Anton P. Tonchev, Adjunct Associate Professor  

Anton P. Tonchev

Office Location: 107 Physics, Durham, NC 27708
Office Phone: (919) 660-2501
Email Address:
Web Page:

Experimental nuclear physics

Ph.D., Joint Institute for Nuclear Research (Russia), 1995
M.S., Plovdiv University (Bulgaria), 1988
B.S., Plovdiv University (Bulgaria), 1988

Research Description: Study of the Pygmy Dipole Resonance

A common future in medium- and heavy-mass nuclei is the prevalence of neutrons over protons resulting in formation of a neutron skin. Concomitant with the development of a neutron skin is the appearance of low energy dipole strength, the so-called pygmy dipole resonance (PDR). Existing of neutron skin adds another new aspect to the dynamics of strongly asymmetric nuclear matter. It has been suggested that the PDR perceived as an excitation of the neutron-rich skin against the symmetric core may be used as a constraint on the neutron skin of heavy nuclei. Besides the genuine importance for nuclear structure physics, skin nuclei are of particular relevance for the nuclear astrophysics. For example, the existence of low-energy excitation modes related to the neutron skins could influence the rapid (r) neutron capture process in low-energy (n, γ) reactions and, therefore, will affect directly the synthesis of heavy nuclei in stellar environments.

Areas of Interest:

  • Nuclear Structure
    (collective modes of excitation, giant resonances, high-spin isomeric states)
  • Nuclear Dynamics
    (nuclear fission, gamma and particle emission, transition from chaos to order)
  • Nuclear Astrophysics
    (r-process and syntheses of rare isotopes)
  • Nuclear Applications
    (gamma and neutron activation analysis, radio isotope production, nuclear energy, nuclear transmutation, nuclear forensic)

Recent Publications   (More Publications)

  1. Tonchev, AP; Tsoneva, N; Bhatia, C; Arnold, CW; Goriely, S; Hammond, SL; Kelley, JH; Kwan, E; Lenske, H; Piekarewicz, J; Raut, R; Rusev, G; Shizuma, T; Tornow, W, Pygmy and core polarization dipole modes in 206 Pb: Connecting nuclear structure to stellar nucleosynthesis, Physics Letters B, vol. 773 (October, 2017), pp. 20-25 [doi]  [abs].
  2. Krishichayan, ; Bhike, M; Finch, SW; Howell, CR; Tonchev, AP; Tornow, W, Photofission cross-section ratio measurement of 235 U/ 238 U using monoenergetic photons in the energy range of 9.0–16.6 MeV, Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, vol. 854 (May, 2017), pp. 40-44 [doi]  [abs].
  3. Bhike, M; Tornow, W; Krishichayan, ; Tonchev, AP, Exploratory study of fission product yield determination from photofission of at 11 MeV with monoenergetic photons, Physical Review C, vol. 95 no. 2 (February, 2017) [doi] .
  4. Benouaret, N; Beller, J; Pai, H; Pietralla, N; Ponomarev, VY; Romig, C; Schnorrenberger, L; Zweidinger, M; Scheck, M; Isaak, J; Savran, D; Sonnabend, K; Raut, R; Rusev, G; Tonchev, AP; Tornow, W; Weller, HR; Kelley, JH, Dipole response of the odd-proton nucleus 205 Tl up to the neutron-separation energy, Journal of Physics G: Nuclear and Particle Physics, vol. 43 no. 11 (November, 2016), pp. 115101-115101 [doi] .
  5. Hayes, AC; Cerjan, CJ; Jungman, G; Fowler, MM; Gooden, ME; Grim, GP; Henry, E; Rundberg, RS; Sepke, SM; Schneider, DHG; Singleton, RL; Tonchev, AP; Wilhelmy, JB; Yeamans, CB, Reaction-in-Flight neutrons as a test of stopping power in degenerate plasmas, Journal of Physics, vol. 717 (May, 2016), pp. 012022-012022 [doi] .

Current Ph.D. Students   (Former Students)

    Postdocs Mentored

    • Charles Arnold (2011 - present)  
    • Rajarshi Raut (2009 - present)  
    • Elaine Kwan (2007 - 2010)  
    • Gencho Rusev (2007 - present)  
    Selected Invited Lectures

    1. Resent Results of Precision Cross Section Measurements Using Monoenergetic Neutron and Photon Beams at TUNL, November 02, 2010, CSEWG meeting, Santa Fe, New Mexico    
    2. Study of the Nuclear Electric and Magnetic Dipole Response using Monoenergetic and Polarized Photon, October 22, 2010, . 77th Annual Meeting of the Southeastern Section of the APS, Louisiana State University    
    3. Fine and Gross Structure of the Pygmy Dipole Resonance, July 04, 2010, The 24th International Nuclear Physics Conference (INPC), Vancouver, Canada    
    4. Use of Monoenergetic and Polarized Photon Beams for Basic and Applied Nuclear Physics, February 02, 2010, James Madison University    
    5. Precision Photo-Induced Cross-Section Measurements using the Monoenergetic and Polarized Photon Beams at HIGS, January 20, 2010, SSAA Symposium, Washington DC    
    6. Fine Structure of the Nuclear Dipole Response, September 29, 2009., Seminar at Ohio University, Athens, OH    
    7. Fine and Gross Structure of the Pygmy Dipole Resonance, November 11, 2009., Seminar at Michigan State University, East Lansing, MI    
    8. Study of the Pygmy Dipole Resonance, April 24, 2009., Seminar University of Kentucky, Lexington, KY    
    9. Study of the Nuclear Dipole Resonanse using the Monoenergetic and Polarized Gamma Beams at HIGS, March 30, 2009., Seminar at University of Notre Dame, South Bent, ID    
    10. Study of the Pygmy Dipole Resonance using the Monoenergetic and Polarized Gamma Beams at HIGS., June 2 - 5, 2009., Invited talk. The 3rd International Conference on "Collective Motion in Nuclei under Extreme Conditions” (COMEX 3), Mackinac Island in Michigan, United States    
    11. Study of the Nuclear Dipole Response, May 11 - 15, 2009., Invited talk. 2nd Workshop on Level Density and Gamma Strength, Oslo, Norway    
    12. Precission photo-induced cross-section measurements using the monoenergetic and polarized photon beams at HIGS., October 13 - 17, 2009, DNP meeting, Hawaii    
    13. Study of the Pygmy Dipole Resonance., August 24, 2009, Duke University, NC    
    14. Dipole Response of Bound States in N = 82 Nuclei Below Particle Threshold, April 2008, APS Meeting, St. Louis, MI    
    15. Experimental opportunity at TUNL and HIGS facility., February 13 - 14, 2009, LANL-LLNL fission workshop