Development of a neutron-polarizing device based on a quadrupole magnet and its application to a focusing SANS instrument

Oku Takayuki

doi:10.5611/hamon.19.3_140

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Other Title

四極磁石に基づく中性子高偏極デバイスの開発と集光型中性子小角散乱法への応用
受賞記事四極磁石に基づく中性子高偏極デバイスの開発と集光型中性子小角散乱法への応用
ジュショウキジ 4キョクジシャクニモトズクチュウセイシコウヘンキョクデバイスノカイハツトシュウコウガタチュウセイシショウカクサンランホウエノオウヨウ

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<p>We have investigated suitable magnetic field distribution to polarize neutrons based only on the electromagnetic interaction between a neutron magnetic moment and magnetic field, and found out a quadrupole field was the most suitable among simple multipole fields. Then we constructed a quadrupole magnet with a Halbach magnetic circuit as the neutron polarizing device. A cold neutron polarizing experiment of the quadrupole magnet was performed at the beamline C3-1-2-1 (NOP) of JRR-3 at JAEA. By passing through the aperture of the quadrupole magnet, positive and negative polarity neutrons are accelerated in opposite directions and spatially separated. Therefore, we extracted the one-spin component and analyzed its polarization degree. As a result very high neutron polarization degree P=0.9993±0.0025 was obtained. Then the quadrupole magnet was installed into the polarized neutron focusing geometry SANS instrument SANS-J-II of JRR-3. The instrument performance was enhanced by about 10 times compared with the case with the magnetic supermirror as the neutron polarizing device. The details are shown and discussed.</p>

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hamon

hamon 19 (3), 140-145, 2009

The Japanese Society for Neutron Science

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