Radiation monitoring device

Patent metadata

Field	Value
Publication number	US-9817136-B2
Application number	US-201415315049-A
Country	US
Kind code	B2
Filing date	Jun 9, 2014
Priority date	Jun 9, 2014
Publication date	Nov 14, 2017
Grant date	Nov 14, 2017

Abstract

A radiation monitoring device includes: a scintillator emitting fluorescence upon absorption of radiation, a photo-multiplier tube converting the fluorescence into an electron pulse, a preamplifier converting the electron pulse into an analog voltage pulse, a pulse amplifier amplifying the analog voltage based on a gain control value, a dose rate measurement part measuring a dose rate based on an output of the pulse amplifier, an average half width measurement part, measuring a half width of a voltage pulse, which is among the outputs of the pulse amplifier and has a wave height larger than a preset value, and processing a predetermined number of measured data on the half widths to calculate a half width deviation, a gain control part receiving the half width deviation from the average half width measurement part, and determining the gain control value using a table, which lists relations between half widths and temperature calibration factors.

First claim

What is claimed is:

1. A radiation monitoring device comprising:
a scintillator emitting fluorescence upon absorption of radiation,
a photo multiplier tube converting the fluorescence into an electron pulse,
a preamplifier converting the electron pulse into an analog voltage pulse,
a pulse amplifier amplifying the analog voltage based on a gain control value,
a pulse counter to measure a dose rate based on an output of the pulse amplifier,
a voltage detector to measure a half width of a voltage pulse, which is among the outputs of the pulse amplifier and has a wave height larger than a preset value, and processing a predetermined number of measured data on the half widths to obtain an average half width, and further to calculate a half width deviation from the average half width and a standard value,
a controller configured to receive the half width deviation from the voltage detector, and then determine the gain control value using a table, the table listing a relation between half widths and temperature calibration factors.

2. The radiation monitoring device as set forth in claim 1 , wherein the voltage detector holds a half width data row which includes measured half widths of voltage pulses having a wave height larger than a preset value, the half widths arranged in time series, and updates the half width data row every time when the voltage detector measures a half width of a voltage pulse having a wave height larger than a preset value.

3. The radiation monitoring device as set forth in claim 2 , wherein the voltage detector obtains the half width deviation by move averaging in the use of the half width data row.

4. The radiation monitoring device as set forth in claim 3 , wherein the voltage detector judges whether a half width measured at a latest cycle is deviated from a permissible range or not, and discards the half width measured at a latest cycle when the voltage detector judges that the half width measured at the latest cycle is out of the permissible range.

5. The radiation monitoring device as set forth in claim 3 , further comprising an analyzer to analyze the output of the pulse amplifier and obtains a peak wave height position which corresponds to 1461 keV, and determining a drift compensation coefficient from the obtained peak wave height position and a reference position of a gamma ray.

6. The radiation monitoring device as set forth in claim 5 , wherein the controller receives the half width deviation from the voltage detector and then reads in a temperature calibration factor which corresponds to the received half width deviation from the table, and determines the gain control value from the temperature calibration factor which is read in and a drift compensation coefficient which is output from the analyzer.

7. The radiation monitoring device as set forth in claim 1 , wherein the voltage pulse having a wave height larger than a preset value corresponds to 1461 keV.

Assignees

• Mitsubishi Electric Corp

Inventors

• Moteki Kenichi
• Taguchi Masaki

Classifications

• G01T7/005

  calibration techniques (stabilization of spectrometer G01T1/40) · CPC title

• G01T1/2018

  Scintillation-photodiode combinations · CPC title

• G01T1/208 Primary

  Circuits specially adapted for scintillation detectors, e.g. for the photo-multiplier section · CPC title

• G01T1/40 Primary

  Stabilisation of spectrometers · CPC title

• G01T1/36

  Measuring spectral distribution of X-rays or of nuclear radiation {spectrometry (pulse selection circuits per se H03K; investigation of materials by radiation diffraction G01N23/20; spectrometer tubes H01J49/00)} · CPC title