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Study of New-Modes of Nuclear Excitation by Means of High-Resolution (p,n) Measurement

通过高分辨率 (p,n) 测量研究核激发新模式

基本信息

批准号：
59540147
负责人：
ORIHARA Hikonojo
金额：
$ 1.73万
依托单位：
TOHOKU UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1984
资助国家：
日本
起止时间：
1984 至 1986
项目状态：
已结题

项目摘要

Charge-exchange (p,n) reactions have been proved to be an excellent tool to study new mode s of nuclear excitation , where spin-isospin excitations are observed, for example. The (p,n) reaction has been recently investigated by means of two different proton energies; i.e. (p,n) work at intermediate energy carried out at IUCF (Indiana University Cyclotron Facility), and the other works have been carried out at CYRIC (Cyclotron and Radioisotope Center, Tohoku University) with 35 MeV protons. Due to strong spin-dependent force, the intermediate (p,n) works seem to be much reliable. However, low energy (p,n) reactions may be studied with much better energy resolution. In this project, we have extensively developed the high-resolution measurement by means of the neutron time-of-flight facilities. It should be noted that to achieve a ultimated high-resolution of 100 keV v.s. 30 MeV neutrons a long flight path (44 m) is required. Thus development of the high efficient detector system was also needed.One of the current interests studied by the high-resolution (p,n) measurement is the <0^+> <-!>> <0^-> transition, which carries selectively information on one-pion exchange interaction. We have studied <DELTA> <J^pi> = <0^-> reactions on <^(13)C> , <^(14)N> and <^(15)N> . A shoulder was systematically observed around 50゜ in the angular distributions for the 1/ <2^-> <-!>> 1/ <2^+> and <1^+> <-!>> <1^-> transitions. This shoulder was interpreted as being due to the tensor interaction in the <DELTA> J( <DELTA> L, <DELTA> S) = 0 (1,1) channel. Other topics such as the <0^+> <-!>> <1^+> Gamow-Teller type transition have been extensively studied on s-d shell nuclei. One of the new modes of nuclear excitation, an example for which is <DELTA> J( <DELTA> L, <DELTA> S) = 2(1,1) or 1(1,1), were studied at <E_p> = 41 MeV for heavier nuclei.

电荷交换 (p,n) 反应已被证明是研究核激发新模式的绝佳工具，例如可以观察到自旋-同位旋激发。最近通过两种不同的质子能量研究了 (p,n) 反应；即(p,n)在IUCF（印第安纳大学回旋加速器设施）进行的中间能量工作，其他工作在CYRIC（东北大学回旋加速器和放射性同位素中心）用35 MeV质子进行。由于强大的自旋相关力，中间的 (p,n) 工作似乎非常可靠。然而，低能量 (p,n) 反应可以用更好的能量分辨率来研究。在这个项目中，我们利用中子飞行时间设施广泛开发了高分辨率测量。应该指出的是，要实现 100 keV 的最终高分辨率， 30 MeV 中子需要长飞行路径 (44 m)。因此，还需要开发高效的探测器系统。高分辨率（p，n）测量当前研究的兴趣之一是<0^+> <-！>> <0^->跃迁，它选择性地携带有关单π离子交换相互作用的信息。我们研究了 <DELTA> <J^pi> = <0^-> 关于 <^(13)C> 、 <^(14)N> 和 <^(15)N> 的反应。在 1/ <2^-> <-!>> 1/ <2^+> 和 <1^+> <-!>> <1^-> 过渡的角度分布中系统地观察到肩部在 50゜左右。该肩部被解释为由于 <DELTA> J( <DELTA> L, <DELTA> S) = 0 (1,1) 通道中的张量相互作用所致。其他主题，例如 <0^+> <-!>> <1^+> Gamow-Teller 型转变已在 s-d 壳核上进行了广泛研究。其中一种新的核激发模式，例如 <DELTA> J( <DELTA> L, <DELTA> S) = 2(1,1) 或 1(1,1)，在 <E_p> = 41 MeV 下针对较重的原子核进行了研究。