6
S/B=2
7
0
D
significance (2)
STS: standart setup
TOF: 15m
Acceptance,%
S
B
TOF
10.0
6.2
пЃіt=80ps
5.8
5.6
Inv. mass
S
Additional
B
0.838 9.2e-4
-
6.2e-4
0
B
52.3%
4.8e-6
6.6
49.7%
2.6e-6
6.3
3пЃі detection limit
University of Kyiv
пЂѕ
N ev
пЃі m MeV
S
considering <D0>=10-3, пЃіm=18MeV, non-perfect PID
D. Kresan
SNR, пЂј D
Nev=4.1e6
S/B=2.4
8
Background at 10 GeV/u
y0=1.53
пЃ°+ :
пЃ°+
пЃ°+
K-
K-
T=122 MeV
пЃіy=0.922
K- :
T=142 MeV
пЃіy=0.802
Transverse momentum and rapidity
distributions of K- and пЃ°+
748 background
pairs per event
D. Kresan
University of Kyiv
9
D0 significance at 10GeV/u
STS: standart setup
TOF: 10m
Acceptance,%
Inv. mass
Additional
SNR,
пЂјD пЂѕ
0
S
B
S
STS
17.2
25.9
TOF
10.9
9.3
-
пЃіt=80ps
5.3
8.4
-
B
S
0.838 3.5e-4 47.7%
D. Kresan
B
пЃі m MeV
2.4e-6
27.7
5.1e-4 50.6%
2.2e-6
26.9
3.7e-4 47.0%
1.8e-6
16.6
University of Kyiv
N ev
10
D0 significance at 10GeV/u (2)
STS: standart setup
TOF: 15m
Acceptance,%
S
B
TOF
8.4
5.6
пЃіt=80ps
4.8
5.3
Inv. mass
Additional
S
S
B
0.838 5.9e-4 51.0%
-
D. Kresan
4.6e-4 48.7%
University of Kyiv
SNR,
пЂјD пЂѕ
0
N ev
пЃі m MeV
B
2.8e-6
22.2
1.8e-6
17.6
11
Radiation damages in the STS
• Total Ionizing Dose
• Displacement damages
Calculation of equivalent dose rate and 1MeV neutron flux
for first two stations
Particle fluxes from central Au+Au collision @ 25AGeV
reaction rates 10MHz
D. Kresan
University of Kyiv
12
TID in the STS
Energy losses of charged
particles in first station
z=5cm, d=500пЃ­m
UrQMD + Geant4
D. Kresan
Quality factor vs.
specific energy losses
in water
University of Kyiv
13
Eq. dose rate distribution
z=5cm
worst
pixel :
0.68 Sv/s
z=10cm
worst
pixel :
0.45 Sv/s
D. Kresan
University of Kyiv
14
Displacement damage
Kinetic energy of particles,
produced in one event
UrQMD + Geant4
D. Kresan
Hardness parameter vs.
kinetic energy
University of Kyiv
15
Eq. neutron flux density
z=5cm
worst
pixel :
7e9 n/sпѓ—cm2
z=10cm
worst
pixel :
2.4e9 n/s пѓ—cm2
D. Kresan
University of Kyiv
16
Displacement effects
n doped
Taken from preparation
to In+In run
by NA60 collaboration *
p doped
U dep п‚µ N eff
N eff пЂЅ N
(0)
D
e
пЂ­ cпЃ†
пЂ­N
0
A
пЂ­ bпЃ†
* M.Keil, Effects of Radiation Damage in the NA60 Silicon Pixel Detectors
D. Kresan
University of Kyiv
17
Displacement effects (2)
For the silicon pixel telescope from NA60
considering estimated fluxes for the CBM experiment
At maximum rapidity type conversion after 4пѓ—109 events.
Depletion voltage п‚»250V after 7пѓ—1010 events.
But still depleted pixels at midrapidity
D. Kresan
University of Kyiv
18
Conclusion and next steps
• D0 significance was calculated with non-perfect PID
• Estimated radiation damages can be used in selection of
right candidate for STS
• TODO:
– Increasing of statistics in pointing angle distribution for
background at 10GeV/u
– Measurements of radiation damages effects on pixel detectors
(after making choice)
D. Kresan
University of Kyiv
19
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