Projectile Fragmentation Mechanism and Production of Aligned Spin-stretched Isomers

弹丸碎裂机制和对齐旋转拉伸异构体的生产

• 批准号: 04640287
• 负责人: ASAHI Koichiro
• 金额: $ 1.41万
• 依托单位: Tokyo Institute of Technology
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for General Scientific Research (C)
• 财政年份: 1992
• 资助国家: 日本
• 起止时间: 1992 至 1993
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-04640287/
• 关键词: projectile fragmentation; spin alignment; isomeric ratio; participant-spectator model; spin-aligned radioactive beams; neutron-rich nuclei; nuclear magnetic moment; quadrupole moment; スピン偏極

The spin orientation and the isomer production ratio for ejectiles from high-energy projectile fragmentation reactions have been studied in order to clarify the reaction mechanism and to develop a method to produce spin-oriented radioactive nuclear beams, The experiments were performed (1) in the 500 MeV/u and (2) in the 100 MeV/u regions.(1) in the 500 MeV/u regin, fragments ^<43>Sc were produced through removing three nucleons from projectiles ^<46>Ti by the collision with a Be target. For the 19/2^- isomer of the ^<43>Sc, which is known to represent a spin-stretched state of a (f_<7/2>)^3 configuration, the mesurements were made of i)the isomer production ratio and ii)the spin orientation of rank 2 (i, e. the alignment). (2)In the 100 MeV/u region, projectiles of ^<15>N, ^<18>O, and ^<22>Ne were used and the rank-1 orientation (polarization) was measured for fragments produced in the fragmentation process. Also, this scheme of polarization was applied to measurents of the fragmentat … More ion process. Also, this scheme of polarization was applied to measurents of the magnetic moments and electric quadrupole moments.From the measurements described above. following results were obtained. (1)The observed isomer production ratio shows a clear momentum dependence characteristic of a behavior predicted from a participant-spectator model for the fragmentation process. (2)The spin alignment of the isomer changes from positive values at the center momentum of the Goldhaber distribution to negative values with magnitudes as large as 20% at the wing momenta, agein showing a good agreement with the participant-spectator model. (3)The polarization studied in the 100 MeV/u region showed a sytematic variation over different enegries and targets and, together with the results (1) and (2), proved general validity of the above simple model for the spin orientation observable in the 100-500 MeV/u fragmentation reactions, Utilizing the thus confirmed phenomenon of the fragment spin orientation, the magnetic moments for neutron-rich nuclei ^<14>B, ^<15>B, ^<17>N, and ^<21>F and the quadrupole moments for ^<14>B and ^<15>B were newly determined. Less

为了阐明反应机理并开发产生自旋定向放射性核束的方法，对高能射弹碎裂反应中弹射物的自旋取向和异构体产生率进行了研究。实验分别在（1）500 MeV/u 和（2）100 MeV/u 区域进行。（1）在 500 MeV/u 区域，碎片^<43>Sc 为 通过与Be靶碰撞从射弹^<46>Ti去除三个核子而产生。对于 ^<43>Sc 的 19/2^- 异构体，已知其代表 (f_<7/2>)^3 构型的自旋拉伸状态，测量由 i) 异构体生产比率和 ii) 2 级自旋取向（即排列）组成。 (2)在100MeV/u区域，使用^ 15 N、^ 18 O、^ 22 Ne射弹，测定破碎过程中产生的碎片的1级取向(偏振)。此外，这种极化方案还应用于碎片离子过程的测量。此外，这种极化方案还应用于磁矩和电四极矩的测量。根据上述测量。得到以下结果。 (1)观察到的异构体生产比率显示出根据碎片过程的参与者-观众模型预测的行为的明显动量依赖性特征。 (2)异构体的自旋排列从Goldhaber分布中心动量处的正值变化到翼动量处幅度高达20%的负值，agein与参与者-观众模型表现出良好的一致性。 (3)在100 MeV/u区域研究的极化表现出不同能量和目标的系统变化，并与结果(1)和(2)一起证明了上述简单模型对于100-500 MeV/u碎片反应中可观察到的自旋方向的普遍有效性，利用由此证实的碎片自旋方向现象，富中子核的磁矩 新测定了^ 14 B、^ 15 B、^ 17 N、^ 21 F以及^ 14 B、^ 15 B的四极矩。较少的

项目成果

K.Asahi and M.Ishihara: "Spin-polarized Radioactive Beams and Their Applications" RIKEN Reviews. 4. 9-10 (1994)

K.Asahi 和 M.Ishihara：“自旋极化放射性束及其应用”RIKEN 评论。

H.Ueno,et al.: "Spin-polarized Radioactive Beams and β-NMR Experiments" Proc.Int.Symp.on Unstable Nuclei and Particles as Probes in Physics and Chemistry,Wako,Japan,1992.(1993)

H. Ueno 等人：“自旋极化放射性束和 β-NMR 实验”Proc.Int.Symp.on Unstable Nuclei and Particles as Probes in Physical and Chemistry，Wako，日本，1992 年。(1993)

K.Asahi et al.: "Spin Polarization by Abrasion Process in Intermediate-energy Heavy-ion Collision and Its Application" Proceedings of Japan-China Joint Nuclear Physics Symposium,Tokyo,Japan,November 1992.(1993)

K.Asahi等：“中能重离子碰撞中磨损过程的自旋极化及其应用”日中联合核物理研讨会论文集，日本东京，1992年11月。（1993年）

H.Okuno, K.Asahi, et al.: "Systematic Behavior of Ejectile Spin Polarization in the Projectile Fragmentation Recation" Phys.Lett.B.(to be published).

H.Okuno、K.Asahi 等人：“弹丸碎片修复中弹射自旋极化的系统行为”Phys.Lett.B.（待出版）。

K.Asahi: "Fragment Spin Polarization and Its Application" Proceedings of 6th International Conference on Nuclei Far From Stability,Bernkastel-Kues,Germany,1992.(1993)

K.Asahi：“碎片自旋极化及其应用”第六届远离稳定核国际会议论文集，Bernkastel-Kues，德国，1992年。（1993）