The n EDM experiment at PSI 1 Physics

The n. EDM experiment at PSI 1 Physics case 2 Status of the running EDM experiment 3 n 2 EDM 4 The 3 He project at ILL Guillaume Pignol , groupe UCN Conseil scientifique LPSC, 15/11/2013 1

The n. EDM If nonzero, EDM violates T, thus CP 2

n. EDM to probe generic BSM CP violation 3

n. EDM to probe electroweak baryogenesis Sakharov conditions at electroweak phase transition 1 Departure from thermal equilibrium requires BSM scalar sector to get a strong first order transition. May or may not be accessible at the LHC 2 CP violation requires BSM physics, accessible by the next generation of EDM experiments 3 Violation of B conservation SM sphaleron transitions in the symmetric phase 4

Minimal electroweak baryogenesis Makes the phase transition strongly first order CP violation Prediction for 126 Ge. V Higgs n. EDM = 1. 3 x 10 -26 e cm (Current limit at 3 x 10 -26 e cm) 5

The quest for EDMs 6

The PSI EDM collaboration M. Burghoff, S. Knappe-Grüneberg, A. Schnabel, J. Vogt Physikalisch Technische Bundesanstalt, Berlin G. Ban, V. Hélaine, T. Lefort, Y. Lemiere, G. Quéméner Laboratoire de Physique Corpusculaire, Caen K. Bodek, M. Rawlik, G. Wyszynski, J. Zejma Institute of Physics, Jagiellonian University, Cracow A. Kozela Henryk Niedwodniczanski Inst. Of Nucl. Physics, Cracow N. Khomutov Joint Institute of Nuclear Reasearch, Dubna M. Kasprzak, H. C Koch, A. Weis, Z. Grujic Département de physique, Université de Fribourg, Fribourg Y. Kermaïdic , G. Pignol, D. Rebreyend, B. Clément, S. Afach Lab. de Physique Subatomique et de Cosmologie, Grenoble N. Severijns, P. Pataguppi Katholieke Universiteit, Leuven W. Heil S. Roccia, G. Bison , Z. Chowdhuri, M. Fertl, B. Lauss, S. komposch D. Ries, P. Schmidt-Wellenburg, G. Zsigmond Inst. für Kernchemie, Johannes-Gutenberg-Universität, Mainz B. Franke, K. Kirch, J. Krempel, F. Piegsa, D. Zhu Biomagnetisches Zentrum, Jena Centre de Spectrométrie Nucléaire et de Spectrométrie de Masse, Paris Paul Scherrer Institut, Villigen Eidgenössische Technische Hochschule, Zürich RED: Ph. D students, GREEN: spokespersons 7

The n. EDM experiment at PSI 1 Physics case 2 Status of the running EDM experiment UCN source Systematic effects Statistical sensitivity 3 n 2 EDM 4 The 3 He project at ILL 8

The PSI UCN source, availability Paul Scherrer Institute, Zurich 100000 proton pulses 10000 100 10 600 Me. V, 2. 2 m. A 2010 2011 2012 2013 9

The PSI UCN source, intensity Paul Scherrer Institute, 25 l volume Zurich UCN density measured at West 1 23 UCN/cm 3 Same vessel used at ILL PF 2 4. 7 UCN/cm 3 10

The PSI UCN source, recent progress Paul Scherrer Institute, Zurich Recently measured thermal neutron flux agrees with calculations. Improvement by factor of ~15 in UCN output can still be gained, a goal actively pursued by the PSI group. 11

The Ramsey method “Spin up” neutron. . . Apply /2 spin-flip pulse. . . Applied pulse frequency [Hz] Free precession. . . T ~ 200 s Second /2 spinflip pulse polarization electric field precession time counts 12

OILL spectrometer 13

Current n. EDM apparatus at PSI Shielded magnetic environment Homogeneity < 10 -3 B 0 = 1 µT Time stability < 10 -6 Electric field 150 k. V / 12 cm OILL apparatus moved from ILL to PSI in 2009 14

LPSC contributions B 0 stable current source Central DAQ module – version 2 hardware (completed sept 2012) software (to be delivered soon…) Mechanical parts of precession chamber DLC coated electrodes Hg light polarimeter (SDI) UCN shutter 15

The n. EDM experiment at PSI 1 Physics case 2 Status of the running EDM experiment UCN source Systematic effects Statistical sensitivity 3 n 2 EDM 4 The 3 He project at ILL 16

Systematic effects 17

Example: gravitational effect UCN gaz Same precession chamber Mercury gaz g Center of gravity height difference is R = fn / f. Hg depends on vertical gradients 18

Gravitational effect 19

Interpretation: measurement of the neutron magnetic moment RY A IN IM EL PR 20

Publications, R&D and byproducts Experimental study of 199 Hg spin anti-relaxation coatings Z. Chowdhuri et al, Applied Physics B (2013) 1. Development of a multifunction module for the neutron electric dipole moment experiment at PSI O. Bourrion, G. Pignol, D. Rebreyend, C. Vescovi, NIM A (2013) 278. Electric dipole moment searches: reexamination of frequency shifts for particles in traps G. Pignol, S. Roccia, Physical Review A 85 (2012) 042105. First observation of trapped high-field seeking ultracold neutron spin states M. Daum et al, Physics Letters B 704 (2011) 456. New constraints on Lorentz invariance violation from the neutron electric dipole moment I. Altarev et al, Europhysics Letters 92 (2010) 51001. Test of Lorentz invariance with spin precession of ultracold neutrons I. Altarev et al, Physical Review Letters 103 (2009) 081602. Neutron to mirror-neutron oscillations in the presence of mirror magnetic fields I. Altarev et al, Physical Review D 80 (2009) 032003. Direct Experimental Limit on Neutron–Mirror-Neutron Oscillations G. Ban et al, Physical Review Letters 99 (2007) 161603. 21

The n. EDM experiment at PSI 1 Physics case 2 Status of the running EDM experiment UCN source Systematic effects Statistical sensitivity 3 n 2 EDM 4 The 3 He project at ILL 22

Statistical sensitivity 23

Statistical sensitivity Winter shutdown Tests UCN source 24

The n. EDM experiment at PSI 1 Physics case 2 Status of the running EDM experiment 3 n 2 EDM 4 The ILL 3 He project 25

n 2 EDM, general concept Simultaneous measurement of the neutron frequency for both field configurations → means: two chambers with opposite electric field direction → insensitive to magnetic field drifts B 0 26

n 2 EDM, magnetic field control Magnetic field stability and homogeneity (B 0 = 1 µT) Movable coils system Movable vacuum tank - New passive cubic multilayer shield 5 layers, shielding factor ≈ 105, shield delivered in 2015 - Coils system (B 0, RF, correcting) new technique, field homogeneity 10 -5, no external field - Stabilized B 0 current source B 0 drift during precession < 10 -7 (100 f. T) - Active surrounding field compensation (SFC) reduce external field fluctuations and inhomogeneties Fixed multilayer passive magnetic shield - Shield degaussing residual field < 100 p. T + active 3 D field stabilization, thermohouse (built) Homogeneity < 10 -5 → Gradient < 1 p. T/cm Stability during precession < 10 -7 (100 f. T) 27

n 2 EDM, triple magnetometry • Mercury comagnetometers (cogradiometer) • Cesium vector magnetometers • External gradiometer (3 He) Hg Hg 28

n 2 EDM, designed statistical sensitivity work on improving (α, E, T, N) parameters Parameter Improvement factor Neutrons number N 5 Electric field E 1. 3 New electrodes geometry Visibility α 1. 25 Larger T 2 (field homogeneity) Precession time T ? Coating investigation (Diamond) Statistical sensitivity 8 Based on the current source performances Foreseen sensitivity 4 x 10 -26 e. cm / day Comment Better adaptation to the source (x 3) Two precession chambers (x 1. 5) 2 x 10 -27 e. cm / 4 years (starting in 2018) 29

n 2 EDM, possible LPSC participation • Improved stable current source for the n 2 EDM main coil Current ≈50 m. A, stability < 10 -7 • Mercury magnetometry: test bench at LPSC design and construction of the n 2 EDM comagnetometer ANR call 2014 30 k. E (current source) 120 k. E (Hg comag) 30

The n. EDM experiment at PSI 1 Physics case 2 Status of the running EDM experiment 3 n 2 EDM 4 The 3 He project at ILL 31

Probing Axion-like forces with polarized 3 He gs iγ 5 gp Champ pseudo-magnétique dépolarisant 32

The 3 He magnetic environment Reception du solenoide sept 2013 Cartographie magnetique nov 2013 B 0 [µT] X [cm] 33

Conclusions EDM at PSI: datataking started in 2012 Analysis: thesis Yoann Kermaidic n 2 EDM: 2 chambers to improve statistics and systematics Polarized 3 He: “ 3 years project” Thesis Mathieu Guigue 34

The n. EDM experiment at PSI BACKUP SLIDES 35

B 0 current source 36

Collisions with walls Exotic contribution Holding field External Collisions magnetic field inhomogeneities with dipoles inhomogeneities Fluxgate magnetomter 2010 experiment

Le magnétomètre mercure Le Comagnétomètre corrige les fluctuations du champ magnétique 39

Test de l’invariance de Lorentz Interaction potential Earth rotation axis A spin up (at ILL) Neutron spin precession Daily modulation Cosmic axial field b

Limite sur la modulation a 24 h April 2008, 5 days of data. December 2008, 6 days of data. 41 Altarev et al, Phys. Rev. Lett 103 (2009)

Ultracold neutrons (UCN) Thermal neutrons UCNs feel gravity Cold neutrons Ultracold neutrons Neutrons with energy < 100 ne. V, or velocity < 5 m/s are reflected by material walls GRANIT to measure the bouncing quantum states UCNs can be stored in bottles for very long times (1000 s) precision measurement of the neutron electric dipole moment (n. EDM) 42

Geometric phase of mercury Motional (transverse) field Magnetic transverse field Frequency shift correlated with electric field False EDM for Mercury (fast regime of GPE) Pendlebury et al, PRA 70 032102 (2004) False neutron EDM when using Hg comagnetometer Indirect systematic effect 43

Dedicated measurement with Hg magnetometer 1) Apply a large magnetic gradient with trimcoils 2) Apply an electric field of 100 k. V/12 cm, with polarity reversed every 20 cycles 3) Take data for 20 days with different gradient configurations A clear correlation between Hg frequency and the electric field in the presence of a magnetic gradient. 44

Dedicated measurement with Hg magnetometer Final result theory Magnetic gradient extracted from fluxgates maps 45

Impurities on the electrode Scan of the Sussex bottom electrode At PTB in Nov. 2011 Groove insulating ring Approximate dipole position We would then quote a systematic effect Approximate dipole strength 46

Transverse field measured with fluxgate maps 47