As part of an experiment to measure the spectrum of photons emitted in beta-decay of the free neutron, we developed and operated a detector consisting of 12 bismuth germanate (BGO) crystals coupled to avalanche photodiodes (APDs). The detector was operated near liquid nitrogen temperature in the bore of a superconducting magnet and registered photons with energies from 5 keV to 1000 keV. To enlarge the detection range, we also directly detected soft X-rays with energies between 0.2 keV and 20 keV with three large area APDs. The construction and operation of the detector is presented, as well as information on operation of APDs at cryogenic temperatures.
The hyperspectral X-ray imaging has been long sought in various fields from material analysis to medical diagnosis. Here we propose a new semiconductor detector structure to realize energy-resolved imaging at potentially low cost. The working principle is based on the strong energy-dependent absorption of X-ray in solids. Namely, depending on the energy, X-ray photons experience dramatically different attenuation. An array or matrix of semiconductor cells is to map the X-ray intensity along its trajectory. The X-ray spectrum could be extracted from a Laplace like transform or even a supervised machine learning. We demonstrated an energy-resolved X-ray detection with a regular silicon camera.
The Cryogenic Underground Observatory for Rare Events (CUORE) is a ton-scale cryogenic experiment designed to search for neutrinoless double-beta decay of $^{130}$Te and other rare events. The CUORE detector consists of 988 TeO$_2$ bolometers operated underground at 10 mK in a dilution refrigerator at the Laboratori Nazionali del Gran Sasso. Candidate events are identified through a precise measurement of their energy. The absolute energy response of the detectors is established by the regular calibration of each individual bolometer using gamma sources. The close-packed configuration of the CUORE bolometer array combined with the extensive shielding surrounding the detectors requires the placement of calibration sources within the array itself. The CUORE Detector Calibration System is designed to insert radioactive sources into and remove them from the cryostat while respecting the stringent heat load, radiopurity, and operational requirements of the experiment. This paper describes the design, commissioning, and performance of this novel source calibration deployment system for ultra-low-temperature environments.
The Gravitational wave high-energy Electromagnetic Counterpart All-sky Monitor (GECAM) , composed of two small satellites, is a new mission to monitor the Gamma-Ray Bursts (GRBs) coincident with gravitational wave events with a FOV of 100% all-sky. GECAM detects and localizes 6 keV-5 MeV GRBs via 25 compact and novel Gamma-Ray Detectors (GRDs). Each GRD module is comprised of a LaBr3:Ce scintillator, SiPM array and preamplifier. A large dynamic range is achieved by the high gain and low gain channels of the preamplifier. This article discusses the performance of a GRD prototype which includes a set of radioactive sources in the range of 5.9-1332.5 keV. The energy resolution and energy to ADC channel conversion of the GRD module are also discussed. The typical energy resolution is 5.3% at 662 keV (FWHM) which meets the relevant requirements (< 8% at 662 keV). The energy calibration capability is evaluated by the measured intrinsic activity of LaBr3:Ce and Geant4 simulation results. The test results demonstrate the feasibility of the GECAM GRD design.
A prototype of a position sensitive photo-detector with 5.6 x 5.6 cm2 detection area readout with 64 Hamamatsu MPPCs (S10931-100P) with 3 x 3 mm2 active area each has been built and tested. The photo-sensors are arranged in a 8 x 8 array with a quadratic mirror light guide on top. The module is currently readout by in-house developed preamplifier boards but employing existing ASIC chips optimized for SiPM readout is also planned. Such a device is one of the candidates to be used for photon detection in the PANDA DIRC detectors.
The Argonne MCP-based photo detector is an offshoot of the Large Area Pico-second Photo Detector (LAPPD) project, wherein 6 cm x 6 cm sized detectors are made at Argonne National Laboratory. We have successfully built and tested our first detectors for pico-second timing and few mm spatial resolution. We discuss our efforts to customize these detectors to operate in a cryogenic environment. Initial plans aim to operate in liquid argon. We are also exploring ways to mitigate wave length shifting requirements and also developing bare-MCP photodetectors to operate in a gaseous cryogenic environment.