EAPSI: Variable Energy Positron Beam for Positronium Diffraction

该奖项支持一名美国研究生参与使用东京科学大学(TUS)教授长岛康之(Yasuyuki Nagashima)开发的新型正电子束进行的尖端实验。长岛光束由正电子粒子组成，这些粒子将从固体表面衍射。在实验中，正电子粒子将从固体表面衍射，提供了一种独特的中性粒子光谱方法，与传统的中性粒子光谱方法相比，具有几个优点，包括粒子尺寸和减少样品表面的损伤。这项实验还将首次观测到正电子从固体表面的衍射，为理论量子力学提供有价值的实验证据，并为其他光谱方法的发展提供实验结果。未来的实验可能包括研究开发燃料电池的多孔和催化材料，以及利用太阳能从水中生产氢气。这项工作也将有助于TUS长岛实验室和德克萨斯大学阿灵顿分校(UTA)正电子表面实验室小组的合作。长岛康之教授和他的研究小组与高能加速器研究组织(KEK)合作，成功地利用电子从负正电子离子中光分离的方式构建了早期的正电子束，目前正在建造一种新的正电子束。利用这种独特的方法，这种能量可调的束流超过了以前400 eV的束流能量极限，测得的最小和最大能量分别为300 eV和1.9keV，并有可能获得更高的能量。新的光束S具有高通量、更好的准直性和更低的能量分散的特性，将使观察多个衍射光束和测量衍射的能量依赖关系成为可能。利用这一预计于2015年春季完成的新正电子束，将进行包括观察来自固体表面(即Si和LiF)的高能正电子衍射的实验。该NSF EAPSI奖是与日本科学促进会合作资助的。

This award supports participation of a U.S. graduate student in a cutting edge experiment using the new positronium beam developed by Professor Yasuyuki Nagashima of Tokyo University of Science (TUS). The Nagashima beam consists of positronium particles, which will be diffracted from solid surfaces. In the experiment, positronium particles will be diffracted from solid surfaces, providing a unique neutral-particle spectroscopic method with several advantages over conventional neutral-particle spectroscopy, including particle size and the reduction in damage of the surface of the sample. This experiment will also provide the first observation of the diffraction of positronium from solid surfaces, providing valuable experimental evidence for theoretical quantum mechanics, as well as experimental results that will aid in the development of other spectroscopic methods. Future experiments may include the study of porous and catalytic materials for the development of fuel cells and the production of hydrogen from water using solar energy. This work will also contribute to the collaboration between the Nagashima laboratory at TUS and the Positron Surface Laboratory group at the University of Texas at Arlington (UTA).Professor Yasuyuki Nagashima and his research group, in collaboration with the High Energy Accelerator Research Organization (KEK), successfully constructed an earlier positronium beam using the photo-detachment of electrons from negative positronium ions, with a new positronium beam currently under construction. Using this unique method, this energy-tunable beam surpassed the previous beam energy limit of 400 eV, with measured minimum and maximum energies of 300 eV and 1.9 keV, respectively, and higher energies possible. The new beam?s properties of high flux, better collimation, and lower energy spread will enable the observation of multiple diffraction beams and the measurement of the energy dependence of the diffraction. Using this new positronium beam, which is expected to be completed by spring 2015, experiments consisting of the observation of high-energy positronium diffraction from solid surfaces, namely Si and LiF, will be performed. This NSF EAPSI award is funded in collaboration with the Japan Society for the Promotion of Science.