Michael L. Cherry, Ph.D.
Michael L. Cherry, PhD
Roy P. Daniels Professor of Physics
Ph.D., 1978 - University of Chicago
Louisiana State University
Department of Physics & Astronomy
202-K Nicholson Hall, Tower Dr.
Baton Rouge, LA 70803-4001
Space Science/High Energy Astrophysics
High energy astrophysics deals with the radiation produced by energetic particles in space, their astrophysical sources, and the acceleration mechanisms that produce the very high energy particles. We observe cosmic ray protons and nuclei at earth with energies orders of magnitude higher than the proton rest mass. Our previous JACEE balloon measurements show no evidence for the expected drop-off in the proton-helium spectra due to acceleration by supernova shocks. The ATIC collaboration, in addition to measuring elemental spectra, reported an anomalous enhancement in the electron flux below a TeV. Our LSU group is now involved in the operation of the CALET (CALorimetric Electron Telescope) experiment on the International Space Station, beginning a 5-year mission in 2015 to provide a definitive measurement of the high energy electron spectrum.
Since charged cosmic ray particles are randomized in direction by the galaxy's magnetic field, however, they do not come in straight lines from their sources. Hard x-rays and gamma rays (10 keV - 40 MeV) provide direct information about the high energy sources. The Gamma ray Burst Monitor (GBM) on the Fermi satellite is being used to monitor the hard x-ray sky, and has detected an unexpected decrease in the flux from the Crab Nebula. Our group is involved in analyzing the GBM and earlier CGRO/BATSE earth occultation data. GBM has observed flaring activity from the blazars M421 and M501, Sco X-1, Cygnus X-1, and the transient X-ray pulsar system V0332+53.
We are operating a ground-based array that has detected Terrestrial Gamma ray Flashes (TGFs), bursts of gamma rays associated with nearby lightning storms, and plan to install two more sensitive arrays in Puerto Rico and Jamaica by early 2016, in locations where the lightning intensity is a good deal higher than in Louisiana.
Finally, we are developing the transition radiation detectors to be used to identify protons, kaons, and pions at TeV energies for a proposed CERN experiment to measure high energy cross sections in the far forward region.
Current and Selected Publications
"First Results from Fermi GBM Earth Occultation Monitoring: Observations of Soft Gamma-Ray Sources Above 100 keV", G.L. Case et al., Astrophysical J. 729, 105 (2011); PDF.
- “When A Standard Candle Flickers”, C.A. Wilson-Hodge et al., Astrophysical J. Letters 727, L40 (2011); PDF.
- “Characteristic Count Rate Profiles for a Rotating Modulator Gamma-Ray Imager”, B.S. Budden et al., Astrophys. and Space Sci. 334, 61 (2011); PDF.
- “Three years of Fermi GBM Earth Occultation Monitoring: Observations of Hard X-ray/Soft Gamma-Ray Sources”, C.A. Wilson-Hodge et al., Astrophysical J. Suppl. 201, 33 (2012); Article.
- “CALET: A Calorimeter-based Orbital Observatory for High Energy Astroparticle Physics”, P.S. Marrocchesi for the CALET Collaboration, Nucl. Instrum. Meth. in Phys. Res. A, 692, 240 (2012); Article.
- “Next Steps in Measurements of Cosmic Ray Electrons, M.L. Cherry, AIP Conf. Proc. 1516, Centenary Symposium 2012: Discovery of Cosmic Rays, ed. J. Ormes, 269 (2013); doi:Article.
- “Measuring the Lorentz Factors of Energetic Particles with Transition Radiation”, M.L. Cherry, Nucl. Instrum. Meth. in Phys. Res. A 706, 39 (2013); Article.
- “Observation of Gamma Rays at Ground Level Associated with Nearby Thunderstorms", R. Ringuette et al., J. Geophysical Res: Space Phys. 118, 7841 (2013).Article.
- “Kepler K2 Observations of Sco X-1: Orbital Modulations and Correlations with Fermi GBM and MAXI", R.I. Hynes et al., submitted (2015).