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 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 design of the CALET (CALorimetric Electron Telescope) experiment, designed to fly on the International Space Station 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.
We are operating a ground-based array looking for Terrestrial Gamma ray Flashes (TGFs), bursts of gamma rays associated with lightning storms, and plan to fly a balloon instrument near a thunderstorm to look for low intensity nearby TGFs from above. Finally, we have developed a new approach to high resolution gamma ray imaging based on rotational modulation with lanthanum bromide scintillators.
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.
- “X-Ray and Optical Observations of A0535+26”, A. Camero-Arranz et al., Astrophysical J. 754, 20 (2012); Article.
- “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.