Silicon sensors are the foundational detection medium for X-rays and charged particles. While their bulk dopant distribution determines device performance, it is conventionally assumed homogeneous because traditional profiling is destructive, spatially restricted, and insensitive at the relevant concentrations. Here we introduce a non-destructive 3D doping imaging technique that turns the readout electronics of a charge-integrating hybrid pixel detector into a massively parallelized capacitance-voltage profiler. With a few tens of micrometres of 3D resolution over wafer-scale areas at concentrations on the order of 10^11 cm^-3, we image the bulk doping concentration of operational sensors. Macroscopically, we resolve depth-evolving concentric doping rings; microscopically, we uncover scattered doping anomalies that distort local electric fields. The rings modulate the depletion voltage, while the anomalies disrupt local charge collection, a previously overlooked cause of pixel yield and performance degradation. By bridging manufacturing signatures with microscopic defects, this approach provides a non-destructive framework for sensor characterization and yield optimization.

A Jungfrau-1M detector has undergone testing at Diamond Light Source. The Jungfrau series of detectors from PSI use integration and adaptive gain, to offer very high frame rate and dynamic range, suitable for high-flux and time-resolved measurements. They are becoming more widely used, to take advantage of increasing light source brightness. We report on our experiences in testing the performance of a Jungfrau-1M without illumination, with a laboratory X-ray tube and on a microfocus beamline. The Jungfrau-1M was found to be able to resolve single photons in the laboratory and on the beamline. It was confirmed that range switching from high to intermediate gain is associated with a discontinuity in the detector response. Two methods of dark frame subtraction were compared for their effect on minimizing this discontinuity. The Jungfrau-1M was found to be very effective for recording macromolecular crystallography diffraction patterns, with no apparent detriment from the discontinuity. The Diamond machine will be upgraded in 2028-9 and will operate at significantly higher flux than at present, necessitating increased use of integrating detectors, such as Jungfrau, in the future.

JUNGFRAU is a state-of-the-art charge-integrating X-ray detector widely used for imaging, diffraction and spectroscopy experiments at synchrotrons and free electron lasers. The current frame rate is 2.2 kHz, limited by analog signal integrity due to the number of available output pads. With the goal of increasing the frame rate of the detector to over 10 kHz, we have designed a digital 3.125 Gbps high-speed serial readout. Consequently, the development of a fast Analog-To-Digital Converter ADC has become our primary goal to overcome the aforementioned constraints. In addition, on-chip digitization reduces noise pickup and signal distortion caused by wirebonds,traces, and other off-chip components. The ADC has been submitted in June 2024 and arrived at PSI for testing in October 2024. This contribution presents the first characterization results of the new ADC prototype, using standard ADC characterization techniques including statistical histogram testing.

With the evolution of synchrotron light sources to fourth generation (diffraction-limited storage rings), the brilliance is increased by several orders of magnitude compared to third generation facilities. For example, the Swiss Light Source (SLS) has been upgraded to SLS 2.0, promising a horizontal emittance reduced by a factor of 40, and a brilliance up to two orders of magnitude (three at higher energies). A key challenge arising from the increased flux is the heightened accumulated dose in silicon sensors, which leads to a significant increase in radiation damage. This translates into an increase of both noise and dark current, as well as a reduction in the dynamic range for long exposure times, thus affecting the performance of the detector, in particular, for charge-integrating detectors. We have designed sensors with a 4 × 4 mm2 pixel array featuring 16 design variations of 25 µm pitch pixels with different implant and metal sizes and tested them bump-bonded to MÖNCH 0.3, a charge integrating hybrid pixel detector readout ASIC. Following a first assessment of the functionality and performance of the different pixel designs, the assembly has been irradiated with X-rays. The variation in the tested parameters was characterized at different accumulated doses up to 100 kGy at the sensor entrance window side. The annealing dynamics at room temperature have also been measured. The results show that the default pixel design is currently not optimal and can benefit from layout changes (reduction in the inter-pixel gap area with full metal coverage of the implant). Further studies on the metal coverage over large implants could be conducted. The layout changes are, however, not sufficient for future full-sized sensors, requiring improved radiation hardness and long-term stability, and additional strategies such as focusing on detector cooling and changes in sensor technologies would be required.

Resonant inelastic X-ray scattering (RIXS) is a powerful photon-in, photon-out spectroscopy technique for probing electronic, magnetic, and lattice excitations in matter. Time-resolved RIXS extends this capability through a stroboscopic optical pump-probe scheme to characterize the time evolution of the photoexcitation and subsequent relaxation dynamics of a sample. This technique is, however, extremely photon-hungry, requiring high-repetition-rate and intense X-ray facilities. The Heisenberg RIXS (hRIXS) spectrometer at the Spectroscopy and Coherent Scattering (SCS) instrument of the European X-ray Free-Electron Laser (EuXFEL) is designed to exploit high-repetition-rates, while maintaining optimal time and energy resolution. In this work, we demonstrate the successful deployment of a JUNGFRAU detector equipped with an inverse Low Gain Avalanche Diode (iLGAD) sensor for time-resolved RIXS studies in the soft X-ray range, using the hRIXS spectrometer. A spatial resolution of 19.71 ± 0.7 μm and a resolving power exceeding 10,000 were achieved at an unprecedented frame rate of 47 kHz. Intra-train resolved data measured with a high FEL peak fluence of 1.8 mJ/cm^2 for a 928.5 eV ph photon energy and 1.1 MHz repetition rate from cupric oxide (CuO) revealed a decrease in the emitted signal by 10

Abstract Gotthard-II is a charge-integrating silicon microstrip detector developed for energy-dispersive experiments and X-ray photon beam diagnostics at the European X-ray Free-Electron Laser (EuXFEL). Its one-dimensional geometry, featuring fewer readout channels than pixel detectors, and its fast readout capability make it the only segmented detector able to perform experiments at a 4.5 MHz frame rate while capturing all 2700 X-ray pulses in a bunch train produced by the EuXFEL machine. The Gotthard-II detector was tested for single-photon sensitivity and dynamic range, meeting all specifications. In addition to FEL applications operating at a 4.5 MHz frame rate in burst mode, the detector supports continuous acquisition at up to 400 kHz and counting mode at ≤4.5 MHz for synchrotron applications. Experimental tests with standard samples using X-ray diffraction and X-ray emission spectroscopy were conducted at several beamlines of the Swiss Light Source (SLS) and EuXFEL. The measurement results were compared with those obtained using established detectors at these beamlines, demonstrating the performance of the detector in energy-dispersive experiments.

The single photon counting microstrip detector MYTHEN III was developed at the Paul Scherrer Institute to satisfy the increasing demands in detector performance of synchrotron radiation experiments, focusing on time-resolved and on-edge powder diffraction measurements. Similar to MYTHEN II, the detector installed on the Material Science beamline covers 120° in 2θ. It is based on the MYTHEN III.0 readout chip wire-bonded to silicon strip sensors with a pitch of 50 µm, and it provides improved performance and features with respect to the previous version. Taking advantage of the three independent comparators of MYTHEN III, it is possible to obtain an improvement in the maximum count rate capability of the detector at 90% efficiency from 2.9 ± 0.8 Mphotons s−1 strip−1 to 11 ± 2 Mphotons s−1 strip−1 thanks to the detection of pile-up at high photon flux. The readout chip offers additional operation modes such as pump–probe and digital on-chip interpolation. The maximum frame rate is up to 360 kHz in 8-bit mode with dead-time-free readout. The minimum detectable energy of MYTHEN III is 4.3 ± 0.3 keV with a minimum equivalent noise charge (ENC) of 121 ± 8 electrons and a threshold dispersion below 33 ± 10 eV. The energy calibration is affected by temperature by less than 0.5% °C−1. This paper presents a comprehensive overview of the MYTHEN III detector system with performance benchmarks, and highlights the improvements reached in powder diffraction experiments compared with the previous detector generation.

High-Z compound semiconductors aim to replace silicon as sensor material for X-ray energies above 15 keV thanks to their superior absorption efficiency. However, compared to silicon, high-Z sensors still lack in several aspects such as homogeneity, charge transport properties, charge trapping (leading to polarization and afterglow effects), long ranged fluorescence photons, and others.The aim of this study is to identify sensor materials that can widen the usable energy range of our detector systems at synchrotron sources and free electron lasers (FELs) towards higher photon energies. The main characterization tool was the 75 μm pitch JUNGFRAU charge integrating detector in combination with various high-Z sensors. As charge integrating detectors allow the direct measurement of the collected charge of every single photon with a high spatial resolution, these detectors offer interesting insights into temporal as well as spatial sensor effects which affect the charge collection.As one of the major challenges of the upcoming 4 th generation of synchrotrons or FELs are very intense and potentially pulsed photon beams, the sensors needs to be able to reliably measure highly intense signals and to have no afterglow phenomena after illumination. Measurements performed at the Material Science (MS) beamline of the SLS using photon fluxes up to 5×10 10 ph/(mm 2 • s) and at the FXE beamline of the EuXFEL focused on understanding the dynamic behavior (like signal stability, polarization and afterglow effects) of various high-Z sensor materials like GaAs:Cr (from different suppliers), as well as CdTe (Ohmic and Schottky type) and CdZnTe.The presentation will give an overview of the specific needs of the sensors for the different photon sources and will show how the results obtained fulfill these requirements.

JUNGFRAU is a state-of-the-art charge-integrating detector for high performance experiments at synchrotrons and free-electron lasers. It is currently limited to a frame rate of 2.2 kHz. With the goal to increase the frame rate of the detector to $\gt10 \mathrm{kHz}$, we have designed a 3.125 Gbps high speed serial readout. Thus, the development of a fast Analog-To-Digital Converter (ADC) has become a priority. The design of the current rail-to-rail, fully differential ADC prototype will be presented along simulation results and laboratory evaluation. The prototype targets a sampling rate of $20 \mathrm{MS} / \mathrm{s}$ together with an effective number of bits (ENOB) of equal to or greater than 11 bits. Power and area requirements to reach this goal are currently under evaluation. To meet these demands, a 12-bit Successive Approximation Register (SAR) ADC has been developed and fabricated in the 110 nm UMC CMOS process. We present laboratory characterization results, verifying the design requirements together with a comparison to other ADCs targeting similar use cases.

Water can be dynamically over-compressed well into the stability field of ice VII. Whether water then transforms into ice VII, vitreous ice or a metastable novel crystalline phase remained uncertain. We report here the freezing of over-compressed water to ice VII by time-resolved X-ray diffraction. Quasi-isothermal dynamic compression paths are achieved using a dynamic-piezo-Diamond-Anvil-Cell, with programmable pressure rise time from 0.1 ms to 100 ms. By combining the present data set with those obtained on various ns-dynamical platforms, a complete evolution of the solidification pressure of metastable water versus the compression rate is rationalized within the classical nucleation theory framework. Also, when crystallization into ice VII occurs in between 1.6 GPa and 2.0 GPa, that is in the stability field of ice VI, a structural evolution over few ms is then observed into a mixture of ice VI and ice VII that seems to resolve apparent contradictions between previous results. Metastable water, when dynamically over-compressed, freezes into ice VII. Here the authors present a dynamic diamond anvil cell (d-DAC) study that unifies data acquired across multiple platforms, explaining the solidification pressure evolution under varying compression rates using classical nucleation theory.

Hybrid pixel detectors have become indispensable at synchrotron and X-ray free-electron laser facilities thanks to their large dynamic range, high frame rate, low noise, and large area. However, at energies below 3 keV, the detector performance is often limited because of the poor quantum efficiency of the sensor and the difficulty in achieving single-photon resolution due to the low signal-to-noise ratio. In this paper, we address the quantum efficiency of silicon sensors by refining the design of the entrance window, mainly by passivating the silicon surface and optimizing the dopant profile of the n+ region. We present the measurement of the quantum efficiency in the soft X-ray energy range for silicon sensors with several process variations in the fabrication of planar sensors with thin entrance windows. The quantum efficiency for 250 eV photons is increased from almost 0.5% for a standard sensor to up to 62% as a consequence of these developments, comparable to the quantum efficiency of backside-illuminated scientific CMOS sensors. Finally, we discuss the influence of the various process parameters on quantum efficiency and present a strategy for further improvement.

MoNCH is a hybrid pixel detector featuring 25 pm pixel pitch and analogue readout for X-ray imaging at synchrotron radiation (SR) facilities. Sub -pixel spatial resolution has been demonstrated using charge sharing and interpolation algorithms. The current prototype version, MoNCH0.4, features 19 different pixel architectures to assess the design choices and components for an optimised architecture to be used at SR facilities, and to explore the potential use of dynamic gain switching in fine pitch pixels for applications at X-ray free electron lasers (XFELs). Previous characterisation results of the pixel architectures without dynamic gain switching have shown noise levels as low as 21.7 e- r.m.s., which have now been pushed to sub -20 e- r.m.s at room temperature using standard 300 pm -thick silicon sensors. Achieving low noise values however requires high conversion gain and necessitates design choices such as the simplification of the pixel architecture (e.g. by limiting the available choice of in -pixel gains). These compromises ultimately restrain the available dynamic range and prevent the use of MoNCH with low -gain avalanche diodes (LGADs) or high -Z sensors because of the large signals (internal amplification and high photon energies, respectively) and of large leakage currents. In this paper, we will introduce the MoNCH project followed by a description of the current prototype along with characterisation results of the pixel architectures without dynamic gain switching for synchrotron applications with an emphasis on noise and dynamic range. These experimental results will be used to fine-tune the design of MoNCH0.5 to validate the final pixel design. This small prototype should also include additional features from the continuous developments of the PSD detector group towards a full-scale 2 x 3 cm2 MoNCH1.0.

This document presents the outcomes of a comprehensive survey conducted among early career researchers (ECRs) in academic particle physics. Running from September 24, 2022, to March 3, 2023, the survey gathered responses from 759 ECRs employed in 39 countries. The study aimed to gain insights into the career prospects and experiences of ECRs while also delving into diversity and sociological aspects within particle physics research. The survey results are presented in a manner consistent with the survey choices. The document offers insights for the particle physics community, and provides a set of recommendations for enhancing career prospects, fostering diversity, and addressing sociological dimensions within this field.

Due to their high frame rates and dynamic range, large area coverage, and high signal-to-noise ratio, hybrid silicon pixel detectors are an established standard for photon science applications at X-ray energies between 2 keV and 20 keV. These properties also make hybrid detectors interesting for experiments with soft X-rays between 200 eV and 2 keV. In this energy range, however, standard hybrid detectors are limited by the quantum efficiency of the sensor and the noise of the readout electronics. These limitations can be overcome by utilizing inverse Low-Gain Avalanche Diode (iLGAD) sensors with an optimized X-ray entrance window. We have developed and characterized a prototype soft X-ray iLGAD sensor bonded to the charge integrating 75 µm pixel JUNGFRAU chip. Cooled to −22°C, the system multiplication factor of the signal generated by an impinging photon is ≥ 11. With this gain, the effective equivalent noise charge of the system is ≤5.5 electrons root-mean-square at a 5 µs integration time. We show that by cooling the system below −50°C, single photon resolution at 200 eV becomes feasible with a signal-to-noise ratio better than 5.

To enhance the spatial resolution of the M & Ouml;NCH 25 mu m pitch hybrid pixel detector, deep learning models have been trained using both simulation and measurement data. Challenges arise when comparing simulation-based deep learning models to measurement-based models for electrons, as the spatial resolution achieved through simulations is notably inferior to that from measurements. Discrepancies are also observed when directly comparing X-ray simulations with measurements, particularly in the spectral output of single pixels. These observations collectively suggest that current simulations require optimization. To address this, the dynamics of charge carriers within the silicon sensor have been studied using Monte Carlo simulations, aiming to refine the charge transport modeling. The simulation encompasses the initial generation of the charge cloud, charge cloud drift, charge diffusion and repulsion, and electronic noise. The simulation results were validated with measurements from the M & Ouml;NCH detector for X-rays, and the agreement between measurements and simulations was significantly improved by accounting for the charge repulsion.

Experiments at synchrotron radiation sources and X-ray Free-Electron Lasers in the soft X-ray energy range (250 eV–2 keV) stand to benefit from the adaptation of the hybrid silicon detector technology for low energy photons. Inverse Low Gain Avalanche Diode (iLGAD) sensors provide an internal gain, enhancing the signal-to-noise ratio and allowing single photon detection below 1 keV using hybrid detectors. In addition, an optimization of the entrance window of these sensors enhances their quantum efficiency (QE). In this work, the QE and the gain of a batch of different iLGAD diodes with optimized entrance windows were characterized using soft X-rays at the Surface/Interface:Microscopy beamline of the Swiss Light Source synchrotron. Above 250 eV, the QE is larger than 55% for all sensor variations, while the charge collection efficiency is close to 100%. The average gain depends on the gain layer design of the iLGADs and increases with photon energy. A fitting procedure is introduced to extract the multiplication factor as a function of the absorption depth of X-ray photons inside the sensors. In particular, the multiplication factors for electron- and hole-triggered avalanches are estimated, corresponding to photon absorption beyond or before the gain layer, respectively.

The first demonstration of 2 kHz time-resolved serial crystallography data acquisition at a fourth-generation synchrotron, using the JUNGFRAU 4M pixel detector.

Single-photon detection of X-rays in the energy range of 250 eV to 1 keV is difficult for hybrid detectors because of the low quantum efficiency and low signal-to-noise ratio. The low quantum efficiency is caused by the absorption of soft X-rays in the entrance window of the silicon sensors. The entrance window consists of an insensitive layer on the surface and a highly doped layer, which is typically from a few hundred nanometers to a couple of micrometers thick and is comparable to the absorption depth of soft X-ray photons (e.g. the attenuation length of 250 eV X-ray photons is ∼100 nm in silicon). The low signal-to-noise ratio is mainly caused by the small signal amplitude (e.g. ca. 70 electrons for 250 eV X-ray photons in silicon) with respect to the electronic noise. To improve the quantum efficiency, the entrance window must be optimized by minimizing the absorption of soft X-rays in the insensitive layer, and reducing charge recombination at the Si-SiO2 interface and in the highly doped region. Low gain avalanche diodes (LGADs) with a multiplication factor between 5 and 10 increase the signal amplitude and therefore improve the signal-to-noise ratio for soft X-rays, enabling single-photon detection down to 250 eV. Combining LGAD technology with an optimized entrance window technology can thus allow hybrid detectors to become a useful tool also for soft X-ray detection. In this work we present the optimization of the entrance window by studying the internal quantum efficiency of eight different process technology variations. The sensors are characterized using light emitting diodes with a wavelength of 405 nm. At this wavelength, the light has an absorption depth of 125 nm, equivalent to that of 276 eV X-rays. The best variation achieves an internal quantum efficiency of 0.992 for 405 nm UV light. Based on this study, further optimization of the quantum efficiency for soft X-rays detection is planned.

The new fourth-generation storage rings (diffraction-limited storage rings, e.g., MAXIV, ESRF EBS, SLS2.0) will have a much higher brilliance than the third-generation sources increasing the photon flux at the pixel level. This will exceed the count rate capabilities of many of the single photon-counting detectors currently used, making them unsuitable to be used in future experiments at these machines. Matterhorn is a 2-D hybrid pixel detector developed by the PSD detector group of the Paul Scherrer Institut (PSI, Switzerland) to be used at SLS2.0. The main goal of this detector is to extend the count rate capability (target 20 Mcounts/pixel/s) by means of multi-threshold circuitry in the pixels.The final Matterhorn ASIC will have 256 x 256 pixels with 75 μm pitch, will be designed in UMC 110nm technology, and will be highly configurable. Each pixel will have a charge-sensitive amplifier and a shaper connected to four comparators. Each comparator will have an adjustable threshold that can be set to a value higher than the photon energy allowing to extend the count rate capability. Each comparator is connected to a 16-bit independently gateable counter. The target frame rate for reading out one 16-bit counter of all pixels is 10 kHz. Therefore, each ASIC will be equipped with four serial links operating at the clock frequency of 3.125 GHz provided by an on-chip PLL.The first prototype of the ASIC with 48 x 48 pixels was submitted in January 2023 and is expected back by June 2023. The pixels already include the four comparators and counters. In the periphery, two serial links working at a clock frequency of 1.6 GHz provided by an on-chip PLL are included. Moreover, the digital periphery can be configured to read one (selectable), two, three, or all the counters.In this contribution, we will show the working principle of this detector and all its foreseen functionalities. Moreover, the experimental results of the first prototype will also be shown.

The JUNGFRAU detector is a well-established hybrid pixel detector developed at the Paul Scherrer Institut (PSI) designed for free-electron laser (FEL) applications. JUNGFRAU features a charge-integrating dynamic gain switching architecture, with three different gain stages and 75 μm pixel pitch. It is widely used at the European X-ray Free-Electron Laser (EuXFEL), a facility which produces high brilliance X-ray pulses at MHz repetition rate in the form of bursts repeating at 10 Hz. In nominal configuration, the detector utilizes only a single memory cell and supports data acquisition up to 2 kHz. This constrains the operation of the detector to a 10 Hz frame rate when combined with the pulsed train structure of the EuXFEL. When configured in so-called burst mode, the JUNGFRAU detector can acquire a series of images into sixteen memory cells at a maximum rate of around 150 kHz. This acquisition scheme is better suited for the time structure of the X-rays as well as the pump laser pulses at the EuXFEL. To ensure confidence in the use of the burst mode at EuXFEL, a wide range of measurements have been performed to characterize the detector, especially to validate the detector alibration procedures. In particular, by analyzing the detector response to varying photon intensity (so called ‘intensity scan’), special attention was given to the characterization of the transitions between gain stages. The detector was operated in both dynamic gain switching and fixed gain modes. Results of these measurements indicate difficulties in the characterization of the detector dynamic gain switching response while operated in burst mode, while no major issues have been found with fixed gain operation. Based on this outcome, fixed gain operation mode with all the memory cells was used during two experiments at EuXFEL, namely in serial femtosecond protein crystallography and Kossel lines measurements. The positive outcome of these two experiments validates the good results previously obtained, and opens the possibility for a wider usage of the detector in burst operation mode, although compromises are needed on the dynamic range.