Patent ID: 6577697
Filing Date: 2003-06-10
Classification: G21K

Abstract:
A method of computing the atomic number density, 197n, of gold (197Au) in a sample of material, comprising the steps of:assembling a moderator assembly having a neutron source and a sample chamber; and a moderating medium surrounding the said neutron source and the said sample chamber: forming a fixed geometry of the sample; activating the sample by placing the sample in the sample chamber for a known irradiation time, thereby creating a radioactive isotope; removing the sample from the sample chamber; shielding the sample from the neutron source; placing the sample proximate a radiation detector; counting the rays emitted by the delayed decay of the radioactive isotope during a counting interval, thereby obtaining a count value, I,; and calculating the value of 197n as follows: â€‰197&it;n=I&it;â€ƒ&it;Î»&varphi;&it;â€ƒ&it;Ïƒa197&it;&varepsilon;&it;â€ƒ&it;V&it;(1-&ee;-Î»&it;â€ƒ&it;Ï„)-1&it;(&ee;-Î»&it;â€ƒ&it;Ï„&it;â€ƒ&it;1-&ee;-Î»&it;â€ƒ&it;Ï„&it;â€ƒ&it;h)-1, where &lgr; is the decay constant, &phgr; is the neutron flux in the sample chamber, 197&sgr;a is the neutron absorption cross section for 197Au, &egr; is a counting efficiency value, V is the sample volume, and &tgr; is the irradiation time from &tgr;1 to &tgr;h.