View source for 05/11/2011 neutron detector threshold calibration

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Because is something wrong I decided to measure the counts rate as function of threshold energy. Maybe my threshold was incorrect.

Below are my results for n's detector with HAMAMATSU PMT (-1500 V):

[[File:Det1 callibration.png | 1000 px]]



So it looks like my previous threshold value (-500 mV) was not good. '''Let's set it up the -200 mV.''' And let's see does the n's detector sensitive to the source. The same set up and distances as before.
{| border="1" cellspacing="0" style="text-align: center; width: 800px; height: 100px;"
! scope="col" width="50" | 
! scope="col" width="50" | counts/sec (5 min test), no source
! scope="col" width="50" | counts/sec (5 min test), with source on the top of PS1
|-
!n's 
|19.89<math>\pm</math>0.26   (total 5966 cnts) || 58.84<math>\pm</math>0.29   (total 17652 cnts) 
|}

So now we see the source. The ratio are:

 <math>\frac{Rate_{source}}{Rate_{w/source}} = \frac{58.84}{19.89} = 2.96 </math>