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

Field science in the Railroad Era: the tools of knowledge empire in the American West, 1869-1916 Pesquisas de campo na era das ferrovias: os instrumentos do império dos conhecimentos no Oeste dos Estados Unidos, 1869-1916

Focusing on the field sciences during the late nineteenth and early twentieth centuries, this paper analyzes how railroads served as tools of knowledge empire in the American West. The political economy of this region, shaped by the rise of Populism and capitalist development with federal and state government support, provided the context for cooperation between field scientists and railroad companies. Early on, the displacement of American Indians and their concentration on reservations was intertwined with the research of the Bureau of Ethnology under John Wesley Powell. Later, railroad companies became important patrons of field research, primarily through their provision of free or reduced-fare passes for travel. This research ranged from state universities undertaking research in horticulture and irrigation engineering to metropolitan natural history museums whose field work in paleontology had cultural or symbolic value.<br>Ao analisar pesquisas de campo realizadas no final do século XIX e início do XX, o artigo mostra como as estradas de ferro foram instrumentos do império dos conhecimentos no Oeste dos Estados Unidos. A economia política da região foi modelada pela ascensão do populismo e pelo desenvolvimento do capitalismo com o apoio dos governos estaduais e federal. Criaram-se assim as condições para a cooperação entre cientistas e companhias ferroviárias. Num primeiro momento, o deslocamento dos índios e sua concentração em reservas estiveram relacionados às pesquisas do Escritório de Etnologia, então dirigido por John Wesley Powell. As companhias ferroviárias tornaram-se importantes patrocinadoras de pesquisas de campo fornecendo passagens gratuitas ou a custos reduzidos para as viagens dos cientistas, desde aqueles ligados a universidades públicas que promoviam estudos sobre horticultura e engenharia da irrigação, até museus metropolitanos de história natural, cujos trabalhos de campo em paleontologia tinham valor simbólico ou cultural