There are essentially 3 sources of natural radiation U-238, Th-232 and K-40. The counts as seen in the tea room for the top ten peaks are:
|
Nuclide |
Peak energy |
Peak Counts |
Source |
|
Ra-226 |
186 |
89345 |
2a |
|
Pb-212 |
238.6 |
262257 |
3 |
|
Pb-214 |
295.2 |
189128 |
2a |
|
Pb-214 |
351.9 |
348846 |
2a |
|
Tl-208 |
583.2 |
150161 |
3 |
|
Bi-214 |
609.3 |
407902 |
2a |
|
Ac-228 |
911.2 |
117065 |
3 |
|
Bi-214 |
1120.3 |
121232 |
2a |
|
K-40 |
1460.8 |
402854 |
1 |
|
Bi-214 |
1764,5 |
120108 |
2a |
While a bit of detail in the alpha decay chains is:
Source 1
C:/RW04B/K-40.IIS
0.0117% of natural K, 1.3 x 109 year half life
Source 2
C:/RW04B/U-238.IIS
4.5 x 109 year half life
C:/RW04B/TH-234.IIS 24 days
C:/RW04B/PA-234.IIS 6.7 hrs
Source 2a
C:/RW04B/RA-226.IIS
1600 years
Rn-222 (no photons)
Po-218 (big photon at 6002.55)
At-218 (no photons)
Rn-218 (609.31 0.124 %)
C:/RW04B/PB-214.IIS 27 minutes
C:/RW04B/BI-214.IIS 19 minutes
Po-214 (no photons)
Pb-210 22.3 years (photon at 46.52)
BI-210 5 days
Po-210 139 days (no sig photons)
Pb-206 stable
Source 2b
C:/RW04B/BI-210.IIS
3 x 106 years (also one with no gammas and 5 days)
Tl-206 (no gammas) goes to Pb-206 stable
Source 3
C:/RW04B/TH-232.IIS
1.4 x 1010 years
C:/RW04B/AC-228.IIS 6 hours
C:/RW04B/TH-228.IIS 1.9 years
C:/RW04B/RA-224.IIS 3.7 days
C:/RW04B/RN-220.IIS 55 sec
C:/RW04B/PO-216.IIS 150 msec
C:/RW04B/PB-212.IIS 10.64 hours
C:/RW04B/BI-212.IIS 1 hour
C:/RW04B/PO-212.IIS 45 sec, 298 nsec
C:/RW04B/TL-208.IIS 3 minutes
Source 4 (not usually
seen on the ground)
C:/RW04B/BE-7.IIS
53.3 days Carbon 12 hit by He-3 becomes 2 He-4 + Be-7-
This is a labelled version of Ztcase9, the background spectrum taken for 72
hours in the tea room.
The following are blow ups of varios regions
The original dos version of Robfit, corresponding to the book is in ..\robfit\reno\SROBFIT.ZIP. A unix compatible version is in ..\robfit\reno\srobunix.zip. A menu-driven version of the current robfit
is in robfit\ with directions in ..\robfit\readme.txt. 