Ultracold neutron energy spectrum and storage properties from magnetically induced spin depolarization

N. J. Ayres; G. Ban; G. Bison; K. Bodek; V. Bondar; T. Bouillaud; D. Bowles; G. L. Caratsch; E. Chanel; W. Chen; P. -J. Chiu; C. B. Crawford; V. Czamler; M. Daum; C. B. Doorenbos; M. Ferry; M. Fertl; A. Fratangelo; D. Galbinski; W. C. Griffith; Z. D. Grujic; K. Kirch; V. Kletzl; B. Lauss; T. Lefort; A. Lejuez; R. Li; K. Michielsen; J. Micko; P. Mullan; A. Mullins; O. Naviliat-Cuncic; D. Pais; F. M. Piegsa; G. Pignol; C. Pistillo; D. Rebreyend; I. Rienäcker; D. Ries; S. Roccia; D. Rozpedzik; W. Saenz-Arevalo; L. Sanchez-Real Zielniewicz; P. Schmidt-Wellenburg; E. P. Segarra; L. Segner; N. Severijns; K. Svirina; K. S. Tanaka; J. Thorne; J. Vankeirsbilck; N. von Schickh; N. Yazdandoost; J. Zejma; N. Ziehl; G. Zsigmond

arXiv · 2511.06884

Ultracold neutron energy spectrum and storage properties from magnetically induced spin depolarization

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Abstract

We present a novel method for extracting the energy spectrum of ultracold neutrons from magnetically induced spin depolarization measurements using the n2EDM apparatus. This method is also sensitive to the storage properties of the materials used to trap ultracold neutrons, specifically, whether collisions are specular or diffuse. We highlight the sensitivity of this new technique by comparing the two different storage chambers of the n2EDM experiment. We validate the extraction by comparing to an independent measurement for how this energy spectrum is polarized through a magnetic-filter, and finally, we calculate the neutron center-of-mass offset, an important systematic effect for measurements of the neutron electric dipole moment.

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N. J. Ayres, G. Ban, G. Bison, K. Bodek, V. Bondar, T. Bouillaud, D. Bowles, G. L. Caratsch, E. Chanel, W. Chen, P. -J. Chiu, C. B. Crawford, V. Czamler, M. Daum, C. B. Doorenbos, M. Ferry, M. Fertl, A. Fratangelo, D. Galbinski, W. C. Griffith, Z. D. Grujic, K. Kirch, V. Kletzl, B. Lauss, T. Lefort, A. Lejuez, R. Li, K. Michielsen, J. Micko, P. Mullan, A. Mullins, O. Naviliat-Cuncic, D. Pais, F. M. Piegsa, G. Pignol, C. Pistillo, D. Rebreyend, I. Rienäcker, D. Ries, S. Roccia, D. Rozpedzik, W. Saenz-Arevalo, L. Sanchez-Real Zielniewicz, P. Schmidt-Wellenburg, E. P. Segarra, L. Segner, N. Severijns, K. Svirina, K. S. Tanaka, J. Thorne, J. Vankeirsbilck, N. von Schickh, N. Yazdandoost, J. Zejma, N. Ziehl, G. Zsigmond. 2025-11-10. Ultracold neutron energy spectrum and storage properties from magnetically induced spin depolarization. https://arxiv.org/abs/2511.06884

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