Probing the electron edm with cold molecules E.A. Hinds Columbus Ohio, 23 June, 2010 Centre for Cold...
-
Upload
melissa-hoover -
Category
Documents
-
view
214 -
download
0
Transcript of Probing the electron edm with cold molecules E.A. Hinds Columbus Ohio, 23 June, 2010 Centre for Cold...
![Page 1: Probing the electron edm with cold molecules E.A. Hinds Columbus Ohio, 23 June, 2010 Centre for Cold Matter Imperial College London.](https://reader038.fdocuments.in/reader038/viewer/2022110213/56649eaa5503460f94baf0f8/html5/thumbnails/1.jpg)
Probing the electron edm with cold molecules
E.A. Hinds
Columbus Ohio, 23 June, 2010
Centre for Cold MatterImperial College London
![Page 2: Probing the electron edm with cold molecules E.A. Hinds Columbus Ohio, 23 June, 2010 Centre for Cold Matter Imperial College London.](https://reader038.fdocuments.in/reader038/viewer/2022110213/56649eaa5503460f94baf0f8/html5/thumbnails/2.jpg)
+ +
++
polarisable vacuum with increasinglyrich structure at shorter distances:
(anti)leptons, (anti)quarks, Higgs (standard model)beyond that: supersymmetric particles ………?
How an electron gets structure
-
point electron
![Page 3: Probing the electron edm with cold molecules E.A. Hinds Columbus Ohio, 23 June, 2010 Centre for Cold Matter Imperial College London.](https://reader038.fdocuments.in/reader038/viewer/2022110213/56649eaa5503460f94baf0f8/html5/thumbnails/3.jpg)
electronspin
+-edm
Electric dipole moment (EDM)
![Page 4: Probing the electron edm with cold molecules E.A. Hinds Columbus Ohio, 23 June, 2010 Centre for Cold Matter Imperial College London.](https://reader038.fdocuments.in/reader038/viewer/2022110213/56649eaa5503460f94baf0f8/html5/thumbnails/4.jpg)
Left -Right
MSSM f ~ /a p
Multi Higgs
MSSM
f ~ 1
10-24
10-22
10-26
10-28
10-30
10-32
10-34
10-36
eEDM (e.cm)
Our experiment on YbF molecules
explores this region
Standard Model
de < 1.6 x 10-27 e.cm
Commins (2002)
Excluded region (Tl atomic beam)
10-18 Deb.
![Page 5: Probing the electron edm with cold molecules E.A. Hinds Columbus Ohio, 23 June, 2010 Centre for Cold Matter Imperial College London.](https://reader038.fdocuments.in/reader038/viewer/2022110213/56649eaa5503460f94baf0f8/html5/thumbnails/5.jpg)
The magnetic moment problem
Suppose de = 5 x 10-28 e.cm(the region we explore)
In a field of 10kV/cm de.E _ 1 nHz ~
When does mB.B equal this ?
B _ 1 fG~
It seems impossible to control B at this levelespecially when applying a large E field
![Page 6: Probing the electron edm with cold molecules E.A. Hinds Columbus Ohio, 23 June, 2010 Centre for Cold Matter Imperial College London.](https://reader038.fdocuments.in/reader038/viewer/2022110213/56649eaa5503460f94baf0f8/html5/thumbnails/6.jpg)
A clever solution
E
electric field
de
amplification
atom or molecule containing electron
(Sandars)
For more details, see E. A. H. Physica Scripta T70, 34 (1997)
Interaction energy
-de E•
F PPolarization factor
Structure-dependent
relativistic factor ~ 10 (Z/80)3 GV/cm
![Page 7: Probing the electron edm with cold molecules E.A. Hinds Columbus Ohio, 23 June, 2010 Centre for Cold Matter Imperial College London.](https://reader038.fdocuments.in/reader038/viewer/2022110213/56649eaa5503460f94baf0f8/html5/thumbnails/7.jpg)
Our experiment uses a molecule – YbF
EDM interaction energy is a million times larger (mHz)
mHz energy now “only” requires nG stray field control
0
5
10
15
20
0 10 20 30
Applied field E (kV/cm)
Eff
ecti
ve f
ield
E
(G
V/c
m)
Amplification in YbF
16 GV/cm
![Page 8: Probing the electron edm with cold molecules E.A. Hinds Columbus Ohio, 23 June, 2010 Centre for Cold Matter Imperial College London.](https://reader038.fdocuments.in/reader038/viewer/2022110213/56649eaa5503460f94baf0f8/html5/thumbnails/8.jpg)
| -1 > | +1 >
| 0 >
The lowest two levels of YbF
Goal: measure the splitting 2dehE to ~1mHz
F=1
F=0
E
-dehE
+dehE
+-
+-
X2S+ (N = 0,v = 0)
170 MHz
![Page 9: Probing the electron edm with cold molecules E.A. Hinds Columbus Ohio, 23 June, 2010 Centre for Cold Matter Imperial College London.](https://reader038.fdocuments.in/reader038/viewer/2022110213/56649eaa5503460f94baf0f8/html5/thumbnails/9.jpg)
Flu
ores
cenc
e
Time of flight (ms)
Time-of-flight profile
2.1 2.3 2.5 2.7 2.9 3.1
How it is done
Pulsed YbF beam
PumpA-X Q(0) F=1
ProbeA-X Q(0) F=1
PMT
3K beam
F=1
F=0
rf pulseB HV+
HV-
Scanning the B-field
-200 -100 100 200 B (nT)
Ch 15 Cold Molecules, eds. Krems, Stwalley and Friedrich, (CRC Press 2009)
![Page 10: Probing the electron edm with cold molecules E.A. Hinds Columbus Ohio, 23 June, 2010 Centre for Cold Matter Imperial College London.](https://reader038.fdocuments.in/reader038/viewer/2022110213/56649eaa5503460f94baf0f8/html5/thumbnails/10.jpg)
Measuring the edm
Applied magnetic field
Det
ecto
r co
un
t ra
te
B0
-EE
Interferometer phase f = 2(mB + dehE)t/hInterferometer phase f = 2(mB)t/h-
de
-B0
![Page 11: Probing the electron edm with cold molecules E.A. Hinds Columbus Ohio, 23 June, 2010 Centre for Cold Matter Imperial College London.](https://reader038.fdocuments.in/reader038/viewer/2022110213/56649eaa5503460f94baf0f8/html5/thumbnails/11.jpg)
Modulate everything
• Generalisation of phase-sensitive
detection
• Switch periodically on short timescale
but randomly on long timescale.
• Sequence chosen to minimize noise.
• Measure all 512 correlations.
±E±B
±B
±rf2f±rf1f
±rf2a±rf1a
±laser f±rf
spin interferometer signal
9 switches:
512 possible correlations
![Page 12: Probing the electron edm with cold molecules E.A. Hinds Columbus Ohio, 23 June, 2010 Centre for Cold Matter Imperial College London.](https://reader038.fdocuments.in/reader038/viewer/2022110213/56649eaa5503460f94baf0f8/html5/thumbnails/12.jpg)
7 Non-zero correlations
• 504 correlations should be zero and they are!
correlation mean s mean/s fringe slope calibration beam intensity f-switch changes rf amplitude E drift
E asymmetry E asymmetry inexact π pulse
• We don’t look at the last one (EDM).
![Page 13: Probing the electron edm with cold molecules E.A. Hinds Columbus Ohio, 23 June, 2010 Centre for Cold Matter Imperial College London.](https://reader038.fdocuments.in/reader038/viewer/2022110213/56649eaa5503460f94baf0f8/html5/thumbnails/13.jpg)
** Don’t look at the mean edm **
• We don’t know what result to expect.
• Still, to avoid inadvert bias we hide the mean edm.
• A random blind offset is added that only the computer knows.
• More important than you might think.– e.g. Jeng, Am. J. Phys. 74 (7), 2006.
![Page 14: Probing the electron edm with cold molecules E.A. Hinds Columbus Ohio, 23 June, 2010 Centre for Cold Matter Imperial College London.](https://reader038.fdocuments.in/reader038/viewer/2022110213/56649eaa5503460f94baf0f8/html5/thumbnails/14.jpg)
+20
-20
mean
ED
M (
10
-26 e
.cm
)7381 measurements (~6 min each) at 11.6
kV/cm.
+40
-40
mean
ED
M (
10
-26 e
.cm
)
1440 measurements (~6 min each) at 3.3 kV/cm
![Page 15: Probing the electron edm with cold molecules E.A. Hinds Columbus Ohio, 23 June, 2010 Centre for Cold Matter Imperial College London.](https://reader038.fdocuments.in/reader038/viewer/2022110213/56649eaa5503460f94baf0f8/html5/thumbnails/15.jpg)
Initial edm results and std. error
-147± 5 ×10-28 e.cm
mean-10 10 (10-26 e.cm)
edm distribution
11.6 kV/cmBlind results
includes blind offset
mean-20 20 (10-26 e.cm)
edm distribution
3.3 kV/cm-144±22 ×10-28 e.cm
with same offset
![Page 16: Probing the electron edm with cold molecules E.A. Hinds Columbus Ohio, 23 June, 2010 Centre for Cold Matter Imperial College London.](https://reader038.fdocuments.in/reader038/viewer/2022110213/56649eaa5503460f94baf0f8/html5/thumbnails/16.jpg)
Two systematic error corrections
• Magnetic field noise B fluctuations synchronous with E reversal
produce false EDM.
We measure and correct: (-2.2 ± 1.6) ×10-28 e.cm.
• Electric field asymmetry “Reversal” changes magnitude of E (slightly)
This induces a false EDM We measure and correct: (+0.4 ± 0.4) ×10-28
e.cm.
![Page 17: Probing the electron edm with cold molecules E.A. Hinds Columbus Ohio, 23 June, 2010 Centre for Cold Matter Imperial College London.](https://reader038.fdocuments.in/reader038/viewer/2022110213/56649eaa5503460f94baf0f8/html5/thumbnails/17.jpg)
Negligible systematics
• HV charging current: can magnetize shields
< 0.3 ×10-28 e.cm B that reverses with E
•B. E. Sauer, Dhiren Kara, J. J. Hudson, M. R. Tarbutt, E. A. Hinds “A robust floating nanoammeter”. Rev. Sci. Instr. 79, 126102 (2008).
• HV leakage current: makes B that reverses with E i < 2 nA < 0.8 ×10-28 e.cm
“A robust floating nanoammeter” Rev. Sci. Instr. 79, 126102 (2008).Faraday Discussions, 142, 37 (2009)
• Changing E direction along beamline
< 0.03 ×10-28 e.cm
geometric phase
![Page 18: Probing the electron edm with cold molecules E.A. Hinds Columbus Ohio, 23 June, 2010 Centre for Cold Matter Imperial College London.](https://reader038.fdocuments.in/reader038/viewer/2022110213/56649eaa5503460f94baf0f8/html5/thumbnails/18.jpg)
F=0
F=1
sensitive to E (Stark shift)
Mapping the E field
3K beamrf pulse
B
170.9170.8170.7
Frequency (MHz)
020
4060
80100
0
100
200
300
400
500
600
Frequency
(M
Hz)
Molecule arrival time
PRA 76 033410 (2007)
Electric field variation along plates
Position along plates (m)
-0.75%
0
+0.75%
0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3 1.4
gap is constantto ± 90 μm !
![Page 19: Probing the electron edm with cold molecules E.A. Hinds Columbus Ohio, 23 June, 2010 Centre for Cold Matter Imperial College London.](https://reader038.fdocuments.in/reader038/viewer/2022110213/56649eaa5503460f94baf0f8/html5/thumbnails/19.jpg)
One last check...Identical run, but with E reversal
disabled
9000 edm measurements (3 months)
false edm < 4 ×10-28 e.cm
No systematics observed.
![Page 20: Probing the electron edm with cold molecules E.A. Hinds Columbus Ohio, 23 June, 2010 Centre for Cold Matter Imperial College London.](https://reader038.fdocuments.in/reader038/viewer/2022110213/56649eaa5503460f94baf0f8/html5/thumbnails/20.jpg)
80
60
40
200
-20ED
M (
10
-28 e
.cm
) NO! EDM changes across the
pulse
One last, last check!
PMT
Do front and back of pulsemeasure the same EDM?
![Page 21: Probing the electron edm with cold molecules E.A. Hinds Columbus Ohio, 23 June, 2010 Centre for Cold Matter Imperial College London.](https://reader038.fdocuments.in/reader038/viewer/2022110213/56649eaa5503460f94baf0f8/html5/thumbnails/21.jpg)
What’s going on ???The edm should not care where it is measured
(front or back of pulse)
The edm should not care how fast molecules are (570 or 590 m/s)
We find that this “chirp” is proportional to
(i) detuning of 1st rf pulse (ii) asymmetry of E reversal
Can be corrected, but we’d like a detailed model
![Page 22: Probing the electron edm with cold molecules E.A. Hinds Columbus Ohio, 23 June, 2010 Centre for Cold Matter Imperial College London.](https://reader038.fdocuments.in/reader038/viewer/2022110213/56649eaa5503460f94baf0f8/html5/thumbnails/22.jpg)
Current status
• Close to a measurement at the level of 4×10-28
e.cm
• Systematics seem under control at this level, but we’d like to understand the chirp.
• Expect to unveil the result later this summer
![Page 23: Probing the electron edm with cold molecules E.A. Hinds Columbus Ohio, 23 June, 2010 Centre for Cold Matter Imperial College London.](https://reader038.fdocuments.in/reader038/viewer/2022110213/56649eaa5503460f94baf0f8/html5/thumbnails/23.jpg)
New cryogenic buffer gas source of YbF
YbF beam
YAGablationlaser
3K He gas cell
Yb+AlF3
target
Spectroscopy inside: New J.Phys. 11, 123026 (2009)
![Page 24: Probing the electron edm with cold molecules E.A. Hinds Columbus Ohio, 23 June, 2010 Centre for Cold Matter Imperial College London.](https://reader038.fdocuments.in/reader038/viewer/2022110213/56649eaa5503460f94baf0f8/html5/thumbnails/24.jpg)
the real thing
upper LIFdetector
lower LIFdetector
YbF beam
![Page 25: Probing the electron edm with cold molecules E.A. Hinds Columbus Ohio, 23 June, 2010 Centre for Cold Matter Imperial College London.](https://reader038.fdocuments.in/reader038/viewer/2022110213/56649eaa5503460f94baf0f8/html5/thumbnails/25.jpg)
170MHz
Q(0) hyperfine splitting Lower PMTUpper PMT6
5
4
3
2
1
0
mol
ecul
es /s
r/pu
lse
(10
10) 170
Beam intensity
174Q(0)
170 MHz hfs
fluorescence spectrum
5 1010 molecules/sr/pulse in N=0 F=1 25 higher intensity than best previous!
relative frequency (MHz)
![Page 26: Probing the electron edm with cold molecules E.A. Hinds Columbus Ohio, 23 June, 2010 Centre for Cold Matter Imperial College London.](https://reader038.fdocuments.in/reader038/viewer/2022110213/56649eaa5503460f94baf0f8/html5/thumbnails/26.jpg)
Beam velocity
LIF at lower PMT z = 23mm
LIF at upper PMT z = 132mm
0 1 2 3 4 5 6time (ms)
v = 150 m/stuneable byHe pressure100-200 m/s
700 ms
700 ms
![Page 27: Probing the electron edm with cold molecules E.A. Hinds Columbus Ohio, 23 June, 2010 Centre for Cold Matter Imperial College London.](https://reader038.fdocuments.in/reader038/viewer/2022110213/56649eaa5503460f94baf0f8/html5/thumbnails/27.jpg)
EDM prospects with new source
25 more molecules
=> 20 better signal:noise ratio
Also, ideal source fordecelerating or trapping many species
and for laser cooling CaF, BaF, SrF to K.
4 longer interaction time
=> access to low 10-29 e.cm range!
![Page 28: Probing the electron edm with cold molecules E.A. Hinds Columbus Ohio, 23 June, 2010 Centre for Cold Matter Imperial College London.](https://reader038.fdocuments.in/reader038/viewer/2022110213/56649eaa5503460f94baf0f8/html5/thumbnails/28.jpg)
Acknowledgements
Royal Society EPSRC Euroquam CHIMONO
Ben SauerJony Hudson
Mike Tarbutt
Dhiren Kara (Ph..)
Joe Smallman (P...) EDM
Rich Hendricks
Sarah Skoff (Ph..)
Nick Bulleid (P...)
buffer gassource