Thermoluminescence (TL) and optical stimulated luminescence (OSL) emission spectra of SrSO4:Eu (0.1mol%) and CaSO4:Eu(0.1mol%) were measured. The results illuminate that the TL and OSL emission wavelengths of SrSO4:Eu are 375nm
and those of CaSO4:Eu are 385nm
Which indicate that TL and OSL have the same luminescence centers
and the luminescence comes from transitions between energy levels of Eu2+. The luminescence of Eu3 + is also observed in TL emission spectrum of CaSO4:Eu.