A possible way to measure the deuteron EDM at COSY

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 Rathmann 219th 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. TalmanCopied 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; watchfor development of a vertical component !

Frank Rathmann 819th International Spin Physics Symposium

Future: Search for Electric Dipole Moments

particle p (GeV/c) E (MV/m) B (T)proton 0.701 16.789 0.000

deuteron 1.000 -3.983 0.1603He 1.285 17.158 -0.051

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

AAS

one particle with magnetic moment

“spin tune”

“spin closed orbit vector”COn̂

s2AS

ring

makes one turn

if is simple fraction of periodic perturbing precession kick frequency

sresonances

stable polarizationS

if ║ COn̂

Frank Rathmann 10

Horizonal spin after flipper

cos' HH SS'HS

HS

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 (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”

Frank Rathmann 1919th International Spin Physics Symposium

spin manipulation

there is an for every point of the orbitSnakes (non-vertical B field) affect

snakesCOn̂

COn̂

flippersramping through a resonance reverses COn̂

spin closed orbit

180o

Frank Rathmann 2019th 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

AAS

one particle with magnetic moment

“spin tune”

“spin closed orbit vector”COn̂

s2AS

ring

makes one turn

if is simple fraction of periodic perturbing precession kick frequency

sresonances

stable polarizationS

if ║ COn̂

Frank Rathmann 2319th 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 Rathmann 2419th International Spin Physics Symposium

Future: Search for Electric Dipole MomentsMystery of matter-antimatter asymmetry