Synchrotron-based Photonuclear Neutron Source for Energy, Medicine and Radiation Testing

TL;DR

The paper introduces SYNERGY, a synchrotron-driven photoneutron source that decouples electron acceleration from neutron production by using a storage ring to emit photons that strike external targets. This CW photon-driven approach reduces target heating and enables beamline powers around $200$ kW, with up to 50 independent beamlines delivering a total neutron intensity exceeding $6.0\times10^{16}$ n/s. Through a systematic Monte Carlo study using OpenMC, MCNPX, and FLUKA, the authors optimize target geometry and materials (low-Z moderators and high-Z converters) to achieve neutron yields of $Y_n$ on the order of 10$^{-3}$–10$^{-2}$ neutrons per incident gamma, leading to per-beamline neutron rates of roughly $3\times10^{14}$ to $1.3\times10^{15}$ n/s. The facility’s versatility is demonstrated across applications including ADS, isotope production, BNCT, and soft-error testing, with significant performance advantages over existing compact sources and a compelling multi-user, multi-channel capability for future large-scale neutron science and medical applications.

Abstract

The global availability of high-intensity neutron sources is restricted by the prohibitive costs of spallation facilities and the decommissioning of aging research reactors, while compact accelerator-driven sources (CANS) are fundamentally limited by target power density and thermal-mechanical stress. Here, we introduce SYNERGY (SYnchrotron-driven NEutron source for Research, energy Generation and therapY), a paradigm-shifting architecture that overcomes these bottlenecks by decoupling charged-particle acceleration from neutron production. By utilizing a storage ring to drive external photoneutron targets via synchrotron radiation, this topological separation ensures targets interact exclusively with a continuous-wave (CW) photon beam, minimizing thermo-mechanical shocks and enabling beam powers exceeding 200 kW per beamline. Through a systematic parametric analysis cross-validated using OpenMC, MCNPX, and FLUKA, we demonstrate single-beamline neutron production rates from $2.8\times10^{14}$ n/s to $1.3\times10^{15}$ n/s. With an inherent multi-beamline capacity feeding up to 50 independent stations, the total facility intensity exceeds $6.0\times10^{16}$ n/s. By bridging the gap between laboratory and national-scale infrastructure, SYNERGY provides a high-intensity, multi-user platform for subcritical systems, medical isotope production, and boron neutron capture therapy.

Figures (8)

• Figure 1: Classification of neutron sources and their application domains based on neutron intensity. Data adapted from Kiyanagi2021. FP = Fundamental Physics; BNCT = Boron Neutron Capture Therapy; ADS = Accelerator Driven Systems.
• Figure 2: Illustrative example of a multi-beamline synchrotron-based facility, where a single storage ring feeds multiple photon beamlines.
• Figure 3: Energy distribution of the incident synchrotron radiation considering a beam power of 200 kW. The total source rate in the energy range 1-37 MeV is evaluated to be $2.02\times10^{17}~\gamma/s$
• Figure 4: Photonuclear cross-sections for representative Low-Z and High-Z isotopes. Top Panel: Low-Z isotopes (Deuterium and Beryllium) characterized by low threshold energies. The plot highlights the discrepancy for the $^{2}$H($\gamma,n$) reaction between the standard ENDF/B-VII.1 library (dashed line) and the JENDL-5 library (solid line) as reviewed in Sari2023. Bottom Panel: High-Z isotopes (Tantalum and Uranium) dominated by the Giant Dipole Resonance (GDR). For ${}^{238}$U, the specific contributions of $(\gamma, n)$, $(\gamma, 2n)$, and photofission $(\gamma, F)$ channels are explicitly shown. These data are in very good agreement with experimental measurements from Caldwell et al.Caldwell1980
• Figure 5: Schematic representation of the cylindrical target geometry used for parametric optimization.