Mötesplats Rydberg - Valentina Santoro (ESS), "Search for free Neutron Oscillations at the European Spallation Source"

Tuesday 31 May 2022, 15:00 → 16:00 Europe/Stockholm

Rydberg hall

Abstract: "The 2020 Update for the European Strategy for Particle Physics explicitly highlights the need for programs at the so-called intensity frontier at other European laboratories together with the energy frontier research at CERN. The European Spallation Source ESS, presently under construction, in Lund, Sweden, is a multi-disciplinary international laboratory that will operate the world's most powerful pulsed neutron source.

Taking advantage of this unique potential of the ESS, the NNBAR collaboration proposed a two-stage program of experiments to perform high precision searches for neutron conversion in a range of baryon number violation channels culminating in an ultimate sensitivity increase for n → n ̅ oscillations of three orders of magnitude over the previously attained limit obtained at the Institut Laue-Langevin ILL [1]. The observation of BNV via free neutron oscillations would be of fundamental discovery, with implications for many unanswered questions in physics which include the origin of the matter-antimatter asymmetry and the origin of neutrino mass.

The first stage of this program HIBEAM (High Intensity Baryon Extraction and Measurement) will make use of the ESS fundamental physics beamline.  This stage focuses principally on searches for neutron conversion to sterile neutrons n' [2] that would belong (o be related) to a “dark” sector.

The second stage, NNBAR, will exploit a large beam port, specifically designed for this experiment in the ESS target station monolith to maximize the neutron flux and search directly for n → n ̅ oscillations. The NNBAR experiment would take neutrons produced from the ESS source which would then be reflected and focused through a magnetic field-free region towards a distant carbon target. The target is surrounded by a detector to observe a baryon number annihilation signal of an antineutron with a nucleon in a carbon nucleus. The signature produced by this process is a multipion final state with invariant mass near 1.9 GeV. To identify such signature a detector including tracking and calorimetry is being designed with the aid of Geant4.

The HIBEAM/NNBAR collaboration is currently working on the HIBEAM Technical Design report supported by the Swedish Research Council and to the Conceptual Design report for the NNBAR supported by the European Commission This talk will focus on the on-going developments both for the HIBEAM and the NNBAR experiment."

[1] M. Baldo-Ceolin, et al., A New experimental limit on neutron - anti-neutron oscillations, Z. Phys. C 63 (1994) 409–416. doi:10.1007/BF01580321

[2] Z. Berezhiani and L. Bento, “Neutron - mirror neutron oscillations: How fast might they be?,” Phys. Rev. Lett. 96 (2006) 081801, arXiv:hep-ph/0507031 [hep-ph].

The meeting is held in the Rydberg lecture hall with the possibility to join digitally: https://lu-se.zoom.us/j/910953381

RydbergSeminar.pptx