Department Directory

Nuclear Physics

Ronald Gilman - home page

Directory information

Position: Professor
Research group: Experimental nuclear physics
Email address:
Telephone: (848) 445-8775 (but email is much better)
Office: Serin W212
Mailing address: Ronald Gilman
  Department of Physics and Astronomy
Rutgers, The State University of New Jersey
136 Frelinghuysen Road
Piscataway, NJ 08854-8019 USA

Teaching Activities

Research Activities

The proton radius puzzle, originally published by Randolf Pohl et al. in Nature in July 2010 is a recent high profile issue - the proton size appears to be different when measured with electons vs. when measured with muonic hydrogen, a result for which we have no explanations. Experts in the field think the likely explanation is either new physics or issues with electron experiments. Novel aspects of proton structure / QCD are not entirely ruled out, although almost every suggestion made to date in this area has been. The puzzle has been confirmed with a second paper by Aldo Antognini et al. with new muonic hydrogen results. The muonic hydrogen measurements were done at the Paul Scherrer Institut, a laboratory in Switzerland. A press release from PSI is here. A good podcast with Aldo Antognini describing the situation is here. You can also see informal descriptions of the Puzzle and reactions to it from may sources, including Science Daily, New Scientist, Science News, Red Orbit, arstechnica,, Huffington Post, Nature News, and Scientific American. A news conference on the Puzzle with Randolf Pohl, Jan Bernauer, and John Arrington was reported on at Huffington Post, and Yahoo news.

I co-organized a Proton Radius Puzzle Workshop at the European Center for Theory in Trento, Italy with Randolf Pohl (Munich) and Gerald Miller (Washington), and we, with Krzysztof Pachucki (Warsaw) wrote a review paper on the current status of the puzzle. I am also leading an experimental effort to study the puzzle with muon-proton elastic scattering - some materials can be found here.

I usually work with Prof. Ron Ransome and colleagues from other universities and laboratories from around the world in an area called intermediate energy nuclear physics. We mainly investigate strong QCD (mostly the structure of the proton and neutron), nuclear structure, and physics beyond the standard model. Our focus has been experiments at the Thomas Jefferson National Accelerator Facility (JLAB) 6 GeV electron accelerator, CEBAF, in Virginia and at Fermilab, in Batavia Illinois. Our JLab research is centered on studies of spin physics, studying nucleons and subnucleonic effects in light nuclei using polarized electron beams, targets, and recoil polarimeters. Our research at Fermilab uses neutrino beams and proton beams to study quark distributions and QCD through the Drell-Yan process.

More information, with links and some future plans, can be found in the nuclear group experimental online projects page.


A nearly complete list of my publications can be found with a SLAC SPIRES search, in default ordering, or ordered by number of citations. This list is regularly updated. Following are some selected recent publications, much less regularly updated.

New measurement of the proton's size and structure using polarized photons X. Zhan et al. submitted to Science
Polarization Observables in Deuteron Photodisintegration below 360 MeV J. Glister et al. preprint, submitted to Phys. Lett. B
Search for effects beyond the Born approximation in polarization transfer observables in ep elastic scattering M. Meziane et al. preprint, submitted to Phys. Rev. Lett.
Measurements of the Electric Form Factor of the Neutron up to Q2=3.4 GeV2 using the Reaction 3He(e,e'n)pp S. Riordan et al. preprint (accepted by Phys. Rev. Lett.
Polarization Transfer in the 4He(e,e'p)3H Reaction at Q2 = 0.8 and 1.3 (GeV/c)2 M. Paolone et al. preprint, Phys Rev Lett 105, 072001, 2010
Hard Photodisintegration of a Proton Pair I. Pomerantz et al. Phys Lett B (2010) or preprint
Probing Cold Dense Nuclear Matter R. Subedi et al. Science 320, 1476 (2008)
The Proton Elastic Form Factor Ratio μp GEp/GMp at Low Momentum Transfer G. Ron et al. Phys Rev Lett 99, 202002 (2007)
Investigation of proton-proton short-range correlations via the 12C(e, e' pp) reaction R. Shneor et al. Phys Rev Lett 99, 072501 (2007)
Recoil-Proton Polarization in High-Energy Deuteron Photodisintegration with Circularly Polarized Photons X. Jiang et al. Phys Rev Lett 98, 182302 (2007)
Precision Measurements of the Nucleon Strange Form Factors at Q2 ~ 0.1 GeV2 A. Acha et al. Phys Rev Lett 98, 032301 (2007)
Scaling tests of the cross-section for deeply virtual compton scattering C. Munoz Camacho et al. Phys Rev Lett 97, 262002 (2007)
Parity-violating electron scattering from He-4 and the strange electric form-factor of the nucleon K. A. Aniol et al. Phys Rev Lett 96, 022003 (2006)
Constraints on the nucleon strange form-factors at Q2 ~ 0.1 GeV2 K. A. Aniol et al. nucl-ex 0506011
Phys. Lett B635, 275 (2006)
Recoil polarization for delta excitation in pion electroproduction J. J. Kelly et al. Phys Rev Lett 95, 102001 (2005)
Proton elastic form-factor ratios to Q2 = 3.5 GeV2 by polarization transfer V. Punjabi et al. Phys Rev C 71, 055202 (2005);
Phys Rev C 71, 069902 (2005)
Polarization transfer in proton Compton scattering at high momentum transfer D. J. Hamilton et al. Phys Rev Lett 94, 242001 (2005)
Precision Rosenbluth measurement of the proton elastic form-factors I.A. Qattan et al. Phys Rev Lett 94, 142301 (2005)
Measurement of R = σL/ σT and the separated longitudinal and transverse structure functions in the nucleon resonance region
Y. Liang et al. nucl-ex 0410027
Higher Twists and Color Polarizabilities in the Neutron Z.-E. Meziani et al. Phys Lett B 613, 148-153 (2005)
Measurement of the 3He(e,e'p)pn reaction at high missing energies and momenta F. Benmokhtar et al. Phys Rev Lett 94, 082305 (2004)
Experimental Determination of the evolution of the Bjorken integral at low Q2 A. Deur et al. Phys Rev Lett 93, 212001 (2004)
Measurement of the Generalized Forward Spin Polarizibilities of the Neutron M. Amarian et al. Phys Rev Lett 93, 152301 (2004)
Q2 Evolution of the Neutron Spin Structure Moments using a 3He Target M. Amarian et al. Phys Rev Lett 92, 022301 (2004)
Precision Measurement of the Neutron Spin Asymmetry An1 and Spin-Flavor Decomposition in the Valence Quark Region X. Zheng et al. Phys Rev Lett 92, 012004 (2004)
Hard Photodisintegration of a Proton Pair in 3He S. Brodsky et al. nucl-th 0305068
Phys Lett B 578, 69 (2003)
Polarization Transfer in the 4He(e,e'p)3H Reaction up to Q2 = 2.6 (GeV/c)2 S. Strauch et al. Phys Rev Lett 91, 052301 (2003)
A Search for Neutral Baryon Resonances Below Pion Threshold X. Jiang et al. Phys Rev C 67, 028201 (2003)
The Q2 evolution of the generalized Gerasimov -- Drell -- Hearn integral for the neutron using a 3He target M. Amarian et al. Phys Rev Lett 89, 242301 (2002)
Polarization measurements in neutral pion photoproduction K. Wijesooriya et al. Phys Rev C 66, 034614 (2002)
Electromagnetic Structure of the Deuteron R. Gilman and Franz Gross J. Phys. G 28, R37-R116 (2002)
Meausrement of Gep/GMp in ep --> ep to Q2 = 5.6 GeV2 O. Gayou et al. Phys Rev Lett 88, 092301 (2002)
Measurements of the elastic electromagnetic form factor ratio mu_p G_Ep / G_Mp via polarization transfer O. Gayou et al. Phys Rev C 56, 038202 (2001)
New Measurement of Parity Violation in
Elastic Electron-Proton Scattering and
Implications for Strange Form Factors
K.A. Aniol et al. nucl-ex 0006002
Phys Lett B 509 211-216 (2001)
Polarization measurements in high-energy deuteron photodisintegration K. Wijesooriya et al. Phys Rev Lett 86, 2975 (2001)
The charged pion form factor J. Volmer et al. Phys Rev Lett 86, 1713 (F2001)
The Transverse Asymmetry AT' from Quasi-elastic 3He(e,e') Process and the Neutron Magnetic Form Factor W. Xu et al. Phys Rev Lett 85, 2900 (2000)
Phenomenology of the deuteron electromagnetic form factors D. Abbott et al. xxx preprint 00-02-003
Euro Phys Journal A vol 7, 421 (2000).
Measurement of Tensor Polarization in Elastic Electron-Deuteron Scattering at Large Momentum Transfer D. Abbott et al. Phys Rev Lett 84, 5053 (2000)
The ratio of proton's electric to magnetic form factors measured by polarization transfer M. K. Jones et al. Phys Rev Lett 84, 1398 (2000)

Please send any comments on this page to

Revised Fenruary 4, 2014