Post on 02-Jan-2016
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The OSQAR experiments at CERN
and a new axion↔photon converter using quadrupole magnetic field
Krzysztof A. MeissnerUniversity of Warsaw
• The OSQAR experiments at CERN for low energy aser-based Particle/Astroparticle Physics (abstract #48, OSQAR Coll.)
• Use an LHC quadrupole magnet as axion ↔ photon converter (abstract #71, A. Siemko and K. Zioutas)
CERN, 12.05.2009, New Opportunities...
Outline
Optical Search for QED vacuum magnetic birefringence, Axions
& photon Regeneration
Optical Search for QEDvacuum magnetic birefringenceAxion and photon Regeneration
Laser-based Particle/Astroparticle Physics Experiments at CERN To Test QED & Explore the Low Energy Frontier…
The Collaboration ► 22 Members from 9 Institutes (CZ, F, PL & CERN)
Charles University
Universityof Warsaw
CTU
Motivations
Optical Search for QEDvacuum magnetic birefringenceAxion and photon Regeneration
To measure for the first time the Vacuum Magnetic Birefringence predicted in QED
(Heisenberg & Euler, Weisskopf, 1936) i.e. the vacuum magnetic “anomaly” of the refraction index “ n-1” ~ 10-22 in 9.5 T
• The effective lagrangian for photons in QED has nonlinear terms
L=(E2-B2)/2 (ε0=1,μ0=1)
-α (E•∆E - B•∆B) /(30πm2)
+2α2((E2-B2) 2+7(E•B) 2) /(45 m4)+…• The QED light-on-light scattering produces ellipticity in the linearly
polarized light travelling in the magnetic field
Ψ = α2 ωlB2sin(2θ) /(15 m4) (~ 10 -11rad for OSQAR)
The OSQAR Experiments @ CERN For Low Energy Laser-based Particle/Astroparticle Physics
Motivations
Optical Search for QEDvacuum magnetic birefringenceAxion and photon Regeneration
2. To discover axions– axions solve the strong CP problem (Weinberg, Wilczek, 1978)
– they are non-SUSY Cold Dark Matter candidates
(Abbott & Sikivie; Preskill, Wise & Wilczek, 1983)
– coupling to photons
L = g a E • B– the coupling induces rotation of polarization and ellipticity for light
propagation in the magnetic field (Sikivie 1983,1985,…)
– ,,Shining through the wall’’ experiment –
(laser photon → axion) wall (axion → photon) detection
– the experiment puts bounds on couplings of paraphotons, milli-charged fermions, chameleons,...
The OSQAR Experiments @ CERN For Low Energy Laser-based Particle/Astroparticle Physics
Basic Principles of the Experiments
Optical Search for QEDvacuum magnetic birefringenceAxion and photon Regeneration
Optical Search for QED
vacuum magnetic birefringence
Axion and photon Regeneration
► In one aperture of dipole-1, measurement of the Vacuum Magnetic Birefringence & Dichroïsm
► In the 2nd aperture of dipole-1 & one aperture of dipole-2, Photon Regeneration Experiment
x
a
9.5 T
x
~ 53 m
The OSQAR Experiments @ CERN For Low Energy Laser-based Particle/Astroparticle Physics
LN2 cooled CCD
Use of 2 LHC cryo-dipoles (double apertures) for Phase-1&2
The OSQAR Experiments @ CERN For Low Energy Laser-based Particle/Astroparticle Physics
Experiments - Expected results - Short & “Long” Term
Perspectives
PVLAS, PRL 96 (2006)
CAST-2003, PRL 94(2005)
Expectation VMB Without Upgrades*
Expect. from Regeneration Experiment
From C. Hagmann, K. van Bibber, L.J. Rosenberg, Physics Lett. B, vol.592, 2004
Expected 2009
Optical Search for QEDvacuum magnetic birefringenceAxion and photon Regeneration
• Photon regeneration Experiment
- Preliminary Phase to test PVLAS results; 1 dipole with/without gas (done) * *
- Phase-1 : 2 dipoles, CW laser beam, extra & intra cavity to improve BFRT/GammeV results (2009-2010)
- Phase-2 : 2 dipoles, CW laser beam & High Finesse FP cavity (2011-2012)
- Phase-3 : more than 2 dipoles to reach astrophysical bounds
• “n-1 Experiment” i.e. VMB & Linear Dichroism
- Phase-1&2 : Measurements of QED prediction in O(2) & O(3)
- within 1 dipole (2013 & 2014)
*P. Pugnat, et al. Czech Journal of Physics, Vol.55 (2005), A389;Czech Journal of Physics, Vol.56 (2006), C193;
* * 1st results in Phys. Rev. D 78, 092003 (2008)
Axion Search
The OSQAR Experiments @ CERN For Low Energy Laser-based Particle/Astroparticle Physics
For the longer term: Toward the “axionic” laser
With 4 + 4 LHC Dipoles, i.e. Experiment of ~150 m long,…
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) Optical Search for QEDvacuum magnetic birefringenceAxion and photon Regeneration
New proposal
• Axion detection in the gradient of magnetic field
– For a massless axion → symmetry axion-photon (E. Guendelman 2008,…)
– Measurement of the light deflection in the high gradient of the magnetic field
Stern-Gerlach like experiment
– use of LHC quadrupole magnets
– Similar experiment for solar keV axions →
novel axion helioscope (,,new CAST’’)
The OSQAR Experiments @ CERN For Low Energy Laser-based Particle/Astroparticle Physics
Summary
Optical Search for QEDvacuum magnetic birefringenceAxion and photon Regeneration
• Effects predicted in early QED 70 years ago are for the first time within experimental reach
• A New Way (based on laser beams) of doing Particle Physics particles required by the Standard Model (axions) are searched by low energy experiments (complementarity to High Energy experiments)
• Spin-offs in the domain of metrology of electric & magnetic fields breaking world records in measurements of the rotation of polarization, ellipticity, large optical cavities etc.