Polycrystalline CVD Diamonds for the Beam Calorimeter of the ILC C. Grah 1 , U. Harder 1 , H. Henschel 1 , E. Kouznetsova 1 , W. Lange 1 , W. Lohmann 1 , M. Ohlerich 1,3 , R. Schmidt 1,3 , K. Afanaciev 2 , A. Ignatenko 2 N18-6, Tuesday, Oct. 31 st 1 Linear Collider, DESY, Zeuthen, Germany 2 NCPHEP BSU, Minsk, Belarus 3 BTU Cottbus, Germany
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Polycrystalline CVD Diamonds for the Beam Calorimeter of the ILC C. Grah 1, U. Harder 1, H. Henschel 1, E. Kouznetsova 1, W. Lange 1, W. Lohmann 1, M.
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Polycrystalline CVD Diamonds for the Beam Calorimeter of the ILC
C. Grah1, U. Harder1, H. Henschel1, E. Kouznetsova1, W. Lange1, W. Lohmann1, M. Ohlerich1,3, R. Schmidt1,3, K.
Linearity Test at CERN PSHadronic beam, 3 & 5 GeVFast extraction mode ~104-107 particles / ~10 ns
ADCsignal gate
10 ns
17 s
Diamond
Setup
Beam
Scint.+ PMTs.
Response of diamond sensor to beam particles (no preamplifier/attenuated)
Photomultiplier signals
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Response vs. Particle Fluence
30% deviation from a linear response for a particle fluence up to ~106 MIP/cm2
The deviation is at the level of the systematic error of the fluence calibration.
E64 FAP2
Fraunhofer IAFElement Six
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High Dose Irradiation
Irradiation up to several MGy using the injector line of the S-DALINAC:10 ± 0.015 MeV and beam currents from 10 to 100 nA corresponding to about 59 to 590 kGy/h
Superconducting DArmstadt LINear ACceleratorTechnical University of Darmstadt
Energy spectrum ofshower particles in BeamCal
V.Drugakov
2X0
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Preparations and Programme
GEANT4 simulation of the geometry
=> R = NFC/NSensor = 0.98
<Edep>/particle = 5.63 MeV/cm
Beam setup Sample Thickness, µm
Dose, MGy
E6_B2 (E6) 500 >1
DESY 8 (IAF) 300 >1
FAP 5 (IAF) 470 >5
E6_4p (E6) 470 >5
Apply HV to the DUT
Measure CCD ~20
min
Irradiate the sample~1 hour
CCD: Charge Collection Distance
collimator
preamp box
absorber
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Realization: Beam Setup
exit windowof beam line
collimator (IColl)
sensor box (IDia, TDia, HV) Faraday cup (IFC, TFC)
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CCD Setup
typical spectrum of an E6 sensor
Sr90 source
Preamplifier
Sensor box
Trigger box
&Gate
PA
discr
discr
delay
ADC
Sr90
diamond
Scint. PM1
PM2
Setups partly financed by EUDET.
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Results: CCD vs. Dose
100 nA (E6_4p) 100 nA (FAP5)
Silicon starts to degrade at 30 kGy.High leakage currents.Not recoverable.
CCD = Qmeas/Qinduced x thicknessBias voltage = 400V ≈> 1 V/μm
After absorbing 7MGy:
CVD diamonds still operational.
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Behaviour after Irradiation
Slight increase of currents forhigher doses.
No significant change of the current-voltage characteristics up to 1.5 MGy.
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CCD Behaviour after Irradiation
after 1.5 MGy
~ -30%
~ -80%
after 7 MGy
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After Irradiation: IAF Sample
strong „pumping“ behaviour.
before/after ~ 7MGy
signal recovery after 20 Gy
▪ FAP 5 irradiated, 1st measurement
▪ FAP 5 irradiated, additional 20 Gy
▪ before irradiation ▪ after irradiation
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Summary BeamCal is an important part of the instrumentation of
the very forward region of the ILC detectors. The requirements on the radiation hardness and linearity
of the sensors are challenging. PCVD diamonds are an interesting material for this task. The linearity of pCVD diamonds up to particle fluences of
106 particles/cm2/10ns is better than 30%. High dose irradiation using 10MeV electrons shows:
all CVD diamonds stay functional even after absorbing up to 7MGy.
degradation of the signal at high doses and dose rates. partial recovery of the signal after absorbing additional small
doses (~20 Gy). wide variation of the signal sizes as a function of the
absorbed dose is an issue for the use as a sensor for BeamCal.