Multidimensional positron annihilation lifetime spectrum and doppler broadening spectrum measurement systems

Abstract

The invention discloses a multidimensional positron annihilation lifetime spectrum and doppler broadening spectrum measurement systems. Each of the multidimensional positron annihilation lifetime spectrum measurement system and the doppler broadening spectrum measurement system comprises an anticoincidence system and a three-dimensional moving system. Each anticoincidence system comprises a positron detector, a first preamplifier, a first spectrum amplifier, a first single-channel analyzer and a coincidence device, which are sequentially connected; each positron detector consists of a flicker flake and a photomultiplier tube, which are coupled through silicone oil, and a radioactive source is an isotope radioactive source, and is directly dropped on the flicker flake; the three-dimensional moving systems are used for loading a sample and moving the sample in a three-dimensional direction. According to the system, annihilation information not belonging to the sample is eliminated by adopting the anticoincidence systems, so that the detection reliability and the detection accuracy can be improved; the distances and the directions between the sample and the positron detectors are regulated by adopting three-dimensional moving platforms, so that multidimensional, accurate and nondestructive defect detection of a single irregular sample can be realized.

Description

technical field [0001] The invention relates to a positron annihilation lifetime spectrum and Doppler broadening spectrum measurement system capable of detecting multi-dimensional defects. Background technique [0002] Positron spectroscopy uses positrons as probes to study the interaction between positrons and matter, and uses modern nuclear spectroscopy methods to accurately measure annihilation parameters, thereby obtaining useful information about the microstructure of matter. As a nondestructive testing technique, conventional positron annihilation techniques include positron annihilation lifetime spectroscopy and Doppler broadening spectroscopy. positron emitting source 22 The gamma photon with energy of 1.28 MeV emitted by Na is used as the start signal of the positron, and the gamma photon with the energy of 0.511 MeV emitted after the annihilation of the positron in the sample is used as the termination signal of the positron, and the interval between the start sig...

AI Technical Summary

Problems solved by technology

In actual application sites, the use of current conventional detection methods only detects whether the outer surface of the material is damaged, but the condition of the inner surface of the material is difficult to detect

Although positron annihilation spectroscopy can detect material defects sensitively, the current conventional positron annihilation spectrometer can only detect materials with smooth and complete surfaces and cannot detect samples with irregular shapes.

Positron annihilation lifetime spectroscopy and Doppler broadening spectrum measurement systems mostly use a "sandwich" sandwich structure, that is, two identical samples are used to sandwich the radioactive source for measurement. Strictly speaking, it is not a true non-destructive testing (NDT). There are the following shortcomings in the application: (1) Due to this "sandwich" sandwich structure, the sample is in direct contact with the radioactive source, which may easily lead to damage to the radioactive source and contamination of the sample by radioactive material leakage, and it is not easy to realize the real-time measurement of the sample environment Changes in (light, magnetic field, temperature, etc.)

(2) This "sandwich" sandwich structure cannot realize defect detection of large samples and thick samples, nor can it realize in the field detection

(3) The samples used in the "sandwich" sandwich structure are usually two identical two-dimensional planar structures, which cannot achieve accurate non-destructive testing of multi-dimensional defects in a single irregular sample

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