1,721,054 research outputs found
Calibration of the Large Hodoscope ToF-Wall and Preliminary Results of the FIRST Experiment
No full textHadron therapy is an alternative way of treating cancerous tumors. It consists of irradiating tumors with protons (proton therapy) or light nuclei (alphas, carbon ions). The study of fragmentation processes is relevant for different fields of the physics concerning both basic research and applications. The energy range that is accessible at Heavy Ion Synchrotron SIS is of fundamental importance for shielding in space radiations, hadron-therapy and is interesting for different aspects exploring nuclear physics. The FIRST (Fragmentation of Ions Relevant for Space and Therapy) experiment has been designed to study nuclear fragmentation processes in the energy range between 100 and 1000 MeV/u (Mega Electron Volt per nucleon), measuring double differential cross sections, with respect to kinetic energy and scattering polar angle. This experiment was carried because there is a strong need of high-quality experimental data concerning C-12, O-16 and Fe-56 fragmentation on different targets. The first data taking has been performed at SIS accelerator facility of GSI Laboratory in Darmstadt (Germany) during August 2011 and a set of data has been collected using a 400 MeV/u carbon beam impinging on carbon and gold targets. This experiment helps not only for comparison purposes but also for the evolution of the space IC (Integrated Circuits) radiation damage evaluation. The experimental apparatus is based on both newly designed detectors placed around the target and on an already existing setup made of the ALADiN dipole magnet, the TP-MUSIC IV tracking ionization chamber, the ToF-Wall scintillator array and the LAND neutron detector. The above mentioned instruments have been integrated with new ones specifically designed for interaction region few centimeters around the target: a Start Counter (SC) based on a plastic scintillator, a drift chamber as Beam Monitor (BM), an automated mechanical system as a target holder, a silicon pixel detector Vertex to track charged fragments emerging from the target and a large-angle light fragment detector based on thick scintillators with solid photomultiplier, KENTROS (Kinetic Energy and Time Resolution Optimized on Scintillator). Most of the projectile fragments are produced in the forward direction, within small angles with respect to the beam direction and with velocities very close to those of carbon ions impinging on the target. The trajectories of these charged fragments fall within the ALADiN acceptance and, after magnetic bending, hit the ToF-Wall detector which enables measurements of the impinging point, arrival time and energy released in the scintillator array. In particular, we report performances and preliminary results obtained from ToF-Wall data analysis. This experiment will provide information about the secondary effects of nuclear fragments in healthy biological cell
Perspectives of the non-mesonic weak decay in double hypernuclei
No full textThe features of the Hyperon Induced Non Mesonic Weak Decay in double hypernuclei are shortly reviewed and a preliminary evaluation of the expected production rate in the future PANDA experiment at FAIR is reporte
Experiment FIRST: Fragmentation of 12C Beam at 400 MeV/u
No full textThe knowledge about fragmentation processes in
ion-ion interactions is fundamental in hadrontherapy and radiation protection in space missions. Hadrontherapy, based on 12C, features many advantages with respect to conventional radiation therapy with photons due to the possibility to shape the dose delivery region in tissues but side effects of the projectile fragmentation in healthy tissues are not negligible. NASA recently pointed out that measurements for some light ions and kinetic energies are missing in nuclear fragmentation databases.
FIRST experiment aims to measure the fragmentation double
differential cross section of 12 C in the energy range 100-1000 MeV/u on several elements, constituents of organic tissues and electronic devices, in order to fill some of the mentioned lack
of information on light ions.
A first set of data has been taken in 2011 at GSI (Darmstadt), using 12 C beam at 400 MeV/u on C and Au targets. About 3 · 10^7 events with C target and 5 · 10^6 with Au target were recorded.
Together with these data other sets of runs have been collected
to calibrate the forward part of the whole experimental setup, the ToF-Wall.
The calibration procedure and the detector performances, which fit the experiment requirements for what concerns efficiency, resolution and stability, will be illustrated. Moreover, some preliminary results concerning the 12 C-12 C elastic scattering, in agreement with the Rutherford model, will be presented
The antiproton interaction with an internal 12C target inside the HESR ring at FAIR
No full textIn order to fulfill the goal of producing higher rates of doubly strange hyperons, the ¯PANDA collaboration will use the antiproton ring HESR at the future facility FAIR. The low energy hyperon production by an antiproton beam requires to insert a solid target inside the ring. Unwanted side effects of such an insertion are the overwhelming amount of annihilations, which would make the detectors blind, and the fast depletion of the bunch, which circulates inside the ring. The choice of the target material impacts the hyperon production yield: Carbon turned out to provide enough initial hyperon deceleration and keep secondary interactions below a tolerable level. The use of a very thin Diamond target, together with beam steering techniques, seems to be a satisfactory solution to the above problems and will be described hereafter
Strangeness production at finite temperature and baryon density in an effective relativistic mean field model
No full textWe study the strangeness production in hot and dense nuclear medium, by requiring the conservation of the baryon density, electric charge fraction and zero net strangeness. The hadronic equation of state is investigated by means of an effective relativistic mean field model, with the inclusion of the full octet of baryons and kaon mesons. Kaons are considered taking into account of an effective chemical potential depending on the self-consistent interaction between baryons. The obtained results are compared with a minimal coupling scheme, calculated for different values of the anti-kaon optical potential and with noninteracting kaon particles. In this context, we also consider the possible onset of the kaon condensation for a wide range of temperatures and baryon densitie
Project of an internal target for the antiproton ring at FAIR
No full textThe case of the internal target for the hyper-nuclear experiment of the PANDA (antiproton Annihilation at Darmstadt) Collaboration at the High Energy Storage Ring of Facility for Antiproton and Ion Research is illustrated. After a discussion of the problems arising from the interaction of a solid internal target with an antiproton beam, the design of material, shape and sizes of a target satisfying the experimental requirements is presented. The techniques used to produce a prototype of this target are illustrated. Then the results of the tests performed on the prototype for investigating the properties (purity, radiation hardness, structure modifications after shaping) are repor- ted and the plan of the future activity is pointed ou
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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