Peter Shawhan

Peter S. Shawhan
Associate Professor of Physics
The University of Maryland

pshawhan @
Office: Physical Sciences Complex (PSC), room 2120
Mailing address: PSC room 2120
4296 Stadium Drive
College Park, MD 20742-2440
(301) 405 1580

Peter Shawhan Peter Shawhan

My Research

LIGO logoI 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.  In particular, the Advanced LIGO upgrade, completed in 2015, finally enabled the direct detection of gravitational waves!  The first detection, a remarkably clear signal from the merger of two black holes into a single, more massive black hole, was recorded by the LIGO detectors on September 14, 2015, and announced to the world on February 11, 2016.  I have set up a GW150914 Resource Page with links to find out more information about the discovery and its meaning. We expect to detect and announce an increasing number of gravitational wave signals over the next several years.  One of the main research goals of my group at Maryland is to do "multi-messenger astronomy" by working with astronomers to find other signatures of gravitational-wave events.  We already got a good start on that with GW150914 (preprint of our paper).

LSC logoWhereas 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 maintain (though some of the links are restricted to collaboration members). I served for several years as Co-Chair of the LSC Burst Analysis Working Group. I have also been a member of the LSC Executive Committee, served on the LIGO Program Advisory Committee (PAC), and co-chaired the LIGO Academic Affairs Council (LAAC).

I am grateful to the National Science Foundation for financial support of my research through grants PHY-0653421, PHY-0738032, PHY-0757957, PHY-1068549 and PHY-1404121, as well as for the overall funding of the LIGO program.

My Ph.D. Thesis Research (1991-1999)

KTeV logo 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.)