Speaker
Stepan Kunc
(Technical University of Liberec)
Description
Vacuum magnetic birefringence is a non-linear electrodynamic effect predicted as a consequence of the formulation of the Euler-Kockel-Heisenberg effective Lagrangian, first proposed in 1935, which takes into account electron-positron fluctuations. A direct laboratory observation of vacuum magnetic birefringence is still lacking today due to its value: ∆n = 4x10e-24 @ B = 1T.
Key ingredients of a polarimeter for detecting such a small birefringence are a long optical path within an intense magnetic field and a time-dependent effect. To lengthen the optical path a Fabry-Perot cavity is generally used. Interestingly, there is a difficulty in reaching the predicted shot noise limit of such polarimeters: the cavity mirrors generate a birefringence-dominated noise whose ellipticity is amplified by the cavity itself limiting the maximum finesse capable of increasing the SNR.
The VMB@CERN collaboration proposes an experiment which overcomes this difficulty by using an LHC superconducting magnet together with a novel polarization modulation scheme for the polarimeter.
Primary author
Stepan Kunc
(Technical University of Liberec)
Co-authors
Dr
A. Ellji
(3School of Physics and Astronomy, Cardiff University)
Dr
F. Della Valle
(2INFN, Sez. di Trieste and Dip. di Fisica, Università di Trieste)
Dr
G. Ruoso
(3INFN, Lab. Naz. di Legnaro, viale dell’Università)
Prof.
G. Zavattini
(Università di Ferrara and INFN)
Dr
M. Sulc
(Technical University of Liberec)
Dr
P. Pugnat
(11LNCMI, EMFL, CNRS & Université Grenoble Alpes)
