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

 

Giant resonances in nuclei can be thought of as collective motion of the nucleons within the nucleus. Accelerator-based experiments have probed these excitations of nuclear matter for several decades. However, there have been relatively few measurements of giant resonances using inelastic scattering of heavy ion projectiles. It has been suggested that heavy ions would produce higher cross sections and the possibility of selectively exciting resonances of high angular momentum. Measurements of this sort are important to understand the nature of nuclear structures at high excitation energy and angular momentum. An experiment was conducted at the National Super Conducting Cyclotron Laboratory using projectiles of ¹⁷O and ³⁶Ar and targets of ⁹⁰Zr and ²⁰⁸Pb at intermediate bombarding energies (84-150 MeV/A). The energy and paths of the scattered particles after the collision were measured with the S800 spectrometer. Figure 1 shows the setup of the S800.

Figure 1
 

The analysis of these data has been compared against a folding model that describes a simple and effective interaction between nuclei at intermediate energies. Figure 2 shows the comparison of the ¹⁷O data with the model predictions.

Figure 2

The next step is to do the same analysis for the ³⁶Ar runs and to modify the model calculations to more closely fit the data.
_____________________________________________________________________________________________________________________________________________________________________Publications and Presentations:
“The (⁸Li, α) reaction at Low Energy: Direct ⁴H Cluster Transfer?” F.D. Becchetti, R.S. Raymond, D.A. Roberts, J. Lucido, P.A. DeYoung, B. Hilldore*, J. Bychowski*, A.J. Huisman*, P.J. VanWylen*, J.J. Kolata, G. Rogachev, and J.D. Hinnefeld. Phys. Rev. C 71, 054610 (2005).
“²⁰⁹Bi(⁶He,α) Reaction Mechanisms Studied Near the Coulomb Barrier Using n-α Coincidence Measurements.” J.P. Bychowski*, P.A. DeYoung, BB. Hilldore*, J.D. Hinnefeld, A. Vida*, F.D. Becchetti, J. Lupton, T.W. O’Donnell, J.J. Kolata, G. Rogachev, and M. Hencheck. Phys. Lett. 596B, 26 (2004).
“Study of the (⁸Li,α) Reaction at Low Energy: Direct ⁴H Transfer?” F.D. Becchetti, D.A. Roberts, J. Lucido, P.A. DeYoung, B. Hilldore*, J. Bychowski*, J.J. Kolata, and G. Rocharchev. The Sixth International Conference on Radioactive Nuclear Beams, Argonne, Il, September 2003.
“Analysis of Event-Mode Data with Interactive Data Language.” P.A. DeYoung, B.B. Hilldore*, L.M. Kiessel*, and G.F. Peaslee. Nucl. Instr. and Meth. A 505, 294 (2003).
“Coulomb Excitation of Giant Resonances with Heavy Ion Projectiles.” B.B. Hilldore*, B. Atallah*, P.A. DeYoung, L.Kiessel*, M.K. MacDermaid*, G.F. Peaslee, D. Bazin, K. Govaert, B. Sherrill, M. Thoennessen, J. Beene, B. Blank, M. Chartier, F. Liang, R. Varner. Paper 5P1.073. Division of Nuclear Physics Fall Meeting. East Lansing, MI, October 2002.
“Understanding the ²⁰⁹Bi(⁶He,⁴He) Reaction Mechanisms Near the Coulomb Barrier.” J.P. Bychowski*, P.A. DeYoung, B.B. Hilldore*, J.D. Hinnefeld, A. Vida, F.D. Becchetti, J. Lupton, T.W. O’Donnel, J.J. Kolata, G. Rogachev, and M. Hencheck. Paper 5P1.072. Division of Nuclear Physics Fall Meeting. East Lansing, MI, October 2002.
“Analysis of Event-Mode Data with Interactive Date Language.” P.A. DeYoung, B.B. Hilldore*, L.M. Kiessel*, and G.F. Peaslee. 2002 Symposium on Radiation Measurements and Applications, University of Michigan, April 2002.
“Sizes of Nuclei.” Benjamin Hilldore*, and P.A. DeYoung. PEW Midstates Consortium Undergraduate Research Symposium, University of Chicago, November 2001.