We are developing position-sensitive transition-edge sensor (TES) microcalorimeters (PoSTs) to detect gamma rays up to a few MeV. Each gamma-ray PoST consists of a long absorber with a TES on each end and works as a 1D imaging spectrometer. We fabricated PoSTs with 0.5 × 0.5 × 18.8 mm lead absorbers. We irradiated two PoST devices with gamma rays from a Cs-137 source. Gamma-ray pulses of the PoSTs show a strong correlation between the pulse height and the rise time. We divided the pulses in the 662 keV line into 12 groups after sorting them by rise time to determine effective pixels. We modeled the PoST device and compared the average pulses of the 12 effective pixels to numerical simulations. The actual pulses and simulated pulses were in good agreement.
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