Edward M. Mattison

Limit on Lorentz and CPT violation of the proton using a hydrogen maser

We present a new measurement constraining Lorentz and

Testing CPT and Lorentz symmetry with hydrogen masers

\mathrm{CPT}

New clock comparison searches for Lorentz and CPT violation

violation of the proton using a hydrogen maser double resonance technique. A search for hydrogen Zeeman frequency variations with a period of the sidereal day (23.93 h) sets a limit on violation of Lorentz and

Fifteen years of Chandra operation: scientific highlights and lessons learned

\mathrm{CPT}

Ultra stable clocks for use in space

symmetry of the proton at the

A hydrogen maser at temperatures below 1 K

{10}^{\ensuremath{-}27}

The Cold Hydrogen Maser

GeV level, independent of nuclear model uncertainty, which improves significantly on previous bounds.

A Hydrogen Maser at Temperatures Below 1k

In a recent paper [Phys. Rev. D 63, 111101 (2001)] we reported a new limit on CPT (charge, parity, and time reversal) and Lorentz violation of the proton by using a hydrogen maser to search for a sidereal variation of the F=1, {delta}m{sub F}={+-}1 Zeeman frequency in atomic hydrogen. Here we discuss the theoretical interpretation of this recent experiment, the operating principles of the maser, and the double-resonance technique used to measure the Zeeman frequency. We also describe the characterization of systematic effects and details of the data analysis. We conclude by comparing our result to other recent experiments, and discussing potential improvements to the hydrogen maser double-resonance technique.

The Chandra X-ray Center: a combined science and operations center

We present two new measurements constraining Lorentz and CPT violation using the 129Xe/3He Zeeman maser and atomic hydrogen masers. Experimental investigations of Lorentz and CPT symmetry provide important tests of the framework of the standard model of particle physics and theories of gravity. The two-species 129Xe/3He Zeeman maser bounds violations of CPT and Lorentz symmetry of the neutron at the 10−31 GeV level. Measurements with atomic hydrogen masers provide a clean limit of CPT and Lorentz symmetry violation of the proton at the 10−27 GeV level.

A hydrogen maser for long-term operation in space

NASAs Chandra X-Ray Observatory, designed for three years of operation with a goal of five years, is now entering its 15-th year of operation. Thanks to its superb angular resolution, the Observatory continues to yield new and exciting results, many of which were totally unanticipated prior to launch. We discuss the current technical status, review some recent scientific highlights, indicate a few future directions, and present what we are the most important lessons learned from our experience of building and operating this great observatory.