The YbF T-violaton experiment Ben Sauer

YbF experiment (2011) d e < 1 x e.cm (90% c.l.) We (and others!) are aiming here! What is interesting for the electron edm? Multi Higgs Left - Right MSSM  ~ 1 MSSM  ~  Predicted values for the electron edm d e (e.cm) Standard Model

© Imperial College LondonPage 3 T violation in a system with spin? E electric field de de  Interaction energy -  d e E  Analogous to magnetic dipole interaction -g e  B.  but violates P&T system containing electron Factor  includes both relativistic interaction  Z 3, and polarization

The basic idea: E electric field  E  B magnetic field

© Imperial College LondonPage 5 Key advantage of YbF: huge effective field  E Parpia Quiney Kozlov Titov 15 GV/cm Effective Field |  E| (GV/cm) Applied Electric Field (kV/cm)

YbF, Tl Cs, HfF +, WC ThO* PbO* atom/molecule level CP from particles to atoms (main connections) nuclear level NNNN Schiff moment Hg TlF Higgs SUSY Left/Right T-weak Strong CP field theory CP model  GG ~ neutron nucleon level electron/quark level d e, C s dqdcqdqdcq muon?

© Jony HudsonPage 7 A rough guide to YbF F = 1 F = 0 552nm 170MHz A 2  ½ (v=0, N=0) X 2  + (v=0, N=0) m F = -1m F = 0 m F = +1

© Jony HudsonPage 8 YbF hyperfine levels in an E field F = 1 F = 0 m F = 0 Large tensor Stark shift m F = -1 m F = +1

|0  |x  |0  |0   |0  |x  |x  |y 

© Jony HudsonPage 10 Spin interferometer Degenerate levels in YbF are split by Zeeman effect: T-violation:

© Jony HudsonPage 11 Spin magnetometer F = 1 F = 0 F=0 population

Timing Time = Position Vary pulse timings to probe different parts of machine Slice time-of-flight signal to probe local gradients Time after valve fires (  s) Fluorescence signal

Page 13 Measuring the EDM Applied magnetic field Detector count rate +E B0B0 -E -B 0  = 4 d e  ET/   = - 4 d e  ET / 

Page 14 Measuring the EDM For each shot of source, set direction of E and B fields, measure transmitted fluorescence. +E -B +B -E Time

Modulate everything ±E ±B ±B±B ±rf2f ±rf1f ±rf2a ±rf1a ±laser f ±rf  spin interferometer Signal 9 switches: 512 possible correlations  The EDM is the signal correlated with the sign of E.B (N.B. Blind in the analysis)  We study all the other 511 correlations in detail J. J. Hudson, M. R. Tarbutt, B. E. Sauer, E. A. Hinds, Stochastic multi-channel lock-in detection, arXiv: YbF eEDM software is open source:

True T-violating signal is An obvious correction What should happen What usually happens Molecular energy levels depend on E and B fields

Systematics: time of flight gradients Time (10  s bins) Correlation with rf frequency step for first rf pulse Time (10  s bins) Normalized correlation shows electric field gradient at first pulse

Magnetic noise  d in noisy periods is 3% higher than in quiet periods: shielding works!

Published results 68% statistical systematic - limited by statistical noise d e < 1 × e.cm with 90% confidence Previous result - Tl atoms d e < 1.6 × e.cm with 90% confidence d e = (-2.4  5.7  1.5) × e.cm 2011 result – YbF – Hudson et al. (Nature 2011) experiment: Regan et al. (PRL 2002) theory: Porsev et al. (PRL 2012)

Upgrades since rd layer of magnetic shield (less noise) Longer inner magnetic shield (reduce end effects) Separate rf, high-voltage plates (reduce end effects, higher voltage, less leakage) 1kW/1  s rf pulses (reduce gradient effects from both movement and linewidth) In total, a factor of 3 in sensitivity Longer interaction region

Future of YbF experiment Sensitivity is 1.6  e.cm/day We are aiming for a limit <3  e.cm with the current apparatus. Rebuilding machine suppressed systematics from 2011 measurement. We’ve found lots of new effects, some of which we are still investigating.

Sensitivity vs. signal size Signal size {  B} Spring 2013 edm sensitivity ( e.cm/block) Number of blocks (hundreds)

The future of YbF? Uncertainty: coherence time number of molecules contrast More YbF and slower YbF!

Future of YbF experiment Sensitivity isn’t everything! But more signal always helps. We can gain an order of magnitude with the current apparatus by adding an extra pump laser (N=2) and by detecting on a cycling transition (a P(1) line with all the sidebands). Slower source: YbF at 200m/s, not 600m/s. 4K cold plate

Future of YbF experiment The two improvements should improve the sensitivity by a factor of 15 and a factor of 3. Conclude: modified version of existing apparatus should be able to measure down to 1  e.cm. Better still?

Proposed YbF fountain 4K Fantastically inefficient: from cell to detector. But T = 300ms, so 60h of data gives  d = 3x e.cm! Design for a fountain of YbF molecules to measure the electron's electric dipole moment M R Tarbutt, B E Sauer, J J Hudson and E A Hinds New J. Phys. 15 (2013)

Laser cooling molecules (CaF, SrF) Anne Cournol Mike Tarbutt B.E.S Aki Matsushima ValentinaJony Hudson Ed Hinds Zhelyazkova

The YbF EDM team Joe Smallman B.E.S. Jack Devlin Jony Hudson Mike TarbuttEd Hinds

References Theory Tl: Z.W. Liu and H. P. Kelly, Phys. Rev. A 45, R4210 (1992); V. A. Dzuba and V.V. Flambaum, Phys. Rev. A 80, (2009); H. S. Nataraj, B. K. Sahoo, B. P. Das, and D. Mukherjee, PRL 106, (2011); S. G. Porsev, M. S. Safronova, and M. G. Kozlov, PRL 108, (2012). YbF: M. G. Kozlov and V. F. Ezhov, Phys. Rev. A 49, 4502 (1994). A. V. Titov, N. S. Mosyagin, and V. F. Ezhov, PRL 77, 5346 (1996). M. G. Kozlov, J. Phys. B: At. Mol. Opt. Phys. 30 (1997) L607–L612. H M Quiney, H Skaane and I P Grant, J. Phys. B: At. Mol. Opt. Phys. 31 (1998) L85. Farid A Parpia, J. Phys. B: At. Mol. Opt. Phys. 31 (1998) N S Mosyagin, M G Kozlov and A V Titov, J. Phys B: At. Mol. Opt. Phys. 31 (1998) L763. ThO: Edmund R. Meyer and John L. Bohn, Phys. Rev. A 78, R (2008). Experiment: Tl: B. C. Regan, Eugene D. Commins, Christian J. Schmidt, and David DeMille, Phys. Rev. Lett. 88, (2002). PbO: S. Eckel, P. Hamilton, E. Kirilov, H.W. Smith, and D. DeMille, arxiv: (2013). YbF: J. J. Hudson, B. E. Sauer, M. R. Tarbutt, and E. A. Hinds, Phys. Rev. Lett. 89, (2002). J. J. Hudson, D. M. Kara, I. J. Smallman, B. E. Sauer, M. R. Tarbutt, E. A. Hinds, Nature 473, 493 (2011). D. M. Kara, I. J. Smallman, J. J. Hudson, B. E. Sauer, M. R. Tarbutt and E. A. Hinds, New J. Phys. 14, (2012). M.R. Tarbutt, B.E. Sauer, J.J. Hudson, E.A. Hinds, New J. Phys (2013). B. E. Sauer · J. A. Devlin · J. J. Hudson · D. M. Kara ·I. J. Smallman · M. R. Tarbutt · E. A. Hinds, Hyperfine Interact. 214, 119 (2013).

Comparing some atomic and molecular systems YbF, 2011: |E eff |= 14.5 GV/cm (  = 0.56) |d e |<1.0 x e.cm (90% c.l.) Tl, 2002: |E eff |= 72MV/cm (E eff = -582 E applied ) |d e |<1.6 x e.cm (90% c.l.) PbO*, 2013: |E eff |= 25 GV/cm |d e |<1.7 x e.cm (90% c.l.) ThO*: |E eff | = 104 GV/cm