Fabrication of Bismuth Absorber Arrays for NTD-Ge Hard X-ray Microcalorimeters

• Published in: Journal of low temperature physics Vol. 200; no. 5-6; pp. 336 - 341
• Main Authors: Ferruggia Bonura, S., Gulli, D., Barbera, M., Collura, A., Spoto, D., Vassallo, P., Varisco, S., Santamaria, M., Di Franco, F., Zaffora, A., Botta, L., Lo Cicero, U.
• Format: Journal Article
• Language: English
• Published: New York Springer US 01.09.2020; Springer Nature B.V
• Subjects: Absorbers; Arrays; Astrophysics; Bismuth; Calorimeters; Characterization and Evaluation of Materials; Condensed Matter Physics; Electroplating; Germanium; High temperature plasmas; Low temperature physics; Magnetic Materials; Magnetism; Physics; Physics and Astronomy; Plasma dynamics; Process parameters; Spectra; Transmutation; X ray detectors; X-rays; Bismuth electroplating; NTD-Ge microcalorimeters; Bismuth absorbers; Hard X-rays; Low-temperature detectors
• ISSN: 0022-2291; 1573-7357
• DOI: 10.1007/s10909-020-02475-6

The high-spectral-resolution detection of hard X-rays (E > 20 keV) is a challenging and nearly unexplored area in space astrophysics. Traditionally hard X-ray detectors present moderate spectral resolutions, although few tens of eV one could open new frontiers in the study of nuclear processes and high-temperature plasma dynamics in energetic processes. This can be achieved by using cryogenic microcalorimeters. Within a research activity aimed at developing arrays of neutron transmutation-doped germanium (NTD-Ge) microcalorimeters for the high-spectral-resolution detection (about 50 eV@60 keV) of hard X-rays (20 keV < E<100 keV), we developed an electroplating process to fabricate high-thickness (> 60 μm) bismuth absorber arrays. The adopted technological process and the study of related process parameters are discussed; preliminary results on produced arrays are given.