Mitglied der Helmholtz-Gemeinschaft Search for Permanent Electric Dipole Moments at COSY Step 1: Spin coherence and systematic error studies (Proposal 216.1) February 24, 2014 Frank Rathmann on behalf of JEDI 42 nd Meeting of the COSY Programm Advisory Committee

Introduction Present proposal merges activities from #176 and #216 under the flag of JEDI. Aim: Use expertise of both groups to develop instrumentation and techniques for EDM searches at storage rings. for Permanent Electric Dipole Moments at COSY2

Outline 3Search for Permanent Electric Dipole Moments at

A 1: Spin coherence time for Permanent Electric Dipole Moments at COSY4

A 2: Spin tune determination for Permanent Electric Dipole Moments at COSY5 Understand implications for future precision experiments.

for Permanent Electric Dipole Moments at COSY6 Spin coherence time (s) 235 MeV Beam energy (MeV) Theory: N.N.Nikolaev

1. Spin coherence time studies (contin. of #176) Removing spin tune spread with sextupole fields: Observe result in lifetime (SCT) of horizontal polarization Major run in weeks 35 and 36 (August/September) 2013 (lots of data) for Permanent Electric Dipole Moments at COSY7 Example of data measured with the time-marking DAQ system HORIZONTAL POLARIZATION SCT signs changed to show linear effect black = spin down blue = spin up Zero crossing of inverse slope locates best SCT. Initial Polarization Slope

for Permanent Electric Dipole Moments at COSY8 MXG MXS Best SCT points for large horizontal emittance + Best SCT points for large Δp/p (longitudinal) Units: percent of power supply full scale. ξ X = 0 ξ Y = 0 Location of best SCT is closely associated with location of vanishing chromaticity. Each sextupole field scan locates one point on 2D map Beam set up to emphasize different sources of decoherence, which can be corrected with sextupole fields.

Chromaticity studies (tests in week 7) for Permanent Electric Dipole Moments at COSY9

Measurement of chromaticity Two methods for beam energy shift applied 1.Variation of electron cooler voltage 2.Variation of cavity frequency Tune measurement: Sweep frequency for beam excitation and measure response to locate betratron frequency Measure revolution frequency using Schottky spectrum Horizontal Vertical for Permanent Electric Dipole Moments at COSY10

Chromaticity: Arc sextupoles Three families in the arcs: (MXS, MXL, MXG) Non-vanishing dispersion in the arcs, large influence of chromaticity expected for Permanent Electric Dipole Moments at COSY11

Chromaticity: Straight section sextupoles Test of combined familiy of four straight section sextupoles (MXT: ) Dispersion minimized in straights, no impact on chromaticity expected for Permanent Electric Dipole Moments at COSY12 Straight section sextupoles show no effect on chromaticity

for Permanent Electric Dipole Moments at COSY13 Spin coherence time studies: Required time 2 weeks are requested to further explore ways to improve the SCT.

for Permanent Electric Dipole Moments at COSY14 Precursor EDM concept: Use RF Wien filter to accumulate EDM signal

for Permanent Electric Dipole Moments at COSY15

for Permanent Electric Dipole Moments at COSY16 Beam loss (%)

Systematic study of machine imperfections using two straight section solenoids for Permanent Electric Dipole Moments at COSY17

for Permanent Electric Dipole Moments at COSY18 Ideal machine with vanishing static imperfections: Saddle point at the origin

Beam Request for Permanent Electric Dipole Moments at COSY19

Backup slides for Permanent Electric Dipole Moments at COSY20

for Permanent Electric Dipole Moments at COSY21 Precursor experiments: RF methods Use existing magnetic machines for first direct EDM measurements Method based on making spin precession in machine resonant with orbit motion Two ways: 1.Use an RF device that operates on some harmonics of the spin precession frequency 2.Operate ring on an imperfection resonance

for Permanent Electric Dipole Moments at COSY22 Precursor experiments: 1. Resonance Method with „magic“ RF Wien filter Avoids coherent betatron oscillations of beam. Radial RF-E and vertical RF-B fields to observe spin rotation due to EDM. Approach pursued for a first direct measurement at COSY. Observable: Accumulation of vertical polarization during spin coherence time Polarimeter (dp elastic) stored d RF E(B)-field In-plane polarization

for Permanent Electric Dipole Moments at COSY23 Precursor experiments: 1. Resonance Method for deuterons at COSY

1. Resonance Method Operation of „magic“ RF Wien filter for Permanent Electric Dipole Moments at COSY24 Spin coherence time may depend on excitation and on harmonics.

for Permanent Electric Dipole Moments at COSY25 Precursor experiments: 1. Resonance Method for deuterons at COSY

Development: RF E/B-Flipper (RF Wien Filter) for Permanent Electric Dipole Moments at COSY26 Work by S. Mey, R. Gebel (Jülich) J. Slim, D. Hölscher (IHF RWTH Aachen)

for Permanent Electric Dipole Moments at COSY27 Precursor experiments: 2. Resonant EDM measurement with static Wien Filter Similar accumulation of EDM signal, systematics more difficult, strength of imperfection resonance must be suppressed by closed-orbit corrections. Spin rotation in phase with orbit motion without static WF

1Make the lines of zero chromaticity coincide. Recent machine development studies provide the slopes for chromaticity vs. MXL (not tried before). A negative MXL setting should pull the zero chromaticity lines toward each other. A “best case” chromaticity setup might work, as before. ξ X,Y = 0 2Explore straight section sextupoles (no effect on chromaticity) Sensitivity of SCT seen before (but weaker). Does different degree of freedom help? Based on analysis now underway, additional information would be useful: 3Revisit RF-solenoid-induced P Y oscillations at low field. Present analysis hampered by differential extraction on ridge target. 4Explore contribution of emittance in white noise extraction to SCT. for Permanent Electric Dipole Moments at COSY28

Removing spin tune spread with sextupole fields Observe result in lifetime (SCT) of horizontal polarization Major run in weeks 35 and 36 (August/September) 2013, lots of data MXG MXS Best SCT points for large horizontal emittance Best SCT points for large Δp/p (longitudinal) Units are in percent of power supply full scale. Example of data measured with the time-marking DAQ system HORIZONTAL POLARIZATION signs changed to show linear effect black = spin down blue = spin up Beam set up to emphasize different sources of decoherence, which can be corrected with sextupole fields. Each sextupole field scan locates one point on 2-D map. Zero crossing of inverse slope locates best SCT. SCT FIRST 2-D MAP Initial Polarization Slope for Permanent Electric Dipole Moments at COSY29

MXG MXS Best SCT points for large horizontal emittance Best SCT points for large Δp/p (longitudinal) Units are in percent of power supply full scale. ξ X = 0 ξ Y = 0 Location of best SCT is closely associated with location of vanishing chromaticity. Results comparable to calculated slopes for best SCT (X, Y emittance, and longitudinal Δp/p) and zero chromaticity. Slopes scaled to percent units. Offsets are arbitrary. Chromaticity effects are planar. Sextupoles adjust constant term. COSY-Infinity calculations by Marcel Rosenthal best fit to chromaticity data for Permanent Electric Dipole Moments at COSY30

Stability  5 days/nights of measurement Measurements using cavity (method 2) 2% shift of +0.3 expected 2% shift of expected for Permanent Electric Dipole Moments at COSY31

Machine History  Super Cycle: 1. cycle: no injection, dipole ramped to larger target momenta for 4- 5 seconds 2. cycle: usual measurement cycle time B-Field of bending dipoles measurement Additíonal dipole ramp Target momenta of additional ramp: 1: 2028 MeV/c 2: 2513 MeV/c 3: 3097 MeV/c 4: 3700 MeV/c 5: cycle 1 removed (default target momentum: 970 MeV/c) decreasing restoring increasing restoring for Permanent Electric Dipole Moments at COSY32

Do particles (e.g., electron, nucleon) have an EDM? for Permanent Electric Dipole Moments at COSY33 Physics: Fundamental Particles

Physics: Symmetries Parity: for Permanent Electric Dipole Moments at COSY34 C-parity (or Charge parity): Changes sign of all quantized charges electrical charge, baryon number, lepton number, flavor charges, Isospin (3rd-component) T-Symmetry: Physical laws are invariant under certain transformations

for Permanent Electric Dipole Moments at COSY Permanent EDMs violate P and T. Assuming CPT to hold, CP violated also. Not Charge symmetric EDMs: Discrete Symmetries

J.M. Pendlebury: „nEDM has killed more theories than any other single expt.“ for Permanent Electric Dipole Moments at COSY36 Physics: Potential of EDMs

for Permanent Electric Dipole Moments at COSY For transverse electric and magnetic fields in a ring ( ), anomalous spin precession is described by Thomas-BMT equation: x (magic) Principle: Frozen spin Method  Magic rings to measure EDMs of free charge particles

2 beams simultaneously rotating in an all electric ring (cw, ccw) Status: Approved BNL-Proposal Submitted to DOE Interest FNAL! Goal for protons for Permanent Electric Dipole Moments at COSY Beat systematics: BNL Proposal CW & CCW beams cancels systematic effects Many technological challenges need to be met

for Permanent Electric Dipole Moments at COSY39 srEDM searches: Technogical challenges These issues must be addressed experimentally at existing facilities

40Search for Permanent Electric Dipole Moments at Challenge: Electric field for magic rings Challenge to produce large electric field gradients

for Permanent Electric Dipole Moments at COSY41 Challenge: Niobium electrodes Show one slide on JLAB data HV devices DPP stainless steel fine-grain Nb large-grain Nb single-crystal Nb Large-grain Nb at plate separation of a few cm yields ~20 MV/m

for Permanent Electric Dipole Moments at COSY42 Challenge: Electric field for magic rings L~2.5 m Need to develop new electrode materials and surface treatments ~July 2013: Transfer of separator unit plus equipment from FNAL to Jülich

A one particle with magnetic moment “spin tune” “spin closed orbit vector” ring makes one turn stable polarization if ║ for Permanent Electric Dipole Moments at COSY Challenge: Spin coherence time Spin closed orbit

Challenge: Spin coherence time for Permanent Electric Dipole Moments at COSY44 At injection all spin vectors aligned (coherent) After some time, spin vectors get out of phase and fully populate the cone Polarization not affected! At injection all spin vectors alignedLater, spin vectors are out of phase in the horizontal plane Longitudinal polarization vanishes! In an EDM machine with frozen spin, observation time is limited.

Challenge: SCT stimates (N.N. Nikolaev) for Permanent Electric Dipole Moments at COSY45 One source of spin coherence are random variations of the spin tune due to the momentum spread in the beam andis randomized by e.g., electron cooling Estimate: Spin coherence time for deuterons may be × larger than for protons

EDM at COSY: COoler SYnchrotron Injector cyclotron COSY … the spin-physics machine for hadron physics for Permanent Electric Dipole Moments at COSY … an ideal starting point for a srEDM search

New Idea: Ivan Koop‘s spin wheel for Permanent Electric Dipole Moments at COSY47 B

How Ivan‘s spin wheel would work? for Permanent Electric Dipole Moments at COSY48 Frequency B field Find the value of B where spin precession frequency disappears

SQUIDs: Precision tools for accelerators for Permanent Electric Dipole Moments at COSY49 Possible applications in accelerators, all of which are needed for srEDM experiments 1.Beam current transformers 2.Beam position monitors 3.Beam polarimeters Begin development with a measurement of the noise spectrum using three coils: Coil 35mm away from center ANKE chamber Combined coils in same housing GHz range (one pickup loop) MHz range (several hundered loops) Fluxgate sensor kHz range Measurement of noise spectrum at COSY in MD week, July 2013

New Idea: Direct measurement of electron EDM for Permanent Electric Dipole Moments at COSY50 Could be an option for FNAL using the electrostatic Tevatron separators

for Permanent Electric Dipole Moments at COSY51 Timeline: Stepwise approach all-in-one machine for JEDI

Georg Christoph Lichtenberg ( ) “Man muß etwas Neues machen, um etwas Neues zu sehen.” “You have to make (create) something new, if you want to see something new” for Permanent Electric Dipole Moments at COSY