Proton Polarization at Room Temperature wih Laser and it's application

激光质子室温偏振及其应用

基本信息

批准号：
07554006
负责人：
MASAIKE Akira
金额：
$ 12.1万
依托单位：
KYOTO UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (A)
财政年份：
1995
资助国家：
日本
起止时间：
1995 至 1997
项目状态：
已结题

项目摘要

We have polarized protons in molecular crystals of naphthalene doped with pentacene using a dye laser in 3 KGauss at the temperature higher than 77 Kelvin. In this new method electrons are excited to high singlet states with the laser beam, where the spin-orbit interaction causes the transition from singlet states to intermediate triplet states. The populations of the Zeeman sublevels of the lowest triplet states with Z-components of the total electron spin+1,0, -1 are 12,76 and 12% respectively. During the lifetime of the triplet state (some 20 microsec) microwave irradiation occurs and the external field is swept simultaneously to transfer the population difference of electrons between two Zeeman sublevels to the proton polarization by means of the integrated solid effect. Electrons on the triplet states decay to the ground state, where the proton spin remains polarized for a long time.We have tried to polarize protons in naphthalene doped with pentacene (0.01 mol%) with a high-power pulsed dye-laser (lambda=590-605nm) and got about 34% polarization at liquid nitrogen temperature. The enhancement factor corresponding to this value is 8*10^4. The relaxation times of protons are about 1,000 and 160 minutes in hte field of 3KG and 7G respectively. The method is applicable to the wide fields of spin physics. Since the target has no heating problem and no serious problem of radiation damage, it can be used for high-intensity beams of hadrons and electrons. Secondly, the target is useful for experiments with very low-momentum charged particles, since the necessary magnetci field to keep the polatization is extremely low.

我们使用 3 KGauss 的染料激光在高于 77 开尔文的温度下对掺杂并五苯的萘分子晶体中的质子进行了偏振。在这种新方法中，电子被激光束激发到高单线态，其中自旋轨道相互作用导致从单线态到中间三线态的转变。总电子自旋+1,0,-1 的 Z 分量的最低三重态的塞曼子能级的布居分别为 12,76 和 12%。在三重态寿命（约20微秒）期间，发生微波照射并同时扫描外场，通过积分固体效应将两个塞曼亚能级之间的电子布居差转移到质子极化。三重态上的电子衰变到基态，质子自旋在很长一段时间内保持极化。我们尝试用高功率脉冲染料激光（lambda= 590-605nm)，在液氮温度下获得约34%的偏振。该值对应的增强因子为8*10^4。质子的弛豫时间在3KG和7G的场中分别约为1000和160分钟。该方法适用于自旋物理的广泛领域。由于该靶材不存在发热问题，也没有严重的辐射损伤问题，因此可用于强子和电子的高强度束流。其次，该靶对于动量极低的带电粒子实验非常有用，因为保持极化所需的磁场极低。