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LABR3 SCINTILLATION DETECTOR AND SPECIFIC EVENT REMOVAL METHOD

外国特許コード F160008869
整理番号 (S2015-0691-N0)
掲載日 2016年10月5日
出願国 世界知的所有権機関(WIPO)
国際出願番号 2016JP054017
国際公開番号 WO 2016136480
国際出願日 平成28年2月10日(2016.2.10)
国際公開日 平成28年9月1日(2016.9.1)
優先権データ
  • 特願2015-035788 (2015.2.25) JP
発明の名称 (英語) LABR3 SCINTILLATION DETECTOR AND SPECIFIC EVENT REMOVAL METHOD
発明の概要(英語) The present invention identifies α decay and other events included in the emission of an LaBr3 scintillator and only collects γ radiation events. An LaBr3 scintillation detector is provided with an LaBr3 scintillator 10, a photomultiplier tube 12, an oscilloscope 14, and a computer 18. The computer 18 detects the peak value Vp and the total charge amount Qtotal of a voltage waveform signal and calculates an error propagation expression function for the ratio of the peak value Vp to the total charge amount Qtotal. This error propagation expression function is used as a threshold function for identifying and removing α decay events. α decay events are identified from the peak value Vp and total charge amount Qtotal, which are measurement values that can be measured in real time.
従来技術、競合技術の概要(英語) BACKGROUND ART
In recent years, research and development in the inorganic scintillator is advanced and ever-changing, and performance is remarkably improved. Among them, LaBr3 the scintillator, as well as time resolution, good energy resolution, (662 KeV) of γ Cs-137 has features or less with respect to a line 3%. In addition, large crystals can be prepared and, by increasing Compton - peak ratio, high detection efficiency of the measurement can be expected. LaBr3 is somewhat lower effective atomic number of the scintillator, 5.3 g/cm density3 as large, suitable for measuring high-energy γ-ray, in place of the high purity Ge detector has attracted attention as a detector.
On the other hand, LaBr3 the scintillator, as self-radioactivity138 La and (1436 KeV) from the γ-ray,227 Ac series residual radioactivity (5-6 MeV of α rays) and it is, γ-ray in the measurement of a low activity, self-radioactivity is the cause of large measurement errors. In particular, with a region corresponding to the 1 .7-2.4 MeV α to disrupt the spectrum due to the presence, in high energy γ-ray region, LaBr3 of. sufficiently good characteristic of the scintillator may not be.
Fig. 12 is, LaBr3 :Cein self-radioactivity spectrum. In the figure, and the horizontal axis represents the energy (MeV), the vertical axis represents the frequency of the event. 1 .7-2.4 MeV To disrupt the α to the spectrum with many found to be present. The event that should be measured, the background of decay of α is not equal to 1 .5-2.5 MeV (BG) is thought to be a particular problem, environmental radiation or nuclear reaction and are distributed in large numbers, they are often the low modulus ratio may become a problem.
(BG) α to the disruption of background subtraction may be simply once one may think that, in the event of low modulus rate is time-consuming to obtain sufficient statistics, in addition, the detection efficiency of high energy gamma-generally a is low, in many cases be lower count rate.
The following non-patent document 1, LaBr3 signal emitted light of the scintillator and the γ-ray event α line utilizing the fact that there are differences in event, partial charge or by comparing the amount of electric charges of all the events for excluding the line α is described.
  • 出願人(英語)
  • ※2012年7月以前掲載分については米国以外のすべての指定国
  • NATIONAL UNIVERSITY CORPORATION HOKKAIDO UNIVERSITY
  • 発明者(英語)
  • ISHIKAWA MASAYORI
  • OGAWARA RYO
国際特許分類(IPC)
指定国 National States: AE AG AL AM AO AT AU AZ BA BB BG BH BN BR BW BY BZ CA CH CL CN CO CR CU CZ DE DK DM DO DZ EC EE EG ES FI GB GD GE GH GM GT HN HR HU ID IL IN IR IS JP KE KG KN KP KR KZ LA LC LK LR LS LU LY MA MD ME MG MK MN MW MX MY MZ NA NG NI NO NZ OM PA PE PG PH PL PT QA RO RS RU RW SA SC SD SE SG SK SL SM ST SV SY TH TJ TM TN TR TT TZ UA UG US UZ VC VN ZA ZM ZW
ARIPO: BW GH GM KE LR LS MW MZ NA RW SD SL SZ TZ UG ZM ZW
EAPO: AM AZ BY KG KZ RU TJ TM
EPO: AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR
OAPI: BF BJ CF CG CI CM GA GN GQ GW KM ML MR NE SN ST TD TG
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