EMMA, the ISAC-II Recoil Mass Spectrometer

EMMA，ISAC-II 反冲质谱仪

• 批准号: SAPPJ-2016-00031
• 负责人: Davids, Barry
• 金额: $ 8.01万
• 依托单位: TRIUMF
• 依托单位国家: 加拿大
• 项目类别: Subatomic Physics Envelope - Project
• 财政年份: 2018
• 资助国家: 加拿大
• 起止时间: 2018-01-01 至 2019-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=648714
• 关键词: EMMA; ISAC; II; Recoil; Mass

EMMA (ElectroMagnetic Mass Analyser) is a recoil mass spectrometer for TRIUMF's ISAC-II facility. ISAC-II provides intense beams of radioactive ions with masses up to 150 atomic mass units to international scientists studying nuclear structure and nuclear astrophysics at Canada's national subatomic physics lab. The energies of these beams depend on the specific nuclei being accelerated, but typical top speeds range from 10-20% of the speed of light. At these energies, different types of nuclear reactions can be studied to learn about the structure of exotic nuclei and the nuclear reactions that produce the chemical elements in stars and stellar explosions. In order to learn about the properties of these nuclei and measure the rates of reactions that produce the chemical elements in stars, it is first necessary to identify the products of these reactions. An atomic nucleus can be uniquely identified by measuring its charge and its mass. The charge of a nucleus is simply the number of protons it contains, while its mass is the sum of the number of neutrons and protons that make it up.***How can one measure the mass and charge of a nucleus? The trajectories of nuclei in magnetic fields are bent according to their momentum and charge, while in electric fields the trajectories depend on the energy and charge of the nucleus. By combining electric and magnetic fields in a particular way, one can cancel the energy and momentum dependence of the trajectories, and bend them according to their masses and charges alone. Hence a device that combines electric and magnetic fields can be used to separate an interesting nucleus produced in a nuclear reaction from all of the other nuclei produced in different nuclear reactions and from the beam used to initiate the reactions. Such a device is called a recoil mass spectrometer, because it analyzes the products of nuclear reactions, called recoils, dispersing them according to their mass and charge. Once complete, EMMA will be used in approximately 1/3 of the experiments at ISAC-II.**

EMMA（电磁质量分析仪）是TRIUMF ISAC-II设施的反冲质谱仪。ISAC-II为在加拿大国家亚原子物理实验室研究核结构和核天体物理学的国际科学家提供质量高达150原子质量单位的强放射性离子束。这些光束的能量取决于被加速的特定原子核，但典型的最高速度范围为光速的10-20%。在这些能量下，可以研究不同类型的核反应，以了解奇异核的结构以及在恒星和恒星爆炸中产生化学元素的核反应。为了了解这些原子核的性质，并测量在恒星中产生化学元素的反应速率，首先需要确定这些反应的产物。一个原子核可以通过测量它的电荷和质量来唯一地识别。原子核的电荷就是它所包含的质子数，而它的质量就是组成它的中子和质子数的总和。如何测量原子核的质量和电荷？原子核在磁场中的运动轨迹根据其动量和电荷而弯曲，而在电场中，运动轨迹取决于原子核的能量和电荷。通过将电场和磁场以特定的方式结合，人们可以消除轨道的能量和动量依赖性，并且仅根据它们的质量和电荷使它们弯曲。因此，一个结合电场和磁场的装置可以用来将核反应中产生的感兴趣的原子核与不同核反应中产生的所有其他原子核以及用于引发反应的束分离。这种装置被称为反冲质谱仪，因为它分析核反应的产物，称为反冲，根据它们的质量和电荷分散它们。一旦完成，EMMA将用于ISAC-II的大约1/3的实验。