Abstract:The characteristics of oxygen-enriched liquid scintillators with very low afterglow are investigated and optimized for application to a single-hit neutron spectrometer for fast ignition experiments. It is found that 1,2,4-trimethylbenzene has better characteristics as a liquid scintillator solvent than the conventional solvent, p-xylene. In addition, a benzophenon-doped BBQ liquid scintillator is shown to demonstrate very rapid time response, and therefore has potential for further use in neutron diagnostics w… Show more
“…TCSPC using radioactive sources is possible but is not straightforward since it usually requires very strict experimental conditions and days or even weeks of continuous recordings. 39 This timescale is higher than the potential stability of our materials. Thus, we decided to use the simplest method, which is recording thousand pulses and measure the time profile of the pulse.…”
“…TCSPC using radioactive sources is possible but is not straightforward since it usually requires very strict experimental conditions and days or even weeks of continuous recordings. 39 This timescale is higher than the potential stability of our materials. Thus, we decided to use the simplest method, which is recording thousand pulses and measure the time profile of the pulse.…”
“…The neutron energy spectrum was measured by the time of flight (TOF) method. A benzophenon-doped BBQ liquid scintillation detector with a size of 60 mm60 mm with a photomultiplier tube (PMT; Thron EMI, 9902KBT) [ 43 ] was located 8.3 m downstream from the center of the target chamber, and the angle between the laser axis and the TOF beam line was approximately 15, corresponding to 57 away from the normal vector of the Be target. The output signal from the PMT was recorded by an oscilloscope shot by shot and the neutron energy spectrum for each laser shot was obtained from each signal [ 44 ] . Figure 2 Experimental setup for the laser shot to generate neutrons.…”
We predict the production yield of a medical radioisotope 67 Cu using 67 Zn(n, p) 67 Cu and 68 Zn(n, pn) 67 Cu reactions with fast neutrons provided from laser-driven neutron sources (LDNSs).The neutrons were generated by the p+ 9 Be and d+ 9 Be reactions with high energy ions accelerated by laser-plasma interaction. We evaluated the yield to be (3.3±0.5)×10 5 atoms for 67 Cu, corresponding to a radioactivity of 1.0±0.2 Bq, for a Zn foil sample with a single laser shot. Using a simulation with this result, we estimated 67 Cu production with a high-frequency laser. The result suggests that it is possible to generate 67 Cu with a radioactivity of 270 MBq using a future laser system with a frequency of 10 Hz and 10000-s radiation in a hospital.
“…Hf is useful for various measurements because it has many isomers with half-lives of several hours in addition to unstable isotopes and some Hf isotopes are known are branching points for the s-process [45,46]. The neutrons in the MeV energy range were measured by the TOF method using a benzophenon-doped BBQ liquid scintillation detector (φ 60 mm × 60 mmt) with a photomultiplier tube (Thron EMI 9902KBT) (PMT) [47]. The detector was located at a position 8.3 m downstream from the neutron source and a direction of 15 • away from the laser axis and the spectrum exhibits neutrons passed through the moderator.…”
We produced high-energy neutrons by p+Be and d+Be reactions with protons and deuterons with continues energies of up to 30 and 10 MeV/u, respectively, provided from laser-plasma interactions. Thermal neutrons were subsequently generated through deceleration by a small moderator with conjunction on the Be target. Here we report the measurements on the thermal neutron fluence using the activation method with/without Cd filters. The unstable isotopes of 198Au, 56Mn, 60Co, and 181Hf were produced through (n, γ) reactions by a single laser shot. The nuclear reaction rates were evaluated by measuring the γ-rays emitted from these unstable isotopes. The thermal neutron fluences from the four nuclides are consistent within their experimental uncertainties. The fluence is evaluated to be (2.2±0.4)×105neutrons/cm2at the distance of approximately 9-mm at 90◦ against the laser axis. The present result shows that the method to generate thermal neutrons from a compact neutron source with a diameter of 44 mm and length of 46 mm is expected to be a useful tool for various nuclear experiments.
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