18-22 October 2021
Matsue, Shimane Prefecture, Japan
Asia/Tokyo timezone

Development of Iron Thin Films for Polarization Analysis of Ultracold Neutrons

19 Oct 2021, 19:30
Room 403 (Kunibiki Messe)

Room 403

Kunibiki Messe

Parallel Session Presentation Future facilities and experiments Joint BSM - Accelerator - Future Session EU timezone


Hiroaki Akatsuka (Nagoya University)


The TRIUMF Ultra-Cold Advanced Neutron (TUCAN) collaboration aims to measure the neutron electric dipole moment (EDM) with a sensitivity of $10^{-27} e·\rm cm$ with a high-intensity ultracold neutron (UCN) source. Our target accuracy is an order-of-magnitude improvement over the current best experimental limit of the neutron EDM [1]. In the neutron EDM measurement, the Larmor precession frequency of UCNs stored in a cell under a magnetic and an electric fields is measured by Ramsey’s technique of separately oscillating fields [2]. One of the essential steps of this measurement is polarization analysis of the UCNs, which is done by a polarization analyzer consisting of an iron thin film surrounded by a permanent magnet, and a UCN detector.

We are developing iron thin films for the polarization analyzer. They are required to have high saturation magnetizations and low coercivities. We produce ones with lower coercivities than those used in previous studies [3]. The advantages of them are that the leakage magnetic field can be reduced, and that the detector can be easily enlarged. We have characterized thin iron films produced by the ion beam sputtering facility [4] at the Institute of Combined Nuclear Science, Kyoto University, by neutron reflectivity measurements at J-PARC BL05 and vibrating sample magnetometry. In this talk, the results of these characterization measurements will be presented.

[1] C. Abel et al., Phys. Rev. Lett. 124, 081803 (2020).
[2] N. F. Ramsey, Phys. Rev. 78, 695 (1950).
[3] S. Afach et al., Eur Phys J. A 51, 143 (2015).
[4] M. Hino et al., Nucl. Inst. Meth. A 797, 265 (2015).

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