SPOT IL - Slow positron facility in Israel

A slow positron facility is being built in Israel, at the Hebrew University, for basic and applied research. It consists of a slow positron beam and a compact Positrons Annihilation Lifetime (PAL) spectrometer. The slow positron beam follows a traditional design, using a ²²Na source, of about 40mCi, a Tungsten moderator and a unique grounded target cell, with positrons energy that can vary between 0.03 keV and 30 keV. The detection system will be comprised of High Purity Germanium and BaF₂ detectors, facing each other, for low background Doppler Broadening (DB) measurements. The target cell is designed to allow a combined measurement of sample conductivity and DB, with the flexibility to add more detection options in the future. The compact PAL spectrometer includes two fast scintillation detectors read by a fast digitizer (DRS4), with a sampling rate of 5.12 GS/s. A dedicated software package was developed to emulate analogue data acquisition. Lifetime measurements were performed using a ∼25 μCi ²²Na source. The time resolution was defined using a ⁶⁰Co source, to be 180-200ps. First positron lifetime validation measurements of Ti resulted in positrons lifetime of 157 ± 4 ps, consistent with previously published values.