نتایج جستجو برای: neutrons
تعداد نتایج: 20708 فیلتر نتایج به سال:
We have developed a small, light, and multi-functional electronic personal dosimeter (EPD) using four semiconductor radiation detectors for dose monitoring of workers at nuclear power plants and high-energy accelerator facilities. This dosimeter is about 103 x 55 x 15 mm in size and approximately 110 g in weight, and capable of measuring gamma-ray and neutron doses in Hp(10), and beta-ray dose ...
A dose-limiting component of a proton accelerator-based source of epithermal neutrons is the neutron production target. Possible targets are lithium, producing high yield but having low melting point and thermal conductivity, and beryllium, presenting less engineering problems but a much smaller neutron yield. We propose that a hybrid Be-Li target would provide the best of both worlds, with the...
We present results from the measurement of the neutron production rate in lead by high energy cosmic-ray muons at a depth of 2850 m water equivalent (mean muon energy of 260 GeV). A tonne-scale highly segmented plastic scintillator detector was utilised to detect both the energy depositions from the traversing muons as well as the delayed radiative capture signals of the induced neutrons. Compl...
Solid deuterium (sD2) will be used for the production of ultra-cold neutrons (UCN) in a new generation of UCN sources. Scattering cross sections of UCN in sD2 determine the source yield but until now have not been investigated. We report first results from transmission and scattering experiments with cold, very cold and ultra-cold neutrons on sD2 along with light transmission and Raman scatteri...
A study was made on the loss of the reproductive capacity of HeLa S3 cells irradiated in vitro under both oxygenated and anoxic conditions with D-T neutrons (14 Mev) at 1, 20, 30, 150 and 400 rads/minute at 25•Ž and 37•Ž and with 180 kvp X-rays at 100 rads/minute at 37•Ž. 1) RBE of neutrons measured at a range of 2 to 10% survival was 2.67-2.62 under oxygenated conditions and 3.83.4.61 under an...
It is shown that the observation of the spectra of leading neutrons from proton beams can be a good probe of absorptive and migration effects. We quantify how these effects modify the Reggeized pion-exchange description of the measurements of leading neutrons at HERA. We are able to obtain a satisfactory description of all the features of these data. We also briefly discuss the corresponding da...
The penetration of 14-MeV neutrons into five representative soils is investigated with two independent neutron transport calculational procedures. From Monte Carlo and discreteordinates codes, the spatial distribution of the thermal fluence and the capture of neutrons in the soils is determined for two neutron source geometries. Finally, empirical approximations of the thermal neutron fluence i...
The neutron irradiation system for boron neutron capture therapy (BNCT) using compact accelerators installed at hospitals was mainly investigated for the usage of direct neutrons from near-threshold Li(p,n)Be, and moderated neutrons from 2.5 MeV Li(p,n)Be reactions and other reactions. This kind of system can supply the medical doctors and patients with convenience to carry out BNCT in hospital...
We have determined for the first time the velocity distribution of neutrons from a solid H2 ultracold neutron (UCN) source. The spectrum rises sharply above 4.5m/s and has a maximum around 7m/s after transport in an 8m long guide. The number of neutrons in the UCN velocity range (< 7m/s) may be increased by a factor of two by placing the experiment 1m above the UCN source level. PACS. 29.25.Dz ...
We present studies of Heliumand Argon-filled ionization chambers exposed to intense neutron fluxes from PuBe neutron sources (En = 1− 10 MeV). The sources emit about 10 neutrons per second. The number of ion pairs in the chamber gas volume per incident neutron is derived. While limited in precision because of a large gamma ray background from the PuBe sources, our results are consistent with th...
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