Engineering topics

Depastas, T.

Publications and source records attributed to Depastas, T..

3 records

DOE OSTI2024

Heavy ion induced e + e − pair production: Theoretical and preliminary experimental efforts

The production of real e + e − pairs is an important quantum electrodynamics phenomenon, that could have significant implications on low energy heavy ion dynamics. Here, we employ an established Schwingerinspired theory to study this effect in nuclear disintegrations. We extend the current framework with a Monte Carlo approach to include non-perturbative contributions. Simultaneously, we supplement our study with a preliminary experimental procedure, via the use of the Global Spectrometer for Positron and Electron Characterization developed at the Texas Petawatt Laser facility of the University of Texas at Austin. Theory and experiment agree within one order of magnitude, which signals promise for further investigations.

Depastas, T.↗

DOE OSTI2023

α -cluster microscopic study of C 12 + C 12 fusion toward the zero energy limit

The carbon burning process is a fundamental step of stellar evolution and governs the synthesis of chemical elements important for the formation of life. In this work, we utilize the microscopic hybrid α cluster (HαC) model and an analytical approach, both in the framework of the Imaginary Time Method (ITM), to study the carbon fusion reaction towards zero energy. We obtain the values of the cross sections, astrophysical factors and correlate our results to collective motion. We also include a calculation for the 2 + carbon fusion and discuss a possible experimental investigation. Our results confirm direct experimental and theoretical results close to the barrier, while suggest possible 2 + mixtures in the indirect experimental data. Furthermore, our study offers an accurate view of the burning process in the somewhat unexplored low energy region.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗

DOE OSTI2020

Searching for solitons in heavy-ion reactions near the fermi energy

Solitons are special shape-conserving hydrodynamical solutions that appear in many areas of physics. Here, we explore the existence of such solutions in microscopic descriptions of the heavy ion reaction 12 C + 28 Si → 12 C*+ 7α in the range E/A = 10 – 65 MeV/u. After recognizing the centrality of the collision and time-reversibility as fundamental requirements for the presence of solitonic 12 C, we utilize the Hybrid α-Cluster model for our analysis with a novel methodology. Our results suggest soliton production for E/A = 25 – 45 MeV/u in the forward direction, with a total cross section being at least in the order of a few μb. This, apart from being encouraging for possible experimental studies, maybe connected to possible toroid states of 28 Si at low angular momenta.

Heavy ion reactions↗