P. Schmidt-Wellenburg Time and Matter, Montenegro, 06. Oct Slide 1 Improved search for the neutron electric dipole moment Philipp Schmidt –Wellenburg on behalf of the nEDM collaboration Improved search for the neutron electric dipole moment Philipp Schmidt –Wellenburg on behalf of the nEDM collaboration

P. Schmidt-Wellenburg Time and Matter, Montenegro, 06. Oct Slide 2 Baryon asymmetry We live in a material world There is no evidence of Antimatter; Where has it gone? Sakharov criteria 1.Baryon number violation 2.C and CP violation 3.Thermal non-equilibrium vs. SM expectation: Observed: 10 ~    n B nn B

P. Schmidt-Wellenburg Time and Matter, Montenegro, 06. Oct Slide 3 P Purcell and Ramsey, PR78(1950)807; Lee and Yang; Landau T Symmetries and EDM

P. Schmidt-Wellenburg Time and Matter, Montenegro, 06. Oct Slide 4 P Purcell and Ramsey, PR78(1950)807; Lee and Yang; Landau T Symmetries and EDM A nonzero particle EDM violates P, T and, assuming CPT conservation, also CP.

P. Schmidt-Wellenburg Time and Matter, Montenegro, 06. Oct Slide 5 CP-odd sources fundamental CP-odd phases Energy dede TeV QCD nuclear atomic d q , d q’, d q’,w g  NN nEDM qq/qe interaction EDM of Tl (paramagnetic) EDM of Hg (diamagnetic) e-N interaction Adapted from: A. Ritz, NIMA 611 (2009) 117

P. Schmidt-Wellenburg Time and Matter, Montenegro, 06. Oct Slide 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 < ) – confining SUSY (MSSM) parameter space complementary to high energy physics (LHC) The role of an neutron EDM M.J. Ramsey-Musolf, NIMA 611 (2009) 111

P. Schmidt-Wellenburg Time and Matter, Montenegro, 06. Oct Slide 7 ++ < 1μm A brief history of nEDM searches RAL-Sussex-ILL d n < 2.9 x 10 –26 e cm C.A.Baker et al., PRL 97 (2006) Smith, Purcell, Ramsey d n < 5 x 10 –20 e cm PR 108 (1957) 120 FirstLast ~ 50 years Aimed at sensitivities at PSI: Intermediate: d n < 5 x e cm (95% C.L.) Final: d n < 5 x e cm (95% C.L.)

P. Schmidt-Wellenburg Time and Matter, Montenegro, 06. Oct Slide 8 The measurement principle Measure the difference of precession frequencies for parallel/anti-parallel fields: for d n <  ω < 60 nHz

P. Schmidt-Wellenburg Time and Matter, Montenegro, 06. Oct Slide 9 The Ramsey technique Free precession at ω L Apply  /2 spin flip pulse... “Spin up” neutron... Second  /2 spin flip pulse. The Ramsey technique of separated oscillating fields B 0↑ B 0↑ + B rf B 0↑ B 0↑ + B rf Ramsey resonance curve Sensitivity:  Visibility of resonance EElectric field strength TTime of free precession NNumber of neutrons

P. Schmidt-Wellenburg Time and Matter, Montenegro, 06. Oct Slide 10 Ultracold neutrons (UCN) storable neutrons (UCN) V E. Fermi, 1946, Ya. B. Zeldovich Sov. Phys. JETP 9, 1389 (1959) storage properties are material dependent 350 neV ↔ 8 m/s ↔ 500 Å ↔ 3 mK magnetic  60 neV/T magnetic  60 neV/T gravity 102 neV/m gravity 102 neV/m strong V F strong V F

P. Schmidt-Wellenburg Time and Matter, Montenegro, 06. Oct Slide 11 PSI UCN source Protons Spallation target E n ~MeV D 2 O moderator Neutrons thermalized to 25 meV 1m Neutron shutter UCN storage volume Neutron guide to experiments UCN density: 1000/cm 3 UCN convertor (solid D 2 )

P. Schmidt-Wellenburg Time and Matter, Montenegro, 06. Oct Slide 12 nn 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) nEDM PSI UCN beamline

P. Schmidt-Wellenburg Time and Matter, Montenegro, 06. Oct Slide 13 RAL – Sussex – ILL apparatus on loan ILL (phase I) PSI (phase II)

P. Schmidt-Wellenburg Time and Matter, Montenegro, 06. Oct Slide 14 Apparatus 5T magnet to spin polarize UCNs Switch to distribute the UCNs to different parts of the apparatus Spin analyzer Neutron detector Precession chamber where neutrons precesses Vacuum chamber Magnetic field coils B 0 -correction coils Electrode (upper) High voltage lead E B E~12 kV/cm B=1  T

P. Schmidt-Wellenburg Time and Matter, Montenegro, 06. Oct Slide 15 Measuring frequencies with UCN Sensitivity: changing polarity every ~ 400 s comparing frequency +/- polarity aimed at sensitivity  ω  60 nHz 50 pT

P. Schmidt-Wellenburg Time and Matter, Montenegro, 06. Oct Slide 16 Monitoring of B-field drifts Mercury lamp (readout mercury) Hg polarizing system Photomultiplier tube read mercury light (UV) Precession chamber where mercury precesses 4-layer Mu-metal shield shields experiment from external magnetic fields Magnetic field coils B 0 -correction coils Electrode (upper) Cesium magnetometer + Active B-field compensation (surrounding field compensation SFC)

P. Schmidt-Wellenburg Time and Matter, Montenegro, 06. Oct Slide 17 Corrected measurement Corrected with Hg magentometer 50 pT A Cesium magnetometer area will allow measure field gradients

P. Schmidt-Wellenburg Time and Matter, Montenegro, 06. Oct Slide 18 Sensitivities and magnetic stability Cesium (ILL) Mercury (ILL) Cesium (PSI) w SFC Steps to increase magnetic stability 1.Stability of the magnetic shield Degaussing Thermal effects Mechanical effects 2.Surrounding field compensation (SFC) 3.Replacement of metals Non-metal electrodes Plastic shutters (Hg and neutron) Allan standard deviation of magnetic field

P. Schmidt-Wellenburg Time and Matter, Montenegro, 06. Oct Slide 19 Known systematic effects Effect Shift (see Ref.) [ e cm] σ (see Ref.) [ e cm] σ (at PSI) [ e cm] Door cavity dipole Other dipole fields Quadrupole difference v  E translational v  E rotational Second-order v  E Hg light shift (geo phase) Hg light shift (direct) Uncompensated B drift Hg atom EDM Electric forces Leakage currents ac fields Total PRL 97, (2006) After 2 years, statistics & systematics d n = 0: |d n | < 5 x e cm (95% C.L.) or, e.g., d n = 1.3 x e cm (5σ)

P. Schmidt-Wellenburg Time and Matter, Montenegro, 06. Oct Slide 20 n2EDM shield – conceptual study Phase III d n < 5 x e cm (95% C.L.)

P. Schmidt-Wellenburg Time and Matter, Montenegro, 06. Oct Slide 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

P. Schmidt-Wellenburg Time and Matter, Montenegro, 06. Oct Slide 22 also at: 1 Paul Scherrer Institut, 2 PNPI Gatchina The Neutron EDM Collaboration 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. Franke 1, M. Horras 1, 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. Zenner 1 W. Heil, A. Kraft, Yu. Sobolev 2 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. Kirch 1, F. Piegsa 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

P. Schmidt-Wellenburg Time and Matter, Montenegro, 06. Oct Slide 23 BACKUP

P. Schmidt-Wellenburg Time and Matter, Montenegro, 06. Oct Slide 24 The nEDM collaboration

P. Schmidt-Wellenburg Time and Matter, Montenegro, 06. Oct Slide 25 4-layer magnetic shield Moving the shieldMechanical shocks

P. Schmidt-Wellenburg Time and Matter, Montenegro, 06. Oct Slide 26 Magnetic field requirements Δω = ω  - ω  = 2d n (E  +E  )/ħ + 2μ n (B  -B  )/ħ statistical sensitivity: σ(d n ) ~ 3 × e cm per cycle ( E ↑↑ and E ↑↓ ) ~ 400 s B field requirement: σ(ΔB) ~ 200 fT per Ramsey measurement ( ~ 100 s) Measuring an d n < e cm requires to measure a Δω < 30 nHz !

P. Schmidt-Wellenburg Time and Matter, Montenegro, 06. Oct Slide 27 Magnetic shocks The apparatus is in the vicinity of several experimental magnets Fast changes of the magnetic field (O( μT)) can lead to irreversible changes of the field seen by neutrons The behavior of these shocks where tested with SFC coils An active surrounding field compensation will minimize this effect  shock -/+ shock + shock Residual shock signal Shield magnetization Irreversible shield magnetization + B [nT]

P. Schmidt-Wellenburg Time and Matter, Montenegro, 06. Oct Slide 28 The Ramsey method in a double chamber ħ ω/2 = ±μB +d n E E ħ ω/2 = ±μB -d n E B Ramsey method: (e.g. with two parallel chambers) ħ ω/2 = ±μB Δω = ω  - ω  = 2d n (E  +E  )/ħ + 2μ n (B  -B  )/ħΔω = ω  - ω  = 4d n (E )/ħ

P. Schmidt-Wellenburg Time and Matter, Montenegro, 06. Oct Slide 29 Leakage current 1.Changing the polarity of the high voltage will change the direction of the leakage current, and hence the magnetic field produced by these currents 2.Most contribution of the leakage currents cancel out, not so j φ. jrjr jrjr jφjφ jφjφ jφjφ jzjz Leakage currents are caused by the high voltage and appear along the surface of the insulator ring. A leakage current of 1 nA produces a false edm of 2 × e cm

P. Schmidt-Wellenburg Time and Matter, Montenegro, 06. Oct Slide 30 Leakage current measurement Current (nA) Time (h) 0.75pA 4 pA FEMTO 1.Monitoring of leakage currents on ground electrode 2.Combination of protection circuit and highly sensitive current/voltage amplifier I Leak (nA) U HV (kV) I Leak ≤ 0.5 nA σ ≤ 0.1 × e cm

P. Schmidt-Wellenburg Time and Matter, Montenegro, 06. Oct Slide 31 Uncompensated B Drift Experimental tests and improvements 1.Cs magnetometer can measure dipole field 2.Charging current of HV can be adapted σ = 0.9 × e cm

P. Schmidt-Wellenburg Time and Matter, Montenegro, 06. Oct Slide 32 Electric dipole moment and physics Thallium, YbF Atom/Molekül Niveau CP von Teilchen zu Atomen Kern Niveau NNNN WW Schiff Moment Quecksilber Higgs, SUSY, Left/Right Sarke CP Feldtheorie CP Modell  GG Neutron Nukleon Niveau Elektron/Quark Niveau dqdq ~ dede eN-WW g  NN ++ --

P. Schmidt-Wellenburg Time and Matter, Montenegro, 06. Oct Slide 33 PSI UCN production beam line Proton energy: 590 MeV Beam current: 2 mA Power: 1.3 MW Proton energy: 590 MeV Beam current: 2 mA Power: 1.3 MW