Development Of ?-Ray Thickness Gauge Based On Tellurium Zinc Cadmium Detector

Thickness gauge is one of the commonly used instruments in modern industrial production,and the CdZnTe detector is a kind of semiconductor detector working at room temperature,in order to explore the possibility of its application in low energy?-ray thickness gauge.In this paper,the performance of four detectors of two types was tested and compared with that of HPGe detector and Na I detector.Secondly,MCNP software was used for simulation to obtain the situation of transmission and scattering,when the low energy?-ray hits the different metal with the different angles and different metal thickness.Then,based on the results of simulation,a?-ray thickness gauge was built,the scattering counts of different aluminum film with different thickness at the scattering angle of 135°were measured with the CdZnTe detector,at the same time,the transmission counts were measured with a Na I detector.Finally,a simple on-line thickness gauge was built to verify the performance of thickness gauge based on CdZnTe detector,and its application prospect was analyzed.Specific conclusions are as follows:(1)Among the two kinds of CdZnTe detectors,the performance of the hemispherical CdZnTe detector is generally better than that of the planar CdZnTe detector.The energy resolution of the two kinds of detectors fluctuates steadily with time,the standard deviation is within 0.44%.(2)The simulation results of MCNP show that when the low energy?-ray is incident vertically,to the metal with low atomic number,the backscattering probability shows a good linear relationship with the material thickness.Compared with the material with high atomic number,the low energy?-ray is more suitable for measuring the thickness of the material with small atomic number.(3)When the scattering angle is 135°,The measurement results of aluminum film with different thickness by CdZnTe detector show that the scattering count has a good linear relationship with the aluminum film thickness,the Pearson correlation coefficient is 0.995;The correlation coefficient between the?-ray transmittance count and the thickness of aluminum film is 0.988.(4)The on-line thickness measurement experiment based on the CdZnTe detector shows that the kind of CdZnTe detector we used is not suitable for backscattering on-line measurement,because the sensitive area is small in size and the detection efficiency is low.If the activity of the radioactive source is increased to 10~8 Bq,the CdZnTe detector can achieve on-line transmission measurement,and the sensitivity of the thickness gauge is expected to reach 0.004mm in the range of 0?3 mm.(5)Finally,the possibility and advantages and disadvantages of using CdZnTe detector as on-line measurement of transmission or backscatter are analyzed.