Constructing energy spectrum of inorganic scintillator based on plastic scintillator by different kernel functions of SVM learning algorithm and TSC data mapping

Abstract

In this paper, a novel idea is developed to construct energy spectrum of inorganic scintillator detector (e.g. NaI(Tl)) using energy spectrum of organic scintillator detector (e.g. NE102) by means of a model-free method. For this purpose, support vector machine (SVM) accompanied with different kernel functions (i.e. linear, polynomial, and Gaussian) is applied. The spectra of NE102 and NaI(Tl) detectors of the single radioisotopes (i.e. Co60, Cs137, Na22, and Am241) are utilized for training of SVM. In other words, data of NE102 detector are input spectrums of training patterns and data of NaI(Tl) detector are target spectrums of training patterns. To construct an appropriate mapping function between spectrums of detectors, a kind of cross-correlation technique namely mapping of totality of channels to single channel (TSC) is utilized. In the test process, spectrums of different combinations of the target radioisotopes are constructed and the results are compared with the measured spectrums. Polynomial kernel function gives good results. Linear and Gaussian kernel functions do not give so appropriate results. The major advantages of the developed method are: 1- The NaI(Tl) spectrums of different combinations of the target radioisotopes are constructed only by training of single radioisotopes spectrums. 2- Energy spectrums of high price/ high resolution detectors (i.e. inorganic scintillator detectors) can be constructed using low price/ low resolution detectors (i.e. plastic scintillator detectors). 3- This method can be used to construct energy spectrum of any type of inorganic scintillator (e.g. BGO detector) using either plastic or liquid scintillators. Liquid scintillator detectors (e.g. NE213) are more appropriate for detection/identification of radioactive sources which emit both gamma and neutron radiations. However, these detectors give low resolution gamma spectrums. The developed method can be appropriate for construction of higher resolution gamma spectrums for this type of sources. This application of the developed method is discussed in the manuscript.