Development: A Single-Ion Penning Trap Mass Spectrometer (SIPT) for Very Rare Isotopes Produced via Projectile Fragmentation

高精度的彭宁阱质谱仪已经在世界各地的几个稀有同位素设施中开发出来，因为它在确定原子核的基本性质——质量方面具有非凡的精度和准确性。彭宁阱质谱仪通过测量带电粒子在强磁场中的回旋频率来确定带电粒子的质量。目前，用于稀有同位素的Penning阱质谱计采用飞行时间离子回旋共振（TOF-ICR）检测方案，该方案是通用的，但通常需要每小时至少几个离子的稀有同位素离子速率。为了克服这种灵敏度限制，该小组将开发、建造和安装专用的单离子Penning陷阱光谱仪（SIPT）质谱仪，该质谱仪使用超导螺螺管提供的6特斯拉磁场，并采用窄带傅立叶变换离子回旋共振（FT-ICR）方法。该技术将被优化，以研究非常罕见的同位素，仅以非常低的速率提供，每天或每周一次，这种速率禁止使用TOF-ICR技术。窄带FT-ICR方法使用一个调谐的超导电路来放大彭宁阱电极上单个带电粒子在阱内移动时产生的信号。通过对放大后的信号进行傅里叶分析，可以确定回旋加速器的频率。由于窄带FT-ICR不像TOF-ICR那样普遍，因此它最适合用于传输率极低且具有重大科学意义的候选者。拟议的SIPT质谱仪将具有广泛的意义和重要性，因为它提高了我们确定稀有同位素的质量的能力，这些同位素的中子和质子数量的比例非常不同于在地球上发现的稳定同位素。测定这些奇异的、通常寿命很短的稀有同位素的质量是极其重要的，因为它提供了中子和质子在原子核中被束缚的紧密程度的直接信息。大量的稀有同位素作为输入数据用于各种科学领域，如核结构、核天体物理学和基本相互作用。例如，稀有同位素在恒星环境中大量产生，在恒星演化中起着关键作用，但在地球上的稀有同位素束流设施中产生非常具有挑战性，对于许多重要的同位素，束流率非常低。SIPT的高灵敏度技术将能够仅用一种稀有同位素离子进行质量测量，将稀有同位素的精确质量测量推向更多外来同位素的前沿。这项技术的发展也将有利于未来在稀有同位素光束设施（FRIB）的使用。我们相信，SIPT项目的跨学科性质非常适合吸引和教育来自代表性不足的群体的学生，从而使每个人都有更强的研究计划和更强的文化意识。

High-precision Penning trap mass spectrometers have been developed at several rare-isotope facilities around the world due to the extraordinary precision and accuracy that has been demonstrated in determining a fundamental property of a nucleus, its mass. Penning trap mass spectrometers determine the mass of a charged particle via a measurement of its cyclotron frequency in a strong magnetic field. At present, Penning trap mass spectrometers for rare isotopes employ a time-of-flight ion cyclotron resonance (TOF-ICR) detection scheme which is universal but typically requires at minimum rate of rare isotope ions of at least a few ions per hour. In order to overcome this sensitivity limit the group will develop, build, and install a dedicated Single Ion Penning Trap Spectrometer (SIPT) mass spectrometer using a 6 Tesla magnetic field provided by a superconducting solenoid and employing the narrowband Fourier Transform Ion Cyclotron Resonance (FT-ICR) method. The technique will be optimized for the study of very rare isotopes provided only at very low rates, one per day or week, a rate that prohibits the use of the TOF-ICR technique. The narrowband FT-ICR method uses a tuned, superconducting circuit to amplify the signal generated by a single charged particle on the electrodes of the Penning trap as it moves around inside the trap. By performing a Fourier analysis on the amplified signal, the cyclotron frequency can be determined. As narrowband FT-ICR is not as universal as TOF-ICR, it is best used on candidates with extremely low delivery rates and of great scientific interest.The proposed SIPT mass spectrometer will have a broad significance and importance by improving our ability to determine the mass of rare isotopes with unusual ratios of the number of neutrons and protons, much different from those found in stable isotopes, as they exist on Earth. The determination of the masses of such exotic and often very short-lived rare isotopes is of utmost importance since it provides direct information on how tightly the neutrons and protons are bound in the atomic nucleus. Masses of rare isotopes serve as input data in a variety of fields of science, such as nuclear structure, nuclear astrophysics, and fundamental interactions. For example, rare isotopes are produced in abundance in stellar environments and play a key role in the star's evolution but the production on earth in rare isotope beam facilities is very challenging, and for many important isotopes the beam rates are very low. SIPT's highly sensitive technique will be capable of making a mass measurement with only a single rare isotope ion, pushing the frontier of precision mass measurements of rare isotopes to more exotic isotopes. The development of this technology will also be of benefit for future use at the Facility for Rare Isotope Beams (FRIB). We believe that the interdisciplinary nature of the SIPT project is well suited for attracting and educating students from underrepresented groups, resulting in a stronger research program and greater cultural awareness for everyone involved.