Particle identification with the AMS-02 RICH detector: search for dark matter with antideuterons

The Alpha Magnetic Spectrometer (AMS), whose final version AMS-02 is to be installed on the International Space Station (ISS) for at least 3 years, is a detector designed to measure charged cosmic ray spectra with energies up to the TeV region and with high energy photon detection capability up to a few hundred GeV, using state-of-the art particle identification techniques. It is equipped with several subsystems, one of which is a proximity focusing Ring Imaging Cherenkov (RICH) detector 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 (Delta beta / beta ~ 10^-3 and 10^-4 for Z=1 and Z=10-20, respectively) at kinetic energies of a few GeV/nucleon. Combining velocity measurements with data on particle rigidity from the AMS-02 Tracker (Delta R / R ~ 2% for R=1-10 GV) it is possible to obtain a reliable measurement for particle mass. One of the main topics of the AMS-02 physics program is the search for indirect signatures of dark matter. Experimental data indicate that dark, non-baryonic matter of unknown composition is much more abundant than baryonic matter, accounting for a large fraction of the energy content of the Universe. Apart from antideuterons produced in cosmic-ray propagation, the annihilation of dark matter will produce additional antideuteron fluxes. Detailed Monte Carlo simulations of AMS-02 have been used to evaluate the detector's performance for mass separation, a key issue for anti-D/anti-p separation. Results of these studies are presented.Comment: 5 pages. Contribution to the 20th European Cosmic Ray Symposium (Lisbon 2006). Presenter: Rui Pereir

Particle identification with the AMS-02 RICH detector: D/p and anti-D/anti-p separation

The Alpha Magnetic Spectrometer (AMS), whose final version AMS-02 is to be installed on the International Space Station (ISS) for at least 3 years, is a detector designed to measure charged cosmic ray spectra with energies up to the TeV region and with high energy photon detection capability up to a few hundred GeV, using state-of-the art particle identification techniques. Among several detector subsystems, AMS includes a proximity focusing RICH enabling precise measurements of particle electric charge and velocity. The combination of both these measurements together with the particle rigidity measured on the silicon tracker endows a reliable measurement of the particle mass. The main topics of the AMS-02 physics program include detailed measurements of the nuclear component of the cosmic-ray spectrum and the search for indirect signatures of dark matter. Mass separation of singly charged particles, and in particular the separation of deuterons and antideuterons from massive backgrounds of protons and antiprotons respectively, is essential in this context. Detailed Monte Carlo simulations of AMS-02 have been used to evaluate the detector's performance for mass separation at different energies. The obtained results and physics prospects are presented.Comment: 5 pages. Contribution to the Sixth International Workshop on New Worlds in Astroparticle Physics (Faro 2007). Presenter: Rui Pereir

Cosmic ray velocity and electric charge measurements with the AMS/RICH detector: prototype results

The Alpha Magnetic Spectrometer (AMS) to be installed on the International Space Station (ISS) will measure charged cosmic ray spectra of elements up to iron, in the rigidity range from 1 GV to 1 TV, for at least three years. AMS is a large angular spectrometer composed of different subdetectors, including a proximity focusing Ring Imaging CHerenkov (RICH) detector. This will be equipped with a mixed radiator made of aerogel and sodium fluoride (NaF), a lateral conical mirror and a detection plane made of 680 photomultipliers coupled to light guides. The RICH detector allows measurements of particle's electric charge up to iron, and particle's velocity. Two possible methods for reconstructing the Cherenkov angle and the electric charge with the RICH will be discussed. A RICH prototype consisting of a detection matrix with 96 photomultipliers, a segment of a conical mirror and samples of the radiator materials was built and its performance was evaluated using ion beam data. Results from the last test beam performed with ion fragments resulting from the collision of a 158 GeV/c/nucleon primary beam of indium ions (CERN SPS) on a lead target are reported. The large amount of collected data allowed to test and characterize different aerogel samples and the NaF radiator. In addition, the reflectivity of the mirror was evaluated. The data analysis confirms the design goals.Comment: 5 pages. Contribution to the 20th European Cosmic Ray Symposium in Lisbon, Portugal. September 5th-8th 2006. Presenter: Luisa Arrud

The Ring Imaging Cherenkov detector of the AMS experiment: test beam results with a prototype

The Alpha Magnetic Spectrometer (AMS) to be installed on the International Space Station (ISS) will be equipped with a proximity Ring Imaging Cherenkov (RICH) detector for measuring the velocity and electric charge of the charged cosmic particles. This detector will contribute to the high level of redundancy required for AMS as well as to the rejection of albedo particles. Charge separation up to iron and a velocity resolution of the order of 0.1% for singly charged particles are expected. A RICH protoptype consisting of a detection matrix with 96 photomultiplier units, a segment of a conical mirror and samples of the radiator materials was built and its performance was evaluated. Results from the last test beam performed with ion fragments resulting from the collision of a 158 GeV/c/nucleon primary beam of indium ions (CERN SPS) on a lead target are reported. The large amount of collected data allowed to test and characterize different aerogel samples and the sodium fluoride radiator. In addition, the reflectivity of the mirror was evaluated. The data analysis confirms the design goals.Comment: 4 pages, 5 figures. Contribution to the 10th Topical Seminar on Innovative Particle and Radiation Detectors (Siena, Italy 2006

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.Comment: 5 pages. Contribution to the Fifth International Workshop on New Worlds in Astroparticle Physics (Faro 2005). Presenter: Rui Pereir

Museu Virtual da FBAUL

Conferência apresentada no âmbito do Projecto Conversas à Volta da Mesa, organizado pela Biblioteca da FBAU

Preparação de nanotubos de dióxido de titânio funcionalizados com nitrogênio para degradação do corante alaranjado de metila

TCC (graduação) - Universidade Federal de Santa Catarina. Centro de Ciências Físicas e Matemáticas. Curso de Química.Neste trabalho foram sintetizados nanotubos de dióxido de titânio pelo método hidrotermal, vantajoso por seu baixo custo reacional, alta reprodutibilidade e facilidade em produzir esse material de alta cristalinidade. Os nanotubos foram funcionalizados, pela inserção de átomos de nitrogênio em sua superfície, a partir do reagente hidróxido de amônio. O material sintetizado foi caracterizado por técnicas físico-químicas como difração de raios X, espectroscopia de infravermelho, adsorção/dessorção de nitrogênio e microscopia eletrônica de transmissão. A eficiência do dióxido de titânio como catalisador foi avaliada através da fotodegradação do corante alaranjado de metila. Por conta da pandemia do coronavírus, a conclusão de alguns testes mostrou-se inviável. Entretanto, os nanotubos de dióxido de titânio funcionalizados, embora não tenham sido testados na degradação do corante, foram sintetizados e caracterizados, estando prontos para serem aplicados como possíveis materiais catalíticos