Related Experiment Videos
Signals for a transition from surface to bulk emission in thermal multifragmentation.
L Beaulieu1, T Lefort, K Kwiatkowski
1Department of Chemistry and IUCF, Indiana University, Bloomington, Indiana 47405, USA.
Physical Review Letters
|September 16, 2000
Summary
Researchers studied nuclear reactions to understand fragment emission times. They found emission times decrease significantly with increasing excitation energy, indicating a shift in emission processes.
Area of Science:
- Nuclear physics
- High-energy physics
Background:
- Studying fragment emission in nuclear reactions provides insights into nuclear matter behavior under extreme conditions.
- Previous studies have explored various excitation energies and reaction types.
Purpose of the Study:
- To investigate the relationship between excitation energy and fragment emission time in nuclear reactions.
- To understand the underlying mechanisms governing fragment emission, such as multifragmentation and radial expansion.
Main Methods:
- Analyzed excitation-energy-gated two-fragment correlation functions.
- Studied reactions involving pi(-) and p+197Au at 8-10 GeV/c.
- Compared experimental data with an N-body Coulomb-trajectory code.
Main Results:
- Observed an order of magnitude decrease in fragment emission time between E(*)/A = (2-5)A MeV.
- Found fragment emission time becomes nearly constant at higher excitation energies (E(*)/A > 5A MeV).
- Correlated the decrease in emission time with the onset of multifragmentation and thermally induced radial expansion.
Conclusions:
- The observed decrease in emission time suggests a transition from surface-dominated to bulk emission.
- Results are consistent with spinodal decomposition as the mechanism driving this transition.
- Fragment emission dynamics are strongly influenced by excitation energy and multifragmentation phenomena.