Dr. Fabio Gastaldello Profile

Dr. Fabio Gastaldello

at INAF - IASF Milano

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Publications (6)

SPIE Journal Paper | 15 February 2022 Open Access

Mitigating the effects of particle background on the Athena Wide Field Imager

Eric Miller, Catherine Grant, Marshall Bautz, Silvano Molendi, Ralph Kraft, Paul Nulsen, Esra Bulbul, Steven Allen, David Burrows, Tanja Eraerds, Valentina Fioretti, Fabio Gastaldello, David Hall, Michael W. Hubbard, Jonathan Keelan, Norbert Meidinger, Emanuele Perinati, Arne Rau, Dan Wilkins

JATIS, Vol. 8, Issue 01, 018001, (February 2022) https://doi.org/10.1117/12.10.1117/1.JATIS.8.1.018001

KEYWORDS: Particles, Signal to noise ratio, Sensors, Camera shutters, Signal attenuation, Imaging systems, Signal detection, X-rays, Photons, X-ray imaging

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The Wide Field Imager (WFI) flying on Athena will usher in the next era of studying the hot and energetic Universe. Among Athena’s ambitious science programs are observations of faint, diffuse sources limited by statistical and systematic uncertainty in the background produced by high-energy cosmic ray particles. These particles produce easily identified “cosmic-ray tracks” along with less easily identified signals produced by secondary photons or x-rays generated by particle interactions with the instrument. Such secondaries produce identical signals to the x-rays focused by the optics and cannot be filtered without also eliminating these precious photons. As part of a larger effort to estimate the level of unrejected background and mitigate its effects, we here present results from a study of background-reduction techniques that exploit the spatial correlation between cosmic-ray particle tracks and secondary events. We use Geant4 simulations to generate a realistic particle background signal, sort this into simulated WFI frames, and process those frames in a similar way to the expected flight and ground software to produce a realistic WFI observation containing only particle background. The technique under study, self-anti-coincidence (SAC), then selectively filters regions of the detector around particle tracks, turning the WFI into its own anti-coincidence detector. We show that SAC is effective at improving the systematic uncertainty for observations of faint, diffuse sources, but at the cost of statistical uncertainty due to a reduction in signal. If sufficient pixel pulse-height information is telemetered to the ground for each frame, then this technique can be applied selectively based on the science goals, providing flexibility without affecting the data quality for other science. The results presented here are relevant for any future silicon-based pixelated x-ray imaging detector and could allow the WFI and similar instruments to probe to truly faint x-ray surface brightness.

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Proceedings Article | 23 August 2021 Poster + Paper

Design and characterization of a prototype proton response matrix for the XMM-Newton mission

V. Fioretti, T. Mineo, R. Amato, S. Lotti, C. Macculi, S. Molendi, F. Gastaldello, G. Lanzuisi, M. Cappi, M. Dadina, S. Ettori

Proceedings Volume 11822, 118221F (2021) https://doi.org/10.1117/12.2594120

KEYWORDS: X-rays, Mirrors, Optical filters, Molybdenum, Scattering, Cameras, Physics, Device simulation, Electrodes, Sensors

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Proceedings Article | 6 July 2018 Presentation + Paper

Evaluation of the ATHENA/WFI instrumental background

Andreas von Kienlin, Tanja Eraerds, Esra Bulbul, Valentine Fioretti, Fabio Gastaldello, Catherine Grant, David Hall, Andrew Holland, Jonathan Keelan, Norbert Meidinger, Silvano Molendi, Emanuele Perinati, Arne Rau

Proceedings Volume 10699, 106991I (2018) https://doi.org/10.1117/12.2311987

KEYWORDS: Particles, Sensors, Electrons, X-rays, Physics, Monte Carlo methods, Molybdenum, Aluminum, Optical filters, Cameras

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Proceedings Article | 11 July 2016 Paper

Updates on the background estimates for the X-IFU instrument onboard of the ATHENA mission

S. Lotti, C. Macculi, M. D'Andrea, L. Piro, S. Molendi, F. Gastaldello, T. Mineo, A. D'ai, A. Bulgarelli, V. Fioretti, C. Jacquey, M. Laurenza, P. Laurent

Proceedings Volume 9905, 990563 (2016) https://doi.org/10.1117/12.2232381

KEYWORDS: Particles, Monte Carlo methods, X-rays, Sensors, Mirrors, Electrons, Photons, Solar energy, Magnetism, Bismuth

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ATHENA is the second large mission in ESA Cosmic Vision 2015-2025, with a launch foreseen in 2028 towards the L2 orbit. The mission addresses the science theme “The Hot and Energetic Universe”, by coupling a high-performance X-ray Telescope with two complementary focal-plane instruments. One of these, the X-ray Integral Field Unit (X-IFU) is a TES based kilo-pixel array, providing spatially resolved high-resolution spectroscopy (2.5 eV at 6 keV) over a 5 arcmin FoV.

The background for this kind of detectors accounts for several components: the diffuse Cosmic Xray Background, the low energy particles (< ~100 keV) focalized by the mirrors and reaching the detector from inside the field of view, and the high energy particles (> ~100 MeV) crossing the spacecraft and reaching the focal plane from every direction. In particular, these high energy particles lose energy in the materials they cross, creating secondaries along their path that can induce an additional background component.

Each one of these components is under study of a team dedicated to the background issues regarding the X-IFU, with the aim to reduce their impact on the instrumental performances. This task is particularly challenging, given the lack of data on the background of X-ray detectors in L2, the uncertainties on the particle environment to be expected in such orbit, and the reliability of the models used in the Monte Carlo background computations. As a consequence, the activities addressed by the group range from the reanalysis of the data of previous missions like XMMNewton, to the characterization of the L2 environment by data analysis of the particle monitors onboard of satellites present in the Earth magnetotail, to the characterization of solar events and their occurrence, and to the validation of the physical models involved in the Monte Carlo simulations. All these activities will allow to develop a set of reliable simulations to predict, analyze and find effective solutions to reduce the particle background experienced by the X-IFU, ultimately satisfying the scientific requirement that enables the science of ATHENA.

While the activities are still ongoing, we present here some preliminary results already obtained by the group. The L2 environment characterization activities, and the analysis and validation of the physical processes involved in the Monte Carlo simulations are the core of an ESA activity named AREMBES (Athena Radiation Environment Models and Effects), for which the work presented here represents a starting point.

Proceedings Article | 26 September 2013 Paper

Status of the EPIC thin and medium filters on-board XMM-Newton after more than 10 years of operation II: analysis of in-flight data

Fabio Gastaldello, Marco Barbera, Alfonso Collura, Nicola La Palombara, Ugo Lo Cicero, Nicola Sartore, Andrea Tiengo, Salvatore Varisco

Proceedings Volume 8859, 885915 (2013) https://doi.org/10.1117/12.2030897

KEYWORDS: Stars, Visual optics, X-rays, Optical filters, Statistical analysis, Visualization, Point spread functions, Astronomical imaging, X-ray optics, Visual analytics

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Proceedings Article | 26 September 2013 Paper

Status of the EPIC thin and medium filters on-board XMM-Newton after more than 10 years of operation I: laboratory measurements on back-up filters

Marco Barbera, Simonpietro Agnello, Gianpiero Buscarino, Alfonso Collura, Fabio Gastaldello, Nicola La Palombara, Ugo Lo Cicero, Andrea Tiengo, Luisa Sciortino, Salvatore Varisco, Anna Maria Venezia

Proceedings Volume 8859, 885914 (2013) https://doi.org/10.1117/12.2030896

KEYWORDS: Aluminum, Optical filters, X-rays, Atomic force microscopy, Metals, Fermium, Frequency modulation, Silicon, Oxides, Raman spectroscopy

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