June, 6, 2007 Scintillator Signals from source

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Today Oleksiy, Tamuna, and Tony looked at the scintillator response to a Californium (252Cf :1 [math]\mu[/math]g emmits 1.7E8 neutrons/min ) neutron source. Two types of PMTs were used each with different scintillators. PMTs were (i) ORTEC 266 and (ii) PHOTONIS VD 119. A voltage of 700 Volts (the base drew 500 [math]\mu[/math]A) was applied to the ORTEC PMT and 1200 Volts (the base drew 800 [math]\mu[/math]A)to the Photonis.

The Cf-252 was placed first at the distance ~0 cm to the front edge of scintillators. (i) Signal amplitude was ~8 mV at the threshold set on the oscilloscope 2.4 mV. (ii) Signal amplitude was ~20 mV.

In the case the distance between Cf-252 and scintillators was ~3 m we had only cosmic rays events in both channels.

Material of scintillator used in case (i) was BC-420.

Our next step is to install a scaler and attempt to measure rates.