99Tc Clause Samples

99Tc. The beta spectrum of 99Tc was measured both at PTB and at CEA, with sources prepared by different techniques, in different cryogenic setups and different detector modules, with different data acquisition systems and using different data analysis routines. At CEA, a 99Tc source was electrodeposited on a 10 µm thick gold foil. The deposit is extremely thin and should be metallic technetium. However, the deposition yield and the resulting activity per surface area were lower than expected. Therefore, a sufficiently large piece of this foil had to be folded three times to reduce its area to a size (~0.5 mm × 0.7 mm) small enough to enclose it in an MMC absorber. This source foil was then sandwiched between two gold foils (0.9 mm × 0.9 mm × 74 µm each) and this stack was diffusion welded. The final absorber has a heat capacity of 350 pJ/K at 20 mK, much larger than the previous detectors. The pulses had a rise time (10% - 90%) of 14 µs and a decay time (1/e) of 2.15 ms. Data was acquired during