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C. A. Ogilvie

Publications and source records attributed to C. A. Ogilvie.

10 recordsLinked to original sources
arXiv2008

Impact of Context-Rich, Multifaceted Problems on Students' Attitudes Towards Problem-Solving

Most students struggle when faced with complex and ill-structured tasks because the strategies taught in schools and universities simply require finding and applying the correct formulae or strategy to answer well-structured, algorithmic problems. For students to develop their ability to solve ill-structured problems, they must first believe that standardized procedural approaches will not always be sufficient for solving ill-structured engineering and scientific challenges. In this paper we document the range of beliefs university students have about problem-solving. Students enrolled in a physics course submitted a written reflection both at the start and the end of the course on how they solve problems. We coded approximately 500 of these reflections for the presence of different problem-solving approaches. At the start of the semester over 50% of the students mention in written reflections that they use Rolodex equation matching, i.e. they solve problems by searching for equations that have the same variables as the knowns and unknowns. We then describe the extent to which students' beliefs about physics problem-solving change due to their experience throughout a semester with context-rich, multifaceted problems. The frequency of strategies such as the Rolodex method reduces only slightly by the end of the semester. However, there is an increase in students describing more expansive strategies within their reflections. In particular there is a large increase in describing the use of diagrams, and thinking about concepts first. Hence the use of context-rich, multi-faceted problems positively impacts students' attitude towards problem-solving.

physics.ed-ph↗
arXiv2007

Understanding Student Pathways in Context-rich Problems

In this paper we investigate the extent to which students' problem-solving behaviors change as a result of working on multi-faceted, context-rich problems. During the semester, groups of two to three students work on several problems that require more than one concept and hence cannot be readily solved with simple plug-and-chug strategies. The problems are presented to students in a data-rich, online problem-solving environment that tracks which information items are selected by students as they attempt to solve the problem. The students also complete a variety of tasks, such as entering their qualitative analysis into an online form. Students are not constrained to complete these tasks in any order. As they gain more experience in solving multifaceted physics problems, the student groups show some progression towards expert-like behavior: earlier qualitative analysis and more selective requests for information. However, there is room for more improvement as approximately half of the groups still complete the qualitative analysis task towards the end of the solution instead of earlier when it would be most useful to their work.

physics.ed-ph↗
arXiv2004

Production of phi Mesons in Au+Au Collisions at 11.7 A GeV/c

We report on a measurement of phi-meson production in Au+Au collisions at a beam momentum of 11.7 A GeV/c by Experiment E917 at the AGS. The measurement covers the midrapidity region 1.2 < y < 1.6. Transverse-mass spectra and the rapidity distribution are presented as functions of centrality characterized by the number of participant projectile nucleons. The yield of phi's per participant projectile nucleon increases strongly in central collisions in a manner similar to that observed for kaons.

nucl-ex↗
arXiv2001

Review of Nuclear Reactions at the AGS

Results from p+A and A+A collisions from the beam energies 2-18 AGeV/c are reviewed with emphasis on the properties of dense hadronic matter, and its implications for claims that a new state of matter has been formed at the SPS.

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arXiv2001

Baryon Rapidity Loss in Relativistic Au+Au Collisions

An excitation function of proton rapidity distributions for different centralities is reported from AGS Experiment E917 for Au+Au collisions at 6, 8, and 10.8 GeV/nucleon. The rapidity distributions from peripheral collisions have a valley at midrapidity which smoothly change to distributions that peak at midrapidity for central collisions. The mean rapidity loss increases with increasing beam energy, whereas the fraction of protons consistent with isotropic emission from a thermal source at midrapidity decreases with increasing beam energy.

nucl-ex↗
arXiv2001

Antilambda production in Au+Au collisions at 11.7 A GeV/c

We present results from Experiment E917 for antilambda and antiproton production in Au+Au collisions at 11.7 A GeV. We have measured invariant spectra and yields for both species in central and peripheral collisions. We find that the antilambda/antiproton ratio near mid-rapidity increases from 0.26+0.19-0.15 in peripheral collisions to 3.6+4.7-1.8 in central collisions, a value that is substantially larger than current theoretical estimates.

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arXiv1999

Comparison of Strangeness Production between A+A and p+p Reactions from 2 to 160 AGeV

The measured K$^+/π^+$ ratios from heavy-ion reactions are compared with the K$^+/π^+$ ratios from p+p reactions over the energy range 2-160 AGeV. The K/$π$ enhancement in heavy-ion reactions is largest at the lower energies, consistent with strangeness production in secondary scattering becoming relatively more important than initial collisions near the kaon production threshold. The enhancement decreases steadily from 4 to 160 AGeV, suggesting that the same enhancement mechanism of hadronic rescattering and decay of strings may be applicable over this full energy range. Based on existing data, the mid-rapidity K$^+/π^+$ ratio is predicted to be $0.27\pm0.05$ for the forthcoming Pb+Pb reactions at 40 AGeV/c.

nucl-th↗
arXiv1998

Au+Au Reactions at the AGS: Experiments E866 and E917

Particle production and correlation functions from Au+Au reactions have been measured as a function of both beam energy (2-10.7AGeV) and impact parameter. These results are used to probe the dynamics of heavy-ion reactions, confront hadronic models over a wide range of conditions and to search for the onset of new phenomena.

nucl-ex↗
arXiv1996

Universality of Spectator Fragmentation at Relativistic Bombarding Energies

Multi-fragment decays of 129Xe, 197Au, and 238U projectiles in collisions with Be, C, Al, Cu, In, Au, and U targets at energies between E/A = 400 MeV and 1000 MeV have been studied with the ALADIN forward-spectrometer at SIS. By adding an array of 84 Si-CsI(Tl) telescopes the solid-angle coverage of the setup was extended to θ_lab = 16 degree. This permitted the complete detection of fragments from the projectile-spectator source. The dominant feature of the systematic set of data is the Z_bound universality that is obeyed by the fragment multiplicities and correlations. These observables are invariant with respect to the entrance channel if plotted as a function of Z_bound, where Z_bound is the sum of the atomic numbers Z_i of all projectile fragments with Z_i \geq 2. No significant dependence on the bombarding energy nor on the target mass is observed. The dependence of the fragment multiplicity on the projectile mass follows a linear scaling law. The reasons for and the limits of the observed universality of spectator fragmentation are explored within the realm of the available data and with model studies. It is found that the universal properties should persist up to much higher bombarding energies than explored in this work and that they are consistent with universal features exhibited by the intranuclear cascade and statistical multifragmentation models. PACS numbers: 25.70.Mn, 25.70.Pq, 25.75.-q

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