In nuclear synthesis experiments, particularly for the study of astrophysical nuclear synthesis such as neutron capture reaction under the high flux environmentof the ?-ray or neutron, an ultra-high intense neutron source is indispensable. The generation of high peak intensity neutron up to 109 neutron/shot within a 1.2-ps pulse duration from a 1-mm-sized gold target via photonuclear reaction was demonstrated by using LFEX laser. The hot electrons generated by LFEX laser irradiation creates ?-rays via Bremsstrahlung in the high Z material targets, and the ?-rays creates neutron via photo nuclear reaction from the material. The broad neutron spectrum from keV to MeV, which is preferable for the application of nuclear synthesis experiments was predicted by Monte Carlo simulation. The very stable neutron spectrum independent from the ?-ray spectrum was shown. The neutron flux at the target surface was 109/cm2/ps, therefore 1021 neutrons /cm2/s was estimated. The figure 1 shows the neutron spectrum generated from gold target via photo nuclear reaction, where black line and red line shows neutron generated by a ?-ray with the spectrum of 10-MeV-slope and 5-MeV-slope, respectively. The figure 2 shows the neutron yield obtained in the experiment by using 1-mm-thick 2-mm-diameter gold target and up to 1.6 kJ LFEX laser with the pulse width of 1.5 ps. Figure 1. <img src='https://acs-archive-assets2.s3.amazonaws.com/se_sw_rm/uploads/65884_wok2.jpg' alt='' />Figure 1. The photonuclear neutron spectrum from gold target. Every data plot indicates data bin. Black line shows neutron spectrum from 10-MeV-slope ?-rays and red line shows 5-MeV-slope ?-rays.Figure 2. The neutron yield observed from the 1-mm thick gold disc target irradiated with LFEX laser.

High intensity g-ray and neutron generation by ultra intense laser

248th National Meeting (2014)

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