Development of monoenergetic energy neutron generating target for irradiation of biological materials using an accelerator and its dosimetry

该研究包括：(1)用于放射生物学研究的单能中子产生系统的开发（特别是中子产生靶的开发）；(2)中子的剂量学研究。实际的研究是：(a)开发和确认了在铜板上蒸发金属锂的技术，并将其用作厚度约为10 μ m的薄锂靶；(b)使用双室法测量（n, p）反应产生的中子剂量率；(c)分别使用LET计数器和Hc-3中介仪测量中子的质量和光谱。(d)测定靶体的稳定性（可能的照射时间）和(e)小鼠试验照射以检查总照射系统。对于测量(b)，我们使用组织等效室来测定中子加伽马射线的总剂量，石墨室和GM计数器来测定伽马射线剂量。在(a)的研究中，我们使用蒸发装置制作了约10mum厚的锂靶。现在我们可以常规地制作它们。对于(b)，我们确定了不同角度和距离下的剂量率。剂量率可达10cgy /min以上，γ射线污染小于5%。(c)单能中子的能量分布为5-9%。我们发现LET光谱再现了其他测量值。在(b)中，我们发现大约10小时的照射是可能的。在(e)中，我们检查了整个辐照系统工作合理。总之，我们证实了该中子辐照系统可用于放射生物学研究，并成功地完成了本研究。在此之后，有必要开发其他类型的目标并建立PIXE系统。

This study included that (1) development of monoenergetic energy neutron generating system for use in radiobiology study (especially development of neutron generating targets), (2) dosimetry study of the neutrons.The actual studies were (a) development and confirmation of a technique to evaporate lithium metal on copper plate and to use as thin lithium target of about 10 mum thickness, (b) measurement of neutron dose rate generating due to (n, p) reaction using twin chamber method, (c) measurement of quality and spectra of the neutrons using LET counters and Hc-3 neutron spectrometer, respectively, (d) measurement of stableness of the target (possible irradiation time) and (e) test irradiation of mice to check total irradiation system. As for the measurement (b) we used a tissue equivalent chamber for determination of total neutron plus gamma-ray doses, and graphite chamber and GM counter for determination of gamma-ray dose.In the study of (a) we used a evaporation apparatus and made about 10mum thick lithium target. Now we can make them routinely. As for (b) we determined dose rates at different angles and distances.The dose rate more than 10 cGy/min is available and contamination of gamma rays are less than 5%. In(c)energy spread of monoenergy neutrons are 5-9%. We found the LET spectrum reproduced the other measurements. In (b), we found irradiation for about 10 hours are possible. In (e), we checked the total irradiation system was working reasonably.In conclusion we confirmed this neutron irradiation system for radiobiology study and successfully completed this study. After this, it will be neccessary that development of the other types of targets and set up of the PIXE system.