Speaker
Description
Laser - plasma generation of ultra-short intense neutron pulse
$^1$Andreev А.А., $^2$Komarov V.А, $^3$Platonov К.Yu.
$^1$Saint-Petersburg State University, 199034 UniversitetskayaEmb. 7-9, St. Petersburg, Russia
$^2$FGUP scientific research institute of Complex Tests of Optiko-electronic Devices 188540, Leningrad region, Sosnovy Bor
$^3$Peter the Great St. Petersburg Polytechnic University,
195251 Polytechnicheskaya st. 29, St. Petersburg, Russia
Acceleration of Deytron nuclear in thin (micron size) laser targets (polyethylene C$_2$D$_4$) to a МэВ energy and the subsequent interaction with the secondary targets from D$_2$O, LiF, Be of 1 mm thickness was considered. It is shown, that at the energy of laser pulse of 250 J, duration 10 ps, diameter of the laser spot 5 microns and intensity 1.3x10$^{20}$ W/cm$^2$ in a secondary target there is the generation of ultrashort (<30 ps) neutron pulse containing from 4x10$^9$ (for LiF secondary target) to 10$^{10}$ neutrons (Be target) with characteristic energy about 10 MeV. Pulse intensity of a neutron flux from a surface of a secondary target reaches 10$^{20}$ neutrons/cm$^2$s, that exceeds the intensity of neutron flux of the reactors making in a continuous regime ~10$^{15}$ neutrons/cm$^2$s. Angular distribution of neutrons has a maximum in laser pulse direction and semi-width about ±60$^o$ from this direction is calculated. At 10 Hz repetition rate of a laser pulse, the realization quasi-stationary neutrons source with average intensity about 10$^{12}$ neutrons/cm$^2$s is possible. In laser-plasma neutron source a laser pulse with less (~ 100 fs) duration and upper (up 1 kHz) repetition frequency may be used. Peak intensity of a neutron flux thus will decrease on 2 order, however average intensity will remain constant. Despite of smaller average intensity and essentially smaller total number of neutrons, some potential application of laser-plasma super-short neutron pulses can be interesting for neutron spectroscopy of ultrafast (tens ps) physical, chemical and biological processes, which cannot be realized by means of traditional neutron sources.
