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ELIGANT-TN -- ELI Gamma Above Neutron Threshold: The Thermal Neutron setup

P. -A. Söderström, D. L. Balabanski, M. Cuciuc, D. M. Filipescu, I. Gheorghe, A. Kuşoğlu, C. Matei, D. Testov, S. Aogaki, H. T. Aslani, L. Capponi, D. Choudhury, G. Ciocan, T. Glodariu, M. Krzysiek, V. Lelasseux, R. Roy, R. F. Andrei, M. Brezeanu, R. Corbu, A. Dhal, D. Iancu, D. Kahl, S. Ioannidis, K. KeunHwan, G. Lorusso, B. Mauyey, T. Petruse, G. V. Turturică

TL;DR

ELIGANT-TN is a neutron-counter array at ELI-NP designed for high-precision cross-section measurements above the neutron threshold. It combines 28 $^{3}$He detectors in a large HDPE moderator with a digital readout chain and Geant4/MCNP simulations to quantify efficiency, timing, and energy-discrimination capabilities. Source tests with PuBe and $^{252}$Cf validate the simulation framework and performance, while in-beam commissioning on the $^{13}$C$(\alpha, n)$^{16}$O reaction demonstrates the ring-ratio method to infer neutron energy populations and ground-state feeding, enabling extraction of partial cross sections. The study demonstrates the viability of ELIGANT-TN for photonuclear measurements at ELI-NP and provides a detailed path for optimization and future experiments in nuclear astrophysics, industry, and medicine.

Abstract

Here we present the thermal neutron counter from the ELI Gamma Above Neutron Threshold setup at the Extreme Light Infrastructure - Nuclear Physics. We describe the mechanical design of the setup, the properties of the ${}^{3}$He gas counters, and the hardware data-acquisition electronics and software digital signal processing. The performance of the complete detector array is demonstrated via Geant4 and MCNP simulations, and measurements with typical neutron sources. The analysis procedure for experimental measurements are outlined with a in-beam test experiment with an $α$ beam to measure the ${}^{13}\mathrm{C}(α,\mathrm{n}_{0}){}^{16}\mathrm{O}$ cross-section branching ratios.

ELIGANT-TN -- ELI Gamma Above Neutron Threshold: The Thermal Neutron setup

TL;DR

ELIGANT-TN is a neutron-counter array at ELI-NP designed for high-precision cross-section measurements above the neutron threshold. It combines 28 He detectors in a large HDPE moderator with a digital readout chain and Geant4/MCNP simulations to quantify efficiency, timing, and energy-discrimination capabilities. Source tests with PuBe and Cf validate the simulation framework and performance, while in-beam commissioning on the C^{16}$O reaction demonstrates the ring-ratio method to infer neutron energy populations and ground-state feeding, enabling extraction of partial cross sections. The study demonstrates the viability of ELIGANT-TN for photonuclear measurements at ELI-NP and provides a detailed path for optimization and future experiments in nuclear astrophysics, industry, and medicine.

Abstract

Here we present the thermal neutron counter from the ELI Gamma Above Neutron Threshold setup at the Extreme Light Infrastructure - Nuclear Physics. We describe the mechanical design of the setup, the properties of the He gas counters, and the hardware data-acquisition electronics and software digital signal processing. The performance of the complete detector array is demonstrated via Geant4 and MCNP simulations, and measurements with typical neutron sources. The analysis procedure for experimental measurements are outlined with a in-beam test experiment with an beam to measure the cross-section branching ratios.

Paper Structure

This paper contains 9 sections, 8 equations, 22 figures, 2 tables.

Table of Contents

  1. Introduction
  2. Mechanical Design
  3. $^{3}$He detectors
  4. High Voltage
  5. Data Acquisition
  6. Geant4 and MCNP Simulations
  7. Source tests
  8. In-beam measurements of $(\alpha,\mathrm{n})$ reactions
  9. Summary and conclusions

Figures (22)

  • Figure 1: Photograph of the ELIGANT-TN neutron counter.
  • Figure 2: Drawing of ELIGANT-TN as viewed from the front (downstream). The size of the shielding as well as the radii of the three rings containing $^{3}$He counters are shown in the units of mm.
  • Figure 3: Drawing of the $^{3}$He tubes in ELIGANT-TN. The thickness of the anode wire is not to scale.
  • Figure 4: X-ray of one of the $^{3}$He tubes in ELIGANT-TN (top) with a high-contrast view on the anode wire (bottom).
  • Figure 5: Count rate as a function of high voltage of the $^{3}$He counters distributed via three pre-amplifiers (circles, triangles, pluses), for the tubes in the inner ring (green), middle ring (red), and outer ring (blue).
  • ...and 17 more figures