AB-BNCT中子靶物理设计分析

质子加速器适用于为硼中子俘获治疗提供中子源，其中子源强及能谱较反应堆中子源更具可调性。中子靶物理计算分析是加速器中子源设计的基础，为其提供粒子能量、流强等参数需求分析，并为靶体结构尺寸设计、中子慢化和屏蔽分析等提供前端参数。本文利用MCNPX蒙特卡罗程序，通过对质子打靶的中子产额和能谱、靶体能量沉积、打靶后靶材放射性活度和中子出射空间角分布等进行研究，提出能量2.5 MeV质子轰击100～200 μm锂靶的设计，并用模拟计算数据论证其合理性。该设计中子源在1 mA流强质子轰击下，源强可达9.74×10¹¹ s^-1；拟设计15 mA、2.5 MeV质子束产生的中子源，在治疗过程中靶材放射性活度累积最大值约为1.44×10¹³ Bq。

Analysis of Physical Design for AB-BNCT Neutron Target

Proton accelerator is an appropriate device for providing neutron source for accelerator-based boron neutron capture therapy (AB-BNCT). The intensity and the spectrum of proton accelerator driven neutron source are more adjustable than reactor neutron source. The physical analysis of neutron target is the premise for an accelerator neutron source design, and it gives requirements of the accelerator parameters, like proton energy and beam current. Besides, it also provides parameters for structural design of neutron target and assembles for shaping and shielding. In this paper, Monte Carlo program MCNPX was used. After analyzing neuron yield, neutron spectrum, energy deposition, radioactivity of the target and neutron emitting angle distribution, an optimized design proposal for the AB BNCT neutron source was presented as 2.5 MeV proton beam bombarding with lithium target of 100 μm to 200 μm thickness. The neutron source is designed with an intensity of 9.74×10¹¹ s^-1 from per 1 mA incident proton. And the current of the proton beam is suggested as 15 mA, which will accumulate a radioactivity of the target material within 1.44×10¹³ Bq.