بررسی مکان و راستای آشکارساز جهت مینیمم نمودن ضریب انباشت شار پرتوهای گاما

نویسندگان

دانشگاه صنعتی شاهرود - دانشکده فیزیک

10.22052/4.3.1

چکیده

هدف از این پژوهش گزینش بهترین مکان آشکارساز نسبت به حفاظ و چشمه­ی گاما است که کمترین ضریب انباشت شار فوتون را داشته باشیم. در این کار تحقیقی ضریب انباشت شار پرتوهای گامای چشمه­های سیلندری Cs137، Co60، N16 هم‌محور با حفاظ­هایی از جنس آلومینیوم، آهن و سرب با ضخامت ثابت cm55/1 در آشکارسازCsI(Tl) با استفاده از کد  MCNP-4Cمحاسبه گردید. بدین منظور آشکارساز به ترتیب در فواصل مختلف از 9 الی 18 سانتی­متر و زوایای متفاوت نسبت به محور چشمه از 30 الی 150 درجه قرار گرفت. در این تحقیق سعی بر آن بوده است تا وابستگی ضریب انباشت به عدد اتمی ماده، انرژی پرتو گاما فاصله نسبی آشکارساز- ماده- چشمه و زاویه­ی آشکارساز مورد بررسی قرار گیرد. نتایج به‌دست آمده نشان می­دهد که ضریب انباشت در گستره­ی وسیعی از1 تا 3.5 تغییر می­کند. با توجه به نتایج حاصل از شبیه­سازی­ها، پیشنهاد می­گردد چنانچه هدف کاهش ضریب انباشت باشد لازم است چشمه، حفاظ و آشکارساز هم‌محور باشند. در غیر این صورت هر چه انحراف آشکارساز از محور مرکزی بیشتر باشد ضریب انباشت شار پرتوهای فوتونی در آشکارساز بیشتر می­گردد.

کلیدواژه‌ها


عنوان مقاله [English]

Study the location and the direction of detector in order to minimize the gamma-rays buildup factor

نویسندگان [English]

  • Ali Rasouli
  • Hossein Tavakoli-Anbaran
چکیده [English]

The purpose of this study is to select the best place for the detector towards shield and the gamma source which have the least flux buildup factor of the photon. In this research, the flux buildup factor of gamma rays was calculated by using of MCNP-4C code for cylindrical sources 137Cs, 60Co, 16N coaxial shields made up of aluminum, iron and lead with a constant thickness 1.55 cm in detector CsI (Tl). For this purpose, detector was respectively placed at different distances from 9 to 18 cm and different angles from 30 to 150 degrees with respect to the axis of the source. In this study, we tried to assess the dependency of the buildup factor with material atomic number, gamma-ray energy, relative distance of detector-material-source and angle of detector to source. The obtained results showed that the buildup factor values are variable in a wide range from 1 to 3.5. According to the results of simulation, if the aim is reduction of the buildup factor source, shield and detector should be designed parallel and coaxial. Otherwise, whatever deviation of detector from the central axis is increased, the gamma-rays buildup factors are greater in detector.

کلیدواژه‌ها [English]

  • Flux buildup factor
  • Monte Carlo method
  • Isotopic gamma sources
  • 60 Co
  • 137 Cs
  • 16 N
  • CsI (Tl) detector
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