title: Measurement of beta surface emission rate from an extended area 36Cl source using a multiwire proportional counter.
abstract: We have developed, as a national standard, a windowless multiwire proportional counting (MWPC) system for gross measurements of alpha- and beta-emitting radionuclides at an uncertainty level below 1%. Various detector characteristics have been studied and several working parameters of the system have been determined in order to achieve an optimized detection capability. The detector is commissioned through an international comparison of the beta emission rate from an extended area (36)Cl source. Correction for the dead time loss is made by the non-extendable dead time method. A linear extrapolation of pulse height spectrum is employed to correct for the loss in the detection efficiency due to discriminating against the events formed from a small number of original ion pairs. The surface emission rate was measured to be 1.84 x 10(3) counts/s with the relative combined standard uncertainty of 0.46%. The measured uncertainty indicates that the constructed MWPC is capable of serving as a national standard.
authors.affiliation: Ionizing Radiation, Korea Research Institute of Standards and Science, P.O. Box 102, Yuseong, Daejeon 305-600, Republic of Korea. lee@kriss.re.kr
authors.forename: K B
authors.initials: KB
authors.lastname: Lee
authors.forename: Jong
authors.initials: J
authors.lastname: Man Lee
authors.forename: Tae
authors.initials: T
authors.lastname: Soon Park