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J. Ives

Publications and source records attributed to J. Ives.

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Constraints From Simulation Improve Experiential Outcomes in Laboratory Environment

In a first-year physics inquiry lab, pairs of students were randomly assigned to study pendulum motion using either a physical apparatus or a computer simulation. The experiment required detecting a ~1% difference in period between pendulums released at 10$^\circ$ and 20$^\circ$. This is the subtle failure of the small angle approximation and a goal that demands iteratively refined, high-precision measurements. Students using the simulation achieved significantly more reproducible timing measurements across all rounds of data collection and, by the third round, had also adopted more effective data collection strategies overall. As a result, 78% of simulation groups met the precision threshold required to identify the model failure, compared with 52% of physical apparatus groups. We attribute these outcomes primarily to a specific simulation constraint: students were required to use the simulation's built-in timer, which forced them to decouple pendulum release from the start of timing. This prevented students from pursuing a reaction-time-limited synchronization strategy that often traps users of physical apparatus in a low-precision measurement dead end. A post-lab survey further shows that students using simulations were more confident in their results than those who instead used a physical pendulum, as well as preferred greater use of simulations in future labs. These findings suggest that carefully designed simulation constraints can guide students toward productive experimental strategies while preserving their investigative autonomy.

physics.ed-ph

Search for the rare decay $K^+\toμ^+ν\barνν$

Evidence of the $K^+\toμ^+ν\barνν$ decay was searched for using E949 experimental data with an exposure of $1.70\times 10^{12}$ stopped kaons. The data sample is dominated by the backgrond process $K^+\toμ^+ν_μγ$. An upper limit on the decay rate $Γ(K^+\toμ^+ν\barνν)< 2.4\times 10^{-6}Γ(K^+\to all)$ at 90% confidence level was set assuming the Standard Model muon spectrum. The data are presented in such a way as to allow calculation of rates for any assumed $μ^+$ spectrum.

hep-ex

Search for heavy neutrinos in $K^+\toμ^+ν_H$ decays

Evidence of a heavy neutrino, $ν_H$, in the $K^+\toμ^+ν_H$ decays was sought using the E949 experimental data with an exposure of $1.70\times 10^{12}$ stopped kaons. With the major background from the radiative $K^+\toμ^+ν_μγ$ decay understood and suppressed, upper limits (90% C.L.) on the neutrino mixing matrix element between muon and heavy neutrino, $|U_{μH}|^2$, were set at the level of $10^{-7}$ to $10^{-9}$ for the heavy neutrino mass region 175 to 300 MeV/$c^2$.

hep-ex

Study of the decay K+ => pi+,nu,nubar in the momentum region 140<Ppi<199 MeV/c

Experiment E949 at Brookhaven National Laboratory has observed three new events consistent with the decay K+ => pi+,nu,nubar in the pion momentum region 140 < P_pi < 199 MeV/c in an exposure of 1.71e12 stopped kaons with an estimated total background of 0.93+-0.17(stat.)+0.32-0.24(syst.) events. This brings the total number of observed K+ => pi+,nu,nubar events to seven. Combining this observation with previous results, assuming the pion spectrum predicted by the standard model, results in a branching ratio of (1.73+1.15-1.05)e-10. An interpretation of the results for alternative models of the decay K^ => pi+,nothing is also presented.

hep-ex