Report

Mitglied der Helmholtz-Gemeinschaft EDM Searches in storage rings July 5, 2012 Frank Rathmann Seminar on Precision Experiments in Storage Rings Topics Why EDMs? Search for EDMs using storage rings Two projects, at BNL and Jülich Spin coherence time First direct measurement Resonance Method with RF E(B)-fields Polarimetry Timeline of projects, cooperations, workshops Summary [email protected] EDM Searches in storage rings 2 What caused the Baryon asymmetry? Carina Nebula: Largest-seen star-birth regions in the galaxy What happened to the antimatter? (nB nB ) / n Observed 610-10 SM expectation ~10-18 WMAP+COBE (2003) Sakharov (1967): Three conditions for baryogenesis 1. B number conservation violated sufficiently strongly 2. C and CP violated, B and anti-Bs with different rates 3. Evolution of universe outside thermal equilibrium [email protected] EDM Searches in storage rings 3 Electric Dipole Moments (EDMs) Permanent EDMs violate parity P and time reversal symmetry T Assuming CPT to hold, combined symmetry CP violated as well. EDMs are candidates to solve mystery of matter-antimatter asymmetry may explain why we are here! [email protected] EDM Searches in storage rings 4 History of neutron EDM limits • Smith, Purcell, Ramsey PR 108, 120 (1957) • RAL-Sussex-ILL (dn 2.9 10-26 ecm) PRL 97,131801 (2006) Adopted from K. Kirch [email protected] EDM Searches in storage rings 5 Limits for Electric Dipole Moments EDM searches - only upper limits, in (up to now): equivalent Particle/Atom Current EDM Limit Future Goal Neutron − − − . × − − − × − − – − − – − Proton . × − − − Deuteron ? − − – × − Huge efforts underway to improve limits / find EDMs Sensitivity to NEW PHYSICS beyond the Standard Model 485. WE-Heraeus-Seminar (July 0406, 2011) Search for Electric Dipole Moments (EDMs) at Storage Rings http://www2.fz-juelich.de/ikp/edm/en/ [email protected] EDM Searches in storage rings 6 Why also EDMs of protons and deuterons? Proton and deuteron EDM experiments may provide one order higher sensitivity. In particular the deuteron may provide a much higher sensitivity than protons. Consensus in the theoretical community: Essential to perform EDM measurements on different targets (, , 3He) with similar sensitivity: • unfold the underlying physics, • explain the baryogenesis. [email protected] EDM Searches in storage rings 7 Search for Electric Dipole Moments NEW: EDM search in time development of spin in a storage ring: G 0 ds d E dt [email protected] “Freeze“ horizontal spin precession; watch for development of a vertical component ! EDM Searches in storage rings 8 Search for Electric Dipole Moments NEW: EDM search in time development of spin in a storage ring: G 0 ds d E dt “Freeze“ horizontal spin precession; watch for development of a vertical component ! A magic storage ring for protons (electrostatic), deuterons, … particle (/) (/) () proton . . . deuteron . −. . . . −. [email protected] EDM Searches in storage rings One machine with ~ m 9 Two storage ring projects being pursued BNL for protons all electric machine Jülich, focus on deuterons, or a combined machine CW and CCW propagating beams (from R. Talman) [email protected] EDM Searches in storage rings (from A. Lehrach) 10 BNL Proposal 2 beams simultaneously rotating in an all electric ring (cw, ccw) Approved BNL-Proposal Submitted to DOE Goal for protons d 2.5 1029 e cm (oneyear) p Circumference ~ 200 m Technological challenges ! • • • • Spin coherence time ( ) Beam positioning ( ) Continuous polarimetry (< ) E - field gradients (~ / ) Carry out proof of principle experiments (demonstrators) at COSY [email protected] EDM Searches in storage rings 11 Most recent: Richard Talmans concept for a Jülich all-in-one machine Iron-free, current-only, magnetic bending, eliminates hysteresis B A For more details, see Richard‘s lecture B A [email protected] EDM Searches in storage rings 12 The frozen spin Method For transverse electric and magnetic fields in a ring ( B E 0 ), anomalous spin precession is described by 2 m E q G G B G m p c x g 2 G 2 Magic condition: Spin along momentum vector 1. For any sign of , in a combined electric and magnetic machine GBc 2 2 E GBc 1 G 2 2 = radial = vertical 1. For > 0 (protons) in an all electric ring 2 m m G 0 p G p [email protected] 700 .74 MeV c EDM Searches in storage rings (magic) 13 Magic condition: Protons Case 1: field only r2 2 80 m3 He 0 .0 r2 2 50 md 0 .48 G Proton EDM 100 radius (m) 80 = 17 MV/m 60 r1( E) 40 = 24.665 m 20 0 5 10 15 20 25 30 35 E E-field (MV/m) [email protected] EDM Searches in storage rings 14 Magic condition: Protons Case 2: and fields >0 <0 magic energy [email protected] >0 <0 magic energy EDM Searches in storage rings 15 Magic condition: Deuterons and fields [email protected] EDM Searches in storage rings 16 Magic condition: Helions and fields [email protected] EDM Searches in storage rings 17 Parameters for Richard Talmans all-in-one machine Talman/Gebel give maximum achievable field of copper magnets of ~ 0.15 T. = particle (/) () (/) () proton . . . −. deuteron . . −. −. . . . −. • Fitting such a machine into the COSY building favors lower momenta. • Could someone please check this! [email protected] EDM Searches in storage rings 18 EDM at COSY – COoler SYnchrotron Cooler and storage ring for (polarized) protons and deuterons = 0.3 – 3.7 GeV/c Phase space cooled internal & extracted beams Injector cyclotron [email protected] COSY … the spin-physics machine for hadron physics EDM Searches in storage rings 19 EDM at COSY – COoler SYnchrotron Cooler and storage ring for (polarized) protons and deuterons = 0.3 – 3.7 GeV/c Phase space cooled internal & extracted beams Injector cyclotron [email protected] COSY … an ideal starting point for a srEDM search EDM Searches in storage rings 20 Spin closed orbit one particle with magnetic moment makes one turn nˆCO “spin closed orbit vector” “spin tune” S A SA ring A [email protected] 2 s stable polarization if S ║ nˆCO EDM Searches in storage rings 21 Spin coherence nˆCO We usually don‘t worry about coherence of spins along Polarization not affected! At injection all spin vectors aligned (coherent) After some time, spin vectors get out of phase and fully populate the cone Situation very different, when you deal with S nˆCO nˆCO Longitudinal polarization vanishes! At injection all spin vectors aligned [email protected] After some time, the spin vectors are all out of phase and in the horizontal plane In an EDM machine with frozen spin, observation time is limited. EDM Searches in storage rings 22 Estimate of spin coherence times (N.N. Nikolaev) One source of spin coherence are random variations of the spin tune due to the momentum spread in the beam G and is randomized by e.g., electron cooling cos(t ) cos(t ) sc Estimate: 1 f rev G 2 2 1 f rev G 2 2v 4 p p Tkin 100 MeV f rev 0.5 MHz sc ( p) 3103 s sc (d ) 5105 s Tkin 100 MeV 2 1 f rev 0.5 MHz Spin coherence time for deuterons may be ~ larger than for protons [email protected] EDM Searches in storage rings 23 First measurement of spin coherence time 2011 Test measurements at COSY Polarimetry: Spin coherence time: 5s 25 s 5s decoherence oscillation time capture [email protected] EDM Searches in storage rings from Ed Stephenson and Greta Guidoboni 24 Topics Why EDMs? Search for EDMs using storage rings Two projects, at BNL and Jülich Spin coherence time First direct measurement Resonance Method with RF E(B) –fields Polarimetry Timeline of projects, cooperations, workshops Summary [email protected] EDM Searches in storage rings 25 Resonance Method with RF E-fields spin precession governed by: (* rest frame) Two situations: 1. ∗ = 0 = (= 70 G for = 30 kV/cm) 2. ∗ = 0 = − RF E-field EDM effect no EDM effect vertical polarization stored d Polarimeter (dp elastic) This way, the EDM signal is accumulated during the cycle. • Statistical improvement over single turn effect is about: 1000s / 1s 105 . • Brings us in the 10−24 ecm range for . • But: Flipping fields will lead to coherent betatron oscillations, with hard to handle systematics. [email protected] EDM Searches in storage rings 26 Simulation of resonance Method with RF E-fields for deuterons at COSY Parameters: beam energy assumed EDM E-field Constant E-field Number of turns [email protected] = 50 MeV = 10−20 ecm 10 kV/cm RF = 1 m E-field reversed every −/() ≈ 21 turns Number of turns EDM Searches in storage rings 27 Simulation of resonance Method with RF E-fields for deuterons at COSY Parameters: beam energy assumed EDM E-field Linear extrapolation of P = 50 MeV = 10−20 ecm 10 kV/cm Px2 Pz2 for a time period of = 1000 s (= 3.7108 turns) EDM effect accumulates Polarimeter determines , and Number of turns [email protected] EDM Searches in storage rings 28 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. ∗ = 0 = − „Magic RF Wien Filter“ no Lorentz force „Indirect“ EDM effect Tilt of precession plane due to EDM RF E(B)-field stored d Polarimeter (dp elastic) Transverse polarization Observable: Accumulation of vertical polarization during spin coherence time Statistical sensitivity for in the range − to − range possible. • Alignment and field stability of ring magnets • Imperfection of RF-E(B) flipper [email protected] EDM Searches in storage rings 29 Operation of „magic“ RF Wien filter Radial E and vertical B fields oscillate, e.g., with = + ∙ rev = −54.151 × 103 Hz (here = 0). beam energy = 50 MeV Spin coherence time may depend on excitation and on chosen harmonics (see Kolya Nikolaev‘s lecture). [email protected] EDM Searches in storage rings 30 Simulation of resonance Method with „magic“ Wien filter for deuterons at COSY Parameters: beam energy assumed EDM E-field = 50 MeV = 10−24 ecm 30 kV/cm RF = 1 m Linear extrapolation of for a time period of = 1000 s = 3.7108 turns . EDM effect accumulates in . Preliminary, based on K. Nikolaevs derivation of the combined rotation matrices of E/B flipper and ring = 2 = −3.402 × 105 Hz turn number [email protected] EDM Searches in storage rings 31 Simulation of resonance Method with „magic“ Wien filter for deuterons at COSY Parameters: beam energy assumed EDM E-field = 50 MeV = 10−24 ecm 30 kV/cm RF = 1 m Linear extrapolation of for a time period of = 1000 s (= 3.7108 turns). EDM effect accumulates in turn number [email protected] EDM Searches in storage rings 32 Simulation of resonance Method with Magic Wien filter for deuterons at COSY Parameters: beam energy assumed EDM E-field = 50 MeV = 10−24 ecm 30 kV/cm = 1 m Linear extrapolation of for a time period of = 100000 s (= 3.71010 turns). EDM effect accumulates in turn number [email protected] EDM Searches in storage rings 33 Some polarimetry issues pC and dC polarimetry is the currently favored approach for the pEDM experiment at BNL srEDM experiments use frozen spin mode, i.e., beam mostly polarized along direction of motion, most promising ring options use cw & ccw beams. • scattering on C destructive on beam and phase-space, • scattering on C determines polarization of mainly particles with large betatron amplitudes, and • is not capable to determine = . • For elastic scattering longitudinal analyzing powers are tiny ( violates parity). Ideally, use a method that would determine (). [email protected] EDM Searches in storage rings 34 Exploit observables that depend on beam and target polarization beam 1 = (up) target (or beam 2) = Spin-dependent differential cross section for 1 2 + 1 2 1 1 →2+2 (sideways) (along beam) = 1 + + cos − + sin 0 + cos2 + sin2 + + sin cos + sin2 + cos 2 − + sin cos + + cos + + sin + Analyzing power = Spin correlations = () In scattering, necessary observables are well-known in the range 50 − 2000 MeV (not so for or ). [email protected] EDM Searches in storage rings 35 How could one do that, determine ? Suggestion 1: Use a polarized H storage cell target Detector CW CCW cell • Detector determines of cw & ccw beams separately, based on kinematics. • Alignment of target polarization along , , axes by magnetic fields. Leads to unwanted MDM rotations absolute no-go in EDM experiments. [email protected] EDM Searches in storage rings 36 How could one do that, determine ? Suggestion 2: Use colliding beam from external source cw beam = 0 0 probing beam = Detector 0 , , or 0 = 0 0 = 1 + + cos − + sin 0 + cos2 + sin2 + + sin cos Polarized ion source 2 − + sin cos + sin2 + cos(~10 MeV) + + cos + + sin + • Collide two external beams with cw and ccw stored beams. • Energy could be tuned to match detector acceptance. • Polarization components of probing low-energy beam can be made large, would be selected by spin rotators in the transmission lines. • Luminosity estimates necessary (Andro, David, Jörg) [email protected] EDM Searches in storage rings 37 How could one do that, determine ? Suggestion 3: Use directly reactions from colliding beams cw beam = ccw beam = CW Detector CCW = 1 + + cos − + sin 0 + cos2 + sin2 + + sin cos + sin2 + cos2 − + sin cos + + cos + + sin + Requires luminosity, -functions at IP should be rather small. • Advantage over suggestion 2. is that supports luminosity. • Disadvantage is that sensitivity comes mainly from terms with and . • Detailed estimates necessary (Andro, David, Jörg). [email protected] EDM Searches in storage rings 38 Luminosity estimate for the collider option () = Tmagic = 232.8 MeV ∙ 1 2 rev () (, ) = 4()2 Luminosity = 0.1 m Conditions: = 1 m 1 = 2 = 1011 = 4 () () 10 3.2 1 1 0.1 0.32 =1m = 10 m kinetic energy (MeV) Even under these very optimistic assumptions, event rate will be rather low. = × = 3.1 ∙ 1028 [cm−2 s−1 ] × 10−27 [cm2 mb−1 ] × 15[mb] ≈ − [email protected] EDM Searches in storage rings 39 Topics Why EDMs? Search for EDMs using storage rings Two projects, at BNL and Jülich Spin coherence time First direct measurement Resonance Method with RF E(B) –fields Polarimetry Timeline of projects, cooperations, workshops Summary [email protected] EDM Searches in storage rings 40 Technically driven timeline for pEDM at BNL 12 13 14 15 16 17 18 19 20 21 Two years R&D/preparation One year final ring design Two years ring/beam-line construction Two years installation One year “string test” [email protected] EDM Searches in storage rings 41 Stepwise approach in the JEDI project Step Aim / Scientific goal 1 2 Device / Tool Storage ring Spin coherence time studies Horizontal RF-B spin flipper COSY Systematic error studies Vertical RF-B spin flipper COSY COSY upgrade Orbit control, magnets, … COSY First direct EDM measurement at − RF-E(B) spin flipper Modified COSY 3 Built dedicated all-in-one ring Common magneticfor p, d, 3He electrostatic deflectors Dedicated ring 4 EDM measurement of p, d, 3He at − Dedicated ring Time scale: [email protected] Steps 1 and 2: < 5 years Steps 3 and 4: > 5 years EDM Searches in storage rings 42 srEDM cooperations International srEDM Network Institutional (MoU) and Personal (Spokespersons …) Cooperation, Coordination srEDM Collaboration (BNL) JEDI Collaboration (FZJ) (spokesperson Yannis Semertzidis) (spokespersons: A. Lehrach, J. Pretz, F.R.) Common R&D RHIC Beam Position Monitors (…) EDM-at-COSY Polarimetry Spin Coherence Time Cooling Spin Tracking (…) Study Group DOE-Proposal (submitted) CD0, 1, … First direct measurement Ring Design HGF Application(s) JEDI pEDM Ring at BNL [email protected] EDM Searches in storage rings 43 EDM Workshop at ECT* (Trento) October 1-5, 2012 http://www.ectstar.eu/ Organizing committee Jülich Hans Ströher [email protected] Frank Rathmann [email protected] Andreas Wirzba [email protected] Brookhaven Mei Bai [email protected] William Marciano [email protected] Yannis Semertzidis [email protected] [email protected] EDM Searches in storage rings 44 Summary • Measurements of EDMs are extremely difficult, but the physics is fantastic! • Two storage ring projects, at BNL and Jülich • All-in-one machine with copper-only magnets • Pursue spin coherence time measurements at COSY • First direct EDM measurement at COSY Resonance Method with RF E(B) -fields • Polarimeter concepts to be addressed by simulations • JEDI collaboration established [email protected] EDM Searches in storage rings 45