Calibration of the deposited energy in CMOS imagers for particle detection on nanosatellite

Commercial off-the-shelf (COTS) CMOS sensors are increasingly used in scientific applications on nanosatellites. Applying a software-based approach and in addition to their image acquisitions tasks, these CMOS sensors can be used to detect ionizing particles to improve the fault tolerance of imaging instruments on nanosatellites without the need for additional hardware. A challenge in using COTS components for this approach is that essential radiation test data and important parameters such as the thickness of the sensitive epitaxial layer are typically not available. With a simplified calibration approach, we determine the epitaxial layer thickness and calibrate the deposited energy sensitivity with minimal measurement time and steps and minor requirements on the test facility. A forward model for particle track length determination with an increased angle scattering of incident protons is used to handle stronger parameter uncertainties of the test setup. It is shown that the currently used CMOS sensor (HWK1910A) is a suitable candidate for a radiation monitor, based on the determined epitaxial layer thickness and the deposited energy calibration factor, in combination with the in-orbit mission data. This enables capabilities for more individual protection measures in case of unexpected radiation environments

Time-of-flight spectroscopy of ultracold neutrons at the PSI UCN source

The ultracold neutron (UCN) source at the Paul Scherrer Institute (PSI) provides high intensities of storable neutrons for fundamental physics experiments. The neutron velocity spectrum parallel to the beamline axis was determined by time-of-flight spectroscopy using a neutron chopper. In particular, the temporal evolution of the spectrum during neutron production and UCN storage in the source storage volume was investigated and compared to Monte Carlo simulation results. A softening of the measured spectrum from a mean velocity of 7.7(1)–5.1(1) ms-1 occurred within the first 30 s after the proton beam pulse had impinged on the spallation target. A spectral hardening was observed over longer time scales of one measurement day, consistent with the effect of surface degradation of the solid deuterium moderator.ISSN:1434-6001ISSN:1434-601

Improved search for neutron to mirror-neutron oscillations in the presence of mirror magnetic fields with a dedicated spparatus at the PSI UCN source

While the international nEDM collaboration at the Paul Scherrer Institut (PSI) took data in 2017 that covered a considerable fraction of the parameter space of claimed potential signals of hypothetical neutron (n) to mirror-neutron (n′) transitions, it could not test all claimed signal regions at various mirror magnetic fields. Therefore, a new study of n−n′ oscillations using stored ultracold neutrons (UCNs) is underway at PSI, considerably expanding the reach in parameter space of mirror magnetic fields (B′) and oscillation time constants (τnn′). The new apparatus is designed to test for the anomalous loss of stored ultracold neutrons as a function of an applied magnetic field. The experiment is distinguished from its predecessors by its very large storage vessel (1.47 m3), enhancing its statistical sensitivity. In a test experiment in 2020 we have demonstrated the capabilities of our apparatus. However, the full analysis of our recent data is still pending. Based on already demonstrated performance, we will reach sensitivity to oscillation times τnn′/√ cos(β) well above a hundred seconds, with β being the angle between B′ and the applied magnetic field B. The scan of B will allow the finding or the comprehensive exclusion of potential signals reported in the analysis of previous experiments and suggested to be consistent with neutron to mirror-neutron oscillations.ISSN:2073-899

Erratum to: Data blinding for the nEDM experiment at PSI

ISSN:1434-6001ISSN:1434-601