A multilayer surface detector for ultracold neutrons (UCNs) is described. The top 10B layer is exposed to the vacuum chamber and directly captures UCNs. The ZnS:Ag layer beneath the 10B layer is a few microns thick, which is sufficient to detect the charged particles from the 10B(n,α)7Li neutron-capture reaction, while thin enough so that ample light due to α and 7Li escapes for detection by photomultiplier tubes. One-hundred-nm thick 10B layer gives high UCN detection efficiency, as determined by the mean UCN kinetic energy, detector materials and others. Low background, including negligible sensitivity to ambient neutrons, has also been verified through pulse-shape analysis and comparisons with other existing 3He and 10B detectors. This type of detector has been configured in different ways for UCN flux monitoring, development of UCN guides and neutron lifetime research.
@article{arxiv.1503.03424,
title = {A multilayer surface detector for ultracold neutrons},
author = {Zhehui Wang and M. A. Hoffbauer and C. L. Morris and N. B. Callahan and E. R. Adamek and J. D. Bacon and M. Blatnik and A. E. Brandt and L. J. Broussard and S. M. Clayton and C. Cude-Woods and S. Currie and E. B. Dees and X. Ding and J. Gao and F. E. Gray and K. P. Hickerson and A. T. Holley and T. M. Ito and C. -Y. Liu and M. Makela and J. C. Ramsey and R. W. Pattie, and D. J. Salvat and A. Saunders and D. W. Schmidt and R. K. Schulze and S. J. Seestrom and E. I. Sharapov and A. Sprow and Z. Tang and W. Wei and J. W. Wexler and T. L. Womack and A. R. Young and B. A. Zeck},
journal= {arXiv preprint arXiv:1503.03424},
year = {2023}
}