Isomers, ubiquitous populations of relatively long-lived nuclear excited states, play a crucial role in nuclear physics. However, isomers with half-life times of several seconds or less barely had experimental cross section data due to the lack of a suitable measuring method. We report a method of online { \gamma} spectroscopy for ultra-short-lived isomers from photonuclear reactions using laser-driven ultra-intense { \gamma}-rays. The fastest time resolution can reach sub-ps level with { \gamma}-ray intensities >10^{ 19}/s ({ \geqslant} 8 MeV). The ^{ 115}In({ \gamma}, n)^{ 114m2}In reaction (T_{ 1/2} = 43.1 ms) was first measured in the high-energy region which shed light on the nuclear structure studies of In element. Simulations showed it would be an efficient way to study ^{ 229m}Th (T_{ 1/2} = 7 { \mu}s), which is believed to be the next generation of nuclear clock. This work offered a unique way of gaining insight into ultra-short lifetimes and promised an effective way to fill the gap in relevant experimental data.
Categories: nucl-ex physics.plasm-ph