Hope College Department of Physics and Engineering
Research Experiences for Undergraduates
Summer 2002
Project Summary

Project Title: The MoNA Project

Student Name: Peter VanWylen
Student’s home institution: Hope College
Research Advisor(s): Dr. P. A. DeYoung, Dr. G. F. Peaslee
Source of Support (NSF-REU, or other): NSF

This summer I have worked on several different projects.These include the MoNA Project, the 4H Transfer Project, and the BEARS / PACE project.MoNA, or Modular Neutron Array, is a project involving the construction of a new high-efficiency Neutron Detector Array. The 4H Transfer Project is an experiment done at the Notre Dame Nuclear Structure Lab looking at a possible 4H transfer from a radioactive beam of 8Li to various targets.The BEARS / PACE project involves the investigation of inconsistencies between some old and new measurements of the 197Au(11C,xn)208-xAt reaction.
 

As part of the MoNA project, I built 16 neutron detector slats which will be used in a larger array containing 144 neutron detectors at the NSCL, or National Superconducting Cyclotron Laboratory. The construction of these involved assembly of photomultiplier assemblies and the attachment of these assemblies to each of the neutron detector slats. The neutron detector slats are made of scintillating plastic, which fluoresces when hit by a neutron. The light given off by such events is detected by the photomultiplier tubes, and time difference information between left and right photomultipliers is used to determine exact position of detected events.

After construction of these slats, I spend several weeks testing each one of them. Testing showed that each of them worked properly and that after some simple gain-matching of photomultipliers, all slats gave similar testing results. In light attenuation measurements, however, data was too curved to fit the expected exponential decay model. In an attempt to better understand this, my professor and I wrote a ray-tracing program to simulate light propagation in the slat. While results from this program are still preliminary, they do reproduce some of the unexpected results.

The 4H transfer project that I am working on is still in the preliminary data processing and analysis stages. Essentially, a previous experiment has shown what some believe to be a 4H transfer from a radioactive beam of 8Li onto a target. In an attempt to confirm or invalidate this hypothesis, a new experiment was done at Notre Dame. The three targets tested were 27Al, 12C, and 208Pb. So far data processing has been done to put the data in IDL format (to work with our analysis program), and gates have been created to isolate alpha-particle events, which are of interest in this experiment. Some preliminary spectra have been generated and sent to collaborators for their analysis.

Finally, I have done some work on the BEARS / PACE project. BEARS stands for Berkeley Experiments with Accelerated Radioactive Species. My work involved resolving some inconsistencies in some old and new measurements of 197Au(11C,xn)208-xAt reaction cross-sections. In the end, I found that there was a simple scalar multiple that related the older and newer results. Finally, I re-ran some PACE statistical calculations based on these new-scaled results. This analysis is ongoing and will hopefully provide information on the possible difference between 11C and 12C reaction cross-sections.