title: The inverse-square gamma-irradiation anomaly of the Nuclear Enterprises 2575 large-volume ionisation chamber.
abstract: The Nuclear Enterprises (Model 2575) 600 cc ionisation chamber is examined to discover the cause of its anomalous behaviour in inverse-square stability measurements. Measurements and Monte Carlo calculations are employed to isolate the cause of the discrepancy. It is found that most of the effect is due to the long photon attenuation pathlengths in the long side wall of the instrument. A phenomenological procedure, based on measurements, is proposed to correct for the anomaly. The procedure results in inverse-square stability to within 0.5 % over a range of 1-7 m.
authors.affiliation: Department of Nuclear Engineering and Radiological Sciences, The University of Michigan, 2355 Bonisteel Boulevard, Ann Arbor, MI 48109, USA bielajew@umich.edu.
authors.forename: Alex F
authors.initials: AF
authors.lastname: Bielajew
authors.affiliation: Ionizing Radiation Standards, National Research Council of Canada, Ottawa, ON, Canada K1A 0R6.
authors.forename: Frédéric
authors.initials: F
authors.lastname: Tessier
authors.affiliation: Ionizing Radiation Standards, National Research Council of Canada, Ottawa, ON, Canada K1A 0R6.
authors.forename: Islam
authors.initials: I
authors.lastname: El Gamal
mesh_terms: D002138:Calibration; D003198:Computer Simulation; D005720:Gamma Rays; D006801:Humans; D008962:Models, Theoretical; D009010:Monte Carlo Method; D017785:Photons; D011874:Radiometry / Q000295:instrumentation*