View source for September 4, 2007 - Cosmic Telescope

{| border="1" cellpadding="20" cellspacing="0"
! colspan="2"|Plateau Zeroing
|-
|Time Start
|Time Stop
|Time elapsed (min.)
|Thresholds on both Scintillators
|Singles Count (on top)
|Coinc. Counts
|Coinc. per minute
|Angle measure
|-
|1:35 pm on 8/31
|1:10 pm on 9/04
|5725 min
|225
|626816
|1654
|.2889
|75 degrees
|}<br>

;Binomial distribtuion
; best example is a coin toss, its either heads or tails

; Poisson Distribution
: standard deviation (<math>\sigma</math>) = root of the mean (<math>\sqrt{\mu}</math>)
: use in counting experiments
: the distribtuion approximates the Binomial Distribution for the special case when the mean (<math>\mu</math>) is a lot less than the number of attempts to measure (<math>n</math>) because the probability of the event occurrring is small.
: In the cosmic ray telescope experiment the mean number of detected cosmic rays is much smaller than the number of cosmic rays passing by.

{| border="1" cellpadding="20" cellspacing="0"
|-
|Time Start
|Time Stop
|Time elapsed (hour)
|Singles Count (on top)
|Coinc. Counts
|Coinc. per hour
|<math>\sqrt{N}</math>
|<math>(x_i-\bar{x})^2</math>
|-
|1:20 pm || 2:20 pm ||1 ||5694 ||127 || 127 || 11.3 ||121
|-
|2:20 pm || 3:20 pm ||1 ||4896 ||136 || 136 || 11.6 ||4
|-
|3:20 pm || 4:20 pm ||1 ||4655 ||151 || 151 || 12.2 ||169
|}<br>

Mean <math>\mu</math> = 138 counts per hour

Instrumental Uncertainty =<math>\sigma = \sqrt{\frac{\sum (x_i - \bar{x})^2}{N-1}} = 12.12</math> counts per hour

Your instrumental uncertainty is approximately equal to the Poisson sigma (<math>\sqrt{138}= 11.7</math>) counts per hour.