162 / 2025-03-15 23:34:17

Laser-Driven Ultra-Intense Particle Sources and Applications in CLAPA

Laser nuclear physics; photonuclear reaction; Isomer; (epi-)thermal neutron

Electron beams, high-energy γ beams, and neutron beams driven by intense lasers possess the characteristics of being ultra-short and ultra-strong, and they have important application values in nuclear physics, nuclear medicine, nuclear reactors, material identification, FLASH radiotherapy, and other fields. By using the large-charge near-monoenergetic electron beams accelerated by the wakefield of the 200 TW laser in the CLAPA Laboratory of Peking University, bremsstrahlung γ rays with an intensity of over 10²⁰/s (>8 MeV) can be generated, and the duration is only on the sub-picosecond scale [1]. With the laser γ source, we have measured the cross sections of more than 170 photonuclear reactions of multiple elements such as ¹⁹⁷Au(γ, xn; x = 1~9) [1], ²⁰⁸Bi(γ, xn; x = 1~9), and ⁹⁶Ru(γ, n/p/np) [3,4]. For the first time internationally, the cross-section data of dozens of reaction channels have been obtained. Meanwhile, significant progress has been made in the online measurement of laser-driven nuclear reactions. The online measurement of the products of short-lived photonuclear reactions has been successfully achieved, and the cross-section data of the ¹¹⁵In(γ, n)^114m2In reaction with a half-life of only 43.1 ms has been measured [5], providing a unique approach to deeply understanding ultra-short-lived isomers and promising to fill the gaps in relevant experimental data. The multi-photon neutron reactions generated by the laser γ source and the photofission reaction of the Th element have produced an ultra-strong neutron source, and short-pulse (super)thermal neutron beams have been generated through moderation, which is of great significance in material detection, calibration of fission detectors, and other aspects. Based on the research on the photonuclear reactions of Th, a simulation study of using the ²³²Th(γ, 3n)^229mTh reaction as a pumping source for a new generation of nuclear clocks has been further proposed. In addition, certain progress has also been made in radioactive drug production, photonuclear activation material detection, γ imaging, and other aspects.