AAPPS-APCTP CN Yang Award 2021

FU-JEN KAO (The Chair of the CN Yang Award Committee)

We are very pleased to announce the three outstanding and prospective young scholars who are receiving the 2021 AAPPS-APCTP CN Yang Award (CN Yang Award). Over the years, the number of candidates has been increasing and the selection process of the CN Yang Award has become more structured, reflecting the increasing capabilities of the Association of Asian Pacific Physical Societies (AAPPS) and the academic vibrancy in the Asia-Pacific region. With the revised nominating rules (http://www.aapps.org/myboard/list_blog.php?Board=chen_ning_yang), there are 27 nominations from AAPPS societies and divisions and four nominations from individual scholars of APPC this year (Table 1). All the candidates certainly merit an honorable mention, due to their excellent qualifications.

Table 1 The nationalities and the sessions of the 2021 CN Yang Award nominees

The CN Yang Award was established to honor and encourage young researchers with prominent research achievements and to promote the next generation's leading scholars in physics in the Asia Pacific region. This award had been presented during the Asia Pacific Physics Conference, which has been held approximately every three years. Notably, starting in 2019, the Association of Asia Pacific Physical Societies (AAPPS) and the Asia Pacific Center for Theoretical Physics (APCTP) jointly established the AAPPS-APCTP Chen-Ning Yang Award (CN Yang Award) to make it an annual event. The CN Yang Award Committee has been formed to choose the most promising candidates and consists of members from the AAPPS Council, AAPPS Divisions, and renowned scholars recommended by APCTP.

The selection process is highly challenging, considering the excellent qualifications of the nominees and the diversity of their fields. Naturally, the originality of the candidates' works, their established impact, and their likely prospects are very important areas of consideration.

Through the process, it has been a pleasure to learn about the candidates' works and achievements. The citations and the briefings for the awardees are listed below.

Chen Fang (), Institute of Physics, Chinese Academy of Sciences

"For his founding contribution in coining higher-order topological insulators and in completing a fast-diagnosis scheme for topological materials"

Dr. Chen Fang received his PhD from Purdue University in Dec. 2011. He then was a postdoctoral research associate from 2012 to 2015 at Princeton University, the University of Illinois, and Massachusetts Institute of Technology. He subsequently joined the faculty at the Institute of Physics, Chinese Academy of Sciences. Since then, he has focused on topological states of condensed materials, which are known to exhibit exotic phenomena, such as the negative linear magnetoresistance in the bulk of topological semimetals and the robust and gapless modes on the surface of topological insulators.

Dr. Fang has played a key role in solving two important problems in this field, known as "diagnosis" and "classification", with the key concept of the "topological invariant", a global quantum number that is used to distinguish topological materials from non-topological ones and to classify various types of topological materials. Note that the types and forms of all topological invariants depend only on two factors: symmetry and dimensionality. Identifying all invariants for a given dimension and symmetry group of interest is, therefore, an important classification problem for theorists. Dr. Fang's recent works in Phys. Rev. Lett. 119, 246402 (2017) and Nature Communications 9, 3530 (2018), for the first time, identify four new Z2 topological invariants in 3D for the following spatial symmetries: rotation, screw rotation, roto-reflection, and inversion. He then used a theoretical tool, "layer construction", to solve the classification problem.

While classification is a purely theoretical topic, the "diagnosis" is more related to realistic materials. By addressing the actual values of the invariants of a given material based on first-principle calculations, Dr. Fang and his group have developed a new method and applied it to ~ 40,000 materials in a database. They have successfully predicted ~ 8,000 materials to be topological semimetals and insulators, exceeding by an order of magnitude the total number of such materials theoretically discovered in the past ten years.

Masashi Otani (大谷 将士), The High Energy Accelerator Research Organization (KEK)

"For his development of the muon linac in realizing muon acceleration for the first time in the world"

Dr. Otani has succeeded in high-frequency acceleration of muons for the first time in the world. He devised the unique combination of muon cooling by generating negative muonium ions (the bound state of a positive muon and two electrons), decelerating muons down to less than 1 KeV (by simply injecting muons into a thin metal film), and then accelerating and bunching muons with a radio-frequency quadrupole linear accelerator (RFQ). This unique method has solved a decades-old problem in a limited experimental environment and will be the basis for a variety of future projects in high energy physics, including the precise measurement of muons and the creation of a neutrino factory and a muon collider.

Dr. Otani has been leading the muon acceleration program for the muon g-2/EDM experiment at J-PARC since 2013, after receiving his PhD in physics for the measurement of neutrino oscillation in the T2K long baseline experiment.

Yangping Shen (谌阳), Department of Nuclear Physics, China Institute of Atomic Energy

"For his contribution in shedding new light on the critical reaction, ¹²C(α, γ)¹⁶O, in nuclear astrophysics"

¹²C(α, γ)¹⁶O is regarded as the "Holy Grail" reaction in the nuclear astrophysical research, which affects the synthesis of the elements up to iron and governs stellar evolution, including the formation of black holes or neutron stars as massive stars exhaust their energy.

Dr. Shen's works mainly focus on the direct and indirect measurement of this "Holy Grail" reaction. He has developed an indirect technique based on the independent (¹¹B, ⁷Li) transfer reaction with less breakup effect and has experimentally determined the external-capture contribution in ¹²C(α, γ)¹⁶O for the first time. This work results in a significant increase of the total S factor, which is now in good agreement with the value obtained by reproducing supernova nucleosynthesis calculations with solar-system abundances.

Furthermore, Dr. Shen is the key contributor of the "Jinping Underground Nuclear Astrophysics" project and leads the underground experiment to directly approach the Gamow window of ¹²C(α, γ)¹⁶O for the first time in the world. His experiment has already achieved a sensitivity more than one order of magnitude higher than the previous best record.