First Results from Dark Matter Search Experiment in the Nokogiriyama Underground Cell

TL;DR

This paper reports initial results from a dark matter search experiment using a cryogenic bolometer array at a shallow underground site, setting new limits on light neutralino interactions.

Contribution

First experimental results from a cryogenic bolometer dark matter search at Nokogiriyama, improving sensitivity for light neutralinos below 5 GeV.

Findings

Set new exclusion limits for neutralino-proton cross section.

Improved sensitivity for neutralino masses below 5 GeV.

Demonstrated feasibility of shallow underground dark matter detection.

Abstract

An experiment to search for hypothetical particle dark matter using cryogenic thermal detector, or bolometer is ongoing. The bolometer consists of eight pieces of 21 g LiF absorbers and sensitive NTD germanium thermistors attached to them and is installed in the Nokogiriyama underground cell which is a shallow depth site ($\sim 15$ m w.e.). We report on the results from the first running for about ten days using this arrayed bolometer system together with appropriate shieldings and muon veto counters. From the obtained energy spectra the exclusion limits for the cross section of the elastic neutralino-proton scattering are derived under commonly accepted astrophysical assumptions. The sensitivity for the light neutralino with a mass below 5 GeV is improved by this work.