分类: 物理学 >> 核物理学 提交时间: 2024-06-25
摘要: In conventional isochronous mass spectrometry (IMS) performed at a storage ring, the precision of mass measurement for short-lived nuclei depends on the precise determination of the revolution times (Ts) of stored ions. However, the resolution of T inevitably deteriorates due to the magnetic rigidity spread of the ions, resulting in limited mass resolving power. In this work, we measure the betatron tune Q (the number of betatron oscillations within a single revolution) of the ions, and construct a correlation between T and Q. From this correlation, the T are transformed corresponding to a fixed Q with higher resolution. Using the transformed Ts, we re-determine the masses of 63Ge, 65As, 67Se, and 71Kr, which agree well with the mass values measured by the newly developed IMS (Bρ-IMS). We also study the systematics of Coulomb displacement energies (CDEs) and find that the anomalous staggering in CDEs is removed using the new mass values. This method of T transformation is very useful for the conventional IMS equipped with a single time-of-flight detector.
分类: 物理学 >> 核物理学 提交时间: 2023-06-24
摘要: The multinucleon transfer (MNT) reaction is one promising way to produce neutron-rich heavy nuclei and even super heavynuclei and attracts more and more attentions theoretically and experimentally. A low energy nuclear structure spectrometer calledLENSHIAF specific to the MNT reactions will be designed and constructed in the ongoing big project HIAF in China. In theLENSHIAF spectrometer, the most challenge part is how to collect and stop efficiently the high-energy MNT products into the gascell. By using Monte-Carlo method, the geometry of the gas cell, the thickness of the titanium window/degrader, and the optimalgas pressure filled in the gas cell have been calculated and estimated. For neutron-rich nuclei around N=126 from 136Xe+198Ptreaction, with a titanium window/degrader with a thickness of 2.53.5 um, a cylindrical helium gas cell with a length of 0.6 m and adiameter of 1.2 m can satisfy the requirements to stop the target-like fragments. For heavier and super heavy nuclei from 238U+238Ureaction, with a 58 um thick titanium window/degrader, the cylindrical gas cell has to be as big as a length of at least 1.6 m and adiameter of 1.6 m.