Performance of the University of Texas cold-neutron prompt gamma activation analysis facility

Abstract

The University of Texas cold-neutron prompt gamma-activation analysis (PGAA) facility is operational at the 1-MW UT TRIGA research reactor. The UT-PGAA facility utilizes a guided cold neutron beam produced by the Texas Cold Neutron Source. The cold neutrons are transported to the PGAA chamber via a 6-m long curved neutron guide followed by an 80-cm long converging neutron guide. A program of testing, optimizing, and calibrating the UT-PGAA facility is currently underway. Preliminary results for the sensitivities and detection limits of boron, hydrogen, and silicon in semiconductor materials are given.

Development of boron calibration via hybrid comparator method in prompt gamma activation analysis

“…Neutron self-shielding in the sample due to boron is deemed negligible as less than 1% of the neutron flux is attenuated through the sample given the maximum film thickness, maximum possible boron concentration stated, and the boron total interaction cross-section. The PGAA facility neutron flux is sub-thermal with the faster neutron component removed due to the 6 m long, curved neutron guide [12]. For the light elements composing each sample matrix, gamma-ray self-absorption is negligible, especially as the samples are positioned at 45° with respect to the incident neutron beam and high-purity germanium (HPGe) detector face.…”

Construction and characterization of the redesigned PGAA facility at The University of Texas at Austin

“…A newly installed p-type, 65% efficient ORTEC high purity germanium (HPGe) detector with 1.95-keV resolution has replaced the original n-type, 25% efficient, 1.9-keV ORTEC HPGe detector [8]. The HPGe detector is covered with lead shielding and neutron absorbers and is used to detect the gamma rays emitted by the sample.…”

“…The new flight tube has a length of 75 cm, an entrance size of 5.0 Â 1.5 cm 2 and an exit size of 2.57 Â 0.87 cm 2 . Originally, the variation of the neutronbeam intensity was measured using a 3 He counter at the end of the focusing guide [8]. Since then, the 3 He counter has been relocated and perpendicularly positioned between the exit of the curved guide and the entrance of the new focusing guide.…”