The NUCLEON-2 experiment is aimed at the investigation of isotope and charge composition of ions from carbon up to trans-uranium elements in the energy range over about a hundred MeV/N. The concept design of the NUCLEON-2 satellite cosmic ray experiment is presented. The performed simulation and preliminary prototype beam test confirms the isotope resolution algorithms and techniques.
The General Antiparticle Spectrometer (GAPS) will carry out a sensitive dark matter search by measuring low-energy ($mathrm{E} < 0.25 mathrm{GeV/nucleon}$) cosmic ray antinuclei. The primary targets are low-energy antideuterons produced in the annihilation or decay of dark matter. At these energies antideuterons from secondary/tertiary interactions are expected to have very low fluxes, significantly below those predicted by well-motivated, beyond the standard model theories. GAPS will also conduct low-energy antiproton and antihelium searches. Combined, these observations will provide a powerful search for dark matter and provide the best observations to date on primordial black hole evaporation on Galactic length scales. The GAPS instrument detects antinuclei using the novel exotic atom technique. It consists of a central tracker with a surrounding time-of-flight (TOF) system. The tracker is a one cubic meter volume containing 10 cm-diameter lithium-drifted silicon (Si(Li)) detectors. The TOF is a plastic scintillator system that will both trigger the Si(Li) tracker and enable better reconstruction of particle tracks. After coming to rest in the tracker, antinuclei will form an excited exotic atom. This will then de-excite via characteristic X-ray transitions before producing a pion/proton star when the antiparticle annihilates with the nucleus. This unique event topology will give GAPS the nearly background-free detection capability required for a rare-event search. Here we present the scientific motivation for the GAPS experiment, its design and its current status as it prepares for flight in the austral summer of 2021-22.
The POLARBEAR-2 CosmicMicrowave Background (CMB) experiment aims to observe B-mode polarization with high sensitivity to explore gravitational lensing of CMB and inflationary gravitational waves. POLARBEAR-2 is an upgraded experiment based on POLARBEAR-1, which had first light in January 2012. For POLARBEAR-2, we will build a receiver that has 7,588 Transition Edge Sensor (TES) bolometers coupled to two-band (95 and 150 GHz) polarization-sensitive antennas. For the large arrays readout, we employ digital frequency-domain multiplexing and multiplex 32 bolometers through a single superconducting quantum interference device (SQUID). An 8-bolometer frequency-domain multiplexing readout has been deployed on POLARBEAR-1 experiment. Extending that architecture to 32 bolometers requires an increase in the bandwidth of the SQUID electronics to 3 MHz. To achieve this increase in bandwidth, we use Digital Active Nulling (DAN) on the digital frequency multiplexing platform. In this paper, we present requirements and improvements on parasitic inductance and resistance of cryogenic wiring and capacitors used for modulating bolometers. These components are problematic above 1 MHz. We also show that our system is able to bias a bolometer in its superconducting transition at 3 MHz.
Charged Particle Monitor (CPM) on-board the AstroSat satellite is an instrument designed to detect the flux of charged particles at the satellite location. A Cesium Iodide Thallium (CsI(Tl)) crystal is used with a Kapton window to detect protons with energies greater than 1 MeV. The ground calibration of CPM was done using gamma-rays from radioactive sources and protons from particle accelerators. Based on the ground calibration results, energy deposition above 1 MeV are accepted and particle counts are recorded. It is found that CPM counts are steady and the signal for the onset and exit of South Atlantic Anomaly (SAA) region are generated in a very reliable and stable manner.
The MOSCAB experiment (Materia OSCura A Bolle) uses a new technique for Dark Matter search. The Geyser technique is applied to the construction of a prototype detector with a mass of 0.5 kg and the encouraging results are reported here; an accent is placed on a big detector of 40 kg in construction at the Milano-Bicocca University and INFN.
We have been developing monolithic active pixel sensors, X-ray Astronomy SOI pixel sensors, XRPIXs, based on a Silicon-On-Insulator (SOI) CMOS technology as soft X-ray sensors for a future Japanese mission, FORCE (Focusing On Relativistic universe and Cosmic Evolution). The mission is characterized by broadband (1-80 keV) X-ray imaging spectroscopy with high angular resolution ($<15$~arcsec), with which we can achieve about ten times higher sensitivity in comparison to the previous missions above 10~keV. Immediate readout of only those pixels hit by an X-ray is available by an event trigger output function implemented in each pixel with the time resolution higher than $10~{rm mu sec}$ (Event-Driven readout mode). It allows us to do fast timing observation and also reduces non-X-ray background dominating at a high X-ray energy band above 5--10~keV by adopting an anti-coincidence technique. In this paper, we introduce our latest results from the developments of the XRPIXs. (1) We successfully developed a 3-side buttable back-side illumination device with an imaging area size of 21.9~mm$times$13.8~mm and an pixel size of $36~{rm mu m} times 36~{rm mu m}$. The X-ray throughput with the device reaches higher than 0.57~kHz in the Event-Driven readout mode. (2) We developed a device using the double SOI structure and found that the structure improves the spectral performance in the Event-Driven readout mode by suppressing the capacitive coupling interference between the sensor and circuit layers. (3) We also developed a new device equipped with the Pinned Depleted Diode structure and confirmed that the structure reduces the dark current generated at the interface region between the sensor and the SiO$_2$ insulator layers. The device shows an energy resolution of 216~eV in FWHM at 6.4~keV in the Event-Driven readout mode.