암흑물질 후보 액시온 탐색으로 우주 생성 원리 규명
대전시 유성구 문지로 193, KAIST 문지캠퍼스 창조관 C301호
IBS 액시온 및 극한상호작용 연구단
연구단장 야니스 세메르치디스
카이스트 물리학과 교수이자 액시온 및 극한상호작용 연구단의 단장이다.
미국 브룩헤이븐국립연구소에서 액시온관련 실험들을 수행하여 1989년 뉴욕의 로체스터 대학교에서 PhD 학위를 수여받았다.
이후에 BNL물리학부서에 합류하게 되었고 뮤온물리학 뿐만 아니라 강성자의 전기 쌍극자모멘트(hadronic EDM)를 측정하는 신기술을 창안하였다. 이러한 업적으로 미국물리학회 회원 및 BNL의 영년직 선임과학자의 직위에 올랐고 수차례 공로상을 받기도 했다.
액시온장은 우주전체에 퍼져있으며 암흑물질의 비밀을 지니고 있다
The IBS Center for Axion and Precision Physics Research (CAPP) is located in Daejeon City at the Korea Advanced Institute of Science and Technology (KAIST). Our center has launched several state of the art axion dark matter experiments with the best sensitivity in the world for our frequency of interest. CAPP also plays a leading role in the proton electric dipole moment experimental international effort and participates in the muon g-2 experiments at Fermilab in the USA and at J-PARC in Japan.
The latest measurements indicate that dark matter constitutes about 25% of the energy in the universe. Among the leading dark matter candidates are particles such as axions, and weakly interacting massive particles (WIMPs), e.g., the lightest supersymmetric particle. (WIMP searches are the subject of several groups around the world including the IBS Center for Underground Physics in Korea.) Axions were postulated to solve a large problem in strong interactions: even though the theory of strong interactions predicts a large violation of certain symmetries, those of P-parity and T-time reversal, the limit on the electric dipole moment (EDM) of the neutron is already too small, some ten orders of magnitude smaller than expected.
A massive axion is excluded by several experiments and astrophysical limits. A prominent Korean theorist prof. Jihn E. Kim suggested that a light-mass axion would also work as well. The light axions have the advantage that they could constitute the dark matter of our universe. It is currently believed that axion masses roughly between 0.001 meV and 1meV could be ideal dark matter candidates. Depending on their mass, there could be about 1014axions/cm3, to fill the dark matter density quota of about 0.5GeV/cm3.
We are currently using a method suggested by Prof. P. Sikivie, to convert the axions into microwave photons inside a large volume, high magnetic field, and a high-quality microwave cavity. We are also exploring different geometries that can prove to be even more advantageous. The expected conversion rate is very small, of order 10-23W, making it the faintest signal possible in a realistic experiment.
Once the axions are discovered, a new physics field, axion astrophysics, may be launched, opening new horizons in our knowledge of the universe and the dynamics of our galaxy.
In addition, the center is playing a leading role in the storage ring proton EDM experiment to improve the sensitivity by several orders of magnitude down to 10-29ecm, making it the best hadronic EDM experiment in the world. A successful proton EDM experiment could help explain the matter-antimatter asymmetry mystery of our universe. In the muon g-2 experiment, testing the standard model to high accuracy, we are developing the RF-system used for the elimination of the coherent betatron oscillations and muon losses, both leading systematic error sources in the experiment.