PREFACEThe RIKEN Accelerator Progress Report isthe annual report of all the research activities conducted at the RIKEN Nishina Center for Accelerator-Based Science (RNC). Thisvolume, No. 54, covers the activities conducted during the Japanese ﬁscal year of 2020
(i.e., April 2020 to March 2021).
Last December, the news of the sad demise ofProf. Dr. Akito Arima, who passed away on
December 6, 2020, became widespread worldwide. As many people know, he was a distinguished physicist of the nuclear structure theory. As one of the top administrators of universities and institutes, he contributed toward thepromotion of academic activities in the ﬁeld ofscience and technology; he was also a politicianof the House of Councilors and ministers of the government. He was the President of RIKEN from 1993 to 1998;
during this period, he launched three major research activities at the current RNC: realizing the RI Beam Factory(RIBF) project, and establishing the RAL branch oﬃce for muon sciences and the RIKEN BNL Research Center(RBRC) for high-energy nuclear physics. Following the commencement of its operation in 2007, the RIBF has
become one of the best facilities worldwide for low-energy nuclear physics. I was incredibly happy to present him
with the achievements of the RIBF at the conference in Shanghai in 2018, as a celebration of his 88th birthday.
Furthermore, he also encouraged international relationships with Asian countries, especially China and Vietnam,
and signiﬁcantly improved research collaboration. At the RNC Monthly Meeting held on December 9, 2020, all
the RNC members oﬀered a silent prayer in view of his considerable achievements and contributions. As a person,
he was known for his ﬁrm philosophy and humanity; he loved nature, physics, and the youth. At this occasion,
I would like to oﬀer my deepest condolences and also express my sincere respect for his guidance across a wide
range of ﬁelds.
In 2020, the world was aﬀected by the COVID-19 pandemic. Consequently, given that the coronavirus is carried and spread by people, people’s activities have been severely restricted. Nevertheless, personal relationships
remained intact owing to advances in the Internet. As a result, many discoveries pertaining to human communication through various online/virtual activities have been reported. For instance, all the PAC meetings inFY2020 were organized remotely. Furthermore, certain symposia and workshops were conducted in a hybrid stylecombining in-person and online communications.
Onsite activities, where people and things/facilities interact, form the essence of technological development andexperimental research. It is, therefore, considerably important to implement measures for preventing the spreadof the coronavirus. At the RIBF, we were able to avoid a divide between people and things/facilities, while
sustaining the research activities. Local and domestic staﬀ members realized achievements in terms of developing
facilities and conducting experiments. One such achievement is the upgrade of the RILAC (SRILAC) and thecomplete installation of GARIS-III; this represents the completion of the preparation for moving forward withnovel research. Furthermore, we succeeded in increasing the 70 Zn and 238 U beam intensities at the SRC, thus
realizing a high-intensity beam for the HiCARI campaign using “tracking” germanium detectors and the massmeasurement of many unknown nuclei during the MR-TOF experiment performed in parallel.
However, onsite research activities were still stagnant, given the restrictions on people traveling across borders
and overseas. This resulted in a divide between people and things/facilities at the overseas research facilities of
the RHIC and RAL and the joint international research at the RIBF.
Seventeen press releases were issued in FY2020, and selected achievements of 2020 are compiled in the “Highlightsof the Year” section of this volume. These indicate the growing multi-disciplinary activities at the RNC forscience, technology, and innovation. It should be noted that these achievements were made not only by in-house researchers and engineers at the RNC but also by collaborating users at the RIBF, RBRC, and RAL. Thepaper titled “Surface localization of the dineutron in 11 Li,” which was published in Physical Review Letters, is a
result of the first spectroscopy with fully completed kinematics measurements conducted at SAMURAI in orderto demonstrate the dineutron component in 11 Li. With regard to heavy-ion beam breading, the paper titled“Improvement of rotifer as the new food item in larviculture” had a significant impact on the society, and theresults were featured as “Godzilla the rotifer” in the Economist magazine issued January 23, 2021.
Awards were also presented to the colleagues of the RNC. Takahiro Nishi was presented with the 17th Annual
Meeting Award of the Particle Accelerator Society of Japan, and Takashi Ichihara was presented with the 2020
JPCERT/CC Certificate of Gratitude, JPCERT Coordination Center. Furthermore, the Nishina Memorial Prize
was awarded to Kazuma Nakazawa, a visiting scientist at the Strangeness Nuclear Physics Laboratory.
With regard to the organization of the RNC, Hiroyuki Ichida and Masanori Kidera were appointed as the Team
Leaders of the Plant Genome Evolution Research Team and the Infrastructure Management Team, respectively,
as of October 2020.
The coronavirus crisis is expected to continue even after 2021. Nevertheless, we are extremely grateful to be
blessed with an environment that allows us to continue with our research. Hence, it is vital that we acknowledge
the mission of RIKEN and aggressively accept new challenges in research and development activities.

Hiroyoshi Sakurai
Director
RIKEN Nishina Center for Accelerator-Based Science