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A.Andronic1, H.Appelshäuser1, V.Babkin2, P.Braun-Munzinger1, S.Chernenko2, D.Emschernmann3, C.Garabatos1, V.Golovatyuk2, J.Hehner1, M.Hoppe4, E.Jimenez1, M.Kalisky1, C.Lippmann1, D.Moisa5, F.Uhlig1, M.Petris5, M.Petrovici5, A.Radu1,5, V.Simion5, R.Simon1, H.-K.Soltveit3, J.Stachel3, H.Stelzer1, A.Wilk4, J.P.Wessels4, Yu.Zanevsky2, V.Zhezher2 and V.Zryuev2
High rate beam test of Gas Detectors
1GSI Darmstadt; 2JINR Dubna; 3University of Heidelberg, 4University of Münster, 5NIPNE Bucharest
Results of experimental data analysis taken on the SIS GSI beam are presented. As a prototype of TRD detector, four proportional chambers of different configurations and one GEM detector were used. The main goal of experiment was studying the variation of detectors response under irradiation by high intensity beams.
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Fig.1 Layout of the detector installation on the beam line
Description of the experimental setup
Detector typeActive area
(mm)Pitch
(μm)Number of planes
Detector “s task (destination)
Scintillation counters 50 x 40 - 2Trigger, beam
intensity monitor
Microstrip detectors 32 x 32 50 2x, 2yBeam shape
control
Parameters of beam monitoring detectors
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Fig.2. Layout of MWPC prototypes. Left panel: chambers built at GSI and Bucharest, right panel: chamber built in Dubna.
3mm
2mm
1mm
1mm
3 4 1 2
6 5 7 8
Fig. 3. The scheme of the GEM detector used as a prototype for CBM TRD
Holes are bi-conical with external diameter 70 μm, internal – 50 μm , pitch – 140 μm
wire pitch(mm)
anode-cathode
gap(mm)
drift region(mm)
pad size(mm)
active area( cm2 )
GSI-1 2 3 0 7.5 x 80 48
GSI-2 4 3 0 7.5 x 80 48
Bucharest 2.5 3 0 7.5 x 80 48
Dubna 2 2 8 3.0 x 4.0 1.92
Mechanical parameters of MWPC’s used in the TRD test beam.
40 mm
50
mm
10
25
Active area of GEM
4
5
Fig.5. Beam intensity distribution during the spill.The figures represent the case when extraction
time was 0.15 and 2.0 sec.
0.15 sec
The information from the upstream scintillation counter which covers the beam also was used for a total beam intensity estimation. Number of counts in this counter happened in time from the previous trigger was recorded.
Having in addition information from the clock about time between triggers we are able to recover the time structure of the beam passed through our detectors.
2.0 sec
Beam Intensity estimation
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Average pulse shape from FADC (50 bins x 30 nsec) for different readout chambers and different spill length
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Steps of Data Analysis
1. “Track” reconstruction with help of two Si (x and y strips with 50 μm pitch) stations.
2. Calculation expected track coordinate in each detector
3. Search for signals beyond the threshold around expected position
4. Calculation residuals R = Xexp – Xcoor
5. Calculation the total charge (sum up the signals from adjacent strips (pads))
6. Calculation of center of gravity using signals from adjacent strips, (σ ~ 0.4 - 0.6 mm)
7. Check the track validity using addition coordinate information from proportional chambers
Selection of tracks which have small residuals on selecteted chambers.
xx x
xx x xx
xx
xxx
Si-1(x,y) Si-2(x,y)
GSI-1 GSI-2 PC-Bucharest PC-Dubna GEM
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Steps of Data Analysis
xx x
xx x xx
xx
xxx
Si-1(x,y) Si-2(x,y)
GSI-1 GSI-2 PC-Bucharest PC-Dubna GEM
xx
1. “Track” reconstruction with help of two Si (x and y strips with 50 μm pitch) stations.
2. Calculation expected track coordinate in each detector
3. Search for signals beyond the threshold around expected position
4. Calculation residuals R = Xexp – Xcoor
5. Calculation the total charge (sum up the signals from adjacent strips (pads))
6. Calculation of center of gravity using signals from adjacent strips, (σ ~ 0.4 - 0.6 mm)
7. Check the track validity using addition coordinate information from proportional chambers
Selection of tracks which have small residuals on selecteted chambers.
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30 mm
7 mm
Strip position of GSI-1 chamber defined with Si “tracker”
Pads position of Dubna’s MWPC defined with Si “tracker”
3 mm
4 mm
Pads position of GEM defined with Si “tracker”
10mm
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GEM
Ar/CO2
GEM
Xe/CO2
Dubna
Xe/CO2
Dubna
Ar/CO2
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Xe/CO2
GSI-1 GSI-1
GSI-2
Xe/CO2
Ar/CO2
GSI-2
Ar/CO2
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Stability of the charge of signal from GEM and Dubna chamber vs beams intensity.
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Stability of the charge of signal from GSI chambers vs beam intensity
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Dubna, X-direction
Xe/CO2
Dubna, Y-direction
Xe/CO2
Pad numbers distributionin Dubna Chamber
x
y
Sense wire
16 mm
12
mm
n – number of pads taken for the measurement of center of gravity (position resolution)
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Dubna, X-direction
Ar/CO2
Dubna, Y-direction
Xe/CO2
Pad numbers distribution in Dubna Chamber (Ar/CO2)
Dubna, Y-direction
Ar/CO2
Dubna, Y-direction
Ar/CO2
Dubna, X-direction
Ar/CO2
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GSI-2
Ar/CO2
7 mV
GSI-2
Ar/CO2
7 mV
Pad number distribution and sp. resolution for GSI-2 chamber
GSI-2
Ar/CO2
10 mV
GSI-2
Ar/CO2
10 mV
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Space resolution vs beam Intencity for GSI-1 and GSI-2 Threshold =7mV
Ar/CO2
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Space resolution vs beam Intencity
(Dubna chamber)
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Conclusions
1. We did not observe a gas gain degradation up to intensity of 100 kHz/cm² in MWPCs with Ar/CO-2 and Xe/CO-2 mixtures.
2. We did not observe a spatial resolution worsening vs beam intensity for Dubna chamber (with a small pad size). A contribution of multiple scattering is significant in obtained spatial resolution for MWPCs (especially for Dubna chamber). 3. Pad size of MWPC should be optimized for the next beam test
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s1 s2
X-Y Coordinates X-Y Coordinates
Chambers under study
• Minimize a multiple scattering (everything besides chambers has to be taken out of the beam area)• Use fast 2D coordinate detectors for beam profile definition (GEM) (for signal degradation in high intensity beams studies a coordinate resolution of coordinate detectors (1-2) mm is enough )• Provide beam intensity variation with a long spill length (2 sec)• Try to decrease size of the beam (1-2 cm² ).• Increase number of DAQ channels.
Ch1 Ch2
S1 Sm1 Sm2 S2 – to scaler to control number of beam particles passed through the Chambers under study
S1S2 - trigger
For the next Run we need to
2 sec
Beam intensity
Beam extraction lenght
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10cm2 8cm2 6cm2
4cm2 2cm2 1cm2
10cm2
1cm2
2cm2
4cm2
6cm2
8cm2
TRD for CBM(3 stations)
Au+Au, at 25 AGeV, min bias events, Hit rates107
10cm2
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TRD for CBM Station №3
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GSI-1
Xe/CO2
7 mV
GSI-1
Xe/CO2
7 mV
GSI-1
Xe/CO2
10 mV
Cut, n>5
Pad number distribution and resolution for GSI-1 chamber (Xe/CO2 )
GSI-1
Xe/CO2
10 mV