Nuclear mass measurements and ion manipulation

这一应用是为了继续支持对短寿命放射性核进行极高精度的质量测量。人们对这种测量的兴趣在于它们与将原子核保持在一起的核力直接相关，从而确定了原子核的结构。这些力是如此强大，以至于它们赋予原子核的结合能使其质量降低了可测量的量。放射性原子核，即不稳定的原子核特别有趣，因为一个原子核越不稳定，将其结合在一起的核力的优势和弱点就越明显。然而，对短寿命放射性核的质量测量天生就比对地球上存在的正常、稳定的原子的测量困难得多。这不仅是因为处理放射性的困难，更重要的是因为这些核很短暂，只能在能够产生它们的高能加速器设施中获得，而且即使在那里，也只能获得非常少量的核。这里提出的研究计划使用了一种新型的基于电磁陷阱的高精度高灵敏度质谱仪，该仪器是由麦吉尔与欧洲科学家合作开发的。第一台这样的仪器名为ISOLTRAP，是为欧洲核子研究中心的Isolde辐射束设施开发的。该仪器迄今已允许对200多个放射性原子核进行测量，最短的半衰期为85毫秒。此外，它还导致在世界各地建造了5台类似的光谱仪，新一代这样的光谱仪是国际SAC在TRIUMF的泰坦设施的重要组成部分。这项研究计划的一个重要部分是开发能够有效地将放射性离子送入质谱仪的设备。这项拨款申请是为了进一步开发这种设备，特别是使用缓冲气体中的高射频四极电场来操纵微型结构中的离子。这种技术不仅在核物理中有应用，而且在生物分子研究和纳米科学中也有应用。

This application is for continued support of extreme accuracy mass measurements on short-lived radioactive nuclei.  The interest in such measurements is in their direct relationship to the nuclear forces that hold nuclei together, thereby determining the structure of the nuclei. These forces are so strong that the binding energy they give to a nucleus lowers its mass by a measurable amount.  Radioactive, i.e. unstable, nuclei are particularly interesting because the more unstable a nucleus the more obvious are the strengths, and weaknesses, of the nuclear forces in holding it together. However, mass measurements of short-lived radioactive nuclei are inherently much more difficult than measurements of normal, stable atoms such as exist on Earth.  This is not only because of difficulties in dealing with radioactivity but, more importantly, because the nuclei are short-lived and available only at the high-energy accelerator facilities that can produce them and, even there, only in very minute quantities. The research program proposed here uses a novel form of high-precision high-sensitivity mass spectrometer based on electromagnetic traps that has been developed by a McGill collaboration with European scientists. The first such instrument, named ISOLTRAP, was developed for the ISOLDE radioactive beam facility at CERN.  This instrument has to date allowed measurements on over 200 radioactive nuclei, the shortest half-life being 85 milliseconds.  It has also led to the construction of 5 similar spectrometers around the world, with a new generation of such a spectrometer being an essential part of the TITAN facility of ISAC at TRIUMF. An essential part of this research program is the development of apparatus to manipulate the radioactive ions efficiently into the mass spectrometer. This grant application is for further development of such apparatus, particularly using high radiofrequency quadrupole electric fields in buffer gas to manipulate the ions in miniature structures. Such techniques not only have applications in nuclear physics but also in biomolecular research and nanoscience.