Continuous high-yield fast neutron generation with few-cycle laser pulses at 10 Hz for applications

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Abstract
We present a laser-based neutron source that produces 1.8 × 10 5 neutrons/s with a conversion rate of 7.8 × 10 5 neutrons/J . Laser pulses of 12 fs and 23 mJ were focused onto a 430 -nm -thick heavy water liquid sheet at a 10 Hz repetition rate. The resulting peak intensity of 4 × 10 18 W/cm 2 accelerated deuterium ions from the target rear side to a kinetic energy of 1 MeV. This deuteron beam induced H 2 ( d , n ) 3 He fusion reactions in a deuterated polyethylene target, producing fast neutrons. The neutron yield was measured using two independent detection systems: the LILITH time-of-flight spectrometer, consisting of eight plastic scintillators covering nearly 180 ∘ , and a calibrated bubble detector spectrometer. The neutron yield per laser shot is 35 times higher than that recently achieved by lasers with comparable pulse energies, while the conversion rate is the highest ever achieved by continuously operating, sub-100 fs lasers. The generated neutrons are emitted from an area of 0.65 cm 2 corresponding to the deuteron beam spot on the catcher. Their angular distribution is peaked in forward and backward directions in agreement with the literature data on the angular distribution of H 2 ( d , n ) 3 He reaction. The system operated continuously for several hours per day with an unprecedented stability of 5 % .
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Funding Information
  • Nemzeti Kutatási Fejlesztési és Innovációs Hivatal (NKFIH-877-2/2020, NKFIH-476-4/2021)
  • European Commission (101020100)
  • European Regional Development Fund (GINOP-2.3.6-15-2015-00001)
  • Institute for Basic Science (IBS-R031-D1)

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