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Electric dipole moment searches

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Presentation on theme: "Electric dipole moment searches"— Presentation transcript:

1 Electric dipole moment searches
Peter Fierlinger

2 Outline Motivation Different systems to search for electric dipole moments (EDMs) Examples P. Fierlinger – MeNu2013

3 Electric dipole moment
Magnetic moment A non-zero particle EDM violates P … and T (time reversal symmetry) … assuming CPT conservation, also CP - Purcell and Ramsey, PR78(1950)807 EDM + P. Fierlinger – MeNu2013

4 History EDM limits [] SM neutron SM electron MSSM ~/
L-R symmetric Multi- Higgs ~1 e- n p Ramsey & Purcell (1950) n n+Hg Xe n e-(Tl) EDM limits [] n Hg `01 Hg `09 Atoms e-

5 Neutron EDM and the SM CP violation from CKM Strong Interaction
CP-odd term in Lagrangian: Khriplovich Zhitnitsky (1986), McKellar et al., (1987) E.g. Pospelov, Ritz, Ann. Phys. 318(2005)119 M. Pospelov, et al., Sov. J. Nucl. Phys. 53, 638 (1991) Neutron EDM dn  ecm (de < ecm) dn much more difficult to calculate, but still small Strong CP problem T. Mannel, N. Uraltsev, Phys.Rev. D85 (2012) P. Fierlinger – MeNu2013

6 Baryon asymmetry Remarks: Observed: nB / nγ Expected: ~ 6 x 10-10
(BBN, CMB) Expected: nB / nγ ~ MUCH smaller e.g. astro-ph/ ‚Ingredients‘ to model baryogenesis: Sakharov criteria JETP Lett. 5 (1967) 24 Remarks: e.g. Cirigliano, Profumo, Ramsey-Musolf JHEP 0607:002 (2006) Beyond-SM physics usually requires large EDMs EDMs and Baryogenesis via Leptogenesis? Also other options w/o new CP violation possible (Kostelecky, CPT) SUSY: small CPV phases, heavy masses, cancellations? What do we learn from an EDM? Different measurements are needed! P. Fierlinger – MeNu2013

7 polar / charged molecules
Physics behind EDMs dq dq ~ Cqe Cqq de d d gNN CS,P, T Neutron, proton Leptons See e.g. Pospelov, Ritz, Ann. Phys. 318(2005)119 Ions Schiff-Moment  Z² Schiff-Moment  Z³ Diamagnetic atoms Paramagnetic atoms, polar / charged molecules P. Fierlinger – MeNu2013

8 Atom EDM Schiff moment: Eext
Non-perfect cancellation of Eext in atomic shell Paramagnetic atoms ~ electron EDM Relativistic effects Sandars, 1968 L. Schiff, Phys. Rev. 132, 2194 (1963) Diamagnetic atoms ~ nuclear EDM Finite size of nucleus violates Schiff‘s theorem Eext Schiff 1963; Sandars, 1968; Feinberg 1977; Large enhancements also with deformed nuclei (Ra, Rn, also Fr, Ac, Pa) P. Fierlinger – MeNu2013

9 Atomic effects Contributions to atomic EDMs:
13 (model-dependent) parameters TeV-scale CP odd physics, nucleon level, nucleus-level Only 8 types of experiments Illustration: T. Chupp et al., to be published *) See also J. Engel, M. J. Ramsey-Musolf, U. van Kolck, Prog. Part. Nucl. Phys. 71, 21 (2013) gπ1 gπ0 P. Fierlinger – MeNu2013

10 Measuring the neutron EDM
(RAL/SUSSEX/ILL experiment) Ultra-cold neutrons (UCN) trapped at 300 K in vacuum Ekin < 250 neV  > 50 nm T ~mK Storage ~ 102 s B0 ~ 0.5 m P. Fierlinger – MeNu2013

11 Ramsey‘s method EDM changes frequency:
Particle beam or trapped particles Polarization E 1-L („detuning“) EDM changes frequency: P. Fierlinger – MeNu2013

12 Clock-comparison experiment
- Neutrons and 199Hg stored in the same chamber - Gravity changes center of mass! B =1 T ( + small vertical gradient) Physical Review Letters  97 (2006) Illustration (2008 data) Analysis using the gradient: B0 down B0 up dn < 2.9 x e cm Applied Gradient Requirement: 199Hg-EDM must be small: (btw., this also limits other parameters, e.g CS, CT...): dHg < 3.1 x e cm Frequency ratio Hg-EDM: W. C. Griffith et al., PRL 102, (2012) P. Fierlinger – MeNu2013

13 Neutron and proton experiments
nEDM Cryo EDM ILL Crystal EDM FRM-II EDM JPARC NIST Crystal PNPI/ILL PSI EDM SNS EDM TRIUMF/RNPC pEDM Jülich BNL Method 4He Solid sD2 Cold beam Turbine B and E field ring Electrostatic ring Goal (x10-28 ecm) ~ 50; 2. < 5 < 100 < 5 < 10 1. ~ 100; 2. < 10 1. ~ 50; 2. < 5 1. R&D; ; 10-29 Comments Larger revisions to come Diffraction in crystal: large E Adjustable UCN velocity Special UCN handling R&D E = 0 reference cell Phase 1 takes data Sophisticated technology Phase II at TRIUMF Stepwise improvements Completely novel technology P. Fierlinger – MeNu2013

14 ‚Current generation‘ improvements
PSI (taken from B. Lauss, K. Kirch), for actual numbers see PSI EDM talk PNPI/ILL (taken from A. Serebrov, 2013): UCN density measured in a 25l volume extrapolated to t=0 at PSI area West-1 2010 ~0.15 UCN/cm3 2011 ~18 UCN/cm3 2012 ~23 UCN/cm3 correct for detector foil transmission status (4/2013) >33 UCN/cm3 in storage experiment (-> this is an extrapolation) < 2 UCN/cm3 in EDM experiment UCN density 3-4 ucn/cm3 (MAM position) Electric field 10 kV/cm T(cycle) = 65 s electric field 20 kV/cm δDedm ~ 5∙ e∙cm/day ~ 2014: EDM position at PF2 1∙ e∙cm/100 days δDedm ~ 2.5∙ e∙cm/day 14 P. Fierlinger – MeNu2013

15 SQUID measurements of Sussex EDM electrodes @ PTB Berlin
‚Next generation‘ Most critical for next generation experiments: ‚geometric phases‘ Example: Dipole fields in EDM chambers 20 pT in 3 cm ~ 5 x error budget! SQUID measurements of Sussex EDM PTB Berlin Pendlebury et al., Phys. Rev. A 70, (2004) Magnetic field requirements for ecm – level accuracy: ~ fT field drift error, ~ < 0.3 nT/m avg. gradients df ~ ecm (199Hg geom. phase) dn ~ ecm (UCN geom. phase) ~ 0.3 m demagnetized: 20 pT pp 200 pT pp Statistics: 103 UCN/cm3 ~ 1 year Further: P. G. Harris et al., Phys. Rev. A 73, (2006), also: G. Pignol, arXiv: (2012). P. Fierlinger – MeNu2013

16 New sources of UCN Superthermal solid D2 or superfluid 4He-II
SD2: Molceular excitations used to cool neutrons to zero energy - similar: ILL, LANL, Mainz, NCSU, PNPI, PSI, TUM … 4He: ILL, KEK, SNS, TRIUMF, … Goal of most sources: 10³ UCN /cm³ in experiment P. Fierlinger – MeNu2013

17 Magnetic fields The smallest extended size field and gradient on earth
< 100 pT/m gradient in 0.5 m3 At FRM-II EDM setup: fields designed and measured -this technology is ready and available! z = 0.5 m z = 0 m (center) z = m x [m] [nT] SQUID offset in z not corrected y [-0.5 m – 0.5 m] P. Fierlinger – MeNu2013

18 Next generation neutron EDMs
E.g. at FRM-II (reactor): ‚Conventional‘, double chamber UCN velocity tuning Cs, 3He, 199Hg, 129Xe (co)magnetometers Ready for UCN in 1 year E.g. at SNS (spallation): Cryogenic, double chamber Neutron detection via spin dependent 3He absorption and scintillation 3He co-magnetometry In the future... again nEDM with a cold beam? Pulse structure and strong peak flux: Cold-beam-EDM at long-pulse-neutron source (ESS) could be competitive? (Piegsa, PRC, soon...) Re-accelerated polarized UCN with pulse-structure? (PF, in prep.) P. Fierlinger – MeNu2013

19 Next generation nucleon EDMs
Proton, deuteron, ... EDM Charged particle EDM searches require the development of a new class of high-precision storage rings Projected sensitivity ~ ecm: … tests  to < 10-13! Currently 2 approaches: JEDI collab.: starting with COSY ring, development in stages E, B fields BNL: completely electrostatic, new design all-electric ring Requirements: Electric field gradients 17 MV/m (possible) Spin coherence times > 1000 s (200s demonstrated at Jülich) Continuous polarimetry < 1 ppm error (demonstrated at Jülich) Spin tracking simulations of 109 particles over 1000 s P. Fierlinger – MeNu2013

20 Proton EDM in ‚magic‘ ring
- Frozen horizontal spin precession: p || s - EDM turns s out of plane P, S aligned V. Bargmann, L. Michel and V. L. Telegdi, Phys. Rev. Lett. 2 (1959) 435. Magic ring: - Purely electric ring only for G > 0 - E and B ring for other isotopes erklären wo der spin hindeutet Electrostatic ring proposal at BNL Figures: H. Stroeher P. Fierlinger – MeNu2013

21 Octupole deformations: 225Ra
Enhancement factors: EDM (225Ra) / EDM (199Hg) ~ 103 Ra Oven: Zeeman Slower Optical dipole trap EDM probe Why trap 225Ra atoms: efficient use of the rare 225Ra atoms high electric field (> 100 kV/cm) long coherence times ~ 100 s negligible “v x E” effect Nuclear Spin = ½ t1/2 = 15 days Schiff moment of 225Ra, Dobaczewski & Engel, PRL (2005) Magneto-optical trap Goal ~ ecm Main issue: statistics (Project X?) MOT: Guest et al., PRL (2007) Dipole trap: Trimble et al. (2010) Figures: Z.-T. Lu P. Fierlinger – MeNu2013

22 Lepton EDM measurements
Best limits: Mainly paramagnetic systems and polar molecules Cs, Tl, YbF: de < ecm (E. Hinds et al.) Soon: ThO – currently taking data Molecules, molecular ions, solids: PbO, PbF, HBr, BaF, HgF, GGG, Gd2Ga5O12 etc. dGGG ~ < ecm d < (90%) ecm from g-2 d < (90%) ecm from Z Diamagnetic atoms also contribute to such limits! Shapiro, Usp. Fiz. Nauk., (1968) tau ... CP Tl, YbF limits together, courtesy T. Chupp (2013) P. Fierlinger – MeNu2013

23 The ACME experiment Status: taking data with 10-28 ecm /day
ThO molecules: 100 GV/cm internal electric field due to level structure, polarizable with very small lab-field Small magnetic moment, therefore less sensitive to B-field quality High Z: enhancement Well understood system Lasers to select states High statistics: strong cold beam Status: taking data with ecm /day Figures: J. Doyle P. Fierlinger – MeNu2013

24 Summary New EDM experiments are highly sensitive probes for new physics Several experiments must be performed to understand the underlying physics. (Then, also a measured limit may be a discovery...) Experimental techniques span from table top AMO - solid state - low temperature – accelerators - neutron physics Next generation precision within next 2 years: nEDM ~ few ecm atoms ~ < ecm (ThO, 199Hg, 129Xe) 6 years: nEDM ~ few ecm atoms - hard to predict ... Note: my nEDM time estimate stayed constant since 2009 P. Fierlinger – MeNu2013

25 New concepts? Re-acceleration of UCN
A possibility to produce extremely high brightness ‚cold‘ neutron beams: concept demonstrated (Rauch et al.) Next step: Perfect polarization (PF et al.) S. Mayer et al., NIM A 608 (2009) 434–439 Again: nEDM measured with a cold beam? Beam-EDM at long-pulse-neutron source could be competitive (Piegsa et al., to be published soon) Why not use a combination: perfectly polarized, re-accelerated high brightness beam with extremely well known time structure for in-beam EDM?

26 Supersymmetry More sources of CP violation Consequences small phases:
~ EDMs at 1 loop level MSSM example: MSSM for M = 1 TeV, tan =3 Hg EDM ~ exp. Limit! Boson coupling Pospelov, Ritz, Ann. Phys. 318(2005)119 Consequences small phases: problem for baryogenesis cancellations: requires tuning heavy masses Higgsino mass phase P. Fierlinger – MeNu2013

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