Gamma-ray spectroscopy on neutron-rich nuclei via RI beam fragmentation method

通过 RI 束碎裂法对富中子核进行伽马射线能谱分析

• 批准号: 13640268
• 负责人: SKAURAI Hiroyashi
• 金额: $ 1.79万
• 依托单位: The University of Tokyo
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2001
• 资助国家: 日本
• 起止时间: 2001 至 2002
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-13640268/
• 关键词: RI beams; profectile fragmentation; neutron-rich nuclei; gamma-ray spectroscopy; stability of nuclei; nuclear collectivity; 破砕反応

The research results obtained in this research project are summarized in the following two points.1.Development of RI beams and discovery of new neutron-rich isotopes.To apply the RI beam fragmentation method for heavier neutron rich nudei with N=28, we developed RI beams by using an intense 48Ca beams, which is appropriate for efficient productions of the nuclei. According to a new acceleration scheme realized at RIKEN, the beam intensity was increased by about two orders of magnitudes. To use the intense beam, we searched for new neutron-rich isotopes. As a result, we found for the first time ^<84>Ne, ^<87>Na and ^<48>Si. In addition, we found that ^<88>Ne, ^<86>Na and ^<89>Mg are particle-unbound nuclei. The fact of the particle stability for ^<48>Si suggests a possible magicity-loss in the Z〜14 and N〜28 region. All of the findings were shown in a Journal paper as well as in a press conference.2.Development of new techniques for measuring mean-lives of excited statesTo overcome disadvantages in the RI beam fragmentation method, we developed two new methods to measure mean-lives of excited states, Doppler Shift Attenuation Method (DSAM) and the Recoil Shadow Method CRSM). These two methods were applied for two light nuclei, ^<12>Be and ^<16>C. We found that the mean-life of the first excited state of 180 is surprisingly long. This new challenging are being supported by the Grant-in-Aid for Scientific Research (A)(2) 16204017.

本研究项目所取得的研究成果概括为以下两点：1.丰中子束的发展和新丰中子同位素的发现。为了将丰中子束碎裂方法应用于较重的丰中子核(N=28)，我们用48Ca强流束流发展了适合于高效产生原子核的重离子束流。根据在RIKEN实现的一种新的加速方案，束流强度提高了大约两个数量级。为了使用强束，我们寻找了新的富含中子的同位素。因此，我们首次发现了^&lt；84&gt；Ne，^&lt；87&gt；Na和^&lt；48&gt；Si。此外，我们还发现^&lt；88&gt；Ne、^&lt；86&gt；Na和^&lt；89&gt；mg是粒子非束缚核。^&lt；48&gt；Si的粒子稳定性的事实表明，在Z~14和N~28区可能有磁性损失。2.测量激发态平均寿命的新技术的发展为了克服RI光束碎片法的缺点，我们发展了两种测量激发态平均寿命的新方法，即多普勒频移衰减法(DSAM)和反冲阴影法(CRSM)。这两种方法被应用于两个轻核，^&lt；12；Be和^&lt；16&gt；C。我们发现180的第一激发态的平均寿命令人惊讶地长。这一新的挑战得到了科学研究补助金(A)(2)16204017的支持。

项目成果

H.Sakurai: "Nuclear spectroscopy on very neutron-rich nuclei at RIKEN"Indian Journal of Physics. 76S. 61-67 (2002)

H.Sakurai：“RIKEN 的富中子核的核光谱”《印度物理学杂志》。

M.Notani et al.: "New neutron-rich isotopes,^<34>Ne,^<37>Na and ^<43>Si, produced by fragmentation of a 64A MeV ^<48>Ca beam"Physics Letters B. 542. 49-54 (2002)

M.Notani等人：“新的富中子同位素，^ 34 > Ne，^ 37 > Na和^ 43 > Si，由64A MeV ^ 48 > Ca束的碎片产生”物理快报B。

M.Notani: "New neutron-rich isotopes, ^<34>Ne, ^<37>Na and ^<43>Si, produced by fragmentation of a 64A MeV ^<48>Ca beam"Physics Letters B. 542. 49-54 (2002)

M.Notani：“新的富中子同位素，^<34>Ne、^<37>Na 和 ^<43>Si，由 64A MeV ^<48>Ca 束碎裂产生”《物理快报》B. 542. 49

N.Aoi: "Anomaly of N=8 Shell Closure in Neutron-rich Be and B Isotopes Studied via Delayed Neutron Emitting ^<14>Be beta decay"Physical Review C. 66. 014301 (2002)

N.Aoi：“通过延迟中子发射 ^<14>Be beta 衰变研究富中子 Be 和 B 同位素中 N=8 壳闭合的异常”物理评论 C. 66. 014301 (2002)

H.Iwasaki: "Large Collectivity of ^<34>Mg"Phys. Lett. B. 522. 227-232 (2001)

H.Iwasaki：“^<34>Mg 的大集体”物理学。