Improve Soil Samples Fired Low Energy γ-ray Measurement Accuracy Of Radionuclide Activity Method

When measure the soil samples radionuclide activity with high puritygermaniumγ-spectrometer for the quantitative analysis, a major factor to affect thelaunch low-energyγ-ray results of radionuclide activity measurement accuracy is theinterference coming from high energy samplesγ-ray Compton scattering. Generallyregardless of the unknownγ-ray energy levels, sample boxes will be filled fully onlywant to increase theγphoton counting by increasing the sample volume to in certainmeasuring time, to reduce measurement error statistics. This loading method isclearly marked to increase the count of high energyγ-ray decathlon, but to the lowenergyγ-ray, the effect is not clear. In contrast, for radionuclide content is to increasefollowing with samples increases, low-energyγ-ray decathlon peak counts ofinterference caused high-energyγ-ray Compton scattering by also will be increased,to impact on the low-energyγ-ray emission radionuclide content measurementaccuracy. Therefore in this paper, measured byγ-ray energy to determine the samplevolume loaded in the box is brought out, to improve measurement accuracy toradionuclides emitting low-energyγray. This loading method is based on thefollowing ideas : As penetration of low-energyγray is weak, a smaller sample loadwill not significantly reduceγ-ray counts in total-energy peak in measurement time,that is not significantly increased statistical measurement error. However, with the samples of decline in the box, the content of the radionuclide emitting high-energyγray will be of proportional reduction, which will cause that the impact of low-energyγ-ray decathlon counting by the high-energyγ-ray Compton scattering will besignificantly reduced. Such loading methods will help to improve the measurementfired low energyγ-ray the accuracy of radionuclide activity.The loading method related withγ-ray energy was studied based on thefollowing two points. Firstly, we will study the relationship between different energyγ-ray decathlon counts in soil samples and loading sample to identify reasonableloading capacity for various-energyγrays. Secondly, by Monte Carlo methods study,the effect with ²³²Th238.6KeV, ²²⁶Ra351.9KeV, 609.3KeV, ¹³⁷Cs661.7KeV fourdifferent-energyγ-ray Compton scattering to ²³⁸U93.4KeV and ²¹⁰Pb46.5KeVdecathlon peak as filling different sample volume in the box, to determine whetherthe decrease of loading sample quatity is conducive to improve the measurementaccuracy.By the study, the reasonable loading capacity of soil samples to different energyγray was obtained as measuring. When lossing some counts in the total-energy peakaccording to the same proportion, low-energyγ-ray loading capacity will bedecreased more than high-energyγray. At the time only few kinds of radioactivenuclides in the soil (e.g. .(232)Th, ²²⁶Ra, ¹³⁷Cs) launchγrays, rays Compton scatteringalso cause ²³⁸U, ²¹⁰Pb and other low-energyγ-ray measurement error of radionuclideactivity will increase with increase of the sample volume. Therefore, measurementmethod according to the energy measuredγray to determine the loading sample didhelp to reduce the high energyγ-ray Compton Scattering interference and improvethe measurement of soil samples fired low energyγ-ray radionuclide content ofaccuracy. Especially at the measurement of ²³⁸U and ²¹⁰pb activities, the effect of thismethod is more clear.