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Peter
S. Shawhan
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I am working on a major project
called LIGO (short for
Laser Interferometer Gravitational-wave
Observatory) which is designed to detect gravitational waves coming
from distant astrophysical objects such as black holes, neutron stars,
cosmic strings, or the core of a massive star when it collapses and
creates a supernova. Gravitational waves are distortions in the
geometry of space-time which are predicted, by Einstein's general
theory of relativity, to be emitted when massive bodies change their
shape or orientation rapidly. Direct searches for gravitational
waves began with Joe Weber here at the University of Maryland in the
1960s and have continued with increasingly sensitive detectors, but the
expected distortions are incredibly
tiny when they reach the Earth, and consequently have not yet been
directly detected. Technological advancements over the years have
finally made it feasible to construct detectors based on very large
laser interferometers, and after many years of design, construction,
and commissioning, LIGO and a few similar detectors (GEO, VIRGO) are
listening for gravitational waves with sensitivities which may allow us
to finally detect them in the not-too-distant future.
Whereas the construction and
operation of the LIGO observatories are co-led by Caltech (where I
spent 7 years as a postdoctoral fellow and staff scientist) and MIT,
the scientific mission of LIGO is carried out by the LIGO Scientific Collaboration, which
includes scientists at the University of Maryland along with a few
dozen other institutions. You can get an overview of many of the
scientific activities by visiting the LIGO Science Links web page. I
currently serve as Co-Chair of the LSC Burst
Analysis Working Group as well as Chair of the LSC internal review
committee for the Periodic
Sources
Working Group.
As a graduate student at the
University of Chicago, I worked on a particle
physics experiment called KTeV which
studied the decays of neutral K mesons produced in a fixed-target beam
at Fermilab. The neutral K
meson system is remarkable in that two
neutral K meson states are
observed, one of which lives (on average) about 580 times longer than
the other before it decays. This is the result of mixing of
the quantum eigenstates due to particle interactions, and it turns out
that
there is a small particle-antiparticle asymmetry in the mixing,
referred to as "CP violation". One of the main goals of KTeV was
to measure an even more subtle effect, direct CP violation in the decay
process itself, by comparing
the decays of the short- and long-lived K mesons. My thesis
research was the measurement of direct CP violation using the first
part of the data collected by KTeV; we found a clear nonzero effect,
and published the results in Phys. Rev. Lett.
83, 22 (1999). (For anyone who may be
interested, my Ph.D. thesis is available in PostScript
or PDF format.)