In order to develop a high spatial resolution (micron level) thermal neutrondetector, a detector assembly composed of cerium doped lithium glassmicrofibers, each with a diameter of 1\,$\mu$m, is proposed, where the neutronabsorption location is reconstructed from the observed charged particleproducts that result from neutron absorption. To suppress the cross talk of thescintillation light, each scintillating fiber is surrounded by air-filled glasscapillaries with the same diameter as the fiber. This pattern is repeated toform a bulk microfiber detector. On one end, the surface of the detector ispainted with a thin optical reflector to increase the light collectionefficiency at the other end. Then the scintillation light emitted by anyneutron interaction is transmitted to one end, magnified, and recorded by anintensified CCD camera. A simulation based on the Geant4 toolkit was developedto model this detector. All the relevant physics processes including neutroninteraction, scintillation, and optical boundary behaviors are si\-mulated.This simulation was first validated through measurements of neutron responsefrom lithium glass cylinders. With good expected light collection, an algorithmbased upon the features inherent to alpha and triton particle tracks isproposed to reconstruct the neutron reaction position in the glass fiber array.Given a 1\,$\mu$m fiber diameter and 0.1\,mm detector thickness, the neutronspatial resolution is expected to reach $\sigma\sim 1\, \mu$m with a Gaussianfit in each lateral dimension. The detection efficiency was estimated to be3.7\% for a glass fiber assembly with thickness of 0.1\,mm. When the detectorthickness increases from 0.1\,mm to 1\,mm, the position resolution is notexpected to vary much, while the detection efficiency is expected to increaseby about a factor of ten.
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