PRINCIPLE OF THE EXPERIMENT PRESENT RESULTS see Ref.(5)

E1PV: : PV E1 6S-7S amplitude

interferes withEz : Stark induced E1 amplitude

POLARIMETRIC METHOD OF MEASUREMENT ... and CALIBRATION

Input probe polarisation parallel

to ex, rotates during propagation by

an angle k PV (k : atomic factor)

Polarimeter imbalance left-right asymmetry

ALR(PV) (SX-SY)/(SX+SY) = 2 k PV

Calibration: rotating ex by cal probe rotation k cal ALR(cal) = 2 k cal

PV = [ALR(PV) / ALR(cal)] . cal

IMPLEMENTATION of the EXPERIMENT

EXCITATION AND DETECTION

4 Polarization configurations : 0°, 45°, 90°, 135°

Selection criteria of the PV rotational invariant

1 PV data

0,4s

0,8s

6s

2 mn

12s

PVexp

(µrad)

2002 20042003

1 point:400 PV data 1 point:

200 PV data

Excited vapour gain axes are // (and ), not to exc but to

exc+ PV exc^z : rotated from exc by an angle 10-6 rad,

odd in Ez

output probe polarn prout

= prin + k PVpr

in^z

atomic factor (Cs density, HFS,..)

zpvpv EE /1

OUR GOAL: measurement of E1PV with 1% precision

as a cross check of the Boulder 1999 result

A new independent measur’ of QW the weak charge of Cs nucleus as a precise test of the electroweak theories (Standard Model and

extensions, e.g. extra dimensions, additional gauge bosons..)

8 m

onth

s

7 w

eeks

cells

2002

EVOLUTION OF THE RESULTS (7 different cells)

August 2004

probe beam

excitation beam

REFERENCES

(1) "A New Manifestation of Atomic Parity Violation in Cesium: a Chiral Optical Gain induced by linearly polarized 6S-7S Excitation" , J. Guéna & al., Phys. Rev. Lett.  90, 143001 (2003).

(2) "Cylindrical symmetry discrimination of magnetoelectric optical systematic effects in a pump-probe atomic parity violation experiment’’ , M-A. Bouchiat & al., Eur. Phys. J. D28, 331 (2004).

(3) "Prospects for forbidden-transition spectroscopy and parity violation measurements using a beam of cold stable or radioactive atoms’’, S. Sanguinetti & al.,  Eur. Phys. J. D25, 3 (2003).

(4) "Proposal for high-precision Atomic Parity Violation measurements using amplification of the asymmetry by stimulated emission in a transverse E and B fields pump-probe experiment“, J. Guéna & al., JOSA B 22, 21 (2005).

(5) “Measurement of the parity violating 6S-7S transition amplitude in cesium within 2x10-13 atomic unit accuracy by stimulated emission”, J. Guéna, M. Lintz, and M- A. Bouchiat, Phys. Rev. A.71, 042108 (2005). ArXiv:physics/0412017.

(6) “Demonstration of an optical polarization magnifier with low birefringence”, M. Lintz & al., Rev Sci. Instr. 76, 4, 043102 (2005), arXiv:physics/0410044 .

(7) “An alkali vapor cell with metal coated windows for efficient application of an electric field”, D. Sarkisyan & al., Rev. Sci. Instr., 76, 053108. ArXiv:physics/0504020

(8) Review Article: “ Atomic Parity Violation: Principles, Recent Results, Present Motivations”, J. Guéna, M. Lintz, and M-A. Bouchiat,  Mod. Phys. Lett. A 20,6, 375 (2005). ArXiv:physics/0503143

THE CESIUM PARITY VIOLATION EXPERIMENT IN PARIS:

Determination of E1PV within 2x10-13 eao

J. Guéna, M. Lintz and M.-A. Bouchiat,

Département de Physique de l'ENS, 24 rue Lhomond, 75 231 Paris cedex 05, FRANCE

Particle physics...

...without accelerator!

HOW TO AMPLIFY THE PV EFFECTS?

cell input

S/N now adequate to reach 1% precision by

lengthening the acquisition time,

using last improved cesium cell (conductive windows, ref.7)

Updated average result : PV = 0.950 0.025 µrad

together with a 1% accurate Ez field in-situ determination from atomic signals

agrees with PV = 0.962 0.005 µrad, at 1.62 kV/cm

expected from Boulder result for E1PV//

We extract a new determination of E1PV

E1PV = (- 80.8 2.1) x 10 -13 eao

for the 6S ,F=3 – 7S, F=4 hyperfine transition

PASSIVE AMPLIFICATION

How to make a polarisation magnifier ?

6 brewster plates... with no two surfaces parallel ! (interference + linear dichroism birefringence)

Polarisation Magnifier at cell output :

Passive Amplification of the Polarisation Tilt

x 3

y

x

ty = 1/3tx = 1

But… 9 x less photons detected : photon shot noise also increased X 3 !

To gain in S/N we increase the probe intensity

dichroic component with axes x (transmission 1)

and y (transmission Ty << 1)

6 wedged silica plates

see Ref. (6)

Excited vapour anisotropic amplifier (: gain anisotropy)

exponential growth of both

probe intensity and left-right asymmetry vs. optical density

ALR 2 PV x [exp(A) -1]

= 2 ( E1PV/Ez) x [exp(A) -1]

where A = Ln( Iout/ Iin) : optical density, Ez2

Increase Ez at will? ... Not in practice :

high endcap potentials discharges at Ez > 2 kV/cm

...by the atomic medium itself!

Exploiting further ALR amplification: a new PV proposal in transverse E and B fieldsAdvantages in transverse field configuration:• Larger excitation rate (involves scalar polarisability =10x),• Longer interaction length possible without discharges

New cell design

to restore cylindrical symmetry by

rotating E and B fields by 45° steps

New observable = PV excited-state orientationprobe circular dichroism, detected using circular analyser

Predicted quantum-noise limit is reduced by a factor of 10,

or even more in the triggered superradiant regime !

possible design for a 0.1% statistical precision

ACTIVE AMPLIFICATION

-V1 V1

V1-V1

-V2

V2

0

0

Noise reduction

and increased rep. rate 160Hz

Dichroic mirror

Since first 9% result (cell # 1, Ref. 1), S/N improved by 3.5

acquisition time for S/N = 1 reduced by 12

probe polarimeter

see Ref.(4)