A Study of the Radiation Tolerance of CVD Diamond to 70 MeV Protons, Fast Neutrons and 200 MeV Pions.

We measured the radiation tolerance of commercially available diamonds grown by the Chemical Vapor Deposition process by measuring the charge created by a 120 GeV hadron beam in a 50 µm pitch strip detector fabricated on each diamond sample before and after irradiation. We irradiated one group of samples with 70 MeV protons, a second group of samples with fast reactor neutrons (defined as energy greater than 0.1 MeV), and a third group of samples with 200 MeV pions, in steps, to (8.8±0.9) × 1015 protons/cm2, (1.43±0.14) × 1016 neutrons/cm2, and (6.5±1.4) × 1014 pions/cm2, respectively. By observing the charge induced due to the separation of electron-hole pairs created by the passage of the hadron beam through each sample, on an event-by-event basis, as a function of irradiation fluence, we conclude all datasets can be described by a first-order damage equation and independently calculate the damage constant for 70 MeV protons, fast reactor neutrons, and 200 MeV pions. We find the damage constant for diamond irradiated with 70 MeV protons to be 1.62±0.07(stat)±0.16(syst)× 10-18 cm2/(p µm), the damage constant for diamond irradiated with fast reactor neutrons to be 2.65±0.13(stat)±0.18(syst)× 10-18 cm2/(n µm), and the damage constant for diamond irradiated with 200 MeV pions to be 2.0±0.2(stat)±0.5(syst)× 10-18 cm2/(π µm). The damage constants from this measurement were analyzed together with our previously published 24 GeV proton irradiation and 800 MeV proton irradiation damage constant data to derive the first comprehensive set of relative damage constants for Chemical Vapor Deposition diamond. We find 70 MeV protons are 2.60 ± 0.29 times more damaging than 24 GeV protons, fast reactor neutrons are 4.3 ± 0.4 times more damaging than 24 GeV protons, and 200 MeV pions are 3.2 ± 0.8 more damaging than 24 GeV protons. We also observe the measured data can be described by a universal damage curve for all proton, neutron, and pion irradiations we performed of Chemical Vapor Deposition diamond. Finally, we confirm the spatial uniformity of the collected charge increases with fluence for polycrystalline Chemical Vapor Deposition diamond, and this effect can also be described by a universal curve.

Volcanoes in Italy and the role of muon radiography.

Cosmic-ray muon radiography (muography), an imaging technique that can provide measurements of rock densities within the top few 100 m of a volcanic cone, has now achieved a spatial resolution of the order of 10 m in optimal detection conditions. Muography provides images of the top region of a volcano edifice with a resolution that is considerably better than that typically achieved with other conventional methods (i.e. gravimetric). We expect such precise measurements, to provide us with information on anomalies in the rock density distribution, which can be affected by dense lava conduits, low-density magma supply paths or the compression with the depth of the overlying soil. The MUon RAdiography of VESuvius (MURAVES) project is now in its final phase of construction and deployment. Up to four muon hodoscopes, each with a surface of roughly 1 m2, will be installed on the slope of Vesuvius and take data for at least 12 months. We will use the muographic profiles, combined with data from gravimetric and seismic measurement campaigns, to determine the stratigraphy of the lava plug at the bottom of the Vesuvius crater, in order to infer potential eruption pathways. While the MURAVES project unfolds, others are using emulsion detectors on Stromboli to study the lava conduits at the top of the volcano. These measurements are ongoing: they have completed two measurement campaigns and are now performing the first data analysis.This article is part of the Theo Murphy meeting issue 'Cosmic-ray muography'.

Laser scanner and UAV digital photogrammetry as support tools for cosmic-ray muon radiography applications: an archaeological case study from Italy.

The use of light detection and ranging technologies, i.e. terrestrial laser scanner (TLS), airborne laser scanner (ALS) and mobile laser scanner (MLS), together with the unmanned aerial vehicles digital photogrammetry (UAV-DP) and satellite data are proving to be fundamental tools to carry out reliable muographic measurement campaigns. The main purpose of this paper is to propose a workflow to correctly plan and exploit these types of data for muon radiography aims. To this end, a real case study is presented: searching for hidden tombs in the Etruscan necropolis of Palazzone (Umbria, Italy). A high-resolution digital elevation model (DEM) and three-dimensional models of the ground surface/sub-surface of the study area were created by merging data obtained using different survey methods to achieve the most accurate three-dimensional environment. Indeed, the simulated muon flux transmission used to infer relative transmission values, and the estimated density distribution, depends on the reliability of the three-dimensional reconstructed ground surface model. The aim of this study is to provide knowledge on the use of TLS and UAV-DP data and GPS-acquired points within the transmission-based muography process and how these data could improve or worsen the muon imaging results. Moreover, this study confirmed that muography applications require a multidisciplinary approach.

Three-dimensional muon imaging of cavities inside the Temperino mine (Italy).

Muon radiography (muography) is an imaging technique based on atmospheric muon absorption in matter that allows to obtain two and three-dimensional images of internal details of hidden objects or structures. The technique relies on atmospheric muon flux measurements performed around and underneath the object under examination. It is a non-invasive and passive technique and thus can be thought of as a valid alternative to common prospecting techniques used in archaeological, geological and civil security fields. This paper describes muon radiography measurements, in the context of archaeological and geological studies carried out at the Temperino mine (LI, Tuscany, Italy), for the search and three-dimensional visualisation of cavities. This mine has been exploited since Etruscan times until recently (1973), and is now an active tourist attraction with public access to the tunnels. Apart from the archaeological interest, the importance of mapping the cavities within this mine lies in identifying the areas where the extraction ores were found and also in the safety issues arising from the tourist presence inside the mine. The three-dimensional imaging is achieved with two different algorithms: one involving a triangulation of two or more measurements at different locations; the other, an innovative technique used here for the first time, is based on the back-projections of reconstructed muon tracks. The latter requires only a single muographic data tacking and is to be preferred in applications where more than one site location can be difficult to access. Finally the quality of the three-dimensional muographic imaging was evaluated by comparing the results with the laser scan profiles obtained for some known cavities within the Temperino mine.

3D Muography for the Search of Hidden Cavities.

Muography (or muon radiography) is a technique that exploits the penetration capability of muons, elementary particles similar to electrons but with a mass about 200 times larger. High energy muons are naturally produced in the interactions of cosmic rays with the Earth atmosphere. The measurement of their absorption in matter allows the imaging of the inner structure of large bodies. The technological developments in the detection of elementary particles have opened the way to its application in various fields, such as archaeology, studies of geological structures, civil engineering and security issues. We have developed a new approach to the three-dimensional muography of underground structures, capable of directly localising hidden cavities and of reconstructing their shape in space. Our measurements at Mt. Echia, the site of the earliest settlement of the city of Naples in the 8th century BC, have led us to the discovery of a hidden underground cavity, whose existence was not evident with the usual two-dimensional muography graphs. We demonstrate here that our original approach definitely enhances muography discovery potential, especially in case of complex underground systems.

Author Correction: 3D Muography for the Search of Hidden Cavities.

A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has not been fixed in the paper.