Towards an RF Wien-Filter for EDM Searches in Storage Rings

Transcription

1 Towards an RF Wien-Filter for EDM Searches in Storage Rings DPG Annual Spring Meeting 2015 Wuppertal, March 10, 2015 Sebastian Mey and Ralf Gebel for the JEDI Collaboration Forschungszentrum Jülich

2 Content EDM Measurements in Magnetic Storage Rings The RF ExB Dipole Measurements Conclusion Wuppertal, March 10, 2015 EDM Measurements in Magnetic Storage Rings 2

3 Spin Motion in a Magnetic Storage Ring Thomas-BMT Equation: d S = S ( Ω dt MDM + Ω EDM ) ( Ω MDM = q (1 + γg) B m + (1 + G) B ( ) ) γ + γ+1 γg β E/c ( ) Ω EDM = q η E/c m 2 + β B Standard Model: d = η q 2mc S ecm η Wuppertal, March 10, 2015 s.mey@fz-juelich.de EDM Measurements in Magnetic Storage Rings 3

4 Spin Motion in a Magnetic Storage Ring Thomas-BMT Equation: d S = S ( Ω dt MDM + Ω EDM ) ( Ω MDM = q (1 + γg) B m +(1 + G) B ( ) ) γ + γ+1 γg β E/c ( ) Ω EDM = q η E/c m 2 + β B Standard Model: d = η q 2mc S ecm η B main y spin precession around main dipole s guiding field spin tune ν S = γg! vertical polarization component S y is constant S Ω β z Wuppertal, March 10, 2015 s.mey@fz-juelich.de EDM Measurements in Magnetic Storage Rings 3

5 Spin Motion in a Magnetic Storage Ring Thomas-BMT Equation: d S = S ( Ω dt MDM + Ω EDM ) ( Ω MDM = q (1 + γg) B m +(1 + G) B ( ) ) γ + γ+1 γg β E/c ( ) Ω EDM = q η E/c+ m 2 β B Standard Model: d = η q 2mc S ecm η β B B motional electric field pointing to the ring s center tilts precession axis in case of non-vanishing EDM contribution oscillation of vertical spin component S y Wuppertal, March 10, 2015 s.mey@fz-juelich.de EDM Measurements in Magnetic Storage Rings 3 β Ω z y x

6 Generating an EDM Signal utilize beam with spins oriented in the horizontal plane modulate spin precession with vertical magnetic RF field in phase with the spin precession additional precession every turn frequency spectrum of spin precession picks up a zero component together with tilted precession axis this will cause a continuous build-up of vertical spin component! minimize beam disturbances by RF field utilize Wien-Filter configuration [ W. M. Morse, Y. F. Orlov and Y. K. Semertzidis, Phys. Rev. ST Accel. Beams 16, (2013)] Wuppertal, March 10, 2015 s.mey@fz-juelich.de EDM Measurements in Magnetic Storage Rings 4

7 Content EDM Measurements in Magnetic Storage Rings The RF ExB Dipole Measurements Conclusion Wuppertal, March 10, 2015 The RF ExB Dipole 5

8 The RF ExB Dipole in Wien-Filter Configuration RF B dipole RF E dipole ferrite blocks foil electrodes 50 µm stainless steel coil: 8 windings length 560 mm distance 54 mm length 580 mm ceramic beam chamber Parameters RF B dipole P RMS / W 90 Î / A 5 ˆBx dl / Tmm f RF range / khz Parameters RF E dipole P RMS / W 90 Û / kv 2 Êy dl / kv 24.1 f RF range / khz Wuppertal, March 10, 2015 s.mey@fz-juelich.de The RF ExB Dipole 6

9 The RF ExB Dipole in Wien-Filter Configuration RF B dipole RF E dipole ferrite blocks foil electrodes 50 µm stainless steel coil: 8 windings length mm distance 54 mm length 580 mm ceramic beam chamber Fy / ev/m ecβ ˆBx Wuppertal, March 10, 2015 s.mey@fz-juelich.de The RF ExB Dipole 6 x / m eê y z / m 100 ˆFy dz! 0 = 0 ev/m Fy / ev/m Fy / ev/m x / m z / m Fy / ev/m

10 COSY as Spin Physics R&D Facility RF solenoid RF ExB dipole εx,y and pp control beam cooling experiments with 970 MeV/c G = γ G = frev = 750 khz fs = 120 khz fast, continuous polarimetry polarized source Wuppertal, March 10, 2015 s.mey@fz-juelich.de The RF ExB Dipole 7

11 COSY as Spin Physics R&D Facility RF solenoid εx,y and pp control beam cooling RF ExB dipole experiments with 970 MeV/c G = γ G = frev = 750 khz fs = 120 khz fast, continuous polarimetry polarized source Wuppertal, March 10, 2015 frf = frev n γ G ; n Z n frf / khz s.mey@fz-juelich.de The RF ExB Dipole

12 Content EDM Measurements in Magnetic Storage Rings The RF ExB Dipole Measurements Conclusion Wuppertal, March 10, 2015 Measurements 8

13 Vertical Polarization Measurements beam polarization average over all particles spins massive carbon target with slow extraction long observation time polarization rate asymmetries in 12 C( d, d) : P y N left N right N left +N right Beam Target Wuppertal, March 10, 2015 s.mey@fz-juelich.de Measurements 9

14 Vertical Polarization Measurements beam polarization average over all particles spins massive carbon target with slow extraction long observation time polarization rate asymmetries in 12 C( d, d) : P y N left N right N left +N right RF ExB dipole: localized radial magnetic field tilt of Ω RF field in phase with spin precession accumulation of spin kicks continuous rotation of P oscillation of P y Target Beam Wuppertal, March 10, 2015 s.mey@fz-juelich.de Measurements 9 β z y Ω B x

15 Measurement Resonance Strength Run3577 fpy: Hz, τ: s Run3584 fpy: Hz, τ: s fpy = Hz at f RF = khz min CR y CR y fpy / Hz 0.4 χ 2 / ndf / 3 Curvature 1.73e+06 ± 9.91e+04 Minimum at ± 5.632e χ / ndf / 95 cos Offset ± cos Phase ± cos Freq / Hz ± χ / ndf / 95 cos Offset ± cos Phase ± 4.81 cos Freq / Hz ± Offset ± exp scale ± exp τ / s 6.64 ± t / s -0.3 exp scale ± exp τ / s ± t / s 0.3 CR y 0.3 Run3585 fpy: Hz, τ: s CR y 0.3 Run3574 fpy: Hz, τ: s χ / ndf / 95 cos Offset ± cos Phase ± 4.50 cos Freq / Hz ± exp scale ± exp τ / s 4.68 ± t / s χ / ndf / 95 cos Offset ± cos Phase ± 8.89 cos Freq / Hz ± exp scale ± exp τ / s ± t / s f RF =(1-Gγ)f / khz rev total spin flip only on resonance average polarization 0 minimum of vertical polarization oscillation frequency! measurement of resonance strength ε = f Py min f rev Wuppertal, March 10, 2015 s.mey@fz-juelich.de Measurements 10

16 Determination of Lorentz Force Compensation RF Wien-Filter at f RF = ( 1 + ν s )f rev = Hz RF Wien-Filter: f Py 1+G ˆB dl 4πγ Bρ ; RF-solenoid: f P y 1+G 4π RF-dipole: f Py 1+γG 4π ˆB dl Bρ ˆB dl Bρ + interference from beam oscillations (2-qy)frev / khz fpy / Hz preliminary data qy Wuppertal, March 10, 2015 s.mey@fz-juelich.de Measurements 11

17 Content EDM Measurements in Magnetic Storage Rings The RF ExB Dipole Measurements Conclusion Wuppertal, March 10, 2015 Conclusion 12

18 Conclusion versatile RF ExB dipole prototype minimal excitation of coherent beam oscillations has been successfully commissioned rotated version with vertical magnetic field scheduled for commissioning at the end of 2015 systematic studies for disentangeling possible EDM signals from imperfection background Tuesday, March 10, 18:00 (HS1) Artem Saleev: Systematic studies of spin dynamics in preparation for the EDM searches Thursday, March 12, 14:30 (HS 1) Fabian Hinder: Development of new Beam Position Monitors at COSY Wuppertal, March 10, 2015 Conclusion 13

19 Content EDM Measurements in Magnetic Storage Rings The RF ExB Dipole Measurements Conclusion Wuppertal, March 10, 2015 Spares 14

20 RF ExB Setup for Field Compensation Phase 30% Output Amplitude, Natural Beamloss (38.2±1.1)% move betatron sideband onto RF frequency for max. sensitivity polarimeter target directly above beam limits acceptance exited part of beam is removed diagnosis with COSY beam current transformer determination of amplitudes and phase corresponding to Lorentz force compensation down to per mille! fqy = khz, f = khz, Î RF-B = (232.6±0.6) ma, Û RF-E = (132.0±0.3) V rel. beam loss / % beam loss w. o. RF ExB 38.2 ± 1.1 % preliminary data Input φ(e-b) / Amplitude 30% Output Amplitude, Natural Beamloss (38.2±1.1)% rel. beam loss / % fqy = khz, f = khz, Î RF-B = (232.5±0.6) V, Input φ(e-b) = 90 beam loss w. o. RF ExB 38.2 ± 1.1 % preliminary data Û RF-E / V Wuppertal, March 10, 2015 s.mey@fz-juelich.de Spares 15

21 Thomas-BMT Equation in Case of an RF Wien-Filter consider device with pure radial magnetic and vertical electric field adjust net Lorentz force to zero E/c = β B from Thomas-BMT Equation: Ω = (1 + γg) B + (1 + G) B 0 ( ) = 1 β2 γ + γ+1 (1 β2 )γg B = 1+G γ B β E/c ( γ γ+1 + γg ) z β y E/c = β ( β B)=β 2 B {}}{ β E/c particles sample localized RF field once each turn at orbit angle θ b(θ) = ( ) ˆB dz cos f RF f rev θ + φ n= δ(θ 2πn) Wuppertal, March 10, 2015 s.mey@fz-juelich.de Spares 16 x B

22 Resonance Strength of an RF Wien-Filter intrinsic resonance strength given by spin rotation by turn, calculate Fourier integral over driving fields along orbit : ɛ K = f spin = 1+G 2πγ = 1+G 2 2πγ f rev = 1+G b(θ) 2πγ Bρ eik θ dθ ˆB dz Bρ n= cos(2πn f RF f rev ˆB dz Bρ n e±iφ δ(n K f RF f rev ) + φ)e i2πkn spin tune γg, resonance at every sideband with K =! γg = n ± f RF f rev f RF = f rev n γg ; n Z d at 970 MeV/c: f rev = khz; γg = n f RF / khz [* S. Y. Lee, /PhysRevSTAB (2006)] Wuppertal, March 10, 2015 s.mey@fz-juelich.de Spares 17