Fabrication of disk-shaped, deuterated resorcinol/formaldehyde foam target for laser–plasma experiments

Resorcinol/formaldehyde (RF) foam resin is an attractive material as a low-density target in high-power laser–plasma experiments because of its fine network structure, transparency in the visible region, and low-Z element (hydrogen, carbon, and oxygen) composition. In this study, we developed disk-shaped RF foam and deuterated RF foam targets with 40–200 µm thickness and approximately 100 mg/cm3 density having a network structure from 100 nm to a few micrometers cell size. By deuteration, the polymerization rate was drastically slowed down owing to kinetic isotope effects. These targets were used in high-power laser experiments where a megaelectronvolt proton beam was successfully generated.Kaneyasu Y., Nagai K., Cadatal-Raduban M., et al. Fabrication of disk-shaped, deuterated resorcinol/formaldehyde foam target for laser–plasma experiments. High Power Laser Science and Engineering 9, e31 (2022); https://doi.org/10.1017/hpl.2021.15

High Flux Neutrons Provided by a Laser driven Neutron Source and its Application to Nuclear Astrophysics

We demonstrated that (n, 2n) and (n, gamma) reactions are induced by a high-flux pulse of fast neutrons provided from a Laser-driven Neutron Source (LDNS). Several kinds of metal targets are exposed to the fast neutrons with energies of approximately 10-20 MeV. As a result, 180Hfm,181Hf, 56Mn, 198Au, and 60Co are produced by (n, gamma) reactions. Furthermore, unstable isotopes such as 54Mn, 58Co, 175Hf, and 196Au are produced by (n, 2n) reactions. We evaluate the neutron fluence and energy spectrum using the activation method in conjunction with a time-of-flight (TOF) method.The 16th international symposium on nculei in cosmo

Direct evaluation of high neutron density environment using (n,2n) reaction induced by laser-driven neutron source

We demonstrated that (n, 2n) and (n, gamma) reactions are induced by a high-flux pulse of fast neutrons provided from a Laser-driven Neutron Source (LDNS). The maximum energy of the broadband neutrons reaches a few tens MeV. Several kinds of metal targets are exposed to the fast neutrons. As a result, unstable isotopes such as 54Mn, 58Co, 175Hf, and 196Au are produced by (n, 2n) reactions and 180Hfm,181Hf, 56Mn, 198Au, and 60Co are produced by (n, gamma) reactions. We evaluate the neutron fluence and energy spectrum using the activation method in conjunction with a time-of-flight (TOF) method. The present scheme provides a method to evaluate high density neutrons seen in stellar environments, which are expected to be generated from future LDNSs

レーザー駆動熱外中性子源による中性子共鳴吸収計測

大阪大学レーザー科学研究所の大強度レーザーLFEXを水素を含むターゲットに集光し数十MeVの陽子を加速し、近接したBeターゲットに陽子を照射し核反応で中性子を生成した。この中性子にモデレーターを設置して時間分解能の劣化を抑えつつ中性子を部分的に減速させた。この中性子パルスを用いて金属ターゲットを透過後に飛行時間計測法で中性子のエネルギースペクトルを計測した。物質の種類によって固有の中性子共鳴吸収エネルギーがあり分析可能である。本手法で中性子共鳴吸収を計測した。日本物理学会　第76回年次大

レーザー駆動中性子源の宇宙核物理学への応用 -カドミウム差分法による中性子数の評価-

大阪大学レーザー科学研究所の大強度レーザーLFEXを水素を含むターゲットに集光し数十MeVの陽子を加速し、近接したBeターゲットに陽子を照射し核反応で中性子を生成した。この中性子のエネルギースペクトルは飛行時間計測法等で計測されているがエネルギー領域に限界があった。この中性子を用いて恒星の中の中性子捕獲反応過程を研究するために、中性子を金属ターゲットに照射しカドミウム差分法を用いて中性子のフラックを評価した。日本物理学会　第76回年次大