2004 Fiscal Year Final Research Report Summary
Proposal and theoretical investigation with optimization for nuclear spin-polarization using intense laser pulses
| Project/Area Number |
14540262
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
素粒子・核・宇宙線
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| Research Institution | Kyoto University |
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Principal Investigator |
NAKAJIMA Takashi Kyoto University, Institute of Advanced Energy, Associate Professor, エネルギー理工学研究所, 助教授 (50281639)
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| Project Period (FY) |
2002 – 2004
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| Keywords | Spin-polarization / Autoionization resonance / ultrafast laser pulse / polarized source |
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| Research Abstract |
(1)We came to the idea that there may be a possibility to polarize electron-spin of residual ions if one can polarize spin of photoelectrons. Based on this assumption, we have pursued the possibility of the simultaneous production of spin-polarized electrons/ions upon photoionization. Alkaline-earth atoms are ideal for such investigation, and we have chosen Sr for a target atom. Two schemes are considered : The first one is one-photon resonant two-photon ionization, and the second one is one-photon resonant one-photon ionization. After the theoretical study, we have found that 66% spin-polarization is possible for the latter, while >90% spin polarization is possible for the former at the expense of more than few orders of magnitude smaller yield.
(2)Based on the theoretical result in (1), we have performed experimental study, and obtained 64% spin-polarization as we expected. This experimental result is an important cornerstone toward the construction of a spin-polarized source.
(3)In order to achieve a better performance as a spin-polarized source, it is essential to improve the degree of spin-polarization and yield. For that purpose, the use of autoionizing resonance seems to be a promising scheme. We have replaced a wavelength-fixed ionization laser (excimer laser) by a tunable dye-laser, and carried out experiments to find that the significant improvement of spin-polarization (64% to 78%) and two-orders of magnitude improvement in terms of yield. Furthermore, we have theoretically investigate a new scheme to polarize spin using short laser pulses.
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