High energy, high resolution X-ray spectroscopy: microcalorimeters for nuclear line astrophysics

We introduce focusing optics and microcalorimeter spectroscopy to nuclear line emission astrophysics with a balloon payload concept called, B‐MINE. It is designed to probe the deepest regions of a supernova explosion by detecting 44Ti emission at 68 keV with spatial and spectral resolutions that are sufficient to determine the velocity distribution of the 44Ti emitting region. B‐MINE has a thin plastic foil telescope multilayered to maximize the reflectivity in a 20 keV band centered at 68 keV and a microcalorimeter array optimized for the same energy band. This combination provides a reduced background, an energy resolution of 50 eV and a 3σ sensitivity in 106 s of 6 × 10−8 ph cm−2 s−1 at 68 keV. During the course of a long duration balloon flight, B‐MINE could carry out a detailed study of the 44Ti emission line centroids and width in CAS A. Details of the spectrometer and simulated results are presented.