Extending the reach of axion-photon regeneration experiments towards larger masses with phase shift plates

Abstract

We present a scheme to extend the sensitivity of axion-photon regeneration experiments towards larger masses with the help of properly chosen and placed phase shift plates.

Figures (7)

• Figure 1: Schematic view of ALP production through photon conversion in a magnetic field (left), subsequent travel through an optical barrier, and final detection through photon regeneration (right).
• Figure 2: Two photon coupling $g$ of the (pseudo-)scalar versus its mass $m_\phi$. Iso-contour of the regeneration probability $P_{\gamma\to\phi\to\gamma}=P_{\gamma\to\phi}P_{\phi\to\gamma}$, for the parameters of the ALPS experiment, i.e. magnetic fields $B_1=B_2=5$ T, over a length $\ell_1=\ell_2=4.21$ m, exploiting a green ($\lambda =532$ nm) photon beam, corresponding to $\omega = 2.34$ eV, in vacuum. Also shown in red are the 5 sigma allowed regions Ahlers:2006iz from PVLAS data on rotation Zavattini:2005tm plus BFRT data on rotation, ellipticity, and regeneration Cameron:1993mr plus Q&A data on rotation Chen:2006cd.
• Figure 3: Iso-contour of the regeneration probability, as in Fig. \ref{['regprop_stan']}, but with reduced lengths of the magnetic field region. Note, that the regeneration probability is reduced by a factor of $10$.
• Figure 4: Iso-contour of the regeneration probability, as in Fig. \ref{['regprop_stan']}. Here, we used one phase shift ("$\lambda/2$") plate each in the middle of the generation and the regeneration sides.
• Figure 5: Illustration of the effect of a properly chosen and placed phase shift plate on the phase relation between photon and ALP (this simplified picture shows only the phase relation; the amplitudes of photon and ALP are not correct in this picture). Photon (red) and ALP (black) start in phase. Due to their different wavelength they are, however, somewhat out of phase after several oscillations - say by an amount $\zeta$. This is corrected by introduction of a phase shift plate that causes the photon to get an extra phase $2\pi-\zeta$. In other words the plate causes the photon to complete the extra wiggle.