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February 24, 2014 Frank Rathmann on behalf of JEDI

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.

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February 24, 2014 Frank Rathmann on behalf of JEDI

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

  2. 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. Search for Permanent Electric Dipole Moments at COSY

  3. Outline Threerecentachievements Proposed experimental investigations: • Spin coherence time studies (contin. of #176) • RF Wien Filter • Systematic study of machine imperfections using two straight section solenoids Beam request Search for Permanent Electric Dipole Moments at COSY

  4. A 1: Spin coherence time Sextupole correctionsofhigherordereffectsyield Search for Permanent Electric Dipole Moments at COSY

  5. A 2: Spin tune determination Using time stampingtechniquefromUp/Do asymmetry Spin tune determined to in . Average in one cycle () known to . Understandimplicationsforfutureprecisionexperiments. Search for Permanent Electric Dipole Moments at COSY

  6. A 3:Harmonicdependenceof Observedoscillating, driven by RF solenoid at different harmonics 235 MeV Spin coherence time (s) Beam energy (MeV) Theory: N.N.Nikolaev Observation ofenhancementsoffor p (and d) requiresmore flexible polarimeter Search for Permanent Electric Dipole Moments at COSY

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

  8. First 2-D Map: vs MXS vs MXG Location of best SCT is closely associated with location of vanishing chromaticity. MXS +Best SCT points for large horizontal emittance + + 40 + + +Best SCT points for large Δp/p (longitudinal) + • Eachsextupolefieldscanlocatesonepoint on 2D map • Beam set up to emphasize different sources of decoherence, which can be corrected with sextupole fields. + + + + + 20 ξX = 0 + + + ξY = 0 + + 0 20 Units: percentof power supply full scale. MXG Search for Permanent Electric Dipole Moments at COSY

  9. Chromaticitystudies (tests in week 7) • Chromaticity definesthe tune changewithrespecttomomentumdeviation • Strong connectionbetweenandobserved. • COSY Infinitybasedmodelpredicts negative naturalchromaticities and . • Measurednaturalchromaticity: and • changedfrom 1 to 3 in 2013, althoughsimilarmachinesettingswereused. • Tobestudied: • Vary sextupolesofarcsandstraights: benchmarkchanges in model. • Varyquadrupolesandorbitexcitationstosearchforsourcesofvariations. • Examinelongtermstability. • Rampupdipolemagnetstoinvestigateinfluenceofmachinehistory on . Search for Permanent Electric Dipole Moments at COSY

  10. Measurement ofchromaticity • Twomethodsfor beam energyshiftapplied • Variation ofelectron cooler voltage • Variation ofcavityfrequency • Tune measurement: • Sweepfrequencyfor beam excitationandmeasureresponsetolocatebetratronfrequency • MeasurerevolutionfrequencyusingSchottkyspectrum Vertical Horizontal Search for Permanent Electric Dipole Moments at COSY

  11. Chromaticity: Arcsextupoles Threefamilies in thearcs: (MXS, MXL, MXG) Non-vanishingdispersion in thearcs, large influenceofchromaticityexpected Measurement / Model (change per %) MXS: / / MXL: / / MXG: / / Search for Permanent Electric Dipole Moments at COSY

  12. Chromaticity: Straight sectionsextupoles Test ofcombinedfamiliyoffourstraightsectionsextupoles(MXT: 2-3-10-13) Dispersion minimized in straights, noimpact on chromaticityexpected Straight sectionsextupolesshownoeffect on chromaticity Search for Permanent Electric Dipole Moments at COSY

  13. Spin coherence time studies: Required time 2 weeks are requested to further explore ways to improve the SCT. • Make 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. • Explore straight section sextupoles (no effect on chromaticity) • Sensitivity of SCT seen before (but weaker). Does different degree of freedom help? • Additional information would be useful: • Revisit RF-solenoid-induced oscillations at low field • Present analysis hampered by differential extraction on ridge target. • Explore contribution of emittance to SCT in white noise extraction Search for Permanent Electric Dipole Moments at COSY

  14. 2. RF Wien Filter Precursor EDM concept: Use RF Wien filtertoaccumulate EDM signal Insert RF-dipoleintoceramicchamber Search for Permanent Electric Dipole Moments at COSY

  15. RF Wien Filter: Field calculations Main fieldcomponent at , Main fieldcomponent at , Integral compensationof Lorentz force at Search for Permanent Electric Dipole Moments at COSY

  16. Commissioning: • Pulsedmode, pulses, each long, • BPM sensitivityat betatronsidebandfrequencyused to adjustandtomatch Wien filtercondition, • Diagnosis using COSY BCT • Compensationachieved down to ~7 % beam loss. RF Wien Filter: First testswith beam Matching ofphaseofat Matching of RF fieldto RF at Beam loss (%) Beam loss (%) Requested2 weeksof beam time will beusedtofullycommissiontheRF Wien filter, shoulddo same job as RF solenoid. E-B phase () Search for Permanent Electric Dipole Moments at COSY

  17. Systematic study of machine imperfections using two straight section solenoids Systematiceffectsfrommachineimperfectionslimittheachievableprecision in a precurorexperiment using an RF Wien filter. • COSY providestwosolenoids in oppositestraightsections: • oneofthecompensationsolenoidsofthe 70 kV cooler: , • The mainsolenoidofthe 2 MV cooler: . • Bothareavailabledynamically in thecycle, i.e., theirstrengthcanbeadjusted on flattop. Idea: The precisedeterminationofthespin tune canbeexploitedtomap out theimperfectionsof COSY. Search for Permanent Electric Dipole Moments at COSY

  18. Imperfection kick: Deuterons at MeV Ideal machine with vanishing static imperfections: Saddle point at the origin Intrinsic imperfection kick shifts saddle point away from origin sea level at Location of imperfection: The requested 2 weeksof beam time shallbeusedtostudystaticimperfectionswithartificialspinrotations and inducedbytwostraightsectionsolenoids. Search for Permanent Electric Dipole Moments at COSY

  19. Beam Request • We request in total 6 weeksof beam timefortheactivities: • Spin coherence time studies (contin. of #176) (2 weeks), • RF Wien Filter (2 weeks), • Systematic study of machine imperfections using two straight section solenoids (2 weeks), • preceededby1 MD week. • Investigationsdifficult, require time consumingmachinetuning. Beam time shouldbescheduledassingle block. Search for Permanent Electric Dipole Moments at COSY

  20. Backup slides Search for Permanent Electric Dipole Moments at COSY

  21. Precursorexperiments: RF methods Methodbased on makingspinprecession in machine resonant withorbitmotion Twoways: Use an RF devicethatoperates on someharmonicsofthespinprecessionfrequency Operate ring on an imperfectionresonance Useexistingmagneticmachinesforfirstdirect EDM measurements Search for Permanent Electric Dipole Moments at COSY

  22. Precursorexperiments: 1. ResonanceMethodwith „magic“ RF Wien filter Avoidscoherentbetatronoscillationsof beam. Radial RF-E andvertical RF-B fieldstoobservespinrotation due to EDM. Approach pursuedfor a firstdirectmeasurementat COSY.  „Magic RF Wien Filter“no Lorentz force Indirect EDM effect Observable: Accumulationofverticalpolarizationduringspincoherence time RF E(B)-field In-plane polarization stored d Polarimeter (dpelastic) • Statistical sensitivityfor in therange to rangepossible. • Alignmentandfieldstabilityof ring magnets • Imperfectionof RF-E(B) flipper Search for Permanent Electric Dipole Moments at COSY

  23. Precursorexperiments: 1. ResonanceMethodfordeuteronsat COSY Parameters: beam energy assumed EDM E-field • EDM effect accumulates in Search for Permanent Electric Dipole Moments at COSY

  24. 1. ResonanceMethodOperation of „magic“ RF Wien filter Radial E andvertical B fieldsoscillate, e.g., with(here). beam energy • Spin coherence time may depend on excitation and on harmonics 𝐾. Search for Permanent Electric Dipole Moments at COSY

  25. Precursorexperiments: 1. ResonanceMethodfordeuteronsat COSY Parameters: beam energy assumed EDM E-field EDM effectaccumulates in Linear extrapolationoffor a time periodofyields a sizeable. Search for Permanent Electric Dipole Moments at COSY

  26. Development: RF E/B-Flipper (RF Wien Filter) Upgrade testflipperwithelectrostaticfieldplatesready end ofyear. Buildlower power versionusing a striplinesystem Build high-power versionofstriplinesystem () Work byS. Mey, R. Gebel (Jülich) J. Slim, D. Hölscher (IHF RWTH Aachen) Search for Permanent Electric Dipole Moments at COSY

  27. Precursorexperiments: 2. Resonant EDM measurementwithstaticWien Filter Machineoperated on imperfectionspinresonanceat withoutstatic WF Spin rotation in phasewithorbitmotion Similaraccumulationof EDM signal, systematicsmoredifficult, strengthofimperfectionresonance must besuppressedbyclosed-orbit corrections. Search for Permanent Electric Dipole Moments at COSY

  28. 1 Make 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. ξX,Y = 0 2 Explore 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: 3 Revisit RF-solenoid-induced PY oscillations at low field. Present analysis hampered by differential extraction on ridge target. 4 Explore contribution of emittance in white noise extraction to SCT. Search for Permanent Electric Dipole Moments at COSY

  29. 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 HORIZONTAL POLARIZATION Beam set up to emphasize different sources of decoherence, which can be corrected with sextupole fields. MXS + Example of data measured with the time-marking DAQ system + 40 + + SCT Best SCT pointsfor large Δp/p (longitudinal) + + + Best SCT points for large horizontal emittance + + + 20 Zero crossing of inverse slope locatesbest SCT. + FIRST 2-D MAP Each sextupole field scan locates one point on 2-D map. + + Initial Polarization Slope MXG + + signs changed to show linear effect black = spin down blue = spin up 20 0 Units are in percentof power supplyfull scale. Search for Permanent Electric Dipole Moments at COSY

  30. 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. MXS Slopes scaled to percent units. Offsets are arbitrary. + + 40 + + Best SCT pointsfor large Δp/p (longitudinal) Best SCT points for large horizontal emittance + + + COSY-Infinity calculations by Marcel Rosenthal + + Chromaticity effects are planar. Sextupoles adjust constant term. + 20 ξX = 0 + + + ξY = 0 Units are in percent of power supply full scale. best fit to chromaticity data + + 20 0 MXG Search for Permanent Electric Dipole Moments at COSY

  31. Stability • 5 days/nightsofmeasurement MXS @ 2%shiftof +0.3 expected MXS @ 2%shiftof -0.22 expected Measurementsusingcavity (method 2) Search for Permanent Electric Dipole Moments at COSY

  32. MachineHistory • Super Cycle: B-Field ofbendingdipoles 1. cycle: noinjection, dipolerampedto larger targetmomentafor 4- 5 seconds2. cycle: usualmeasurementcycle Target momentaof additional ramp: 1: 2028 MeV/c 2: 2513 MeV/c 3: 3097 MeV/c 4: 3700 MeV/c 5: cycle 1 removed(defaulttargetmomentum: 970 MeV/c) Additíonaldipoleramp measurement time restoring restoring increasing decreasing Search for Permanent Electric Dipole Moments at COSY

  33. Physics: Fundamental Particles Charge symmetricNoEDM () : MDM : EDM Do particles(e.g., electron, nucleon) have an EDM? Search for Permanent Electric Dipole Moments at COSY

  34. Physics: Symmetries Physical laws are invariant under certain transformations • T-Symmetry: C-parity(or Charge parity): • Changessignof all quantizedcharges • electrical charge, • baryon number, • lepton number, • flavor charges, • Isospin (3rd-component) Parity: Search for Permanent Electric Dipole Moments at COSY

  35. EDMs: DiscreteSymmetries Not Charge symmetric (aligned w/ spin) Permanent EDMs violate P and T. Assuming CPT to hold, CPviolated also. Search for Permanent Electric Dipole Moments at COSY

  36. Physics: Potential of EDMs J.M. Pendlebury: „nEDMhaskilledmoretheoriesthananyothersingleexpt.“ Search for Permanent Electric Dipole Moments at COSY

  37. Principle: Frozen spin Method Fortransverseelectricandmagneticfields in a ring ( ), anomalousspin precession isdescribedbyThomas-BMT equation: x Magic condition: Spin alongmomentumvector Foranysignof, in a combinedelectricandmagneticmachine 2. For(protons) in an all electric ring (magic)  Magic rings tomeasure EDMs offreechargeparticles Search for Permanent Electric Dipole Moments at COSY

  38. Beat systematics: BNL Proposal 2 beamssimultaneouslyrotating in an all electricring (cw, ccw) CW & CCW beams cancels systematic effects Status: ApprovedBNL-Proposal Submittedto DOE Interest FNAL! Goal forprotons Manytechnologicalchallengesneedtobemet Search for Permanent Electric Dipole Moments at COSY

  39. srEDMsearches: Technogicalchallenges • Charged particle EDM searchesrequiredevelopmentof a newclassof high-precisionmachineswithmainlyelectricfieldsforbendingandfocussing. • Relatedtopics: • Electric fieldgradients • Spin coherence time • Continuous polarimetry • Beam positioning • Spin tracking These issues must beaddressedexperimentallyatexistingfacilities Search for Permanent Electric Dipole Moments at COSY

  40. Challenge: Electric field for magic rings Rfieldonly Challenge toproduce large electricfieldgradients Search for Permanent Electric Dipole Moments at COSY

  41. Challenge: Niobium electrodes DPP stainlesssteel fine-grainNb Show oneslide on JLAB data HV devices large-grainNb single-crystalNb large-grainNb Large-grainNbatplateseparationof a few cm yields ~20 MV/m Search for Permanent Electric Dipole Moments at COSY

  42. Challenge: Electric field for magic rings Electrostatic separatorsatTevatronusedtoavoidunwanted interactions - electrodesmadefromstainlesssteel L~2.5 m Routine operationatspark/Year atMV/m ~July 2013: Transfer ofseparatorunit plus equipmentfrom FNAL to Jülich Need todevelopnewelectrodematerialsandsurfacetreatments Search for Permanent Electric Dipole Moments at COSY

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

  44. Challenge: Spin coherence time Weusuallydon‘tworryaboutcoherenceofspinsalong Polarization not affected! Atinjection all spinvectorsaligned (coherent) After some time, spinvectorsget out ofphaseandfullypopulatethecone Situation very different, whenyou deal withmachineswithfrozenspin. Longitudinal polarizationvanishes! Atinjection all spinvectorsaligned Later, spinvectorsare out ofphase in the horizontal plane In an EDM machine with frozen spin, observation time is limited. Search for Permanent Electric Dipole Moments at COSY

  45. Challenge:SCT stimates (N.N. Nikolaev) Onesourceofspincoherencearerandomvariationsofthespin tune due tothemomentumspread in the beam and israndomizedby e.g., electroncooling Estimate: Spin coherence time for deuterons may be 𝟏𝟎𝟎× larger than for protons Search for Permanent Electric Dipole Moments at COSY

  46. EDM at COSY: COolerSYnchrotron Cooler andstorage ring for(polarized)protonsanddeuterons Phase space cooledinternal & extractedbeams COSY … the spin-physics machine for hadron physics … an ideal startingpoint for a srEDMsearch Injector cyclotron Search for Permanent Electric Dipole Moments at COSY

  47. New Idea: Ivan Koop‘sspinwheel B By appropriatechoiceofmagneticfield, thespinvectorrotates fast frequenciesoftheorder kHz Jülich hasexpertise in SQUIDs, state-of-theartmeasurementsallowforis ( This wouldrevolutionizethewayweconceive EDM (and in generalpolarization) experiments, becausefrequenciesbecomedirectlymeasureable. Search for Permanent Electric Dipole Moments at COSY

  48. HowIvan‘sspinwheelwouldwork? Frequency Find thevalueof B where spinprecessionfrequencydisappears B field Search for Permanent Electric Dipole Moments at COSY

  49. SQUIDs: Precision toolsforaccelerators • Possibleapplications in accelerators, all ofwhichareneededforsrEDMexperiments • Beam currenttransformers • Beam positionmonitors • Beam polarimeters • Begin developmentwith a measurementofthenoisespectrum 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 ofnoisespectrumat COSY in MD week, July 2013 Search for Permanent Electric Dipole Moments at COSY

  50. New Idea: Directmeasurementofelectron EDM • Bill Morse (BNL EDM): , , • Nobody knowswhere CPV ishiding, maywellbe in theleptonicsector • Needs a dedicated R&D effort • Veryattractive: • Tests all ingredientsofsrEDMexperimentswith • Coulddevelopinto an independentlong-term project • Polarimetry is an issue • Goal: Couldbe an optionfor FNAL usingtheelectrostatic Tevatron separators Search for Permanent Electric Dipole Moments at COSY

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