The Large Area Detector is built around an array of linear Silicon Drift Detectors read out by dedicated CMOS Application-Specific Integrated Circuits. Strict constraints on power consumption and energy resolution (200 eV FWHM at 6 keV for single-channel events, <= 240 eV FWHM overall), impose a tough trade-off. We developed a new sensor architecture to improve the performance following two strategies: firstly by confining the signal charge diffusion during drift to a single channel, and secondly by focusing this charge to a smaller anode reducing the preamplifier's noise contribution. Preliminary results show single-anode events increasing from 40% to > 94% for a best energy resolution of 219 eV FWHM at 5.9 keV at 0 degrees C.

The Enhanced X-ray Timing and Polarimetry (eXTP) mission is a flagship astronomy mission led by the Chinese Academy of Sciences (CAS) and scheduled for launch in 2029. The Large Area Detector (LAD) is one of the instruments on board eXTP and is dedicated to studying the timing of X-ray sources with unprecedented sensitivity. The development of the eXTP LAD involves a significant mass production of elements to be deployed in a significant number of countries (Italy, Austria, Germany, Poland, China, Czech Republic, France). This feature makes the Manufacturing, Assembly, Integration and Test (MAIT), Verification and Calibration the most challenging and critical tasks of the project. An optimized Flight Model (FM) implementation plan has been drawn up, aiming at a production rate of 2 Modules per week. This plan is based on the interleaving of a series of parallel elementary activities in order to make the most efficient use of time and resources and to ensure that the schedule is met.

HERMES (High Energy Rapid Modular Ensemble of Satellites) Pathfinder is a space-borne mission based on a constellation of six nano-satellites flying in a low-Earth orbit (LEO). The 3U CubeSats, to be launched in early 2025, host miniaturized instruments with a hybrid Silicon Drift Detector/GAGG:Ce scintillator photodetector system, sensitive to X-rays and gamma-rays in a large energy band. HERMES will operate in conjunction with Australian Space Industry Responsive Intelligent Thermal (SpIRIT) 6U CubeSat, launched in December 2023. HERMES will probe the temporal emission of bright high-energy transients such as Gamma-Ray Bursts (GRBs), ensuring a fast transient localization in a field of view of several steradians exploiting the triangulation technique. HERMES intrinsically modular transient monitoring experiment represents a keystone capability to complement the next generation of gravitational wave experiments. In this paper we outline the scientific case, development and programmatic status of the mission

The search for low-energy antideuterons in cosmic rays allows the addressing of fundamental physics problems testing for the presence of primordial antimatter and the nature of Dark Matter. The PHeSCAMI (Pressurized Helium Scintillating Calorimeter for AntiMatter Identification) project aims to exploit the long-living metastable states of the helium target for the identification of low-energy antideuterons in cosmic rays. A space-based pressurized helium calorimeter would provide a characteristic identification signature based on the coincident detection of a prompt scintillation signal emitted by the antideuteron energy loss during the slowing-down phase in the gas, and the (≈µs) delayed scintillation signal provided by the charged pions produced in the subsequent annihilation. The performance of a high-pressure (200-bar) helium scintillator prototype, tested in the INFN-TIFPA laboratory, will be summarized.

The High Energy Modular Array (HEMA) is one of three instruments that compose the STROBE-X mission concept. The HEMA is a large-area, high-throughput non-imaging pointed instrument based on the Large Area Detector developed as part of the LOFT mission concept. It is designed for spectral timing measurements of a broad range of sources and provides a transformative increase in sensitivity to X-rays in the energy range of 2–30 keV compared to previous instruments, with an effective area of 3.4 m^2 at 8.5 keV and an energy resolution of better than 300 eV at 6 keV in its nominal field of regard.

The Lunar Electromagnetic Monitor in X-rays (LEM-X) is a proposed observatory on the Moon surface for the detection of transients and the long-term monitoring of astrophysical sources across the whole observable sky in the 2 - 50 keV band. LEM-X is based on a compact and lightweight coded-aperture camera with a 2 sr field of view. The detector plane is composed of four individual alumina-based Detector Assemblies (DA), each one hosting a single large-area (similar to 7 x 7 cm(2)) linear Silicon Drift Detector (SDD), as well as 24 analog Application Specific Integrated Circuits (AFE ASICs), specifically developed for this project. High-voltage cables and a rigid-flex printed circuit board connect the DA to the back-end electronics and power supply. A breadboard featuring a 64-channel SDD and two AFE ASICs has been manufactured and is currently under test. The LEM-X DA is being developed within the Earth-Moon-Mars project of the Italian National Recovery and Resilience Plan.

HERMES-Pathfinder is a space-borne mission based on a constellation of six nano-satellites flying in a low-Earth orbit. The 3U CubeSats, to be launched in early 2025, host miniaturized instruments with a hybrid Silicon Drift Detector/scintillator photodetector system, sensitive to both X-rays and gamma-rays. A seventh payload unit is installed onboard SpIRIT, an Australian-Italian nano-satellite developed by a consortium led by the University of Melbourne and launched in December 2023. The project aims at demonstrating the feasibility of Gamma-Ray Burst detection and localization using miniaturized instruments onboard nano-satellites. The HERMES flight model payloads were exposed to multiple well-known radioactive sources for spectroscopic calibration under controlled laboratory conditions. The analysis of the calibration data allows both to determine the detector parameters, necessary to map instrumental units to accurate energy measurements, and to assess the performance of the instruments. We report on these efforts and quantify features such as spectroscopic resolution and energy thresholds, at different temperatures and for all payloads of the constellation. Finally we review the performance of the HERMES payload as a photon counter, and discuss the strengths and the limitations of the architecture.

Despite being a one-dimensional device by design, large-area linear Silicon Drift Detectors may exploit the diffusion of the charge cloud produced by an interacting photon to determine its two-dimensional impact position as well as its energy. Therefore, they can operate as spectral-imaging devices, which are particularly suitable for space-based X-ray coded-mask instruments, for which the trade-off between large collecting area, number of readout channels and spatial resolution is a challenge. We describe the experimental characterization of the photon reconstruction capabilities of a 169 mu m anode-pitch large-area linear Silicon Drift Detector, whose technology is the foundation of the Wide Field Monitor camera of the eXTP, STROBE-X and LEM-X space missions.

The Large Area Detector (LAD) is an instrument concept for the eXTP and STROBE-X space missions (although for the latter with a different name, HEMA). Based on linear Silicon Drift Detectors (SDD), it performs spectral-timing studies in the 2-30 keV energy range. Due to the harsh particle environment of low Earth orbit, it will be subject to radiation damage in the form of both displacement damage and Total Ionizing Dose (TID). To evaluate the response of the LAD sensor technology to TID, we exposed a prototype of a LAD detector to a Co-60 source for a total of 85 kRad. This allowed us to evaluate the contribution of TID to the end-of-life performance of the instrument.

The eXTP (enhanced X-ray Timing and Polarimetry) mission is a major project of the Chinese Academy of Sciences (CAS), with a large involvement of Europe. Its scientific payload includes four instruments: SFA (Spectroscopy Focusing Array), PFA (Polarimetry Focusing Array), LAD (Large Area Detector) and WFM (Wide Field Monitor). They offer an unprecedented simultaneous wide-band Xray timing and polarimetry sensitivity. A large European consortium is contributing to the eXTP study, both for the science and the instrumentation. Europe is expected to provide two of the four instruments: LAD and WFM; the LAD is led by Italy and the WFM by Spain. The WFM for eXTP is based on the design originally proposed for the LOFT ESA M3 mission, that underwent a Phase A feasibility study. It will be a wide field of view X-ray monitor instrument working in the 2-50 keV energy range, achieved with large-area Silicon Drift Detectors (SDDs), similar to the ones used for the LAD but with better spatial resolution. The WFM will consist of 3 pairs of coded mask cameras with a total combined field of view (FoV) of 90x180 degrees at zero response and a source localisation accuracy of similar to 1 arc min. The main goal of the WFM onboard eXTP is to provide triggers for the target of opportunity observations of the narrow field of view instruments (SFA, PFA and LAD), in order to perform the core science observation programme, dedicated to the study of matter under extreme conditions of density, gravity and magnetism. In addition, the unprecedented combination of large field of view and imaging capability, down to 2 keV, of the WFM will allow eXTP to make important discoveries of the variable and transient X-ray sky, and provide X-ray coverage of a broad range of astrophysical objects covered under 'observatory science', such as gamma-ray bursts, fast radio bursts, gravitational wave electromagnetic counterparts. In this paper we provide an overview of the WFM instrument, explaining its design, configuration, and anticipated performance. Right now, eXTP is in phase B2, after a successful I-SRR (Instrument System Requirements Review). It is waiting for the adoption of the whole eXTP mission in China. Details about the current work in Phase B2, including the manufacturing and testing of the demonstration models of the WFM subsystems, will be presented, paying also a special emphasis on the collaboration with space dedicated industrial partners.

A 7.24 x 12.03 cm2 sensor, Silicon Drift Detector (SDD), has been developed for the enhanced X-ray Timing and Polarimetry (eXTP) mission of the Chinese Academy of Science, with a large contribution by a European consortium inherited from the ESA-M3 LOFT mission study. In the frame of the project X-ray Observatories (XRO), active in the National Scientific Commission 2 of the INFN, we report the details of the qualification procedure to select from the mass production the 640 sensors that will equip the Large Area Detector (the eXTP instrument dedicated to the X-ray spectroscopy in the range 2-30 keV), with energy resolution below 240 eV FWHM at 6 keV during the entire mission duration of at least 5 years. This stringent requirement dictates the need to thoroughly verify the characteristics of each single sensor before integration in the final layout. We describe the dedicated testing facilities that have been developed. We report on the detector selection criteria and test results obtained in the pre-series production.

After the manufacture and delivery of a state-of-the-art detection system for the XRF-XAFS beamline of the synchrotron light source SESAME, a new and improved detection system was realized. This new multichannel modular detection system based on Silicon Drift Detectors consists of 8 monolithic multipixel arrays, each comprising 8 SDD cells with a total area of 570 mm2. As the previous one, this 64 channels integrated detection system includes ultra-low-noise front-end electronics, dedicated acquisition system, digital filtering, temperature control and stabilization. With respect to the SESAME version, the new instrument implements a tungsten collimation system yielding a total collimated sensitive area of 500 mm2. Optimized to work in an energy range of 3–30 keV, the system shows an overall energy resolution (sum of its 64 cells) below 180 eV FWHM at the 5.9 Mn Kα line at room temperature. We highlight the system performance and in particular the peak to background ratio, before and after the collimation of the sensors.

We describe the science case, design and expected performances of the X/Gamma-ray Imaging Spectrometer (XGIS), a GRB and transients monitor developed and studied for the THESEUS mission project, capable of covering an exceptionally wide energy band (2 keV – 10 MeV), with imaging capabilities and location accuracy <15 arcmin up to 150 keV over a Field of View of 2sr, a few hundreds eV energy resolution in the X-ray band (<30 keV) and few micro seconds time resolution over the whole energy band. Thanks to a design based on a modular approach, the XGIS can be easily re-scaled and adapted for fitting the available resources and specific scientific objectives of future high-energy astrophysics missions, and especially those aimed at fully exploiting GRBs and high-energy transients for multi-messenger astrophysics and fundamental physics.

The eXTP (enhanced x-ray timing and polarimetry) mission is a major project of the Chinese Academy of Sciences (CAS), with a large involvement of Europe. The scientific payload of eXTP includes four instruments: the SFA (spectroscopy focusing array) and the PFA (polarimetry focusing array)—led by China —the LAD (large area detector) and the WFM (wide field monitor)—led by Europe (Italy and Spain). They offer a unique simultaneous wide-band x-ray timing and polarimetry sensitivity. The WFM is a wide field x-ray monitor instrument in the 2-50 keV energy range, consisting of an array of six coded mask cameras with a field of view of 180°x90° at an angular resolution of 5 arcmin and four silicon drift detectors in each camera. Its unprecedented combination of large field of view and imaging down to 2 keV will allow eXTP to make important discoveries of the variable and transient x-ray sky and is essential in detecting transient black holes, that are part of the primary science goals of eXTP, so that they can be promptly followed up with other instruments on eXTP and elsewhere.

The Pixelated silicon Drift Detector (PixDD) is a two-dimensional multi-pixel X-ray sensor based on the technology of Silicon Drift Detectors, designed to solve the dead time and pile-up issues of photon-integrating imaging detectors. Read out by a two-dimensional self-triggering Application-Specific Integrated Circuit named RIGEL, to which the sensor is bump-bonded, it operates in the 0:5 — 15 keV energy range and is designed to achieve single-photon sensitivity and good spectroscopic capabilities even at room temperature or with mild cooling (< 150 eV resolution at 6 keV at 0 °C). The paper reports on the design and performance tests of the 128-pixel prototype of the fully integrated system.

The results of a collaborative development activity aimed to the realization of multi-cell detectors based on monolithic SDD pixel technology will be described. Two kind of detection systems, skilled for the light lines at synchrotrons, have been brought to high levels of finalization and integration; a 64 cells detection system dedicated to absorption spectroscopy (XAFS) and a 32 cells detector for the X-ray microscopy (TwinMic). The main targets of this effort, led in a tight collaboration with the beam lines scientists, were large sensitive area, high rate capabilities, state of the art efficiency and energy resolution. The aim is to reduce the beam time demand for each single measurement while delivering a cutting edge analytical power. All basic elements of those detection systems, from the detector’s design and production to the front-end and read-out electronics including the final engineering of the integrated system were customized to the specific use addressed.

We discuss the results of a proton irradiation campaign of a GAGG:Ce (Cerium-doped Gadolinium Aluminum Gallium Garnet) scintillation crystal, carried out in the framework of the HERMES-TP/SP (High Energy Rapid Modular Ensemble of Satellites - Technological and Scientific Pathfinder) mission. A scintillator sample was irradiated with 70 MeV protons, at levels equivalent to those expected in equatorial and sun-synchronous low Earth orbits over orbital periods spanning 6 months to 10 years. The data we acquired are used to introduce an original model of GAGG:Ce afterglow emission. Results from this model are applied to the HERMES-TP/SP scenario, aiming at an upper-bound estimate of the detector performance degradation resulting from afterglow emission.