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CN-122017932-A - Well type gamma beam monitoring detector

CN122017932ACN 122017932 ACN122017932 ACN 122017932ACN-122017932-A

Abstract

The invention discloses a well type gamma beam monitoring detector which comprises a BGO scintillation crystal with a central axial through hole, a scattering layer arranged at the incident end of the through hole, a photoelectric sensor optically coupled with the emergent end of the BGO scintillation crystal and provided with the through hole with the same specification at the center, and a fluorescent reflecting layer and a protective shell which are sequentially coated on the outer side of the BGO scintillation crystal, wherein the BGO scintillation crystal is of a cylindrical structure, and the aperture of the central axial through hole is 5-10mm. According to the well type gamma beam monitoring detector provided by the invention, the problems of signal saturation and pulse accumulation during single-pulse high-flux gamma beam measurement can be effectively avoided, the original beam energy spectrum authenticity can be kept, the detection efficiency can be simulated and calibrated, the structure is compact and easy to integrate, the beam energy spectrum reconstruction and the measurement precision can be improved by establishing a response function through Monte Carlo simulation, and the online stable real-time measurement of the beam energy spectrum and the flux can be realized.

Inventors

  • LIU LONGXIANG
  • WANG HONGWEI
  • FAN GONGTAO
  • ZHANG YUE
  • Xu Hanghua
  • HAO ZIRUI
  • DING JIAWEN

Assignees

  • 中国科学院上海高等研究院

Dates

Publication Date
20260512
Application Date
20260311

Claims (10)

  1. 1. A well-type gamma beam monitoring detector is characterized by comprising a BGO scintillation crystal with a central axial through hole, a scattering layer arranged at the incident end of the through hole, a photoelectric sensor which is optically coupled with the emergent end of the BGO scintillation crystal and is provided with the through hole with the same specification at the center, and a fluorescent reflecting layer and a protective shell which are sequentially coated on the outer side of the BGO scintillation crystal, wherein the BGO scintillation crystal is of a cylindrical structure, and the aperture of the central axial through hole is 5-10mm.
  2. 2. The well type gamma beam monitoring detector according to claim 1, wherein the BGO scintillation crystal has an outer diameter of 50-100 mm and a length of 80-150 mm, and is formed by axially splicing two sections of split type BGO scintillation crystals after end face polishing.
  3. 3. The well-type gamma beam monitoring detector according to claim 1, wherein the scattering layer is of an aluminum foil or plastic film structure, the thickness of the scattering layer is 5-50 μm, and the scattering layer is fixed at the incidence end of the through hole via a pasting manner and is used for compton scattering of incident gamma rays.
  4. 4. The well-type gamma beam monitoring detector according to claim 1, wherein the photoelectric sensor is a silicon photomultiplier, and the silicon photomultiplier is connected with the emergent end of the BGO scintillation crystal through an optical coupling agent.
  5. 5. The well-type gamma beam monitoring detector according to claim 1, wherein the fluorescent reflecting layer is made of polytetrafluoroethylene, the thickness of the fluorescent reflecting layer is more than 0.2mm, and the fluorescent reflecting layer is wrapped on the outer surface of the BGO scintillation crystal in a wrapping mode for improving light collection efficiency.
  6. 6. The well-type gamma beam monitoring detector of claim 1, further comprising a lead collimator disposed on an incident side of the detector, wherein a through hole diameter of the lead collimator is smaller than a central axial through hole aperture of the BGO scintillation crystal and larger than a gamma beam spot diameter.
  7. 7. The well gamma beam monitoring detector of claim 6, wherein the detector is adapted to operate in a vacuum environment, the operating environment having a vacuum of no more than 10 -2 Pa.
  8. 8. The well gamma beam monitoring detector of claim 7, wherein the detector is matched with a vacuum pipeline, both ends of the vacuum pipeline are sealed by aluminum or beryllium windows with the thickness not more than 0.1mm, the distance between the lead collimator and the incident end of the vacuum pipeline is not less than 60cm, and the distance between the detector and the emergent end of the vacuum pipeline is not less than 10cm.
  9. 9. The well type gamma beam monitoring detector according to claim 1, further comprising a flexible light guide, wherein the flexible light guide is of a sheet-shaped structure with a through hole in the center, the flexible light guide is attached between the outgoing end of the BGO scintillation crystal and the photoelectric sensor, optical signal conduction is achieved, the inner diameter of the protective shell is matched with the outer diameter of the BGO scintillation crystal, and the core assembly of the detector is integrally coated, so that protection and fixation are achieved.
  10. 10. The well gamma beam monitoring detector of any one of claims 1-9, further comprising a power supply and signal output assembly electrically connected to the photosensors, respectively, for providing operating voltages to the photosensors and outputting detection signals collected by the photosensors.

Description

Well type gamma beam monitoring detector Technical Field The invention relates to the technical field of nuclear detectors, in particular to a well type gamma beam monitoring detector. Background Currently, in the non-pulsed low-flux (< 10 4 Hz), high-energy (< 20 MeV) gamma ray beam flow measurement scenario, large-size scintillator detectors (such as NaI (Tl), BGO, laBr 3) and high-energy-resolution semiconductor detectors (such as HPGe) can realize reliable energy spectrum measurement under medium-low flux conditions. However, when the gamma ray beam reaches the working condition of single pulse (pulse width is less than 50 mu s) and high intensity (> 10 2 per pulse), the detector has the characteristics of high detection efficiency and long decay time, so that the problem of excessive effective detection events in unit time can occur, signal saturation, pulse accumulation and dead time effect are extremely easy to cause, and the serious distortion of the energy spectrum shape and the counting rate is finally caused. In the prior art, in order to solve the above problems, a metal absorber such as copper or lead is usually used to attenuate the incident gamma ray flux, or the count rate is reduced by reducing the crystal volume or measuring the scattered gamma by Compton scattering. However, the existing gamma beam monitoring method is difficult to meet the online monitoring requirements of high flux, real time and low interference, the original energy spectrum distribution cannot be measured, the uncertainty of gamma beam reconstruction is greatly increased, and accurate measurement of gamma beam flow is difficult to realize. Disclosure of Invention The invention aims to provide a well-type gamma beam monitoring detector, so as to solve the problems that signal saturation, pulse accumulation and dead time effects are easy to occur in single-pulse high-flux high-energy gamma beam flow measurement of a traditional scintillator and a semiconductor detector in the prior art, and the original energy spectrum distribution cannot be measured, the beam reconstruction uncertainty is increased and accurate measurement cannot be realized due to the existing count-down rate method. In order to solve the technical problems, the invention adopts the following technical scheme: The well-type gamma beam monitoring detector comprises a BGO scintillation crystal with a central axial through hole, a scattering layer arranged at the incident end of the through hole, a photoelectric sensor optically coupled with the emergent end of the BGO scintillation crystal and provided with the through hole with the same specification at the center, and a fluorescent reflecting layer and a protective shell which are sequentially coated on the outer side of the BGO scintillation crystal, wherein the BGO scintillation crystal is of a cylindrical structure, the aperture of the central axial through hole is 5-10mm, most of incident gamma ray beams directly pass through the vacuum channel when measured in a vacuum pipeline, and only a small part of incident gamma ray beams enter the BGO crystal to be detected after Compton scattering occurs in the scattering layer, so that single-pulse high-flux gamma beam real-time measurement is realized. Preferably, the BGO scintillation crystal has an outer diameter of 50-100 mm and a length of 80-150 mm, and is formed by axially splicing two sections of split type BGO scintillation crystals after end face polishing. It should be appreciated that when the length is small, the BGO scintillation crystal may also be comprised of one monolithic piece, without the need for stitching. Preferably, the scattering layer is of an aluminum foil or plastic film structure, the thickness of the scattering layer is 5-50 μm, and the scattering layer is fixed at the incidence end of the through hole channel in a pasting mode and is used for Compton scattering of incident gamma rays. Preferably, the photoelectric sensor is a silicon photomultiplier, and the silicon photomultiplier is connected with the emergent end of the BGO scintillation crystal through an optical coupling agent. Preferably, the fluorescent reflecting layer is made of polytetrafluoroethylene, the thickness of the fluorescent reflecting layer is 0.2mm or more, and the fluorescent reflecting layer is wrapped on the outer surface of the BGO scintillation crystal in a winding and wrapping mode and is used for improving light collection efficiency. Preferably, the detector also comprises a lead collimator, wherein the lead collimator is arranged on the incidence side of the detector, and the diameter of a through hole of the lead collimator is smaller than the diameter of a central axial through hole of the BGO scintillation crystal and larger than the diameter of a gamma beam spot. Preferably, the detector is integrally adapted to operate in a vacuum environment, and the vacuum degree of the operating environment is not higher than 10 -2 Pa. Preferably, the