7-Member NEMESIS Team Arrives at Sanford Underground Research Facility

Q: What mystery from Finland is NEMESIS trying to test at SURF, and could comparing two depths reveal unknown neutron sources or new physics?

NEMESIS is testing an anomaly first seen in earlier underground measurements at the Pyhäsalmi mine in Finland: unexpectedly puzzling high neutron multiplicity events, in which cosmic-ray muons appear to trigger bursts of many neutrons. Those neutron showers matter because they can imitate or obscure the rare signals sought by dark-matter, neutrino and other low-background experiments. At SURF, the collaboration is trying to determine whether the Finnish anomaly is simply an incompletely understood background or evidence of something more unusual. The leading conventional explanation is muon-induced neutron production in surrounding rock or shielding materials, but the team has also said the excess could point to a previously uncharacterized neutron source. In the most speculative case, it could hint at new physics, including an indirect dark-matter-related effect. The key test is depth. NEMESIS has been installed at SURF’s 4850 Level and the team hopes to add a second station at the 1700 Level. Because cosmic-ray muon flux changes strongly with depth, comparing twin detector systems at two levels should show whether the neutron events scale the way known physics predicts. If the rates and characteristics match expectations, the Finnish mystery likely reflects ordinary underground backgrounds. If they do not, that would strengthen the case for an unknown neutron source—or, less likely, new physics.

1 articles · Updated · Black Hills Pioneer · Jul 29

Seven NEMESIS installation team members reached the Sanford Underground Research Facility, marking the collaboration’s arrival at the deep underground lab.
SURF released photos identifying team members including Frederick Shuckman, Brianna Mount, Katie Pedneau, Harkirat Riyat, Doug Tiedt, Alex Barzilov and Wladyslaw Trzaska.
A separate arrival photo also showed Alexander Barzilov, Thomas Ward and Wladyslaw Trzaska at the South Dakota research site.
The report framed NEMESIS as a scientific project at SURF, despite the experiment’s dramatic name evoking science-fiction imagery.

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Black Hills Pioneer25d ago

NEMESIS Collaboration Arrives at Sanford Underground Research Facility (SURF)

What mystery from Finland is NEMESIS trying to test at SURF, and could comparing two depths reveal unknown neutron sources or new physics?

How will NEMESIS at SURF measure cosmic-ray-driven neutron bursts, and why do those backgrounds matter so much for ultra-sensitive underground detectors?

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1 total

Black Hills Pioneer25d ago

NEMESIS Collaboration Arrives at Sanford Underground Research Facility (SURF)

7-Member NEMESIS Team Arrives at Sanford Underground Research Facility

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