nEDM-2014, 2-6 November Crystal diffraction nEDM experiment. Present status Voronin Vladimir PNPI, Gatchina, Russia

Outline The method idea Test experiments Full scale setup with quart crystal Possibility to improve Summary nEDM-2014, 2-6 November

nEDM-2014, 2-6 November Neutron EDM Non zero EDM means the P and T violation P P – spatial inversion С С – particle – antiparticle inversion Т Т – time inversion CPT theorem (Lüders (1954); Pauli(1955)) (Our world is СРТ invariant) Non zero nEDM means СР violation

nEDM-2014, 2-6 November History of nEDM experiment Standard model d n ~( ) e cm New physics to explain the baryon asymmetry (experiment - n b /n  ~ SM - n b /n  ~ ) d n ~( ) e cm Neutron scattering in-flight magnetic resonance UCN magnetic resonance

nEDM-2014, 2-6 November Idea nEDM experiment 2(E·D) -E +EDD Interaction time with Е Sensitivity to nEDM Neutron size R n ~ cm, d n /R n ~ 3  Corresponding size from Earth is ~ 2 μm Current accuracy to d n

nEDM-2014, 2-6 November Sensitivity to neutron EDM E~ grad V e ~(0.1-1)GV/cm UCN method Crystal-diffraction method E ~ a few 10 kV/cm τ ~ 1000s (time of life) Е τ ~ 10 7 (V·s)/cm Е τ Now Е τ ≈ 10 6 (V·s)/cm τ a ~ 0.01 c (absorption) 10 7 (V·s)/cm ЕτЕτЕτЕτ Electron bonding energy ~ a few eV Å

Potential of neutron interaction with crystal For nonabsorbing potential V(r), i.e. Amplitude and phase of g-harmonics g=2 π/d nEDM-2014, 2-6 November

Neutron wave function in crystal - neutron wave vector in crystal nEDM-2014, 2-6 November

Neutron energy in crystal For the case of non- centrosymmetric crystal Neutron energy in crystal depends on the spin direction near the Bragg reflex nEDM-2014, 2-6 November

nEDM-2014, 2-6 November  /2 Idea of the experiment For  /2 reflection E || v n and H s ~[E x v n ]≈0+E-E

nEDM-2014, 2-6 November Electric field quartz (110) plane L c =14 cm Bragg angle ≈ · 10 8 V/cm Theory + 0.8·10 8 V/cm Variation of the  T on  1K E ≈  10 8 V/cm

nEDM-2014, 2-6 November π/2 reflection “zero” [v x E] For  /2 reflection E || v n and H s ~[E x v n ]≈0 g vv V || +E -E

Scheme of the experiment nEDM-2014, 2-6 November 2014 H≈0 T=T 0 T=T 0 +ΔT

3-D polarization analyzes Magnetic field || surface of the superconductor. H L ≈0H L ≠0 P Current accuracy of spin orientation is ~10 -2 rad ~10 -2 rad for routine experiment ~10 -3 rad ~10 -3 rad can be reached for special cases F. Tasset, P.J. Brown, E. Lelie`vre-Berna, T. Roberts, S. Pujol, J. Allibon, E. Bourgeat-Lami, Physica B, (1999) nEDM-2014, 2-6 November 2014

15 Matrix of spin rotation H s ~[E x v n ]  E||Z EDM and [v x E] effects give an orthogonal matrix elements EDM[v x E]Residual magnetic field H e =(E d n )/  n 3D spin analysis allows to separate the EDM and [v x E] effect. PiPi PfPf M+M+ M-M- X Y Z

nEDM-2014, 2-6 November Spatial distribution of [v x E] PiPi PfPf M+M+ M-M- X Y Z  P=P(  T + )-P(  T - ) We should observe the same dependence for Pxy and Pyx components responsible for nEDM

nEDM-2014, 2-6 November nEDM spatial distribution We don’t see the spatial dependence of Pxy and Pyx components responsible for nEDM. [v x E]  P s < stat. accuracy is  P~

nEDM-2014, 2-6 November nEDM test experiment (PNPI-ILL) 1.Field value coincide with the theory E= (0.7±0.1) 10 8 V/cm for (110) quartz plane 2.The statistical sensitivity was ~ e cm/day. 3.The sensitivity can be improved by a factor of 65 and reach about e cm/day for the full scale experiment, mainly by increasing the divergence acceptance of the installation, the beam size, and the crystal length.

nEDM-2014, 2-6 November Residual magnetic field Value Time stability Accuracy of polarization 3D analysis Angular crystals alignment Precision of temperature control Δd/d < ~0.01 arc degree Flatness windows of CRYOPAD Interplanar space variation ~0.01 K Summary of systematics to reach the e cm Summary of systematics to reach the σ d ~ e cm

Full scale setup is now under construction nEDM-2014, 2-6 November 2014

nEDM-2014, 2-6 November 2014 Quartz crystal test. Main idea Backscattering geometry Sample Reference crystal Bragg width of neutron reflex in  d/d is ~

nEDM-2014, 2-6 November Quartz crystal test

Y Z X 105х100х500 mm 3 Summary crystal size is 105х100х500 mm 3 (15 item with 35х100х100 mm 3 ) Interplanar space dispersion is  d/d=  2   d/d=  2  over the all crystal Quartz crystal nEDM-2014, 2-6 November

The CRYOPAD-EDM parameters: 600 mm Inner size for crystal is 600 mm. 100х100 mm 2 Size of the windows for neutron beam 100х100 mm rad The entrance and outgoing windows should be parallel with accuracy rad рад Homogeneity of magnetic field over the windows should be about рад. CRYOPAD-EDM nEDM-2014, 2-6 November 2014

CRYOPAD-EDM (ILL design) General view Inner coil for longitudinal polarization analysis ~ Homogeneity of the field is ~ nEDM-2014, 2-6 November 2014

Input and output nutators It was found a geometry of the nutators allowing to get a misalignment of the field on the Meissner screens which will be of the order of ± on the whole section of the beam (100 x 100 mm 2 ) nEDM-2014, 2-6 November 2014

nEDM-2014, 2-6 November Sensitivity for the quartz crystal For the 100x100x500 mm 3 (110) plane it can be е см per 100 day How to improve this sensitivity?

nEDM-2014, 2-6 November New non-centrosymmetric crystal request Low neutron absorption No center of symmetry Elements with large Z  d/d < Bragg width (~10 -5 Perfect crystal (  d/d < Bragg width (~10 -5 ))

nEDM-2014, 2-6 November CrystalSymmetry group hkld, (Å)E g, 10 8 V/cm  a, ms E g  a, (kV  s/cm)  -quartz (SiO 2 ) 32(D 6 3 ) Bi 12 SiO 20 I Bi 12 GeO 20 I PbOP c a BeO6mm Parameters of some NCS crystals

nEDM-2014, 2-6 November Storage variant t=0 0<t<2t a t=2t a 3 He cell Detector HfHf HiHi Perfect crystal reflection T=T 0 T=T 0  T Up to 1000 reflections (  s ~1 s) M.R. Jaekel, C.J. Carlile, E.Jericha, D.E. Schwab and H. Rauch, SPIE Vol EUV, X-Ray, and Neutron Opticas and Sources, 353 (2000)

nEDM-2014, 2-6 November Some numerical estimation Bragg width – Responsible time – Crystal acceleration – (fast piezoelectric element?)

nEDM-2014, 2-6 November Sensitivity estimation for Sensitivity estimation for Bi 12 SiO 20 (444) E g, 10 8 V/cm , ms Count rate K inp  d, e  cm per day  -quartz (110) in-flight (L=50cm) 10 4 n/s (ILL PF1) (2-3) Bi 12 SiO 20 (444) storage (L=15 cm) 10 3 n/s (ESS) 10 (2-3)10 -26

nEDM-2014, 2-6 November Conclusion  d ~(2-3)· e·cm per 100 day Full scale setup with quartz crystal are now under construction. Expected sensitivity is  d ~(2-3)· e·cm per 100 day Storage modification of crystal-diffraction nEDM experiment can reach a sensitivity  d ~(2-3)· e·cm  d ~(2-3)· e·cm for the European Spallation Source and BSO crystal