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Mitglied der Helmholtz-Gemeinschaft Precursor experiments to search for permanent electric dipole moments (EDMs) of protons and deuterons at COSY September 15, 2011 Frank Rathmann (with help from Andreas, Bernd, Bill, and Kolya) XIVth Int. Workshop on Polarized Sources, Targets & Polarimetry, St. Petersburg, Russia Topics Introduction Possible Precursor Experiments: 1. Depolarization using Snake and RF E Fields 2. Dual beam method (g-2 d) 3. Resonance Method with RF E-fields (Morse) 4. Resonance Method (Orlov, Morse, Semertzidis) Summary [email protected] Precursor experiments to search for EDMs at COSY 2 EDM at COSY – COoler SYnchrotron Cooler and storage ring for (polarized) protons and deuterons p = 0.3 – 3.7 GeV/c Phase space cooled internal & extracted beams COSY Injector cyclotron [email protected] … the spin-physics machine for hadron physics Precursor experiments to search for EDMs at COSY 3 EDM at COSY – COoler SYnchrotron Cooler and storage ring for (polarized) protons and deuterons p = 0.3 – 3.7 GeV/c Phase space cooled internal & extracted beams COSY Injector cyclotron [email protected] … an ideal starting point for a srEDM search Precursor experiments to search for EDMs at COSY 4 Search for Electric Dipole Moments Mystery of matter-antimatter asymmetry Electric dipole moment (EDM) A permanent EDM of a fundamental particle violates both parity (P) and time reversal symmetry (T). Assuming CPT to hold, the combined symmetry CP is violated as well. [email protected] Precursor experiments to search for EDMs at COSY 5 Future: Search for Electric Dipole Moments Mystery of matter-antimatter asymmetry EDM searches - only upper limits up to now: Huge efforts under way 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] Precursor experiments to search for EDMs at COSY 6 Future: Search for Electric Dipole Moments Mystery of matter-antimatter asymmetry NEW: EDM search in time development of spin in a storage ring: “Freeze“ horizontal spin precession; watch for development of a vertical component ! A magic storage ring for protons (electrostatic), deuterons, … particle p (GeV/c) E (MV/m) B (T) proton 0.701 16.789 0.000 deuteron 1.000 -3.983 0.160 3He 1.285 17.158 -0.051 [email protected] Precursor experiments to search for EDMs at COSY One machine with r ~ 30 m 7 An all-in-one machine: Protons E-field only r2 2 80 m3 He 0 .05 75 r2 2 50 md 0 .48 Gd Z Proton EDM 100 radius (m) 80 60 r1( E) 40 20 0 5 10 15 20 25 30 35 E E-field (MV/m) [email protected] Precursor experiments to search for EDMs at COSY 8 An all-in-one machine: Deuterons E and B fields Deuteron EDM Deuteron EDM radial E-field (MV/m) 0 radius (m) 20 10 B=0.1 T B=0.2 T B=0.3 T 0 100 200 300 400 kinetic energy ( MeV) [email protected] 500 5 10 B=0.1 T B=0.2 T B=0.3 T 15 100 200 300 400 500 kinetic en ergy (MeV) Precursor experiments to search for EDMs at COSY 9 An all-in-one machine: Helions E and B fields Helion EDM Helion EDM radial E-field (MV/m) 30 radius (m) 20 10 B=0.05 T B=0.1 T B=0.15 T 0 100 200 300 400 kinetic energy (MeV) [email protected] 500 20 10 0 B=0.05 T B=0.1 T B=0.15 T 100 200 300 400 500 kinetic energy (MeV) Precursor experiments to search for EDMs at COSY 10 Future: Search for Electric Dipole Moments Mystery of matter-antimatter asymmetry 2 beams simultaneously rotating in a ring (CW, CCW) Approved BNL-Proposal: Goal for protons d 2.5 1029 e cm (one year) p Circumference ~ 200 m Technological challenges ! • • • • Spin coherence time (1000 s) Beam positioning (10 nm) Continuous polarimetry (< 1ppm) E - field gradients (~ 17MV/m at 2 cm) Carry out proof of principle experiments (demonstrators) at COSY [email protected] Precursor experiments to search for EDMs at COSY 11 COSY: Concept for Snake • Should allow for flexible use at two locations • Fast ramping (< 30s) ANKE ANKE • Cryogen-free system PAX PAX • Should be available in 2012 Bdl (Tm) pn→{pp}sπ- at 353 MeV 3.329 PAX at COSY 140 MeV 1.994 PAX at AD 500 MeV 4.090 Tmax at COSY 2.88 GeV [email protected] 13.887 Precursor experiments to search for EDMs at COSY 12 PE 1: Use a combination of a snake and RF fields Snake Snake only Siberian snake turns spin closed orbit along longitudinal axis [email protected] Precursor experiments to search for EDMs at COSY 13 PE 1: Use a combination of a snake and RF fields RF E-field Snake RF E-field Snake + RF E-field, odd turns [email protected] Precursor experiments to search for EDMs at COSY 14 PE 1: Use a combination of a snake and RF fields RF E-field Snake RF E-field n P ( n ) P cos( 2 ) Snake + RF E-field, even turns 0 2 Snake + reversed RF E-fields depolarization [email protected] Precursor experiments to search for EDMs at COSY 15 PE 1: Use a combination of a snake and RF fields RF E-field Snake RF E-field P(n) P0 cos(2 )n Parameters of a proton EDM measurement: Tp=140 MeV ERF=1 MV/m, Lcavity=0.5 m Time of store 24h 6.310 2 10 turns =1 10-7 rad Sensitivity: • dp=10-17 ecm p=5.9 105 s • dp=10-18 ecm p=5.9 107 s [email protected] 0.8 0.6 P(n) P(n) • • • • • 0.4 -18 ecm dp=10 d=10^-18 e cm -17 ecm dp=10 d=10^-17 e cm 0.2 0 10 210 410 10 10 610 n n(number of turns) turns) (number of Precursor experiments to search for EDMs at COSY 16 PE 2: Dual Beam Method (equivalent to g-2 d) It seems possible to store protons and deuterons in COSY simultaneously. p and d at same momentum Polarimeter (determines pp and dp elastic) • Assume dp=10-24 ecm. • Determine invariant spin axis of protons using polarimeter. • Not clear whether one can get away with radial components of P only. • Determine invariant spin axis for deuterons using polarimeter. • Difference between the two invariant spin axes sensitive to dd. • Sensitivity similar to g-2 d: dd=10-19 ecm. [email protected] Precursor experiments to search for EDMs at COSY 17 PE 3: Resonance Method with RF E-fields (Bill and Kolyas variation of PE1) spin precession governed by: (* rest frame) Two situations: 1. B*=0 By = ER (= 70 G for ER=30 kV/cm) 2. E*=0 ER = - By vertical polarization RF E-field EDM effect no EDM effect Py drops Px2 Pz2 stored d grows Polarimeter (dp elastic) This way, the Edm signal gets accumulated during the cycle. Statistical improvement over PE 1 is about: 1000s / 1s 105 . Brings us in the 10-24 ecm range for dd [email protected] Precursor experiments to search for EDMs at COSY 18 PE 3: Simulation of resonance Method with RF E-fields and deuterons at COSY Parameters: beam energy assumed EDM E-field Constant E-field Number of turns [email protected] Td=50 MeV dd=10-20 ecm 10 kV/cm E-field reversed every -/(G) 21 turns Number of turns Precursor experiments to search for EDMs at COSY 19 PE 3: Simulation of resonance Method with RF E-fields and deuterons at COSY Parameters: beam energy assumed EDM E-field Td=50 MeV dd=10-20 ecm 10 kV/cm Linear extrapolation of P=sqrt(Px2+Py2) for a time period of sc=1000 s (=3.7108 turns) EDM effect accumulates Polarimeter determines Px, Py and Pz Number of turns [email protected] Precursor experiments to search for EDMs at COSY 20 PE 4: Resonance Method of EDM Measurements in SR Measurement using an all magnetic ring ds d (v B ) B dt * E • Sideways P, EDM produces growing Py • Using two sub-beams with different v and modulating v allows one to isolate d. • Sensitivity dd=10-29 ecm/yr • Idea was no longer pursued because systematic error is much larger. Orlov, Morse, Semertzidis PRL 96 (2006) [email protected] Precursor experiments to search for EDMs at COSY 21 Summary • Systematic error estimates for all PEs require reliable spin tracking tools. Top priority to make them available ASAP! • Next step: • Scrutinize potential of different PEs • Identify PE with best systematic limit on dp,d. [email protected] Precursor experiments to search for EDMs at COSY 22 Georg Christoph Lichtenberg (1742-1799) “Man muß etwas Neues machen, um etwas Neues zu sehen.” “You have to make (create) something new, if you want to see something new” [email protected] Precursor experiments to search for EDMs at COSY 23 Spare transparencies [email protected] Precursor experiments to search for EDMs at COSY 24 Frozen Spin Method (FSM) Spin vector Momentum vector 103 s Spin coherence time: for measurement on 10-29 e·cm level Lower energy particle …just right Higher energy particle G For B E 0, the spin precession (magnetic moment) relative to the momentum direction is given by E e 1 G G B 2 G , m 1 c [email protected] g 2 G 2 Precursor experiments to search for EDMs at COSY 25 Freezing Spin Precession with E-Fields 1 1 G 0 1 2 1 G G > 0 for γ > 1, if only electric fields are applied 1 m 1 p G G μp / μN = 2.792 847 356 (23) Gp = 1.7928473565 μd / μN = 0.857 438 2308 (72) Gd = -0.14298727202 μHe-3 / μN = -2.127 497 718 (25) G3He= -4.1839627399 Nuclear magneton: μN = eħ / (2mpc) = 5.050 783 24 (13) · 10-27 J T-1 Magic momentum for protons: p = 700.74 MeV/c [email protected] Precursor experiments to search for EDMs at COSY 26 polarized beam in ring one particle with magnetic moment makes one turn nˆCO “spin closed orbit vector” “spin tune” S A SA ring A 2 s stable polarization if S ║ nˆCO resonances if s is simple fraction of periodic perturbing precession kick frequency [email protected] Precursor experiments to search for EDMs at COSY 27 spin manipulation 180o snakes there is an nˆCO for every point of the orbit Snakes (non-vertical B field) affect nˆCO flippers ramping through a resonance reverses nˆCO 2 1 0 wspkk wpk w1pk w2pk [email protected] 1 2 3 spin closed orbit 4 4 Precursor experiments to search for EDMs at COSY 28 Machine acceptance In an ideal machine (like TSR-HD) → Single-Coulomb scattering at the target dominates beam loss cooled beam ring acceptance target lost K. Grigoriev et al., NIMA 599,130 (2009) [email protected] Precursor experiments to search for EDMs at COSY 29 Future: Time Reversal Invariance Test COSY-TRIC: P-even, T-odd COSY used as accelerator and detector: Total polarization correlation coefficient Ay,xz leads to relative difference of current slopes IBeam time PAX [email protected] Milestone: Operation of Precision BCT with I/I<10-4 Precursor experiments to search for EDMs at COSY 30 Need for a high precision BCT Status TRI Test at COSY • Slow fluctuations in the measured BCT signal exceed the noise band at higher frequencies Possible solution: Cryogenic Current Comparator, read out by low-temperature superconducting quantum interference device D. Eversheim Hyperfine Interact 193 (2009) A. Steppke, IEEE Trans. Appl. Superc. (2009) Highest resolution achieved: 250 pA/Hz [email protected] Precursor experiments to search for EDMs at COSY 31