High Dose Irradiation of Possible FCAL Sensors at the S-DALINAC

Ch.Grah

Physics and Detector MeetingDESY HH, 29.6.2006

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ContentsReminder of FCAL detector systems

and motivationTestbeam at the S-DALINAC of the TU

Darmstadt (12.06. -19.06.2006)•Preparations

•Some pictures from the testbeamAnalysis and first resultsSummary

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FCAL System

LumiCal30 layer Si:W26 < θ < 155 mrad

BeamCal30 layer CVD diamond:W5 < θ < 28 mrad

Forward region of LDC (V2)

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Sensors for FCAL

Energy deposition from beamstrahlung pairs in BeamCal.10-20 TeV and more depending on the beam parameters.

Dose of up to 10MGy/a

Investigate:• pCVD diamond sensors fromdifferent manufacturers (E6, IAF, Minsk)• Si sensors• GaAs sensors

pCVD sensor from IAF12 x 12 mm2 size, 300-500μm thickness,Ti/Pt/Au metallization

IAF: Fraunhofer Institute for Applied Solid-State PhysicsE6: De Beers Industrial Diamonds rebranded to Element Six in 2002pCVD: polycrystaline Chemical Vapour Deposition

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Radiation Hardness of CVD diamonds

In our lab: so far only low dose irradiation

diamond response vs. absorbed dose (Sr90)

T.Behnke et al., 2001

„pCVD diamonds are radiation hard.“

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Testbeam Purpose: High Dose Irradiation

Irradiate different sensor samples to high doses (>1 MGy). Use rather low energetic electrons similar to secondaries.

2X0 6X0 20X0

V.Drugakov

Energy spectrum of particles depositing energy in the BeamCal sensors

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S-DALINAC of the TU Darmstadt

Using the injector line of the S-DALINAC:10 ± 0.015 MeV and beam currents from 10 to 100 nA

3 GHz electron beamenergy: 2.5 to 130 MeVintensity: 1 nA to 50 µA

Superconducting DArmstadt LInear ACcelerator

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Accelerator Hall

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S-DALINAC Location

CCD setup

Periodic Charge Collection Distance measurement

Remote control/surveillance of beam area

Beam Areasee next slide

Transport of sensor under HV

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Beam Area

Monitor beam current via Faraday cup current to estimate dose. Monitor high voltage/current and temperatures. Local DAQ PC is operated remotely.

Optimization by G4 simulation

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G4 Simulation

Optimize distance

Optimize collimator andFaraday cup size

Reduce distance to exit window

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G4 Simulation

Energy deposition in the sensor Spatial distribution of sensor hits

Statistics (extract R = NFC/NSensor = 0.98)

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Sensor Holder

exit windowof beam line

collimator (IColl)

sensor box (IDia, TDia, HV)

Faraday cup (IFC, TFC)

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Beam Area: Equipment

Power supplies and monitoring Surveillance from control room

Sensor holder

I-V conversion

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Beam Area: Sensor (De-) Installation

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CCD Setup Installation

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CCD Setup Operation

typical spectrum of an E6 sensor

Sr90 source

Preamplifier

Sensor box

Trigger box

&Gate

PA

discr

discr

delay

ADC

Sr90

diamond

Scint. PM1

PM2

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Program

•2 samples from E6•1 MGy•5 MGy

•2 samples from IAF•1 MGy•5 MGy

•2 Si samples•both drew high currentsafter ~50 kGy.

E6_4p after ~5 MGy

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Analysis and First Preliminary Results

Tuned the beam to currents in the Faraday cup of:10, 20, 50 and 100 nA

This corresponds to dose rates of:59, 118, 296, 591 kGy/h

For now assume an error of 10%.

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Conclusion Investigated the radiation hardness of sensors

(silicon and pCVD diamond) for the calorimeters of the FCAL system of the ILC.

The S-DALINAC offers an infrastructure for irradiating with a wide range of intensities and energies up to 10 MeV.

Irradiated 6 samples up to doses of 1-5 MGy (at least for the diamond sensors).

Analysis is ongoing. Have the opportunity to repeat such a test next

year, to irradiate to even higher doses. There were some issues (beam monitoring during

irradiation, sensor box design) which will be improved by then.

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The Testbeam Crew

not on the photo:W.Lange

Thanks to: INTAS and the TU Darmstadt