Prezentacja programu PowerPoint

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Janusz Marzec, Krzysztof Zaremba
(speaker) Warsaw University of
Technology, Institute of Radioelectronics Departme
nt of Nuclear and Medical Electronics
Straw chamber readout
K.Zaremba, J.Marzec, CBM Meeting, 10.03.2005
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• The goal of the studies
• An analysis of the space resolution and high rate
  capability of the detector and the readout system
  for two readout scenarios
• anode readout
• cathode (pad) readout.

• Main effects taken into account
• angular effects
• high rate effects.

K.Zaremba, J.Marzec, CBM Meeting, 10.03.2005
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Angular effects in case of an anode readout
K.Zaremba, J.Marzec, CBM Meeting, 10.03.2005
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Angular effects in case of a pad readout
K.Zaremba, J.Marzec, CBM Meeting, 10.03.2005
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Simulations were performed under the following
assumptions         - thickness of the chamber
6 mm, gas mixture Xe CO2       - the
average distance between the clusters along the
particle track equal to 240 ?m,
- exponential distribution of the distance
between the clusters          - number of
electrons n in the cluster described by the
probability distribution wn0.6/n2         -
in case of electrons it was assumed that one
additional photon is detected with the energy
from the uniform distribution in the range of
5-20 keV, originated in the random point of the
particle track (uniform distribution).
K.Zaremba, J.Marzec, CBM Meeting, 10.03.2005
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Angular effects in case of a pad readout
Centre of gravity distribution
s 760 µm
K.Zaremba, J.Marzec, CBM Meeting, 10.03.2005
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Space resolution versus the incident particle
angle for electrons and pions
K.Zaremba, J.Marzec, CBM Meeting, 10.03.2005
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Resolution limits over the chamber area
6 mm chamber
Conclusion flat detector is unacceptable
K.Zaremba, J.Marzec, CBM Meeting, 10.03.2005
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6 mm Xe CO2 chamber
gaussian shaping 4 x int
tp 12 ns
Anode (time) readout
quasi-current mode (tP lt tC)
0
100
200
300
400 ns
tp 120 ns
Cathode-pad (amplitude) readout
charge mode (tP gt tC)
0
100
200
300
400 ns
K.Zaremba, J.Marzec, CBM Meeting, 10.03.2005
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Collision area
should be
x (SR-SL)/(SLSSR)
SA
SB
SC
it is
SARSBL
SBRSCL
SA
SB
SC
x(SBRSCL-SAR-SBL)/(SARSBLSBSBRSCL)
Collision area readout channel area
Lost events collision area 2 x redout channel
area
Large errors collision area 5 x redout channel
area
K.Zaremba, J.Marzec, CBM Meeting, 10.03.2005
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Pulse pile-up error distribution
5 mm thick chamber
pads 5 x 40 mm
particle flux 1.2105
pulse shaping tp100ns

• MC simulation assumptions
• Signal shaping
• gaussian 4 x int.
• Perfect tail cancelation
• Perfect base line restoration

Large errors due to the pile-ups from neighboring
pads
K.Zaremba, J.Marzec, CBM Meeting, 10.03.2005
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Cathode pads (amplitude) readout versus anode
(time)readout for 1.2x105 1/cm2s particle flux
Pads 2 cm2 (5x40 mm) tW 200 ns Straws 8 cm2 tW 100 ns
Lost events 10 10
Normal error events 55 89
Large error events 35 1
K.Zaremba, J.Marzec, CBM Meeting, 10.03.2005
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MC simulation results
5 mm thick chamber
For 1 cm2 pads and error lower than 400 µm for
95 of events particle flux should be lower than
30000 1/cm2s
K.Zaremba, J.Marzec, CBM Meeting, 10.03.2005
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Low particle flux case

• pad width limited to (1?2) x chamber thickness
  (5?10 mm)
• pads in the form of the long strips

1. Strips in a free space (low capacitance to
the ground) Strong cross-talk between strips
(signal diffusion during the transmittion)
2. Strip transmittion lines (high capacitance to
the ground) Electronic noise problems (high
amplifier input capacitance) Low input
impedance of the amplifier is necessary
K.Zaremba, J.Marzec, CBM Meeting, 10.03.2005
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ASD8-B versus IRIMIO parameters
ASD-8B IRIMIO
Technology bipolar BiCMOS
Input range 100 fC 100 fC
Input impedance 120 ? 10 ?
Input noise 1000 e 1000 e
Shaping Gauss 3 x int tP 12 ns Gauss 4 x int tP 7 ns
Tail cancellation For t0 2 ns For t0 2 ns
Base line restorer no 0.017 fC/ns () 0.17 fC/ns (-)
Threshold 0-150 fC nonlinear 0-20 fC linear
Power supply 3 v, -3V 3V, -2V
Power consumption 41 mW per ch. 35 mW per ch.
K.Zaremba, J.Marzec, CBM Meeting, 10.03.2005