title: A standard for absorbed dose rate to water in a 60Co field using a graphite calorimeter at the National Metrology Institute of Japan.
abstract: A primary standard for the absorbed dose rate to water in a ⁶⁰Co radiation field has been newly established at the National Metrology Institute of Japan. This primary standard combines the calorimetric measurements using a graphite calorimeter with the ionometric measurements using a thick-walled graphite cavity ionisation chamber. The calorimeter is operated in the constant temperature mode using AC Wheatstone bridges. The absorbed dose rate to water was determined to be 12 mGy s⁻¹ at a point of 1 m from the radiation source and at a water depth of 5 g cm⁻². The uncertainty on the calibration coefficient in terms of the absorbed dose to water of an ionisation chamber using this standard was estimated to be 0.39 % (k=1).
authors.affiliation: National Metrology Institute of Japan, AIST, Tsukuba, Ibaraki 305-8568, Japan. aist-morishita@aist.go.jp
authors.forename: Y
authors.initials: Y
authors.lastname: Morishita
authors.forename: M
authors.initials: M
authors.lastname: Kato
authors.forename: N
authors.initials: N
authors.lastname: Takata
authors.forename: T
authors.initials: T
authors.lastname: Kurosawa
authors.forename: T
authors.initials: T
authors.lastname: Tanaka
authors.forename: N
authors.initials: N
authors.lastname: Saito
mesh_terms: D002151:Calorimetry / Q000295:instrumentation* / Q000592:standards*; D003037:Cobalt Radioisotopes / Q000032:analysis* / Q000592:standards; D006108:Graphite / Q000528:radiation effects*; D007564:Japan; D011829:Radiation Dosage; D011874:Radiometry / Q000295:instrumentation* / Q000592:standards*; D012015:Reference Standards; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014867:Water / Q000737:chemistry* / Q000592:standards
chemical_list: D003037:Cobalt Radioisotopes; D014867:Water; D006108:Graphite