Search Results (5 total)

An important result of physics education research is that students’ learning and success in a course is correlated with their beliefs, attitudes, and expectations regarding physics. However, it is hard to assess these beliefs for individual students, and traditional survey instruments such as the Maryland Physics Expectations Survey (MPEX) are intended to evaluate the impact of one or more semesters of instruction on an overall class and improve teaching. In this study, we investigate the possibility of using the analysis of online student discussion behavior as an indicator of an individual student’s approach to physics. These discussions are not tainted by the effects of self-reporting, and are gathered in authentic nonresearch settings, where students attempt to solve problems in the way that they believe is most efficient and appropriate. We calculate the correlation of both MPEX and student discussions with different measures of student learning, and find that on an individual base, student discussions are a stronger predictor of success than MPEX outcomes.

Within quantum molecular dynamics (QMD) simulations we demonstrate the effect of virial corrections on heavy ion reactions. Unlike in standard codes, the binary collisions are treated as nonlocal so that the contribution of the collision flux to the reaction dynamics is covered. A comparison with standard QMD simulations shows that the virial corrections lead to a broader proton distribution bringing theoretical spectra closer towards experimental values. Complementary Boltzmann-Uehling-Uhlenbeck simulations reveal that the nonlocality enhances the collision rate in the early stage of the reaction. It suggests that the broader distribution appears due to an enhanced preequilibrium emission of particles.

Significant differences in the relationships between fragment, neutron, and charged particle multiplicities were found between ¹¹²Sn+¹¹²Sn and ¹²⁴Sn+¹²⁴Sn collisions at 40 MeV/A. In this paper we explore the possibility to explain this phenomenon in the framework of percolation models, and find that the results are only reproducible in part.

Transport models have successfully described many aspects of intermediate energy heavy-ion collision dynamics. As the energies increase in these models to the ultrarelativistic regime, Lorentz covariance and causality are not strictly respected. The standard argument is that such effects are not important to final results; but they have not been seriously considered at high energies. We point out how and why these happen, how serious of a problem they may be and suggest ways of reducing or eliminating the undesirable effects.

The description of the three-nucleon system in terms of nucleon and Δ degrees of freedom is extended to allow for explicit pion production (absorption) from single dynamic Δ deexcitation (excitation) processes. This mechanism yields an energy dependent effective three-body Hamiltonian. The Faddeev equations for the trinucleon bound state are solved with a force model that has already been tested in the two-nucleon system above pion-production threshold. The binding energy and other bound-state properties are calculated. The contribution to the effective three-nucleon force arising from the pionic degrees of freedom is evaluated. The validity of previous coupled-channel calculations with explicit but stable Δ isobar components in the wave function is studied.