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

开发：单离子潘宁阱质谱仪 (SIPT)，用于分析弹丸碎片产生的非常稀有同位素

• 批准号: 1126282
• 负责人: Georg Bollen
• 金额: $ 58.56万
• 依托单位: Michigan State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-09-15 至 2016-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1126282&HistoricalAwards=false
• 关键词: Development; Single; Ion; Penning; Trap

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.

高精度的彭宁陷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，这是因为在确定原子核的基本性质--它的质量--方面表现出了非凡的精确度和准确度。彭宁陷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其质量。目前，用于稀有同位素的Penning陷阱质谱仪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，但通常要求稀有同位素离子的最低速率至少为每小时几个离子。为了克服这一灵敏度限制，该小组将开发、建造和安装专用的单离子彭宁陷阱质谱仪(SIPT)，该质谱仪使用超导螺线管提供的6特斯拉磁场，并采用窄带傅里叶变换离子回旋共振(FT-ICR)方法。这项技术将被优化，以研究仅以非常低的速率提供的非常稀有的同位素，每天或每周一次，这一速率禁止使用TOF-ICR技术。窄带FT-ICR方法使用一个可调谐的超导电路，当单个带电粒子在彭宁陷阱内移动时，放大它在电极上产生的信号。通过对放大信号进行傅里叶分析，可以确定回旋频率。由于窄带FT-ICR不像TOF-ICR那样通用，因此它最适合于投递率极低和具有重大科学价值的候选者。建议的SIPT质谱仪将具有广泛的意义和重要性，它将提高我们测定稀有同位素的质量的能力，这些稀有同位素的中子和质子数量比例与地球上存在的稳定同位素有很大不同。确定这种稀有的稀有同位素的质量是极其重要的，因为它提供了关于中子和质子在原子核中结合得有多紧密的直接信息。大量稀有同位素作为各种科学领域的输入数据，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，并在恒星的演化中发挥关键作用，但在地球上使用稀有同位素束流设施进行生产非常具有挑战性，而且对许多重要的同位素来说，束流速率非常低。SIPT的高灵敏度技术将能够只用一个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的前沿推向更稀有的同位素。这项技术的发展也将有利于今后在稀有同位素束设施(FRIB)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群体的学生，从而为参与其中的每个人带来更强大的研究计划和更高的文化意识。