electric dipole moments (EDM) - PowerPoint Presentation

1. electric dipole moments (EDM) Hans ströher I Matter and the universe days 2019 (desy)Static and oscillating

2. Electric dipole momentsIntroductionEDM: a permanent separation of positive and negative charge (vector along spin direction)Fundamental property of particles (like mass, charge, magnetic moment)Existence of EDM only possible if violation of time reversal and parity symmetry; note:Close connection to matter-antimatter asymmetry of UniverseSensitive to new physics beyond the Standard ModelAxion field (coupling to gluons) leads to oscillating EDM

3. Electric dipole momentsExperimental effortOriginal by Klaus Jungman

4. Electric dipole momentsMeasurements – status and prospectspCurrent proton limit > neutron;only indirect measurement (199Hg)New: charged particles (proton, deuteron …)Potentially highest sensitivityIdentification of source requires neutron and proton (maybe even deuteron …)

5. Electric dipole momentsMeasurement principle (charged particles)Thomas-BMT eq.:Ideal situation: B = 0, magic momentum  WMDM = 0 („frozen spin“)Longitudinally polarized beam in storage ringRadial electric field interacting with EDM (torque)Observable: slow rotation of spin direction ( polarimetry)

6. Electric dipole momentsSensitivitiesStatistical sensitivity (one cycle):10.000 cycles (w/ parameters of table):Challenge:Identify and suppress all systematic errors to the same level!

7. Electric dipole momentsSystematic errors – one exampleMajor source: radial magnetic field Br mimics EDM, if m Br ~ d ErOrder of magnitude estimate:assume d = 10-29 e cm, Er = 10 MV/mCorresponding magnetic field Br:Potential solution:Use two beams running clockwise and counter-clockwise Separation of the two beams is sensitive to Br!

8. Electric dipole momentsVision – a dedicated precision pEDM storage ringElectrostatic ring (at least 4 beam bunches)Running at magic momentum (p = 0.7 GeV/c)Counter-rotating beams (simultaneously, same orbit)  many systematic effects cancel Many open questions, e.g.:Intensity and spin coherence timeInjection, phase space cooling of the beamsPolarimetry, orbit control, shielding, … General: ideal  realistic machine (tolerances)Staged approach

9. Staged approachPage 9Electric dipole momentsCOSY

10. Electric dipole momentsStage-0: recent achievements at COSY (JEDI collaboration)Precise determination of spin tunePR ST-AB (2014), PRL (2015)Long spin coherence time PRL (2016)Phase-lock of spin precession PRL (2017)Polarimeter developmentBeam instrumentationRF-Wien filter developmentCOSY is world-wide unique to perform these measurements

11. Electric dipole momentsStage-0: recent achievements at COSY (JEDI collaboration)Precise determination of spin tunePR ST-AB (2014), PRL (2015)Long spin coherence time PRL (2016)Phase-lock of spin precession PRL (2017)Polarimeter developmentBeam instrumentationRF-Wien filter developmentCOSY is world-wide unique to perform these measurements

12. Electric dipole momentsStage-1: precursor experiment at COSYRF Wien FilterCOSYWien FilterCOSY (magnetic storagering)  spin precession;use of deuteron beamsProblem: no EDM effectRF Wien Filter:RF-fields such that forward-backward effect does not cancelSensitivity to EDMFirst-ever deuteron EDM measurementStatistical sensitivity 10-(23-24) e cm; systematics: imperfections, alignment, …  limit: ~ 10-19 e cm systematics: imperfections, alignment, …  limit: ~ 10-19 e cm invariant spin axis: d = 0 d > 0EDM (or a field in x): rotates in x-direction (...) 2D map … should have minimum at (0,0) d = 0 or away from (0,0) d > 0Exptl. data (Dec.2018)?

13. Electric dipole momentsStage-2: prototype ring30 MeV all-electric p ringStorage timeCW/CCW operationSpin coherence timePolarimetry Phase space coolingmp effectsOption: add B-field, 45 MeVpEDM measurement Possible host: COSYInevitable next step

14. Electric dipole momentsStage-3: precision EDM ringAll-electric deflectionMagic momentum (p = 701 MeV/c)Simultaneous CW/CCW beamsPhase-space cooled beamsLong spin coherence time (> 1000 s)Non-destructive precision polarimetry Optimum orbit control Optimum shielding of external fieldsControl of residual (intentional) Br field„Holy Grail“ of storage rings (largest ever conceived)

15. Electric dipole momentsStaged approachpStep 1:PrecursorStep 2:PrototypeStep 3:Final ringNow5 yrs10 yrsSubmission to ESPP Update

16. Interaction of coherently oscillating axion DM field with gluons … oEDMPage 16static EDM (see above)Electric dipole moments - oscillatingStatic EDM: accumulation in „frozen spin“ conditionOscillating EDM: spin precesses, but oEDM flip  right frequency: accumulationfrequency (axion mass) not known  resonance scanPhase unknownnow: oscillating EDMOscillating EDM easier to detect (resonance)Proof-of-principle possible at COSYAxion (DM) / oEDM: additional science case for CPEDM

17. 00 Month 2018Page 17Electric dipole momentsSummaryElectrostatic storage rings offer a unique possibility to search for important new physics (EDM, DM)Ongoing: precursor experiment at COSY (RF Wien filter)Next step: prototype ring (design study under preparation)Long-term vision: precision storage ring (CW/CCW, magic momentum)Projects discussed in the framework of Physics Beyond Colliders (PBC) at CERNInput for update of European Strategy for Particle Physics (ESPP)

18.

19. Experimental EDM limits Electric dipole moments

20. Experimental EDM limits Electric dipole moments

21. Why so many (different) experiments? ExperimentsUltimate goalSourcesTheoretical analysisElectric dipole moments

22. Dark Matter – accessible frequency/mass range Electric dipole moments