University of Oulu

Trzaska, W. H., Barzilov, A., 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., & Ward, T. E. (2022). Nemesis setup for indirect detection of wimps. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 1040, 167223.

NEMESIS setup for Indirect Detection of WIMPs

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Author: Trzaska, W. H.1,2; Barzilov, A.3; Enqvist, T.1;
Organizations: 1Department of Physics, University of Jyväskylä, P.O. Box 35, FI-40014 University of Jyväskylä, Finland
2Helsinki Institute of Physics (HIP), University of Helsinki, P.O. Box 64, FI-00014 University of Helsinki, Finland
3University of Nevada Las Vegas, Department of Mechanical Engineering, Nevada 89154-4027, United States
4Cosmic Ray Laboratory, National Centre for Nuclear Research (NCBJ), 28 Pulku Strzelcow Kaniowskich 69, PL-90558 Lodz, Poland
5University of Oulu, Kerttu Saalasti Institute, Pajatie 5, FI-85500 Nivala, Finland
6Institut für Physik (IPH), Johannes Gutenberg-Universität Mainz (JGU), Staudingerweg 7, DE-55128 Mainz, Germany
7University of Oulu, Sodankylä Geophysical Observatory, P.O. Box 3000, FI-99600 Sodankylä, Finland
8Office of Nuclear Energy, DOE 1000 Independence Ave., 20585, Washington D.C., United States
9TechSource, Santa Fe, NM, United States
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 1.3 MB)
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Language: English
Published: Elsevier, 2022
Publish Date: 2023-02-14


We summarize the evidence for DM-like anomalies in neutron multiplicity spectra collected underground with Pb targets by three independent experiments: NEMESIS (at 210 m.w.e.) NMDS (at 583 m.w.e.), and ZEPLIN-II (at 2850 m.w.e.). A new analysis shows small but persistent anomalies at high neutron multiplicities. Adjusted for differences in detection efficiencies, the positions of the anomalies are consistent between the three systems. Also, the intensities match when corrected for the acquisition time and estimated detection efficiency. While the three measurements are inconclusive when analyzed separately, together, they exclude a statistical fluke to better than one in a million. To prove the existence of the anomalies above the 5-sigma discovery threshold, we propose to upgrade the current NEMESIS setup. The upgrade concept and the critical components of the new experiment are described. The upgraded setup would already acquire the needed data sample during the first year of operation. Additional information, vital for the physics interpretation of the analysis, will be obtained with a Cu target.

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Series: Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment
ISSN: 0168-9002
ISSN-E: 1872-9576
ISSN-L: 0168-9002
Volume: 1040
Article number: 167223
DOI: 10.1016/j.nima.2022.167223
Type of Publication: A1 Journal article – refereed
Field of Science: 115 Astronomy and space science
Funding: This work has been supported in part by the EU INTERREG for the Baltic Sea programme within the BSUIN project and by the Polish Ministry of Science and Higher Education (Grant no. 3988/INTERREG BSR/2018/2). Assistance from A. Sobkow from the Lodz University of Technology is gratefully acknowledged.
Copyright information: © 2022 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY license (