Low-energy Photon Detector Research Articles

The determination of pd, pt, au,ag and ir in copper by neutron activation analysis

The determination of palladium, platinum and gold in copper metal by neutron activation analysis is described. The matrix activity was separated from the noble metals by cation-exchange adsorption. Gold was extracted; palladium and platinum were precipitated. The precipitates were counted with a low-energy photon detector. The gold results were checked by instrumental neutron activation analysis. Silver, iridium, selenium, antimony and arsenic were also determined simultaneously.

Determination of uranium, antimony, indium, bromine and cobalt in atmospheric aerosols using epithermal neutron activation and a low-energy photon detector

Owing to the high ratio of resonance integral to thermal neutron activation cross-section of238U, a 5 min epithermal neutron irradiation under cadmium shielding, followed by measurement of the 74 keV photopeak of239U with a high resolution low-energy photon Ge(Li) detector, allows the fast determination of uranium in aerosols collected on a Whatman 41 cellulose filter. Uranium blanks of the cellulose filter paper require correction and limit the sensitivity. Simultaneously the concentrations of the elements cobalt, bromine, antimony and indium can be determined. In Belgium, the uranium concentrations of the aerosols were found to be constant and comparable to the uranium contents of rocks.

Instrumental neutron activation analysis for mercury in dogs administered methylmercury chloride: use of a low energy photon detector.

Mercury was determined by nondestructive neutron activation analysis in samples of brain tissue from beagles fed methylmercury chloride. The mercury concentration was not uniformly distributed throughout the central nervous system and the fastest rise in concentration occurred in components of the visual system. The analytical procedure was capable of measuring mercury instrumentally and routinely in small samples of biological materials at approximately the 0.2-ppM level within a few days after irradiation with short counting times. Comparative measurements showed that mercury determination based on /sup 197/Hg could be done With greater sensitivity by using a Ge(Li) low-energy photon detector rather than a conventional high-resolution, high-efficiency coaxial Ge(Li) detector. (auth)

Practical aspects of neutron activation determination of the platinum metals

Triple gamma coincidence counting of192Ir allowed the determination of Ir by instrumental neutron activation analysis down to 1 ppb in ultrabasic rocks and down to ca. 20 ppb in some high-furnace slags; the limiting factor for the latter matrix was the presence of124Sb. Radiochemical neutron activation analysis of the USGS standard rocks revealed that the Ir contents are up to three orders of magnitude lower than previously reported, except for the ultrabasic rocks. The factor of merit of several scintillation and semiconductor, gamma-ray detectors was determined for the neutron activation determination of Pd, Pt and Os. In the case of radiochemically pure sources, a NaI(Tl) wafer was preferred; in the presence of high-energy gamma-emitters, a Ge(Li) low-energy photon detector was superior.

Improved Isotope Tagging Detection Procedures for Synthetic Fibers Using the LEPD Detector

A new type of nuclear detector known as a low-energy photon detector (LEPD) has been developed by the nuclear industry which will enable textile firms to optimize the technique of neutron activatior analysis as applied to the tagging of synthetic textile monofilaments with rare earths and other elements. The sensitivity and resolution of the LEPD shows that, under various parameters, europium, samarium, gadolinium, terbium, dyprosium, holmium, erbium, ytterbium, lutetium, and palladium all are excellent textile tagging possibilities.

The determination of rhenium in flue dust by neutron activation analysis

Rhenium was determined by radiochemical neutron activation analysis in flue dust samples of complex chemical composition. Two separation techniques were used; distillation from perchloric-hydrochloric acid solution and hydroxide scavenging followed by extraction with tetraphenylarsonium chloride in chloroform. 186Re and 188Re were measured with a Ge(Li) low-energy photon detector. Chemical yields were determined by reactivation. For a neutron flux of 5·10 11 n cm -2 s -1, an irradiation time of 6 h and samples of ca. l g, down to 50 p.p.b. of rhenium could be determined.

Efficiency calibration of semiconductor X-ray detectors in the energy range 3–200 keV

New decay data for calibration standards are presented. Measured efficiency curves are discussed in terms of detector properties, and the level of precision attainable is considered in the context of various current applications of low energy photon detectors.

Instrumental neutron activation analysis of rocks with a low-energy photon detector

The usefulness of a small low-energy photon Ge(Li) detector for instrumental neutron activation analysis of silicate rocks was investigated. In order to avoid systematic errors caused by self-absorption of low-energy photons and by the counting geometry, a sample pelletizing technique is proposed. The spectral interferences in spectra taken with the small Ge(Li) detector and with a large one were compared and a definite advantage for a small detector was found for the determination of Ce, Nd, Sm, Eu, Gd, Tb, Dy, Tm, Yb, Lu, Ta and U.