Almost all of the visible mass that we see in the universe is contained in the atomic nucleus. It is of vital importance to gain experimental data about how nuclei are constructed to explain the early history of the universe, the abundances of the chemical elements in our solar system and even the distribution of these elements in our galaxy. An excellent nucleus to study for this purpose is the common isotope of helium, He-4. This nucleus will be a subject of study at Jefferson Lab by measuring the probability of knocking out protons with different energies using the high-energy electron beam. Another method of gaining insight into how nuclei are constructed is by placing short lived particles called hyperons in nuclei and observing the energy levels of these hypernuclei.
These experiments will provide vital training for graduate students and undergraduate students in nuclear and particle physics. The activities of these students will include helping set up the experiments, making the experimental measurements, analyzing the data and learning sophisticated simulation techniques. There is a desperate need for well trained physicists in the near future. The training the students receive has been shown to be transferable to other fields besides physics that benefit from the keen analytical skills they learn.
P { margin-bottom: 0.08in; }Scientific OutcomesOne of the missing ingredients in our understanding of nuclear structure is the distribution of neutrons in the nucleus. This state of affairs is rather distressing since protons and neutrons are the two principal components of the nucleus at low energies. The proton distribution has been accurately mapped out over many years thanks to the electromagnetic interaction which couples the beam electrons to the charged protons. With the advent of high quality electron beams at Jefferson Lab it is now possible to exploit the preferential coupling of the Z0 boson to the neutrons in the nucleus. By measuring the interference of the virtual photon and virtual Z0 exchanged by the incoming electrons we can make a clean measurement of the nuclear neutron distribution. Nuclear structure theories predict that there should be a neutron skin for nuclei with excess neutrons(N>Z). Competing theories yield different neutron root mean square radii. The best nucleus to test the theories is 208Pb where the shell model is the most applicable. Along with our Jefferson Lab collaborators we assisted in the first measurement of the neutron distribution in an atomic nucleus using the Z0 boson as a probe. The frontiers of Physics must be probed to find where our current understanding of nature fails. The scattering of electrons from electrons, as planned by the precision Møller experiment, will extend our knowledge of fundamental physics to an energy comparable to 47 TeV and test for electron substructure to a level of about 10-21 m, approximately ten times smaller than the current limit for electron substructure. This energy and distance scale is inaccessible at the Large Hadron Collider. The measurement must differentiate between two spin flip states of the incoming electron. The difference is extremely small and can be masked by contaminating background events. One background event comes from the creation of hyperons which decay in a manner dependent on the spin state of the electron. For this experiment we created the necessary software to be used in a computer simulation to estimate the size of this contamination. We completed a measurement of the nuclear reaction 4He + e → e + p +3H at high momentum transfer. 4He is an important nucleus and fundamental to our understanding of nuclear structure. 25% of the visible mass of the universe is contained in helium. We are able to compare our experimental cross sections for this reaction with theoretical models of nuclear structure. An example of the experimental results and a theoretical relativistic dynamics calculations is shown in the figure.Broader Impacts Many students from California State University, Los Angeles both at the graduate and undergraduate levels were significant contributors to these results. The graduate student whose MS thesis is based on the 4He experiment(E08009) came to the Physics and Astronomy Department with an undergraduate degree in sociology and transitioned to an MS degree in physics. She is now seeking a teaching credential. Her broaden experience will be an important asset to her students. Another graduate student was interested in medical applications of nuclear physics. He developed a Monte Carlo simulation to generate low energy neutrons from proton accelerators found at hospitals. The aim is to have a ready supply of neutrons for neutron capture therapy for cancer treatments. The present practice of Boron Neutron Capture therapy requires moving the patient to nuclear reactors. Some results from his analysis are shown in the figures for the 50 MeV and 200 MeV simulations he made. Our research group included two students who were dual majors in physics and mechanical engineering. Both these students gained valuable transferable training at Jefferson Lab which they can exploit when they enter the work force or continue into graduate school. One of our students graduated and went on to the PhD physics at the University of California, Irvine. One of our students graduated and went on to the PhD physics at the University of California, Irvine. Our students are trained to analyze large bodies of data using complex simulation programs. This is a transferable skill that is used in many fields besides scientific data analysis, for example, in economics, traffic control, the financial industries, etc.. They made significant contributions to state of the art scientific equipment for the Jefferson Lab experiments. They take this technical hardware and sofware training into the work force. Last Modified: 08/25/2014 Submitted by: Konrad A Aniol Broader Impact Research training CSULA serves many students who are the first in their families to attend college. My department is committed to providing physics and astronomy research experience for our undergraduate and graduate students. For the years 2010-2012 the American Physical Society has recognized my campus as a "top producer" in the categories of "Highest Fraction of Physics Degrees Granted to Women" and "Highest Number of Physics Degrees Granted to Underrepresented Minorities" for Master's degree institutions[38]. My collaboration, particularly with Jefferson Lab experiments, has provided undergraduate and graduate students with front line research experiences. As detailed in the previous grant period they have expanded their activities after graduation to include teaching, medical school, engineering, LHC collaborations and PhD programs. One of my former students, Omar Moreno, is now a collaborator on the Heavy Photon Search in Hall B[39]. He obtained his MS thesis on GEp(3). Educational Outreach I have taught "Ancient and Modern Views of the Universe", a history of astronomy General Education course, for the last 16 years to upper division students from all majors. The course starts with the geocentric models of Ptolemy and goes to the current level of understanding of the cosmos. One of the phenomena that must be discussed is dark matter. An interesting comparison can be made between the ancient view of celestial matter as a quintessence and this mysterious stuff that governs the motion and formation of galaxies and stars, that is, dark matter. The ancients thought that there was a different physics for celestial matter, because it was made of quintessence, compared to terrestrial matter found below the orbit of the moon because it was a composite of 4 elements. They learn that the great breakthrough came in the 17th century when the mechanics of the heavens and the earth were united by Newtonian mechanics and universal gravity. Then in the 19th century the development of spectroscopy united the chemistry of the heavens with that of the earth. Hence, we have come to a concept of universal natural law. But what should we say about dark matter? What is the meaning of a visible sector and a hidden sector of the cosmos? Here the students learn that physicists still believe in universal natural law. This is the reason we believe that our discoveries of the symmetries imposed on the Lagrangians in the visible sector is a universal phenomenon. What we see in the visible sector is mirrored in the dark sector because we believe there should be at least the U(1) symmetry common to both sectors. This comes as a revelation to the general public, which is what my GE students represent. I intend to rejuvenate the Science Series Lectures that I coordinated for many years. The last series from Fall of 2010 had a presentation by me about the parity violation experiments used to search for strange quarks in the proton. The series are addressed to the general public and notices are sent out to community colleges, high schools and departments on my own campus. They serve as an outreach to attract students to CSULA into the sciences. The lectures are especially meaningful because the speakers all come from my campus and they are encouraged to highlight research done in collaboration with their students. APEX, the Heavy Photon Search and other dark matter experiments will be great attractions. The time is opportune now since our new campus President is very keen on community engagement, of which these lectures are a good example.
