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

Abstract

A ${}^{10}\mathrm{B}$-coated double-GEM neutron detector (BGEM) was developed as a ${}^3\mathrm{He}$-free cold-neutron beamline detector using a single ${\mathrm{B}}_4\mathrm{C}$ converter cathode and a 512-channel APV25 orthogonal-strip readout over an active area of $10\times 10{\mathrm{cm}}^2$. The detector was tested at the HANARO Bio-REF beamline with a monochromatic $4.5\mathring{\mathrm{A}}$ beam ($E_n=4.03\mathrm{meV}$). The absolute detection efficiency relative to a ${}^6\mathrm{Li}$-based Ce:LiCAF reference detector was ${\epsilon }_{\mathrm{BGEM}}=(8.69\pm 0.20)\%$ (stat.). The pulse-height spectrum was qualitatively consistent with Geant4 energy-deposition simulations, and Cd-mask imaging yielded a Gaussian-equivalent edge-spread width of $\sigma =555\oplus 102\mu \mathrm{m}$. These results establish a cold-neutron beamline benchmark for a single-converter BGEM detector with full-strip APV25 readout.

arXiv comment20 pages, 6 figures