Natural neutron spectrum measurement method

Abstract

The invention relates to a natural neutron spectrum measurement method, which comprises the following steps: using natural water body as a neutron moderation body, using a Monte-Carlo method for analog computation of fluence energy response functions of a detector to a natural neutron when the detector is located at different depths in the natural water body; using the detector to measure the counting rate of the natural neutron at different depths in the water; using spectrum unfolding software for spectrum unfolding on the basis of the counting rate after background deducting and the obtained fluence energy response functions to obtain a natural neutron spectrum. According to the natural neutron spectrum measurement method, the natural water body is used as as semi-infinite moderation body, the defects of limited size of conventional processed moderation body is overcome, the influences of neutrons and other background generated in the moderation body during natural neutron measurement are effectively eliminated, high-energy neutrons in the natural neutron spectrum can be effectively measured, the operation is simple, and reliable results can be provided.

Description

technical field [0001] The invention belongs to the technical field of neutron measurement, in particular to a natural neutron energy spectrum measurement method. Background technique [0002] Natural neutrons are part of natural radiation. The energy range of natural neutron radiation field is roughly 0.0253eV-1000MeV, and the energy spans 11 orders of magnitude. The measurement of natural neutron energy spectrum has always been a relatively complicated problem. [0003] Currently commonly used neutron detectors include threshold detectors, nuclear recoil detectors, nuclear reaction detectors, and fission detectors. Generally, a detector can only measure neutrons in a specific energy region satisfactorily. To measure the entire energy region, a combination of multiple detectors (sometimes multiple types of detectors) must be considered. Considering the low level of natural neutron fluence rate (about 0.01 neutron·cm-2·s-1) and wide energy range, multi-sphere neutron spect...

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Problems solved by technology

[0006] However, there are two problems when the multi-sphere neutron spectrometer is used for natural neutron spectrum measurement: ① The maximum diameter of the moderator selected for site neutron spectrum measurement is ~40cm, and it is mostly used for neutron energy below 20MeV. Measurement, it is difficult to meet the requirements for natural neutron measurement, and the moderator with a larger diameter has many inconveniences in the process of processing and use; ② If the diameter of the moderator exceeds 10cm, when used for natural neutron measurement, The contribution of additional neutrons generated inside the detector due to various primary interactions should be considered, otherwise it will cause problems such as high neutron fluence rate and hard energy spectrum given by the analysis results

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