Transcript 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
Future: Search for Electric Dipole Moments
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.
Frank Rathmann
19th International Spin Physics Symposium
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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
Copied from R. Talman
Copied from A. Lehrach
Strong need for a convincing precursor experiment
at COSY
Future: Search for Electric Dipole Moments
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
Frank Rathmann
19th International Spin Physics Symposium
One machine
with r~30 m
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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 RFEflipper 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
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
Frank Rathmann
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Horizonal spin after flipper
a
'
S H  S H    cos
SH
'
S
H
q
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
19th International Spin Physics Symposium
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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
Frank Rathmann
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2
3
spin
closed
orbit
4
4
19th International Spin Physics Symposium
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Cooperation for test measurements at COSY
Polarimetry:
Spin coherence time:
Copied from E. Stephenson
Summary – Statement #7
It´s all about systematics – stupid!
… and money
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
Frank Rathmann
19th International Spin Physics Symposium
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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
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
Frank Rathmann
19th International Spin Physics Symposium
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