11.09.2018 I Alexander Nass for the JEDI collaboration Commissioning of the RF Wien filter for a first deuteron EDM measurement at COSY/Jülich 11.09.2018 I Alexander Nass for the JEDI collaboration

Proof of principle experiment at COSY: („precursor experiment“) Highest EDM sensitivity shall be achieved with a new type of machine: An electrostatic storage ring, where: Centripetal force produced primarily by electric fields Electric field couples to EDM and provides required sensitivity (< 1028 e cm) In this environment, magnetic fields mean evil (since 𝜇 is large) Idea behind proof of principle experiment with novel RF Wien filter ( 𝐸 × 𝐵 ): In magnetic machine, particle spins (protons, deuterons) precess about stable spin axis (≅ direction of magnetic fields in dipole magnets) Use RF device operating on some harmonic of the spin precession frequency: Phase lock between spin precession and device RF Allows to accumulate EDM effect as functionof time in cycle (~ 1000 s) Show that conventional storage ring usable for first direct EDM measurement 11. September 2018

Model calculation of EDM build-up with RF Wien filter Ideal ring with deuterons at 𝑝 𝑑 =970 MeV/c: 𝐺=−0.143, 𝛾=1.126, 𝑓 𝑆 = 𝑓 𝑟𝑒𝑣 𝛾𝐺+ 𝐾 =0 ≈120.765 kHz Electric RF field integral assumed 1000 × 𝐸 𝑊𝐹 ∙𝑑𝑙 ≈2200 kV (w/o ferrites) EDM accumulates in 𝑃 𝑦 (𝑡)∝ 𝑑 EDM 11. September 2018

The RF Wien filter Waveguide design provides 𝐸 × 𝐵 by design. Support for geodetics Inner support tube Support structure for electrodes RF feedthrough Ferrit cage BPM (Rogowski coil) Beam pipe (CF 100) Copper electrodes Ferrit cage Mechanical support Vacuum vessel with small angle rotator Belt drive for 90 0 rotation Aim was to build the best possible device with respect to electromagnetic performance, mechanical tolerances, etc. Device rotatable by 90 0 in situ Clamps for the Ferrit cage ~1 m 11. September 2018

Electromagnetic field simulations Full-wave simulation with CST Microwave Studio Each simulation required ~12 hours of computing time Excellent cooperation with RWTH Aachen and ZEA / FZ Jülich 11. September 2018

Driving Circuit Realization with load resistor and tunable elements Maximum 4 × 1 kW power available Adjustment of phase and relative amplitudes of E and B field Different 𝐿𝑓 permit the use in the frequency range of 0.6−1.7 MHz Current / voltage detectors 𝑈,𝐼 𝑖=1…9 used to monitor the system Driving circuit used to power system and match it for zero Lorentz force 11. September 2018

Phase and impedance matching Measured phase and impedance for 𝑓 WF =871 kHz 𝐸/𝐵 phase as function of 𝐶L and 𝐶T Impedance 𝑍9 as function of 𝐶L and 𝐶T 𝑍 9 =79 Ω when matched to deuteron momentum of 970 MeV/c 11. September 2018

Control System Control via LABVIEW. Feedback loops keep the system in optimal working condition. EPICS used to exchange data. 11. September 2018

Installation into COSY Installed at COSY since April 2017. 11. September 2018

Lorentz force measurements COSY BPMs measure beam position Unmatched RF Wien filter excites beam at 𝑓 WF Lock-In amplifiers are used to extract excitation from BPM signal Signal is sent to EPICS RF Wien filter is matched by minimizing the beam excitation 11. September 2018

Lorentz force measurements Dependence on beam size and shape: Normal COSY lattice Matching point at 𝐶L = 6800 and 𝐶T = 4950, where in addition phase between 𝐸 and 𝐵 field is zero. 11. September 2018

Lorentz force measurements Dependence on beam size and shape: COSY lattice with low-𝛽 section on Same matching point at 𝐶L = 6800 and 𝐶T = 4950. Excitations in unmatched case larger. 11. September 2018

Lorentz force measurements Dependence on RF Wien filter frequency 629.4 kHz 871 kHz Different matching points. Tuning with loop 2 and 3. 1379.6 kHz 1621.2 kHz 11. September 2018

Driven oscillations Matched RF Wien filter in 90° position (radial B field): Polarization is rotated in 𝑥𝑦 plane. 11. September 2018

COSY cycle for resonant build-up measurements: RF Wien filter in 0° position (vertical 𝐵 field) Beam preparation (injection, acceleration, bunching, cooling) Switch off cooler, including toroid magnets Rotation of spin into horizontal plane (RF solenoid) Start spin tune feedback set relative phase between RF-WF and spin precession Switch on Siberian Snake Power up RF Wien filter Measure build-up 𝑃 𝑦 (𝑡) 11. September 2018

Resonant build-up Rate of out-of-plane rotation angle 𝛼 as function of RF-WF phase. Variation of the RF Wien filter rotation angle, Siberian snake off. 11. September 2018

Resonant build-up Rate of out-of-plane rotation angle 𝛼 as function of RF-WF phase. Variation of the spin angle by Siberian snake. RF Wien filter at 0°. 11. September 2018

Expectation for 𝑑= 10 −20 e cm in ideal COSY ring Resonant build-up Expectation for 𝑑= 10 −20 e cm in ideal COSY ring 11. September 2018

Expectation for 𝑑= 10 −18 e cm in ideal COSY ring Resonant build-up Expectation for 𝑑= 10 −18 e cm in ideal COSY ring 11. September 2018

Resonant build-up: Data from COSY 𝑑= 10 −20 e cm, ideal COSY ring 𝟏𝟔 data points from last run In upcoming run, produce map covering minimum 11. September 2018

Summary RF Wien filter method together with spin tracking simulation is a powerful tool to: Rotate spin in 𝑥𝑦 plane (in 90° mode) Measure resonant EDM build-up of vertical polarization Conduct a first EDM measurement with deuterons Study imperfections of accelerator Next steps: Improve beam position monitors around RF Wien filter Improvements to Siberian snake First EDM measurement with deuterons (Nov./Dec. 2018) 11. September 2018