On the trapping of neutrons in Fabry–Pérot nano-structures and potential applications for cold neutron lifetime Investigations

Article type: Research Article

Authors: Maaza, M.^{a; b; *} | Pardo, B.^{c; †} | Hamidi, D.^{a; b} | Akbari, M.^{a; b} | Morad, R.^{a; b} | Henini, M.^{a; b; d} | Gibaud, A.^{a; b; e}

Affiliations: [a] UNESCO-UNISA Africa Chair in Nanosciences-Nanotechnology, University of South Africa, PO Box 392, Pretoria, South Africa | [b] Nanosciences African Network (NANOAFNET), iThemba Laboratories for Accelerators Based Sciences, iThemba LABS-National Research Foundation, PO Box 722, Somerset West, Western Cape Province, South Africa | [c] Institut d’Optique Théorique & Appliquée, Université Paris-Saclay, France | [d] Physics Department, University of Nottingham, Nottingham, UK | [e] IMMM, UMR 6283 CNRS, Université of Le Maine, Bd O. Messiaen, 72085 Le Mans cedex 09, Le Mans, France

Correspondence: [*] Corresponding author. E-mail: Maaza@tlabs.ac.za.

Note: [†] Deceased.

Abstract: Correlated to the neutron total reflection phenomenon is the so-called frustrated total reflection, also known as neutron channeling, observed with both thermal and cold neutrons. Within this contribution, such a phenomenon is validated in various additional distinctive Fabry–Pérot nano-resonating configurations; namely in: (i) dual reflection and transmission neutron Fabry–Pérot nano-resonator (Ni/V/Ni/Si substrate), (ii) isotope-based neutron Fabry–Pérot nano-resonator (58Ni/62Ni/58Ni/Silicon substrate), and (iii) multilayered neutron Fabry–Pérot nano-resonator of 8 superposed (B4C/Ti/B4C) single nano-resonators. While such Fabry–Pérot nano-resonators allow effective neutron trapping, the precision of the trapping time of free neutrons in such nano-resonators is governed by the Heisenberg uncertainty and hence offers, a priori, an additional attractive precise approach for potential lifetime investigations. Depending on the configuration of the Fabry–Pérot nano-resonators and the available cold neutron beam, the trapping time is found to be within the temporal regime of 3 to 19 ps. While the main intention of this contribution is to validate the possibility of trapping cold neutrons in nano-structured Fabry–Pérot resonators with a picosecond precision in various configurations, it is hoped that these preliminary results will attract the interest of the neutron lifetime community specifically and the neutron scattering community in general. The potential integration of such trapping method into the bottle or beam methods would elucidate the origin of the difference in neutron lifetime between the two approaches.

Keywords: Neutron trapping, Fabry–Pérot nano-resonators, frustrated total reflection, neutron waveguiding, neutron lifetime, total reflection, Zeldovich–Vinogradov configuration, B₄C, Fermi pseudo-potential

DOI: 10.3233/JNR-220015

Journal: Journal of Neutron Research, vol. 25, no. 1, pp. 13-28, 2023