Measurements were made of the spectrum of one of the collimated 60Co gamma-ray beams employed in the instrument-calibration program of the National Bureau of Standards. The high-activity calibration-source capsule was replaced by one of low activity and identical geometry. The contributions to the spectrum by the scatter from the low-activity replacement source, the housing, and the collimation system were isolated by means of supplementary measurements in free air carried out on the replacement source and on a scatter-free source. Depending on collimator setting, the scatter contribution below 1 MeV was found to be between 13 and 19 percent of the total number of photons in the beam. A description is given of the measurements and of the technique for data reduction. Detailed spectral results are presented.
In a project funded jointly by the National Bureau of Standards (NBS) and the Nuclear Regulatory Commission (NRC), NBS has developed a calibration facility for beta-particle instruments and sources used in radiationprotection dosimetry. Central to this facility are beta-particle and nearly monoenergetic electron beams characterized in terms of absorbed-dose rates to water and in terms of pulse-height distributions of beta-particle and electron spectra.This documentation utilizes material previously published or otherwise disseminated by members of the staff of the Ionizing Radiation Division of the Center for Radiation Research (CRR) of the National Bureau of Standards (NBS). After a description of the facility and the procedures, results are given of (1) studies that led to the determination of absorbed-dose rates to water for the NBS beta-particle and nearly monoenergetic electron beams, and to the uncertainties entering into these determinations; (2) studies of the influence of source configuration on beta-particle and nearly monoenergetic electron spectra; and (3) an estimate of the overall uncertainties associated with the proposed calibration service.Included also are the results of some calibrations similar to those that will be performed under the calibration service employing the beta-particle sources, and of samples of studies demonstrating the benefits of using the nearly monoenergetic electron beams in special instrument studies and in a future extension of the calibration service. i V 2 .i 40 V/mm. 8
A method was devised to measure bremsstrahl ung spectra from commercial X-ray t ubes on an a bsolute scale, using a thallium-a ctivated sodium-iodide cr ystal-scint illation spectrometer. The method was used to study bremsstrahlung spect ra between 20-and 100-kilovolt s exciting potentials from a b eryllium window tube having a t hick t ungsten t arget. Fully correct.ed, absolute experimental spectra were obtained a t exciting potentials of 50 and 100 kilovolt s.In order to compare t he experiment al results with theory , a calculation was made yield ing t he t hi ck-target bremsstrahlung spectrum derived from Sommerfeld's t h eory. Experiment a nd t heor y showed order-of-magnitude agreement. However, a char acteristic differe nce in spectral shape was observed, t he experimental spectr a showing a more prop ounced peak . This peak is near 30 kilo electron volts and gives the impression of being superimposed on the spectr al shapes expected from t heory.Finall y, a point of inter est to t he practical user of the X-radiation from beryllium windolV tubes was brought out, namely, t hat a consider able portion of the low-energy radiation , at least in t he region between 12 and 30 kilo electron volts, is str ongly absorbed in the t ungsten target. of a conventional X-ray t ube.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.