Empirical formulae for mass attenuation and energy absorption coefficients from 1 keV to 20 MeV H. C. Manjunatha, L. Seenappa, K. N. Sridhar, N. Sowmya and Chikka Hanumantharayappa Eur. Phys. J. D, 71 9 (2017) 235 Published online: 12 September 2017 DOI: 10.1140/epjd/e2017-70679-7