Mario Pimenta

A model for Mars radiation environment characterization

A modeling framework for the prediction of the Martian radiation environment is presented. Features include input solar cycle modulated cosmic ray and solar particle event spectra, based both on CREME-96, the transport of this radiation in the Martian atmosphere and regolith, including creation of secondaries, using the Geant4 Monte Carlo toolkit. Details of the atmosphere are derived from the European Mars Climate Database with a dense topological grid and layering of the atmosphere. Seasonal and diurnal variations are considered. Surface topology is derived from the Mars Orbiter Laser Altimeter (MOLA) and geology is modeled. The outputs are full particle transport histories, maps of radiation fluxes, and doses. The model will be applied to future European Mars missions.

A model for the transport of muons in extensive air showers

Abstract In this article we identify the key elements that govern the propagation of muons from the production in extensive air showers to ground. We describe a model based on simple assumptions that propagates the muons starting from the few relevant distributions at production. We compare the results to the ground distributions given by a full air shower Monte Carlo. This study is motivated by the need of modeling the muon component in extensive air showers with the goal of experimentally reconstructing their distributions at production, which act as a footprint of the hadronic cascade.

ISOTOPE SEPARATION WITH THE RICH DETECTOR OF THE AMS EXPERIMENT

The Alpha Magnetic Spectrometer (AMS), to be installed on the International Space Station (ISS) in 2008, is a cosmic ray detector with several subsystems, one of which is a proximity focusing Ring Imaging Cherenkov (RICH) detector. This detector will be equipped with a dual radiator (aerogel+NaF), a lateral conical mirror and a detection plane made of 680 photomultipliers and light guides, enabling precise measurements of particle electric charge and velocity. Combining velocity measurements with data on particle rigidity from the AMS Tracker it is possible to obtain a measurement for particle mass, allowing the separation of isotopes. A Monte Carlo simulation of the RICH detector, based on realistic properties measured at ion beam tests, was performed to evaluate isotope separation capabilities. Results for three elements -- H (Z=1), He (Z=2) and Be (Z=4) -- are presented.

Interpretation of measurements of the number of muons in extensive air shower experiments

Abstract In this paper we analyze the energy evolution of the muon content of air showers between 1018.4 and 1019.6 eV to be able to determine the most likely mass composition scenario from future number of muons measurements. The energy and primary mass evolution of the number of muons is studied based on the Heitler–Matthews model and Monte Carlo simulation of the air shower. A simple model to describe the evolution of the first and second moments of number of muons distributions is proposed and validated. An analysis approach based on the comparison between this model’s predictions and data to discriminate among a set of composition scenarios is presented and tested with simulations. It is shown that the composition scenarios can be potentially discriminated under the conditions imposed by the method. The discrimination power of the proposed analysis is stable under systematic changes of the absolute number of muons from model predictions and on the scale of the reconstructed energy.

Applications of GEANT4 in astroparticle experiments

The GEANT4 Monte Carlo radiation transport toolkit, developed by the RD44 and GEANT4 Collaborations, aims to become a tool of generalized application in high energy physics, nuclear physics, astrophysics, and medical physics research. Due to its object-oriented design, GEANT4 is a distinct new approach for the development of flexible simulation applications. A wide energy range coverage for both electromagnetic and hadronic physics processes is offered. GEANT4 provides also an optical physics process category, allowing the production and propagation of scintillation and Cherenkov emitted light to be described. Such capabilities are well tailored for the requirements of the new generation of astrophysics experiments to be installed on the International Space Station, like EUSO and AMS. In this paper, the system architecture of a GEANT4 based simulation framework and its application to EUSO/ULTRA and AMS/RICH performance studies are presented.

Autonomous RPCs for a Cosmic Ray ground array

We report on the behaviour of Resistive Plate Chambers (RPC) developed for muon detection in ultra-high energy cosmic ray (UHECR) experiments. The RPCs were developed for the MARTA project and were tested on field conditions. These RPCs cover an area of

Simulation of Single Event Effects and Rate Prediction: CODES an ESA Tool

1.5 times 1.2,{m^2}

A Geant4 Based Engineering Tool for Fresnel Lenses

and are instrumented with 64 pickup electrodes providing a segmentation better than

MARTA: a high-energy cosmic-ray detector concept for high-accuracy muon measurement

20,

FAMOUS: a prototype silicon-photomultiplier telescope for the fluorescence detection of ultra-high-energy cosmic rays

cm. By shielding the detector units with enough slant mass to absorb the electromagnetic component in the air showers, a clean measurement of the muon content is allowed, a concept to be implemented in a next generation of UHECR experiments. The operation of a ground array detector poses challenging demands, as the RPC must operate remotely under extreme environmental conditions, with limited budgets for power and minimal maintenance. The RPC, DAQ, High Voltage and monitoring systems are enclosed in an aluminium-sealed case, providing a compact and robust unit suited for outdoor environments, which can be easily deployed and connected. The RPCs developed at LIP-Coimbra are able to operate using a very low gas flux, which allows running them for few years with a small gas reservoir. Several prototypes have already been built and tested both in the laboratory and outdoors. We report on the most recent tests done in the field that show that the developed RPCs have operated in a stable way for more than 2 years in field conditions.