Speaker
Description
Facilities that provide bright thermal neutron beams are crucial for a wide range of research areas, including condensed matter experiments, neutron imaging, and medical applications. Currently, these beams are primarily generated by spallation sources and nuclear research reactors. However, many of these facilities are aging, and the current political climate does not favor the construction of new ones. For instance, the Orphee reactor at CEA-Saclay in France was shut down in 2019. Consequently, there is a need for an alternative, affordable facility that can be built by a single country and is capable of producing high-brilliance neutron beams.At CEA-Saclay, a compact accelerator driven neutron source is investigated in levaraging the IPHI accelerator, which can deliver a 3 MeV proton beam with an intensity of up to 100 mA. The high-energy primary neutrons (~MeV) produced by the interaction between the beam and the target are then slowed down in a moderator to room temperature (~25 meV) and subsequently directed to an experimental setup for use.
Since 2016, an experimental program has been underway to demonstrate the feasibality of operating a high power beryllium target of 50 kW for the proposed French compact neutron source ICONE [1]. In addition to the challenges to operate such high intensity accelerators, the other conern the design of the target-moderator-reflector (TMR) system, which is essential for maximizing neutron flux at the detector location. To address this, the TOUCANS code [2] based on Geant4 [3] has been developed to demonstrate the feasibility and determine the optimal TMR configuration. From 2016 to 2022, three different beryllium targets and TMR systems were developed to handle increasing deposited power increasing from 10 W [4] to 3 kW [5], and ultimately to 30 kW for 100 hours [6]. Each time, the extracted thermal neutron beam was optimized using the TOUCANS code, characterized, and compared with simulation predictions. Additionally, in the most recent configuration, the thermal neutron beam was utilized to perform diffraction measurements.
In parallel with the development of beryllium targets, a liquid lithium target named SATELIT (Saclay Target with Liquid Lithium) has been under development since 2021 to maximize neutron production and, consequently, neutron flux. In 2024-2025, SATELIT was successfully coupled with the IPHI accelerator. For the first time, a 10 kW proton beam was directed at a liquid lithium target for a total irradiation time of 100 hours. During the experimental measurement campaign, the neutron beam was characterized and compared with Geant4 simulation predictions. Additionally, the thermal neutrons were successfully utilized for diffraction measurements and neutron imaging.
The European context of the CANS developments, along with the progress made at CEA-Saclay, will be discussed. The focus will be on the latest experimental campaign conducted with SATELIT (the Saclay Target with Liquid Lithium), as well as the future steps expected to be performed.
References :
[1] ICONE https://2fdn.cnrs.fr/wp-content/uploads/2023/09/ICONE-digital.pdf
[2] L. Thulliez, B. Mom, and E. Dumonteil. TOUCANS: A versatile Monte Carlo neutron transport code based on GEANT4. Nucl. Instrum. Methods Phys. Res. A, 1051:168190, 2023.1545 (ISSN 0168-9002) doi: https://doi.org/10.1016/j.nima.15462023.168190.
[3] J. Allison et al., 2016. Recent developments in Geant4. Nucl. Instrum. Meth ods Phys. Res. A (ISSN: 0168-9002) 835, 186–225. http://dx.doi.org/10.1016/J.NIMA.2016.06.125,
[4] H.N. Tran et al. Neutrons production on the IPHI accelerator for the validation of the design of the compact neutron source SONATE. EPJ Web Conf., 231:01007, 2020. doi: 10.1051/epjconf/202023101007.
[5] L. Thulliez et al. First steps toward the development of SONATE, a Compact Accelerator driven Neutron Source. EPJ Web Conf., 239:17011, 2020. doi: 10.1051/epjconf/202023917011.
[6] J. Schwindling et al.. Long term operation of a 30 kW Beryllium target at IPHI. Journal of Neutron Research, 24(3-4):289–298, 2022. doi: 10.3233/JNR-220024.
