1 ACCULINNA Group, FLNR JINR, Dubna Russia ( & Lund 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 mm10 by 10 mm Resistance – 8 k  4 k  Front layer materials: RTV, Epotex301, Bicron, Naked Radiation flux: Light charged particles (E=1-25 AMeV)2 × /cm 2 Fast and slow neutrons5 × /cm 2

2 Test of CsI detection response for 179 MeV tritons 2 Si strip 61x61x1mm 3 detectors followed by 25x25x50mm 3 CsI earlier warning on effectiveness of full energy deposition for CsI

3 Conditions: I initial (U=50V) = 2-3 nA DE/E=2.5% (5.8 MeV) Air, T = 22 o  1 o C Intensity: <10 4 pps/cm 2 Time: ~ 60 days

4 Beam components: 8 He (99%) & 3 H (1%) Dimension – 25 mm on a D 2 gas target

5

6 few hours after irradiation

7 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 S Area5x5 mm 2 10x10 mm 2 I dark 5 nA 10 nA C term 80 pF 270 pF (according to authors the beam rate of 9×10 12 protons/cm 2 is equivalent to 2×10 13 of 1 MeV neutrons/cm 2 ) Jump of I dark (5  10 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

8 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%

9 Conclusions 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. 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.