A New Precise Measurement of the Stark Shift in the 6P1/2...
Transcript of A New Precise Measurement of the Stark Shift in the 6P1/2...
![Page 1: A New Precise Measurement of the Stark Shift in the 6P1/2 …web.williams.edu/wp-etc/physics/pmajumder/ApkerTalk.pdf · 2011-04-01 · A New Precise Measurement of the Stark Shift](https://reader030.fdocument.pub/reader030/viewer/2022040112/5e714232427ca13d3c465be5/html5/thumbnails/1.jpg)
A New Precise Measurement of the StarkShift in the 6P1/2->7S1/2 378 nm Transition in
Thallium
Apker Award Finalist Talk
September 4, 2002
S. Charles Doret
Earlier work by Andrew Speck Williams ’00, Paul Friedberg ’01,D.S. Richardson, PhD
![Page 2: A New Precise Measurement of the Stark Shift in the 6P1/2 …web.williams.edu/wp-etc/physics/pmajumder/ApkerTalk.pdf · 2011-04-01 · A New Precise Measurement of the Stark Shift](https://reader030.fdocument.pub/reader030/viewer/2022040112/5e714232427ca13d3c465be5/html5/thumbnails/2.jpg)
Summary of Tl Stark Shift Measurements
Our Measurement: ∆νStark = 103.23(39) kHz/(kV/cm)2
WStark = - _ αoE2 ; ∆νStark= -1/2h [αo(7S1/2) - αo(6P1/2)] E2
(αo is scalar polarizability; α2 = 0 for J= _ -> J= _)
[Fow70]
[DeM94]
PresentMeasurement
∆νStark (kHz/(kV/cm)2)
![Page 3: A New Precise Measurement of the Stark Shift in the 6P1/2 …web.williams.edu/wp-etc/physics/pmajumder/ApkerTalk.pdf · 2011-04-01 · A New Precise Measurement of the Stark Shift](https://reader030.fdocument.pub/reader030/viewer/2022040112/5e714232427ca13d3c465be5/html5/thumbnails/3.jpg)
- Worked on vacuum and laser frequency stabilization systems
- Rebuilt entire optical system for improved laser power and greaterstability
- Planned and implemented two data collection schemes, including software
- Built chopping system for improved signal-to-noise and reduced statisticalerror, including mechanical components, electronics, and software
- Collected and analyzed all data, including an exhaustive search forpotential remaining systematic effects
- Co-authored formal paper:
Measurement of the Stark shift within the 6P1/2 -> 7S1/2 378-nmtransition in atomic thallium, Doret et al. (To appear in Phys. Rev. A)
Key Contributions
![Page 4: A New Precise Measurement of the Stark Shift in the 6P1/2 …web.williams.edu/wp-etc/physics/pmajumder/ApkerTalk.pdf · 2011-04-01 · A New Precise Measurement of the Stark Shift](https://reader030.fdocument.pub/reader030/viewer/2022040112/5e714232427ca13d3c465be5/html5/thumbnails/4.jpg)
Motivation –Tests of Standard Electroweak Model with Atoms
- Atomic Parity Non-conservation measurements give both evidencefor and tests of fundamental physics
- Of interest here: Qw , predicted by elementary particle theory
According to Atomic Physics:
EPNC = Qw * C(Z)Group Element Experimental
Precision Atomic Theory
Precision Oxford '91 Bismuth 2% 8%
UW '93 Lead 1.2% 8% UW '95 Thallium 1.2% 2.5% (new, 2001)
Colorado '97 Cesium 0.35% ~ 1% (or less)
- Precision matters: { > 5% - not so interesting< 1% - very important
- Independent tests of atomic theory – separate from PNCmeasurements
- Improve on existing limits beyond the Standard Model
![Page 5: A New Precise Measurement of the Stark Shift in the 6P1/2 …web.williams.edu/wp-etc/physics/pmajumder/ApkerTalk.pdf · 2011-04-01 · A New Precise Measurement of the Stark Shift](https://reader030.fdocument.pub/reader030/viewer/2022040112/5e714232427ca13d3c465be5/html5/thumbnails/5.jpg)
How to measure?
2nd order Perturbation Theory:
∆νStark ∝ E2
-Proportionality constant based onan infinite sum of E1 matrixelements, similar to C(Z)
Electric Field Plate
CollimatedAtomic Beam
Transverse LaserProbe
Interaction Region: ?E 0
![Page 6: A New Precise Measurement of the Stark Shift in the 6P1/2 …web.williams.edu/wp-etc/physics/pmajumder/ApkerTalk.pdf · 2011-04-01 · A New Precise Measurement of the Stark Shift](https://reader030.fdocument.pub/reader030/viewer/2022040112/5e714232427ca13d3c465be5/html5/thumbnails/6.jpg)
AOM λ/4
wavemeter
Locking system
external cavity diode laser
755 nm, ~12 mW
opticalisolator PBS
RF frequencysynthesizer
(90-120 MHz)
external resonantfrequency-doubling (‘bowtie’ cavity)
To Lock-ins
PMT 2
PMT 1
collimatorschoppingwheel Tl oven
high-vacuum
ATOMIC BEAM
378 nm, ~0.5 µWchopping wheel
E-field plates
Atomic Beam and Optical System Layout
![Page 7: A New Precise Measurement of the Stark Shift in the 6P1/2 …web.williams.edu/wp-etc/physics/pmajumder/ApkerTalk.pdf · 2011-04-01 · A New Precise Measurement of the Stark Shift](https://reader030.fdocument.pub/reader030/viewer/2022040112/5e714232427ca13d3c465be5/html5/thumbnails/7.jpg)
Locking System:
ρ = b/a
Cavity length
Frequency Stabilization:
Frequency Tuning:
- Adjust 0 < ρ < 1 ~ 800 MHz range
- requires precise calibration of free spectral range; tuning is SLOW, manual
n λHeNe / 4 (n+1) λHeNe / 4m λdiode / 4
0 < ρ < 1
0 < ν < 838.2 MHz
![Page 8: A New Precise Measurement of the Stark Shift in the 6P1/2 …web.williams.edu/wp-etc/physics/pmajumder/ApkerTalk.pdf · 2011-04-01 · A New Precise Measurement of the Stark Shift](https://reader030.fdocument.pub/reader030/viewer/2022040112/5e714232427ca13d3c465be5/html5/thumbnails/8.jpg)
AOM λ/4
wavemeter
Locking system
external cavity diode laser
755 nm, ~12 mW
opticalisolator PBS
RF frequencysynthesizer
(90-120 MHz)
external resonantfrequency-doubling (‘bowtie’ cavity)
f0+νAOM
(νAOM)
f 0+2
ν AO
Mf0
2f0+4νAOMTo Lock-ins
PMT 2
PMT 1
collimatorschoppingwheel Tl oven
high-vacuum
ATOMIC BEAM
378 nm, ~0.5 µWchopping wheel
E-field plates
Atomic Beam and Optical System Layout
![Page 9: A New Precise Measurement of the Stark Shift in the 6P1/2 …web.williams.edu/wp-etc/physics/pmajumder/ApkerTalk.pdf · 2011-04-01 · A New Precise Measurement of the Stark Shift](https://reader030.fdocument.pub/reader030/viewer/2022040112/5e714232427ca13d3c465be5/html5/thumbnails/9.jpg)
Optical Table
Interaction Region
Doubling Cavity
![Page 10: A New Precise Measurement of the Stark Shift in the 6P1/2 …web.williams.edu/wp-etc/physics/pmajumder/ApkerTalk.pdf · 2011-04-01 · A New Precise Measurement of the Stark Shift](https://reader030.fdocument.pub/reader030/viewer/2022040112/5e714232427ca13d3c465be5/html5/thumbnails/10.jpg)
30 cm
steppermotor
block/unblockatoms @ 1 Hz
Top View:(vTrans ~ vLong / 16)
plate sep: 1.0002(2) cm
voltage divider(10-4 precision)
± 30 kV
750 C10-7 torr
Atomic Beamline
![Page 11: A New Precise Measurement of the Stark Shift in the 6P1/2 …web.williams.edu/wp-etc/physics/pmajumder/ApkerTalk.pdf · 2011-04-01 · A New Precise Measurement of the Stark Shift](https://reader030.fdocument.pub/reader030/viewer/2022040112/5e714232427ca13d3c465be5/html5/thumbnails/11.jpg)
Data Collection/Signal Processing
Chopping System:
- Laser Beam chopping rejects any noise with frequencycomponents other than the modulation frequency – 1400 Hz
- Atomic Beam chopping to correct for optical table drifts,beam density fluctuations, etc. – 1Hz
Division/Subtraction Schemes:
- Extra PMT for laser beam intensity normalization
- Interested in difference signals A-B:
- Collect data in ABBA format to minimize the effects of lineardrifts
offAtoms
E-field
on on ononoff off off
off onA B
![Page 12: A New Precise Measurement of the Stark Shift in the 6P1/2 …web.williams.edu/wp-etc/physics/pmajumder/ApkerTalk.pdf · 2011-04-01 · A New Precise Measurement of the Stark Shift](https://reader030.fdocument.pub/reader030/viewer/2022040112/5e714232427ca13d3c465be5/html5/thumbnails/12.jpg)
T(ν) = exp[-βV(γ,Γ;ν)], V a normalized Voigt profile
(same for all 6 peaks in transition)
γ = 20 MHz
Γ = 100 MHz
β = 0.5
Transmission Profile
![Page 13: A New Precise Measurement of the Stark Shift in the 6P1/2 …web.williams.edu/wp-etc/physics/pmajumder/ApkerTalk.pdf · 2011-04-01 · A New Precise Measurement of the Stark Shift](https://reader030.fdocument.pub/reader030/viewer/2022040112/5e714232427ca13d3c465be5/html5/thumbnails/13.jpg)
∆S
Ε2
+–0
(1) Lock laser to inflection point of transmission curve (dip), measure S = T/N (E = 0)
(3) Repeat sequence with altered Electric field values, but same ∆f.
(2) - Turn on Electric field (E = E0) - Shift AOM frequency by appropriate amount (∆f); - Determine S’ and ∆S = S’ - S
∆f fixed
(4) Find y-intercept of linear fit -- value of E2 which exactly matches ∆f
Transmission Change:
![Page 14: A New Precise Measurement of the Stark Shift in the 6P1/2 …web.williams.edu/wp-etc/physics/pmajumder/ApkerTalk.pdf · 2011-04-01 · A New Precise Measurement of the Stark Shift](https://reader030.fdocument.pub/reader030/viewer/2022040112/5e714232427ca13d3c465be5/html5/thumbnails/14.jpg)
Statistical Analysis
Final Statistical Error: 0.20 kHz/(kV/cm)2 (0.19%)
Std. Error
![Page 15: A New Precise Measurement of the Stark Shift in the 6P1/2 …web.williams.edu/wp-etc/physics/pmajumder/ApkerTalk.pdf · 2011-04-01 · A New Precise Measurement of the Stark Shift](https://reader030.fdocument.pub/reader030/viewer/2022040112/5e714232427ca13d3c465be5/html5/thumbnails/15.jpg)
Systematic Error Analysis
Doppler Shifts:
δf = f∗ v/c
= 4*1014(300 m/s / 3*108 m/s) * 10-3 rad
= 0.4 MHz (0.38%)
4*1014(300 m/s / 3*108 m/s) * 10-4 rad
40 kHz (0.04 %)
≤
≤
![Page 16: A New Precise Measurement of the Stark Shift in the 6P1/2 …web.williams.edu/wp-etc/physics/pmajumder/ApkerTalk.pdf · 2011-04-01 · A New Precise Measurement of the Stark Shift](https://reader030.fdocument.pub/reader030/viewer/2022040112/5e714232427ca13d3c465be5/html5/thumbnails/16.jpg)
Correlation Plots
- Concerns about linear fit used to extract kStark with TransmissionChange method
Simulation: Measured:
- Symmetric data collection on both sides since opposite effect
inf. pt.wings peak
![Page 17: A New Precise Measurement of the Stark Shift in the 6P1/2 …web.williams.edu/wp-etc/physics/pmajumder/ApkerTalk.pdf · 2011-04-01 · A New Precise Measurement of the Stark Shift](https://reader030.fdocument.pub/reader030/viewer/2022040112/5e714232427ca13d3c465be5/html5/thumbnails/17.jpg)
∆νStark
(kHz/(kV/cm)2)Transmission Change
Analysis
103.39Final mean value
Systematic Error Sources:
0.20Statistical Error
0.43Quadrature Sum
0.01E-field calibration
0.16Residual Doppler Shift
0.30Curve linearity
0.01Hi/Lo side lock
0.04E2 Step size
0.26Oven Temperature
![Page 18: A New Precise Measurement of the Stark Shift in the 6P1/2 …web.williams.edu/wp-etc/physics/pmajumder/ApkerTalk.pdf · 2011-04-01 · A New Precise Measurement of the Stark Shift](https://reader030.fdocument.pub/reader030/viewer/2022040112/5e714232427ca13d3c465be5/html5/thumbnails/18.jpg)
- Sequentially lock the diode laser, calibrate “ρ”- Scan over single line of 205Tl. Fit data to Voigt transmission profile
∆νStark 2)/25(
63
cmkV
MHz=
= 101kHz/(kV/cm)2
“ρ” Frequency Scan:
![Page 19: A New Precise Measurement of the Stark Shift in the 6P1/2 …web.williams.edu/wp-etc/physics/pmajumder/ApkerTalk.pdf · 2011-04-01 · A New Precise Measurement of the Stark Shift](https://reader030.fdocument.pub/reader030/viewer/2022040112/5e714232427ca13d3c465be5/html5/thumbnails/19.jpg)
Some ρ Scan ErrorsFitting Errors:
Statistics:
∆νS
tark
kHz/
(kV
/cm
)2
![Page 20: A New Precise Measurement of the Stark Shift in the 6P1/2 …web.williams.edu/wp-etc/physics/pmajumder/ApkerTalk.pdf · 2011-04-01 · A New Precise Measurement of the Stark Shift](https://reader030.fdocument.pub/reader030/viewer/2022040112/5e714232427ca13d3c465be5/html5/thumbnails/20.jpg)
ConclusionsFrequency Scan: -103.02(62) kHz/(kV/cm)2 Transmission Change: -103.39(43) kHz/(kV/cm)2
Combined Value: 103.23(39) kHz/(kV/cm)2
Theory %Error
- Factor of 15 improvement over previous measurement
- [αo(7S1/2) - αo(6P1/2)] = 122.96(47) x 10-24 cm3
[Fow70]
[DeM94]
PresentMeasurement
∆νStark (kHz/(kV/cm)2)