EAPSI: Variable Energy Positron Beam for Positronium Diffraction

该奖项支持一名美国研究生参与东京科学大学（TUS）教授Yasuyuki Nagashima开发的新型正电子电子束的尖端实验。Nagashima光束由正电子粒子组成，它将从固体表面衍射。在实验中，正电子粒子将从固体表面衍射，提供一种独特的中性粒子光谱方法，与传统的中性粒子光谱相比，它具有几个优点，包括颗粒大小和减少样品表面的损伤。该实验还将提供固体表面正电子衍射的第一次观测，为理论量子力学提供有价值的实验证据，以及有助于其他光谱方法发展的实验结果。未来的实验可能包括多孔材料和催化材料的研究，用于发展燃料电池和利用太阳能从水中生产氢。这项工作也将有助于美国德克萨斯大学长岛实验室和德克萨斯大学阿灵顿分校正电子表面实验室小组之间的合作。Yasuyuki Nagashima教授和他的研究小组与高能加速器研究组织（KEK）合作，利用电子与负正电子离子的光分离，成功地构建了一个早期的正电子束，目前一个新的正电子束正在建设中。利用这种独特的方法，这种能量可调光束超越了之前400 eV的束流能量极限，测量到的最小和最大能量分别为300 eV和1.9 keV，并且可能更高的能量。新横梁？高通量、较好的准直性和较低的能量扩散等特性，将使多重衍射光束的观测和衍射能量依赖性的测量成为可能。利用这束预计将于2015年春季完成的新正电子光束，将进行从固体表面（即Si和LiF）观察高能正电子衍射的实验。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.