1. Mesure du moment électrique dipolaire du neutron Oscar Naviliat-Cuncic LPC-Caen et Université de Caen Basse-Normandie Journée de la division Champs et Particules de la SFP « Le Futur de la Physique des Saveurs » Jussieu, janvier 2007

2. 2SFP-LPNHE, 27 janvier 2007 O.Naviliat-Cuncic: naviliat@lpccaen.in2p3.fr Plan role of low energy precision measurements measurement principle experimental sensitivity role of UCNs and their sources present limit on the neutron EDM the world competition toward a new nEDM measurement the new UCN source at PSI R&D activities (materials, detectors, magnetometry) plans and schedule

3. 3SFP-LPNHE, 27 janvier 2007 O.Naviliat-Cuncic: naviliat@lpccaen.in2p3.fr Potential of low precision measurements Assuming CPT: CP-violation = T-violation In systems or processes without strangeness, the effects due to the CKM CP-violation are strongly suppressed (nEDM < 10 -(31-33) ecm; correlations in beta decay <10 -10 ) Huge window to search for new physics! (without being affected by SM backgrounds) EDMs of quantum systems are very sensitive probes

4. 4SFP-LPNHE, 27 janvier 2007 O.Naviliat-Cuncic: naviliat@lpccaen.in2p3.fr Permanent EDMs classical dipole interaction H = - (d ·E +  ·B) = - (d E +  B) · ŝ observables - spin S, unit vector ŝ - magnetic dipole moment:  =  ŝ - for an elementary QM system: d = d ŝ transformations under T and P B and ŝ behave identically but not E and ŝ if d ≠ 0 : T and P are violated

5. 5SFP-LPNHE, 27 janvier 2007 O.Naviliat-Cuncic: naviliat@lpccaen.in2p3.fr EDM measurements upper limits have been obtained for: e, , , p, n, , atoms, molecules new projects and approaches are being considered for: e, , n, d, radioactive nuclei, atoms very active field ! complementary constraints (ex. SUSY phases) Any new mechanism for CP violation in the quark sector has in particular to pass the neutron EDM test [ see e.g. R. Barbieri et al. NP B449 (1995) 437; hep-ph/9504373]

6. 6SFP-LPNHE, 27 janvier 2007 O.Naviliat-Cuncic: naviliat@lpccaen.in2p3.fr Neutron EDM evolution Requirements for higher sensitivity Experimental advantages  no electric charge  long lifetime  storage of UCNs possible  larger densities  further control of systematics

7. 7SFP-LPNHE, 27 janvier 2007 O.Naviliat-Cuncic: naviliat@lpccaen.in2p3.fr Measurement principle prepare a sample of polarized neutrons make a  /2 spin flip (“start clock”) allow free spin precession in parallel B and E static fields make a  /2 spin flip (“stop clock”) analyze direction of neutron spin 4 3 2 1 Free precessio n... Apply  /2 spin flip pulse... “Spin up” neutron... Second  /2 spin flip pulse. B E look at energy (frequency) shift under field inversion:  = h |  | = 4Ed n Ramsey method of Separated Oscillating Fields

8. 8SFP-LPNHE, 27 janvier 2007 O.Naviliat-Cuncic: naviliat@lpccaen.in2p3.fr Sensitivity figure  : slope on resonance curve (“visibility”) T : free precession time E : electric field strength N : total number of detected neutrons (N ~  V t mes ) high sensitivity requires - long precession times - large neutron densities

9. 9SFP-LPNHE, 27 janvier 2007 O.Naviliat-Cuncic: naviliat@lpccaen.in2p3.fr What are Ultra-Cold Neutrons ? definition neutrons which are reflected at any angle of incidence (the neutron kinetic energy is smaller than the “ Fermi potential ” of the surface) n ≈ 800 Å ; v n ≈ 5 m/s T n ≈ 2 mK ; E n ≈ 130 neV

10. 10SFP-LPNHE, 27 janvier 2007 O.Naviliat-Cuncic: naviliat@lpccaen.in2p3.fr The UCN source at ILL the only multi-user UCN source in operation high flux reactor (thermal power: 58.3 MW) thermal n-flux: 1.5 × 10 15 n/s/cm 2 cold neutron source: 20 l of LD 2 at 25K vertical neutron guide 13m, 7×7 cm 2, ( 58 Ni coated) UCN source: rotating turbine UCN density at experiment:  = 20 /cm 3

11. 11SFP-LPNHE, 27 janvier 2007 O.Naviliat-Cuncic: naviliat@lpccaen.in2p3.fr Sussex-RAL-ILL experiment (P.G. Harris et al. PRL 82(1999) 904) V = 20 l B = 10 mG, L = 30 Hz E = 4.5 - 11.0 kV/cm T = 120 - 140 s  (d n ) = 5×10 -26 ecm / 50 days cycle best achieved sensitivity with 50% duty cycle

12. 12SFP-LPNHE, 27 janvier 2007 O.Naviliat-Cuncic: naviliat@lpccaen.in2p3.fr Final Sussex-RAL-ILL result (C.A. Baker et al. PRL 97(2006) 131801) | d n | < 2.9 x 10 -26 ecm (90% CL) use of 199 Hg co-magnetometer d( 199 Hg) < 8.7 × 10 -28 ecm 50 pT

13. 13SFP-LPNHE, 27 janvier 2007 O.Naviliat-Cuncic: naviliat@lpccaen.in2p3.fr World competition (cryo exps) cryo UCN sources in super-fluid He superconducting Pb shields SQUID magnetometry full in LHe experiments (Sussex-RAL-ILL-Kure) also project in preparation in Japan

14. 14SFP-LPNHE, 27 janvier 2007 O.Naviliat-Cuncic: naviliat@lpccaen.in2p3.fr Toward a new EDM measurement G. Ban, Th. Lefort, O. Naviliat-Cuncic, G. Rogel Laboratoire de Physique Corpusculaire, Caen, France K. Bodek, St. Kistryn, M. Kuzniak, J. Zejma Institute of Physics, Jegellonian University, Cracow, Poland N. Khomutov, B.M. Sabirov Joint Institute of Nuclear Reasearch, Dubna, Russia P. Knowles, M. Rebetez, A. Weis Departement de Physique, Universit é de Fribourg, Fribourg, Switzerland C. Plonka Institut Laue-Langevin, Grenoble, France G. Quéméner, D. Rebreyend, S. Roccia, M. Tur Laboratoire de Physique Subatomique et de Cosmologie, Grenoble, France M. Daum, R. Henneck, S. Heule, M. Kasprzak, K. Kirch, A. Knecht, A. Pichlmaier Paul Scherrer Institute, Villigen, Switzerland

15. 15SFP-LPNHE, 27 janvier 2007 O.Naviliat-Cuncic: naviliat@lpccaen.in2p3.fr Specific features and steps Push the room-temperature, in-vacuum technique to a new limit At ILL (since 2004): Work with the RT spectrometer of Sussex-RAL-ILL (learn, repair, measure, test, recuperate, ….) Improve magnetic field measurement Improve magnetic field stability and homogeneity Improve overall stability and control At PSI (at new UCN source): Increase statistics Implement new tools for control of systematics Build new spectrometer Final goal: improve by two orders of magnitude the present level of sensitivity

16. 16SFP-LPNHE, 27 janvier 2007 O.Naviliat-Cuncic: naviliat@lpccaen.in2p3.fr Operation at ILL General operation under control Many failures, reparations, replacements New full test measurement for end 2007 (not for a new EDM value)

17. 17SFP-LPNHE, 27 janvier 2007 O.Naviliat-Cuncic: naviliat@lpccaen.in2p3.fr Spallation UCN source at PSI 590 MeV, 2 mA, proton beam pulsed (1% duty cycle) spallation target: Pb moderators: D 2 O (20-80 K) UCN source: SD 2 (30 l, 8K) storage volume: 2-3 m 3 expected density:  = 2-3000 /cm 3 starting operation end 2008

18. 18SFP-LPNHE, 27 janvier 2007 O.Naviliat-Cuncic: naviliat@lpccaen.in2p3.fr MC simulations and materials Storage time with chamber at 1m above beam line (required the inclusion of UCN physics into GEANT4 – P. Fierlinger and others, NIMA 552(2005)513 ) present system: 1 Chamber/Electrode Quartz/DLC:19 Si3N4/DLC:29 Diam./DLC:33 Diam./Diam.:35

19. 19SFP-LPNHE, 27 janvier 2007 O.Naviliat-Cuncic: naviliat@lpccaen.in2p3.fr Detector tests and spin analysis GEMDoped glass scintillator GS10 analyzers Spin flipper GS10 UCN

20. 20SFP-LPNHE, 27 janvier 2007 O.Naviliat-Cuncic: naviliat@lpccaen.in2p3.fr Magnetometry magnetic resonance + optical preparation & detection 1 magnetometer (OPM) needs 25  W 1 laser delivers >10 mW 1 laser = many sensors Cs Laser Optically Pumped magnetometer Intrinsic sensitivity demonstrated: residual field fluctuations at 40fT for stabilized OPM

21. 21SFP-LPNHE, 27 janvier 2007 O.Naviliat-Cuncic: naviliat@lpccaen.in2p3.fr Discovering a magnetic anomaly… Set of 8 Cs OPM Field variations correlated with movement of the UCN shutter seen at different locations: …hunt the magnetic impurity!

22. 22SFP-LPNHE, 27 janvier 2007 O.Naviliat-Cuncic: naviliat@lpccaen.in2p3.fr Phases and schedule 200720082009201020112012 Improvements Sussex-RAL spectro Mesure with Sussex-RAL spectro Design new spectrometerConstruction new spectrometer Mesure with new spectro Phase 1 Phase 2 -Operation of UCN source at PSI phase 0: R&D at ILL ( … now) phase 1: measurement at PSI with old improved spectro phase 2: measurement at PSI with new spectro