Abstract:
To verify whether the ultrafast neutron beam radii of the 100
MeV cyclotron developed by China Academy of Atomic Energy (CIAE) consists with the design requirements, the spatial distributions of the neutron field were measured experimentally for the first time using the self-developed Bulk MicroMegas micro-structured gaseous detector. Firstly, the transfer efficiencies of polyethylene (PE) converters with different thicknesses to ultrafast neutrons with different energies, the kinetic energy spectra and angular distributions of recoil protons, the deposition energy spectra of recoil protons in Bulk MicroMegas detector and the proportion of reaction products induced by incident neutrons reacted with detector structural materials were obtained through simulation calculations. Subsequently, the neutron flux distributions of the ultrafast neutron fields generated by the cyclotron at 28 positions were experimentally measured at different energies and distances using Bulk MicroMegas detector, and the beam radii profile was calculated according to the flux distribution. It is shown that the Bulk MicroMegas micro-structured gas detector can achieve the imaging of ultrafast neutron beam field boundary. The distribution of neutron flux at different distances to the beam center is in accordance with the commonly used beam boundary fitting functions. The measurement of beam radii is close to the simulation result.
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