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.
Punjabi, V., et al. “Erratum: Proton elastic form factor ratios to Q2=3.5GeV2 by polarization transfer (Physical Review C (2005) 71 (055202)).” Physical Review C Nuclear Physics, vol. 71, no. 6, June 2005. Scopus, doi:10.1103/PhysRevC.71.069902. Full Text
Tornow, W., et al. “Photon analyzing power for the three-body breakup of 3He at Eγ = 15.0 MeV.” Aip Conference Proceedings, vol. 768, May 2005, pp. 138–40. Scopus, doi:10.1063/1.1932890. Full Text
Punjabi, V., et al. “Proton elastic form factor ratios to Q2=3.5GeV2 by polarization transfer.” Physical Review C Nuclear Physics, vol. 71, no. 5, May 2005. Scopus, doi:10.1103/PhysRevC.71.055202. Full Text
Mitchell, G. E., et al. “Direct nn-Scattering Measurement With the Pulsed Reactor YAGUAR.” Journal of Research of the National Institute of Standards and Technology, vol. 110, no. 3, May 2005, pp. 225–30. Epmc, doi:10.6028/jres.110.029. Full Text
Setze, H. R., et al. “Cross-section measurements of neutron-deuteron breakup at 13.0 MeV.” Physical Review C Nuclear Physics, vol. 71, no. 3, Jan. 2005. Scopus, doi:10.1103/PhysRevC.71.034006. Full Text
Mitchell, G. E., et al. “A direct measurement of the neutron-neutron scattering length.” Brazilian Journal of Physics, vol. 35, no. 3 B, Jan. 2005, pp. 850–53. Scopus, doi:10.1590/S0103-97332005000500036. Full Text
Roper, C. D., et al. “Measurements of Ay(θ) for C12(n,n)C12 from En=2.2 to 8.5 MeV.” Physical Review C Nuclear Physics, vol. 72, no. 2, Jan. 2005. Scopus, doi:10.1103/PhysRevC.72.024605. Full Text
Roper, C. D., et al. “Measurements of Aγ(θ) for 12C(n,n)12C from En = 2.2 to 8.5 MeV.” Phys. Rev, vol. C, no. 72, 2005.
Chen, Z., et al. “A dispersive optical model for n +120Sn from -15 to +80 MeV and properties of neutron single-particle and single-hole states.” Journal of Physics G: Nuclear and Particle Physics, vol. 30, no. 12, Dec. 2004, pp. 1847–59. Scopus, doi:10.1088/0954-3899/30/12/007. Full Text
Laveissière, G., et al. “Measurement of the generalized polarizabilities of the proton in virtual Compton scattering at Q2=0.92 and 1.76 GeV2.” Physical Review Letters, vol. 93, no. 12, Sept. 2004, p. 122001. Epmc, doi:10.1103/physrevlett.93.122001. Full Text