| Co-Investigator(Kenkyū-buntansha) |
KABURAGI Makoto Faculty of Cross-Cultural Studies, Kobe University Professor, 国際文化学部, 教授 (40093504)
MORII Tosiyuki Faculty of Human Development, Kobe University Professor, 発達科学部, 教授 (20031370)
HARA Tisio Faculty of Science, Kobe University Assistant Professor, 理学部, 助教授 (50156486)
KOHMOTO Tosiro Graduate School of Science and Technology, Kobe University Assistant Professor, 自然科学研究科, 助教授 (70192573)
KUNITOMO Masakazu Faculty of Science, Kobe University Professor, 理学部, 教授 (40031348)
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| Budget Amount *help |
¥1,800,000 (Direct Cost: ¥1,800,000)
Fiscal Year 1996: ¥1,800,000 (Direct Cost: ¥1,800,000)
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| Research Abstract |
The axion is a pseudoscalar Goldstone boson required by the standard model of elementary particle or QCD (the quantum chromo-dynamics) in connection with the strong CP-problem, and is also important as a leading candidate of the dark matter predicted by the current cosmology. However it has not been detected so far in spite of a lot of efforts.
We constructed an experimental apparatus to produce and detect axions, in which firstly laser photons are converted into axions in a strong magnetic field via the Primakoff effect, secondly vice versa in another magnetic field and reproduced photons are counted. We introduced a new experimental scheme which employs two optical resonators composed of high-reflectivity mirrors, one for the first and the other for the second conversion processes, to multiply the conversion efficiencies by F_1F_2 (Fi : the finesse of the i-th resonator). The signal photons expected are proportional to (gBL)^4F_1F_2 with the coupling constant g, and the magnetic field
… More
Bi(=B) and the length Li(=L).
Coherent photons from a laser enter the first optical resonator, where a strong magnetic field is applied parallel to the electric field of the photons and some of the photons are converted into axions. Because of extremely weak interaction between axions and materials, the axions go through an opaque wall freely and go into the second optical resonator, while the photons are completely blocked by the wall. The axion field is a coherent wave with substantially the same wavelength as the photon field. Some of the axions are converted into signal photons via the inverse process in the second resonator. Both of the resonators are tuned to the the same wavelength. The signal photons are detected by a single photon counter behind the second resonator.
An preliminary experiment was performed without the second resonator. Under the conditions F=3 x 10^3, L=0.97m, B=1.0 T(permanent magnets) and Pin=50 mW,an observation for 3.0 x10^3 s gave no signals. From this result, considering the quantum efficiency of 0.1, the dark count rate of 0.3 s^<-1> of the photomultiplier, and other experimental parameters, an upper limit of the coupling constant was obtained as g<1.1x10^<-5> GeV^<-1>. Less
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