White-light neutron imaging method and non-destructive testing method for material composition using it

Abstract

A white light neutron imaging method comprises the following steps: a neutron source emits a pulse neutron beam and records emitting time; a detector detects the pulse neutron beam to acquire the position and the arrival time of neutrons and transmits the position and the arrival time to a processing unit; the processing unit acquires energy information of the neutrons according to the arrival time of the neutrons and the recorded emitting time and groups the neutrons according to energy to acquire two-dimensional neutron flux distribution phi1(E); and the steps are repeated to acquire two-dimensional neutron flux distribution phi2(E) when samples are placed, and a neutron transmission image with the neutron energy information is acquired according to the phi1 / phi2 value and the energy grouping information. The invention also provides a material composition nondestructive detection method. The material composition nondestructive detection method comprises the following steps: reestablishing three-dimensional space information by using position information acquired at different angles, combining with energy information to acquire transmission information of a space cell point, and comparing the value with an atomic nucleus database to determine the composition of the material. The composition of the material can be determined accurately under the nondestructive condition, and the measured neutron energy range is widest and can cover from eV to one hundred megabyte eV.

Description

technical field [0001] The invention belongs to the field of non-destructive testing, and more specifically relates to a white light neutron imaging method and a material composition non-destructive testing method using the same. Background technique [0002] Traditional neutron imaging devices usually use accelerator fission neutron sources or reactor neutron sources, and use scintillation screens to receive all incident neutrons, so the imaging process does not distinguish between particle energies, and the resulting images are actually neutrons of various energies. It is difficult to analyze the image in depth, and it is impossible to further analyze the structure and composition of the sample. [0003] In order to solve the above problems, neutron radiography research aimed at determining neutron energy has gradually emerged in recent years. The energy information of neutrons is obtained by using pulsed accelerator neutron sources and time-of-flight measurements, and th...

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Problems solved by technology

[0004] There are two implementation methods in neutron resonance imaging: one method is to use quasi-monoenergetic neutron beams, for example, in 2002, Chen Gongyin et al. of MIT proposed to use D-D reaction to obtain quasi-monoenergetic neutrons distributed according to the angle beam, and image the sample point by point to obtain a series of transmission images of energy points. However, this method needs to measure neutron energies in a wide energy range one by one, which is extremely inefficient and can only reflect fast neutrons with spectral resolution. The value of photos in the field of elemental analysis and security inspection; another method is to sort neutrons or related signals with a wider energy spectrum. The resulting images are sorted

Compared with the quasi-monoenergetic neutron beam, this method uses a sorting scheme to improve the utilization efficiency of the beam, shorten the imaging time, and can realize image acquisition of 4-8 fixed energy points; but this scheme is still only for the image Time screening does not directly measure a single particle event, and due to the low beam intensity, the flight length of neutrons is correspondingly shortened, so the energy range covered by neutrons intercepted through the time window is still very wide and cannot be analyzed by formants Obtain material information. In addition, because the scheme is mechanically rotated and collected, its image collection efficiency is low, which does not meet the needs of practical applications.

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