Neutron imaging is an invaluable tool for noninvasive analysis in many fields. However, neutron facilities are expensive and inconvenient to access, while portable sources are not strong enough to form even a static image within an acceptable time frame using traditional neutron imaging. Here we demonstrate a new scheme for single-pixel neutron imaging of real objects, with spatial and spectral resolutions of 100 lm and 0.4% at 1 Å, respectively. Low illumination down to 1000 neutron counts per frame pattern was achieved. The experimental setup is simple, inexpensive, and especially suitable for low intensity portable sources, which should greatly benefit applications in biology, material science, and industry.
Introduction To set up an online proton beam diagnostic system near the neutron production target of China Spallation Neutron Source (CSNS), a luminescence coating sprayed on the target window and a corresponding optic system were fabricated. In the work, the fabrication of Results The emission spectrum excited by 532-nm laser has two obvious peaks at 692.9 nm and 694.3 nm. The samples by flame spraying process with the powders obtained from melting method show higher luminescence intensity than the samples by plasma spraying process. It is observed that the luminescence intensity has some relationships with the alpha phase in the samples, which is deduced from the XRD and photoluminescence tests results. A lower temperature during the flame spraying process will help to keep more alpha phase in the material. The selected four samples show successful fluoresced results in the radioluminescence experiment. Conclusions The luminescence intensity of the coating is improved greatly by the studies on the fabrication process and the characteristics of the samples. The luminescence coating used in beam diagnostics will be fabricated by the confirmed technical process. More works will be continued to improve the characteristics of the luminescence light by controlling Cr concentration and annealing in 1200 ∼ 2000 • C environment in the future.
The Monte Carlo intra-nuclear cascade program CBIM has been developed for describing spallation reactions involving protons, neutrons and pions on complex nuclei.
In order to describe cascade process, several simplifications and assumptions are made in the following:firstly, neither reaction, nor reflection, nor refraction, nor ionization will be taken into account before the incident particle enters into the target nucleus; secondly, target nucleus is regarded as being spherical and the atom number should be greater than 2; thirdly, the knocked nucleon is determined by cross section sampling; finally, in the center-of-mass frame, the scattering angle is sampled based on differential cross section distribution.
The basis physics model is based on the above assumptions and Bertini intra-nuclear cascade model; meanwhile, nucleon-nucleon angle differential distributions of INCL in the center-of-mass frame are introduced to overcome the shortage of Bertini model. The interactions between nucleon and nucleon or between nucleon and pion, such as elastic scattering, pion production and charge exchange, are included in the code. In the particles collision, the nucleon density changes with the target nucleus radius; and the interaction cross sections refer to 22 kinds of experimental cross sections in Bertini model. The intra-nuclear cascades induced by 45-3500 MeV neutron, proton or pion below 2500 MeV can be simulated by this code.
Finally, comparisons between experimental reaction cross section over the energy range 60-378 MeV, and some simulation results by MCNPX, GEANT4 and PHITS over the energy range 65-3000 MeV show that they are in reasonable agreement with the CBIM results over the broad energy range considered.
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