Biju K, Sunil C, Sarkar P K
Health Physics Division, Bhabha Atomic Research Centre, Mumbai 400085, India.
Radiat Prot Dosimetry. 2013 Dec;157(3):437-41. doi: 10.1093/rpd/nct148. Epub 2013 Jun 10.
The FLUKA Monte Carlo simulations are carried out to estimate the (41)Ar concentration inside accelerator vaults of various sizes when proton beams of energy 0.1-1.0 GeV are incident on thick copper and lead targets. Generally (41)Ar concentration is estimated using an empirical formula suggested in the NCRP 144, which assumes the activation is caused only by thermal neutrons alone. It is found that while the analytical and Monte Carlo techniques give similar results for the thermal neutron fluence inside the vault, the (41)Ar concentration is under-predicted by the empirical formula. It is also found that the thermal neutrons contribute ∼41 % to the total (41)Ar production while 56 % production is caused by neutrons between 0.025 and 1 eV. A modified factor is suggested for the use in the empirical expression to estimate the (41)Ar activity 0.1-1.0-GeV proton accelerator enclosures.
开展了FLUKA蒙特卡罗模拟，以估算当能量为0.1 - 1.0 GeV的质子束入射到厚铜靶和铅靶上时，各种尺寸加速器防护室内的（41）氩浓度。通常，（41）氩浓度是使用NCRP 144中建议的经验公式估算的，该公式假定活化仅由热中子单独引起。结果发现，虽然分析技术和蒙特卡罗技术对于防护室内热中子注量给出了相似的结果，但经验公式对（41）氩浓度的预测偏低。还发现热中子对总（41）氩生成的贡献约为41%，而56%的生成是由能量在0.025至1 eV之间的中子引起的。建议在经验表达式中使用一个修正因子来估算0.1 - 1.0 GeV质子加速器防护室内的（41）氩活度。
