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Search for Galactic <strong>Axion</strong>s (Cold Dark Matter)<br />
Georg Raffelt, Max-Planck-Institut für Physik, München, Germany<br />
PONT d‘Avignon, 21-25 April 2008, Avignon, France<br />
DM axions<br />
m a = 1-10001<br />
1000 μeV<br />
Velocities in galaxy<br />
v a ≈ 10 −3 c<br />
Energies therefore<br />
E a ≈ (1 ± 10 −6 ) m a<br />
Microwave Energies<br />
(1 GHz ≈ 4 μeV)<br />
<strong>Axion</strong> Haloscope (Sikivie 1983)<br />
B ext ≈ 8 Tesla<br />
Microwave<br />
Resonator<br />
Q ≈ 10 5<br />
Power<br />
Frequency<br />
m a<br />
<strong>Axion</strong> Signal<br />
Thermal noise of<br />
cavity & detector<br />
Primakoff Conversion<br />
a<br />
γ<br />
B ext<br />
Cavity<br />
overcomes<br />
momentum<br />
mismatch<br />
Power of galactic axion signal<br />
2<br />
×<br />
−21<br />
V ⎛ B ⎞ Q<br />
4 10<br />
W<br />
3<br />
⎜ ⎟<br />
⎝ 8.5T ⎠ 5<br />
0.22m 10<br />
⎛<br />
m<br />
⎞⎛<br />
× ⎜ a ⎟<br />
⎜<br />
⎝<br />
2<br />
π<br />
GHz<br />
⎠<br />
⎝<br />
5<br />
×<br />
10<br />
ρ<br />
a<br />
−<br />
25<br />
g/cm<br />
3<br />
⎞<br />
⎟<br />
⎠
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