1 Properties of scCVD diamonds irradiated with a high intensity Au beam Jerzy Pietraszko a, W. Koenig a, Träger a for the HADES Collaboration a GSI Helmholtz Centre for Heavy Ion Research GmbH Planckstrasse 1, D Darmstadt, Germany  T0 detector and beam monitoring reqirements for Au+Au experiment in HADES  Au beam properties at SIS 18  Radiation hardness tests of scCVD diamond detector  scCVD diamond detector with strip metalization in Apr 2012  Outlook: -CBM/HADES at SIS100 and SIS300 -fast readout electronics

22 The HADES detector at GSI  azimuth. symmetry  large coverage: y =  hadron & lepton PID  2% mass resolution  LVL2 lepton trigger  forward wall     GeV   e + e − ToF measurement essential part of particle identification (T0 determination)  diamond detector Au+Au ADAMAS 1 st Workshop, GSI, Darmstadt, December 2012

3 HADES Start-Veto system (Au+Au) Detector requirements: Low material budget (low interaction probability), good time resolution (below 50 ps) In vacuum operation, located directly in front of the target in order to reduce load on the RICH  Start det.: monocrystalline diamond, 70  m thickness, 4.7mm x 4.7mm  Veto det.: polycrystalline diamond, 100  m thickness, behind the RICH Detector. Start - Halo 4,7 mm 15 gold targets (Ø 2.2 mm) Start detector mm ADAMAS 1 st Workshop, GSI, Darmstadt, December 2012

4 HADES Start-Veto system (Au+Au)  Start det.: monocrystalline diamond, 70  m thickness, 4.7mm x 4.7mm  Veto det.: polycrystalline diamond, 100  m thickness, behind the RICH Detector. 15 gold targets (Ø 2.2 mm) Veto detector Start detector 45 cm Veto detector, pcCVD reference detector 10 mm 4,7 mm Start detector scCVD mm ADAMAS 1 st Workshop, GSI, Darmstadt, December 2012

Signal characteristics for Au 1.23 AGeV E. Berdermann et al., „First applications of CVD diamonds...”, Como 1998 pcCVD  Reduction of the effective field due to the large space charge produced by heavy ions  Optimal working point for Au beam: 6-7 V/µm ADAMAS 1 st Workshop, GSI, Darmstadt, December 2012

6 Start-Veto system readout electronics Issues: High rate, up to 10 7 /s per channel. Fast signals, analog signal from diamond – 200 ps rise time, base width < 1ns. Our approach: Dedicated NINO based discriminator board with trigger functionality. Time measurement performed by HADES TRB board – based on HPTDC. NINO-based board NINO chip: Developed for Time-of-flight measurements in the ALICE experiment Key features: Adjustable discriminator thresholds. Front end time jitter <10ps. Sustains very high rate (>>10MHz) Peaking time: 1ns. Input signal range: 30fC - 2pC. Noise: <2500 e-. Discriminator threshold: 10fC - 100fC. Timing precision: <10ps jitter. Output: LVDS. 8 x input signals 8 x scaler/trigger output signals 8 x LVDS timing output signals ADAMAS 1 st Workshop, GSI, Darmstadt, December 2012

7 scCVD with high intensity Au beam stability problem ! Setup and conditions: Start det.: monocrystalline diamond, 70  m thickness, HV set to 200 V. Veto det.: polycrystalline diamond, 100  m thickness, HV set to 200 V. Beam particles intensity: 10 6 /s per channel Long term stability problem – increasing off-spill current Effect clearly visible after 2-3 hours of continuous Au beam with intensity 10 6 /s (/ mm 2 ) Observed for scCVD and pcCVD diamond materials TimeStart current in spillStart current off spillVeto current in spillVeto current off spill 10:  A0.00  A2.6  A0.00  A 11:  A0.09  A2.6  A0.04  A 12:  A0.88  A1.8  A0.20  A 12:  A0.88  A2.4  A0.40  A...  Strong dependence on the HV observed: example: 200 V – 0.25  A 150 V – 0.08  A could not stand 4-5 weeks of Au+Au production run in HADES !!!!  Stable long term operation at 1.4 V/µm ADAMAS 1 st Workshop, GSI, Darmstadt, December 2012

8 Start-Veto system – test with Au beam, time resolution at 1V/  m (HV = 50 V) St ch1 41 ps St ch2 35 ps St ch3 38 ps St ch4 35 ps St ch5St ch6 St ch7 St ch8HPTDC resolution HV reduced by a factor of 4 (200 V  50 V) - the time resolution below 50 ps  expected stable long term operation during high intensity HI run ! ADAMAS 1 st Workshop, GSI, Darmstadt, December 2012

9 Five days with Au beam (Au 2011) Dismounted Start detector: Beam spot 0.8x1.6 mm 2  1.28 mm mm M. Träger, GSI Det.Lab X-ray Microanalysis (EDX) No damage to the Au metalization surface visible Electron microscope GSI Target. Lab ADAMAS 1 st Workshop, GSI, Darmstadt, December 2012

Au beam properties at SIS 18 measuerd with a strip detectror Beam profile in X and Y directions 3σ y = 1.26 mm3σ x = 0.97 mm ADAMAS 1 st Workshop, GSI, Darmstadt, December 2012

11 Five days with Au beam Total dose during 5 days measured in the Start detector 1.9 x Au ions + 30 % DAQ off + 30 % beam times in 2010  3.04 x Au ions / 1.0 mm 2  3.04 x Au ions / mm 2 inner segments outer segments ADC spectra: Pu239 - Am241 - Cm244 in vacuum (5.157 MeV, MeV, MeV) mm M. Träger, GSI Det.Lab ADAMAS 1 st Workshop, GSI, Darmstadt, December 2012

12 Start detector efficiency determination  Strong eff. changes correlated with shifts in beam position !! 0.70 x Au ions / mm x Au ions / mm 2 ADAMAS 1 st Workshop, GSI, Darmstadt, December 2012

13 Radiation hardness study with Au beam - amplitude reduction Threshold characteristics (Aug11): cut amplitudes lower than 35mV Analog signals, Au beam, HV: 100V Amplitude; 94 mV  After 3.04 x Au ions /mm 2 about 5% of signals below 35 mV  Total absorbed dose : 7.9 Grad (312 MeV / Au ion)  Amplitude reduction by a factor of 2.7  Precise CCE measurment needed ADAMAS 1 st Workshop, GSI, Darmstadt, December 2012

14 Start detector time resolution ( after 3.04 x Au ions / mm 2, 7.9 Grad ) difficult conclusions: the right picture measured for signals very close to the discriminator threshold level (large time jitter)  worsening comes from electronics ! ADAMAS 1 st Workshop, GSI, Darmstadt, December 2012

stripes on each side -strip width: 200µm -gap: 90 µm -thickness about 60 µm Highly segmented diamond sensor – excellent beam diagnostic capabilities – used in Apr 2012 (5 weeks Au beam) 4.39 mm Beam profile in X and Y directions ADAMAS 1 st Workshop, GSI, Darmstadt, December 2012

Outlook: Fast readout electronics TRB 2 Board: 4 TDC – 128 channels (HPTDC), 4x512Mb SDRAM, FPGA – Virtex4LX40, ETRAX, FS – 4 processors, 100Mb/s,TCP/IP, 2,5 Gb/s optical link, DSP TigerSharc, DC/DC converters, AddOn connector  Time, ToT, 96ps/bin channels  Time, ToT, 25ps/bin - 32 channels  Rate capability: up to 3 MHz per channel All channels show RMS below 25ps/1.4 = 17.8 ps Eugen Bayer, Michael Traxler Real Time Conference (RT), th IEEE-NPSS New development available: ADAMAS 1 st Workshop, GSI, Darmstadt, December 2012 T0 detector and beam quality monitor for FAIR (HADES/CBM)  high rate experiments (10 9 HI beam particles) : decent segmentation + fast readout electronics (TRB3)

17 Outlook: Fast readout electronics dE/dx 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 % ADAMAS 1 st Workshop, GSI, Darmstadt, December 2012

Thank you We highly appreciate the support of E. Berdermann et al. from the GSI Detector Laboratory and A. Hübner at al. from the GSI Target Laboratory for the detector preparation.

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20 Start-Veto system for HADES pion/proton experiment (MIPs) Experimental conditions and requirements for HADES pion experiment: Secondary pion beam, mom.=1GeV/c (MIPs)  scCVD Demanding beam particles intensity >10 6 pions/sec Secondary beam. Beam spot diameter 1-2 cm  Large area moncrystaline diamond Timing signal for Tof measurement and for trigger - 50 ps time resolution Prototype: 4.7 mm x 4.7 mm, monocrystalline: used for proton induced reactions NIMA 618 (2010)

21 Start-detector for MIPs – test with p beam Juelich proton beam, 2.95 GeV: Two Start det.: monocrystalline diamond, 500  m thickness, 4.7mm x 4.7mm, with halo functionality, 50nm Cr/150nm Au metallization. Stable operation at intensities > 10^6 protons/ s/channel, BEST TIME RES = 100 ps, expected 50ps TDiff ToT after ToT cut

22 The Multipurpose Trigger Readout Board TRB TRB Board: 4 TDC – 128 channels (HPTDC), 4x512Mb SDRAM, FPGA – Virtex4LX40, ETRAX, FS – 4 processors, 100Mb/s,TCP/IP, 2,5 Gb/s optical link, DSP TigerSharc, DC/DC converters, AddOn connector  Time, ToT, 96ps/bin channels  Time, ToT, 25ps/bin - 32 channels  Rate capability: up to 3 MHz per channel Pulser test signal sent to 8 channels. Individual INL corrections for each channel  All 32 channels show RMS below 25ps/1.4 = 17.8 ps ~1.5 m of cable

23 Beam position monitoring  Precise position information mm