Open AccessThe PVLAS experiment: detecting vacuum magnetic birefringence
Author(s) -
G. Zavattini,
F. Della Valle,
U. Gastaldi,
G. Messineo,
E. Milotti,
R. Pengo,
L. Piemontese,
G. Ruoso
Publication year - 2013
Publication title -
journal of physics. conference series
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.21
H-Index - 85
eISSN - 1742-6596
pISSN - 1742-6588
DOI - 10.1088/1742-6596/442/1/012057
Subject(s) - birefringence , materials science , nuclear magnetic resonance , optics , physics
The PVLAS collaboration is presently assembling a new apparatus to detect vacuum magnetic birefringence. This property is related to the structure of the QED vacuum and is predicted by the Euler-Heisenberg-Weisskopf effective Lagrangian. It can be detected by measuring the ellipticity acquired by a linearly polarised light beam propagating through a strong magnetic field. Here we report results of a scaled-down test setup and briefly describe the new PVLAS apparatus. This latter one is in construction and is based on a high-sensitivity ellipsometer with a high-finesse Fabry-Perot cavity $(> 4\times10^5)$ and two 0.8 m long 2.5 T rotating permanent dipole magnets. Measurements with the test setup have improved by a factor 2 the previous upper bound on the parameter $A_e$, which determines the strength of the nonlinear terms in the QED Lagrangian: $A^{\rm (PVLAS)}_e < 3.3 \times10^{21}~{\rm T}^{-2}$ 95\% c.l