MITO: A new directional muon telescope

Muon telescopes are instruments devoted to the observation of muons. They are produced in the atmosphere by means of the interaction of cosmic ray and solar energetic particles with atmospheric nuclei. Muons, as cosmic rays that produce them, present non uniform arrival directions and temporal variations at ground level and, along certain observation directions, could forecast the arrival of Interplanetary Coronal Mass Ejections (ICMEs) at the Earth, even earlier than neutron monitors. However, multidirectional muon telescopes are not easily affordable because of their complexity, size and cost. In this work, we present the Muon Impact Tracer and Observer (MITO) design concept. It is composed of only two stacked scintillators (1 m 2 ) with an optional lead layer that allows the filtering of unwanted particles depending on the type of application. In the case presented here, a 10 cm lead layer corresponding to the lead of a 3NM64 neutron monitor around which MITO has been built. Eight photomultipliers (PMTs) gather the light emerging from the four lateral sides of the scintillators. MITO has been conceived not only to achieve muon flux registering, but also to register muon arrival directions through the capture and analysis of multiple PMT pulse height data. The number of scintillators and electronic components is reduced, simplifying its design and construction and reducing complexity, volume, weight, power consumption and cost, and thus, achieving a reasonable performance-cost ratio in comparison to other directional telescopes based on two-layer matrices. The first prototype was shipped from Spain to Antarctica where it is now recording data. Some preliminary results are also presented.

Dosimetric evaluation of a novel electron–photon mixed beam, produced by a medical linear accelerator

AimThis study deals with the characteristics of simultaneous photon and electron beams in homogenous and inhomogeneous phantoms by experimental and Monte Carlo dosimetry, for therapeutic purposes. Materials and methods: Both 16 and 20 MeV high-energy electron beams were used as the original beam to strike perforated lead sheets to produce the mixed beam. The dosimetry results were achieved by measurement in an ion chamber in a water phantom and film dosimetry in a Perspex nasal phantom, and then compared with those calculated through a simulation approach. To evaluate two-dimensional dose distribution in the inhomogeneous medium, the dose–area histogram was obtained.ResultsThe highest percentage of photon contribution in mixed beam was found to be 36% for 2-mm thickness of lead layer with holes diameter of 0·2 cm for a 20 MeV primary electron energy. For small fields, the percentage depth dose parameters variations were found to be similar to pure electron beam within ±2%. The most feasible flatness in beam profile was 11% for pure electron and 7% for the mixed beam. Penumbra changes as function of depth was about ten times better than in pure electron field.ConclusionsThe results present some dosimetric advantages that can make this study a platform for the production of simultaneous mixed beams in future linear accelerators (LINACs), which through redesign of the LINAC head, which could lead to setup error reduction and a decrease of intra-fractional tumour cells repair.

Towards Fabrication of Low-Cost Carbon/Ceramics Membranes: Substrate Modification

This paper presents a novel method for fabrication of carbon membranes for gas separation by mean of surface modification with a conventional 2B pencil on the low-cost macroporous Al2O3 substrate. The resulting membrane was characterized by SEM, which shows that the modified membrane is continuous and uniform without defects. Gas permeation experiments were conducted by single gas measurements (test gas: H2, CO2, O2 and N2) at 20–80 °C under 100–400 kPa. The results show that the pencil lead layer can effectively prevent deep infiltration of precursor solution into the pores of substrate, and that gas transport through carbon membrane follows the molecular sieving mechanism. Based on the modified substrate, the carbon membrane exhibits good permeability (up to the order magnitude of 10-9 mol/m2 s Pa) and separation capability such as H2/N2 of 37.3, CO2/N2 of 11.2, and O2/N2 of 8.3.

Study into laser short-pulse heating of a layered structure

Laser short-pulse heating of a lead—silicon—gold-layered structure is considered and non-equilibrium equation in the lattice and electron subsystems is formulated using the electron kinetic theory approach. The Seebeck coefficient in the metallic and silicon layers is also formulated. Electron and lattice site temperature rise in the subsystems and the Seebeck coefficients are computed for time exponentially decaying pulse. The study is extended to include the influence of the first layer (lead layer) thickness on temperature rise and the Seebeck coefficients. It is found that the lattice site temperature across the interface of the lead and silicon layers increases sharply. The Seebeck coefficient predicted in the silicon layer is higher than in the metallic layers in the structure.

A Comparative Examination of the Friction Coefficient of two Different Sliding Bearing

The aim of this research work is to investigate the sliding properties of the monotectic surface layers developed by a laser surface-treatment technology. The coatings-remelting technology has been chosen from the laser surface treatment methods. The surface of Al-Si alloy was coated with a lead layer by galvanizing, then the basic material and the surface layer were remelted together by using laser beam produced a monotectic Al- Pb surface layer. The structure of monotectic surface layer has been determined by means of a light microscope and scanning electron microscope. The sliding properties of the basic material (as cast, nearly eutectic Al-Si alloy), the Al-Si-Pb monotectic surface layer as well as the Al-Cu-Sn sliding bearing (Al-Cu matrix and Sn sliding layer) used in the gas industry have been investigated.

Effectiveness of syringe shieldings using radionuclides in radiation synovectomy

Summary Aim: The radiation exposure in radiation synovectomy was investigated for technician and therapist using Erbium-169, Rhenium-186 and Yttrium-90 with and without syringe shieldings. Methods: Dose rates were measured in relation to the distance of the syringe containing the radionuclide. Measurements were repeated using syringe shieldings which consist of plastic surrounded by a lead layer. Results: The most relevant radiation exposure arises from Yttrium-90. Using syringe shieldings radiation exposure can be reduced by a factor of thousand. Conclusion: This kind of radiological protection is completely sufficient for the therapist. Concerning the technician preparing the radiopharmaceutics, the limit of the official German dosimetry service (500 mSv) might be exceeded if no special radiological protection is established. Thus, special dosimetry is recommended.