718 research outputs found

    A Tracking Fiber Detector based on Silicon Photomultipliers for the Kaos Spectrometer

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    A tracking detector based on two meters long scintillating fibers read out by silicon photomultipliers (SiPM) is being developed for the Kaos spectrometer at the Mainz Microtron MAMI. Results from a prototype setup using 2 mm square fibers and large area SiPM readout are presented. The detection efficiency of such a combination was measured to be between 83 and 100% depending on the threshold on the SiPM amplitude. A Monte Carlo simulation based on a physical model was employed in order to extract the photon detection efficiency of the SiPM devices.Comment: Contributed to 2008 IEEE Nuclear Science Symposium, 19-25 October 2008, Dresden, German

    Improvements to model of projectile fragmentation

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    In a recent paper [Phys. Rev. C 044612 (2011)] we proposed a model for calculating cross-sections of various reaction products which arise from disintegration of projectile like fragment resulting from heavy ion collisions at intermediate or higher energy. The model has three parts: (1) abrasion, (2) disintegration of the hot abraded projectile like fragment (PLF) into nucleons and primary composites using a model of equilibrium statistical mechanics and (3) possible evaporation of hot primary composites. It was assumed that the PLF resulting from abrasion has one temperature T. Data suggested that while just one value of T seemed adequate for most cross-sections calculations, it failed when dealing with very peripheral collisions. We have now introduced a variable T=T(b) where b is the impact parameter of the collision. We argue there are data which not only show that T must be a function of b but, in addition, also point to an approximate value of T for a given b. We propose a very simple formula: T(b)=D_0+D_1(A_s(b)/A_0) where A_s(b) is the mass of the abraded PLF and A_0 is the mass of the projectile; D_0 and D_1 are constants. Using this model we compute cross-sections for several collisions and compare with data.Comment: 27 pages, 16 figure

    Production of hypernuclei in multifragmentation of nuclear spectator matter

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    In peripheral collisions of relativistic heavy ions highly excited spectators containing Lambda-hyperons can be produced. Such strange spectator matter may undergo a break-up into many fragments (multifragmentation) as it is well established for ordinary nuclear systems. We generalize the statistical multifragmentation model, previously successfully used for the description of experimental data, for the case of hypernuclear systems. We predict relative yields of hypernuclei and the main characteristics of such a break-up. We point at a connection of this phenomenon with a liquid-gas phase transition in hypermatter.Comment: 4 pages including 4 figure

    The nuclear liquid-gas phase transition within Fermionic Molecular Dynamics

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    The time evolution of excited nuclei, which are in equilibrium with the surrounding vapour, is investigated. It is shown that the finite nuclear systems undergo a first oder phase transition. The caloric curve is presented for excited Oxygen, Magnesium, Aluminum and Calcium and the critical temperature is estimated for Oxygen.Comment: 8 pages, 3 postscript figures, uses 'epsfig.sty'. Submitted to Phys. Lett. B. More information available at http://www.gsi.de/~schnack/fmd.htm

    Detector developments for the hypernuclear programme at PANDA

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    The technical design of the PANDA experiment at the future FAIR facility next to GSI is progressing. At the proposed anti-proton storage ring the spectroscopy of double Lambda hypernuclei is one of the four main topics which will be addressed by the Collaboration. The hypernuclear experiments require (i) a dedicated internal target, (ii) an active secondary target of alternating silicon and absorber material layers, (iii) high purity germanium (HPGe) detectors, and (iv) a good particle identification system for low momentum kaons. All systems need to operate in the presence of a high magnetic field and a large hadronic background. The status of the detector developments for this programme is summarized.Comment: Contributed to 2008 IEEE Nuclear Science Symposium, 19-25 October 2008, Dresden, German
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