Spin Manipulation with an RF Wien-Filter at COSY PSTP Workshop 2015

Transcription

1 Spin Manipulation with an RF Wien-Filter at COSY PSTP Workshop 2015 Bochum, September 15, 2015 Forschungszentrum Jülich Sebastian Mey and Ralf Gebel for the JEDI Collaboration

2 Content EDM Measurements in Magnetic Storage Rings The Prototype RF ExB-Dipole Measurements Summary and Conclusion Bochum, September 15, 2015 EDM Measurements in Magnetic Storage Rings 2

3 Motivation JEDI Collaboration: First direct measurement of charged light hadrons permanent Electric Dipole Moment in storage rings simple system with EDM d and MDM µ aligned with spin S H = µ S S B d S S E P(H) = µ S S B + d S S E T (H) = µ S S B + d S S E EDMs violate tests both parity P and time reversal T symmetry CPT Theorem: permanent EDMs violate CP symmetry source: en.wikipedia.org Bochum, September 15, 2015 s.mey@fz-juelich.de EDM Measurements in Magnetic Storage Rings 3

4 Spin Motion in a Magnetic Storage Ring JEDI Collaboration: First direct measurement of charged light hadrons permanent EDM in storage rings spin motion: d S = S ( Ω dt MDM + Ω EDM ) (Thomas-BMT Equation) ( 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 MDM: µ = 2(G + 1) q 2m S with anomalous magnetic moment G EDM: d = η q 2mc S ecm η for SM light hadrons Bochum, September 15, 2015 s.mey@fz-juelich.de EDM Measurements in Magnetic Storage Rings 4

5 Spin Motion in a Magnetic Storage Ring JEDI Collaboration: First direct measurement of charged light hadrons permanent EDM in storage rings spin motion: d S dt = S ( Ω MDM + Ω EDM ) (Thomas-BMT Equation) stationary ring with vertical guiding field B and B = E = 0 ( 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 couples to motional electric field MDM: µ = 2(G + 1) q 2m S with anomalous magnetic moment G EDM: d = η q 2mc S ecm η for SM light hadrons Bochum, September 15, 2015 s.mey@fz-juelich.de EDM Measurements in Magnetic Storage Rings 4

6 Generating an EDM Signal stationary ring with vertical guiding field B and B = E = 0 ( Ω ring = q (1 + γg) B + η β ) η B m 2 2β B γgb spin precession around vertical axis with tune γg Ω ring tiny EDM tilt of precession axis prepare beam with purely horizontal spins oscillating vertical spin component, but signal mutch too small to observe Bochum, September 15, 2015 s.mey@fz-juelich.de EDM Measurements in Magnetic Storage Rings 5 β z y x

7 Generating an EDM Signal stationary ring with vertical guiding field B and B = E = 0 ( Ω ring = q (1 + γg) B + η β ) η B 2β B m 2 γgb spin precession around vertical axis with tune γg Ω ring tiny EDM tilt of precession axis y prepare beam with purely horizontal spins S oscillating vertical spin component β x z introduce additional in-plane spin kick in phase with precession oscillating spins point forward most of the time continuous build-up of vertical spin component EDM Signal Bochum, September 15, 2015 s.mey@fz-juelich.de EDM Measurements in Magnetic Storage Rings 5

8 Generating an EDM Signal, cont. B WF supplement lattice with local vertical magnetic field B WF oscillating with spin precession minimize beam perturbation by adjusting net Lorentz Force to zero β B WF E WF /c = β B z WF (Wien-Filter condition) β additional spin rotation in RF Wien-Filter around vertical axis ( Ω MDM = q (1 + γg) ( ) ) B m WF γ + γ+1 γg β EWF /c Ω EDM = q m η 2 ( EWF /c + β B ) WF = 0 y E WF /c Bochum, September 15, 2015 s.mey@fz-juelich.de EDM Measurements in Magnetic Storage Rings 6 x

9 Generating an EDM Signal, cont. B WF supplement lattice with local vertical magnetic field B WF oscillating with spin precession minimize beam perturbation by adjusting net Lorentz Force to zero E WF /c = β B WF (Wien-Filter condition) β additional spin rotation in RF Wien-Filter around vertical axis Ω MDM = = q B m WF 1+G γ β B WF z y E WF /c The RF Wien-Fielter itself is EDM transparent, but is capable of generating an EDM signal due to modulation of the spin precession.* [ W. M. Morse, Y. F. Orlov and Y. K. Semertzidis, Phys. Rev. ST Accel. Beams 16, (2013)] Bochum, September 15, 2015 s.mey@fz-juelich.de EDM Measurements in Magnetic Storage Rings 6 x

10 Content EDM Measurements in Magnetic Storage Rings The Prototype RF ExB-Dipole Measurements Summary and Conclusion Bochum, September 15, 2015 The Prototype RF ExB-Dipole 7

11 Prototype RF Wien-Filter with Radial Magnetic Field investigate action of RF Wien-Filter fields by direct observation of resulting MDM motion use radial magnetic field with vertically prepared spins continuous rotation of spin vector during operation β E/c z β y E/c x B Lorentz force compensation: E/c = β B spin precession: ΩMDM = 1+G γ B 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) Bochum, September 15, 2015 s.mey@fz-juelich.de The Prototype RF ExB-Dipole 8

12 Resonance Strength of an RF Wien-Filter intrinsic resonance strength given by spin rotation per 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)] Bochum, September 15, 2015 s.mey@fz-juelich.de The Prototype RF ExB-Dipole 9

13 The Prototype RF ExB Dipole coil: 8 windings length 560 mm distance 54 mm length 580 mm Parameters RF B dipole P RMS / W 90 Î / A 5 ˆBx dl / Tmm f RF range / khz Pa P f RF Bochum, September 15, 2015 s.mey@fz-juelich.de The Prototype RF ExB-Dipole 10

14 The Prototype RF ExB Dipole coil: 8 windings length mm distance 54 mm length 580 mm Fy / ev/m eê y 100 ˆFy dz! 0 = 0 ev/m Fy / ev/m Fy / ev/m x / m ecβ ˆBx z / m x / m Bochum, September 15, 2015 s.mey@fz-juelich.de The Prototype RF ExB-Dipole 10

15 Content EDM Measurements in Magnetic Storage Rings The Prototype RF ExB-Dipole Measurements Summary and Conclusion Bochum, September 15, 2015 Measurements 11

16 COSY as Spin Physics R&D Facility RF solenoid RF ExB dipole εx,y and pp control electron cooling fast, continuous polarimetry polarized source Bochum, September 15, 2015 Measurements 12

17 COSY as Spin Physics R&D Facility RF solenoid RF ExB dipole fast, continuous polarimetry polarized source Bochum, September 15, 2015 all events P bunch-shape evolution per fill time in cycle / s Measurements left, right up, down position along ring / m εx,y and pp control electron cooling 12

18 RF ExB Setup for Field Compensation Amplitude Scan RF-E at Î RF-B = 2 A 80.0 move betatron sideband onto RF freq. for max. sensitivity q y f rev! = (1+γG)f rev = 629 khz polarimeter target directly above beam limits acceptance exited part of beam is removed diagnosis with COSY beam current transformer over t = 30 s determination of amplitudes and phase corresponding to Lorentz force compensation down to per mille! rel. beam loss / % Û RF-E / V Input φ(e-b) / Bochum, September 15, 2015 s.mey@fz-juelich.de Measurements 13 rel. beam loss / % Phase Scan

19 Beam Response Analogue signal from one vertical BPM pickup electrode during RF operation exactly on resonance Center f qy = f rev (1 + q y ) = 1380 khz, Span f = 10 khz t/s t = 30 s t/s t = 30 s f /Hz RF Wien-Filter: Î RF-B 740 ma; Û RF-E 108 V RF Sol.: Î Sol. 780 mapp f /Hz Bochum, September 15, 2015 s.mey@fz-juelich.de Measurements 14

20 Polarization Measurements beam polarization average over all particles spins massive carbon target with slow extraction long observation time polarization signal rate asymmetries in 12 C( d, d) : P y N left N right N left +N right continuous rotation of P oscillation of P y Beam Target Bochum, September 15, 2015 s.mey@fz-juelich.de Measurements 15

21 Measurement Resonance Strength CR LR f / Hz Run 3449: Vertical Polarization Amplitude ± Damping Time ± Frequency ± δ Frequency 5.777e-09 ± 7.468e-02 Phase ± Offset ± t / s Vertical Polarization Oscillation Frequency t / s Final CR LR Fitted f Py Fitted δf Py FFT f Py = ± = ( ± ) Hz = ( ± ) Hz = ( ± ) Hz Projection 2 Height ± Center ± Width ± Amp. total spin flip only on resonance average polarization 0 minimum of oscillation frequency f Py measurement of resonance strength ε = f Py min f rev / Hz f Py RF Wien-Filter and RF Solenoid both drive continuous rotation of P find resonance by scan of driving frequency f RF! = f rev (1 γg) Q y = 3.877: f = (0.210 ± 0.001) Hz Py min χ 2 / ndf / 2 Factor ± Minimum 8.714e+05 ± Offset ± f rev (1-γ G) / Hz Bochum, September 15, 2015 s.mey@fz-juelich.de Measurements 16

22 Preliminary result of Fixed Frequency Scans resonance strength measurements to determine level of field compensation RF Solenoid: f Py = q 1+G p 4π ˆBd l RF Wien-Filter: fpy = q 1+G p 4πγ ˆBd l RF B-Dipole: f Py = q 1+γG p 4π ˆBd l + interference due to beam motion RF E-Dipole: f Py = q 1/γ+1+G mc 2 4π Êd l + interference due to beam motion Bochum, September 15, 2015 s.mey@fz-juelich.de Measurements 17

23 Content EDM Measurements in Magnetic Storage Rings The Prototype RF ExB-Dipole Measurements Summary and Conclusion Bochum, September 15, 2015 Summary and Conclusion 18

24 Summary versatile prototype RF ExB dipole with minimal excitation of coherent beam oscillations has been successfully commissioned P RMS = 90 W ˆBx dl = T mm; Ê y dl = 24.1 kv Frequency Range 630 khz khz entirely beam-based method for field matching has been worked out and verified spin manipulation performance on the same level as with the proven RF-Solenoid system Bochum, September 15, 2015 s.mey@fz-juelich.de Summary and Conclusion 19

25 Outlook first attempt of a direct measurement of the deuteron EDM requires a upright, high precision version of an RF Wien-Filter rotatable stripline solution scheduled for commissioning at COSY in summer 2016 introduction of the concept and field simulations J. Slim, Towards a High-Accuracy RF Wien Filter for Spin Manipulation at COSY Jülich Bochum, September 15, 2015 s.mey@fz-juelich.de Summary and Conclusion 20

26 Content EDM Measurements in Magnetic Storage Rings The Prototype RF ExB-Dipole Measurements Summary and Conclusion Bochum, September 15, 2015 Spares 21