ASIX: Single-photon, energy resolved X-ray imaging with 50 μm hexagonal hybrid pixel

The Analog Spectral Imager for X-rays is a technology demonstrator of a small-pixel Hybrid Pixel Detector (HPD) designed for applications such as X-ray diffraction, synchrotron-based material science, and soft X-ray astrophysics requiring energy-resolved imaging. The ASIX architecture aims at mitigating the adverse effects of charge sharing, typical of small-pixel devices. In contrast to other frame-based photon counters or multi-threshold devices, ASIX employs, along with a <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="m2"> <mml:mrow> <mml:mn>50</mml:mn> <mml:mtext> </mml:mtext> <mml:mi>μ</mml:mi> <mml:mtext>m</mml:mtext> </mml:mrow> </mml:math> pixel, an ultra-low-noise ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="m3"> <mml:mrow> <mml:mo>&lt;</mml:mo> </mml:mrow> </mml:math> 30 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="m4"> <mml:mrow> <mml:msup> <mml:mrow> <mml:mi>e</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> </mml:mrow> </mml:msup> </mml:mrow> </mml:math> ENC), fully analog, asynchronous, single-photon readout, targeting <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="m5"> <mml:mrow> <mml:mn>10</mml:mn> <mml:mspace width="0.3333em"/> <mml:mi>μ</mml:mi> <mml:mtext>m</mml:mtext> </mml:mrow> </mml:math> spatial resolution and 350 eV FWHM at 8 keV within the same exposure. In 2025, we began developing a small scale ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="m6"> <mml:mrow> <mml:mo>∼</mml:mo> <mml:mn>5</mml:mn> <mml:mo>×</mml:mo> <mml:mn>5</mml:mn> <mml:mtext> </mml:mtext> <mml:msup> <mml:mrow> <mml:mtext>mm</mml:mtext> </mml:mrow> <mml:mrow> <mml:mn>2</mml:mn> </mml:mrow> </mml:msup> </mml:mrow> </mml:math> ) HPD coupling a <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="m7"> <mml:mrow> <mml:mn>300</mml:mn> <mml:mtext> </mml:mtext> <mml:mi>μ</mml:mi> <mml:mtext>m</mml:mtext> </mml:mrow> </mml:math> -thick, n-on-p, edgeless silicon sensor with <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="m8"> <mml:mrow> <mml:mn>50</mml:mn> <mml:mtext> </mml:mtext> <mml:mi>μ</mml:mi> <mml:mtext>m</mml:mtext> </mml:mrow> </mml:math> pixels arranged in a hexagonal pattern to a newly designed 65-nm CMOS readout ASIC, featuring single-photon readout and on-chip analog to digital conversion, with a target rate capability of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="m9"> <mml:mrow> <mml:mn>1</mml:mn> <mml:msup> <mml:mrow> <mml:mn>0</mml:mn> </mml:mrow> <mml:mrow> <mml:mn>8</mml:mn> </mml:mrow> </mml:msup> <mml:mtext> </mml:mtext> <mml:mi>p</mml:mi> <mml:mi>h</mml:mi> <mml:mo>/</mml:mo> <mml:mi>s</mml:mi> <mml:mo>/</mml:mo> <mml:mi>c</mml:mi> <mml:msup> <mml:mrow> <mml:mi>m</mml:mi> </mml:mrow> <mml:mrow> <mml:mn>2</mml:mn> </mml:mrow> </mml:msup> </mml:mrow> </mml:math> . While the baseline for the ASIX R&amp;amp;D sensor is silicon for <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="m10"> <mml:mrow> <mml:mo>≤</mml:mo> </mml:mrow> </mml:math> 20 keV operation, the design of the readout ASIC is compatible with High-Z materials sensors, such as cadmium-telluride or gallium-arsenide, for higher energies X-rays imaging, enabling potential extension to biomedical and preclinical research. This paper describes the ASIX imager architecture and reports on the development and testing of two Minimum Viable Products (MVPs), developed by coupling XPOL-III, a readily available 180-nm CMOS readout ASIC, to a <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="m11"> <mml:mrow> <mml:mn>300</mml:mn> <mml:mtext> </mml:mtext> <mml:mi>μ</mml:mi> <mml:mtext>m</mml:mtext> </mml:mrow> </mml:math> thick silicon sensor with <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="m12"> <mml:mrow> <mml:mn>50</mml:mn> <mml:mtext> </mml:mtext> <mml:mi>μ</mml:mi> <mml:mtext>m</mml:mtext> </mml:mrow> </mml:math> pixels and to a <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="m13"> <mml:mrow> <mml:mn>750</mml:mn> <mml:mtext> </mml:mtext> <mml:mi>μ</mml:mi> <mml:mtext>m</mml:mtext> </mml:mrow> </mml:math> thick CdTe sensor with <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="m14"> <mml:mrow> <mml:mn>100</mml:mn> <mml:mtext> </mml:mtext> <mml:mi>μ</mml:mi> <mml:mtext>m</mml:mtext> </mml:mrow> </mml:math> pixels, respectively. The MVPs achieved estimated energy resolution of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="m15"> <mml:mrow> <mml:mn>780</mml:mn> <mml:mspace width="0.3333em"/> <mml:mtext>eV</mml:mtext> </mml:mrow> </mml:math> FWHM at 17.5 keV (CdTe), and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="m16"> <mml:mrow> <mml:mn>620</mml:mn> <mml:mspace width="0.3333em"/> <mml:mtext>eV</mml:mtext> </mml:mrow> </mml:math> </jats:in

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Journal
Frontiers in Sensors
Published
2025-10-30
DOI
https://doi.org/10.3389/fsens.2025.1599365
Primary Topic
Advanced X-ray and CT Imaging
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article
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article

ASIX: Single-photon, energy resolved X-ray imaging with 50 μm hexagonal hybrid pixel

M. Manghisoni, G. Magazzú, A. Brez, M.A. Subieta Vásquez et al.
Frontiers in Sensors
Advanced X-ray and CT Imaging
article

ASIX: Single-photon, energy resolved X-ray imaging with 50 μm hexagonal hybrid pixel

M. Manghisoni, G. Magazzú, A. Brez, M.A. Subieta Vásquez, Lodovico Ratti, Leonardo Orsini, Andrea Ria, Paolo Prosperi, L. Gaioni, F. Morsani, Ashish Bisht, Alberto Manfreda, L. Frontini, M. Centis Vignali, Stefano Silvestri, G. Spandre, A. Stabile, M. Pesce-Rollins, Gabriella Trucco, C. Sgrò, Paolo Bruschi, S. Ronchin, Michele Pinchera, G. Traversi, R. Beccherle, M. Minuti, O. Hammad Alì, L. Baldini, Massimo Piotto, A. Profeti, Valentino Liberali, M. Boscardin, Luca Latronico, Marco Ceccanti, Ronaldo Bellazzini, L. Palini, Danny Zanardo
article en

Abstract

The Analog Spectral Imager for X-rays is a technology demonstrator of a small-pixel Hybrid Pixel Detector (HPD) designed for applications such as X-ray diffraction, synchrotron-based material science, and soft X-ray astrophysics requiring energy-resolved imaging. The ASIX architecture aims at mitigating the adverse effects of charge sharing, typical of small-pixel devices. In contrast to other frame-based photon counters or multi-threshold devices, ASIX employs, along with a <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="m2"> <mml:mrow> <mml:mn>50</mml:mn> <mml:mtext> </mml:mtext> <mml:mi>μ</mml:mi> <mml:mtext>m</mml:mtext> </mml:mrow> </mml:math> pixel, an ultra-low-noise ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="m3"> <mml:mrow> <mml:mo>&lt;</mml:mo> </mml:mrow> </mml:math> 30 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="m4"> <mml:mrow> <mml:msup> <mml:mrow> <mml:mi>e</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> </mml:mrow> </mml:msup> </mml:mrow> </mml:math> ENC), fully analog, asynchronous, single-photon readout, targeting <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="m5"> <mml:mrow> <mml:mn>10</mml:mn> <mml:mspace width="0.3333em"/> <mml:mi>μ</mml:mi> <mml:mtext>m</mml:mtext> </mml:mrow> </mml:math> spatial resolution and 350 eV FWHM at 8 keV within the same exposure. In 2025, we began developing a small scale ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="m6"> <mml:mrow> <mml:mo>∼</mml:mo> <mml:mn>5</mml:mn> <mml:mo>×</mml:mo> <mml:mn>5</mml:mn> <mml:mtext> </mml:mtext> <mml:msup> <mml:mrow> <mml:mtext>mm</mml:mtext> </mml:mrow> <mml:mrow> <mml:mn>2</mml:mn> </mml:mrow> </mml:msup> </mml:mrow> </mml:math> ) HPD coupling a <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="m7"> <mml:mrow> <mml:mn>300</mml:mn> <mml:mtext> </mml:mtext> <mml:mi>μ</mml:mi> <mml:mtext>m</mml:mtext> </mml:mrow> </mml:math> -thick, n-on-p, edgeless silicon sensor with <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="m8"> <mml:mrow> <mml:mn>50</mml:mn> <mml:mtext> </mml:mtext> <mml:mi>μ</mml:mi> <mml:mtext>m</mml:mtext> </mml:mrow> </mml:math> pixels arranged in a hexagonal pattern to a newly designed 65-nm CMOS readout ASIC, featuring single-photon readout and on-chip analog to digital conversion, with a target rate capability of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="m9"> <mml:mrow> <mml:mn>1</mml:mn> <mml:msup> <mml:mrow> <mml:mn>0</mml:mn> </mml:mrow> <mml:mrow> <mml:mn>8</mml:mn> </mml:mrow> </mml:msup> <mml:mtext> </mml:mtext> <mml:mi>p</mml:mi> <mml:mi>h</mml:mi> <mml:mo>/</mml:mo> <mml:mi>s</mml:mi> <mml:mo>/</mml:mo> <mml:mi>c</mml:mi> <mml:msup> <mml:mrow> <mml:mi>m</mml:mi> </mml:mrow> <mml:mrow> <mml:mn>2</mml:mn> </mml:mrow> </mml:msup> </mml:mrow> </mml:math> . While the baseline for the ASIX R&amp;amp;D sensor is silicon for <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="m10"> <mml:mrow> <mml:mo>≤</mml:mo> </mml:mrow> </mml:math> 20 keV operation, the design of the readout ASIC is compatible with High-Z materials sensors, such as cadmium-telluride or gallium-arsenide, for higher energies X-rays imaging, enabling potential extension to biomedical and preclinical research. This paper describes the ASIX imager architecture and reports on the development and testing of two Minimum Viable Products (MVPs), developed by coupling XPOL-III, a readily available 180-nm CMOS readout ASIC, to a <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="m11"> <mml:mrow> <mml:mn>300</mml:mn> <mml:mtext> </mml:mtext> <mml:mi>μ</mml:mi> <mml:mtext>m</mml:mtext> </mml:mrow> </mml:math> thick silicon sensor with <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="m12"> <mml:mrow> <mml:mn>50</mml:mn> <mml:mtext> </mml:mtext> <mml:mi>μ</mml:mi> <mml:mtext>m</mml:mtext> </mml:mrow> </mml:math> pixels and to a <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="m13"> <mml:mrow> <mml:mn>750</mml:mn> <mml:mtext> </mml:mtext> <mml:mi>μ</mml:mi> <mml:mtext>m</mml:mtext> </mml:mrow> </mml:math> thick CdTe sensor with <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="m14"> <mml:mrow> <mml:mn>100</mml:mn> <mml:mtext> </mml:mtext> <mml:mi>μ</mml:mi> <mml:mtext>m</mml:mtext> </mml:mrow> </mml:math> pixels, respectively. The MVPs achieved estimated energy resolution of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="m15"> <mml:mrow> <mml:mn>780</mml:mn> <mml:mspace width="0.3333em"/> <mml:mtext>eV</mml:mtext> </mml:mrow> </mml:math> FWHM at 17.5 keV (CdTe), and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="m16"> <mml:mrow> <mml:mn>620</mml:mn> <mml:mspace width="0.3333em"/> <mml:mtext>eV</mml:mtext> </mml:mrow> </mml:math> </jats:in

Frontiers in SensorsVol. 6
University of Pisa (IT), University of Bergamo (IT), Istituto Nazionale di Fisica Nucleare (IT), University of Milan (IT), Fondazione Bruno Kessler (IT), University of Pavia (IT), Istituto Nazionale di Fisica Nucleare, Trento Institute for Fundamental Physics And Applications (IT), Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Frascati (IT)
Fondazione Bruno Kessler, Commissione Scientifica Nazionale 5, Instituto Nazionale di Fisica Nucleare
Openalex Percentile: Top 69%
Advanced X-ray and CT Imaging
DOIOpen Access PDFOpenAlex
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