Temperature-dependent relative self-absorption measurements in 27Al

Nuclear resonance fluorescence measurements provide direct sensitivity to ground-state transition widths by probing the photoexcitation process of nuclear resonances. A technique in Relative Self-Absorption (RSA) measurements, in which measurements are done at multiple absorber temperatures, was developed and tested with 27Al at the Darmstadt High Intensity Photon Setup of the Superconducting Darmstadt Linear Accelerator. The advantage of this technique, over the regular RSA, is the possibility to overcome the need for theory input on the effective temperatures and the uncertainties that they introduce in the measured level widths. The technique and the preliminary results of the first test-measurements are presented in this proceedings.