Axion Dark Matter Detection Using Atomic Transitions

Dark matter axions may cause transitions between atomic states that differ in energy by an amount equal to the axion mass. Such energy differences are conveniently tuned using the Zeeman effect. It is proposed to search for dark matter axions by cooling a kilogram-sized sample to millikelvin temperatures and count axion induced transitions using laser techniques. This appears to be an appropriate approach to axion dark matter detection in the $10^{-4}\mathrm{eV}$ mass range.

Figure 1

Expected sensitivity of the proposed detector to the coupling of the axion to electrons. The diagonal lines are the predictions of models with $g_e=1.0$ and 0.3. The vertical line on the right is an upper bound on the axion mass from supernova SN1987a. The solid horizontal line is an upper limit on the coupling from the white dwarf cooling rate. The horizontal dotted line is the value of the coupling that yields a best fit to the white dwarf cooling observations. The shaded area indicates the expected sensitivity of the proposed detector under the assumptions spelled out in the text, using electron paramagnetic resonance (dark) and antiferromagnetic resonance (light)

Figure 2

Expected sensitivity of the proposed detector to the coupling of the axion to nuclei. The diagonal lines are the couplings when $g_N=1.0$ and 0.3. The horizontal line near the top is the upper bound on the coupling from supernova SN1987a, for $g_N=1$. The shaded area indicates the expected sensitivity of the proposed detector under the assumptions spelled out in the text.