Muon radiography for the safety and safeguarding of nuclear material

Muon radiography is an imaging technology based on the detection of muons of cosmic origin. Muons are able to penetrate deeply into matter and are a free source available 24h. They can be used for security and safeguards in the management of nuclear material. An example is the inspection of heavily shielded containers, such as nuclear fuel storage casks, to verify their contents in case of loss of continuity of knowledge or to image their contents if it is unknown. Muons can also be applied for subsurface investigation, providing a competitive or alternative methodology to classical prospecting methods. They can be used to study the geologic conditions of a deposit area (before construction and over time), to map empty underground structures (tunnels, shafts) or to monitor any unauthorized excavations for illegal access. This article will give a brief review of the state of the art, with some key examples

A Borehole Muon Telescope for Underground Muography

Radiographic imaging with muons by absorption, also called Muon Radiography or Muography, is a methodology based on the characteristic of the matter to be crossed by high energy muons. This physical property allows muons to pass through the material with a measurable degree of absorption depending on the density of the material. Muon Radiography applies to several different situations and is particularly suitable for investigating subsoil of civil or archaeological interest. This kind of applications needs the muon detector to be installed below the target region. A novel borehole cylindrical detector has been built and tested for use in harsh conditions and for limited space installations. It is based on the past expertise with scintillator detectors and is composed of two types of scintillating elements, bar-shaped and arcshaped. Due to its size, it can be easily installed in drilled holes of 25 cm in diameter or more, typically economical to make. Here, we describe the idea, commissioning, and some preliminary results

Muon Radiography Investigations in Boreholes with a Newly Designed Cylindrical Detector

Muons are constantly produced in cosmic-rays and reach the Earth surface with a flux of about 160 particles per second per square meter. The abundance of muons with respect to other cosmic particles and their capability to cross dense materials with low absorption rate allow them to be exploited for large scale geological or human-made object imaging. Muon radiography is based on similar principles as X-ray radiography, measuring the surviving rate of muons escaping the target and relating it to the mass distribution inside the object. In the course of decades, after the first application in 1955, the methodology has been applied in several different fields. Muography allows us to measure the internal density distribution of the investigated object, or to simply highlight the presence of void regions by observing any excess of muons. Most of these applications require the detector to be installed below the rock being probed. In case that possible installation sites are not easily accessible by people, common instrumentation cannot be installed. A novel borehole cylindrical detector for muon radiography has been recently developed to deal with these conditions. It has been realized with a cylindrical geometry to fit typical borehole dimensions. Its design maximizes the geometrical acceptance, minimizing the dead spaces by the use of arc-shaped scintillators. The details of the construction and preliminary results of the first usage are described in this paper

Muography applied to nuclear waste storage sites

Legacy storage sites for nuclear waste can pose a serious environmental problem. In fact, since certain sites date from the middle of the last century when safety protocols had not been properly established and strict bookkeeping was not enforced, a situation has evolved where the content of storage silos is basically known only with a large uncertainty both on quantity and quality. At the same time maintenance work on old storage structures is becoming ever more urgent and yet this work requires exactly that information which is now lacking on the type of waste that was stored inside. Because of the difficulty in accessing the storage silos and the near impossibility of making visual inspections inside, techniques have to be developed which can determine the presence or absence of heavy elements (i.e. uranium) within the structures. Muography is a very promising technique which could allow the survey of previously inaccessible structures. We have begun an evaluation performing feasibility studies using simulations based on real case scenarios. This paper will outline the storage site scenarios and then present some of the results obtained from the Monte Carlo simulations

numerical evaluation of the applicability of steady test bench swirl ratios to diesel engine dynamic conditions

Engine coherent flow structures such as swirl and tumble motions are key factors for the combustion process due to their capability to rise turbulence levels and enhance mixing which, in turns, severely influence both fuel efficiency and pollutant emissions. Automotive industry has therefore put great efforts over the last decades in evaluating air flow during induction stroke and air flow within the cylinder. Nowadays swirl and tumble motion characterizing a specific cylinder head are evaluated experimentally at design stage mainly using stationary flow benches. Such tests allow characterizing each head prototype using non-dimensional parameters like swirl and tumble ratios and, finally, to compare the different designs. In the present work the authors focused their attention on the swirl ratio characterization, firstly reviewing the two main methodologies for evaluating such parameter and more precisely the AVL and the Ricardo ones. A numerical method is then proposed in order to reproduce the stationary test bench with the final goal to develop a fast and accurate virtual test bench for cylinder head design. Simulations have been carried out on different VM Motori engine heads for which experimental data were available. The comparison between computational and experimental swirl ratios allowed to evaluate the suitability of using a virtual test bench as alternative or complementary to experiments. These results widened the understanding of the swirl fluid-dynamics and suggested that care must be taken when comparing duct designs having no geometrical similarity. Finally dynamic simulations have been performed for the head prototypes in order to compute the engine swirl in realistic conditions and to compare it with the steady bench results. This allowed evaluating the capability of the two different "static" swirl ratio definition (AVL/Ricardo) in correctly estimating real engine swirl. © 2015 The Authors. Published by Elsevier Ltd

Climatic and anthropogenic factors explain the variability of Fagus sylvatica treeline elevation in fifteen mountain groups across the Apennines

Abstract Background Fagus sylvatica forms the treeline across the Apennines mountain range, with an average elevation of 1589 m a.s.l. Previous studies evidenced that the current position of the treeline in the Apennines is heavily depressed as a result of a complex interaction between climatic factors and the past human pressure. In this study we correlated treeline elevation in the fifteen major mountain groups in the Apennines with selected climatic, geomorphological, and human disturbance variables in order to investigate in detail the site-specific features affecting the current treeline distribution. Results Treeline elevation was lowest in the North Italy (Apuan Alps), while the highest treeline was found in Central Italy (Simbruini). An absolute maximum treeline elevation of F. sylvatica exceeding 2000 m a.s.l. was found on 13 mountain peaks in Central and Southern Italy. Noteworthy, treeline elevation was largely lower on warmer south-facing slopes compared to northern slopes, with values several hundred meters lower in the Gran Sasso and Velino-Sirente. Although the causes of this pattern are still unknown, we argue that treeline elevation on south-facing slopes may be limited by the combination of climatic constraints (i.e. summer drought) and human disturbance. Evidence of a pervasive anthropogenic effect depressing treeline elevation was found in the North (Apuan Alps) Central (Gran Sasso, Velino-Sirente, Sibillini) and Southern part of Apennines (Pollino). By contrast, treeline elevation of the Laga, Simbruini, and Orsomarso mountain groups appears less affected by past anthropogenic disturbance. Finally, we recorded in the several mountain groups (i.e. Majella, Marsicani and Pollino) the coexistence of very depressed treelines just a few kilometers away from much higher treelines, among the highest ever recorded for F. sylvatica. Conclusions Finally, we argue that F. sylvatica treeline across the Apennines is locally shaped both by the interaction of low temperatures experienced by the species in its earliest life stages in snow-free open spaces with summer soil water depletion and human disturbance

a possible point of contact between cosmic ray physics and archaeology muon absorption radiography at the tharros phoenician roman site

Several on-going activities exploiting the potential of the muon-absorption radiography technique are focusing on the study of large volcanic structures located in different geographical regions. Nonetheless, the possible application of this non-destructive surveying method to other fields is also under consideration by different groups. Looking backward to the history of muon radiography, we can learn how the first important success of this technique was achieved in the archaeological field by the physicist Luis W. Alvarez in the 1960s. Further examples of possible applications can be found concerning geological and mining applications. In this paper a possible application of muon absorption radiography in the context of the archaeological research is proposed. Results of a simulation of a simplified case study are presented

a geant4 framework for generic simulations of atmospheric muon detection experiments

A flexible and adaptive simulation framework based on Geant4 is presented. The framework has been developed in order to speed up the deployment of full-featured Monte Carlo simulation codes for small/medium sized particle detection experiments with generic geometries. Specific components related to atmospheric muon experiments have been developed and are presented as well

The MURAVES muon telescope: technology and expected performances

The MURAVES project aims to study the inner structure of the upper part of the Mt. Vesuvius volcano by muon radiography (muography) technique. Very high energy muons, produced by cosmic rays in the at- mosphere, can penetrate large thickness of rocks. By measuring the at- tenuation of the muons flux trough the volcano cone is possible to obtain a 2D image of the density structure. Internal discontinuities, with a spa- tial resolution of about 10 m, can be, in principle, resolved. An absolute average density measurement can be provided too. The project, funded by the Italian Ministry of University, Research and Education (MIUR), is led by INGV and INFN. In this article the mechanical structure of the de- tectors and background suppression techniques are reported