Event-by-event study of prompt neutrons from 239Pu(n,f)

Employing a recently developed Monte Carlo model, we study the fission of 240Pu induced by neutrons with energies from thermal to just below the threshold for second chance fission. Current measurements of the mean number of prompt neutrons emitted in fission, together with less accurate measurements of the neutron energy spectra, place remarkably fine constraints on predictions of microscopic calculations. In particular, the total excitation energy of the nascent fragments must be specified to within 1 MeV to avoid disagreement with measurements of the mean neutron multiplicity. The combination of the Monte Carlo fission model with a statistical likelihood analysis also presents a powerful tool for the evaluation of fission neutron data. Of particular importance is the fission spectrum, which plays a key role in determining reactor criticality. We show that our approach can be used to develop an estimate of the fission spectrum with uncertainties several times smaller than current experimental uncertainties for outgoing neutron energies up to 2 MeV.Comment: 17 pages, 20 figure

Empirical Study of Simulated Two-planet Microlensing Event

We undertake the first study of two-planet microlensing models recovered from simulations of microlensing events generated by realistic multi-planet systems in which 292 planetary events including 16 two-planet events were detected from 6690 simulated light curves. We find that when two planets are recovered, their parameters are usually close to those of the two planets in the system most responsible for the perturbations. However, in one of the 16 examples, the apparent mass of both detected planets was more than doubled by the unmodeled influence of a third, massive planet. This fraction is larger than, but statistically consistent with, the roughly 1.5% rate of serious mass errors due to unmodeled planetary companions for the 274 cases from the same simulation in which a single planet is recovered. We conjecture that an analogous effect due to unmodeled stellar companions may occur more frequently. For seven out of 23 cases in which two planets in the system would have been detected separately, only one planet was recovered because the perturbations due to the two planets had similar forms. This is a small fraction (7/274) of all recovered single-planet models, but almost a third of all events that might plausibly have led to two-planet models. Still, in these cases, the recovered planet tends to have parameters similar to one of the two real planets most responsible for the anomaly.Comment: 21 pages, 9 figures, 2 tables; submitted to ApJ; for a short video introducing the key results, see https://www.youtube.com/watch?v=qhK4a6sbfO

Event Study Tests: A brief survey

In this paper, I describe some of the main parametric and non-parametric tests used in event studies to assess the significance of abnormal returns or changes in variance of returns.Event Studies

First event-by-event fluctuation studies in Pb-Pb collisions at LHC energy by the ALICE experiment

The presence of the phase transition can manifest itself by the characteristic behavior of several observables which may vary dramatically from one event to the other. Thus, the study of various conserved quantities on an event-by-event basis offers the possibility to study the phase transition and the nature of high density matter. The ALICE experiment is well suited for precise event-by-event measurements of various quantities. In this article, the event-by-event fluctuations of mean transverse momentum and net-charge distributions as measured by the ALICE experiment are presented

Methods to study event-by-event fluctuations in the NA61/SHINE experiment at the CERN SPS

Theoretical calculations locate the critical point of strongly interacting matter (CP) at energies accessible at the CERN SPS. Event-by-event transverse momentum and multiplicity fluctuations are considered as one of the most important tools to search for the CP. Pilot studies of the energy dependence and the system size dependence of both $p_T$ and multiplicity fluctuations were performed by the NA49 experiment. The NA61/SHINE ion program is a continuation of these efforts. After briefly recalling the essential NA49 results on fluctuations we will discuss the technical methods (removing Non-Target interactions) which we plan to apply for future transverse momentum and multiplicity fluctuation analyses.Comment: Proceedings of CPOD 2010, 23-29 August, JINR, Dubn

A Study of the Di-Hadron Angular Correlation Function in Event by Event Ideal Hydrodynamics

The di-hadron angular correlation function is computed within boost invariant, ideal hydrodynamics for Au+Au collisions at $\sqrt{s}_{NN}=200$ GeV using Monte Carlo Glauber fluctuating initial conditions. When $0<p_T< 3$ GeV, the intensity of the flow components and their phases, $\left\{v_n, \Psi_n \right \}$ ($n=2,3$), are found to be correlated on an event by event basis to the initial condition geometrical parameters $\left\{\varepsilon_{2,n}, \Phi_{2,n} \right \}$, respectively. Moreover, the fluctuation of the relative phase between trigger and associated particles, $\Delta_n =\Psi_n^t - \Psi_n^a$, is found to affect the di-hadron angular correlation function when different intervals of transverse momentum are used to define the trigger and the associated hadrons.Comment: 15 pages, 10 figures; typos fixed, added reference

Empirical Correlates of Event Types - A priming study

Event types have been widely addressed in linguistics literature, but have received little attention in psycholinguitics, neurolinguistics and computational linguistics research. This thesis dissertation explores the nature of event types from a cognitive point of view: many descriptions and diagnostics on event types are available, but few studies have dealt with the problem of how event types are represented and processed in the mental lexicon. An important prerequisite for this sort of research is the building of a corpus of stimuli that meets our needs (web-based pre-tests were run to test the reliability of the stimuli, which should be balanced to control the variables known to aect processing costs) and an analysis of pre-existing literature in experimental psycholinguistics of event types. Our main concern was to explore new experimental settings in verb semantics psycholinguistics and to adapt them to this specic type of investigation: the choice of the method was narrowed down to the semantic priming paradigm, although the set of stimuli could also be suitable for other experimental settings, such as reading-time studies. The semantic priming paradigm was exploited to contrast processing effects on achievement verbs and activity verbs, which dier with respect to two superordinate features: durativity and resultativity. A series of priming experiments were run to explore differences and interactions between such features and the tense morphology and to evaluate the dierent contribution of the experimental setting in the observation and measurement of the effect: experiment 1 and experiment 2 followed a similar design and contrasted the eects of different neutral primes; experiment 3 focused on the interaction between event types and Italian tense morphology