interest: Intermediate Energy
Jefferson Lab Research
- My main research interest is experimental
medium energy nuclear physics. Studying the structure of hadrons and understanding
the transition between non-perturbative and perturbative QCD is a very
important subject in nuclear and particle physics. My research at Thomas
Jefferson National Accelerator Facility (JLab) in the previous years has been part
of this effort.
Current Physics Topics:
- One subject in which I am involved is quark-hadron duality. My involvment in this
area started with my Ph.D. topic, Inclusive
Resonance Electroproduction Data from Hydrogen and Deuterium and Studies
of Bloom - Gilman Duality, rewarded with the 1999 SURA PhD.
Thesis Award, but now, after co-authoring several papers on this subject,
I can say that this is one of my main research interests. Lately there has
been a lot of renewed interest in studying both the theoretical and
experimental aspects of quark-hadron duality in high energy physics. Being
able to describe hadronic processes in terms of quarks and gluons or in
terms of hadrons should, in principle, be possible. However, there are
still basic questions that are not answered. Several experiments at
Jefferson Lab will try to provide answers to some of these problems. Here is a list of some of the recent
experimental papers on duality. Experiment E00-002,
F2 at Low Q2,
approved by the JLab PAC in 2000 with an A- rating, on which I am
spokesperson, is one of these experiments. And here
you can view an update for this (and three other) duality experiments that
ran in Hall C in 2003.
- In addition I am the
co-spokesperson on experiment F2
at Large x (E12-10-002) which will measure H(e, e′) and D(e, e′) inclusive
cross sections in the resonance region and beyond for a precise extraction
of the F2 structure function at large Bjorken x, up to 0.99,
and intermediate four-momentum transferred squared Q2, up to
about 17 GeV2. The proposed mea-surements would be used for
detailed studies of the perturbative and nonperturbative mechanisms
underpinning the valence quark dynamics at large x. With the advance of
these studies the data could then be utilized to constrain PDFs at large
x. This experiment was chosen as one of the commissioning experiments for
Hall C and it will run in March 2017.
of Quark-Hadron Duality on the neutron.
Using the recently published data from the BONuS (Barely Off-shell
Nucleon Structure) experiment at Jefferson Lab, which utilized a spectator
tagging technique to extract the inclusive electron-free neutron
scattering cross section, we obtain the first direct observation of
quark-hadron duality in the neutron F2 structure function. The
data are used to reconstruct the lowest few (N=2, 4, and 6) moments of F2
in the three prominent nucleon resonance regions, as well as the moments
integrated over the entire resonance region. Comparison with moments
computed from global parametrizations of parton distribution functions
suggest that quark-hadron duality holds locally for the neutron in the
second and third resonance regions down to Q2≈1GeV2,
with violations possibly up to 20% observed in the first resonance region.
This paper was published in Phys.Rev. C91 (2015) 055206.
- Our group is currently
involved in the BONuS12 experiment which will run in Hall B in 2018
- I am also a collaborator on several
other JLab experiments that study duality and related phenomena
(click here to find out more
about some of these experiments). Finally, I should mention that duality
was identified as one of the important scientific goals driving the
proposed 12 GeV upgrade of Jefferson Lab.
- Our group is also involved in the 12 GeV upgrade
program at Jefferson Lab (the hodoscope detector for the new Super HMS in
Hall C). For more details see the Hall C website.
Other Physics Topics:
- Another interesting field in which I have been involved
is electromagnetic production of strangeness. This field has become
a major part of the experimental program at several nuclear and high
energy physics facilities. The production of strange quarks from the
nucleons and nuclei can give additional information for constraining
theoretical models. In collaboration with a group of physicists from
INFN Laboratory (Italy) the analysis of Sigma- photoproduction on the
neutron using data obtained at Jefferson Lab in Hall B (g10) has been
published in 2010. Currently our group is pursuing a similar analysis for Sigma-
electroproduction on the neutron using available Hall B data. Some
preliminary results were presented at PANIC2011.
NSF Support for JMU – PNP
- My research has been continuously funded by the National
Science Foundation (NSF). You can view a copy
of the current grant proposal (2013 – 2017).
in the JMU – PNP group
- We have many undergraduate students working in the JMU-PNP
(Particle and Nuclear Physics) Group. In the past few years between more
than 50 students participated in research projects in our labs. Below you
can see some pictures that my students took during summer research
- Currently JMU-PNP is no
longer an active member on MINERvA.
- For several years our group was part of the
collaboration at Fermilab. The physics program of this collaboration
includes high rate studies of exclusive final states in neutrino
scattering, elucidation of the connection between perturbative QCD and QCD
in non-perturbative regime, and studies of the axial current in the
elastic, deep inelastic and off-forward regimes. From the vast physics
program of MINERvA our group is primarily interested in the study of the transition
between the perturbative and non-perturbative regimes.
Neutrino-induced reactions can provide important consistency checks on the
validity of duality. While deep inelastic neutrino structure functions are
determined by the same set of universal parton distribution functions as
in charged lepton scattering, the structure of resonance transitions
excited by neutrino beams is in some cases strikingly different to that
excited by virtual photons. Although on general grounds one may expect
that a duality should also exist for weak structure functions, the details
of how this manifests itself in neutrino scattering may be quite different
from that observed in electron scattering.
- JMU’s main role in the construction of the
MINERvA detector was to align and test the photomultiplier tubes (PMT)
that were used for the neutrino detector. For this project our group built
an alignment stand for the M64 Hamamatsu PMTs and aligned all the
PMTs (~600) for the project. The project provided a wealth of
opportunities for undergraduate students, from designing parts using
AutoCAD and machining them in the shop, to assembling the stand and
developing the data acquisition system. As an example, Andrew Borgquist,
one of the students who worked with me during the summer of 2005 spent
some time in designing the alignment stand. Below is a picture of the
(almost) complete alignment setup.