The AMS-02 Time of Flight System. Final Design

The AMS-02 detector is a superconducting magnetic spectrometer that will operate on the International Space Station. The time of flight (TOF) system of AMS-02 is composed by four scintillator planes with 8, 8, 10, 8 counters each, read at both ends by a total of 144 phototubes. This paper describes the new design, the expected performances, and shows preliminary results of the ion beam test carried on at CERN on October 2002.Comment: 4 pages, 6 EPS figures. Proc. of the 28th ICRC (2003

¿Es la Argentina el país donde se cumple el trilema monetario?

Abstract The monetary trilemma states that it is impossible for a monetary authority to simultaneously have a fixed foreign exchange rate within a context of capital mobility and an independent monetary policy which targets internal objectives. The purpose of this paper is to validate said theory through a model which considers the capital and financial account as a function of the of currency exchange rate, the domestic and international interest rate and the inflation rate. The results show that even if the three objectives are desirable, it is impossible to to meet them simultaneously, in addittion to stating how the Central Bank can overcome this trilemma

The AMS-02 RICH Imager Prototype - In-Beam Tests with 20 GeV/c per Nucleon Ions -

A prototype of the AMS Cherenkov imager (RICH) has been tested at CERN by means of a low intensity 20 GeV/c per nucleon ion beam obtained by fragmentation of a primary beam of Pb ions. Data have been collected with a single beam setting, over the range of nuclear charges 2<Z<~45 in various beam conditions and using different radiators. The charge Z and velocity beta resolutions have been measured.Comment: 4 pages, contribution to the ICRC 200

Lower-limb amputees can reduce the energy cost of walking when assisted by an Active Pelvis Orthosis

Exoskeletons could compete with active prostheses as effective aids to reduce the increased metabolic demands faced by lower-limb amputees during locomotion. However, little evidence of their efficacy with amputees has been provided so far. In this paper, a portable hip exoskeleton has been tested with seven healthy subjects and two transfemoral amputees, with the final goal to verify whether a hip flexion-extension assistance could be effective in reducing the metabolic cost of walking. The metabolic power of the participants was estimated through indirect calorimetry during alternated repetitions of three treadmill-based walking conditions: without the exoskeleton (NoExo), with the exoskeleton in zero-torque mode (ExoTM) and with the exoskeleton providing hip flexion-extension assistance (ExoAM). The results showed that the exoskeleton reduced the net metabolic power of the two amputees in ExoAM with respect to NoExo, by 5.0% and 3.4%. With healthy subjects, a 5.5±3.1% average reduction in the metabolic power was observed during ExoAM compared to ExoTM (differences were not statistically significant), whereas ExoAM required 3.9±3.0% higher metabolic power than NoExo (differences were not statistically significant). These results provide initial evidence of the potential of exoskeletal technologies for assisting lower-limb amputees, thereby paving the way for further experimentations

Experiences with workflows for automating data-intensive bioinformatics

High-throughput technologies, such as next-generation sequencing, have turned molecular biology into a data-intensive discipline, requiring bioinformaticians to use high-performance computing resources and carry out data management and analysis tasks on large scale. Workflow systems can be useful to simplify construction of analysis pipelines that automate tasks, support reproducibility and provide measures for fault-tolerance. However, workflow systems can incur significant development and administration overhead so bioinformatics pipelines are often still built without them. We present the experiences with workflows and workflow systems within the bioinformatics community participating in a series of hackathons and workshops of the EU COST action SeqAhead. The organizations are working on similar problems, but we have addressed them with different strategies and solutions. This fragmentation of efforts is inefficient and leads to redundant and incompatible solutions. Based on our experiences we define a set of recommendations for future systems to enable efficient yet simple bioinformatics workflow construction and execution.Pubblicat

The Ring Imaging Cherenkov detector (RICH) of the AMS experiment

The Alpha Magnetic Spectrometer (AMS) experiment to be installed on the International Space Station (ISS) will be equipped with a proximity focusing Ring Imaging Cherenkov (RICH) detector for measuring the electric charge and velocity of the charged cosmic particles. A RICH prototype consisting of 96 photomultiplier units, including a piece of the conical reflector, was built and its performance evaluated with ion beam data. Preliminary results of the in-beam tests performed with ion fragments resulting from collisions of a 158 GeV/c/nuc primary beam of Indium ions (CERN SPS) on a Pb target are reported. The collected data included tests to the final front-end electronics and to different aerogel radiators. Cherenkov rings for a large range of charged nuclei and with reflected photons were observed. The data analysis confirms the design goals. Charge separation up to Fe and velocity resolution of the order of 0.1% for singly charged particles are obtained.Comment: 29th International Conference on Cosmic Rays (Pune, India

Isotopic Composition of Light Nuclei in Cosmic Rays: Results from AMS-01

The variety of isotopes in cosmic rays allows us to study different aspects of the processes that cosmic rays undergo between the time they are produced and the time of their arrival in the heliosphere. In this paper we present measurements of the isotopic ratios 2H/4He, 3He/4He, 6Li/7Li, 7Be/(9Be+10Be) and 10B/11B in the range 0.2-1.4 GeV of kinetic energy per nucleon. The measurements are based on the data collected by the Alpha Magnetic Spectrometer, AMS-01, during the STS-91 flight in 1998 June.Comment: To appear in ApJ. 12 pages, 11 figures, 6 table

In-beam tests of the AMS RICH prototype with 20 A GeV/c secondary ions

Abstract A prototype of the AMS Cherenkov imager (RICH) has been tested by means of a low intensity 20 GeV /c per nucleon ion beam coming from the fragmentation of a primary beam of Pb ions. Data have been collected for charges