The Research Of Optimizing Detection Method Of Proportional Counter To Tritium Based On Geant4

Tritium is a type of radionuclide and it is able to release ? particles with low energy,basically tritium is becoming one of the most significant elements in the development of nuclear industry.In the process of being used by human,various wasted and tritiated gases and liquids were released into the air,which posed a huge threat to the health of atmosphere and human.In order to guarantee the safty of staff who work in the atmosphere containing tritium,the content of tritium in working environment must be detected accurately.Currently,there are many ways measuring ? particles,such as liquid scintillators,ionization chambers and ?-ray induced X-ray spectrometry.Actually,liquid scintillators and ionization chambers have the highest frequency in detection,and it will be a better choice to use proportional counter when measuring ? particles released by tritium.However,proportional counter involves many parameters(anode's radius,cathode's radius,medium gas,chamber pressure and high voltage),it will be tough and difficult to obtain a better experiment result when choosing in-real detection.This paper took formula computing and finally obtained criteria that can make sure the reasonable structure of proportional counter,and also the parameter ranges of proportional counter's optimal structure were listed.In addition,this paper selected Geant4 as a tool to simulate the probabilities of ? particles released by tritium drifted into avalanche area in cylindrical proportional counter.By adjusting three parameters of anode's radius,voltage and gas pressure in proportional counter,probabilities in different conditions were obtained,eventually the better physical parameters which help proportional counter to acquire the probabilities of ? particles released by tritium drifted into avalanche area.The programme in this paper only recorded “seed electrons” that triggered avalanche effect.In the condition of making sure the number of ? particles from tritium,the amount of ? particles that triggered avalanche effect in different energy ranges and then the tendency of detection results of different ? particles with various energies of proportional counter under some specific parameters was obtained.Finally by calculating the regularity of average detection results of tritium measured by proportional counter in different physical conditions mentioned above,the tendency of tritium detection of proportional counter was obtained as well as the optimized methods.The mainly works were completed in this paper are as follows:(1)Built the model of proportional counterBy taking empirical formula to make sure the reasonable structure parameters of proportional counter and using Geant4 to build the model of proportional counter including the size of detector,the type of electric field and the design of sensitive area in proportional counter.This model truly catered for the structure and size of real proportional counter and set adjustable parameters(value of anode's radius,gas pressure and high voltage)to guarantee the facticity of simulations.(2)Simulation and calculationIn the model of detector created with Geant4,different energy ranges of ? particles from tritium were simulated and the number of ? particles that was able to trigger avalanche effect in each single simulation was recorded.And then the results were transferred into the tendency of detection results of gaseous tritium,finally the regularity of detection results caused by different physical parameters was obtained.(3)Analysis of optimized methodsBased on the regularities of simulations,a series of optimized methods were obtained.The creative points in this paper are as follows:(1)By researching and analyzing references,some empirical formulas were taken to list the ranges of various parameters that are able to make sure proportional counter be workable.(2)This programme avoided the tough and difficult avalanche process and only recorded the number of “seed electrons” that triggered avalanche effect,and eventually the tendency of detection results to gaseous tritium by proportional counter was obtained as well as the optimized methods.According to simulation and analysis in this paper,the reasonable proportion of size of both anode and cathode and also the regularity among anode's radius,voltage,pressure and tendency of detection results for gaseous tritium was obtained as well as their connections,which could make sense in developing proportional counter and in tritium detection.