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.