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.
Walter, R. L., et al. “The dispersive optical model for n + 208Pb and n + 209Bi.” Nuclear Inst. and Methods in Physics Research, B, vol. 79, no. 1–4, 1993, pp. 282–85.
Weisel, G. J., et al. “Neutron-proton analyzing power data between 7.6 and 18.5 MeV.” Physical Review. C, Nuclear Physics, vol. 46, no. 5, Nov. 1992, pp. 1599–606. Epmc, doi:10.1103/physrevc.46.1599. Full Text
Knibloe, J. R., et al. “Elevated-temperature behavior of fe3al with chromium additions.” Materials Science and Engineering a Structural Materials Properties Microstructure and Processing, vol. 153, no. 1–2, May 1992, pp. 382–86.
Park, B. K., et al. “Gamow-Teller and dipole strength distribution in 40Ca(n,p)40K reaction.” Physical Review. C, Nuclear Physics, vol. 45, no. 4, Apr. 1992, pp. 1791–802. Epmc, doi:10.1103/physrevc.45.1791. Full Text
Sorenson, D. S., et al. “Energy dependence of the Gamow-Teller strength in p-shell nuclei observed in the (n,p) reaction.” Physical Review. C, Nuclear Physics, vol. 45, no. 2, Feb. 1992, pp. R500–03. Epmc, doi:10.1103/physrevc.45.r500. Full Text
Tornow, W., et al. “Coulomb effects in three-nucleon scattering versus charge-symmetry breaking in the 3P nucleon-nucleon interactions.” Physical Review. C, Nuclear Physics, vol. 45, no. 1, Jan. 1992, pp. 459–62. Epmc, doi:10.1103/physrevc.45.459. Full Text
Ling, A., et al. “Ground-state Gamow-Teller strength in 64Ni(n,p)64Co cross sections at 90-240 MeV.” Physical Review. C, Nuclear Physics, vol. 44, no. 6, Dec. 1991, pp. 2794–800. Epmc, doi:10.1103/physrevc.44.2794. Full Text
Roberts, M. L., et al. “Measurement of Ay( theta ) for n+208Pb from 6 to 10 MeV and the neutron-nucleus interaction over the energy range from bound states at -17 MeV up to scattering at 40 MeV.” Physical Review. C, Nuclear Physics, vol. 44, no. 5, Nov. 1991, pp. 2006–24. Epmc, doi:10.1103/physrevc.44.2006. Full Text
Sanders, P. G., et al. “A processing method to reduce the environmental-effect in fe3al-based alloys.” Scripta Metallurgica Et Materialia, vol. 25, no. 10, Oct. 1991, pp. 2365–69.
Howell, C. R., et al. “Neutron-deuteron elastic scattering and breakup reactions below 20 MeV.” Nuclear Inst. and Methods in Physics Research, B, vol. 56–57, no. PART 1, May 1991, pp. 459–63. Scopus, doi:10.1016/0168-583X(91)96070-2. Full Text