Neutron Moderation in the Oklo Natural Reactor and the Time Variation of alpha

In the analysis of the Oklo (gabon) natural reactor to test for a possible time variation of the fine structure constant alpha, a Maxwell-Boltzmann low energy neutron spectrum was assumed. We present here an analysis where a more realistic spectrum is employed and show that the most recent isotopic analysis of samples implies a non-zero change in alpha, over the last two billion years since the reactor was operating, of \Delta\alpha/\alpha\geq 4.5\times 10^{-8} (6\sigma confidence). Issues regarding the interpretation of the shifts of the low energy neutron resonances are discussed.Comment: 7 pages, 4 figures; version 2 included reference to Flambaum/Shuryak work and corrects error in abstract version three corrects a few points and adds discussion on hydrogen and impurity concentration

Properties making a chaotic system a good Pseudo Random Number Generator

We discuss two properties making a deterministic algorithm suitable to generate a pseudo random sequence of numbers: high value of Kolmogorov-Sinai entropy and high-dimensionality. We propose the multi dimensional Anosov symplectic (cat) map as a Pseudo Random Number Generator. We show what chaotic features of this map are useful for generating Pseudo Random Numbers and investigate numerically which of them survive in the discrete version of the map. Testing and comparisons with other generators are performed.Comment: 10 pages, 3 figures, new version, title changed and minor correction

Analysis of Sample Correlations for Monte Carlo Rendering

Modern physically based rendering techniques critically depend on approximating integrals of high dimensional functions representing radiant light energy. Monte Carlo based integrators are the choice for complex scenes and effects. These integrators work by sampling the integrand at sample point locations. The distribution of these sample points determines convergence rates and noise in the final renderings. The characteristics of such distributions can be uniquely represented in terms of correlations of sampling point locations. Hence, it is essential to study these correlations to understand and adapt sample distributions for low error in integral approximation. In this work, we aim at providing a comprehensive and accessible overview of the techniques developed over the last decades to analyze such correlations, relate them to error in integrators, and understand when and how to use existing sampling algorithms for effective rendering workflows.publishe

Studying the Flexibility of a BDT as a VBF di-Higgs Production Analysis Tool

Accurately analyzing the monumental amount of data sourced from high-energy particle experiments presents a herculean task. Some methods under investigation for event analysis, particularly while searching for low-probability events, are machine learning algorithms. Tyler Burch has developed a Boosted Decision Tree (BDT) to look for Vector Boson Fusion (VBF) events through di-Higgs production. VBF is a di-Higgs production process. This report investigates the performance of the BDT if given simulated collision data produced by varying the interaction constants in VBF hhjj production away from those predicted by the Standard Model. The test range will focus on 3 coupling constants—λ, cvv, and cv, governing HHH, VVHH, and VVH vertexes respectively—varying from 0 to 3 normalized to the standard model for c2v and cv and 0 to 11 for λ. This is an analysis for the ATLAS experiment at the LHC.B.S. (Bachelor of Science

Oak Ridge National Laboratory Report ORNL-2789

Report covering the development of a set of difference equations for machine solution. In addition, this report serves as user's manual for Corn Pone, which is a code for the Oracle, the Oak Ridge National Laboratory computer