K. Harada

An accelerator experiment for junior and senior high school students to improve students' involvement in fundamental physics

K. S. Tanaka, K. Harada [1], T. Hayamizu [1], R. Kita [1], R. Kono [1], K. Maruta [1], H. Nagahama [1], N. Ozawa [1], Y. Sakemi [1], R. Sugimori [1]

Abstract

In Japan, research activities by junior and senior high school students show an upward trend. However, there are limited examples of research activities in the field of elementary particles and atoms. This is due to the difficulty associated with procuring research tools such as accelerators or particle detectors. Therefore, we hosted the "Accel Kitchen" in 2018 and 2019 at Cyclotron and Radioisotope Center (CYRIC) in Tohoku University where junior and senior high school students could participate in ongoing research of particle and atomic physics. At each workshop, 12 junior and senior high school students participated in the beam experiment, including the production of francium atoms (Fr) by the fusion reaction of oxygen and gold, optimizing the transport of the ion beam and identifying the alpha decay nuclei, and laser trapping of Fr for two days. Each group that was involved in the experiment was supported by researchers and university students who acted as mentors. This was the first opportunity for junior and senior high school students to know about the particle beam experiment in Japan.

Thermal surface neutralization of Fr ions with metal foils for magneto-optical trapping of radioisotopes

H. Kawamura [1,2], T. Aoki [2], K. Harada [2], T. Inoue [1,2], S. Ito [2], K. Kato [2,3], L. Koehler, K. Sakamoto [2], A. Uchiyama [2], Y. Sakemi [4]

Abstract

We investigate neutralization processes (especially thermal surface neutralization), which are required for the magneto-optical trapping of radioactive atoms. A variety of neutralization methods are first summarized: neutral beam injection for fusion reactors, neutral atom implantation in semiconductor processing, and the production of radioactive neutral atoms in accelerators. We focus on thermal surface neutralization, which produces neutral atoms in the thermal energy range for laser cooling. The experiments were carried out with yttrium, gadolinium, and zirconium foils to neutralize francium and rubidium ions for magneto-optical trapping. The results reconfirm that yttrium foil is a good neutralizer (i.e., it has a neutral release efficiency $>65\%$). In addition, the release fraction when using yttrium foil exceeds 75\% at 1350 K, which is greater than the release fraction for the other foils. This reconfirmation is important because few previous studies have focused on thermal surface neutralization. Moreover, the results show that the neutralization efficiency is strongly influenced by the experimental process itself.