Atomic structure measurements and tests of fundamental physics

in thallium and other heavy atoms



  • Group photo, March 2007 (L-R: Dr. Mevan Gunawardena (postdoc); Toby Scheider '07 (MIT/Woods Hole, Ocean Eng.); Jared Strait '07 (Cornell, E.E.); Owen Simpson '07 (Princeton, Physics) )



  • Development of differential phase shift technique using dual-direction optical ring cavity in atomic beam chamber


  • Blue/UV diode laser spectroscopy of thallium and indium at 378 nm and 410 nm respectively
    • both atoms have second-step transition resonant with available 1280-1300 nm diode laser
    • pursuing two-step, Doppler-narrowed spectroscopy and Stark shift measurements in both species


  • Historical group pictures
    • summer 2003 (L-R: Chris Holmes '03 (Harvard, Atmos. Sci.); Dr. Michael Green (U. Sydney, medical phys.); Colin Bruzewicz '05 (Yale, Physics); PKM; John BackusMayes (U. Wash., Physics); Mark Burkhardt '04 (Stanford, Physics).
    • summer 2004 (L-R: Dr. Ralph Uhl (Berlin); Mark Burkhardt '04; Joe Kerckhoff '05 (Caltech, Physics); Colin Bruzewicz '05; PKM)
    • summer 2005 (L-R (front): David Butts '06 (MIT, Aero. Eng.); Margaret Pigman '07; Daniel Sussman '07, Joe Kerckhoff '05)
    • with old friends Peter Nicholas '98 and Leo Tsai '98 (fall '05 joint colloquium on their MRI research)


    Slightly Older NEWS:
  • ICAP XVIII Poster Session (7/30/02) (Charlie Doret '02, Andrew Speck '00, Leo Tsai '98)
  • Views of our lab circa 2002:

The folks who did so much of the work:

THESIS STUDENTS (list w/thesis titles and current activities ...)

Dr. David Richardson (postdoc: 12/98 - 6/01) [now at NW Missouri St. Univ.]

Dr. Michael Green (postdoc: 11/02 - 11/03) [now at U. Sidney / Medical Physics Imaging lab]

Dr. Ralph Uhl (postdoc: 1/04 - 12/05) [now in Berlin, Germany]

Dr. Mevan Gunawardena (current postdoc: 12/06 - ) [Ph.D., Purdue Univ. 2007]


A recent high-precision measurement (see pub #4 below) of atomic parity nonconservation (PNC) in atomic thallium (energy level diagram) has made possible a new low-energy test of the Standard Electroweak Model. A new (2001) calculation of Tl atomic puts the theoretical wavefunction error at 2.5%. In order to test the accuracy of current calculations and guide future refinement, we are undertaking a series of new measurements of (electromagnetic) atomic structure in thallium to provide independent, highly-precise tests of the atomic theory.

Our newest project involves a speculative search for evidence of Time reversal-violating (but Parity-conserving) forces in thallium using an optical ring-enhancement cavity and our thallium atomic beam apparatus. Recent development work for this experiment includes demonstration of thousand-fold common noise subtraction between counterpropagating beams in the ring cavity, as well as a new diode laser stabilization scheme using low-field magneto optics (laser locking to 0.5 MHz now demonstrated).

All of the measurements underway or presently planned make use of two major pieces of apparatus:

1. a vapor cell laser polarimeter capable of creating very dense samples of thallium (useful for studying forbidden transitions) and capable of very high resolution laser transmission and optical rotation measurements.

2. An atomic beam apparatus useful for creating Doppler-narrowed atomic samples in the presence of very large static electric fields for Stark effect measurements.

We acknowledge the generous support of :

Research Corporation (1994-1997)
NSF-RUI Program: (grant nos: 9721403; 0140189; 0555552)
NIST Precision Measurement Grant Program (1999-2002)
Williams College

Here are some older talks...

PKM talks:
Background and 378 nm experiments in thallium (April '03)
Ongoing 1283 nm experiments in thallium (April '03)

Talk by S. Charles Doret '02:

Apker Award Finalist Talk (APS Headquarters, Sept '02) [2.0 MB]

Some more words/pictures about past and current experiments...

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