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公开(公告)号：JP2001147271A
公开(公告)日：2001-05-29
申请号：JP33117799
申请日：1999-11-22
Applicant: ALOKA CO LTD
Inventor： UCHIBORI TAKESHI , MATSUBARA SHOHEI , TANIGUCHI KOJI
Abstract: PROBLEM TO BE SOLVED: To enhance detection sensitivity with respect to low-energy radiation. SOLUTION: A sample tray 30 is raised upward by a positioning mechanism 32 to bring the edge 30A of the sample tray 30 into contact with a bottom surface 22A. As a result, a first space 100 is formed as an airtight space. The first space 100 and a second space 102 are depressurized by the action of a pump 36. As air is expelled from between a sample 8 and a first scintillator 10, it is possible to enhance detection sensitivity.
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公开(公告)号：JP2001042046A
公开(公告)日：2001-02-16
申请号：JP22084999
申请日：1999-08-04
Applicant: KAWADA TSUBAME , ALOKA CO LTD
Inventor： KAWADA TSUBAME , MATSUBARA SHOHEI , OSHIMA TOSHINORI
IPC: G01T1/208
Abstract: PROBLEM TO BE SOLVED: To effectively reduce after pulses being generated immediately after a main pulse in a measuring device using a photomultiplier. SOLUTION: Photomultipliers 22 and 26 are provided with heaters 24 and 28, and are heated at a prescribed temperature (for example, 40 deg.C) by the heaters 24 and 28. A signal-processing circuit 18 reduces thermal noise by so called coincidence counting. Highly accurate measurement can be realized by the reduction of after pulses due to the heating of the photomultipliers and that of thermal noise due to coincidence counting. A cooling mechanism for cooling a light reception surface may be provided.
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公开(公告)号：JPH11311677A
公开(公告)日：1999-11-09
申请号：JP11909898
申请日：1998-04-28
Applicant: ALOKA CO LTD
Inventor： MATSUBARA SHOHEI
Abstract: PROBLEM TO BE SOLVED: To exclude the effect of N gas produced by activation during monitoring offgas taken out of reactor and existing in a large quantity and determine abnormality of fuel rod. SOLUTION: On both sides of a gas chamber 12 in which offgas is introduced, a first detector 16 and a second detector 18 are provided. For each annihilation of a positron emitted from N, two annihilation γ-rays are emitted in directions opposite to each other, which are simultaneously detected by both the first detector 16 and the second detector 18. Such a specific annihilation γ-rays are eliminated by anticoincidence count, so that the γ-rays from rare gas are measured with good sensitivity. In an operation part 54, each of species concentration is operated based on the spectrum. In a determining part 56, abnormality of fuel rod is determined and the degree of leakage is determined, based on the concentration ratio of at least two species with different half lives.
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公开(公告)号：JPH1184011A
公开(公告)日：1999-03-26
申请号：JP24438997
申请日：1997-09-09
Applicant: ALOKA CO LTD
Inventor： MATSUBARA SHOHEI
Abstract: PROBLEM TO BE SOLVED: To relieve decrease of radiation detection sensitivity in the boundary part of each radiation unit, in a body surface monitor constituted of a plurality of radiation detection units. SOLUTION: Simultaneous counters (COIN.) 20-A2 simultaneously counts the detection signals of photomultipliers 18-2 and 18-4 and outputs a detection signal corresponding to radiation which has entered a region A1 of a radiation detection unit A. Similarly, a simultaneous counter 20-B1 outputs a detection signal of a region B1 of a radiation detection unit B. A counter 32-1 between units sums up (OR operation) the outputs of the simultaneous counters 20-A2 and 20-B1. When radioactive material is positioned in the boundary part of the radiation detection units A and B, the possibility that radiation from the radioactive material enters the region A2 or the region B1 is high, so that a measurement result conformable to the radiation of the radioactive material can be obtained by using the output signal of the adder 32-1 between units.
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公开(公告)号：JPH1152061A
公开(公告)日：1999-02-26
申请号：JP21174497
申请日：1997-08-06
Applicant: ALOKA CO LTD
Inventor： MATSUBARA SHOHEI
Abstract: PROBLEM TO BE SOLVED: To provide a radioactivity measuring device avoiding work and miss of operation inputting the nuclear species of a measuring object and exactly performing radioactivity measurement. SOLUTION: A half life measuring part 26 samples the output of a ionization chamber detector 2 at least two time points and from its attenuation rate and sampling time interval, the half life T of the measuring object species is obtained. The output of a scintillation detector 10 is pulse-height-analyzed and the energy Eγ of γ-ray generated from the measuring object species is obtained. A nuclear species identifier 28 survey a half life table 40 and a radiation table 42 containing the half life and γ energy for each species and identifies species coinciding with the measured Eγ and T as measuring object species. The specified species is sent to a radioactivity quantity measuring part 24. The radioactivity quantity measuring part 24 reads out a coefficient converting to decay rate from the output of ionization chamber detector 2 depending on the nuclear species from a conversion coefficient converting to decay rate out of a conversion coefficient table 44 to obtain radioactivity quantity.
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Patent Agency Ranking
公开(公告)号：JPH09257940A
公开(公告)日：1997-10-03
申请号：JP6225896
申请日：1996-03-19
Applicant: ALOKA CO LTD
Inventor： IWAMOTO AKINORI , MATSUBARA SHOHEI , OSHIMA TOSHINORI
Abstract: PROBLEM TO BE SOLVED: To provide a radiation detector, with improved detecting limit, which can specify an incoming zone of radiation on a detecting face. SOLUTION: Four photomultiplier tubes 18-1 to 18-4 are arranged equally and symmetrically on a scintillator plate 12. Each of the photomultiplier tubes 18-1 to 18-4 is connected to pulse-height discriminators 24-1 to 24-4 through corresponding amplifiers 22-1 to 22-4, respectively. An output signal of each of the pulse-height discriminators 24-1 to 24-4 is branched to two signals, each of which is put into each of separate coincidence counters 26-1 to 26-4. Each of the coincidence counters 26-1 to 26-4 puts out an AND result of the two input signals, and each of counters 28-1 to 28-4 counts an output pulse of the corresponding coincidence counters 26-1 to 26-4, respectively. By this constitution, outputs of an adjacent pair of the photomultiplier tubes 18-1 to 18-4 are coincidence-counted, respectively. These pairs cover different zones of the scintillator plate 12, and the zone area is small. Thus, detection limit for each pair is improved, and a main incoming zone of radiation can be estimated from combinations of counting results of the pairs.
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公开(公告)号：JPH0921880A
公开(公告)日：1997-01-21
申请号：JP17320295
申请日：1995-07-10
Applicant: ALOKA CO LTD
Inventor： NAKAOKA HIROSHI , IWAMOTO AKINORI , MATSUBARA SHOHEI , OSHIMA TOSHINORI
Abstract: PROBLEM TO BE SOLVED: To accurately compute dose equivalent of βrays in a mixed field of β, γ rays by subtracting mixed γ counting value from the total counting values of βsensor, and computing only the β counting value of only βrays. SOLUTION: Both β rays and γ rays are detected with a βsensor, and only γrays are detected with γ sensors 14, 16, 18. A preamplifier 30, a discriminator 32, a counter 34 are arranged between each of sensors 12, 14, 16, 18, and a computing part 28. A count value of each sensor is inputted into the computing part 28, and a γ sensitivity table 36 for the β sensor, a βsensitivity memory 38 for the β sensor, a γ sensitivity table 40 for the γ sensor, a γ energy estimation table 42, a dose equivalent conversion factor table 44, a display 46, and a printer 48 are connected to the computing part 28. The counting value of mixed γ rays in the total counting values of the βsensor is estimated by multiplying the amount of γ rays by the γ sensitivity of the β sensor. The mixed γcounting value estimated is subtracted from the total counting values of the βsensor, and true β counting value is found. The dose amount or dose equivalent is computed with the computing part 28 from the true β counting value obtained.
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公开(公告)号：JPH07151860A
公开(公告)日：1995-06-16
申请号：JP29867293
申请日：1993-11-29
Applicant: ALOKA CO LTD
Inventor： MATSUBARA SHOHEI , YANO KENICHI
Abstract: PURPOSE:To reduce the limit of detection and to decrease the number of photomultiplier tubes in a large-area type radioactive-surface-contamination detecting apparatus using scintillation fibers. CONSTITUTION:A plurality of fiber units 12 to 18 sequentially form the right-end neighboring pairs at the right end part by every two units and sequentially form the left-end neighboring pairs at the left end by every two units so that the pairs are shifted by one unit to the right-end neighboring pairs. Photomultiplier tubes 22 and 24 are connected for every right-end neighboring pair, respectively. Photomultiplier tubes 21, 23 and 25 are connected for every left-end neighboring pair, respectively. The simultaneous counting is performed with the right and left photomultiplier tubes for the respective fiber units 12 to 18. In this constitution, the simultaneous counting for every fiber unit can be performed with approximately the same number of the photomultiplier tubes as the number of the fiber units.
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公开(公告)号：JPH0743472A
公开(公告)日：1995-02-14
申请号：JP18393093
申请日：1993-07-26
Applicant: ALOKA CO LTD
Inventor： MATSUBARA SHOHEI , OSHIMA TOSHINORI
IPC: G01T1/20
Abstract: PURPOSE:To perform the measurement of radiation accurately regardless of the amount of sample liquid. CONSTITUTION:A detecting part is constituted of two detecting parts 30 and 32, which are arranged at the upper and lower sides. The efficiency correcting value is obtained based on the fact that the ratios of the counted values of two detecting parts are different in response to the amount of sample liquid 12. The correcting value is multiplied by the total counted value of the counted values, and the true counted value is obtained. Even if the radioactive material is precipitated in the sample 12, the correction is performed in response to the intrinsic sample amount.
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公开(公告)号：JPH0627840B2
公开(公告)日：1994-04-13
申请号：JP17391391
申请日：1991-07-15
Applicant: ALOKA
Inventor： NAKAOKA HIROSHI , MATSUBARA SHOHEI , OOSHIMA TOSHINORI
IPC: G01T1/169
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