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Nuclear Energy Conference & Expo (NECX)
September 8–11, 2025
Atlanta, GA|Atlanta Marriott Marquis
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Hash Hashemian: Visionary leadership
As Dr. Hashem M. “Hash” Hashemian prepares to step into his term as President of the American Nuclear Society, he is clear that he wants to make the most of this unique moment.
A groundswell in public approval of nuclear is finding a home in growing governmental support that is backed by a tailwind of technological innovation. “Now is a good time to be in nuclear,” Hashemian said, as he explained the criticality of this moment and what he hoped to accomplish as president.
L. D. Philipp, N. C. Hoitink, W. G. Spear, M. R. Wood
Nuclear Technology | Volume 20 | Number 1 | October 1973 | Pages 51-59
Technical Paper | Instrument | doi.org/10.13182/NT73-A31333
Articles are hosted by Taylor and Francis Online.
Electron drift velocity, a function of gas composition, electric field, and pressure, represents the most important design parameter for optimization of fission-counter collection time. References in the literature provide a significant source of information on drift velocities for various gases, but the information does not extend to sufficiently high electric field/pressure (E/p) ratios for use with the high-sensitivity fission counters under consideration. The data obtained for this investigation and reported here extend the drift-velocity data for argon-nitrogen mixtures to E/p regions useful for present design considerations, and at the same time compare detector performance in a high gamma field (106 R/h) with the various gas mixtures employed. Six combinations of argon-nitrogen ranging from 1 to 15% nitrogen were included in the tests. Although several other gas mixtures, such as argon-methane and argon-CO2, provide faster drift velocities, only argon-nitrogen has proven stable at the high neutron exposure levels anticipated for the Fast Flux Test Facility (1018 n/cm2). Performance comparisons show that for 800-Vdc operation the neutron counting sensitivity for Ar - 10% N2 exceeds that for Ar - 1% N2 (the fill gas most commonly used) by over a factor of 2. Corresponding collection times decreased from 160 nsec for the Ar - 1% N2 mixture to 80 nsec for the Ar - 10% N2 combination. For specific applications, it may be required to limit the voltage to <800 Vdc. The curves provide information to permit selection of the best gas mixture for a given bias voltage requirement.