Depleted Argon from Old-Water Underground at Wall, South Dakota

The purpose of this project is to investigate the possibility of using underground water as a source for depleted argon which will be the target material for next generation dark matter detectors at deep underground laboratories and to design a machine that would extract argon from underground water. The only source of $^{39}$Ar from old underground water is $^{39}$Ar that is produced from (n,p) reactions with $^{39}$K. An analysis of the soil was conducted to determine the $^{39}$K content and the number of free neutrons due to ($\alpha $,n) reactions induced by $^{232}$Th and $^{238}$U decay. This was done with atomic absorption spectrometry and a low background counting facility, respectively. The results indicated that the soil contains approximately 2{\%} $^{39}$K and 2 neutrons/y/g/ppm. As a result, $^{39}$Ar is predicted to be about a factor of 70 lower than atmospheric level. In addition, a machine was designed that would be capable of extracting argon from underground water.