Letter of Intent

1
Polarimeter Commissioning for a Search for an
Intrinsic Electric Dipole Moment on the Deuteron
Letter of Intent
E.J. Stephenson IUCF
Larger Context
Electric dipole moment (EDM) would be aligned
along spin. New method for charged particles uses
storage ring. Particles would precess about
rest-frame E-field (due to ß?B).
For hadrons, best limit is on neutron dn lt 6.3
? 10-26 ecm. Goal for this search 10-27
ecm. At this level, an EDM search is a test of
the Standard Model (predictions are lt 10-31
ecm) This probes an important range
(hep-ph/0402023).
This search is sensitive to nucleon EDM and NN
force contributions. (complementary to work
on heavier nuclei) Why the deuteron? small
anomalous magnetic moment high-quality
polarized sources and good polarimetry (simple
nuclear structure)
2
To allow EDM precession to develop, we must
(nearly) cancel in-plane precession from
anomalous moment.
PROPOSED RING
spin
V
E
vertical
B
Impose radial E-field to make ?a 0. This allows
where
radial
NOTE
Ring parameters p 0.7 GeV/c E 3.5
MV/m (balance between cost and polarimetry)
Rest-frame E 25.4 MV/m
NOTE ?a ? 0, so measure precession to learn
tilt of plane of rotation. So polarimeter
must operate continuously polarimeter must be
efficient with large analyzing power
so B 2.1 kG, r 9.6 m, T 126 MeV
?EDM 8 ? 10-7 rad/s
In 20 s, py gt 10-5 for dD 10-27 ecm
3
Project development of polarimeter at KVI and
COSY
Polarimeter will have carbon target, use C(d,X)
inclusively.
Measure cross section and analyzing power for
C(d,X) X p, d, t, (3He, 4He) Use the
in-beam polarimeter location at the KVI.
Energy range 64 180 MeV
2004
Design prototype based on Monte-Carlo using KVI
data.
Build prototype to fit COSY ring.
2005
Install in ring obtain operating point
calibrate check sensitivity to small
components check sensitivity to systematic
errors
publications on C(d,X) data and polarimeter
performance
4
Spin dependence
Plan to include inelastic and reaction channels
Rainbow scattering (semi-classical, large-L)
far-side and spin-orbit dominated bright
classical turning point diffracts different
spins to different angles (color) at/past
bright spot, m 1 dominates, thus Ay 1,
Ayy 1, Axx Azz 0.5, Axz 0
look at large angles
This may simplify polarimeter detectors by
allowing all charged particles to be used
(above cuts built into design).
5
EDM polarimeter

• IDEA
• make thick target defining aperture
• Coulomb scatter into it with thin target

ratio 40 MeV 10-5 1 GeV 6x10-4
lost to ring acceptance (2 kb)
cross section
(POMME efficiency several percent)
detector system
Coulomb
useful for spin (17 mb)
nuclear
U
defining aperture primary target
angle
L
extraction target gas jet
R
D
R
?
D
Target could be Ar gas (higher Z).
Detector is far enough away that
doughnut illumination is not an acceptance
issue ? lt R.
Hole is large compared to beam. Every- thing
that goes through hole stays in the ring. (It
may take several orbits to stop scattered particle
.)
Events must imbed far enough from hole to not
multiple scatter out of primary target, thus ? ltlt
D. ?, which is a large fraction of the deuteron
range, sets scale for polarimeter.
Target extracts by Coulomb scattering
deuterons onto thick main target. Theres not
enough good events here to warrant detectors.
Primary target may need to be iris to allow
adjustment of position and inner radius. It may
also need to be removed during injection.
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Conceptual Design
partial side view
other scintillators might be added
for monitoring or calibration checks
PMT
target control mechanism
scattered particles
target
beam pipe
end view showing array of 30 scintillators
beam direction
GOAL efficiency 1 analyzing
power 0.5
tapered target 25 mm thick at center
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COSY PLAN
Consultation with COSY engineering concerning
prototype requirements and choice of location in
the ring.
Installation and setup (cable runs, etc.).
3 engineering runs of about one week each (one
energy only)
optimization of rate and beam lifetime by
adjusting target thickness, aperture size, tune,
etc. (low currents) Estimate efficiency.
calibration of analyzing power against EDDA
polarization (or other polarimeter)
sensitivity to errors beam steering and
position changing conditions during store
(cooling, etc.) rate tolerance (high
currents)
sensitivity to changes in small components
(induced by small partial Siberian Snake in same
straight section)
Make modifications and improvements, return for
further testing. (May need additional
instrumentation or tracking in early stages.)
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People who have expressed an interest
E. J. Stephenson, and G. Noid Indiana University
Cyclotron Facility, Bloomington, IN 47408 USA
C.J.G. Onderwater, K. Jungmann, N.
Kalantar-Nayestanaki, J.G. Messchendorp, L.
Willmann, and H.W.E.M. Wilschut Kernfysisch
Versneller Instituut, Groningen, The Netherlands
R. Gebel, A. Lehrach, and B. Lorentz COSY, IKP,
Forschungszentrum Jülich, 52425 Jülich, Germany
W.M. Morse and Y. Semertzidis Brookhaven National
Laboratory, Upton, NY 11973 USA
J.P. Miller Boston University, Boston, MA 02215
USA
Additional collaborators are welcome! EC funding
will be sought.
author of letter of intent
spokesman of EDM proposal
student