Cosmo ArduSiPM: An All-in-One Scintillation-Based Particle Detector for Earth and Space Application.

Thanks to advancements in silicon photomultiplier sensors (SiPMs) and system-on-chip (SoC) technology, our INFN Roma1 group developed ArduSiPM in 2012, the first all-in-one scintillator particle detector in the literature. It used a custom Arduino Due shield to process fast signals, utilizing the Microchip Sam3X8E SoC's internal peripherals to control and acquire SiPM signals. The availability of radiation-tolerant SoCs, combined with the goal of reducing system space and weight, led to the development of an innovative second-generation board, a better-performing device called Cosmo ArduSiPM, suitable for space missions. The architecture of the new detector is based on the Microchip SAMV71 300 MHz, 32-bit ARM® Cortex®-M7 (Microchip Technology Inc., Chandler, AZ, USA). While the analog front-end is essentially identical to the ArduSiPM, it utilizes components with the smallest possible package. The board fits in a CubeSat module. Thanks to the compact design, the board has two independent channels, with a total weight of only 40 grams within a CubeSat form factor. The ArduSiPM architecture is based on a single microcontroller and fast discrete analog electronics. It benefits from the continued development of SoCs related to the IoT (Internet of Things) market. Compared with a system with a custom ASIC, this architecture based on software and SoC capabilities offers considerable advantages in terms of cost and development time. The ability to incorporate new commercial SoCs, continuously emerging from advancements in the aerospace and automotive industries, provides the system with a robust foundation for sustained growth over the years. A detailed characterization of the hardware and the system's response to different photon fluxes is presented in this article. Additionally, coupling the device with a scintillator was tested at the end of this article as a preliminary trial for future measurements, showing potential for further enhancement of the detector's capabilities.

Radiation Hardness Study of Single-Photon Avalanche Diode for Space and High Energy Physics Applications.

The radiation hardness of 180 nm complementary metal-oxide-semiconductor (CMOS) and 55 nm bipolar-CMOS-double-diffused MOS single-photon avalanche diodes (SPADs) is studied using 10 MeV and 100 MeV protons up to a displacement damage dose of 1 PeV/g. It is found that the dark count rate (DCR) levels are dependent on the number and the type of defects created. A new stepwise increase in the DCR is presented. Afterpulsing was found to be a significant contributor to the observed DCR increase. A new model for DCR increase prediction is proposed considering afterpulsing. Most of the samples under test retain reasonable DCR levels after irradiation, showing high tolerance to ionizing and displacement damage caused by protons. Following irradiation, self-healing was observed at room temperature. Furthermore, high-temperature annealing shows potential for accelerating recovery. Overall, the results show the suitability of SPADs as optical detectors for long-term space missions or as detectors for high-energy particles.

Deinococcus taklimakanensis sp. nov., isolated from desert soil.

A gamma- and UV radiation-tolerant, Gram-negative, short-rod-shaped bacterial strain, designated X-121T, was isolated from soil samples collected from the Taklimakan desert in Xinjiang, China. Strain X-121T showed the highest 16S rRNA gene sequence similarity with Deinococcus depolymerans TDMA-24T (94.7 %). Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain X-121T is a member of a novel species belonging to the clade formed by members of the genus Deinococcus in the family Deinococcaceae. The DNA G+C content of strain X-121T was 63.6 mol%. The chemotaxonomic charateristics of strain X-121T were typical of members of the genus Deinococcus, with MK-8 being the predominant respiratory quinone, summed feature 3 (16 : 1ω7c,16 : 1ω6c), 16 : 0 and 17 : 1ω8c as major cellular fatty acid, several unidentified phosphoglycolipids and glycolipids as the dominant polar lipids, galactose as the predominant cell-wall sugar and the presence of peptidoglycan with l-ornithine. Strain X-121T is therefore identified as representing a novel species, for which the name Deinococcus taklimakanensis sp. nov. is proposed, with the type strain X-121T(=CCTCC AB 207228T=KCTC 33842T).

Cancer Cells Enter an Adaptive Persistence to Survive Radiotherapy and Repopulate Tumor.

Repopulation of residual tumor cells impedes curative radiotherapy, yet the mechanism is not fully understood. It is recently appreciated that cancer cells adopt a transient persistence to survive the stress of chemo- or targeted therapy and facilitate eventual relapse. Here, it is shown that cancer cells likewise enter a "radiation-tolerant persister" (RTP) state to evade radiation pressure in vitro and in vivo. RTP cells are characterized by enlarged cell size with complex karyotype, activated type I interferon pathway and two gene patterns represented by CST3 and SNCG. RTP cells have the potential to regenerate progenies via viral budding-like division, and type I interferon-mediated antiviral signaling impaired progeny production. Depleting CST3 or SNCG does not attenuate the formation of RTP cells, but can suppress RTP cells budding with impaired tumor repopulation. Interestingly, progeny cells produced by RTP cells actively lose their aberrant chromosomal fragments and gradually recover back to a chromosomal constitution similar to their unirradiated parental cells. Collectively, this study reveals a novel mechanism of tumor repopulation, i.e., cancer cell populations employ a reversible radiation-persistence by poly- and de-polyploidization to survive radiotherapy and repopulate the tumor, providing a new therapeutic concept to improve outcome of patients receiving radiotherapy.

Carbon Nanotubes for Radiation-Tolerant Electronics.

Electronics for space applications have stringent requirements on both performance and radiation tolerance. The constant exposure to cosmic radiation damages and eventually destroys electronics, limiting the lifespan of all space-bound missions. Thus, as space missions grow increasingly ambitious in distance away from Earth, and therefore time in space, the electronics driving them must likewise grow increasingly radiation-tolerant. In this work, we show how carbon nanotube (CNT) field-effect transistors (CNFETs), a leading candidate for energy-efficient electronics, can be strategically engineered to simultaneously realize a robust radiation-tolerant technology. We demonstrate radiation-tolerant CNFETs by leveraging both extrinsic CNFET benefits owing to CNFET device geometries enabled by their low-temperature fabrication, as well as intrinsic CNFET benefits owing to CNTs' inherent material properties. By performing a comprehensive study and optimization of CNFET device geometries, we demonstrate record CNFET total ionizing dose (TID) tolerance (above 10 Mrad(Si)) and show transient upset testing on complementary metal-oxide-semiconductor (CMOS) CNFET-based 6T SRAM memories via X-ray prompt dose testing (threshold dose rate = 1.3 × 1010 rad(Si)/s). Taken together, this work demonstrates CNFETs' potential as a technology for next-generation space applications.

Resistance to Helium Bubble Formation in Amorphous SiOC/Crystalline Fe Nanocomposite.

The management of radiation defects and insoluble He atoms represent key challenges for structural materials in existing fission reactors and advanced reactor systems. To examine how crystalline/amorphous interface, together with the amorphous constituents affects radiation tolerance and He management, we studied helium bubble formation in helium ion implanted amorphous silicon oxycarbide (SiOC) and crystalline Fe composites by transmission electron microscopy (TEM). The SiOC/Fe composites were grown via magnetron sputtering with controlled length scale on a surface oxidized Si (100) substrate. These composites were subjected to 50 keV He+ implantation with ion doses chosen to produce a 5 at% peak He concentration. TEM characterization shows no sign of helium bubbles in SiOC layers nor an indication of secondary phase formation after irradiation. Compared to pure Fe films, helium bubble density in Fe layers of SiOC/Fe composite is less and it decreases as the amorphous/crystalline SiOC/Fe interface density increases. Our findings suggest that the crystalline/amorphous interface can help to mitigate helium defect generated during implantation, and therefore enhance the resistance to helium bubble formation.