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精确的质量测量。对这种测量的兴趣在于它们与使原子核结合在一起的核力之间的直接关系，从而决定了原子核的结构。这些力是如此之强，以至于它们给原子核的结合能大大降低了原子核的质量。放射性的，即不稳定的原子核特别有趣，因为原子核越不稳定，使它结合在一起的核力的强弱就越明显。然而，短寿命放射性原子核的质量测量本身就比测量地球上存在的正常、稳定的原子要困难得多。这不仅是因为处理放射性有困难，更重要的是，因为原子核寿命很短，只有在能够产生它们的高能加速器设施中才能得到，而且即使在那里，也只能产生非常少量的原子核。这里提出的研究计划使用了一种基于电磁陷阱的新型高精度高灵敏度质谱仪，该质谱仪是由麦吉尔大学与欧洲科学家合作开发的。第一个这样的仪器被命名为ISOLTRAP，是为欧洲核子研究中心的ISOLDE放射性束流设施开发的。到目前为止，这台仪器已经测量了200多个放射性原子核，最短的半衰期为85毫秒。它还导致在世界各地建造了5个类似的光谱仪，新一代这样的光谱仪是TRIUMF ISAC泰坦设施的重要组成部分。本研究计划的一个重要部分是研制能有效地将放射性离子送入质谱仪的装置。这项拨款申请是为了进一步发展这种装置，特别是在缓冲气体中使用高频四极电场来操纵微型结构中的离子。这些技术不仅在核物理学中有应用，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.