2022 Fiscal Year Annual Research Report
Electron electric dipole moment search by using polarized ultracold molecule s
| Project/Area Number |
21H01113
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| Allocation Type | Single-year Grants |
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| Research Institution | Okayama University |
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Principal Investigator |
DOYLE JOHN 岡山大学, 異分野基礎科学研究所, 客員教授 (50870432)
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| Co-Investigator(Kenkyū-buntansha) |
吉村 浩司 岡山大学, 異分野基礎科学研究所, 教授 (50272464)
増田 孝彦 岡山大学, 異分野基礎科学研究所, 特任准教授 (90733543)
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| Project Period (FY) |
2021-04-01 – 2025-03-31
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| Keywords | electric dipole moment / buffer gas cooling / thorium oxide |
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| Outline of Annual Research Achievements |
In FY2022, the big laser port window whose diameter is 160 mm was developed. The window was required to have small enough stress-induced birefringence to maintain the laser polarization. We adopted SF57HTultra as a window material and confirmed that it satisfies the requirement. For the confirmation, the Co-I and his graduate student built a laser polarization measurement setup at Okayama university. It consists of ECDL (External cavity diode laser) and a vacuum chamber. The SF57HTultra was set as the vacuum window to measure the stress-induced birefringence due to the atmospheric pressure.
A vacuum leak problem in the photodetector that was identified at the end of FY2022. In FY2023 first, the leak was addressed. The vacuum window was found to be the leak point. Since there was no problem during prototyping and immediately after mass production, the leak was thought to be caused by aging deterioration. The original design used a square vacuum window sealed with adhesive, but this was changed to a circular window sealed with an O-ring. We have confirmed that the modified photodetectors do not have vacuum leak and the reliability has been improved. The modified 10 detectors are already installed in FY2023.
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| Current Status of Research Progress |
Current Status of Research Progress
2: Research has progressed on the whole more than it was originally planned.
Reason
We have confirmed that SF57HTultra is a good material for the big laser port which is required to be low stress-induced birefringence. The windows will be installed.
Even though the photodetectors produced in the first cycle were found to have vacuum imperfections, we have addressed that problem in FY2023. It did not delay the entire project; therefore, we think this project is progressing rather smoothly.
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| Strategy for Future Research Activity |
The experimental apparatus construction that was started in the middle of 2022 has been almost settled down in 2023. Some of the apparatus, such as magnetic shields and coils which are prepared by the collaborators are still under investigation, but many parts are ready for the pilot run which aims to check possible systematic uncertainty sources before the physics run.
The PI is responsible for the thorium-monoxide buffer gas beam source as well as managing the entire project. The main issue would be the stability of the beam. The Co-Is are mainly responsible for the detector operation and data acquisition system. The Co-I will visit the experimental site in the US several times to manage the detectors and the data acquisition system. Also, he will prepare a remote control and monitoring system to operate the systems from Japan to experiment smoothly.
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