1. 1 A.Andronic 1, H.Appelshäuser 1, V.Babkin 2, P.Braun-Munzinger 1, S.Chernenko 2, D.Emschernmann 3, C.Garabatos 1, V.Golovatyuk 2, J.Hehner 1, M.Hoppe 4, E.Jimenez 1, M.Kalisky 1, C.Lippmann 1, D.Moisa 5, F.Uhlig 1, M.Petris 5, M.Petrovici 5, A.Radu 1,5, V.Simion 5, R.Simon 1, H.-K.Soltveit 3, J.Stachel 3, H.Stelzer 1, A.Wilk 4, J.P.Wessels 4, Yu.Zanevsky 2, V.Zhezher 2 and V.Zryuev 2 High rate beam test of Gas Detectors 1 GSI Darmstadt; 2 JINR Dubna; 3 University of Heidelberg, 4 University of Münster, 5 NIPNE 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.

2. 2 Fig.1 Layout of the detector installation on the beam line Description of the experimental setup Detector type Active area (mm) Pitch (μm) Number of planes Detector “s task (destination) Scintillation counters50 x 40-2 Trigger, beam intensity monitor Microstrip detectors32 x 32502x, 2y Beam shape control Parameters of beam monitoring detectors

3. 3 Fig.2. Layout of MWPC prototypes. Left panel: chambers built at GSI and Bucharest, right panel: chamber built in Dubna. 3mm 2mm 1mm 3 4 1 2 65 78 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 ( cm 2 ) GSI-12307.5 x 8048 GSI-24307.5 x 8048 Bucharest2.5307.5 x 8048 Dubna2283.0 x 4.01.92 Mechanical parameters of MWPC’s used in the TRD test beam. 40 mm 50 mm 10 25 Active area of GEM

4. 4

5. 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

6. 6 Average pulse shape from FADC (50 bins x 30 nsec) for different readout chambers and different spill length

7. 7 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 = X exp – X coor 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. x x x x x x xx x x x x x Si-1(x,y)Si-2(x,y) GSI-1GSI-2PC-BucharestPC-DubnaGEM

8. 8 Steps of Data Analysis x x x x xx xx x x x x x Si-1(x,y)Si-2(x,y) GSI-1GSI-2PC-BucharestPC-DubnaGEM x x 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 = X exp – X coor 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.

9. 9 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

10. 10 GEM Ar/CO 2 GEM Xe/CO 2 Dubna Xe/CO 2 Dubna Ar/CO 2

11. 11 Xe/CO 2 GSI-1 GSI-2 Xe/CO 2 Ar/CO 2 GSI-2 Ar/CO 2

12. 12 Stability of the charge of signal from GEM and Dubna chamber vs beams intensity.

13. 13 Stability of the charge of signal from GSI chambers vs beam intensity

14. 14 Dubna, X-direction Xe/CO 2 Dubna, Y-direction Xe/CO 2 Pad numbers distribution in Dubna Chamber x y Sense wire 16 mm 12 mm n – number of pads taken for the measurement of center of gravity (position resolution)

15. 15 Dubna, X-direction Ar/CO 2 Dubna, Y-direction Xe/CO 2 Pad numbers distribution in Dubna Chamber (Ar/CO 2 ) Dubna, Y-direction Ar/CO 2 Dubna, Y-direction Ar/CO 2 Dubna, X-direction Ar/CO 2

16. 16 GSI-2 Ar/CO 2 7 mV GSI-2 Ar/CO 2 7 mV Pad number distribution and sp. resolution for GSI-2 chamber GSI-2 Ar/CO 2 10 mV GSI-2 Ar/CO 2 10 mV

17. 17 Space resolution vs beam Intencity for GSI-1 and GSI-2 Threshold =7mV Ar/CO 2

18. 18 Space resolution vs beam Intencity (Dubna chamber )

19. 19 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

20. 20 s1 s2 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 S 1 S m1 S m2 S 2 – to scaler to control number of beam particles passed through the Chambers under study S 1 S 2 - trigger For the next Run we need to 2 sec Beam intensity Beam extraction lenght

21. 21 10cm 2 8cm 2 6cm 2 4cm 2 2cm 2 1cm 2 10cm 2 1cm 2 2cm 2 4cm 2 6cm 2 8cm 2 TRD for CBM (3 stations) Au+Au, at 25 AGeV, min bias events, Hit rates10 7 10cm 2

22. 22 TRD for CBM Station №3

23. 23 GSI-1 Xe/CO 2 7 mV GSI-1 Xe/CO 2 7 mV GSI-1 Xe/CO 2 10 mV Cut, n>5 Pad number distribution and resolution for GSI-1 chamber (Xe/CO 2 ) GSI-1 Xe/CO 2 10 mV