A4 Article in conference proceedings
DM-like anomalies in neutron multiplicity spectra (2021)

Trzaska, W. H., Enqvist, T., Jedrzejczak, K., Joutsenvaara, J., Kasztelan, M., Kotavaara, O., Kuusiniemi, P., Loo, K.K., Orzechowski, J., Puputti, J., Slupecki, M., Szabelski, J., Usoskin, I., & Warda, T.E. (2021). DM-like anomalies in neutron multiplicity spectra. In TAUP 2021 : 17th International Conference on Topics in Astroparticle and Underground Physics (2156, Article 012029). IOP Publishing. Journal of Physics : Conference Series. https://doi.org/10.1088/1742-6596/2156/1/012029

JYU authors or editors

Publication details

All authors or editors: Trzaska, W. H.; Enqvist, T.; Jedrzejczak, K.; Joutsenvaara, J.; Kasztelan, M.; Kotavaara, O.; Kuusiniemi, P.; Loo, K.K.; Orzechowski, J.; Puputti, J.; et al.

Parent publication: TAUP 2021 : 17th International Conference on Topics in Astroparticle and Underground Physics

Place and date of conference: Online, 26.8.-3.9.2021

Journal or series: Journal of Physics : Conference Series

ISSN: 1742-6588

eISSN: 1742-6596

Publication year: 2021

Publication date: 01/12/2021

Volume: 2156

Article number: 012029

Publisher: IOP Publishing

Publication country: United Kingdom

Publication language: English

DOI: https://doi.org/10.1088/1742-6596/2156/1/012029

Publication open access: Openly available

Publication channel open access: Open Access channel

Publication is parallel published (JYX): https://jyx.jyu.fi/handle/123456789/80033

Abstract

A new experiment collects data, since November 2019, at a depth of 210 m.w.e. in the Callio Lab in the Pyhasalmi mine in Finland. The setup, called NEMESIS (New Emma MEasurementS Including neutronS), incorporates infrastructure from the EMMA experiment with neutron and large-area plastic scintillator detectors. The experiment's primary aim is to combine muon tracking with position-sensitive neutron detection to measure precision yields, multiplicities, and lateral distributions of high-multiplicity neutron events induced by cosmic muons in various materials. The data are relevant for background evaluation of the deep underground searches for Dark Matter (DM), neutrino-less double beta decay, etc. Preliminary analysis revealed anomalies in muon-suppressed neutron multiplicity spectra collected during a 344-day run (live time) with a 565 kg Pb target. The spectra, otherwise well described by an exponential fit, show three peaks at high multiplicities. Although still at a low statistical significance, these small excesses match the outcome of an earlier measurement. The nature of the anomalies remains unclear, but, in principle, they may be a signature of self-annihilation of a WIMP with a mass close to 13 GeV/c2 . With that assumption, the expected cross-section would be around 10-42 cm2 for Spin-Dependent or 10-46 cm2 for Spin Independent interactions. We propose verifying this hypothesis with an upgraded NEMESIS experiment, able to collect an order of magnitude more data than this measurement. Based on the statistical uncertainty, analysis of the event rate indicates that cross-section limits for DM mass range of approximately 3-40 GeV/c2 can be investigated with such a setup.

Keywords: particle physics; detectors; neutrons; dark matter

Contributing organizations

Ministry reporting: Yes

Reporting Year: 2021

JUFO rating: 1