arXiv subjects

Gabriele Minervini

Publications and source records attributed to Gabriele Minervini.

25 records · Page 2Linked to original sources

arXiv2022

CUSP: a two cubesats constellation for Space Weather and solar flares X-ray polarimetry

The CUbesat Solar Polarimeter (CUSP) project aims to develop a constellation of two CubeSats orbiting the Earth to measure the linear polarisation of solar flares in the hard X-ray band by means of a Compton scattering polarimeter on board of each satellite. CUSP will allow to study the magnetic reconnection and particle acceleration in the flaring magnetic structures. CUSP is a project approved for a Phase A study by the Italian Space Agency in the framework of the Alcor program aimed to develop CubeSat technologies and missions.

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arXiv2021

Review of the particle background of the Athena X-IFU instrument

X-ray observations are limited by the background, due to intrinsic faintness or diffuse nature of the sources. The future Athena X-ray observatory has among its goals the characterization of these sources. We aim at characterizing the particle-induced background of the Athena microcalorimeter, in both its low (Soft Protons) and high (GCR) energy induced components, to assess the instrument capability to characterize background dominated sources such as the outskirts of clusters of galaxies. We compare two radiation environments, namely the L1 and L2 Lagrangian points, and derive indications against the latter. We estimate the particle-induced background level on the X-IFU microcalorimeter with Monte Carlo simulations, before and after all the solutions adopted to reduce its level. Concerning the GCR induced component the background level is compliant with the mission requirement. Regarding the Soft Protons component, the analysis does not predict dramatically different backgrounds in the L1 and L2 orbits. However, the lack of data concerning the L2 environment labels it as very weakly characterizable, and thus we advise against its choice as orbit for X-ray missions. We then use these background levels to simulate the observation of a typical galaxy cluster from its center out to 1.2 R200 to probe the characterization capabilities of the instrument out to the outskirts. We find that without any background reduction it is not possible to characterize the properties of the cluster in the outer regions. We also find no improvement of the observations when carried out during the solar maximum with respect to the solar minimum conditions.

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arXiv2019

The Demonstration Model of the ATHENA X-IFU Cryogenic AntiCoincidence Detector

The Cryogenic AntiCoincidence Detector (CryoAC) of ATHENA X-IFU is designed to reduce the particle background of the instrument and to enable the mission science goals. It is a 4 pixel silicon microcalorimeter sensed by an Ir/Au TES network. We have developed the CryoAC Demonstration Model, a prototype aimed to probe the critical technologies of the detector, i.e. the suspended absorber with an active area of 1 cm2; the low energy threshold of 20 keV; and the operation connected to a 50 mK thermal bath with a power dissipation less than 40 nW. Here we report the test performed on the first CryoAC DM sample (namely the AC-S10 prototype), showing that it is fully compliant with its requirements.

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arXiv2018

The Cryogenic AntiCoincidence detector for ATHENA X-IFU: improvement of the test setup towards the Demonstration Model

The ATHENA X-IFU development program foresees to build and characterize an instrument Demonstration Model (DM), in order to probe the system critical technologies before the mission adoption. In this respect, we are now developing the DM of the X-IFU Cryogenic Anticoincidence Detector (CryoAC), which will be delivered to the Focal Plane Assembly (FPA) development team for the integration with the TES array. Before the delivery, we will characterize and test the CryoAC DM in our CryoLab at INAF/IAPS. In this paper we report the main results of the activities performed to improve our cryogenic test setup, making it suitable for the DM integration. These activities mainly consist in the development of a mechanichal setup and a cryogenic magnetic shielding system, whose effectiveness has been assessed by FEM simulations and a measurement at warm. The preliminary performance test has been performed by means of the last CryoAC single pixel prototype, the AC-S8 pre-DM sample.

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arXiv2018

The Cryogenic AntiCoincidence detector for ATHENA X-IFU: assessing the role of the athermal phonons collectors in the AC-S8 prototype

The ATHENA X-ray Observatory is the second large-class mission in the ESA Cosmic Vision 2015-2025 science programme. One of the two on-board instruments is the X-IFU, an imaging spectrometer based on a large array of TES microcalorimeters. To reduce the particle-induced background, the spectrometer works in combination with a Cryogenic Anticoincidence detector (CryoAC), placed less than 1 mm below the TES array. The last CryoAC single-pixel prototypes, namely AC-S7 and AC-S8, are based on large area (1 cm2) Silicon absorbers sensed by 65 parallel-connected iridium TES. This design has been adopted to improve the response generated by the athermal phonons, which will be used as fast anticoincidence flag. The latter sample is featured also with a network of Aluminum fingers directly connected to the TES, designed to further improve the athermals collection efficiency. In this paper we will report the main results obtained with AC-S8, showing that the additional fingers network is able to increase the energy collected from the athermal part of the pulses (from the 6% of AC-S7 up to the 26 % with AC-S8). Furthermore, the finger design is able to prevent the quasiparticle recombination in the aluminum, assuring a fast pulse rising front (L/R limited). In our road map, the AC-S8 prototype is the last step before the development of the CryoAC Demonstration Model (DM), which will be the detector able to demonstrate the critical technologies expected in the CryoAC development programme.

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arXiv2018

The Cryogenic Anticoincidence Detector for ATHENA X-IFU: Preliminary test of AC-S9 towards the Demonstration Model

Our team is developing the Cryogenic Anticoincidence Detector (CryoAC) of the ATHENA X-ray Integral Field Unit (X-IFU). It is a 4-pixels TES-based detector, which will be placed less than 1 mm below the main TES array detector. We are now producing the CryoAC Demonstration Model (DM): a single pixel prototype able to probe the detector critical technologies, i.e. the operation at 50 mK thermal bath, the threshold energy at 20 keV and the reproducibility of the thermal conductance between the suspended absorber and the thermal bath. This detector will be integrated and tested in our cryogenic setup at INAF/IAPS, and then delivered to SRON for the integration in the X-IFU Focal Plane Assemby (FPA) DM. In this paper we report the status of the CryoAC DM development, showing the main result obtained with the last developed prototype, namely AC-S9. This is a DM-like sample, which we have preliminary integrated and tested before performing the final etching process to suspend the silicon absorber. The results are promising for the DM, since despite the limitations due to the absence of the final etching (high thermal capacity, high thermal conductance, partial TES surface coverage), we have been able to operate the detector with TB = 50 mK and to detect 6 keV photons, thus having a low energy threshold fully compatible with our requirement (20 keV).

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arXiv2017

The e-ASTROGAM mission (exploring the extreme Universe with gamma rays in the MeV-GeV range)

e-ASTROGAM (`enhanced ASTROGAM') is a breakthrough Observatory mission dedicated to the study of the non-thermal Universe in the photon energy range from 0.3 MeV to 3 GeV. The mission is based on an advanced space-proven detector technology, with unprecedented sensitivity, angular and energy resolution, combined with polarimetric capability. In the largely unexplored MeV-GeV domain, e-ASTROGAM will open a new window on the non-thermal Universe, making pioneering observations of the most powerful Galactic and extragalactic sources, elucidating the nature of their relativistic outflows and their effects on Galactic ecosystems. With a line sensitivity in the MeV energy range one to two orders of magnitude better than previous generation instruments, will determine the origin of key isotopes fundamental for the understanding of supernova explosion and the chemical evolution of our Galaxy. The mission will provide unique data of significant interest to a broad astronomical community, complementary to powerful observatories such as LIGO-Virgo-GEO600-KAGRA, SKA, ALMA, E-ELT, TMT, LSST, JWST, Athena, CTA, IceCube, KM3NeT, and the promise of eLISA. Keywords: High-energy gamma-ray astronomy, High-energy astrophysics, Nuclear Astrophysics, Compton and Pair creation telescope, Gamma-ray bursts, Active Galactic Nuclei, Jets, Outflows, Multiwavelength observations of the Universe, Counterparts of gravitational waves, Fermi, Dark Matter, Nucleosynthesis, Early Universe, Supernovae, Cosmic Rays, Cosmic antimatter.

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