Research: Delayed Gamma Neutron Activation Analysis (DGNAA)

Delayed Gamma Neutron Activation Analysis can be used for measuring the composition of materials. As an example, some Silicon Controlled Rectifiers (SCRs) were irradiated, moved to a High Purity Gernamnium (HPGe) detector and then measured.

Silicon Controlled Rectifiers (SCRs) were irradiated with an Adelphi DD110.2-M neutron generator. The samples were then immediately moved to a High Purity Germanium (HPGe) detector where measurements of the gamma ray emissions were made. The graph shows the spectrum from the SCRs. A series of spectra were then taken, and the number of counts in the Technetium-99 line were measured. The SCRs contain molybdenum. When irradiated, molybdenum isotopes are made. These emit gamma rays that are observed. One of these isotopes, Molybdenum-99 decays to Technetium-99, which has a half life of 6 hours. This leads to a characteristic graph of counts as a function of time that increases to a maximum after 21 hours, and then decays away. The “grow-in” time occurs because Technetium is made from the decay of Molybdenum-99 (with a half life of 66 hours) but the Technetium itself has a different half-life of only 6 hours. Interestingly, the DGNAA technique is very sensitive and can be used to determine the quantity of the semiconductor dopants present in the SCR's silicon.

The experimental data is given in the attached Excel (.xls) file

Adelphi Technology would be happy to work with you to help you determine which neutron generator is best for your activation needs.