Cf-252 FTC-CFZ-431

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Overview

An official document for the CF-252 source with serial number FTC-CFZ-431 provides a value for the neutron rate and CF-252 mass as of 03/19/1993.

The initial neutron rate and mass of cf-252 are stated to be $10^{7}s^{-1}$ and 4.2$\mu g$, respectively.

4.2 $\mu g$ would generate $9.67 \times 10^{6}$ neutrons per second. The discrepancy between these two numbers gives a 2% error.

initial source composition

CF252 used in the US is produced in batches at Oak Ridge National Laboratory which all have similar isotopic make up. I found the isotopic composition of a batch produced in 1991, two years before the production date of our source<ref> http://permalink.lanl.gov/object/tr?what=info:lanl-repo/lareport/LA-UR-12-22883 </ref>. Assuming our source has the same isotopic composition as the 1991 batch and a total mass of 4.2 $\mu$g, the values in the following table can be calculated.

Table of rates

Click here to open a table giving neutron rates and C-252 activity from dates 1/2017 to 12/2029. This calculation only includes neutrons from Cf-252, since all other daughter nuclei and possible impurities have a very low SF rate compared to Cf-252.

Formulas

Formula used for neutron rate [$s^{-1}$]:

$k=(0.5)^{\frac{(year-1993)+\frac{month-3}{12}}{2.645}}$

$n_{0}rate=9.835\times10^6\times k$

and for Cf-252 activity [$\mu Ci$]:

$activity=2283.3\times k$

References

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