Gamma Rays In The Plastic - Nai (t1) In Composite Detector Response Function And Detection Efficiency Of Monte Carlo Simulation

In the use of high resolution, high detection efficiency and the lowestpossible background gamma spectrometer for accurate analysis of low levelradionuclide content in environmental samples，in order to improve thegamma energy spectrum measuring sensitivity and precision, general withanticoincidence shielded. Anticoincidence shielded ring can choose NaI (Tl)crystals and plastic (including liquid) scintillator.With the electronic cascade complex physical mechanisms and generatesecondary particles in the reaction process of Physics Statistical properties, inaddition many regions geometry medium with complex boundary conditions,so in the anticoincidence shielded gamma spectrometer simulated by commonmathematical methods such as numerical calculation method is incapable ofaction,while the Monte Carlo method can directly from the objective physicalproblems, In less approximation can realistically simulate the physical processof development. The method also has the very strong handle the complexgeometry and section capacity. That is to say the Monte Carlo method canovercome the above two aspects of difficulties to become an effective tool tocalculate this kind of problem.According to the manufacturers to provide parameters to establish theinitial physical model, Simulation of plastic crystal NaI (Tl) detector energyresponse and detection efficiency of experimental measurements of theexperimental environment and conditions, In the simulation processconsidering the Compton scattering suppression performance effect, Thecalculation results and experimental results were analyzed, Further analysis ofgamma response function. Study of plastic crystal NaI (Tl) detector for pointsource and source of energy when changing the response function andcomposite detector plastic crystal with NaI (Tl) crystal size and proportion ofgamma response function influence, composite detector plastic crystal withNaI (Tl) crystal single crystal size as well as composite size and detectionefficiency of the relationship between. Finally, using VC++programmingand MCNP calculation, the plastic-NaI (Tl) composite detector responsefunction and calculate the detection efficiency, By statistically processingsoftware to realize the detection efficiency curve fitting.