Start Detector
for TOF@CBM@FAIR
- observation
- simulation
- realisation
ADAMAS Dec 2012
P.Koczoń / DetLab
GSI Helmholtzzentrum für
Schwerionenforschung GmbH
1
Piotr Koczoń,GSI
CBM@FAIR
2018?
ADAMAS Dec 2012
2
Piotr Koczoń,GSI
Compressed Baryonic Matter exp.
Reaction products
Target
TOF
MVD+STS
TARGET
ADAMAS Dec 2012
3
Piotr Koczoń,GSI
OBSERVATION:backward hemisphere
is full of reaction products
outside of acceptance
in acceptance
BEAM
TARGET
R=30mm
Beam pipe: 2.5°
Yoke: 25°
ADAMAS Dec 2012
4
Piotr Koczoń,GSI
Simulations to investigate
- time resolution of the first hit
- suitable detector geometry
- hit density
Details of the FAIR-Root simulations :
- event generators:
FAIR–IonGun Au on Au (for δ-electrons)
Urqmd (2 – 10 AGeV AuAu, NiNi MB and Central events)
- detector: two discs or a tube- like or sphere cutout (R=30 mm)
ALLWAYS with an opening allowing for 25 deg acceptance cone
- sensor material: Si (just because available as activ mat.)
- target Au, Ni, C
- projectile Au, Ni, p
ADAMAS Dec 2012
5
Piotr Koczoń,GSI
Simulations:
central events
 D = 0 fm
peripheral events (MB)
 events with impact parameter D
larger than 10 fm (selected from
the mbias urqmd-files)
y
D = impact_parameter
10 fm
x
ADAMAS Dec 2012
empty events
 99% HI produce only delta electrons
urqmd.auau.2gev.mbias.0021.ftn14
UQMD version:
10035 1000 10002 output_file…
transformation betas (NN,lab,pro) 0.0000000…
impact_parameter_real/min/max(fm): 10.98 0.00 15.82…
equation_of_state: 0 E_lab(GeV/u): 0.1271E+01 sqrt(s..
event#
1 random seed: 67008028 (fixed)
op 0 0 0 0 1 * 0 0 0 0 0 0 0 0 0 0
op 0 0 0 0 0 0 1 0 1 0 0 0 0 2 1
op 0 0 0 1 1 0 0 0 0 0 0 0 0 0 6 0
Piotr Koczoń,GSI
Ideal spherical detector
BEAM
28 mm
ADAMAS Dec 2012
7
Piotr Koczoń,GSI
2AGeV Au @ Au δ
+ Urqmd 2AGeV Au on 0.25mm Au (centr+MBias)
Φ[deg]
Detector can distinguish
δ’s
between central, min bias
MinBias Central
and empty events
(δE<10keV, holds also for a ring ,
or 2 discs shape)
Tot Eloss [keV]
time [ps]
ALL
25°
FIRST particle
RMS=4ps
curling δ’s
time [ps]
ADAMAS Dec 2012
Θ [deg]
HOTTEST area
8
opening circumference of 88 mm
Piotr Koczoń,GSI
Sphere cutout (crown) geometries
8fold 1ring
Θ=25-60 deg
60fold 1ring
Θ=25-35 deg
240fold 4rings
Θ=25-55 deg
ADAMAS Dec 2012
16fold 2rings
Θ=25-90 deg
120fold 2rings
Θ=25-45 deg
300fold 6rings
Θ=25-65 deg
9
Piotr Koczoń,GSI
Urqmd pC @ 30 GeV (central), 8-fold crown
Detector can deliver
start signal for TOF
with RMS ~ 20ps
and efficiency ~ 50 %
Timing: 18ps
Eff=50%
ADAMAS Dec 2012
10
Piotr Koczoń,GSI
Realisation (possible sensors):
price time res.
a) MCP discs of R=30mm
b) Si detectors R=30mm
c) Diamond det.
d) RPC barrel/discs
e) DIRC barrel
+
+
-?
--
70ps
+
<5ps
<40ps
50ps?
rate cap.
rad hard efficiency
++
+
++
20kHz cm2
?
+ HI?
+
++
+/-
>90% HI?
>90%
>90%?
>90 %
>90%?
(highly) segmented detectors!!!
ADAMAS Dec 2012
11
Piotr Koczoń,GSI
Conclusions:
presented results let us hope
that it is possible to construct a detector
- which can be used as START for
TOF@CBM (with time res. ~ 20 ps and 50%
efficiency for p+C)
- at the same time it would be a
reaction detector for AuAu, NiNi
(distinguishing central and min-bias react’s
from empty events)
- could be used as reaction tag (data flow
reduction est. by factor 2 – 3!)
ADAMAS Dec 2012
12
Piotr Koczoń,GSI
Outlook:
Having a segmented detector in the
vicinity of the target it should be possible
to measure the reaction plane as well
(subject for further smulations)
ADAMAS Dec 2012
13
Piotr Koczoń,GSI
ADAMAS Dec 2012
14
Piotr Koczoń,GSI
ADAMAS Dec 2012
15
Piotr Koczoń,GSI
Φ[deg]
Hit density
Θ [deg]
in the HOTTEST (red) area
(in the cell of 5x10deg ->2.6x5.2 mm = 13.6 mm2 size)
800 hits out of 1500 events ->
3.9 MHz/1 mm2 @ 1x109 s-1 Au on Au
ADAMAS Dec 2012
16
Piotr Koczoń,GSI
Z[mm]
Φ[deg]
For completeness: 2 discs of R=30mm
Θ [deg]
X [mm]
ADAMAS Dec 2012
17
Piotr Koczoń,GSI
start detector properties
- size: R~30 mm
- rate capability: several MHz / mm2 (worst case)
- first particle arrival time: RMS=10 ps
- having energy resolution of ~ 10 keV it can be
used for discrimination between empty events
(only delta electrons) and nuclear reactions
and
for centrality selection
ADAMAS Dec 2012
18
Piotr Koczoń,GSI