Calvin R. Howell
Professor of Physics
Professor Howell’s research is in the area of experimental nuclear physics with emphasis on the quantum chromodynamics (QCD) description of low-energy nuclear phenomena, including structure properties of nucleons and nuclei and reaction dynamics in few-nucleon systems. The macroscopic properties of nucleon structure and the residual strong nuclear force between neutrons and protons in nuclei emerge from QCD at distances where the color interactions between quarks and gluons are strong. However, the details of the mechanisms that generate the strong nuclear force are not well understood. Effective field theories (EFT) and Lattice QCD calculations provide theoretical frames that connect low-energy nuclear phenomena to QCD. Professor Howell and collaborators are conducting experiments on few-nucleon systems that test predictions of ab-initio theory calculations for the purpose of providing insight about the QCD descriptions of low-energy nucleon interactions and structure. His current projects include measurements of the electromagnetic and spin-dependent structure properties of nucleons via Compton scattering on the proton and few-nucleon systems and studies of two- and three-nucleon interactions using few-nucleon reactions induced by photons and neutrons. In the coming years, a focus will be on investigating the neutron-neutron interaction in reactions and inside nuclei. In addition, his work includes applications of nuclear physics to national nuclear security, medical isotope production, and plant biology. Most of his research is carried out at the High Intensity Gamma-ray Source and the tandem laboratory at TUNL.
Xu, W., et al. “The Transverse Asymmetry A’T from Quasielastic Polarized Process and the Neutron Magnetic Form Factor.” Phys. Rev. Lett., vol. 85, 2000.
Jones, M. K., et al. “GEp/GMp Ratio form 0.5 to 3.5 GeV2 by Polarization Transfer in ep --> e'p.” Phys. Rev. Lett., vol. 84, 2000.
Schreiber, E. C., et al. “First Measurement of the Near-Threshold Analyzing Power Using a Free-Electron Laser Based g-Ray Source.” Phys. Rev. C, vol. 61, 2000.
Malov, S., et al. “Polarization transfer in the 16o(e→,e′p→)15n reaction.” Physical Review C Nuclear Physics, vol. 62, no. 5, 2000, pp. 573021–25.
Jones, M. K., et al. “GEp/GMp Ratio by Polarization Transfer in e→p → ep→.” Physical Review Letters, vol. 84, no. 7, 2000, pp. 1398–402.
Gao, J., et al. “Dynamical relativistic effects in quasielastic 1p-shell proton knockout from 16O.” Physical Review Letters, vol. 84, no. 15, Jan. 2000, pp. 3265–69. Scopus, doi:10.1103/PhysRevLett.84.3265. Full Text
Howell, C. R., et al. “Recent high-accuracy measurements of the S-1(0) neutron-neutron scattering length.” Few Body Problems in Physics ’99, edited by S. Oryu et al., vol. 12, SPRINGER-VERLAG WIEN, Jan. 2000, pp. 451–56.
Schreiber, E. C., et al. “First measurement of the near-threshold 2H(γ→,n)p analyzing power using a free-electron laser based γ-ray source.” Physical Review C Nuclear Physics, vol. 61, no. 6, Jan. 2000, pp. 616041–44.
Gonzalez Trotter, D. E., et al. “A new measurement of the 1S0 neutron-neutron scattering length using the neutron-proton scattering length as a standard.” Physical Review Letters, vol. 83, no. 19, Jan. 1999, pp. 3788–91. Scopus, doi:10.1103/PhysRevLett.83.3788. Full Text
Alexa, L. C., et al. “Measurements of the deuteron elastic structure function A(Q2) for 0.7 ≤ Q2 ≤ 6.0(GeV/c)2at jefferson laboratory.” Physical Review Letters, vol. 82, no. 7, Jan. 1999, pp. 1374–78. Scopus, doi:10.1103/PhysRevLett.82.1374. Full Text