Properties of scCVD diamonds irradiated with a high intensity Au beam

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Properties of scCVD diamonds irradiated with a high intensity Au beam

Jerzy Pietraszkoa , W. Koeniga, Trägera for the HADES Collaboration

a GSI Helmholtz Centre for Heavy Ion Research GmbH Planckstrasse 1, D-64291 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 CBM @ SIS300

- fast readout electronics

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The HADES detector at GSI

azimuth. symmetry

large coverage: y = 0 - 2

hadron & lepton PID

2% mass resolution

LVL2 lepton trigger

forward wall

http://www-hades.gsi.de

[email protected] GeV

e+e−

ToF measurement

essential part of

particle identification

(T0 determination)

diamond detector

Au+Au

ADAMAS 1st Workshop, GSI, Darmstadt, 16-18 December 2012

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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

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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 detector45 cm

Veto detector, pcCVD reference detector

10 mm

4,7 mm

Start detector

scCVD

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Signal characteristics for Au ions @ 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


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Start-Veto system readout electronics Issues:

High rate, up to 107/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


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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: 106/s per channel

Long term stability problem – increasing off-spill current

Effect clearly visible after 2-3 hours of continuous Au beam with intensity 106/s (/ mm2) Observed for scCVD and pcCVD diamond materialsTime Start current in spill Start current off spill Veto current in spill Veto current off spill

10:00 2.5 A 0.00 A 2.6 A 0.00 A

11:39 2.5 A 0.09 A 2.6 A 0.04 A

12:01 1.4 A 0.88 A 1.8 A 0.20 A

12:41 2.2 A 0.88 A 2.4 A 0.40 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 1st Workshop, GSI, Darmstadt, 16-18 December 2012

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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 ch5 St ch6

St ch7 St ch8 HPTDC 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 1st Workshop, GSI, Darmstadt, 16-18 December 2012

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Five days with Au beam (Au 2011)Dismounted Start detector:

Beam spot

0.8x1.6 mm2

1.28 mm2

0.8 mm

M. Träger, GSI Det.Lab

X-ray Microanalysis (EDX)

No damage to the Au metalization surface visible

Electron microscope

GSI Target. Lab


Au beam properties at SIS 18measuerd with a strip detectror

Beam profile in X and Y directions

3σy = 1.26 mm 3σx = 0.97 mm


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Five days with Au beamTotal dose during 5 days measured in the Start detector

1.9 x 10 11 Au ions

+ 30 % DAQ off + 30 % beam times in 2010

3.04 x 1011 Au ions / 1.0 mm2

3.04 x 1011 Au ions / mm2

inner segments outer segments

ADC spectra: Pu239 - Am241 - Cm244 in vacuum (5.157 MeV, 5.486 MeV, 5.804 MeV)

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M. Träger, GSI Det.Lab


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Start detector efficiency determination

Strong eff. changes correlated with shifts in beam position !!

0.70 x 1011 Au ions / mm2 3.04x 1011Au ions / mm2


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Radiation hardness study with Au beam - amplitude reduction

Threshold characteristics (Aug11): cut amplitudes lower than 35mV

Analog signals, Au beam, HV: 100VAmplitude; 94 mV

After 3.04 x 1011 Au ions /mm2 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


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Start detector time resolution ( after 3.04 x 1011 Au ions / mm2, 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 !


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- 16 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


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 - 128 channels Time, ToT, 25ps/bin - 32 channels Rate capability: up to 3 MHz per

channelAll channels show RMS below 25ps/1.4 = 17.8 ps

Eugen Bayer, Michael TraxlerReal Time Conference (RT), 2010 17th IEEE-NPSS

New development available:


T0 detector and beam quality monitor for FAIR (HADES/CBM) high rate experiments (109 HI beam particles) :

decent segmentation + fast readout electronics (TRB3)

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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 %


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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Start-Veto system forHADES pion/proton experiment (MIPs)

Experimental conditions and requirements for HADES pion experiment: Secondary pion beam, mom.=1GeV/c (MIPs) scCVD Demanding beam particles intensity >106 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) 121-123

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Start-detector for MIPs – test with p beamJuelich 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

TD

iff

TD

iff

ToT ToT

after ToT cut

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The Multipurpose Trigger Readout Board TRBTRB 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 - 128 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

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Beam position monitoring

Precise position information

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Properties of scCVD diamonds irradiated with a high intensity Au beam

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