Measuring the Learning from Two-Stage Collaborative Group Exams

A two-stage collaborative exam is one in which students first complete the exam individually, and then complete the same or similar exam in collaborative groups immediately afterward. To quantify the learning effect from the group component of these two-stage exams in an introductory Physics course, a randomized crossover design was used where each student participated in both the treatment and control groups. For each of the two two-stage collaborative group midterm exams, questions were designed to form matched near-transfer pairs with questions on an end-of-term diagnostic which was used as a learning test. For diagnostic test questions paired with questions from the first midterm, which took place six to seven weeks before the diagnostic test, an analysis using a mixed-effects logistic regression found no significant differences in diagnostic-test performance between the control and treatment group. For diagnostic test questions paired with questions from the second midterm, which took place one to two weeks prior to the diagnostic test, the treatment group performed significantly higher on the diagnostic-test than control.Comment: 4 pages, 1 figure, submitted to the proceedings of the 2014 Physics Education Research Conferen

Exploring the contributions of self-efficacy and test anxiety to gender differences in assessments

The observed performance difference between women and men on assessments in physics---the "gender gap"---is a significant and persistent inequity which has broad implications for the participation of women in physics. Research also shows that gender-based inequities extend to affective measures, such as self-efficacy. In this exploratory study, we report on gender disparities in self-efficacy and test anxiety and their relationship to assessment scores in our active-learning introductory physics course. Overall, gender-based differences in favour of men are observed in all our measures, with women having lower scores on measures associated with success (self-efficacy and assessment scores) and a higher score on a possibly detrimental affective factor (test anxiety). Using a multiple regression model-selection process to explore which measures may explain end-of-course Force Concept Inventory (FCI) and final exam scores, we find that the best fitting models include FCI pretest and self-efficacy as predictors, but do not include test anxiety.Comment: Accepted to the 2020 Physics Education Research Conference Proceeding

The measurement of the rare kaon decay k-plus to pi-plus, neutrino and anti-neutrino

Brookhaven National Laboratory experiment E949 was designed to search for the rare K meson decay K⁺ → π⁺ , neutrino, and anti-neutrino, a decay sensitive to physics beyond the Standard Model. While previous data analyses dealt with the high π⁺ momentum region accessible for this reaction, this thesis concentrates on the lower range between 140 and 199 MeV/c. Analysis of this low π⁺ momentum region was performed to search for additional evidence of the process K⁺ → π⁺, neutrino, and anti-neutrino. A blind analysis technique was used to avoid bias when developing the selection criteria used to suppress the competing background processes. The blind analysis technique was based on identifying background sources a priori and only examining the signal region once all selection criteria and background estimates had been finalized. The background estimates were performed using a technique known as a "bifurcation method", which relied on using two uncorrelated selection criteria to suppress each background source. The analysis of an exposure of 1.71 x 10¹² K⁺ decays resulted in an observation of three events with an estimated background of 0.927 ± 0.168(stat.)⁺³²⁰-₀.₂₃₇(sys.) events and a single event sensitivity of (4.28 ± 0.43)x 10-¹⁰. Using a likelihood method, the three candidate events observed here were combine with the previous E787 and E949 results, yielding a branching ratio of ϐ(K⁺ → π⁺, neutrino, and anti-neutrino decay of (1.73+1.15-1.05) x 10⁻¹⁰ at the 68% confidence level. This branching ratio is consistent with the prediction of the Standard Model, (0.85 ± 0.07) x 10⁻¹⁰.Science, Faculty ofPhysics and Astronomy, Department ofGraduat

Simulation and measurement of the response of the blowfish detector to low-energy neutrons

Blowfish is a highly segmented neutron detector array consisting of 88 cells filled with BC-505 liquid scintillator. The cells make up a spherical shape that covers approximately one quarter of the total solid angle of 4 pi steradians. A high-priority measurement for Blowfish is the low energy contribution to the Gerasimov-Drell-Hearn (GDH) sum rule on the deuteron, which uses circularly polarized gamma rays. The experimental data that needs to be collected are the absolute cross-sections when the gamma ray helicity and target polarization are parallel and anti-parallel. To extract absolute cross-sections from the data, it will be necessary to have characterized the efficiency of the detector.Another measurement that would benefit from the efficiency calibration is the photodistegration of deuterium, which has already been performed. This measurement used linearly-polarized gamma rays at energies of 2.6, 3.5, 4.0 and 6.0 MeV. The relative cross-sections from this measurement provide much useful information, but to extract the absolute cross-sections the Blowfish efficiency calibration is needed. This thesis presents this efficiency calibration. The efficiency calibration was done using a 252Cf source in a parallel plate ionization chamber over the energy range of 0 to 6 MeV. To determine the absolute scale of the extracted efficiency curves, an efficiency analysis and simulation of a previously characterized BC-519 liquid scintillator cell needed to be performed along with a simulation of the Blowfish detector array. The measured efficiencies were consistent with those predicted by the simulation over the desired energy range