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ACCULINNA Group, FLNR JINR, Dubna Russia ACCULINNA Group, FLNR JINR, Dubna Russia (http://aculina.jinr.ru)(http://aculina.jinr.ru)

&& Lund University, SwedenLund University, Sweden

Radiation hardness test of PD’s and APD’s,Energy resolution of CsI/PD and CsI/APD

Si PIN characteristics :Face size – 10.5 by 11.5 mm 10 by 10 mmResistance – 8 k 4 kFront layer materials: RTV, Epotex301, Bicron, Naked

Radiation flux:Light charged particles (E=1-25 AMeV) 2×1010 1/cm2

Fast and slow neutrons 5×1011 1/cm2

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Test of CsI detection response for 179 MeV tritons 2 Si strip 61x61x1mm3 detectors followed by 25x25x50mm3 CsI

earlier warning on effectiveness of full energy deposition for CsI

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Conditions:

Iinitial (U=50V) = 2-3 nA

DE/E=2.5% (5.8 MeV)

Air, T = 22o 1o C

Intensity: <104 pps/cm2

Time: ~ 60 days

Dark current values (nA) of PD’s and Dark current values (nA) of PD’s and ΔΔE/E (%) of CsI/PD’sE/E (%) of CsI/PD’safter an integrated flux of ~2after an integrated flux of ~2××10101010 LCP/cm LCP/cm22

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Beam components:

8He (99%) & 3H (1%)

Dimension – 25 mm

on a D2 gas target

Energy resolution after radiation (2Energy resolution after radiation (2××10101010 LCP/cm2) LCP/cm2) ΔΔE (1 mm Si) vs. Eloss (CsI/PD) plotsE (1 mm Si) vs. Eloss (CsI/PD) plots

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Effect of irradiation by fast neutrons, 5 days afterEffect of irradiation by fast neutrons, 5 days after(Flux ~ 5(Flux ~ 5××10101111 n/cm n/cm22 at ACCULINNA - F2) at ACCULINNA - F2)

few hours after irradiation

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Increase of the dark current of APD’s during irradiation with 70 MeV proton beam of PSI (top) and 90 MeV protons at KVI (bottom)

Prop. CMS PANDA-EMC

APD’s S8148 S8664-1010

Area 5x5 mm2 10x10 mm2

Idark 5 nA 10 nA

Cterm 80 pF 270 pF

(according to authors the beam rate of 9×1012 protons/cm2 is equivalent to 2×1013 of 1 MeV neutrons/cm2)

Jump of Idark (510 nA 4 μmA) takes place after an integrated flux of 5×1011 neutron/cm2

That could be dangerous for low energy gamma spectroscopy!

From literature:

KVI

PSI

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Comparison of CsI/APD and CsI/PD energy resolutionComparison of CsI/APD and CsI/PD energy resolution

E Eγγ=0.66 MeV =0.66 MeV ΔΔE/E=5.8% E/E=5.8% ΔΔE/E=12.0% E/E=12.0% E Eγγ=1.33 MeV =1.33 MeV ΔΔE/E=4.8% E/E=4.8% ΔΔE/E=7.1% E/E=7.1%

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ConclusionsConclusions• For single CsI there is a large loss of events of full energy

deposition for high proton energy (E > 200 MeV).• DE-E method for LCP identification will be ambiguous with

increasing energy. 11HH

γγ

Has each crystal its specific light-energy relation and has be calibrated individually by LCP and/or γ ?

• High energy γ will fire several CsI crystals. How to reconstruct from the neighbouring crystals (5-10?) the total energy with a good enough resolution ~3-5% ?

• Low energy γ spectroscopy will suffer from radiation damage of PD/APD and crystals activation.

• A simulation of a neutron field is desirable to estimate deterioration of energy resolution caused by the radiation.