title: Effects of anisotropic fluences and angular depended spectra of beta-particles in the use of large area reference sources.
abstract: Calibrations of instrument efficiency of surface contamination meters are usually made with extended reference sources which are standardized in terms of 2π surface β-particle emission rates from the source surface including backscattered particles. Extended sources supplied from various metrology institutes or calibration laboratories, but the source-types such as structure, preparation method, backing and covering materials vary between manufacturers. In this work first we show how the calibration results are dependent on the source type. Second, in order to clarify the possible reason of such discrepancy, we examined the isotropy of β-particle fluences by the use of a proportional counter and also observed the angular dependence of β-particle spectra by the use of small plastic scintillation spectrometer, where the source mount can rotate relative to the detector window at various obliquities. The discrepancy in the instrument-calibration of surface contamination meters, which are mainly used under the conditions of large source-to-detector geometry, can be explained.
authors.affiliation: Japan Radioisotope Association, 2-28-45, Hon-komagome, Bunkyo, Tokyo 113-8941, Japan. tyamada@jrias.or.jp
authors.forename: Takahiro
authors.initials: T
authors.lastname: Yamada
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Kawada
authors.forename: Hidetake
authors.initials: H
authors.lastname: Ishizu
authors.forename: Shinich
authors.initials: S
authors.lastname: Yamamoto
authors.forename: Akira
authors.initials: A
authors.lastname: Yunoki
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Sato
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Unno
authors.forename: Yoshio
authors.initials: Y
authors.lastname: Hino
mesh_terms: D001610:Beta Particles; D004867:Equipment Design; D019544:Equipment Failure Analysis; D038622:Internationality; D011829:Radiation Dosage; D011874:Radiometry / Q000295:instrumentation* / Q000592:standards*; D012015:Reference Standards; D012016:Reference Values