The Electron-Gamma Coincidence Setup DAGOBERT

Abstract

The QCLAM electron spectrometer at the S-DALINAC electron accelerator at Technische Universität Darmstadt has been extended by the DAGOBERT ${\hat{I}}^3$-detector array consisting of fast timing and high efficiency LaBr${}_3$:Ce detectors to perform electron-gamma coincidence measurements. The functionality of the setup and data acquisition system was demonstrated in a commissioning measurement on ${}^{12}\text{C}$ observing the $4.44$MeV and $15.11$MeV states. A medium-heavy nucleus, ${}^{96}\text{Ru}$, has been studied for the first time up to excitation energies of $15$MeV using the $(e,e^{\prime }{\hat{I}}^3)$ reaction. In particular, the angular distribution of the $2_1^{+}$ state and the ${\hat{I}}^3$-decay branching ratios of the mixed-symmetric $2_3^{+}$ state were observed. DAGOBERT@QCLAM is a new and worldwide unique setup for nuclear structure studies of excitation and decay using purely electromagnetic probes, with a significantly improved sensitivity compared to previous experiments.

36 pages, 25 figures