Improved constraints on WIMPs from the International Germanium Experiment IGEX

TL;DR

This paper presents new constraints on WIMP dark matter particles using data from the IGEX germanium detector, improving previous limits and challenging the DAMA experiment's claimed detection region.

Contribution

It provides the first exclusion limits from IGEX data that enter the DAMA region without background discrimination, using only raw data.

Findings

IGEX data improves WIMP-nucleon interaction limits in 20-200 GeV mass range.

The new exclusion contour overlaps with the DAMA region, excluding part of it.

Moderate detector improvements could fully explore the DAMA region.

Abstract

One IGEX 76Ge double-beta decay detector is currently operating in the Canfranc Underground Laboratory in a search for dark matter WIMPs, through the Ge nuclear recoil produced by the WIMP elastic scattering. A new exclusion plot, has been derived for WIMP-nucleon spin-independent interactions. To obtain this result, 40 days of data from the IGEX detector (energy threshold E \~ 4 keV), recently collected, have been analyzed. These data improve the exclusion limits derived from all the other ionization germanium detectors in the mass region from 20 GeV to 200 GeV, where a WIMP supposedly responsible for the annual modulation effect reported by the DAMA experiment would be located. The new IGEX exclusion contour enters, by the first time, the DAMA region by using only raw data, with no background discrimination, and excludes its upper left part. It is also shown that with a moderate improvement of the detector performances, the DAMA region could be fully explored.