A possible way to measure the deuteron EDM at COSY (A precursor to the dedicated EDM ring at IKP FZJ) W.Morse (BNL), N.Nikolaev (IKP FZJ & Landau Inst) & F.Rathmann (IKP FZJ) PSTP-2011, St.Petersburg12-17 September 2011

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. Future: Search for Electric Dipole Moments Frank Rathmann219th International Spin Physics Symposium

Layout: Why the deuteron EDM at COSY and at which accuracy? Radial RF E-field at COSY vs. Static E-ring Matching RF EDM-flipper to the spin precession in the H-field of a ring Polarimetry with oscillation horizontal spin Momentum spread and retention of the horizontal polarization Sensitivity to the deuteron EDM at COSY Summary: a stringent bound on the deuteron EDM at COSY is feasible

Upper bounds on the neutron EDM

There are two storage ring projects being pursued Strong need for a convincing precursor experiment at COSY Copied from R. Talman Copied from A. Lehrach

NEW: EDM search in time development of spin in a storage ring: A magic storage ring for protons (electrostatic), deuterons, … “Freeze“ horizontal spin precession; watch for development of a vertical component ! Frank Rathmann819th International Spin Physics Symposium Future: Search for Electric Dipole Moments particlep (GeV/c)E (MV/m)B (T) proton deuteron He One machine with r~30 m

Crucial idea from F.Rathmann: swap the role of the vertical and horizontal polarizations and the constant E-field for RFE-field EDM flipper EDM in the pure radial E-ring: buildup of the vertical polarization from the horizontal one Solution for the present day COSY: radial RFE- flipper to convert the vertical polarization to the horizontal one Need to cope with the precession of the horizonal polarization Bill Morse: fine tune the RF EDM flipper to spin precession in the ring magnetic field d < E-24 cm is a pefect target for the deuterom EDM

polarized beam in ring A one particle with magnetic moment “spin tune” “spin closed orbit vector” ring makes one turn if is simple fraction of periodic perturbing precession kick frequency resonances stable polarization if ║ Frank Rathmann10

a q Horizonal spin after flipper Beam Swap summation over discret passes for integration over time

In situ access to systematics? Swap the radial RFE field for the radial RFH field The magnetic moment shall do the same job as EDM Go down to micro- & nano-gauss to establish the sensitivity limit

Summary and Outlook: The deuteron EDM < 1 E-24 e cm is within the reach of COSY supplemented by RFE-flipper running at approx. 5 % of the ring frequency Similar upper bound is feasible for the proton An obviously long way from an ideal ring to the real thing plagued by systematics But there is an in situ access to sytematics via the magnetic moment of the deuteron (proton...)

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” Frank Rathmann1919th International Spin Physics Symposium

spin manipulation there is an for every point of the orbit Snakes (non-vertical B field) affect snakes flippers ramping through a resonance reverses spin closed orbit 180 o Frank Rathmann2019th International Spin Physics Symposium

Cooperation for test measurements at COSY Polarimetry: Spin coherence time: Copied from E. Stephenson

It´s all about systematics – stupid! … and money Summary – Statement #7

polarized beam in ring A one particle with magnetic moment “spin tune” “spin closed orbit vector” ring makes one turn if is simple fraction of periodic perturbing precession kick frequency resonances stable polarization if ║ Frank Rathmann2319th International Spin Physics Symposium

2 beams simultaneously rotating in a ring (CW, CCW) Approved BNL-Proposal: Goal for protons Technological challenges ! Carry out proof of principle experiments (demonstrators) at COSY Spin coherence time (1000 s) Beam positioning (10 nm) Continuous polarimetry (< 1ppm) E - field gradients (~ 17MV/m at 2 cm) Circumference ~ 200 m Frank Rathmann2419th International Spin Physics Symposium Future: Search for Electric Dipole Moments Mystery of matter-antimatter asymmetry