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

Methodology for using prompt gamma activation analysis to measure the binary diffusion coefficient of a gas in a porous medium

“…A parabolic focusing element located at the end of the neutron guide tube was used to produce an equivalent thermal neutron flux at the sample location of up to 5.3 Â 10 6 cm À2 s À1 with the reactor at 950 kW [35]. The gamma detector used was a p-type ORTEC high purity germanium detector with a resolution of 1.95 at 1332 keV and a 65% relative efficiency [36] and shielded to reduce the signal from the background [37]. The analog signal generated by the detector was amplified using a Tennelec TC 702 amplifier and transformed to a digital signal by a 16 k Canberra 8713 convertor before being examined with a Multiport II Canberra multichannel analyzer.…”

“…A complete description of the system can be found in [37] and the characterization of the detection limits for argon and xenon isotopes can be found in [38], with the results summarized in Table 3.…”

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

“…A chief contributor to this variation is thought to be 135 Xe buildup in the reactor core [13]. These variations are accounted for by normalizing the counts in each PGAA measurement to the neutron counts acquired by a proportional 3 He detector located between the curved neutron guide and focusing element [11,13]. The neutron counts from the 3 He detector must also be normalized in each measurement to the HPGe detector real time during the irradiation before being directly compared to background or other comparator element measurements.…”

“…In a recent study, boron carbide thin film samples were analyzed for absolute boron concentrations using the PGAA facility at the Nuclear Engineering Teaching Laboratory (NETL) at The University of Texas at Austin. Calibration of the system was complex due to a number of factors, which include the following: large number of samples with different shapes and sizes, spatially nonuniform neutron flux profile at sample location [5,11], absence of boron solid material standards with comparable geometries and properties (absorption and scattering), and a required quick turnaround with limited expense. Furthermore, at the onset of analysis, characterization of the silicon substrates on which the boron carbide films were deposited was limited.…”

Application of the k0method in neutron activation analysis and in prompt gamma activation analysis

“…Against gamma radiation, a massive lead shielding has to be built. The most efficient shielding arrangement is when the different components (sample, beam stop, and detector) of the instrument are covered with almost closed lead chambers lined with the proper neutron shielding sheets, with the smallest possible apertures in the directions of the beam and detector [46][47][48].…”