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Jerzy Pietraszko a ,W. Koenig a , S. Spataro b for the HADES Collaboration

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Jerzy Pietraszko a ,W. Koenig a , S. Spataro b for the HADES Collaboration

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  1. Beam detectors in Au+Au run and future developments- Results of Aug 2012 Au+Au test – radiation damage- scCVD diamond detector with strip metalization in Apr 2012- Detector calibration for the DST production for Apr2012 experiment- Future developments: - pion beam - CBM/HADES at SIS100 and CBM @ SIS300 Jerzy Pietraszkoa ,W. Koeniga, S. Spatarob for the HADES Collaboration a GSI Helmholtz Centre for Heavy Ion Research GmbH Planckstrasse 1, D-64291 Darmstadt, GERMANY b Universita' di Torino - Dipartimento di Fisica Generale, Torino, ITALY HADES Collaboration Meeting XXV, GSI, Darmstadt, 19-22 November 2012.

  2. Radiation hardness study with Au beam (Aug11)reminder Dismounted Start detector: Beam spot: 0.8x1.6mm2 HADES Collaboration Meeting XXV, GSI, Darmstadt, 19-22 November 2012.

  3. Radiation hardness study with Au beam (Au 2011) reminder + 30 % DAQ off + 30 % beam times in 2010 • 3.04 x 1011 Au ions / mm2 • total absorbed dose: 7.9 Grad 1.9 x 10 11 Au ions ADC spectra (at 60 V) Pu239 - Am241 - Cm244 (vacuum) 5.157 MeV - 5.486 MeV - 5.804 MeV Total dose during 5 days measured in the Start detector inner segments outer segments HADES Collaboration Meeting XXV, GSI, Darmstadt, 19-22 November 2012.

  4. Radiation hardness study with Au beam (Au 2011) signal characteristics • Diamonds behave differently being irradiated by Au beam and by Alpha particles Simple model:capacitor 0.4mm x 0.4mm at 100V  charge deposited: 7.4 pC Au ion  charge deposited: 1.8 pC  effective field reduced HV [V] HADES Collaboration Meeting XXV, GSI, Darmstadt, 19-22 November 2012.

  5. Radiation hardness study with Au beam - amplitude reduction Threshold characteristics (Aug11): cut amplitudes lower than 35mV • After 3.04 x 1011 Au ions /mm2 5% of signals below 35 mV (7.9 Grad) • Amplitude reduction by a factor of 2.7 Analog signals, Au beam, HV: 100V Amplitude; 94 mV HADES Collaboration Meeting XXV, GSI, Darmstadt, 19-22 November 2012.

  6. The start detector for Apr12 As produced: As planned: - diamond sensor, 16 stripes on each side • holder which allows the detector to be moved • beam spot: ellipse - 16 stripes on each side • strip width: 200µm • gap: 90 µm • det. thickness about 60 µm  large field inhomogeneity Main improvement:  Double-sided multi-strip diamond based sensor for HI (16 channels on each side) HADES Collaboration Meeting XXV, GSI, Darmstadt, 19-22 November 2012.

  7. The start detector for Apr12readout electronics  helped a lot to compensate for the reduction of the signal due to large field inhomogeneity caused by too wide gaps between strips !!!! Analog signals, strip detector (Start X) one channel, Au beam, HV: 100V, Amplifier: x10, huge signal amplitude variations: 0 – 350 mV (threshold set to 13mV ) Analog signals of the “old” diamond (used in aug11) Au beam, HV: 100V constant signal amplitude: 100 mV Main improvement:  fast analog amplifier (x 10) installed to compensate for the reduction of the signal HADES Collaboration Meeting XXV, GSI, Darmstadt, 19-22 November 2012.

  8. New start detector for Apr12 Time res of the StartX, Apr12, beam data, day 097 (Start X vs Veto ch0, not divided by 1.4) 4% 4% 0.6% Intrinsic time resolution: Side X better than 60 ps, Side Y better than 70 ps HADES Collaboration Meeting XXV, GSI, Darmstadt, 19-22 November 2012.

  9. The start detector for Apr12 Detector efficiency, Apr12, beam data, day 097 Start detector Veto detector 8mm HADES Collaboration Meeting XXV, GSI, Darmstadt, 19-22 November 2012.

  10. Calibration of the start detector for Apr12(Stefano Spataro) - Calibration is based on reconstructed pions in the META - Each start detector channel is calibrated separately - Calibration parameters prepared for each run • example for Aug11 the same procedure used for Apr12 data Before calibration Strip 1 Strip 2 Strip 3 Strip 4 After calibration Strip 1 Strip 2 Strip 3 Strip 4 HADES Collaboration Meeting XXV, GSI, Darmstadt, 19-22 November 2012.

  11. Start detector analysis improvement for Apr12 – high rate experiments T0 determination • Increased probability at higher beam intensity • Significant effect coming from micro-spill structure  wrongly assigned T0 in Time-of-Flight determination procedure (below 10 %) Start X Start Y Veto SIS 18/100 crew is aware of this problem. Solution is needed for FAIR. Tof and RPC hits HADES Collaboration Meeting XXV, GSI, Darmstadt, 19-22 November 2012.

  12. Start detector analysis – T0 determination • Use Start X and Start Y (both sides of the Start detector) • Use three fastest particles in RPC/TOF from hit level (before tracking !!!) to define the reaction (7 ns ToF of fastest particles)  wrongly assigned T0 in Time-of-Flight determination procedure ToF of the three fastest particles in TOF and RPC, ToF normalized to the same path length  2-3 ns precision Implemented, ready to be used in DST gen1. cases: 0. StartX 1. StartY 2. Start X and Y (mean) HStart2Hit::getCorrFlag() Calibrated StartX – StartY  150ps sigma BUT: Works only if the time separation of beam particles is greater than 3 ns !! Improvement: old method (first Start Hit taken) vs new approach (T0 selected based on TOF/RPC hits)  method works correctly HADES Collaboration Meeting XXV, GSI, Darmstadt, 19-22 November 2012.

  13. Start detector analysis – problem with T0 Limitations of the method based on TOF/RPC and Start: Works only if the time separation of beam particles is greater than 3 ns !! Still wrongly determined T0. Event selection: At least 5 protons in RPC with time larger than 1.5 ns (10-4) Plots from P.Tlusty • We will mark such cases in StartHitFinder (more than 1 hit within 3ns window) by adding an additional flag: 3 or -2 Ultimate method should be based on fully reconstructed tracks (G. Kornakov) Reconstructed T0 from all tracks in single event compared to T0 from the Start detector Fit result based on 1/sqrt(N) contribution from tracking and constant contribution from Start detector. σ(Start)=60ps To be implemented in HYDRA – high level analysis. HADES Collaboration Meeting XXV, GSI, Darmstadt, 19-22 November 2012.

  14. Outlook (1) • Start detector for pion beam  segmented, high rate, diamond detector for MIPs. - Small size detector ready (4.7 mm x 4.7 mm). 10 mm x 10 mm – needed. - Time resolution should be improved from 110ps  50ps Diamonds as timing detectors for minimum-ionizing particles ....J.Pietraszko et al. . NIM A 618 (2010) 121 - 123. • Start detector for heavy ions  low quality metallization reduce det. efficiency – metallization has to be improved 3. Start detector for FAIR (HADES/CBM)  high rate experiments (109 HI beam particles) : decent segmentation + fast readout electronics (TRB3) Real Time Conference (RT), 2010 17th IEEE-NPSS HADES Collaboration Meeting XXV, GSI, Darmstadt, 19-22 November 2012.

  15. Outlook (2) 4. High rate, high charge resolution measurement (Diamond, ECal, MDC, ....) Large jitter of the integrator width (charge) due to high gain for low frequency noise After walk correction via leading edges:  Charge Resolution:0.17 % HADES Collaboration Meeting XXV, GSI, Darmstadt, 19-22 November 2012.

  16. Thank you HADES Collaboration Meeting XXV, GSI, Darmstadt, 19-22 November 2012.

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