Suchergebnisse

Neutron radiation fields are generated in various scientific research areas and applications, for example in radiation therapy, in radionuclide production for medical applications, in material science studies, for design of electronic components in energy production, military activities, and in neutron radiography. Moreover, high energy neutrons are the dominant component of the prompt radiation field present outside the shielding of high-energy accelerators and are a significant component of the cosmic radiation fields interacting with aircrafts and in spacecrafts. The Space Agencies programs are focusing on human space exploration. The return to the moon and the construction of a permanent base (Moon Village) and the Mars exploration are now among the highest priorities both for NASA and ESA. However, the health risks caused by exposure to cosmic radiation are acknowledged as one of the major showstopper for safe colonization of the Solar systems. Shielding is the only practical countermeasure available, but there is still a lack of information regarding the neutrons stopping performances of the new materials currently under evaluation in the context of long term space missions (e.g. highly hydrogenated materials, in situ resource utilizations and active shields). The recently founded SPARE project aims to carry out a shielding test campaign of active and passive materials using high energy protons and neutrons at the accelerator facilities in Trento (TIFPA) and Legnaro (SPES- Laboratori Nazionali di Legnaro LNL). For this reason the development of a new Quasi Monoenergetic Neutron (QMN) sources capable of accelerating neutrons with energies up to 70MeV in LNL will be a major goal of the project since no other QMN facility is currently in operation in Europe. An innovative detector (MONDO) developed by the "Museo Storico della Fisica e Centro Studi e Ricerca E.Fermi", able to track both neutrons and charged particles, will be used to measure the radiation transmitted and emitted by the shielding. The aim of this thesis is to present the MONDO neutron tracker and to describe its application within the SPARE project with a particular focus on its application as Neutron Beam Monitor for the new NEPIR QMN facility planned at LNL. Chapter 1 is dedicated to the description of the basic principles of neutron physics and dosimetry with a focus on the possible applications in space and Particle Therapy. An overview about the existing Quasi Mono-energetic Neutron facilities is also presented. The chapter conclusion contains an overview of the SPARE project. Chapter 2 is dedicated to the MONDO detector: the detection techniques and the tracker development status are described. The characterisation measurements already performed on a small MONDO prototype are also presented. In Chapter 3 a detailed description of the MONDO readout system, the SBAM sensor, is presented. Chapter 4 is dedicated to the presentation of the detector performances evaluated by means of a full-Montecarlo simulation in FLUKA. In the last Chapter (5) measurements on the first sensor chip with different source are illustrated.