@article{776fdf66eff5474aa070608c07bdc752,
title = "Probing neutron-hidden neutron transitions with the MURMUR experiment",
abstract = " MURMUR is a new passing-through-walls neutron experiment designed to constrain neutron/hidden neutron transitions allowed in the context of braneworld scenarios or mirror matter models. A nuclear reactor can act as a hidden neutron source, such that neutrons travel through a hidden world or sector. Hidden neutrons can propagate out of the nuclear core and far beyond the biological shielding. However, hidden neutrons can weakly interact with usual matter, making possible for their detection in the context of low-noise measurements. In the present work, the novelty rests on a better background discrimination and the use of a mass of a material - here lead - able to enhance regeneration of hidden neutrons into visible ones to improve detection. The input of this new setup is studied using both modelizations and experiments, thanks to tests currently performed with the experiment at the BR2 research nuclear reactor (SCK$\cdot$CEN, Mol, Belgium). A new limit on the neutron swapping probability p has been derived thanks to the measurements taken during the BR2 Cycle 02/2019A: $p <4.0 \ \times 10^{-10}$ at 95% CL. This constraint is better than the bound from the previous passing-through-wall neutron experiment made at ILL in 2015, despite BR2 is less efficient to generate hidden neutrons by a factor 7.4, thus raising the interest of such experiment using regenerating materials. ",
keywords = "nucl-ex, hep-ex, hep-ph, physics.ins-det",
author = "C. Stasser and G. Terwagne and J. Lamblin and O. M{\'e}plan and G. Pignol and B. Coup{\'e} and S. Kalcheva and Dyck, {S. Van} and M. Sarrazin",
note = "Funding Information: The authors wish to acknowledge, posthumously, Edgar Koonen, former BR2 Deputy Reactor Manager, passed away in 2017. His enthusiasm for our work allowed us to initiate the MURMUR collaboration. C.S., G.T. and M.S. acknowledge Louis Lambotte, Tijani Tabarrant and Alexandre Felten for technical support. The authors are grateful to Wim De Vocht and Nico Segers for their help during the installation of the experiment at the BR2 and for their technical support. This work is supported by the Department of Physics of the University of Namur. C.S. is supported by a FRIA doctoral grant from the Belgian F.R.S.-FNRS. M.S., PI of the MURMUR collaboration, acknowledges the University of Namur to host and support the project. Funding Information: The authors wish to acknowledge, posthumously, Edgar Koonen, former BR2 Deputy Reactor Manager, passed away in 2017. His enthusiasm for our work allowed us to initiate the MURMUR collaboration. C.S., G.T. and M.S. acknowledge Louis Lambotte, Tijani Tabarrant and Alexandre Felten for technical support. The authors are grateful to Wim De Vocht and Nico Segers for their help during the installation of the experiment at the BR2 and for their technical support. This work is supported by the Department of Physics of the University of Namur. C.S. is supported by a FRIA doctoral grant from the Belgian F.R.S.-FNRS. M.S., PI of the MURMUR collaboration, acknowledges the University of Namur to host and support the project. Publisher Copyright: {\textcopyright} 2021, The Author(s).",
year = "2021",
month = jan,
day = "1",
doi = "10.1140/epjc/s10052-021-08829-y",
language = "English",
volume = "81",
journal = "European Physical Journal C",
issn = "1434-6044",
publisher = "Springer New York",
number = "1",
}