Transcript Methods of lectric ipole oments in Storage Rings

Frascati, 5 October 2005
Methods of Electric Dipole
Moments in Storage Rings
Yannis K. Semertzidis
Brookhaven National Lab
•Parasitic to g-2
•Frozen spin
•Resonance

ds    
 Bd E
dt
Experimental Principle of g-2 or EDM:
• Polarize
• Interact:
in a B or E-Field
• Analyze as a function of time
Frascati, 5 October 2005
Yannis Semertzidis, BNL

ds    
 Bd E
dt
The Principle of g-2
Spin vector
Non-relativistic case
Momentum vector
eB
c 
m
•B
g eB
s 
2 m
g eB eB  g  2  eB
eB
 a   s  c 


 a  a

2 m m  2 m
m
Frascati, 5 October 2005
Yannis Semertzidis, BNL

ds    
 Bd E
dt
Spin Precession in g-2 Ring
(Top View)
Momentum
vector

Spin vector
e 
a  a B
m

Frascati, 5 October 2005
Yannis Semertzidis, BNL

ds    
 Bd E
dt
Effect of Radial Electric Field
Spin vector
• Low energy particle
• …just right
• High energy particle
Frascati, 5 October 2005
Yannis Semertzidis, BNL

ds    
 Bd E
dt
Effect of Radial Electric Field
Spin vector
• …just right, 29.3
for muons
(~3GeV/c)
Frascati, 5 October 2005
Yannis Semertzidis, BNL

ds    
 Bd E
dt
• The Muon Storage Ring:
B ≈ 1.45T, Pμ ≈ 3 GeV/c
•High Proton Intensity from AGS
Frascati, 5 October 2005
Yannis Semertzidis, BNL

ds    
 Bd E
dt
4 Billion e+ with E>2GeV
dN / dt  N 0 e
Frascati, 5 October 2005

t

1  A cos at  a 
Yannis Semertzidis, BNL

ds    
 Bd E
dt
Electric Dipole Moments in
Storage Rings
 


ds
 d  uB
dt


e.g. 1T corresponds to 300 MV/m for
relativistic particles
Frascati, 5 October 2005
Yannis Semertzidis, BNL

ds    
 Bd E
dt
Indirect Muon EDM limit from the g-2 Experiment
z


ωa
B





edm
s
β
x
e

m


   
aB  u  B 
2c

y 
   a   edm
edm
tan  
a
Ron McNabb’s Thesis 2003:
Frascati, 5 October 2005
19
 2.7  10 e  cm 95% C.L.
Yannis Semertzidis, BNL

ds  
 Bd E
dt
The Vertical Spin Component
Oscillates due to EDM
g-2 period
0 s
Frascati, 5 October 2005
Time
Yannis Semertzidis, BNL
8

d
s
s    B  d  E
dt
Effect of Radial Electric Field
Spin vector
• Low energy particle
Momentum vector
• …just right
• High energy particle
Frascati, 5 October 2005
Yannis Semertzidis, BNL

ds    
 Bd E
dt
Use a Radial Electric Field and a
Spin vector
• Low energy particle
Momentum vector
Frascati, 5 October 2005
Yannis Semertzidis, BNL

ds    
 Bd E
dt

Spin Precession in g-2 Ring
Momentum
(Top View)
vector
Spin vector
e 
a  a B
m

Frascati, 5 October 2005
Yannis Semertzidis, BNL

ds    
 Bd E
dt
Spin Precession in EDM Ring
Momentum
(Top View)
vector

Spin vector

a  0
Frascati, 5 October 2005
Yannis Semertzidis, BNL

ds    
 Bd E
dt
(U-D)/(U+D) Signal vs. Time
Frascati, 5 October 2005
Yannis Semertzidis, BNL

ds    
 Bd E
dt
z


ωa
B
 


e

m


   
aB  u  B 
2c

edm
s
β
x

y 
   a   edm
edm
tan  
a
Frascati, 5 October 2005
Yannis Semertzidis, BNL

ds    
 Bd E
dt
Vertical Spin Component without
Velocity Modulation (deuterons)
Frascati, 5 October 2005
Time
Yannis Semertzidis, BNL

ds    
 Bd E
dt
Velocity-0.35
Velocity Modulation in Phase with g-2 Precession
Frascati, 5 October 2005
Yannis Semertzidis, BNL

ds    
 Bd E
dt
Vertical Spin Component with
Velocity Modulation at a
Frascati, 5 October 2005
Time
Yannis Semertzidis, BNL

ds    
 Bd E
dt
Vertical Spin Component with
Velocity Modulation (longer Time)
0 s
Frascati, 5 October 2005
Time
Yannis Semertzidis, BNL
75

d
s
s    B  d  E
dt
EDM Spin Resonance Method
Some of Y. Orlov’s main ideas:
• Synchrotron tune = (a-N), a=(g-2)/2, N=0,1,2,…
• Cancel systematics by the two half beam storage
at different vertical tunes
• Use n=1 in the dipole magnets, and p=1 mainly
to keep the phase of the g-2 rotation linear with t.
• D-function0 at straight section…
Frascati, 5 October 2005
Yannis Semertzidis, BNL

ds    
 Bd E
dt
Two half beam technique
This tune makes its
spin more sensitive
to background
See talk by B. Morse tomorrow
Frascati, 5 October 2005
Yannis Semertzidis, BNL

ds    
 Bd E
dt
Other Issues
• Spin coherence time. I.B. Vasserman et al., Phys. Lett.
B198, 302 (1987); A.P. Lysenko, A.A. Polunin, and
Yu.M. Shatunov, Particle Accelerators 18, 215 (1986).
• RF-system: frequency, shape, strength, normal/SC. Is
partial linearization needed? C. Ohmori, et al., 14th
Symposium on Accelerator Science and Technology,
Tsukuba, Japan, Nov. 2003; M. Yamamoto et al., PAC99.
Frascati, 5 October 2005
Yannis Semertzidis, BNL

ds    
 Bd E
dt
Storage Ring EDMs
• Interesting Physics
• Study the ideas, improve design
• Contribution level to this effort
Frascati, 5 October 2005
Yannis Semertzidis, BNL

ds    
 Bd E
dt
Summary
• ~end of the year Letter of Intent
• We need help to develop the final ring
lattice and tolerances on parameters
• Goal for a proposal by the end of next year
• A unique opportunity for a significant
contribution to the physics of EDM
Frascati, 5 October 2005
Yannis Semertzidis, BNL

ds    
 Bd E
dt
Nuclear Scattering as Deuteron EDM polarimeter
Ed Stephenson’s
IDEA:
- make thick target defining aperture
- scatter into it with thin target
detector
system
Alternative way: resonant slow extraction (Y. Orlov)
U
“defining aperture”
primary target
L
“extraction”
target - ribbon
R
D
Target could be
Ar gas (higher Z).
Target “extracts” by
Coulomb scattering
deuterons onto thick
main target. There’s
not enough good
events here to
warrant detectors.
Frascati, 5 October 2005
D
Δ
Hole is large
compared to
beam. Everything that goes
through hole
stays in the
ring.
Yannis Semertzidis, BNL
R
Detector is far enough
away that doughnut
illumination is not an
acceptance issue:
Δ < R.

ds    
 Bd E
dt