J. Allison | Searcharxiv

arXiv2020

Photon quantum entanglement in the MeV regime and its application in PET imaging

Positron Emission Tomography (PET) is a widely-used imaging modality for medical research and clinical diagnosis. Here we demonstrate, through detailed experiments and simulations, an exploration of the benefits of exploiting the quantum entanglement of linear polarisation between the two positron annihilation photons utilised in PET. A new simulation, which includes the predicted influence of quantum entanglement on the interaction of MeV-scale photons with matter, is validated by comparison with experimental data from a cadmium zinc telluride (CZT) PET demonstrator apparatus. In addition, a modified setup enabled the first experimental constraint on entanglement loss for photons in the MeV regime. Quantum-entangled PET offers new methodologies to address key challenges in next generation imaging. As an indication of the potential benefits, we present a simple method to quantify and remove in-patient scatter and random backgrounds using only the quantum entanglement information in the PET events.

physics.med-ph↗

arXiv2016

Implementation of a goodness-of-fit test for finding optimal concurrent radio and γ-ray pulsar light curves

Since the launch of the Fermi Large Area Telescope in 2008 the number of known $γ$-ray pulsars has increased immensely to over 200, many of which are also visible in the radio and X-ray bands. Seyffert et al. (2011) demonstrated how constraints on the viewing geometries of some of these pulsars could be obtained by comparing their observed radio and $γ$-ray light curves by eye to light curves from geometric models. While these constraints compare reasonably well with those yielded by more rigorous single-wavelength approaches, they are still a somewhat subjective representation of how well the models reproduce the observed radio and $γ$-ray light curves. Constructing a more rigorous approach is, however, made difficult by the large uncertainties associated with the $γ$-ray light curves as compared to those associated with the radio light curves. Naively applying a $χ^{2}$-like goodness-of-fit test to both bands invariably results in constraints dictated by the radio light curves. A number of approaches have been proposed to address this issue. In this paper we investigate these approaches and evaluate the results they yield. Based on what we learn, we implement our own version of a goodness-of-fit test, which we then use to investigate the behaviour of the geometric models in multi-dimensional phase space.

astro-ph.HE↗