Highly-parallelized simulation of a pixelated LArTPC on a GPU

The rapid development of general-purpose computing on graphics processing units (GPGPU) is allowing the implementation of highly-parallelized Monte Carlo simulation chains for particle physics experiments. This technique is particularly suitable for the simulation of a pixelated charge readout for time projection chambers, given the large number of channels that this technology employs. Here we present the first implementation of a full microphysical simulator of a liquid argon time projection chamber (LArTPC) equipped with light readout and pixelated charge readout, developed for the DUNE Near Detector. The software is implemented with an end-to-end set of GPU-optimized algorithms. The algorithms have been written in Python and translated into CUDA kernels using Numba, a just-in-time compiler for a subset of Python and NumPy instructions. The GPU implementation achieves a speed up of four orders of magnitude compared with the equivalent CPU version. The simulation of the current induced on 10^3 pixels takes around 1 ms on the GPU, compared with approximately 10 s on the CPU. The results of the simulation are compared against data from a pixel-readout LArTPC prototype

The DUNE far detector vertical drift technology. Technical design report

DUNE is an international experiment dedicated to addressing some of the questions at the forefront of particle physics and astrophysics, including the mystifying preponderance of matter over antimatter in the early universe. The dual-site experiment will employ an intense neutrino beam focused on a near and a far detector as it aims to determine the neutrino mass hierarchy and to make high-precision measurements of the PMNS matrix parameters, including the CP-violating phase. It will also stand ready to observe supernova neutrino bursts, and seeks to observe nucleon decay as a signature of a grand unified theory underlying the standard model. The DUNE far detector implements liquid argon time-projection chamber (LArTPC) technology, and combines the many tens-of-kiloton fiducial mass necessary for rare event searches with the sub-centimeter spatial resolution required to image those events with high precision. The addition of a photon detection system enhances physics capabilities for all DUNE physics drivers and opens prospects for further physics explorations. Given its size, the far detector will be implemented as a set of modules, with LArTPC designs that differ from one another as newer technologies arise. In the vertical drift LArTPC design, a horizontal cathode bisects the detector, creating two stacked drift volumes in which ionization charges drift towards anodes at either the top or bottom. The anodes are composed of perforated PCB layers with conductive strips, enabling reconstruction in 3D. Light-trap-style photon detection modules are placed both on the cryostat's side walls and on the central cathode where they are optically powered. This Technical Design Report describes in detail the technical implementations of each subsystem of this LArTPC that, together with the other far detector modules and the near detector, will enable DUNE to achieve its physics goals

Relationship between illness representation and self-efficacy

Aim.  This paper reports a patient survey exploring the possible relationship between illness perception and self-efficacy following a cardiac event, and the implications this could have for nursing practice. Background.  Cardiac rehabilitation guidelines endorse the need to improve psychological care; suggesting that individualized support will improve the effectiveness of cardiac rehabilitation. Surveys, however, continue to identify that psychosocial factors are poorly assessed. Illness representation and self-efficacy are two prominent research approaches that have been developed as separate foci for the treatment of patients. Method.  A cross-sectional survey with patients diagnosed with either myocardial infarction or angina over an 8-month period in two hospitals. The Illness Perception Questionnaire, General Self-Efficacy Questionnaire, Cardiac Diet Self-efficacy Instrument and Cardiac Exercise Self-efficacy Instrument were used, alongside two specifically-designed scales: the Diet Outcome Expectation and Exercise Outcome Expectation Scales. Results.  The results indicate that there is a significant relationship between illness perception and self-efficacy. The greater patients’ perceived consequences of the heart condition, the lower was the general self-efficacy available to cope with the condition. Further, the longer the perceived time the condition will affect the patient, the higher the specific self-efficacy to maintain a change of diet or exercise regime. Conclusion.  The findings identify that, in the initial phase of recovery, nursing practice needs to focus on the key variables of ‘consequence’ and ‘timeline’ in order to increase patients’ confidence in their ability to cope (self-efficacy)