Deep Learning reconstruction with uncertainty estimation for γ\gamma photon interaction in fast scintillator detectors

This article presents a physics-informed deep learning method for the quantitative estimation of the spatial coordinates of gamma interactions within a monolithic scintillator, with a focus on Positron Emission Tomography (PET) imaging. A Density Neural Network approach is designed to estimate the 2-dimensional gamma photon interaction coordinates in a fast lead tungstate (PbWO4) monolithic scintillator detector. We introduce a custom loss function to estimate the inherent uncertainties associated with the reconstruction process and to incorporate the physical constraints of the detector. This unique combination allows for more robust and reliable position estimations and the obtained results demonstrate the effectiveness of the proposed approach and highlights the significant benefits of the uncertainties estimation. We discuss its potential impact on improving PET imaging quality and show how the results can be used to improve the exploitation of the model, to bring benefits to the application and how to evaluate the validity of the given prediction and the associated uncertainties. Importantly, our proposed methodology extends beyond this specific use case, as it can be generalized to other applications beyond PET imaging.Comment: Submitted to Artificial Intelligenc

Suppression of electrical breakdown phenomena in liquid TriMethyl Bismuth based ionization detectors

Organometallic liquids provide good properties for ionization detectors. TriMethyl Bismuth (TMBi) has been proposed as a detector medium with charge and Cherenkov photon readout for Positron Emission Tomography. In this work, we present studies for the handling of TMBi at different electric fields and under different environmental conditions to find applicable configurations for the suppression of electrical breakdowns in TMBi at room temperature. A simple glass cell with two electrodes filled with TMBi was constructed and tested under different operation conditions. Working at the vapour pressure of TMBi at room temperature of about 40 mbar and electric fields of up to 20 kV/cm in presence of a small oxygen contamination we found the formation of a discharge channel in the liquid and a steady increase in the current. Further reduction of pressure by pumping caused the TMBi to boil and a spontaneous combustion. Eliminating the oxygen contamination led the TMBi under the same condition to only decompose. When operating the setup under an argon atmosphere of 1 bar we did not observe breakdowns of the electrical potential up to field strengths of 20 kV/cm. Still, in presence of a small oxygen contamination fluctuating currents in the nA range were observed, but no decomposition or combustion. We conclude from our experiments that TMBi at room temperature in a pure argon atmosphere of 1 bar remains stable against electrical breakdown at least up to electric field strengths of 20 kV/cm, presumably because the formation of gaseous TMBi was prevented.Comment: 14 page, 8 figure

Experimental status of top charge asymmetry measurements

The latest measurements of the asymmetry in the angular distributions of the $t\bar{t}$ events are reviewed. The measurements of the forward-backward asymmetry $A_{FB}$ in the $p\bar{p}$ 1.98 TeV collision at the Tevatron show some tension with the standard model calculation, while results of the measurements of the charge asymmetry $A_C$ in $pp$ collisions at 7 TeV and 8 TeV at the LHC are compatible with standard model prediction.The latest measurements of the asymmetry in the angular distributions of the $t\bar{t}$ events are reviewed. The measurements of the forward-backward asymmetry $A_{FB}$ in the $p\bar{p}$ 1.98 TeV collision at the Tevatron show some tension with the standard model calculation, while results of the measurements of the charge asymmetry $A_C$ in $pp$ collisions at 7 TeV and 8 TeV at the LHC are compatible with standard model prediction.The latest measurements of the asymmetry in the angular distributionsof the \ttbar\ events are reviewed. The measurements of the forward-backwardasymmetry \Afb\ in the \ppbar\ 1.98 TeV collisions at the Tevatronshow some tension with the Standard Model calculation, while resultsof the measurements of the charge asymmetry \Ac\ in $pp$ collisionsat 7 TeV and 8 TeV at the LHC are compatible with Standard Model predictions

Experimental status of top charge asymmetry measurements

The latest measurements of the asymmetry in the angular distributionsof the \ttbar\ events are reviewed. The measurements of the forward-backwardasymmetry \Afb\ in the \ppbar\ 1.98 TeV collisions at the Tevatronshow some tension with the Standard Model calculation, while resultsof the measurements of the charge asymmetry \Ac\ in $pp$ collisionsat 7 TeV and 8 TeV at the LHC are compatible with Standard Model predictions

Development of the fast and efficient gamma detector using cherenkov light

International audienc

Characterization of the BOLDPET optical prototype, an innovative Cherenkov detector for 511 keV γ\gamma radiation

International audienceIn the present work we describe the design, construction, and testing of the optical prototype developed for the BOLDPET project, with the objective of creating a PET detection module with high spatial and time resolution. The BOLDPET technology uses an innovative detection liquid, trimethylbismuth, for detecting 511 keV $\gamma$-quanta resulting from positron annihilation. The optical signal is exclusively produced through the Cherenkov mechanism, and the produced photons are detected using Planacon microchannel-plate photomultiplier. We achieve an excellent time resolution of 150 ps (FWHM) within a sizable detection volume measuring 55 mm x 55 mm x 25 mm. Through detailed Geant4 simulations, we examine the limiting factors affecting time resolution and explore potential avenues for improvement. Furthermore, we demonstrate the feasibility of coarse 2D localization of interactions using the optical signal alone, achieving a precision of about 5-8 mm (FWHM) within the homogeneous detection volume