Solid deuterium surface degradation at ultracold neutron sources A. Anghel, T. L. Bailey, G. Bison, B. Blau, L. J. Broussard, S. M. Clayton, C. Cude-Woods, M. Daum, A. Hawari, N. Hild et al. (20 more) Eur. Phys. J. A, 54 9 (2018) 148 Published online: 12 September 2018 DOI: 10.1140/epja/i2018-12594-2