CN-121741810-B - Double neutron detector integrated in same position, logging instrument and application method

CN121741810BCN 121741810 BCN121741810 BCN 121741810BCN-121741810-B

Abstract

The invention discloses a double neutron detector integrated at the same position, a logging instrument and an application method, and belongs to the field of uranium mine exploration logging. The dual neutron detector comprises a first scintillation crystal, a second scintillation crystal, a photoelectric converter and a supporting part, wherein the first scintillation crystal and the second scintillation crystal are sensitive to thermal neutrons and are arranged in a similar surface laminating mode, the first scintillation crystal, the second scintillation crystal and the photoelectric converter form a detection part for reading out a common optical path along the same axial direction, the supporting part is fixedly arranged on the outer side of the detection part and supports the detection part as an integral component, shielding and slowing layers are arranged on the outer wall surface of the first scintillation crystal except a laminating area, the dual neutron detector is installed on the logging instrument, when the dual neutron detector is used, the first scintillation crystal and the second scintillation crystal are marked in the same thermal neutron field, spatial consistency errors are structurally eliminated through the design of the positions of the dual scintillation crystals, and the electronic hardware structure of the detector is simplified through the common optical path reading out design, so that the detector module is convenient to integrate.

Inventors

JIANG HUALEI
GE KE
LI GANG
WANG LIANG
SUN YUANYUAN
ZHANG ZAODI

Assignees

中国科学院合肥物质科学研究院

Dates

Publication Date: 20260512
Application Date: 20260228

Claims (8)

1. The double neutron detector integrated at the same position is characterized by comprising a first scintillation crystal, a second scintillation crystal, a photoelectric converter and a supporting part, wherein the first scintillation crystal and the second scintillation crystal are crystals sensitive to thermal neutrons; the first scintillation crystal and the second scintillation crystal are marked in the same thermal neutron field to calculate a ratio of thermal neutron detection efficiencies between the crystals to determine a ratio of the first scintillation crystal to the epithermal neutron detection efficiency and the second scintillation crystal to the thermal neutron detection efficiency; The photoelectric converter is arranged on the end face of the thermal neutron detection unit far away from the epithermal neutron detection unit in a coupling way, and the epithermal neutron detection unit, the thermal neutron detection unit and the photoelectric converter form a detection part for reading a common optical path along the same axial direction, wherein the shielding moderation layer comprises a shielding layer and a moderation layer arranged in the shielding layer, the moderation layer is coated on all the outer wall faces of the first scintillation crystal, and the shielding layer is coated on the outer wall face of the moderation layer; The supporting part is fixedly arranged on the outer side of the detecting part, and the supporting part is an integral component.
2. The co-located integrated dual neutron detector according to claim 1, wherein the first scintillation crystal is selected from 6 Li glass, ce: liCAF, 6 LiF/ZnS (Ag), CLLB, liI (Eu), stilbene crystal or EJ-299 plastic scintillator; The second scintillation crystal is selected from 6 Li glass, ce, liCAF, 6 LiF/ZnS (Ag), CLLB, liI (Eu), stilbene crystal or EJ-299 plastic scintillator.
3. The co-located integrated dual neutron detector according to claim 1, wherein the support portion is provided as a closed shell surrounding the detection portion; The closed shell comprises a first shell and a second shell, wherein the first shell is provided with a cavity structure with an opening at one end, the second shell is connected to the first shell and at least comprises an end cover for closing the opening, a cavity for accommodating the detection part is formed between the first shell and the second shell, and the detection part is detachably and fixedly arranged in the cavity structure.
4. The co-located integrated dual neutron detector according to claim 1, wherein the first scintillation crystal and the second scintillation crystal are regular hexahedral structures of identical shape.
5. A dual-neutron logging instrument integrated at a same position, comprising a pulsed neutron source, a dual-neutron detector, a detector power supply, and a data acquisition and processing module, wherein the dual-neutron detector is the dual-neutron detector integrated at a same position as any one of claims 1-4.
6. The dual neutron logging instrument integrated at the same position according to claim 5, wherein the data acquisition and processing module comprises a preamplifier, an analog-to-digital converter and an FPGA processor, wherein a pulse counting module and a time spectrum analysis module are configured in the FPGA processor, the detector power supply is connected to the photoelectric converter, the photoelectric converter receives optical signals and outputs electric signals through a common optical path reading structure formed by the photoelectric converter, the epithermal neutron detection unit and the thermal neutron detection unit, the output end of the photoelectric converter is connected to the preamplifier, the output end of the preamplifier is connected to the analog-to-digital converter and is used for converting the electric signals output by the photoelectric converter into digital signals after being amplified and shaped, the output end of the analog-to-digital converter is connected to the FPGA processor and is used for counting thermal neutrons and counting information of epithermal neutrons, and the output end of the FPGA processor is connected to a logging computer in a communication mode and is used for uploading the counting information so as to calculate uranium content of a stratum.
7. The method of using a dual neutron logging tool integrated in situ according to claim 5, comprising the steps of: In the same thermal neutron field, calibrating the first scintillation crystal and the second scintillation crystal, calculating the ratio of thermal neutron detection efficiency between the crystals, and further determining the ratio of the first scintillation crystal to the epithermal neutron detection efficiency and the second scintillation crystal to the thermal neutron detection efficiency; Starting a pulse neutron source to emit neutrons, and collecting pulse signals of thermal neutrons, epithermal neutrons and gamma rays based on a spatial structure read out by a common optical path of the detection part; based on a pulse waveform discrimination algorithm, the acquired pulse signals of thermal neutrons, epithermal neutrons and gamma rays are discriminated in real time, the pulse signals of the thermal neutrons and the epithermal neutrons are recorded, the pulse signals of the gamma rays are removed, a thermal neutron time spectrum and an epithermal neutron time spectrum are obtained, and thermal neutron count and epithermal neutron count are counted respectively; Outputting the flux ratio of the epithermal neutrons to the thermal neutrons according to the ratio of the epithermal neutron detection efficiency of the first scintillation crystal to the thermal neutron detection efficiency of the second scintillation crystal, the counted epithermal neutron count and the counted thermal neutron count; and calculating the uranium content of the stratum according to the flux ratio of the epithermal neutrons to the thermal neutrons.
8. The method of claim 7, wherein the ratio of thermal neutron detection efficiencies between the crystals is equal to the ratio of the first scintillation crystal to the epithermal neutron detection efficiency to the second scintillation crystal to the thermal neutron detection efficiency.

Description

Double neutron detector integrated in same position, logging instrument and application method Technical Field The invention relates to the technical field of uranium mine exploration logging, in particular to a double neutron detector integrated in a position, a logging instrument and an application method. Background The traditional pulse neutron uranium ore logging instrument needs to be provided with a thermal neutron detector and an epithermal neutron detector in an axial separation mode, such as a gas detector adopting a 3He tube, is limited by the size of a borehole, the diameter of the borehole is generally smaller than 60mm, the distance between the epithermal neutron detector and the thermal neutron detector is generally larger, and due to dynamic change of the distribution of stratum thermal neutrons along a well axis along time, the neutron flux of the epithermal neutron detector cannot be truly reflected by the thermal neutron count due to the separation design of the epithermal neutron detector and the thermal neutron detector, and a space inconsistency error is introduced. In the prior art, china patent CN203515572U discloses a uranium fission prompt neutron logging instrument based on the ratio of epithermal neutrons to thermal neutrons, the scheme discloses that a double neutron detector and a double neutron time spectrometer in the logging instrument comprise two groups of proportional counting tubes, a polyethylene neutron moderating material wrapping the epithermal neutron detector, a metal cadmium skin wrapping the moderating material, a detector high-voltage power supply, a pre-amplifier, a shaping and discriminating circuit, a pulse counter for recording output signals of the double neutron detector and a time spectrum analyzing and buffering circuit, wherein the double neutron detector adopts a plum blossom structure, namely the epithermal neutron detector is positioned at the center of the cross section of a probe tube, a plurality of small-volume thermal neutron detectors are positioned around the epithermal neutron detector, gaps between the double neutron detectors are filled with medium with very high hydrogen content and are in the moderating material, plum blossom-shaped contours are formed, so that the two neutron detectors are almost positioned at the same axial position, and the design of the double neutron detector has the least influence on thermal neutron calculation correction factors, namely the introduced errors. The improvement scheme can improve the detection precision by reducing the position difference of the epithermal neutron detector and the thermal neutron detector, but the detector has larger overall structure size and is inconvenient to apply in a small-size well hole on one hand, and has limited detection precision in counting thermal neutrons due to the fact that the distance exists between the epithermal neutron detector and the thermal neutron detector due to the design of the installation position between the epithermal neutron detector and the thermal neutron detector on the other hand, and in addition, the detector group needs seven paths of read-out electronic channels altogether, so that the hardware structure is complex. Therefore, with the exploration of new materials and the current higher requirements on the precision of the detector, new structural designs of the dual neutron detector in the logging instrument are needed to meet the application requirements. Disclosure of Invention 1. Technical problem to be solved by the invention The invention aims to overcome the defect that in the prior art, a uranium ore logging instrument needs to be provided with a thermal neutron detector and a epithermal neutron detector in an axial separation way, so that the final thermal neutron count cannot truly reflect the neutron flux of the position of the epithermal neutron detector, and a space inconsistency error is introduced. 2. Technical proposal In order to achieve the above purpose, the technical scheme provided by the invention is as follows: The invention provides a double neutron detector integrated at the same position, which comprises a first scintillation crystal, a second scintillation crystal, a photoelectric converter and a supporting part, wherein the first scintillation crystal and the second scintillation crystal are crystals sensitive to thermal neutrons; the second scintillation crystal forms a thermal neutron detection unit, the thermal neutron detection unit and the thermal neutron detection unit are arranged in a surface-to-surface joint way, the photoelectric converter is arranged on the end face, far away from the thermal neutron detection unit, of the thermal neutron detection unit in a coupling way, and the thermal neutron detection unit, the thermal neutron detection unit and the photoelectric converter form a detection part for reading out a common optical path along the same axial direction; The supporting part is fixedly arrange