Abstract
The speed-up in program running time is investigated for problems of parameter estimation with nested sampling Monte Carlo methods. The example used in this study is to extract a polarisation observable from event-by-event data from meson photoproduction reactions. Various implementations of the basic algorithm were compared, consisting of combinations of single threaded versus multi-threaded, and CPU versus GPU versions. These were implemented in OpenMP and OpenCL. For the application under study, and with the number of events as used in our work, we find that straightforward multi-threaded CPU OpenMP coding gives the best performance; for larger numbers of events, OpenCL on the CPU performs better. The study also shows that there is a “break-even” point of the number of events where the use of GPUs helps performance. GPUs are not found to be generally helpful for this problem, due to the data transfer times, which more than offset the improvement in computation time.
Highlights
Many data analysis tasks in nuclear and particle physics are parameter estimation problems
The spotlight is currently on general purpose graphical processor unit (GPGPU) computing, it must be remembered that all programs and algorithms will include some amount of sequential code, even if it exists solely to execute kernel functions or perform or some standard initialisations
The first tests were performed to determine the optimal number of threads using each data set on the three implementations that allowed for multithreading (OpenCL-CPU, OpenCL-GPU and OpenMP)
Summary
Many data analysis tasks in nuclear and particle physics are parameter estimation problems. Lewis et al / Nuclear Instruments and Methods in Physics Research A 785 (2015) 105–109 to determine the photon beam asymmetry, Σ, which is the difference divided by the sum of cross-sections for the two states of photon linear polarisation This is achieved by measuring the distribution of mesons as a function of azimuthal angle φ, which is the angle between the reaction plane and the direction of the photon's linear polarisation (E-vector). In a with a range of Eγ real and experiment, θ⋆CM, but the data would be sorted into bins ranges would be minimised to extract the maximum physics information from the variation of observables as functions of Eγ and θ⋆CM This example could be applied to any reaction in which the photon beam asymmetry is to be determined. We use a two-body phase-space generator where the azimuthal distributions of the mesons are modulated according to Eq (1)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
