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Improved search for the neutron electric dipole moment

Improved search for the neutron electric dipole moment. Improved search for the neutron electric dipole moment. Philipp Schmidt –Wellenburg on behalf of the nEDM collaboration. Philipp Schmidt –Wellenburg on behalf of the nEDM collaboration. SM expectation:. Sakharov criteria.

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Improved search for the neutron electric dipole moment

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  1. Improved search for the neutron electric dipole moment Improved search for the neutron electric dipole moment Philipp Schmidt –Wellenburg on behalf of the nEDM collaboration Philipp Schmidt –Wellenburg on behalf of the nEDM collaboration

  2. SM expectation: Sakharov criteria • Baryon number violation • C and CP violation • Thermal non-equilibrium Baryon asymmetry We live in a material world There is no evidence of Antimatter; Where has it gone? Observed: - n n vs. - B 10 B ~ 10 n g

  3. Symmetries and EDM P T Purcell and Ramsey, PR78(1950)807; Lee and Yang; Landau

  4. Symmetries and EDM P T A nonzero particle EDM violates P, T and, assuming CPT conservation, also CP. Purcell and Ramsey, PR78(1950)807; Lee and Yang; Landau

  5. CP-odd sources Energy fundamental CP-odd phases TeV , dq’,dq’,w de QCD qq/qe interaction nuclear nEDM gNN e-N interaction atomic EDM of Tl(paramagnetic) EDM of Hg(diamagnetic) Adapted from:A. Ritz, NIMA 611 (2009) 117

  6. nEDM is a test of flavor diagonal CP (so far CP only appeared in of diagonal elements of the CKM Matrix) background free search for new physics CP violation of the neutron contribute to: explaining baryogenesis problem(Sakharov criteria) magical fine adjustment of QCD θ-term (θ < 10-9) confining SUSY (MSSM) parameter spacecomplementary to high energy physics (LHC) The role of an neutron EDM M.J. Ramsey-Musolf, NIMA 611 (2009) 111

  7. +  < 1μm A brief history of nEDM searches Aimed at sensitivities at PSI:Intermediate: dn < 5 x 10-27 e cm (95% C.L.)Final: dn< 5 x 10-28 e cm(95% C.L.) ~ 50 years First Last Smith, Purcell, Ramsey dn < 5 x 10–20 e cmPR 108 (1957) 120 RAL-Sussex-ILL dn < 2.9 x 10–26e cmC.A.Baker et al., PRL 97 (2006) 131801

  8. The measurement principle Measure the difference of precession frequencies for parallel/anti-parallel fields: for dn<10-26 ω< 60 nHz

  9. Ramsey resonance curve Sensitivity: • Visibility of resonanceE Electric field strengthT Time of free precessionN Number of neutrons The Ramsey technique The Ramsey technique of separated oscillating fields “Spin up” neutron... B0↑ Apply /2 spin flip pulse... B0↑ + Brf Free precessionat ωL B0↑ Second /2 spin flip pulse. B0↑ + Brf

  10. gravity 102 neV/m V strong VF 350 neV ↔ 8 m/s ↔ 500 Å ↔ 3 mK magnetic 60 neV/T storage properties are material dependent E. Fermi, 1946 ,Ya. B. Zeldovich Sov. Phys. JETP 9, 1389 (1959) Ultracold neutrons (UCN) storable neutrons (UCN)

  11. PSI UCN source UCN storage volume Neutron shutter Neutron guide to experiments UCN density: 1000/cm3 1m UCN convertor (solid D2) Protons Spallation target En~MeV D2O moderator Neutrons thermalized to 25 meV

  12. PSI UCN beamline • Source commissioning started fall 2009 • nEDM setting up since middle of 2009 • Full proton beam (590 MeV, 2.2 mA, 1% duty cycle e.g. 8s/800s) n nEDM

  13. ILL(phase I) PSI(phase II) RAL – Sussex – ILL apparatus on loan

  14. Apparatus High voltage lead Vacuum chamber Precession chamberwhere neutrons precesses Electrode (upper) B E E~12 kV/cm B=1 T Magnetic field coilsB0-correction coils Switchto distribute the UCNs todifferent parts of the apparatus Spin analyzer 5T magnetto spin polarize UCNs Neutron detector

  15. Measuring frequencies with UCN • changing polarity every ~ 400 s • comparing frequency +/- polarity • aimed at sensitivity ω  60 nHz Sensitivity: 50 pT

  16. Monitoring of B-field drifts 4-layer Mu-metal shieldshields experiment fromexternal magnetic fields Cesium magnetometer Precession chamberwhere mercury precesses Electrode (upper) Photomultiplier tuberead mercury light (UV) Mercury lamp(readout mercury) Hg polarizing system Magnetic field coilsB0-correction coils + Active B-field compensation (surrounding field compensation SFC)

  17. Corrected measurement A Cesium magnetometer areawill allow measure field gradients 50 pT Corrected with Hg magentometer

  18. Cesium (ILL) • Mercury (ILL) • Cesium (PSI) w SFC Sensitivities and magnetic stability Allan standard deviation of magnetic field • Steps to increase magnetic stability • Stability of the magnetic shield • Degaussing • Thermal effects • Mechanical effects • Surrounding field compensation (SFC) • Replacement of metals • Non-metal electrodes • Plastic shutters (Hg and neutron)

  19. Known systematic effects After 2 years, statistics & systematics dn= 0: |dn| < 5 x 10-27 e cm (95% C.L.) or, e.g., dn= 1.3 x 10-26 e cm (5σ) PRL 97, 131801 (2006)

  20. n2EDM shield – conceptual study Phase III dn< 5 x 10-28 e cm(95% C.L.)

  21. Conclusion • The apparatus was successfully moved from ILL to the Paul Scherrer Institut • The stability of the magnetic situation is being improved to profit in full scale of the increased UCN density • The study and control of systematic effects has improved compared to the original experiment • First neutrons will be welcomed end of year, the spectrometer will be ready Ready for neutrons

  22. Physikalisch Technische Bundesanstalt, Berlin Laboratoire de Physique Corpusculaire, Caen Institute of Physics, Jagiellonian University, Cracow Henryk Niedwodniczanski Inst. Of Nucl. Physics, Cracow Joint Institute of Nuclear Reasearch, Dubna Département de physique, Université de Fribourg, Fribourg Excellence Cluster Universe, Garching Laboratoire de Physique Subatomique et de Cosmologie, Grenoble Biomagnetisches Zentrum, Jena Katholieke Universiteit, Leuven Inst. für Kernchemie, Johannes-Gutenberg-Universität, Mainz Inst. für Physik, Johannes-Gutenberg-Universität, Mainz Technische Universität, München Paul Scherrer Institut, Villigen Eidgenössische Technische Hochschule, Zürich M. Burghoff, S. Knappe-Grüneberg, A. Schnabel, L. Trahms G. Ban, Th. Lefort, Y. Lemiere, E. Pierre, G. Quéméner K. Bodek, St. Kistryn, J. Zejma A. Kozela N. Khomutov P. Knowles, A.S. Pazgalev, A. Weis P. Fierlinger, B. Franke1, M. Horras1, F. Kuchler, G. Petzoldt D. Rebreyend , G. Pignol G. Bison S. Roccia, N. Severijns, N.N. G. Hampel, J.V. Kratz, T. Lauer, C. Plonka-Spehr, N. Wiehl, J. Zenner1 W. Heil, A. Kraft, Yu. Sobolev2 I. Altarev, E. Gutsmiedl, S. Paul, R. Stoepler Z. Chowdhuri, M. Daum, M. Fertl, R. Henneck, B. Lauss, A. Mtchedlishvili, P. Schmidt-Wellenburg, G. Zsigmond K. Kirch1, F. Piegsa The Neutron EDM Collaboration also at: 1Paul Scherrer Institut, 2PNPI Gatchina

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