arXiv subjects

Roger John Barlow

Publications and source records attributed to Roger John Barlow.

3 recordsLinked to original sources

arXiv2022

Calculations of neutron fluxes and isotope conversion rates in a thorium-fuelled MYRRHA reactor, using GEANT4 and MCNPX, Nuclear Engineering and Design

Neutronics calculations have been performed of the MYRRHA ADS Reactor with a thorium-based fuel mixture, using the simulation programs MCNPX (Waters, 2002) and Geant4 (Agostinelli, 2003). Thorium is often considered for ADS systems, and this is the first evaluation of the possibilities for thorium based fuels using a reactor design which has been developed in detail. It also extends the application of the widely-used Geant4 program to the geometry of MYRRHA and to thorium. An asymptotic 232Th/233U mixture is considered, together with the standard MOX fuel and a possible 232Th/MOX starter. Neutron fluxes and spectra are calculated at several regions in the core: fuel cells, IPS cells and the two (Mo and Ac) isotope production cells. These are then used for simple calculations of the fuel evolution and of the potential for the incineration of minor actinide waste. Results from the two programs agree and support each other and show that the thorium fuel is viable, and has good evolution/breeding properties, and that minor actinide incineration, though it will not take place on a significant scale, will be demonstrable.

physics.acc-ph↗

arXiv2021

Practical Statistics for Particle Physics

This is the write-up of a set of lectures given at the Asia Europe Pacific School of High Energy Physics in Quy Nhon, Vietnam in September 2018, to an audience of PhD students in all branches of particle physics They cover the different meanings of 'probability', particularly frequentist and Bayesian, the binomial, Poisson and Gaussian distributions, hypothesis testing, estimation, errors (including asymmetric and systematic errors) and goodness of fit. Several different methods used in setting upper limits are explained, followed by a discussion on why 5 sigma are conventionally required for a 'discovery'.

physics.data-an↗

arXiv2020

Combining Experiments with Systematic Errors

We consider fits to two or more datasets for which results from the sa me experiment share a common systematic uncertainty in addition to their individ ual statistical errors. This is important in extracting the maximum information from a set of similar bu t different experiments (or the same experiment under different conditions) an alysing similar but different datasets, as happens at the LHC and other particle colliders. There are two techniques in use: using the full matrix and using extra paramneters, and we show, for a completely general fit, that for an addit ive uncertainty they are in principle equivalent even though in practice the det ails differ. For a multiplicative error the matrix fit is equivalent to the extra parameter fit if the factor is applied to the data points but not if it is applied to the function: the former leads to biassed estimates and the latter avoids them.

physics.data-an↗