ASPECT-BET: A novel SDD-based detector for electron spectroscopy

Silicon Drift Detectors (SDDs) are widely used in low energy X-ray spectroscopy. However, their application in electron spectroscopy is rather recent due to the complexity of modelling the low energy interactions in silicon, which are crucial for an accurate reconstruction of the measured spectra. The ASPECT-BET Collaboration has dedicated its efforts to the development of a novel SDD-based spectrometer, with a custom design optimised for the measurement of electrons with energies in the order of hundreds of keV. This dedicated setup has been selected to ensure a wide dynamic range to accurately measure several forbidden β spectra. The novel ASPECT-BET setup implements a couple of 1 mm thick SDDs (FWHM ≈ 200 eV at 5.9 keV when cooled at −3 ◦C) with a custom readout electronics. GEANT4 simulations are used extensively to model the geometry and the spectrometer response. The spectroscopic capabilities of the setup have been tested with both X-ray and monochromatic electron sources and with a measurement of the allowed β spectrum of 14C. Currently the collaboration is focused on the first SDD-based measurement of the β spectrum associated with the 99Tc forbidden transition (Q = 297 keV).