Difference between revisions of "05/12/2011 random coincidence cosmic test"

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[https://wiki.iac.isu.edu/index.php/N%27s_detector_calibration Go Back]
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[https://wiki.iac.isu.edu/index.php/Roman_measurements go back]
  
  
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The powers are:
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The voltages, thresholds and widths are:
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{| border="1" cellspacing="0" style="text-align: center; width: 800px; height: 100px;"
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! scope="col" width="50" |
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! scope="col" width="50" | PMT voltage, V
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! scope="col" width="50" | threshold, mV
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! scope="col" width="50" | discr. width, ns
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|-
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!PS1
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| -1000|| -80|| 20
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|-
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!PS1
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| -1000|| -80|| 10
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|}
  
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PS1 and PS2:  -1000 V (the old 2-channel TENNELEC TC952)
 
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n's: -1100 V (the new 2-channel C.A.E.N N471)
 
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The thresholds are:
 
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PS1 and PS2:  -80 mV
 
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n's: -200 mV
 
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The discriminator widths are:
 
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PS1: -20 ns
 
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PS2: -10 ns
 
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n's: -20 ns
 
  
  
 
Let's do the '''random coincidence cosmic ray test 1'''.
 
Let's do the '''random coincidence cosmic ray test 1'''.
  
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PS1 and PS2 is about 30 cm away from each other. And let's look on the coincidence signal between PS1 and PS2:
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PS1 and PS2 is about 30 cm away from each other. Let's look on the coincidence signal between PS1 and PS2.
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{| border="1" cellspacing="0" style="text-align: center; width: 800px; height: 100px;"
+
{| border="1" cellspacing="0" style="text-align: center; width: 1000px; height: 100px;"
 
! scope="col" width="50" |  
 
! scope="col" width="50" |  
 
! scope="col" width="50" | total counts
 
! scope="col" width="50" | total counts
 
! scope="col" width="50" | time
 
! scope="col" width="50" | time
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! scope="col" width="50" | counts/min
 
 
! scope="col" width="50" | counts/sec
 
! scope="col" width="50" | counts/sec
 
|-
 
|-
 
!PS1  
 
!PS1  
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|<math>10247\pm101.2</math>||70 min||<math>146.4\pm1.44</math>||<math>2.44\pm0.02</math>
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|<math>10247\pm101.2</math>||70 min||<math>2.44\pm0.02</math>
 
|-
 
|-
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!PS1  
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!PS1 (May 13)
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|<math>12969\pm113.9</math>||70 min||<math>185.3\pm1.63</math>||<math>3.09\pm0.03</math>
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|<math>12178\pm110.3</math>||80 min||<math>2.54\pm0.02</math>
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|-
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!PS2
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|<math>12969\pm113.9</math>||70 min||<math>3.09\pm0.03</math>
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|-
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!PS2 (May 13)
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|<math>14674\pm121.1</math>||80 min||<math>3.06\pm0.03</math>
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|-
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!PS1+PS2
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|<math>3\pm1.7</math>||70 min||<math>(0.7\pm0.4)\cdot 10^{-3}</math>
 
|-
 
|-
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!PS1+PS2 (30 cm away)
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!PS1+PS2 (May 13)
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|<math>3\pm1.7</math>||70 min||<math>0.043\pm0.024</math>||<math>0.0007\pm0.0004</math>
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|<math>11\pm3.3</math>||80 min||<math>(2.3\pm0.7)\cdot 10^{-3}</math>
 
|}
 
|}
  
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[[File:Rnd coinc cosmic.png | 800px]]
 
[[File:Rnd coinc cosmic.png | 800px]]
 +
 +
Here the questions: All coincidences are true and caused by detectors or maybe some of them are false and caused by electronics (Tamuna said I need to subtract 3-4 coincidences from total 11 for 80 min test because she did something with electronics at that time)
 +
  
  
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But now the distance between PS1 and PS2 is about 5 cm. And let's look on the coincidence signal between PS1 and PS2:
 
But now the distance between PS1 and PS2 is about 5 cm. And let's look on the coincidence signal between PS1 and PS2:
−
{| border="1" cellspacing="0" style="text-align: center; width: 800px; height: 100px;"
+
{| border="1" cellspacing="0" style="text-align: center; width: 1000px; height: 100px;"
 
! scope="col" width="50" |  
 
! scope="col" width="50" |  
 
! scope="col" width="50" | total counts
 
! scope="col" width="50" | total counts
 
! scope="col" width="50" | time
 
! scope="col" width="50" | time
−
! scope="col" width="50" | counts/min
 
 
! scope="col" width="50" | counts/sec
 
! scope="col" width="50" | counts/sec
 
|-
 
|-
 
!PS1  
 
!PS1  
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|<math>\pm</math>||70 min||<math>\pm</math>||<math>\pm</math>
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|<math>9101\pm95.4</math>||60 min||<math>2.53\pm0.03</math>
 
|-
 
|-
 
!PS1  
 
!PS1  
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|<math>\pm</math>||70 min||<math>\pm</math>||<math>\pm</math>
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|<math>11394\pm106.7</math>||60 min||<math>3.16\pm0.03</math>
 
|-
 
|-
 
!PS1+PS2 (5 cm away)
 
!PS1+PS2 (5 cm away)
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|<math>\pm</math>||70 min||<math>\pm</math>||<math>\pm</math>
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|<math>8\pm2.8</math>||60 min||<math>(2.2\pm0.8)\cdot 10^{-3}</math>
 
|}
 
|}
  
  
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And below my scope pictures of no so rear event as before:
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And below my scope pictures of this rear event as before:
  
 
[[File:Rnd coinc cosmic test2.png | 800px]]
 
[[File:Rnd coinc cosmic test2.png | 800px]]
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So what we are measured?  
 
So what we are measured?  
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:<math>&copy</math> purely random events from different reaction?. But why does rate depend from distance?
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:○ purely random events from different reaction?. But why does the coincidence rate depend from distance between PS1 and PS2? Statistical fluctuation? Electronic false events?
−
:&copy some coincidences are sub-products of one reaction? (air showers). Now if detectors located closer to each other the rate should be higher because the detectors are closer to initial reaction.
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:○ or probably some coincidence events caused by air shower originated from one particle nearby the two detectors. Now if detectors located closer to each other the rate should be higher because the detectors are closer to initial particle. As evidence note that rates for PS1 and PS1 for different distances are almost the same. But the coincidence rate PS1+PS2 increased almost in 3 times as distance reduced from 30 cm to 5 cm. (That need to be studied)
 +
 
 +
Also Sadiq did something  at that time with gamma source. Maybe that effected somehow my measurements.

Latest revision as of 19:00, 24 May 2012

go back


The voltages, thresholds and widths are:

PMT voltage, V threshold, mV discr. width, ns
PS1 -1000 -80 20
PS1 -1000 -80 10


Let's do the random coincidence cosmic ray test 1.

PS1 and PS2 is about 30 cm away from each other. Let's look on the coincidence signal between PS1 and PS2.

total counts time counts/sec
PS1 [math]10247\pm101.2[/math] 70 min [math]2.44\pm0.02[/math]
PS1 (May 13) [math]12178\pm110.3[/math] 80 min [math]2.54\pm0.02[/math]
PS2 [math]12969\pm113.9[/math] 70 min [math]3.09\pm0.03[/math]
PS2 (May 13) [math]14674\pm121.1[/math] 80 min [math]3.06\pm0.03[/math]
PS1+PS2 [math]3\pm1.7[/math] 70 min [math](0.7\pm0.4)\cdot 10^{-3}[/math]
PS1+PS2 (May 13) [math]11\pm3.3[/math] 80 min [math](2.3\pm0.7)\cdot 10^{-3}[/math]


And below my scope pictures of this rear event:

Rnd coinc cosmic.png

Here the questions: All coincidences are true and caused by detectors or maybe some of them are false and caused by electronics (Tamuna said I need to subtract 3-4 coincidences from total 11 for 80 min test because she did something with electronics at that time)


Let's do the random coincidence cosmic ray test 2.

But now the distance between PS1 and PS2 is about 5 cm. And let's look on the coincidence signal between PS1 and PS2:

total counts time counts/sec
PS1 [math]9101\pm95.4[/math] 60 min [math]2.53\pm0.03[/math]
PS1 [math]11394\pm106.7[/math] 60 min [math]3.16\pm0.03[/math]
PS1+PS2 (5 cm away) [math]8\pm2.8[/math] 60 min [math](2.2\pm0.8)\cdot 10^{-3}[/math]


And below my scope pictures of this rear event as before:

Rnd coinc cosmic test2.png


So what we are measured?

○ purely random events from different reaction?. But why does the coincidence rate depend from distance between PS1 and PS2? Statistical fluctuation? Electronic false events?
○ or probably some coincidence events caused by air shower originated from one particle nearby the two detectors. Now if detectors located closer to each other the rate should be higher because the detectors are closer to initial particle. As evidence note that rates for PS1 and PS1 for different distances are almost the same. But the coincidence rate PS1+PS2 increased almost in 3 times as distance reduced from 30 cm to 5 cm. (That need to be studied)

Also Sadiq did something at that time with gamma source. Maybe that effected somehow my measurements.

Retrieved from "https://wiki.iac.isu.edu/index.php?title=05/12/2011_random_coincidence_cosmic_test&oldid=74558"