Baur, M.M.BaurClaussen, J.J.ClaussenGerth, S.S.GerthKollmer, J.J.KollmerShreve, T.T.ShreveUhlmann, N.N.UhlmannPöschel, T.T.Pöschel2022-03-062022-03-062019https://publica.fraunhofer.de/handle/publica/26735010.1016/j.powtec.2019.08.025When investigating dynamical processes in granular systems, it is frequently necessary to measure the time-resolved local material density. Recently, x-ray radiography facilities became available in many laboratories and can be used to measure the volume fraction via the attenuation of x-ray radiation along the beam direction. Naïve application of the Beer-Lambert law yields, however, unacceptably large systematic errors due to beam hardening. We present a calibration protocol which allows to reliably measure the local volume fraction based exclusively on reference measurement of known packing fraction.en621671006journal article