2,200 research outputs found
A new Monte Carlo muon generator for cosmic-ray muon applications
No full textCosmic rays, thanks to their ubiquity and high penetration capability, have been successfully used in scientific research ever since their discovery. As soon as their knowledge improved, applications in the civil/environmental field were also developed: muon radiography (or muography, based on the flux attenuation) and muon tomography (based on the scattering angle) have been used to study the inner structure of volcanoes, to seek hidden rooms in Egyptian pyramids, to search for heavy metals in containers, and so on. And besides these imaging techniques, cosmic ray muons are also widely used for detector testing and alignment practically in every Nuclear Physics or Particle Physics experiment. Since most of these applications are sensitive to the angular and momentum distribution of cosmic muons, an accurate modelling of these distributions is a key feature for any generation tool conceived to simulate the cosmic muon flux. This can make the generator quite time-consuming, which is a strong limit when one needs to reach high statistics or to study large structures. A new Monte Carlo generator for cosmic-ray muons, named Efficient COsmic MUon Generator (EcoMug for short), especially designed to be fast (≳ 10^5 muons generated per second on a standard machine) without losing accuracy, is presented here. It is written as a header-only C++11 library, ready to be integrated into whatever C++ code, in particular C++ code based on Geant4 simulation tool. By default, EcoMug relies on a simple and effective parametrisation of the experimental data of cosmic ray differential flux at sea level, taken from the literature, but the library is written in such a way that every user can easily replace it with his own user-defined parametrisation. Unlike other tools, EcoMug is able to generate muons from different kind of surfaces (plane, cylinder and half-sphere), while keeping the correct angular and momentum distribution of generated tracks inside a fiducial volume. This allows to optimise the generation surface according to the system under study, and leads to a further improvement of the overall simulation efficiency. In this contribution we will present the main features of EcoMug, starting from its mathematical foundation, and eventually showing some interesting applications
EcoMug: An Efficient COsmic MUon Generator for cosmic-ray muon applications
No full textApplications of cosmic-ray (CR) muons have grown in numbers in the last decade. Measurements of flux attenuation (radiography) and scattering angles (tomography) of CR muons have been successfully applied to the inspection or monitoring of large natural and civil structures, to the search for heavy metals in container and trucks, to the control of nuclear wastes, and much more. In the present work, a new Monte Carlo generator of CR muons, called EcoMug and specifically designed for muon radiography and tomography applications, is presented. It is a header-only C++11 library, based on a parametrization of experimental data. Unlike other tools, EcoMug gives the possibility of generating from different surfaces (plane, cylinder and half-sphere), while keeping the correct angular and momentum distribution of generated tracks. For example, this flexibility allows for a very efficient generation of nearly horizontal muons, of great interest in many muon radiography and tomography applications, by using cylindrical or half-spherical generation surfaces. Finally, EcoMug also allows the generation of CR muons according to user-defined parametrizations of their differential flux. Main features of EcoMug, its mathematical foundation, as well as applications to selected study cases are presented
Cultural heritage investigations using cosmic muons
No full textCosmic rays are a constant, free source of radiation that can be exploited in various ways to probe heavy and extended objects. Analyzed with proper detection systems, they can produce radiographic as well as tomographic images of bulky materials. Several applications have been proposed, in particular in the domain of security checks, and some are presently fielded for routine use. In this paper, cosmic muon technology is presented, and its possible use in the field of cultural heritage is described
Reliability Of Functional Connectivity Measures In Resting-State Test-Retest FMRI Data
No full textThe statistical link between spontaneous fluctuations occurring in different pans of the brain can provide insights into its functional organization. Here, we used high-quality resting-state IMRI (rs-fMRI) data acquired with a test-retest paradigm to assess the reliability of several functional connectivity (IC) metrics, some of which rarely used in the current literature. After applying time/frequency methods to generate EC matrices, we restricted our focus on individual edges through different statistical measures, including but not limited to the intraclass correlation coefficient (ICC). We found that full correlation and magnitude square coherence yielded more reproducible measurements than the other metrics, as revealed by ICC values. These results have important implications when choosing metrics for quantifying FC in rs-fMRI studies, adding novel information to the current panorama of information on the test-retest reliability topic
Muography of different structures using muon scattering and absorption algorithms
No full textIn recent decades, muon imaging has found a plethora of applications in many fields. This technique succeeds to infer the density distribution of big inaccessible structures where conventional techniques cannot be used. The requirements of different applications demand specific implementations of image reconstruction algorithms for either multiple scattering or absorption-transmission data analysis, as well as noise-suppression filters and muon momentum estimators. This paper presents successful results of image reconstruction techniques applied to simulated data of some representative applications. In addition to well-known reconstruction methods, a novel approach, the so-called μCT, is proposed for the inspection of spent nuclear fuel canisters. Results obtained based on both μCT and the maximum-likelihood expectation maximization reconstruction algorithms are presented.This article is part of the Theo Murphy meeting issue 'Cosmic-ray muography'
Robot-assisted laparoscopic prostatectomy: An economic analysis for decision-making in a university hospital of Northern Italy
No full textBackground: Robotic Assisted Radical Prostatectomy (RALP) is one of the most expensive urological innovations. Prices of the “Da Vinci System” range from € 761,105 to € 1,902,762 for each unit, without taking into account the cost of maintenance and the use of additional devices. We evaluated outcomes, and costs retrospectively, comparing RALP to open retro-pubic radical prostatectomy (RRP) performed in our hospital between December 2009 and December 2010. Methods: We compared 53 RALPs, and 50 RRPs in terms of costs, and clinical outcomes. We also implemented a Break Even Analysis in order to evaluate if the public reimbursement covered the total cost of RALP. Results: According to our analysis, RALP showed lower hospitalization (p < 0.0001), higher early continence rate (p < 0.0001), better potency rate in nerve sparing procedures (p < 0.0142), and required no transfusions. Excluding the cost of purchasing and maintenance, single case costs were € 6,046.08 for RALP and € 4,834.11 for RRP, respectively. Considering the affordability of the technology, the point where the total revenue is sufficient to cover the total costs is an average of 60 cases performed per year, only in presence of additional reimbursement. ConclusionS: Although our clinical analysis shows better results in favour of RALP, the economical analysis shows that RALP's costs are consistently higher than RRP. Considering also the purchasing costs, we demonstrated that the health gain of the technology does not necessarily offset the higher costs, even in a large, university hospital (1,000 beds)
First results on material identification and imaging with a large-volume muon tomography prototype
No full textThe muon tomography technique, based on the multiple Coulomb scattering of cosmic ray muons, has been proposed recently as a tool to perform non-destructive assays of large volume objects without any radiation hazard. In this paper we discuss experimental results obtained with a scanning system prototype, assembled using two large area CMS Muon Barrel drift chambers. The capability of the apparatus to produce 3D images of objects and to classify them according to their density are presented. We show that the absorption of low momentum muons in the scanned objects produces an underestimate of their scattering density, making more difficult the discrimination of materials heavier than lead
Securing the metal recycling chain for the steel industry by detecting orphan radioactive sources in scrap metal
No full textExperimental tests are reported for the detection of the heavy metal shielding of orphan sources hidden inside scrap metal by using a recently developed muon tomography system. Shielded sources do not trigger alarm in radiation portal commonly employed at the entrance of steel industry using scrap metal. Future systems integrating radiation portals with muon tomography inspection gates will substantially reduce the possibility of accidental melting of radioactive sources securing the use of recycled metal. © 2010 American Institute of Physics
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