Observation of neutrons in the interaction of high intensity laser pulses with solid targets

Abstract

Abstract.We report an experimental study on fusion neutron generation from deuterated polyethylene (CD 2 ) n target irradiated by 400 mJ, 45 femtosecond laser pulses focused to an intensity >10 18 W/cm 2 . The fusion neutron signal has been detected using a CR-39 detector, a bubble detector, and also confirmed by a neutron time of flight detector. In addition, substantial bremsstrahlung X-ray radiation of MeV energy was also observed. These MeV X-rays have been used to trigger ( , n) reaction in Be and Cu targets and the resulting photo-neutrons were detected on a BF 3 and a bubble detector.

D+D fusion reactions in 1018W/cm2intensity and repetitive laser-plasma interactions

“…Note that independent measurements of the fluxes deduced from the three scintillators are consistent within error bars. Moreover, our evaluation is in fair agreement with the values obtained in similar previous experiments [16,22]. These counts are unaffected by the neutron background, being performed by TOF measurements.…”

“…It is precisely in this line that fits our experiment, in which a few TW Ti:Sapphire laser was employed to produce D + D fusions in deuterated plastic targets. In this article, we demonstrate the possibility to produce neutrons at low laser peak intensity (≈ 10 18 W/cm 2 ), which is a factor 2 lower than what can be found in the literature [16,22]. In parallel, the energy of the deuterons responsible for the D + D fusion process has been measured and the laser-target interaction in which the fusion process develops was simulated through a Particle-In-Cell (PIC) coupled to a simplified nuclear reaction model.…”

“…Accelerated deuterons, colliding with deuterium atoms in the still solid target or with deuterium ions in the plasma, may give rise to D + D fusions, whose experimental signature is the detection of neutrons at an average energy of 2.45 MeV. Experiments of this kind have been successfully carried out in the 10 18 -10 19 W/cm 2 laser intensity range [16][17][18][19][20][21][22]. For instance, Pretzler et al [16] reported a neutron rate of 140 neutrons per shot using a 200 mJ-160 fs laser pulse into a focal spot of 4.5 μm diameter, while Norreys et al [17] has observed about 10 7 neutrons/sr using a 20 J-1.3 ps laser pulse into a focal spot of 12 μm diameter.…”