Search for Axions with the CDMS Experiment

We report on the first axion search results from the Cryogenic Dark Matter Search (CDMS) experiment at the Soudan Underground Laboratory. An energy threshold of 2 keV for electron-recoil events allows a search for possible solar axion conversion into photons or local galactic axion conversion into electrons in the germanium crystal detectors. The solar axion search sets an upper limit on the Primakov coupling $g_{a\gamma \gamma }$ of $2.4\times {10}^{-9}{\mathrm{GeV}}^{-1}$ at the 95% confidence level for an axion mass less than $0.1\mathrm{keV}/c^2$. This limit benefits from the first precise measurement of the absolute crystal plane orientations in this type of experiment. The galactic axion search analysis sets a world-leading experimental upper limit on the axioelectric coupling $g_{a\overline{e}e}$ of $1.4\times {10}^{-12}$ at the 90% confidence level for an axion mass of $2.5\mathrm{keV}/c^2$.

Figure 1

Time and energy dependence of the expected solar axion conversion rate in a Ge detector for $g_{a\gamma \gamma }={10}^{-8}{\mathrm{GeV}}^{-1}$.

Figure 2

Detection efficiency as a function of energy.

Figure 3

Coadded, efficiency corrected low energy spectrum of the Ge detectors considered in this analysis. The inset shows an enlargement of the spectrum in the analysis window, taken to be 2–8.5 keV.

Figure 4

Comparison of the 95% C.L. upper limit on $g_{a\gamma \gamma }$ achieved in this analysis (red solid line) with other crystal search experiments (SOLAX and COSME [15, 16] (black solid line) and DAMA (upper black dashed line) [17]) and helioscopes [Tokyo helioscope (magenta solid line) [21] and CAST (blue solid line) 11]. The indirect constraint of pseudoscalar from solar neutrino flux bound is also shown [22].

Figure 5

The 90% C.L. upper limit on the $g_{a\overline{e}e}$ coupling constant from this work (red solid line) is shown together with the constraint from CoGeNT experiment (blue solid line) [23]. The indirect constraint of pseudoscalar from solar neutrino bound (black dashed line) [24] is shown as well. The allowed region (green filled region) from a galactic axion interpretation claimed by the DAMA experiment [18] is shown for comparison.