REU Project Abstracts Summer 2009 -- Preliminary

 

Nuclear Physics – Experimental

 

Title: Optical-pumping schemes and system for production of atomic polarization

Supervisors: Prof. Paul Mantica and Dr. Kei Minamisono

Abstract:  We are implementing a collinear laser beam line at NSCL to produce polarized beams of rare isotopes via laser optical pumping.  Reliable knowledge of atomic hyperfine energy levels and pumping scheme for a cyclic laser transition is essential for the successful production of atomic polarization.  However, for most elements, the excitation schemes accessible by commercially available laser systems have not been well investigated.  The goal of the REU project is to search the literature to identify the hyperfine energy levels and possible optical-pumping schemes for light transition metals (V, Cr, Mn, Fe, Co, ...).  The participating student will also assist with installation of the laser system, which is schedule to arrive at NSCL in mid June.

 

Title: CAESAR's Reign   (available for 2 students)

Supervisors: Prof. Alexandra Gade and Dr. Dirk Weisshaar

Abstract: NSCL is completing the construction of the high-efficiency scintillator array CAESAR (CAESium iodide ARray). This detector array consists of 192 CsI(Na) scintillation crystals with photomultiplier readout. This detection system coupled to NSCL's magnetic spectrograph will be commissioned in May 2009 for in-beam gamma-ray spectroscopy of

exotic nuclei. CAESAR's response to gamma-rays emitted at rest (calibration source) and emitted from a moving source (exotic nuclei passing through at 40% of the speed of light) has to be characterized in comparison to simulations that take into account the geometry of the setup as well as  the property of the detection material (GEANT4). We invite two students to join this effort over the summer and to participate in two actual CAESAR experiments which are scheduled to run in June and July at NSCL. Some programming experience would be desired.

 

Title:  Investigating the Discovery of Isotopes (available for 2 students)

Supervisor: Prof. Michael Thoennessen

Abstract:  There are many combinations of neutrons and protons that can make up a nucleus (isotope) of a given mass.  Only 300 isotopes are stable and a few thousand more radioactive isotopes are known.  However, there are still thousands of nuclei that have not been discovered.  The limit of existence is only known for the lightest elements.  Major new accelerator facilities are being built and designed around the world that will be able to produce many new very exotic nuclei.  We recently started a project to document the discovery of all isotopes.  The REU project involves the research to identify the discoveries of isotopes for a given element and write a summary paper.  Atomic Data and Nuclear Data Tables, a major refereed scientific journal has agreed to publish these papers.  Thus the REU student will have a great opportunity to be the first author of at least one publication.

 

Title:   Modular Neutron Detector Array (available for 2 students)

Supervisor:  Prof. Michael Thoennessen

Abstract:  The Modular Neutron Detector Array (MoNA) is a large area, high efficiency neutron detector designed for neutrons stemming from breakup reactions of fast rare isotope beams.  MoNA was built by a collaboration of predominantly undergraduates schools which continue to collaborate on the experiments.  This summer will start with an experiment to measure the decay energy of the low-lying neutron-unbound state of C-21.  The week-long experiment starts June 1st, and the REU students will have the unique opportunity to participate in a cutting-edge nuclear physics experiment.  After the experiment is completed, the REU students will be involved in the data analysis and physical interpretation of the collected data.

 

Title:  Get Trapped: Ion traps for precise mass measurements

Supervisor:  Prof. Georg Bollen and Dr. Ryan Ringle

Abstract:  The Low-Energy Beam and Ion Trap facility at the NSCL performs high precision mass measurement of unstable “rate” isotopes.  Such measurements are important since they provide information on the binging energy of a nucleus, which is one of its most fundamental properties.  A LEBIT such measurements have been very successfully carried out with a Penning trap mass spectrometer.  This is an instrument in which single ions can be trapped in space and that allows mass measurements of atoms with a relative precision of better than about 1 part in 100 million.  The LEBIT facility is likely to be relocated in summer or early fall 2009 and as part of this move will be upgraded and improved.  Examples of possible REU projects within the LEBIT project are development and test of electronic components, Monte-Carlo computer simulations of the motion of ions in electrostatic beam transport system and in various types of ion traps, the further development of data evaluation for LEBIT.  The student may also be involved in interesting hands-on work related to the disassembly and reassembly of complex LEBIT facility.

 

Title:  Neutron and proton spectra as a probe for symmetry energy

Supervisor:  Prof. Bill Lynch,  http://www.nscl.msu.edu/`lynch/

Abstract:  Theoretically, it is predicted that, under right conditions, nuclear matter undergoes the liquid-to-gas phase-transition and that an excess of neutrons accumulates in the low-density (gaseous) phase.  This phenomenon can be used to study the symmetry energy which is the energy penalty paid when the number of neutrons and protons in a nucleus is not the same.  Symmetry energy is a fundamental property not only in describing normal nucleus but also in understanding properties of the neutron stars.  To study the problem, we have measured the ratios of the free neutron (n) yields to free proton (p) yields from the more proton-rich 112Sn+112Sn collisions and the more neutron-rich 123Sn+124Sn collisions.    http://www.nscl.msu.edu/ourlab/news/2009/nscl-researchers-constrain-symmerty-energy-low-density.  In this project, we would like to work with an REU student to study the yield ratios of n/p from models utilizing transport equations using the MSU high performance computing center as well as the Texas Advanced Computing Center.  It is important that the student is proficient in programming and familiar with the Linux operating systems.  The student will have opportunities to work on an experiment or help with data analysis.

 

Title:  Probing the single particle structure in nuclei

Supervisor:  Dr. Betty Tsang, http://www.nscl.msu.edu/`tsang/

Abstract:  The 1963 Nobel Prize in physics was awarded to Maria Goeppert Mayer and Hans Jensen for their explanation of the structure of nuclei.  The success of the Shell Model to explain the existence of the magic numbers of 2, 8, 20, 28, 50, 82 and 128 in neutron and protons has prompted the speculations that the closed shell can be treated as an inert core and the valence nucleons outside this core can be treated as independent particles.  Such simple model allows the understanding of many observed nuclear properties.  It also prompted many studies in the past 4 decades to describe the configuration of single particle orbits.

Recent advance in radioactive beams by using nuclei far away from stability has revived interest in measuring single particle structure in nuclei.  There is evidence that the traditional view of the simple shell models will be modified for these exotic nuclei.  Currently the only technique to study the single particle configuration of a wide range of nuclei from stable to very unstable isotopes is to use transfer reactions.  Thus it is important to establish reference points in the stable nuclei region allowing reliable extrapolations to rare isotopes.

The objective of this project is to use a consistent analysis procedure that our group has developed to analyze the past transfer reaction data published in the literature [see for example, http://www.nscl.msu.edu/`tsang/sf_slide_show_08.pdf   The extracted data will be invaluable for nuclear model development.  Experiments on transfer reactions will be scheduled to run at the National Superconducting Cyclotron Laboratory next year.  Depending on the student’s interest, the REU student is encouraged to participate in the detector development such as testing of multi-channel plate detectors in the preparation of such an experiment.

 

Accelerator Physics

 

Title: Charge breeding of rare isotopes in an electron beam ion trap (EBIT):

SUPERVISORS: Dr. Stefan Schwarz and Prof. Oliver Kester

Abstract: Within the ReA3 re-accelerator project (http://www.nscl.msu.edu/features/stoppedand-

re-accelerated-beams), the NSCL presently builds an electron beam ion trap (EBIT), which is used to convert singly charged ions of rare isotopes into highly-charged ions. Such charge state boosting is the key to very efficiently accelerate rare isotopes in a linear accelerator to energies interesting for a variety of nuclear physics experiments. An EBIT employs an intense electron beam focused by a strong magnetic field of a superconducting magnet. The electron beam enhances the charge state of externally injected ions by electron impact ionization. To confine the ions inside the electron beam, a potential well has to be provided by a drift tube structure surrounding the electron beam.  Examples of possible REU projects within the MSU-EBIT project are investigations of the characteristics of the electron gun of the EBIT, electron beam properties in comparison with numerical simulations with codes available at the lab, investigations of the required potential distribution for ion manipulation in the charge state breeder including programming with MATLAB©. The student may be involved in test of the mass separator of the charge breeder or in hands-on assembly of charge breeder components.

 

Nuclear Physics – Theoretical

 

Title: Systematic trends in nuclear reactions

Supervisor: Prof. Filomena Nunes

Abstract: Nuclear reactions continue to be a very important tool to study unstable exotic nuclei, some of which are presently produced at the NSCL and many to be produced at the new facility FRIB.  We will look specifically at two types of reactions, (d,p) and (d,n), the first which connect to energy programs and the second which has an impact in astrophysics.

 

Title:  Modeling Relativistic Heavy Ion Collisions

Supervisor:  Prof. Scott Pratt

Abstract: Experiments at RHIC (The Relativistic heavy Ion Collider) at Brookhaven Natl. Laboratory on Long Island, investigate collisions of high-energy nuclei.  In these collisions, mesoscopic regions are created with temperatures thousands of times hotter than the interior of the sun.  At these temperatures, hadrons (e.g. protons) melt into their constituent quarks and gluons and fundamental vacuum QCD condensates dissolve.  These collisions last only 10^-22 seconds, and measurements are confined to identifying and recording the asymptotic momenta of the thousands of particles that might be created in a single event.  Thus, modeling represents an inherently critical element for RHIC physics.  The REU student working on this project would apply hydrodynamic-based treatments to model the collision, and also apply femtoscopic methods to extract space-time information from two-particle correlations.  The work would involve significant programming in C++.

 

Title:  Simple Quantum systems interacting with external noise

Supervisor:  Prof. Vladimir Zelevinsky

Abstract:  Usually quantum mechanics of simple systems considers a “pure case” of an isolated atom, molecule, nucleus, etc.,  In reality in many situations the systems are subject to interactions with environment.  Such interactions are responsible for the decoherence – quenching of quantum correlations and for chaotic missing of quantum states.  If the environment can be modeled by thermostate (a heat bath), the system comes to thermal equilibrium.  In other cases the resulting state of the system can be more complicated.  The problem acquires special importance when we think of future quantum computers – the decoherence there is the main danger.  One of the tools for analyzing the interaction of a quantum system with noise is quantum entropy that can be introduced in different ways.  I suggest to study the so-called correlation entropy of simple quantum systems in order to understand the behavior od a quantum object subject to noise that is not supposed to be weak.  This might be an interesting project for a student with inclination to analytical work.

 

Nuclear Astrophysics and Astronomy

 

Title:  Magnetic fields and starquakes

Supervisor: Prof. Edward Brown and Dr. Andrew Steiner

Abstract:  Neutron stars, the densest objects which are directly observable, are thought to have “starquakes”.  These starquakes (very similar to terrestrial earthquakes) cause a catastrophic change n the neutron star crust which leads to a giant gamma-ray flare (see www.youtube.com/watch?v=xTIKUYu1RPk).  Starquakes have only been observed in highly magnetized neutron stars, yet the effects of the magnetic field has not been fully explored.  We have an opening for one student to help us explore the impact magnetic fields will have.  A bit of computer programming experience would be helpful.

 

Condensed Matter Physics – Experimental

 

Title: Coherent control and quantum optics in semiconductor nanostructures

(experience/knowledge in optics is required)

Supervisor: Prof. Chih-Wei Lai

Abstract: The summer project will involve construction of an ultrafast pulse shaper for

coherent quantum control, autocorrelator/interferometer for laser pulsecharacterization, or laser intensity stabilizer based on a acousto-opticalmodulator and a PID controller.

Our research is in the broad field of light-matter interaction, with an emphasis on many-body physics, quantum optics, nonlinearoptics, and laser spectroscopy in semiconductors.

In particular, we are interested in (i) understanding the many-body interactions and quantum collective phenomena and (ii) developing optical manipulation and coherent control of electron and nuclear spins effects in low-dimensional nanostructures such as quantum wells, wires and dots. These are mesoscopic material systems whose sizes, on the order of nanometers, are intermediate between those of atoms and bulk solids. The quantum size effects dramatically reshape the many-body interactions; therefore, these systems are ideal testbeds for understanding both (a) quantum collective phenomena (eg. quantum Hall effects and Bose-Einstein condensation) and (b) isolated quanta with long coherence time (eg. electron and nuclear spins in quantum dots).

 

Title: Ultrafast Nanocrystallography and Nanolithography (available for 2 students)

Supervisor: Prof. Chong-Yu Ruan

Abstract: Nanoscience is the buzzword for studying things that are small but unique in their property because of their small size. These objects are too small for human eyes or typical optical microscope to see, and to investigate their function one faces challenges from huge dispersion of sample sizes and the complexity of their interaction with their environments and within. We have recently successfully imaged the dynamical transformation of very small gold and silver nanoparticles (size-selected from 1 to 20 nm in diameter) using femtosecond diffraction camera. Because of our shutter speed is ultrafast, the atomic motion within the nanoparticles is thus frozen in time. By capturing these acts at the critical steps of transformations, we highlight the effects that are unique to their size and composition. For example, these noble metals become very reactive when their size is close to 1 nm, and they change into a semiconductor around 5 nm. We are now expanding these efforts to include studying their electronic and compositional transformation that cannot be seen from optical spectroscopic method (meaning by observing the electronic transition in these materials using light). Many of these “dark” transformations are key to understand the hidden mechanism for energy conversion, a potential field nanotechnology can help to solve the energy crisis. We are also exploring using nanolens made by nanoparticles to defeat diffraction limit, so we can produce nanoscale features to trap liquids and gases to study chemistry and biology. We would like to invite interested students to help us to explore these areas, where light and atom, ultrafast and ultrasmall meets. The students will help conduct experiments and simulations related to nanostructures and energy transformations, design instruments that couple to ultrashort pulses, and detect the electronic, structural and compositional changes.

 

Title: Superconductivity and Magnetism

Supervisor: Prof. Norman Birge

Abstract: Superconductivity and magnetism are the two most well-known ways in which metals change their properties as the temperature is lowered.  They are usually viewed as incompatible with each other, because superconductivity requires electrons to be paired with their spins antiparallel, whereas ferromagnetism favors parallel spin alignment.  When conventional superconductors and ferromagnets are placed in contact with each other, the resulting hybrid samples exhibit many new physical properties.  An REU student working on this project will fabricate his or her own multilayer samples, measure the electric or magnetic properties of those samples, and help us interpret the results. 

 

Condensed Matter Physics - Theoretical

 

Title: Frustrated classical Heisenberg spin model with added biquadratic interactions

Supervisor:  Prof. Tom Kaplan

Abstract:   The many-body problem of classical spins on a linear chain lattice, interacting with competing Heisenberg exchange interactions plus biquadratic exchanges interactions was studied (Kaplan, unpublished) and found to have an interesting ground state phase diagram.  It shows ferromagnetic, incommensurate spiral, and “up-up-down-down” phases.  The problem to be addressed is the extension too higher-dimensional lattices.  Closely related models have been of considerable interest, partially because they are probably relevant to experimental results on some manganites; in particular, the up-up-down-down state has been observed in e.g. HoMnO3, the origin of which as been considered mysterious.

 

Title: Statistical physics of biological networks

Supervisor: Profs. Carlo Piermarocchi and Phil Duxbury

The project involves the modeling of signaling in complex gene regulatory networks using tools from statistical physics and information theory. Comparison of theoretical models with gene expression data will be carried out. The student interested in working on this project should have some programming skills and knowledge/willing to learn Mathematica.