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Search for Electric Dipole Moments with Polarized Beams in Storage Rings

Search for Electric Dipole Moments with Polarized Beams in Storage Rings. Paolo Lenisa Università di Ferrara and INFN - Italy. PSTP 2013 – Charlottesville , Virginia, Sept. 9 th -13 th. Electric Dipoles. Definition. Charge separation creates an electric dipole. Orders of magnitude.

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Search for Electric Dipole Moments with Polarized Beams in Storage Rings

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  1. Search for Electric Dipole Moments with Polarized Beams in Storage Rings Paolo Lenisa Università di Ferrara and INFN - Italy PSTP 2013 – Charlottesville, Virginia, Sept. 9th-13th

  2. Search for EDM in Storage Rings ElectricDipoles • Definition Charge separationcreates an electricdipole • Orders ofmagnitude H2O molecule: permanent EDM (degenerate GS w/ different Parity) EDM 3∙10-26 e cm  chargeseparation < 5∙10-26 cm between u and d quarks

  3. EDM of fundamental particles Moleculeshave large EDM becauseofdegeneratedgroundstateswith different parity Elementaryparticles(includinghadrons) have a definite partiyandcannothave EDM Unless P and T reversalareviolated : magneticdipolemoment : electricdipolemoment (bothalignedwithspin) Permanent EDMs violate P and T Assuming CPT to hold, CP violated also

  4. CP violation • .Universedominatedby matter (and not anti-matter). • = 6x10-10 • Equalemountsof matter and antimatter atthe Big Bang. • CP violation in SM: 10-18expected • 1967: 3 Sacharovconditionsforbaryogenesis • Baryon numberviolation • C and CP violation • Thermal non-equilibrium • New sourcesof CP violationbeyond SM needed • Could manifest in EDM ofelementaryparticles Carina Nebula (Largest-seen star-birth regions in the galaxy)

  5. Theoreticalpredictions planned experiments No Standard Model Background!

  6. Experimental limits • EDM searches: onlyupperlimitsyet (in ) • E-fieldsacceleratecharged part.  search limited to neutral systems B B E • „Traditional“ approach: precessionfrequencymeasurement in B and E fields E µd hf+ = 2µB + 2dE hf- = 2µB - 2dE

  7. Experimental limits • EDM searches: onlyupperlimitsyet • E-fieldsacceleratecharged part.  search limited to neutral systems B B E • „Traditional“ approach: precessionfrequencymeasurement in B and E fields E µd hf+ = 2µB + 2dE hf- = 2µB - 2dE • (Tillnow) twokinds of experiments to measureEDMs: • Neutrons • Neutralatoms (paramagnetic/diamagnetic) No directmeasurement of electron or proton EDM yet

  8. Search for EDM in Storage Rings EDM ofchargedparticles: useofstorage rings PROCEDURE • Place particles in a storage ring • Alignspinalongmomentum ( freeze horizontal spinprecession) • Search for time developmentofverticalpolarization

  9. Search for EDM in Storage Rings Frozen spin method Spin motionisgovernedby Thomas-BMT equation: d: electricdipole moment m: magneticdipole moment TwooptionstogetridoftermsG (magiccondition): 1. Pure E ring (worksonlyforG>0, e.gproton): 2. Combined E.B ring (works also forG<0, e.gdeuteron)

  10. Storage ring projects pEDM in all electric ring at BNL Jülich, focus on deuterons, or a combinedmachine orat FNAL (from R. Talman) (from A. Lehrach) CW and CCW propagatingbeams Twoprojects: US (BNL or FNAL) andEurope (FZJ)

  11. Search for EDM in Storage Rings Feasibilityrequirements • POLARIMETER • The sensitivity to polarization must by large (0.5). • The efficiency of using the beam must be high (> 1%). • Systematic errors must be managed (< 10‒6). N.P.M. Brantjes et al. NIMA 664, 49 (2012) • POLARIZED BEAM • Polarization must last a long time (> 1000 s). • Polarization must remain parallel to velocity. • ELECTRIC FIELD, as large as practical (no sparks). • PROTON BEAM POSITION MONITORS (<10 nm) • SYSTEMATIC ERROR PLAN

  12. Search for EDM in Storage Rings Systematics • One major source: • Radial Br field mimics EDM effect • Example: d = 10-29 e cm with E = 10 MV/m • If mBr≈dErthis corresponds to a magnetic field: • (Earth magnetic field = 5 ∙ 10 -5 T) • Solution • Use two beam running clockwise and counterclockwise. • Separation of two beams sensitive to B

  13. EDM buildup time • Minimal detectable precession rad • Assuming • 109 turns needed to detect EDM signal • Spin aligned with velocity for t>1000 s ( spin coherence time next slides) Feasibility studies @ COSY

  14. COolerSYnchrotron(FZ-Jülich, GERMANY) • Momentum: <3.7 GeV/c • Circumference: 183 m • Polarized proton and deuteron • Beam polarimeter (EDDA detector ) • Instrumentation available for manipulationof - beam size (electron/stochastic cooling, white noise) - polarization (RF solenoid)

  15. EDDA beam polarimeter ASYMMETRIES Analyzing power VERTICAL polarization beam HORIZONTAL polarization Analyzing power • Beam moves toward thick target continuous extraction • Elastic scattering (large cross section for d-C)

  16. Search for EDM in Storage Rings Spin coherence time - Spin coherencealong Verticalpolarization not affected Atinjection all spinvectorsaligned (coherent) After some time, spinvectorsget out ofphaseandfullypopulatethecone

  17. Spin coherence time - Spin coherencealong Verticalpolarization not affected Atinjection all spinvectorsaligned (coherent) After some time, spinvectorsget out ofphaseandfullypopulatethecone - For (machines withfrozenspin) thesituationis different Longitudinal polarizationvanishes! Atinjection all spinvectorsaligned Later, spinvectorsare out ofphase in the horizontal plane In EDM machine observation time is limited by SCT.

  18. Decoherence: where does it arise? Y • LONGITUDINAL PHASE SPACE • Problem: beammomentum spread ( ) • E.g. Dp/p=1∙10-4Dns/ns=2.1x10-5 tpol=63 ms • Solution: use of bunchedbeam (<Dp/p> = 0) X Δp/p ≠ 0  Dns/ns≠ 0 RF-E Z P. Benati et al. Phys. Rev. ST, 049901 (2013) TRANSVERSE PHASE SPACE Problem: beamemittance 0  betatronoscillations Δx (Δy) from referenceorbit  Longerpath:  Higherparticlespeed Dns • E.g. q = 1∙mradtpol=9.9 s Possiblesolution to thisprobleminvestigatedat COSY

  19. Preparing a longitudinal polarized beam with RF-solenoid • 1) Froissart-Storascan • Identification spin resonancefrequency Hz Vertical polarization (L-R asymmetry) linear ramping in 40 s 2) Fixedfrequencymeasurements On resonance frequency (L-R asymmetry) COOLED BEAM time Vertical polarization 3) Solenoid on for half-cycle Vertical polarization = 0 Polarizationishorizontal (L-R asymmetry) time

  20. Measurement of the horizonthalSCT • No frozen spin: polarizationrotates in the horizonthalplaneat 120 kHz • DAQ synchronized with cyclotrhonfreqyency -> count turn number N • Compute total spin-precession angle (with spin-tunens=Gg) • Bin by phasearound the circle • Compute asymmetry in each bin Phaseprecession pie x x (U-D asymmetry) z Amplitude vs time • Derivation of horizontal spin coherence time 20 Spin coherencetime extracted from numericalfit

  21. Search for EDM in Storage Rings Performance OneStore 8x107turns Time stampsystem COSYorbit = 183 m Bunchingstarts Coolingstarts Full extraction starts • Spin-tuneand machine stability • Phase over time can be tracked with precision 10-8 • Stability of the ring magnets < 2x10-7 from Dennis Eversmann

  22. Beam emittancestudies BeamProfile Monitor y • Beampreparation • Pol. Buncheddeuteronbeamat p=0.97 GeV/c • Preparation of beam by electron cooling. • Selectiveincrease of horizontalemittance • Heatingthroughwhitenoise 1 fill x Quadraticdependence of spin tune on size of horizonthalbetatronoscillation Cooling+bunching Horizonthalheating Investigation of emittanceeffect on spin-coherence time: (betatronoscillation Longerpath different spin tune spin decoherence) Simulations (COSY Infinity) Measurementat COSY Narrowprofile Wide profile 0,6 s s (from A. Pesce) Beamemittanceaffects spin-coherence time

  23. Lengthening the SCT by COSY sextupoles Spin tune spread correction Particleorbitcorrection 6-pole field: Use of 6-poles wherebxfunctionismaximal Sextupolesatbxmax

  24. Results SCT Compensation by means of 6-pole fields: 1/tSCT = A<q2x> + a<q2x> A = originaleffect a = sextupoleeffect Choose a= -A Wide profile Medium profile Narrowprofile • Differenthorizontalprofilewidths • Differentslopes • Zero crossingindep. of width Same zero crossing! Sextupole fieldscan be used to increase

  25. Search for EDM in Storage Rings Conclusions • Non-zero EDM within the actualexperimentallimitsclear probe of new physics • Polarizedbeam in Storage Rings mightpavethe way to first directmeasurement of EDM of chargedparticles. • Technical challengesfor the EDM experimentin Storage Ring. • Long Spin CoherenceTime. • At the COSY ring dedicatedfeasibilitytests are underway. • SCT studies on a real machine • Emittanceaffects SCT of the storedbeam. • Sextupolefield can be effectivelyused to increase SCT. • .Furtherdevelopments: • Measurementrepetition in y – axisinhibithed by vertical machine acceptance • Compensation of (<DP/P>)2 with the sameprinciple • Test of spin-trackingcodes on the realmeasurement

  26. Search for EDM in Storage Rings Spin coherence time collaboration Z. Bagdasarian1, P. Benati2, S. Bertelli2, D. Chiladze1,3, J. Dietrich3, S. Dimov3,4, D. Eversmann5, G. Fanourakis6, M. Gaisser3, R. Gabel3, B. Gou3, G. Guidoboni2, V. Hejny3, A. Kacharava3, V. Kamerdzhiev3, P. Kulessa7, A. Lehrach3, P. Lenisa2, Be. Lorentz3, L. Magallanes8, R. Maier3, D. Michedlishvili1,3, W. M. Morse9, A. Nass3, D. Öllers2,3, A. Pesce2, A. Polyanskiy3,10, D. Prasun3, J. Pretz5, F. Rathmnann3, Y. K. Semertzidis9, V. Schmakova3,4, E. J. Stephenson11, H. Stockhorst3, H. Ströher3, R. Talman12, Yu. Valdau3,13, Ch. Weideman2,3, P. Wüstner14. 1Tbilisi State University, Georgia 2University and/or INFN of Ferrara, Italy 3IKP ForschungszentrumJülich, Germany 4JINR, Dubna, Russia 5III. PhysikalischesInstitut RWTH Aachen, Germany 6Institute of Nuclear Physics NCSR Democritos, Athens, Greece 7Jagiellonian University, Krakow, Poland 8Bonn University, Germany 9Brookhaven National Laboratory, New York, USA 10Institute of Theoretical and Experimental Physics, Moscow, Russia 11Center for Exploration of Energy and Matter, Indiana University, Bloomington, USA 12Cornell University, New York, USA 13Petersburg Nuclear Physics Institute, Gatchina, Russia 14ZEL ForschungszentrumJülich, Germany

  27. Search for EDM in Storage Rings

  28. Polarimetry of precessing horizontal polarization • Measurement of horizonalpolarization. • No frozen spin: polarizationrotatesat 120 KHz. x (U-D asymmetry) Polarim. Polarim. z Amplitude vs time • Derivation of horizontal spin coherence time 28 Spin coherencetime extracted from numericalfit

  29. Emittance studies on horizonthal SCT y Beampreparation 1 fill x Injection and acceleration Cooling Bunching Selectiveheating Extraction on target Cool & bunch Horizonthalheating RF solenoid SCT measurement Investigation of emittanceeffect on spin-coherence time: (betatronoscillation Longerpath different spin tune spin decoherence) 3 39 Time (s) 27 140 Narrowprofile Wide profile 0,6 s s Beamemittanceaffects spin-coherence time

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