Magnetic birefringence of the vacuum due to electron-positron pairs remains to be measured as one of the fundamental tests of QED.
It has been predicted about 80 years ago but not experimentally measured.
To make the QED effect large, a high magnetic length is preferable.
Precision setups like PVLAS (Ferrara), BMV (Toulouse) and OSQAR (CERN) are aiming to measure this fascinating effect. So far a limiting factor is high noise. Experimental progress made in 2015 might be decisive for future efforts.
On the other hand the ALPS-II experiment at DESY is primarily conceived to find axion-like particles. The experiment is currently being set up in a 10m configuration without magnets but we are entering a phase in which more detailed planning of the magnet string is imminent.
In principle, the huge magnetic length of (B^2 L) of ALPS-II of about 2480 T^2m would suggest itself also for a measurement of QED vacuum magnetic birefringence. The technical feasibility of this measurement at DESY is however less clear. Albeit a proposal at FERMILAB 877 aimed to measure this effect with superconducting dipole magnets was put forward but was never performed.
The idea of this workshop is thus to have a small number of experts in vacuum magnetic birefringence measurements invited with a limited number of contributed talks.
In addition, there will be a public talk (in German) on the 2nd of november by Holger Gies: http://fortbildung.desy.de/e109/e187998/e204744/
If you want to contribute a talk, please get in touch with the main organizers.
It has been predicted about 80 years ago but not experimentally measured.
To make the QED effect large, a high magnetic length is preferable.
Precision setups like PVLAS (Ferrara), BMV (Toulouse) and OSQAR (CERN) are aiming to measure this fascinating effect. So far a limiting factor is high noise. Experimental progress made in 2015 might be decisive for future efforts.
On the other hand the ALPS-II experiment at DESY is primarily conceived to find axion-like particles. The experiment is currently being set up in a 10m configuration without magnets but we are entering a phase in which more detailed planning of the magnet string is imminent.
In principle, the huge magnetic length of (B^2 L) of ALPS-II of about 2480 T^2m would suggest itself also for a measurement of QED vacuum magnetic birefringence. The technical feasibility of this measurement at DESY is however less clear. Albeit a proposal at FERMILAB 877 aimed to measure this effect with superconducting dipole magnets was put forward but was never performed.
The idea of this workshop is thus to have a small number of experts in vacuum magnetic birefringence measurements invited with a limited number of contributed talks.
In addition, there will be a public talk (in German) on the 2nd of november by Holger Gies: http://fortbildung.desy.de/e109/e187998/e204744/
If you want to contribute a talk, please get in touch with the main organizers.
The main objective of this workshop will be to discuss results and limitations of the ongoing birefringence measurements in different configurations
and their potential applicability for a potential QED setup at the ALPS-II magnet string.
This workshop is sponsored by PIER https://www.pier-hamburg.de/
and organized by
Main organizers: Babette Döbrich (CERN) and Jan Pold (DESY)
Advisory: G. Moortgart-Pick, A.Lindner, A.Ringwald (DESY), R.Schnabel (Univ. Hamburg)
