Electric dipole moment searches Peter Fierlinger Outline Motivation Different systems to search for electric dipole moments (EDMs) Examples P. Fierlinger – MeNu2013 Electric dipole moment Magnetic moment A non-zero particle EDM violates P EDM + Purcell and Ramsey, PR78(1950)807 … and T (time reversal symmetry) … assuming CPT conservation, also CP P. Fierlinger – MeNu2013 History L-R symmetric n MSSM ~1 p EDM limits [e.cm] n n+Hg Xe e-(Tl) en MultiHiggs n Hg `01 Hg `09 Atoms MSSM ~/ eSM neutron SM electron Neutron EDM and the SM Strong Interaction CP-odd term in Lagrangian: s ~ L GG 8 M. Pospelov, et al., Sov. J. Nucl. Phys. 53, 638 (1991) d n ( ) ~ Neutron EDM dn 10-32 ecm (de < 10-38 ecm) - dn much more difficult to calculate, but still small T. Mannel, N. Uraltsev, Phys.Rev. D85 (2012) 096002 P. Fierlinger – MeNu2013 e m* ~ 6.1017 e cm mn QCD 10 10 Strong CP problem E.g. Pospelov, Ritz, Ann. Phys. 318(2005)119 Khriplovich Zhitnitsky (1986), McKellar et al., (1987) CP violation from CKM Baryon asymmetry Observed: nB / nγ ~ 6 x 10-10 (BBN, CMB) e.g. astro-ph/0603451 JETP Lett. 5 (1967) 24 ‚Ingredients‘ to model baryogenesis: Sakharov criteria Remarks: - 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 e.g. Cirigliano, Profumo, Ramsey-Musolf JHEP 0607:002 (2006) Expected: nB / nγ ~ MUCH smaller dq d~q Neutron, proton Ions de d d Cqe Cqq gNN CS,P, T Schiff-Moment Z² Diamagnetic atoms Leptons Schiff-Moment Z³ Paramagnetic atoms, polar / charged molecules P. Fierlinger – MeNu2013 See e.g. Pospelov, Ritz, Ann. Phys. 318(2005)119 Physics behind EDMs Atom EDM Non-perfect cancellation of Eext in atomic shell Paramagnetic atoms ~ electron EDM Relativistic effects d a de Z 3 Sandars, 1968 Diamagnetic atoms ~ nuclear EDM Finite size of nucleus violates Schiff‘s theorem da dnucl Z 2 Eext Schiff 1963; Sandars, 1968; Feinberg 1977; ... - 2010 Large enhancements also with deformed nuclei (Ra, Rn, also Fr, Ac, Pa) P. Fierlinger – MeNu2013 L. Schiff, Phys. Rev. 132, 2194 (1963) Schiff moment: Atomic effects - 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 *) gπ1 See also J. Engel, M. J. Ramsey-Musolf, U. van Kolck, Prog. Part. Nucl. Phys. 71, 21 (2013) Contributions to atomic EDMs: gπ0 P. Fierlinger – MeNu2013 Measuring the neutron EDM Ultra-cold neutrons (UCN) trapped at 300 K in vacuum Ekin < 250 neV > 50 nm T ~mK Storage ~ 102 s ~ 0.5 m P. Fierlinger – MeNu2013 (RAL/SUSSEX/ILL experiment) B0 Ramsey‘s method Polarization Particle beam or trapped particles E 1-L („detuning“) d n EDM changes frequency: w L ~ mB + dE P. Fierlinger – MeNu2013 2 ET N Clock-comparison experiment - Neutrons and 199Hg stored in the same chamber B =1 T ( + small vertical gradient) Applied Gradient Illustration (2008 data) B0 up B0 down Analysis using the gradient: dn < 2.9 x 10-26 e cm Physical Review Letters 97 (2006) 131801. - Gravity changes center of mass! Requirement: 199Hg-EDM must be small: (btw., this also limits other parameters, e.g CS, CT...): Frequency ratio dHg < 3.1 x 10-29 e cm P. Fierlinger – MeNu2013 Hg-EDM: W. C. Griffith et al., PRL 102, 101601 (2012) Neutron and proton experiments nEDM Method Goal (x10-28 ecm) Comments Cryo EDM 4He 1. ~ 50; 2. < 5 Larger revisions to come ILL Crystal EDM Solid < 100 Diffraction in crystal: large E FRM-II EDM sD2 <5 Adjustable UCN velocity JPARC sD2 < 10 Special UCN handling NIST Crystal Cold beam < 10 R&D PNPI/ILL Turbine 1. ~ 100; 2. < 10 E = 0 reference cell PSI EDM sD2 1. ~ 50; 2. < 5 Phase 1 takes data SNS EDM 4He <5 Sophisticated technology TRIUMF/RNPC 4He < 10 Phase II at TRIUMF Jülich B and E field ring 1. R&D; 2. 10-24; 3. 10-29 Stepwise improvements BNL Electrostatic ring 10-29 Completely novel technology pEDM P. Fierlinger – MeNu2013 ‚Current generation‘ improvements PSI (taken from B. Lauss, K. Kirch), for actual numbers see PSI EDM talk 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 PNPI/ILL (taken from A. Serebrov, 2013): UCN density 3-4 ucn/cm3 (MAM position) Electric field 10 kV/cm T(cycle) = 65 s δDedm ~ 5∙10-25 e∙cm/day ...new electric field 20 kV/cm δDedm ~ 2.5∙10-25 e∙cm/day P. Fierlinger – MeNu2013 ~ 2014: EDM position at PF2 1∙10-26 e∙cm/100 days 14 ‚Next generation‘ Example: Dipole fields in EDM chambers SQUID measurements of Sussex EDM electrodes @ PTB Berlin Magnetic field requirements for 10-28 ecm – level accuracy: ~ fT field drift error, ~ < 0.3 nT/m avg. gradients df ~ 4.10-27 ecm (199Hg geom. phase) dn ~ 1-2.10-28 ecm (UCN geom. phase) Statistics: 103 UCN/cm3 ~ 1 year P. Fierlinger – MeNu2013 ~ 0.3 m Pendlebury et al., Phys. Rev. A 70, 032102 (2004) Most critical for next generation experiments: ‚geometric phases‘ 200 pT pp demagnetized: 20 pT pp 20 pT in 3 cm ~ 5 x error budget! Further: P. G. Harris et al., Phys. Rev. A 73, 014101 (2006), also: G. Pignol, arXiv:1201.0699 (2012). 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 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 = - 0.5 m x [m] [nT] SQUID offset in z not corrected y [-0.5 m – 0.5 m] P. Fierlinger – MeNu2013 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 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 ~ 10-29 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 Proton EDM in ‚magic‘ ring Thomas-BMT equation p || s (Bargmann, Michel, Telegdi) ds dt = Ω ×ds =s Ω × s Ω= dt e Ω = e [GB + G − 121 1 + v × B)] v × E + 1 η(E mc [GBmc+ G − γ 2γ− −11 v × E 2+ 2 η(E + v d= η d= η e S, 2mc µ = 2(G + 1) e S, 2m e e S, µ = 2(G + 1) S, d: electric dipole moment 2mc 2m G= g− 2 , 2 g G= × B)] −2 , 2 µ: magnetic moment, g:g− factor , G: anomalous magnetic Magic ring: moment d: electric dipole moment γ: Lorentz factor -µ:Purely >0 magneticelectric moment,ring g:g− only factor for , G: G anomalous magnetic -moment E and B ring for other isotopes V. Bargmann, L. Michel and V. L. Telegdi, Phys. Rev. Lett. 2 (1959) 435. γ: Lorentz factor 20 / 50 V. Bargmann, L. Michel and V. L. Telegdi, Phys. Rev. Lett. 2 (1959) 435. Electrostatic ring proposal at BNL 20 / 50 P. Fierlinger – MeNu2013 Figures: H. Stroeher V. Bargmann, L. Michel and V. L. Telegdi, Phys. Rev. Lett. 2 (1959) 435. - Frozen horizontal spin precession: Spin Motion is governed by Thomas-BMT Thomas-BMT equation equation (Bargmann, Michel, Telegdi) - EDM turns s out of plane Spin Motion is governed by Thomas-BMT equation Octupole deformations: 225Ra Ra Oven: Nuclear Spin = ½ t1/2 = 15 days Dipole trap: Trimble et al. (2010) MOT: Guest et al., PRL (2007) - Goal ~ 10-28 ecm - Main issue: statistics (Project X?) 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 Zeeman Slower Magneto-optical trap EDM probe Optical dipole trap P. Fierlinger – MeNu2013 Figures: Z.-T. Lu Schiff moment of 225Ra, Dobaczewski & Engel, PRL (2005) Enhancement factors: EDM (225Ra) / EDM (199Hg) ~ 103 Lepton EDM measurements Best limits: Shapiro, Usp. Fiz. Nauk., 95 145 (1968) Mainly paramagnetic systems and polar molecules - Cs, Tl, YbF: de < 1.05.10-27 ecm (E. Hinds et al.) - Soon: ThO – currently taking data - Molecules, molecular ions, solids: PbO, PbF, HBr, BaF, HgF, GGG, Gd2Ga5O12 etc. - dGGG ~ < 10-24 ecm - d < 1.8 . 10-19 (90%) ecm from g-2 - d < 1.7 . 10-17 (90%) ecm from Z Diamagnetic atoms also contribute to such limits! Tl, YbF limits together, courtesy T. Chupp (2013) P. Fierlinger – MeNu2013 The ACME experiment - - 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 10-28 ecm /day P. Fierlinger – MeNu2013 Figures: J. Doyle 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 10-27 ecm atoms ~ < 1.10-29 ecm (ThO, 199Hg, 129Xe) 6 years: nEDM ~ few 10-28 ecm atoms - hard to predict ... Note: my nEDM time estimate stayed constant since 2009 P. Fierlinger – MeNu2013 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.) 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, reaccelerated high brightness beam with extremely well known time structure for in-beam EDM? S. Mayer et al., NIM A 608 (2009) 434–439 New concepts? Supersymmetry More sources of CP violation ~ EDMs at 1 loop level dn 1026 1028 ecm 2 d Hg 1 T eV 2 10 ecm M 27 Boson coupling Hg EDM ~ exp. Limit! MSSM for M = 1 TeV, tan =3 Consequences - small phases: problem for baryogenesis - cancellations: requires tuning - heavy masses P. Fierlinger – MeNu2013 Higgsino mass phase Pospelov, Ritz, Ann. Phys. 318(2005)119 MSSM example: