Expected Performances of the scintillator counters Time Of Flight system of the AMS-02 experiment

Transcription

1 Expected Performances of the scintillator counters Time Of Flight system of the AMS-02 experiment Cristina Sbarra for the AMS-TOF Bologna group INFN-Bologna (Italy) Cristina Sbarra INFN-Bologna p.1/13

2 Contents The TOF-02 design and mechanics Cristina Sbarra INFN-Bologna p.2/13

3 Contents The TOF-02 design and mechanics The fine mesh PMs and their displacement on the TOF-02 Cristina Sbarra INFN-Bologna p.2/13

4 Contents The TOF-02 design and mechanics The fine mesh PMs and their displacement on the TOF-02 The TOF-02 counters and the space qualification tests Cristina Sbarra INFN-Bologna p.2/13

5 Contents The TOF-02 design and mechanics The fine mesh PMs and their displacement on the TOF-02 The TOF-02 counters and the space qualification tests Trigger acceptance Cristina Sbarra INFN-Bologna p.2/13

6 Contents The TOF-02 design and mechanics The fine mesh PMs and their displacement on the TOF-02 The TOF-02 counters and the space qualification tests Trigger acceptance Beam test results Cristina Sbarra INFN-Bologna p.2/13

7 The requirements for the TOF the fast trigger to the whole experiment; measurement of the CR time of flight with a resolution to distinguish upward from downward going particles at a level of 10 9 level, and electrons from antiprotons at low momentum; the measurement of the absolute charge in addition to the measurement done by the tracker and the rich. Cristina Sbarra INFN-Bologna p.3/13

8 The TOF-02 design and mechanics geometrical acceptance fixed => 0.4 m 2 sr Cristina Sbarra INFN-Bologna p.4/13

9 The TOF-02 design and mechanics geometrical acceptance fixed => 0.4 m 2 sr 4 planes, each covering a circular area of 1.2 m 2 Cristina Sbarra INFN-Bologna p.4/13

10 The TOF-02 design and mechanics geometrical acceptance fixed => 0.4 m 2 sr 4 planes, each covering a circular area of 1.2 m 2 12 cm wide scintillators pads for plane (0.5 cm overlapped) Cristina Sbarra INFN-Bologna p.4/13

11 The TOF-02 design and mechanics geometrical acceptance fixed => 0.4 m 2 sr 4 planes, each covering a circular area of 1.2 m 2 12 cm wide scintillators pads for plane (0.5 cm overlapped) to minimize the angle between the PM axis and B => curved and twisted light guides Cristina Sbarra INFN-Bologna p.4/13

12 The TOF-02 design and mechanics PMs Conical light guides Curved light guides Scintillator Clear plastic Cristina Sbarra INFN-Bologna p.5/13

13 The TOF-02 design and mechanics upper (left) and lower (right) TOF planes Cristina Sbarra INFN-Bologna p.5/13

14 The TOF-02 design and mechanics An exploded view of the complete TOF structure Cristina Sbarra INFN-Bologna p.5/13

15 The Fine Mesh PMs Hamamatsu R5946 bialkali photocathode 16 bialkali mesh dynodes max spectral response at 450nm (QE 20%) Cristina Sbarra INFN-Bologna p.6/13

16 The Fine Mesh PMs magnetic field effect on PM response Cristina Sbarra INFN-Bologna p.6/13

17 The Fine Mesh PMs magnetic field effect on time response Cristina Sbarra INFN-Bologna p.6/13

18 The Fine Mesh PMs: work done 195 fine mesh PMs calibrated in 2003 Cristina Sbarra INFN-Bologna p.7/13

19 The Fine Mesh PMs: work done 195 fine mesh PMs calibrated in 2003 PMs classified with respect to their working HV ( HV to have G = ) Cristina Sbarra INFN-Bologna p.7/13

20 The Fine Mesh PMs: work done 195 fine mesh PMs calibrated in 2003 PMs classified with respect to their working HV ( HV to have G = ) a genetic alghorithm has been used to displace the calibrated PMs in the TOF-02 structure, using the working HV calculated and other measurements previously made in the magnetic field (<- ICRC 2001). Cristina Sbarra INFN-Bologna p.7/13

21 The Fine Mesh PMs: work done 195 fine mesh PMs calibrated in 2003 PMs classified with respect to their working HV ( HV to have G = ) a genetic alghorithm has been used to displace the calibrated PMs in the TOF-02 structure, using the working HV calculated and other measurements previously made in the magnetic field (<- ICRC 2001). calibration results and PMs displacement are on line ( Cristina Sbarra INFN-Bologna p.7/13

22 Counters and space qualification tests The TOF-02 counters are being characterized in the INFN laboratories of Bologna with a Cosmic Rays telescope in order to find: Cristina Sbarra INFN-Bologna p.8/13

23 Counters and space qualification tests The TOF-02 counters are being characterized in the INFN laboratories of Bologna with a Cosmic Rays telescope in order to find: Attenuation Lenght V light in the counter Cristina Sbarra INFN-Bologna p.8/13

24 Counters and space qualification tests The TOF-02 counters are being characterized in the INFN laboratories of Bologna with a Cosmic Rays telescope in order to find: Attenuation Lenght V light in the counter Photostatistics (N. of photons in the center ) Cristina Sbarra INFN-Bologna p.8/13

25 Counters and space qualification tests The TOF-02 counters are being characterized in the INFN laboratories of Bologna with a Cosmic Rays telescope in order to find: Attenuation Lenght V light in the counter Photostatistics (N. of photons in the center ) Intrinsic time resolution (count. sides time difference) Cristina Sbarra INFN-Bologna p.8/13

26 Counters and space qualification tests The TOF-02 counters are being characterized in the INFN laboratories of Bologna with a Cosmic Rays telescope in order to find: Attenuation Lenght V light in the counter Photostatistics (N. of photons in the center ) Intrinsic time resolution (count. sides time difference) Time of flight resolution (count. - ref. time difference) Cristina Sbarra INFN-Bologna p.8/13

27 Counters and space qualification tests The TOF-02 must be able to operate in space for three years and must substain the acceleration of the launch, thus it must undergo several thermal-vacuum and mechanical tests: Cristina Sbarra INFN-Bologna p.9/13

28 Counters and space qualification tests The TOF-02 must be able to operate in space for three years and must substain the acceleration of the launch, thus it must undergo several thermal-vacuum and mechanical tests: A group of 10 PMs was tested in the simulator for dark curr and pulse height meas. (=> see the poster C) A complete counter was also tested Cristina Sbarra INFN-Bologna p.9/13

29 Counters and space qualification tests The TOF-02 must be able to operate in space for three years and must substain the acceleration of the launch, thus it must undergo several thermal-vacuum and mechanical tests: A group of 10 PMs was tested in the simulator for dark curr and pulse height meas. (=> see the poster C) A complete counter was also tested Results are encouraging Cristina Sbarra INFN-Bologna p.9/13

30 Counters and space qualification tests Counter characterization before and after test Cristina Sbarra INFN-Bologna p.10/13

31 Counters and space qualification tests Counter characterization before and after test => Results are the same bef.: L n = 177 cm, L p = 156 cm after: L n = 176 cm, L p = 154 cm error: ± 1 2% Cristina Sbarra INFN-Bologna p.10/13

32 Counters and space qualification tests Counter characterization before and after test => Results are the same bef.: L n = 177 cm, L p = 156 cm after: L n = 176 cm, L p = 154 cm error: ± 1 2% =>counter beared the test AMS-BO internal notes - Cristina Sbarra INFN-Bologna p.10/13

33 Trigger efficiency The FT is generated when 3/4 TOF planes signals above a Threshold Cristina Sbarra INFN-Bologna p.11/13

34 Trigger efficiency The FT is generated when 3/4 TOF planes signals above a Threshold The TOF flags CRs with Z > 1 Cristina Sbarra INFN-Bologna p.11/13

35 Trigger efficiency The FT is generated when 3/4 TOF planes signals above a Threshold The TOF flags CRs with Z > 1 A threshold of 3.5 mip can suppress 99% of the protons without affecting eavier ions efficiency efficiency p, cut on side p, cut on sum He, cut on side He, cut on sum Li, cut on side Li, cut on sum cut (m.i.p.) Cristina Sbarra INFN-Bologna p.11/13

36 Beam test results Four TOF scintillators were used during ion test beam at CERN 2003 Cristina Sbarra INFN-Bologna p.12/13

37 Beam test results Four TOF scintillators were used during ion test beam at CERN 2003 the two worst counters for guides: C2 and C3 Cristina Sbarra INFN-Bologna p.12/13

38 Beam test results Four TOF scintillators were used during ion test beam at CERN He Entries Ion charge is well measured by all counters H 2p Li Be B C N O F Ne Na Mg Al C2 left anode, sqrt(adc) Cristina Sbarra INFN-Bologna p.12/13

39 Beam test results Four TOF scintillators were used during ion test beam at CERN 2003 σ Z P E E 02 P E E charge resolution for anodes and dynodes is computed σ Z Z C2AR P1 P E E E E Z C2DR 12 Cristina Sbarra INFN-Bologna p.12/13

40 Beam test results Four TOF scintillators were used during ion test beam at CERN 2003 Z TOF 30 ENTRIES the TOF data are compared with RICH measurements Z RICH Cristina Sbarra INFN-Bologna p.12/13

41 Conclusions With the TOF design and the phototubes characterization the fine mesh PMs were displaced in the structure Cristina Sbarra INFN-Bologna p.13/13

42 Conclusions With the TOF design and the phototubes characterization the fine mesh PMs were displaced in the structure The TOF system can operate from 40 to +50 Celsius without major problems Cristina Sbarra INFN-Bologna p.13/13

43 Conclusions With the TOF design and the phototubes characterization the fine mesh PMs were displaced in the structure The TOF system can operate from 40 to +50 Celsius without major problems The trigger acceptance allows to suppress 99% of the proton flux at level-1 trigger Cristina Sbarra INFN-Bologna p.13/13

44 Conclusions With the TOF design and the phototubes characterization the fine mesh PMs were displaced in the structure The TOF system can operate from 40 to +50 Celsius without major problems The trigger acceptance allows to suppress 99% of the proton flux at level-1 trigger From the last beam test results it can be inferred a counter intr. time res. of 150 ps (TOF web page ) Cristina Sbarra INFN-Bologna p.13/13