05/11/2011: Difference between revisions

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So it looks like my previous threshold value (-500 V) was not good. Let's set it up the -200 V. And see what happens.
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.
 
 
The same set up as before, the distances are the same:
 
[[File:Detector1.png | 400px]]
 
 
 
First he CF-243 source is far far away (sealed in the safe):
{| border="1" cellspacing="0" style="text-align: center; width: 800px; height: 100px;"
{| border="1" cellspacing="0" style="text-align: center; width: 800px; height: 100px;"
! scope="col" width="50" |  
! scope="col" width="50" |  
! scope="col" width="50" | counts/min (1 min test)
! scope="col" width="50" | counts/sec (5 min test), no source
! scope="col" width="50" | counts/min (1 min test)
! scope="col" width="50" | counts/sec (5 min test), with source on the top of PS1
! scope="col" width="50" | counts/min (1 min test)
! scope="col" width="50" | counts/min (1 min test)
! scope="col" width="50" | avg counts/min
|-
!PS1
|
|-
!PS2
|
|-
|-
!n's  
!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:


Now the CF-243 source is on the top of PS1:
<math>\frac{Rate_{source}}{Rate_{w/source}} = \frac{58.84}{19.89} = 2.96 </math>
{| border="1" cellspacing="0" style="text-align: center; width: 800px; height: 100px;"
! scope="col" width="50" |
! scope="col" width="50" | counts/min (1 min test)
! scope="col" width="50" | counts/min (1 min test)
! scope="col" width="50" | counts/min (1 min test)
! scope="col" width="50" | counts/min (1 min test)
! scope="col" width="50" | avg counts/min
|-
!PS1
|378,893||378,612||377,909||378,665||'''378,519.7'''
|-
!PS2
|22,729||22,819||22,572||22,530||'''22,662.5'''
|-
!PS1+PS2
|1044||1021||1023||975||'''1015.7'''
|-
!n's
|200||210||228||219||'''214.2'''
|}

Latest revision as of 04:59, 12 May 2011

Go Back


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):


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.

counts/sec (5 min test), no source counts/sec (5 min test), with source on the top of PS1
n's 19.89[math]\displaystyle{ \pm }[/math]0.26 (total 5966 cnts) 58.84[math]\displaystyle{ \pm }[/math]0.29 (total 17652 cnts)

So now we see the source. The ratio are: 

[math]\displaystyle{ \frac{Rate_{source}}{Rate_{w/source}} = \frac{58.84}{19.89} = 2.96  }[/math]
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