Performance of LAPEX and its spectroscopic capabilities in the 20--300 keV energy band to observe SN1987a

Recent observations of SN1987a both in the 1–10 keV and in the 10–350 keV energy range detected X‐ray emission from the source with a very hard spectrum, a power law with α∼1.4, and a flux of ∼10 mCrab at 30 keV. We describe the performances of the LAPEX experiment for observation of SN1987a. In the 20–300 keV operative energy band of LAPEX, the following goals can be achieved: detection of emission lines due to Co57 (122 keV) and Ti44 (67.9 and 78.4 keV), elements that could be produced in the supernova explosion; measurement of the comptonized spectrum from the expanding ejecta; investigation on possible coherent pulsations due to a newly born pulsar down to timescales of ∼0.1 ms. In the following, a thorough description of the payload and of its performances will be given.