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Radiation damage of 1600Pixel MPPC by neutrons. ILC-CAL meeting University of tsukuba H.Yamazaki. Dose rate. Flux = 1.5×10 9 neutron/cm 2 /Wh (W = watt, h = hour) …… calculated MCNP ( Monte Carlo Neutron and Photon Transport Code System ) Code. 4 dose rate patterns
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Radiation damage of 1600Pixel MPPC by neutrons ILC-CAL meeting University of tsukuba H.Yamazaki
Dose rate Flux = 1.5×109 neutron/cm2/Wh (W = watt, h = hour) …… calculated MCNP(Monte Carlo Neutron and Photon Transport Code System) Code 4 dose rate patterns ↓ 1.5×109 neutron/cm2 /Wh×12.5/60 h×1W =3.125×108 neutron/cm2 1.5×109 neutron/cm2 /Wh×12.5/60 h×10W =3.125×109 neutron/cm2 1.5×109 neutron/cm2 /Wh×12.5/60 h×100W =3.125×1010 neutron/cm2 1.5×109 neutron/cm2 /Wh×12.5/60 h×1kW=3.125×1011 neutron/cm2
Uniformity of Sample (Noise Rate,Cross-talk Probability ) Noise Rate (Vbias) Cross-talk Probability Noise Rate (Vover ) • Sample irradiated with 3.125×108n/cm2 • Sample irradiated with 3.125×109n/cm2 • Sample irradiated with 3.125×1010 n/cm2 • Sample irradiated with 3.125×1011 n/cm2 The individual difference of several percent was confirmed to four samples.
Measurement after the irradiation • Before the irradiation • 3.125×109 n/cm2 • 3.125×109 n/cm2 • Before the irradiation • 3.125×108 n/cm2 • 3.125×109 n/cm2 Noise Rate Cross-talk Probability (at Vbias = -77.5V) before 108 n/cm2 109 n/cm2 NoiseRate(Hz) 346,236 569,263 3,157,690 Increased of Noise Rate 160% 910% Crosstalk probability 0.158 0.144 0.171 Noise Rate rises as dose rate goes up, Cross-talk dose not change so much by irradiation
Measurement after the irradiation (3.125×108 n/cm2) several times measurement after irradiation Noise Rate Cross-talk Probability • 2007 11/14 Before irradiation • 11/16 Just after irradiation • 12/05 Before annealing at 60゜C • 12/06 After annealing at 60゜C • 12/15 The additional measurement 1 • 12/15 The additional measurement 2
Measurement after the irradiation( 3.125×109 n/cm2) several times measurement after irradiation Noise Rate Cross-talk Probabirity • 2007 11/14 Before irradiation • 11/16 Just after irradiation • 12/05 Before annealing at 60゜C • 12/06 After annealing at 60゜C • 12/15 The additional measurement 1 • 12/15 The additional measurement 2
Summary • Noise Rate rises as dose rate gose up • Cross-talk dose not change so much by irradiation • There are some problems for the noise rate measurement • Plan • Another analysis …….Gain,NoiseRate(Vbias correction),After Pulse