John A. Poirier
Astrophysics and Elementary Particle Physics
B.S., University of Notre Dame, 1954
M.S., Stanford University, 1955
Ph.D., Stanford University, 1959
E-mail: poirier (at) nd (dot) edu
Address: Nieuwland Science Hall 204B
Phone: (574) 631-7588
Fax: (574) 631-5952
Prof. Poirier's doctoral thesis was supervised by W.K.H. Panofsky, "Positron electron scattering at 200 MeV," an elastic scattering experiment suggested by Burton Richter. It was the first such experiment conducted at Stanford’s HEPL prior to the construction of SLAC. The results agreed with Bhabha's theory and showed the necessity of the annihilation term among the Feynman graphs.
Poirier went on to study pion electron scattering at the Serpukhov high energy accelerator in Russia, the first such international collaboration between Russia and the United States which thus required approval by the U.S. Department of State. The experiment measured the radius of the pi-minus meson utilizing a 50 GeV negative pion beam at Serpukhov (at that time the highest energy accelerator in the world) and then later with a 100 GeV pion beam at the newly constructed higher energy accelerator at Fermilab.
At Notre Dame, Poirier is an astrophysicist studying cosmic rays operating an extensive air shower array utilizing position sensitive multiwire detectors. The 100m x 100m array is located just north of campus and is comprised of 64 detector stations. Each station has 8 proportional wire planes capable of measuring each track’s angle to 0.25 degrees in each of two orthogonal planes.
The cosmic ray array studies the properties of primary cosmic rays in the energy region above 10 billion, or 10 giga, electron Volts (GeV) using data from single track muon secondaries. The detector identifies each secondary track as a muon or an electron. By comparing the counting rate of muon secondaries with solar activity, a six sigma coincidence shows the sun is capable of accelerating protons to energies of >10 GeV. Ultra-high-energy cosmic rays, primary energies above 100 trillion electron volts (TeV), are studied simultaneously using the extensive air shower data of secondary electrons and muons in time coincidence with adjacent detector stations. The energy of the primary particle is obtained from the total number of detected secondary particles. Since gamma rays are undeflected as they travel through the magnetic fields of interstellar space, their primary angle pinpoints their stellar origin.
Interest in relativistic jets resulted in a first post-Newtonian calculation of a general relativistic effect that shows a non-utilized gravitomagnetic force due to moving masses is significant in the production of these jets in addition to the ordinary magnetic effects due to moving charges. This research is published in the last entry of the “Selected Publications" listed below.
“Ground level muons in coincidence with the solar flare of April 15, 2001,” J. Poirier and C. D’Andrea, J. Geophys. Res., Space Physics, Vol. 107(A11) 1376-1384 (2002).
“Search for sub-TeV gamma rays in coincidence with gamma ray bursts,” J. Poirier, C. D’Andrea, P.C. Fragile, J. Gress, G.J. Mathews, and D. Race, Phys. Rev. D 67, 042001, 1-6 (2003).
“Constraints on models for TeV gamma rays from gamma-ray bursts,” P.C. Fragile, G.J. Mathews, J. Poirier, T. Totani, Astroparticle Physics 20, 591-607 (2004).
“Ground level muons coincident with the 20 January 2005 solar flare,” C. D’Andrea and J. Poirier, Geophys. Res. Lett. 32, L14102 (2005).
"Experimental data and analysis of the October 2003 Forbush decrease," C.D'Andrea, J. Poirier, D.S. Balsara, Advances in Space Research 44, 1248-1251 (2009).
"Gravitomagnetic acceleration from black hole accretion disks," J. Poirier and G. J. Mathews, Classical and Quantum Gravity, 33, 107001 (2016).
Honors and Activities
Prof. Poirier has been an NSF postdoctoral fellow at CERN, Geneva, Switzerland; invited by the Nobel Committee for Physics on behalf of the Royal Swedish Academy of Sciences to submit proposals for Nobel prizes in Physics; the first Selected Publication (above) was selected by the Editors of the Journal of Geophysical Research as a Journal Highlight.