o ptical s earch for q ed vacuum magnetic birefringence, a xion & photon r egeneration

Optical Search for QED vacuum magnetic birefringence,

Axion & photon Regeneration

Optical Search for QEDvacuum magnetic birefringenceAxion and photon Regeneration

Laser-based Particle/Astroparticle Physics Experiments at CERN To Test QED & probe the Low Energy Frontier…

2010 Status Report , from P. Pugnat on the behalf of the OSQAR Collaboration

99th Meeting of the SPSC (CERN), 16 November 2010

► 26 Members from 11 Institutes (CERN, Cz, Fr & Po)

The OSQAR Experiments @ CERN For Low Energy Laser-based Particle/Astroparticle Physics 2

CERN, Geneva, Switzerland G. Deferne, P. Pugnat (now at LNCMI-CNRS), M. Schott, A. Siemko

Charles University, Faculty of Mathematics & Physics, Prague, Czech Republic M. Finger Jr., M. Finger, M. Slunecka

Czech Technical University, Faculty of Mechanical Engineering, Prague, Czech Republic J. Hošek, M. Kràl, K. Macuchova, M. Virius, J. Zicha

ISI, ASCR, Brno, Czech Republic A. Srnka

IMEP/LAHC - INPG, 38016 Grenoble Cédex-1, France L. Duvillaret, G. Vitrant, J.M. Duchamp

IN, CNRS – UJF & INPG, BP 166, 38042 Grenoble Cédex-9, France B. Barbara, R. Ballou

LASIM , UCB Lyon1 & CNRS, 69622 Villeurbannes, FranceM. Durand (now at NIST, Gaithersburg), J. Morville

LSP, UJF & CNRS, 38402 Saint-Martin d'Hères, France R. Jost, S. Kassi, D. Romanini

TUL, Czech Republic M. Šulc

Warsaw University, Physics Department, Poland A. Hryczuk, K. A. Meissner


http://www.vslib.cz/en/

http://www.vslib.cz/en/

http://www-lsp.ujf-grenoble.fr/

http://www.uw.edu.pl/

http://www.uw.edu.pl/

http://neel.cnrs.fr/





Outline

• Introduction

• Scientific Motivations

• Reminder of the OSQAR Experiments– VMB Measurement– Photon Regeneration (PR) Experiment

• Progress achieved in 2010 & Expected for 2011/12

• Short & Long Time Perspectives

• Summary, Perspectives & Requirements for 2011


Scientific Motivations

► Complementary to the LHC


The OSQAR Experiments @ CERN For Low Energy Laser-based Particle/Astroparticle Physics

Physics at the Sub-eV scale to search WISPs (Weakly Interacting Sub-eV Particles)

Physics at the TeV scale to search WIMPs (Weakly Interacting Massive Particles)

Many extensions of the Standard Model, like those based on supergravity or superstrings, predict not only WIMPS but also WISPs…

4

x

x

Delbrück scattering

Scientific Motivations in a Nutshell


• To measure for the 1st time the Vacuum Magnetic Birefringence predicted by the QED (Heisenberg & Euler, Weisskopf, 1936) i.e. the vacuum magnetic “anomaly” of the refraction index “ n-1” ~ 10-22 in 9.5 T

• To explore the Physics at the Low Energy Frontier (sub-eV)– Axion & Axion Like Particles i.e. solution to the strong CP problem

(Weinberg, Wilczek, 1978) & Non-SUSY Dark Matter candidates (Abbott & Sikivie; Preskill, Wise & Wilczek, 1983)

– Paraphotons (Georgi, Glashow & Ginsparg, 1983), Milli-charged Fermions– Chameleons (Khoury & Weltman, 2003)– The unknown …

• A New Way of doing Particle Physics based on Laser beam(s)

• Spin-offs in the domain of the metrology of electric & magnetic fields


Principles of the Experiments


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

g9.5 T

x

g

~ 53 m


LN2 cooled CCD

Use of 2 LHC cryo-dipoles (double apertures) for Phase-1 & 2

6


• Axions Change of the linear polarisation of a laser beam after propagation in the vacuum with B transverse :– Elliptical– “Pseudo”-rotation

• Background for the ellipticity coming from the QED VMB Physics is guaranteed

• Very small effects ~10-14 rad / T2 km3

optical cavity to increase the path in B

P. Pugnat, L. Duvillaret, M. Finger, M. Kral , A. Siemko, J. Zicha Czechoslovak Journal of Physics, Vol.55 (2005), A389;Optical scheme with inputs from D. Romanini.

L. Maiani, R. Petronzio, and E. Zavattini, Phys. Lett. 175B (1986) 359Field Modulation at 1-10 mHz& dedicated filtering techniques

LASER

PD

ampli

Laser-cavity frequency locking (Pound-Drever)

Wollaston prism

EOM EO Modulator

High finesse cavity

LHC dipole magnet

PDUH vacuum

Opt.Isol.

ModeMatching

optics

PD

LASER

PD

ampliampli

Laser-cavity frequency locking (Pound-Drever)

Wollaston prism

EOM EO Modulator

High finesse cavity

LHC dipole magnet

PDUH vacuum

Opt.Isol.

ModeMatching

optics

PD

Phase 1

)4cos()4sin(1~

opt ttP

VMB & Linear Dichroism measurements to test QED & Search Axion/ALP: Principle & Proposed Optical Scheme

VMB ~10-14 rad / T2 km

VMB measurement – The key problem to solve : How to get rid of the birefringence & dichroism of the optical cavity ?

• A new approach was proposed by a team from OSQAR & presented in 2009 (SPSC-SR-053-2009; http://indico.cern.ch/conferenceDisplay.py?confId=73796)


http://indico.cern.ch/conferenceDisplay.py?confId=73796


xqin

qout

y

fin

fout

B

Maintain the high finesse of the cavity during the synchronous rotation of the mirrors around their optical axis

VMB & Linear Dichroism measurements- (R)evolution of the optical scheme

Use residual mirrors birefringence as an optical bias for homodyne detection

From SPSC-SR-053 Expected sensitivity

10 hours of time integration 10-13 rad

Cavity in transmission instead of reflection 2 10∙ -14 rad

Optimized mirrors in the long cavity 2 10∙ -15 rad

Optimized electronics 10-15 rad

VMB ~10-13 rad

An update for the OSQAR-VMB is in preparation

Photon Regeneration runs in 2010Optical Search for QEDvacuum magnetic birefringenceAxion and photon Regeneration

“An invisible light shining through a wall” K. van Bibber et al. PRL 59 (1987) 759

The Boss Borrowed from Aaron S. Chou, SLAC HEP seminar, Jan. 14, 2008


Photon Regeneration ► 1st operation in 2010 with 2 aligned LHC dipoles

A

B

C

A

B

C

D

E

F

D

E

F

B1

E153 m


11

Safety Issues – Operation of a Class IV laser

• Additional constraints coming from the open access of the SM18 hall to visitors

• Safety audit of

March 8th

- Strict Procedure for operation (EDMS doc1063882 v.3)

- Improvements of the beam shielding

- Modification of the water circuit for the laser cooling


Overview of the experimental runs in 2010


Period OSQAR configuration Data acquisition runs22 - 25 February Photon Regeneration

► 2 LHC dipoles temporary used/available

► 18 W Ar+ laser with linear polarization // B

Cumulative time integration of ► 0.83 h for scalar search ► 0.67 h for paraphoton search

Breakdown of the Laser

15 March - 9 June Shutdown of the cryogenics

19 June - 7 July ► 1 LHC dipole temporary used/available

► 14 W Ar+ laser (new one provided by ESPCI-Paris)

Background study & long term stability runs

19 - 27 August Photon Regeneration► 2 LHC dipoles temporary

used/available► 14 W Ar+ laser (new one provided

by ESPCI-Paris) with linear polarization B

Cumulative time integration of

► 85 h for pseudo-scalar search► 18.5 h for scalar search► 72 h for background


Exemple of raw & filtered data

Filtering of raw data to supress cosmic signals from each frame before accumulation



Statistical analysis

to built exclusion limits

Preliminary

Preliminary

Preliminary Results for 2010 Runs

• Detailed analysis is undergoing

• CCD background stability makes difficult the combined analysis between all data sets

• 1st analysis (conservative) of best data sets– 12.7h/6.5W for

pseudoscalar– 7.37h/6.7W for

scalar


Preliminary

► The expected sensitivity in 2009 (SPSC-M-770) has been reached


Sensitivity of the Photon Regeneration Experiment

Exclusion limit for gAgg

B (T) B-1

Magnetic Length (m) L-1

Optical power (W) P-1/4

Detection threshold (g/s) dN g /dt 1/4

Time integration Dt-1/8


Source of scalar or pseudo-scalar particles

Photon regeneration region

Ar+ Laser with chopper

Optical barrier Polarizer

B = 9 T

Detection: Synchronous photon counting with chopped laser beam

N2 cooled CCD Detector

A

x x

P. Sikivie, PRL 51 (1983) 11415

K. van Bibber et al. PRL 59 (1987) 759

0for of Maximum

in vacuum 2

and

2sin

2)(

4

1with

2

2

2

2

qLP

mk-kq

qL

qLBLgP

PP

dt

dN

A

AAγ

A

A

A

A

Expected exclusion limits for 2011/12

• Assumptions- 24 h of time integration

- Optical power x 50

- New CCD allowing a background reduction by 50

► Target = toimprove the ALPs limit by x5


Expectation


How to increase the optical power ?► By extending the laser cavity



• A laser cavity extended up to 5 m inside the magnet aperture was already built ►With an intra-cavity CW power larger than few 100 W

• Need to be repeated with the new laser & a mirror with a larger radius to extend the cavity up to 20 m…


Experiments- Expected results - Short & “Long” Term Perspectives

PVLAS, PRL 96 (2006)

CAST-2003, PRL 94(2005)

ALPs 2010

Expectation for 2011/12 OSQAR-PR

From C. Hagmann, K. van Bibber, L.J. Rosenberg, Physics Lett. B, vol.592, 2004


• 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) and ALPs (2011-2012)

- Phase-2 : 2 dipoles, CW laser beam & High Finesse FP cavity (2013-2014)

- Phase-3 : more than 2 dipoles to be competitive with CAST (long term)

• “n-1 Experiment” i.e. VMB & Linear Dichroism

- Phase-1&2 : Measurements of QED prediction in O(a2) & O(a3) respectively within 1 dipole (2013 & 2014 at the earliest…)

*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

19


For the longer term: Toward the “axionic” laser

With 4 + 4 LHC Dipoles, i.e. Experiment of ~150 m long,…

Ph

ys. R

ev. L

ett.

98, 1

7200

2 (

2007

) Optical Search for QEDvacuum magnetic birefringenceAxion and photon Regeneration

20

Summary, Perspectives & Requirements

• The potential discovery of the OSQAR-PR was significantly improved in 2010 with the simultaneous use of 2 LHC dipoles

• The sensitivity obtained for pseudoscalar & scalar search has reached the foreseen target and is only surpassed today by the new results of the ALPs experiment

• OSQAR-PR limitations due to the :

- Less than expected availability of the LHe cooling capacity at SM18

- Reduced optical power of the laser

- Poor performances of the CCD detector

• Perspectives for 2011 & 2012

- To break the OSQAR-PR limitations

► Increase the time integration

► Extend the laser cavity up to 20 m

► New CCD

- This, to improve the exclusion limits for pseudoscalar & scalar search by about one order of magnitude

- To develop a first prototype of a rotating Fabry perot cavity for the VMB measurement

• Requests for 2011

- 2 LHC dipoles at cold condition for at least 1 period of 2 weeks and 4 periods of 1 week each



Acknowledgements

The OSQAR collaboration would like to thank

- Gilles Tessier from ESPCI-Paris (Ecole Supérieure de Physique & de Chimie Industrielles de la ville de Paris) to have provided the new 14 W Ar+ laser, - The CERN teams of the SM18-test hall (MSC-TF, CRG-OD, RF-KS) for their valuable technical contributions, inputs and advices, as well as- The management of CERN-TE department for continuous support.


o ptical s earch for q ed vacuum magnetic birefringence, a xion & photon r egeneration

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