This summer I divided my time among three different projects. I finished up one experiment did a little bit of work on another and I began work on a third.

For the first part of the summer I finished up an experiment involving ⁶He. ⁶He is not and ordinary nucleus. It has what is called a neutron skin. Two of its neutrons extend beyond its ⁴He core. The experiment aims at a better understanding of this skin by examining how it affects fusion.

In the experiment, conducted at the Notre Dame Nuclear Structures Lab, a stream of ⁶He particles was accelerated and shot at a ²⁰⁹Bi target at energies near the coulomb barrier (20.51 MeV and 21.97 MeV). The coulomb barrier is the minimum energy you must give the particles in order for them to overcome the coulomb repulsion force and touch. Because the particles barely come in contact the effects of the neutron skin will be significant. This reaction forms ²¹⁵At, which has a lot of excess energy. To dissipate some of that energy it evaporates off two neutrons, which leaves ²¹³At. ²¹³At alpha decays with a half-life of 125-ns. By measuring the number of alpha particles from ²¹³At the number of ⁶He that fused with ²⁰⁹Bi can be determined.

From previous work and my own, the fusion cross section is calculated for both energies. The cross section is a measure of how much fusion is occurring. It was expected that there would be an enhancement of fusion due to the neutron skin. This fusion enhancement that was previously seen in the 3-neutron evaporation channel is not seen in the 2n. With the contradiction between these results, we can only conclude that we need to know more about ⁶He before we can understand how it behaves in fusion.

The second project I worked on this summer was an experiment with ¹¹C. The experiment was conducted at the Lawrence Berkeley National Laboratory in Berkeley California. This experiment is intended to measure the pre-fission fusion cross sections for ¹¹C. The ¹¹C is collided with ¹⁹⁷Au, ¹⁹⁶Pt, ¹⁹⁶Pt, and ¹⁹⁸Pt targets to create an excited compound nuclei which fissions. Most of my work involved reanalyzing the data with a new program called IDL development environment. IDL stands for interactive data language, which is the programming language used in the program. The program is array orientated and it provides many options for visual display.

My third and current project is an experiment that was performed at the National Superconducting Cyclotron Laboratory at Michigan State University. The experiment is studying the elastic scattering of ¹⁷O and ³⁶Ar. At the present time little work has been done as far as data analysis so there is not much to say about it.

This summer I learned quite a bit about what it takes to conduct research and a lot about physics. This was accomplished while having a great time too.

Click to see a slide show of Lee Kiessel's work.