Calvin R. Howell

Calvin R. Howell

Professor of Physics

Office Location: 
221 Dfell, Durham, NC 27708
Front Office Address: 
Box 90308, Durham, NC 27708-0308
(919) 660-2632


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. 

Education & Training

  • Ph.D., Duke University 1984

Tonchev, A. P., et al. “Study of collective dipole excitations below the giant dipole resonance at HIγS.” Aip Conference Proceedings, vol. 891, Apr. 2007, pp. 339–47. Scopus, doi:10.1063/1.2713535. Full Text

Anderson, B., et al. “Extraction of the neutron magnetic form factor from quasielastic 3He→(e→,e') at Q2=0.1-0.6 (GeV/c)2.” Physical Review C  Nuclear Physics, vol. 75, no. 3, Mar. 2007. Scopus, doi:10.1103/PhysRevC.75.034003. Full Text

Floyd, C. E., et al. “Neutron stimulated emission computed tomography: Background corrections.” Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions With Materials and Atoms, vol. 254, no. 2, Jan. 2007, pp. 329–36. Scopus, doi:10.1016/j.nimb.2006.11.098. Full Text

Howell, C. R. “Extracting the neutron-neutron scattering length from neutron-deuteron breakup.” Chiral Dynamics 2006  Proceedings of the 5th International Workshop on Chiral Dynamics, Theory and Experiment, Cd 2006, Jan. 2007, pp. 344–45. Scopus, doi:10.1142/9789812790804_0058. Full Text

Floyd, Carey E., et al. “Introduction to neutron stimulated emission computed tomography.Phys Med Biol, vol. 51, no. 14, July 2006, pp. 3375–90. Pubmed, doi:10.1088/0031-9155/51/14/006. Full Text

Sharma, A., et al. “Rotating slat collimator design for high-energy near-field imaging.” Progress in Biomedical Optics and Imaging  Proceedings of Spie, vol. 6142 I, July 2006. Scopus, doi:10.1117/12.653929. Full Text

Floyd, C. E., et al. “Breast cancer diagnosis using neutron stimulated emission computed tomography: Dose and count requirements.” Progress in Biomedical Optics and Imaging  Proceedings of Spie, vol. 6142 II, June 2006. Scopus, doi:10.1117/12.656045. Full Text

Tonchev, A. P., et al. “Low-energy dipole modes of excitation below the neutron separation energy.” Aip Conference Proceedings, vol. 819, Mar. 2006, pp. 350–54. Scopus, doi:10.1063/1.2187883. Full Text

Plaster, B., et al. “Measurements of the neutron electric to magnetic form factor ratio GEn/GMn via the H2(e→,e'n→)H1 reaction to Q2=1.45 (GeV/c)2.” Physical Review C  Nuclear Physics, vol. 73, no. 2, Mar. 2006. Scopus, doi:10.1103/PhysRevC.73.025205. Full Text

MacLachlan, G., et al. “The ratio of proton electromagnetic form factors via recoil polarimetry at Q2 = 1.13 (GeV/c)2.” Nuclear Physics A, vol. 764, no. 1–4, Jan. 2006, pp. 261–73. Scopus, doi:10.1016/j.nuclphysa.2005.09.012. Full Text