## (Radiation and Geiger Counters) How to Separate Alpha, Beta, Gamma

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Background 38 CPM
Total 19,262 CPM *
Beta+Gamma 14,116 CPM *
Gamma 1,392 cpm *

* values shown minus background (e.g. 19300 CPM total becomes 19,262 CPM after 38 CPM removed)

This is how we figure it out:

Alpha = Total – Beta+Gamma
Beta = Beta+Gamma – Gamma
Gamma = Gamma

We can replace the words for real values from above:
Alpha = (19262 CPM) – (14116 CPM) = 5146 CPM
Beta = (14116 CPM) – (1392 CPM) = 12724 CPM
Gamma = (1392 CPM) = 1392 CPM

The results sum back to the total, which helps us check our work:
Alpha + Beta + Gamma = 5146 CPM + 12724 CPM + 1392 CPM = 19262 CPM
——————————————————————————————

Here’s that bit about the copper lol I added it for fun, but it is correct.
Sheilding HVL of Copper: 10.2 mm
Thickness of Sample: ~4mm
Most Common Energy of Gamma: 214Bi 609.31 keV at 44.8%
e^-log(2)4mm/10.2mm = 0.76199, where d/dx e^-((ln(2)/10.2mm)*x) = (4^((-2+x)/x) log(2))/x^2

## Simple Decay Equation – Example (Polonium 210)

Filed under Science

How to calculate the current activity of a source given the activity at one point, the time which has elapsed, and the decay constant.

Activity_now = Activity_then * e^-((ln2/halflife)*elapsed_time)

Now, enter into your calculator for activity of 1000Bq, halflife of 20min, and elapsed time of 40min:

1000 * e ^ – ( ( ln(2) / 20 ) * 40 ) )

Technetium 99m has a half life of 6.01 hours and transitions to normal Technetium 99 via the release of surplus energy in the form of a gamma photon at 140.21 keV

## Statistically Valid Detections

The basic idea comes from z-score * sqrt(2*background)

## Basic Isotope Identification (Gamma Spectroscopy)

All materials in this video are copyright of me. I created them all. The screen captures of the software are from Spectrum Techniques.

My Equipment:

Spectrometer: UCS30 – http://www.spectrumtechniques.com/spec_systems.htm
Sources: Cs137 – http://www.spectrumtechniques.com/disc&laminated_sources.htm

Gamma Energy Resources:

http://ie.lbl.gov/decay.html
http://simplynuclear.com/index.php?title=Common_Gamma_Energy

Thorium Hypothesis
Isotope Energy Branching Ratio
Actinium 228 13 keV 0.38
Thorium 232 *63.81 keV 0.00267
Thorium 228 84.37 keV 0.01266
Thorium 228 131.61 keV 0.001355
Thorium 228 166.41 keV 0.001075
Thorium 228 215.99 keV 0.00263
Actinium 228 *338.32 keV 0.113
Thallium 208 510.77 keV 0.226
Thallium 208 *583.19 keV 0.845
Bismuth 212 727.33 keV 0.0658
Actinium 228 911.21 keV 0.266
Actinium 228 968.97 keV 0.162

Uranium Hypothesis
Isotope Energy Branching Ratio
Uranium 238 13 keV 0.08
Uranium 235 19.59 keV 0.61
Thorium 234 92.38 keV 0.028
Thorium 234 92.8 keV 0.028
Uranium 235 143.76 keV 0.1096
Uranium 235 185.71 keV 0.572
Thorium 227 235.97 keV 0.123
Bismuth 211 404.85 keV 0.0378
Bismuth 214 *609.31 keV 0.448
Bismuth 214 768.36 keV 0.048
Protactinium 234m 1001.03 keV 0.00370

Potassium 40 Hypothesis
Isotope Energy Branching Ratio
Potassium 40 *1461 keV 0.1067

Depleted Uranium Hypothesis
Isotope Energy Branching Ratio
Thorium 234 13.3 keV 0.045
Thorium 234 *63.29 keV 0.048
Thorium 234 *92.38 keV 0.028
Thorium 234 *92.8 keV 0.028
Uranium 235 19.59 keV 0.61
Uranium 235 *143.76 keV 0.1096
Uranium 235 185.71 keV 0.572
Protactinium 234m 1001.03 keV 0.00370