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Radiation hardness test of PD’s and APD’s, Energy resolution of CsI/PD and CsI/APD. ACCULINNA Group, FLNR JINR, Dubna Russia (http://aculina.jinr.ru) & Lund University, Sweden. Si PIN characteristics : Face size – 10.5 by 11.5 mm 10 by 10 mm Resistance – 8 k W 4 k W
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Radiation hardness test of PD’s and APD’s, Energy resolution of CsI/PD and CsI/APD ACCULINNA Group, FLNR JINR, Dubna Russia (http://aculina.jinr.ru)&Lund University, Sweden Si PIN characteristics : Face size – 10.5 by 11.5 mm 10 by 10 mm Resistance – 8 kW 4 kW Front 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
earlier warning on effectiveness of full energy deposition for CsI Test of CsI detection response for 179 MeV tritons 2 Si strip 61x61x1mm3 detectors followed by 25x25x50mm3 CsI
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 ΔE/E (%) of CsI/PD’safter an integrated flux of ~2×1010 LCP/cm2
Beam components: 8He (99%) & 3H (1%) Dimension – 25 mm on a D2 gas target Energy resolution after radiation (2×1010 LCP/cm2)ΔE (1 mm Si) vs. Eloss (CsI/PD) plots
Effect of irradiation by fast neutrons, 5 days after(Flux ~ 5×1011 n/cm2 at ACCULINNA - F2) few hours after irradiation
From literature: 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 PSI That could be dangerous for low energy gamma spectroscopy! KVI
Comparison of CsI/APD and CsI/PD energy resolution Eγ=0.66 MeV ΔE/E=5.8% ΔE/E=12.0% Eγ=1.33 MeV ΔE/E=4.8% ΔE/E=7.1%
Conclusions 1H • 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. • High energy γ will fire several CsI crystals. How to reconstruct from the neighbouring crystals (5-10?) the total energywith 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. γ Has each crystal its specific light-energy relation and has be calibrated individually by LCP and/or γ ?