Logo
ScienceStack
Table of Contents
Fetching ...
Sign In

Cold Neutron Imaging and Efficiency Measurements with a Boron-10 Coated Double-GEM Detector

WooJong Kim, DongHyun Kim, Minjae Kwon, Jason Sang Hun Lee, Hyupwoo Lee, Inkyu Park, Donghyun Song, Inseok Yoon, Myeonghun Choi

Abstract

A B-10 coated GEM neutron detector (BGEM) was developed as a He-3 free alternative for cold-neutron beamline instrumentation, employing a single B4C converter cathode, a double-GEM amplification stage, and an orthogonal strip readout over an active area of 10 x 10 cm^2. Performance was evaluated at the Bio-REF cold-neutron beamline of the HANARO research reactor using a monochromatic 4.5 {\angstrom} beam (En = 4.03 meV). The absolute detection efficiency, measured relative to a calibrated Li-6 based Ce:LiCAF scintillation detector, was εBGEM = 8.69 +/- 0.20 % (stat.). The spatial resolution was estimated from the edge smearing of reconstructed images of 1 mm diameter Cd-mask holes via an error-function fit to the radial edge profile, yielding approximately 700 μm. These results demonstrate stable cold-neutron operation of a single converter BGEM detector and provide a baseline for further efficiency improvements via converter and geometry optimization.

Cold Neutron Imaging and Efficiency Measurements with a Boron-10 Coated Double-GEM Detector

Abstract

A B-10 coated GEM neutron detector (BGEM) was developed as a He-3 free alternative for cold-neutron beamline instrumentation, employing a single B4C converter cathode, a double-GEM amplification stage, and an orthogonal strip readout over an active area of 10 x 10 cm^2. Performance was evaluated at the Bio-REF cold-neutron beamline of the HANARO research reactor using a monochromatic 4.5 {\angstrom} beam (En = 4.03 meV). The absolute detection efficiency, measured relative to a calibrated Li-6 based Ce:LiCAF scintillation detector, was εBGEM = 8.69 +/- 0.20 % (stat.). The spatial resolution was estimated from the edge smearing of reconstructed images of 1 mm diameter Cd-mask holes via an error-function fit to the radial edge profile, yielding approximately 700 μm. These results demonstrate stable cold-neutron operation of a single converter BGEM detector and provide a baseline for further efficiency improvements via converter and geometry optimization.
Paper Structure (11 sections, 2 equations, 4 figures, 1 table)

This paper contains 11 sections, 2 equations, 4 figures, 1 table.

Table of Contents

  1. Keywords:
  2. Introduction
  3. Detector Design and Fabrication
  4. Geometry Optimization via Geant4 Simulation
  5. Detector Fabrication
  6. Experimental Setup and Method
  7. Absolute Efficiency Measurement Setup
  8. Results
  9. Detection Efficiency
  10. Imaging and Estimation of Spatial Resolution
  11. Conclusion

Figures (4)

  • Figure 1: Photograph of the cathode foil coated with 1.5 of $^{10}\mathrm{B}_4\mathrm{C}$. The distinct reflection of the photographer's hand and camera on the surface serves as evidence of the mirror-like finish, confirming the high quality of the metallic coating and the absence of non-reflective impurities.
  • Figure 2: Measured event rates as a function of applied high voltage for both the boron-coated and uncoated detectors under beam-on and beam-off conditions. The curve labeled "Difference" represents the count rate of the coated detector minus that of the uncoated detector, illustrating the net neutron capture signal.
  • Figure 3: Pulse height spectrum measured with the BGEM detector. The simulation results corresponding to the energy deposition of $^7\text{Li}$ ions and $\alpha$ particles are overlaid as stacked filled histograms.
  • Figure 4: Cd-mask imaging used for the imaging and spatial-resolution measurement. (a) Photograph of the Cd hole mask with 1mm diameter holes; the holes inside the red box were used for the spatial-resolution analysis. (b) Zoomed view of the reconstructed 2D hit-density map corresponding to the selected area.