Two-dimensional beam profile monitor for the detection of alpha-emitting radioactive isotope beam
Two-dimensional beam profile monitor for the detection of alpha-emitting radioactive isotope beam
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用于检测α发射放射性同位素束的二维束流轮廓监测器
DOI：
10.1016/j.nima.2021.165803
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发表时间：
2021
期刊：
影响因子：
--
通讯作者：
Sakemi Y.
中科院分区：
文献类型：
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作者：
Tanaka K.S.;Dammalapati U.;Harada K.;Hayamizu T.;Itoh M.;Kawamura H.;Nagahama H.;Nakamura K.;Ozawa N.;Sakemi Y.
在核设施中，由于核聚变反应产生低能放射性离子，因此无法从现有的束流剖面监测器（BPM）中分离出具有相似荷质比的离子。在这项研究中，我们开发了一个BPM使用的微通道板和电荷耦合器件区分α衰变的放射性同位素从其他离子（反应产物）在核反应中产生的束剖面。该BPM用于优化东北大学回旋加速器和放射性同位素中心（CYRIC）开发的低能量放射性铥离子（Fr+）束，用于使用Fr原子的电子永久电偶极矩（e-EDM）搜索实验。我们证明了BPM的性能分离Fr+束从其他反应产物产生的氧（18 O）束和金（197 Au）靶的核聚变反应过程中。然而，由于Au的质量接近于Fr的质量，因此使用滤质器分离这些元素的离子是一个挑战，并且当使用典型的BPM时，占主导地位的Au+使得Fr+射束轮廓不可见。因此，通过测量Fr同位素的α衰变，我们可以成功地观察到Fr+束和其他离子束。这种监测α发射放射性射束的新技术覆盖了广泛的寿命范围，例如从大约1秒到10分钟，并且可以针对用于医疗应用的其他α发射器射束来实施。
Ions with similar charge-to-mass ratios cannot be separated from existing beam profile monitors (BPMs) in nuclear facilities in which low-energy radioactive ions are produced due to nuclear fusion reactions. In this study, we developed a BPM using a microchannel plate and a charge-coupled device to differentiate the beam profiles of alpha-decaying radioactive isotopes from other ions (reaction products) produced in a nuclear reaction. This BPM was employed to optimize the low-energy radioactive francium ion (Fr+) beam developed at the Cyclotron and Radioisotope Center (CYRIC), Tohoku University, for electron permanent electric dipole moment (e-EDM) search experiments using Fr atoms. We demonstrated the performance of the BPM by separating the Fr+ beam from other reaction products produced during the nuclear fusion reaction of an oxygen (18 O) beam and gold (197 Au) target. However, as the mass of Au is close to that of Fr, separating the ions of these elements using a mass filter is a challenge, and a dominant number of Au+ renders the Fr+ beam profile invisible when using a typical BPM. Therefore, by employing the new BPM, we could successfully observe the Fr+ beam and other ion beams distinctly by measuring the alpha decay of Fr isotopes. This novel technique to monitor the alpha-emitting radioactive beam covers a broad range of lifetimes, for example, from approximately 1 s to 10 min, and can be implemented for other alpha-emitter beams utilized for medical applications.