wolfgang quint ([email protected])
DESCRIPTION
Penning trap measurement of the magnetic moment of the antiproton. Wolfgang Quint ([email protected]). GSI Darmstadt, Germany. Villars Meeting, Sept. 25, 2004. m p : magnetic moment g p : g-factor s: spin m N : nuclear magneton. B. g-Factor of the antiproton. - PowerPoint PPT PresentationTRANSCRIPT
Atomic Physics
Wolfgang Quint ([email protected])
GSI Darmstadt, Germany
Penning trap measurement of thePenning trap measurement of themagnetic moment of the antiprotonmagnetic moment of the antiproton
Villars Meeting, Sept. 25, 2004Villars Meeting, Sept. 25, 2004
Atomic Physics
B
g-Factor of the antiproton
hs
gpN
p
p: magnetic momentgp: g-factors: spinN: nuclear magneton
proton: gp = 2×2.792847337(29)*accuracy: 10-8
antiproton: gpbar = 2×2.800(8)* accuracy: 10-3
*Particle Data Group
Atomic Physics
Bm
eg
p
pL 2 B
m
e
pc
cyclotron frequency:cyclotron frequency:Larmor precessionfrequency:
Larmor precessionfrequency:
c
Lpg
2
g-Factor of the antiproton
B: magnetic field in Penning trap
Atomic Physics Geonium: Single electron in a Penning trap
anomaly transition
(2 , )
(1 , )
(0 , )
(nc , )
(1 , )
(0 , )
(nc , )
Electron
CPT
Positron
(2 , )
(1 , )
(0 , )
(nc , )
(1 , )
(0 , )
(nc , )
anomaly transition
(nc: cyclotron quantum number)
Figure of merit for CPT violation(Bluhm, Kostelecky, Russell):
212 102,12/)( cmeaa
(Dehmelt, Van Dyck)
Atomic Physics Single antiproton in a Penning trap
Proton
CPT
Figure of merit for CPT violation(Bluhm, Kostelecky, Russell):
252 1012/)( cmpaa
spinflip transition
(nc , )
(nc , )spinflip transition
(nc , )
(nc , )
Antiproton
(expected accuracy)
Atomic Physics
z = 1 MHz
B
compensationelectrode
ring electrode
end cap
end cap
compensationelectrode
dEp/dt = Pcool = -I2R
cooling
LRCU = I R
Electronic detection of a single antiproton
c2-
2 z
2+2
Atomic Physics
-0,2 -0,1 0,0 0,1 0,2 0,3 0,4 0,5
0,00
0,02
0,04
0,06
0,08
0,10
0,12
relativistic frequency shift:D
c/
c = - E
c/mc2, E
c = 5 eV
Dc = - 0,5 Hz
g = (1 - ß2)-1/2 = 1,000 000 005
mgeB
c =
(This antiproton wastrapped for 60 days,until Jan. 18, 1993,7 o'clock)
Cyclotron Resonance of aSingle Antiproton
Dc = 11 mHz
linewidthDc/
c = 1,2 . 10-10
elec
tron
ic s
igna
l [m
V2 ]
cyclotron frequency c - 89 258 427 Hz
Cyclotron resonance of a single antiproton
measured at LEAR,1993(G. Gabrielse,D. Phillips,W. Quint)
Atomic Physics
BM
q
ionc
Ion cyclotron frequency:Ion cyclotron frequency:
Bm
eg
e
JL 2
Larmor precession fre-quency of bound electron:
Larmor precession fre-quency of bound electron:
B
ion
qM
ee
m
ionc
L
Jg
2
G-Factor of the bound electron in H-like ions
new value for the electron mass
Atomic Physics
-20 -10 0 10 20
60µV
80µV
100µV
120µV
140µV
160µV
° non-destructive detection at T = 4 Kelvin
2,2 Hz
Measurement of the axial frequency
of a single C5+
-ion
elec
tron
ic d
etec
tion
sig
nal
axial frequency - 343 033 Hz
Atomic Physics
0 200 400 600 800364343.0
364343.5
364344.0
364344.5
axia
l fre
quen
cy [
Hz]
time [min]
spin up
spin down
Quantum jumps of a single hydrogen-like ion
• Axial frequency depends on spin direction due to continuous Stern-Gerlach effect
Atomic Physics
spin has magneticmoment
magnetic bottle:B(z) = B0 + B2z2
magnetic energy:Emagn(z) = B0 B2z2
attractive orrepulsive force
axial frequency =f (spin direction
Continuous Stern-Gerlach effect
Atomic Physics
precisiontrap
analysistrap E
lectric potential shape
Mag
netic
fiel
d lin
es
Principle:
• Excitation of spin-flip in precision trap (homogeneous magnetic field)
• Detection of spin-flip in analysis trap (inhomogeneous magnetic field for spin-flip detection)
Principle:
• Excitation of spin-flip in precision trap (homogeneous magnetic field)
• Detection of spin-flip in analysis trap (inhomogeneous magnetic field for spin-flip detection)
Double-Trap Technique for g-Factor Measurements
Atomic Physics
-15 -10 -5 0 5 10 150
10
20
30
40 C5+
Frequency ratio L/
c in rel. units [10-9]
Sp
in-f
lip p
rob
abili
ty [
% ]
• Measurement of the g-factor of the bound electron with an accuracy of 7 x 10-10
• Measurement of the g-factor of the bound electron with an accuracy of 7 x 10-10
G-Factor of bound electronin highly charged ions
Atomic Physics
Electron
(Van Dyck/
Dehmelt)
C5+
(Mainz/ GSI)
O7+
(Mainz/ GSI)
Antiproton
(proposed)
Magnetic moment
gB/2 gB/2 gB/2 gN/2
g-Factor g = 2.00... g = 2.00... g = 2.00... g = 5.58…
‘Magnetic
bottle‘
0.15 mT/mm2 10 mT/mm2 10 mT/mm2 230 mT/mm2
Dz due to
spinflip
1.3 Hz 0.7 Hz 0.46 Hz 0.25 Hz
Parameters of g-factor experiments
Atomic Physics
Improvement of accuracy in gpbar by six orders of magnitude Improvement of accuracy in gpbar by six orders of magnitude
Conclusions
Important test of CPT invariance for baryons Important test of CPT invariance for baryons
• Measurement of the magnetic moment of the bound electron with an accuracy of 7 x 10-10.• This experimental technique can be employed for the measurement of the magnetic moment of the antiproton.
• Measurement of the magnetic moment of the bound electron with an accuracy of 7 x 10-10.• This experimental technique can be employed for the measurement of the magnetic moment of the antiproton.