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Development & first Performance evaluation of multi-element monolithic HPGe detector for X-ray spectroscopy

N. Goyal, F. J. Iguaz, S. Aplin, A. Balerna, P. Bell, J. Casas, M. Cascella, S. Chatterji, C. Cohen, E. Collet, E. N. Gimenez, H. Graafsma, H. Hirsemann, K. Klementiev, T. Kolodziej, T. Martin, R. H. Menk, C. Menneglier, C. Meraihia, J. R. Murias, M. Porro, M. Quispe, B. Schmitt, S. Scully, M. Turcato, C. Ward, E. Welter

TL;DR

This work reports the development, laboratory characterization, and initial on-beam evaluation of XAFS-DET, a monolithic multi-element HPGe detector optimized for high-resolution X-ray spectroscopy in the hard X-ray regime. The system integrates a 10-element monolithic Ge sensor, TETRA-based front-end electronics, and Stirling-cycle cooling to enable high-rate operation (20-250 kcps/mm^2) across 5–100 keV, with a detailed defect-depth estimation model to quantify shallow charge-collection defects. On-beam measurements at ESRF BM05 reveal defect depths of 1–6 μm near the sensor entrance and demonstrate the feasibility of high-rate monochromatic spectroscopy, supported by a paralyzable dead-time model that aligns with lab measurements. Overall, the detector shows strong uniformity across most of the active area, with a path forward for substantial improvements via hardware (indium bump bonding, back-end isolation) and software (digital charge-sharing corrections) aimed at extending performance up to 100 keV for next-generation synchrotron applications.

Abstract

The first operational prototype of a high-purity Germanium (HPGe) detector developed within the European LEAPS-INNOV project is presented in this work. This prototype features a monolithic, multi-element sensor optimized for high-resolution X-ray spectroscopy in the hard X-ray regime, capable of handling high count rates (20-250 kcps/mm2) across a broad energy range (5-100 keV). We discuss here a complete laboratory-based characterization of the detector's performance, as well as an on-beam evaluation at the BM05 beamline of the ESRF synchrotron facility, using monochromatic X-rays in the 20-50 keV energy range. We provide a detailed performance assessment that also includes a phenomenological defect-depth estimation model.

Development & first Performance evaluation of multi-element monolithic HPGe detector for X-ray spectroscopy

TL;DR

This work reports the development, laboratory characterization, and initial on-beam evaluation of XAFS-DET, a monolithic multi-element HPGe detector optimized for high-resolution X-ray spectroscopy in the hard X-ray regime. The system integrates a 10-element monolithic Ge sensor, TETRA-based front-end electronics, and Stirling-cycle cooling to enable high-rate operation (20-250 kcps/mm^2) across 5–100 keV, with a detailed defect-depth estimation model to quantify shallow charge-collection defects. On-beam measurements at ESRF BM05 reveal defect depths of 1–6 μm near the sensor entrance and demonstrate the feasibility of high-rate monochromatic spectroscopy, supported by a paralyzable dead-time model that aligns with lab measurements. Overall, the detector shows strong uniformity across most of the active area, with a path forward for substantial improvements via hardware (indium bump bonding, back-end isolation) and software (digital charge-sharing corrections) aimed at extending performance up to 100 keV for next-generation synchrotron applications.

Abstract

The first operational prototype of a high-purity Germanium (HPGe) detector developed within the European LEAPS-INNOV project is presented in this work. This prototype features a monolithic, multi-element sensor optimized for high-resolution X-ray spectroscopy in the hard X-ray regime, capable of handling high count rates (20-250 kcps/mm2) across a broad energy range (5-100 keV). We discuss here a complete laboratory-based characterization of the detector's performance, as well as an on-beam evaluation at the BM05 beamline of the ESRF synchrotron facility, using monochromatic X-rays in the 20-50 keV energy range. We provide a detailed performance assessment that also includes a phenomenological defect-depth estimation model.

Paper Structure

This paper contains 19 sections, 11 equations, 18 figures, 5 tables.

Table of Contents

  1. Physics Motivation
  2. The XAFS-DET germanium detector
  3. Sensor Design
  4. Electronics
  5. Cooling and mechanical design
  6. Detector characterization in the laboratory
  7. Mean Signal risetime and preamplifier gain
  8. Power Spectral Density Measurements
  9. Fluorescence Measurements with lab X-ray generator source
  10. Energy Resolution $\&$ Count Rate Effects in Fluorescence Mode
  11. Dead time and pile-up studies
  12. Surface scanning: Micro spot beam
  13. Crosstalk between pixels
  14. Rise Time Scanning
  15. First On-beam tests
  16. ...and 4 more sections

Figures (18)

  • Figure 1: Schema (left) and photo (right) of XAFS-DET detector, described in detail in the text.
  • Figure 2: Schematic representation of the germanium sensor (left) and sensor dimensions (right).
  • Figure 3: Conceptual schema of the three BEB and the FEB, described in detail in the text.
  • Figure 4: (a) Test pulse response for the 10 channels of the FEB for high gain (b) and for channel 2 for high, medium and low gain settings.
  • Figure 5: Mechanical design of cooling chain and the associated components.
  • ...and 13 more figures