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Now showing items 1 - 13 of 13

  • The influence of Ceres on the dynamical evolution of the Zdenekhorsky/Nemesis asteroid family

    Carruba, V.   Barletta, W.  

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  • Remembrances of John Madey and Rodolfo Bonifacio

    Barletta, W.   Parmigiani, F.  

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  • Editorial

    Barletta, W.   Karlsson, E.   Klanner, R.   Knoll, G.F.  

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  • Collisions

    Barletta, W.   Johnson, M.   Ludlam, T.   Slaughter, A. J.   Taft, H. D.  

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  • [AIP The sixth advanced accelerator concepts workshop - Fontana, Wisconsin (USA) (12?18 Jun 1994)] AIP Conference Proceedings - Plasma lens experiments at the final focus test beam

    Barletta, W.   Chattopadhyay, S.   Chen, P.   Cline, D.   Craddock, W.   Gabella, W.   Hsu, I.   Iverson, R.   Katsouleas, T.   Kwok, P.   Lai, P.   Leemans, W.   Liou, R.   Meyerhofer, D. D.   Nakajima, K.   Nakanishi, H.   Ng, C. K.   Nishida, Y.   Norem, J.   Ogata, A.   Rajagopalan, S.   Shintake, T.   Rosenzweig, J.   Ross, M.   Sessler, A.   Spencer, J.   Su, J. J.   Walker, N.   Westenskow, G.   Whittum, D.   Williams, R.   Wurtele, J.  

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  • [IEEE International Conference on Particle Accelerators - Washington, DC, USA (17-20 May 1993)] Proceedings of International Conference on Particle Accelerators - PEP-II design update and R&D results

    Barletta, W.   Zisman, M.S.   Bell, R.A.   Dorfan, J.M.  

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  • Engineering Study of the Sector Magnet for the Dae delta alus Experiment

    Radovinsky, A.   Smith, B.   Miller, C. E.   Minervini, J. V.   Cheadle, M.   Calabretta, L.   Alonso, J.   Conrad, J.   Calanna, A.   Barletta, W.  

    The Dae delta alus experiment seeks to evaluate neutrino scattering effects that go beyond the standard model. Modular accelerators are employed to produce 800 MeV proton beams at the megawatt power level directed toward a target, producing neutrinos. The Superconducting Ring Cyclotron consists of identical sectors (currently 6) of superconducting dipole magnets with iron return frames. The Dae delta alus Collaboration has produced a conceptual design for the magnet, which, after several iterations, is the current hest design that achieves the physics requirements of the experiment. The main purpose of the analytical effort, results of which are presented here, is to develop a viable engineering design satisfying requirements to the superconductor, as well as structural and cryogenic requirements. The work includes proposed conceptual approaches, solid modeling and analyses for the conductor and winding pack design, high-temperature superconductor and copper current leads for the magnet, structural design of the magnet cold mass, cryostat and warm-to-cold supports, cryogenic design of the magnet cooling system, and magnet power supply sizing A description of the winding pack design, structural analysis, and cryogenic system is reported.
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  • The influence of Ceres on the dynamical evolution of the Zdenekhorsky/ Nemesis asteroid family

    Carruba, V   Barletta, W.  

    The Nemesis family, also identified as the Zdenekhorsky family by some authors, is an "incomplete" asteroid family in the central main belt, characterized by an asymmetric distribution between its left and right side, with most of its members located in the left part of the family. It has been suggested that this asymmetry, as well as the shape of its left slope, could have been significantly affected by Ceres, either though close encounters or because of the effect of the nodal linear resonance nu(1C). Several age estimates were also found for this family, ranging from a minimum of 150 +/- 80 Myr to a maximum of 440 +/- 20 Myr. Here we study the effect that Ceres may have had on the dynamical evolution of this family. For this purpose, we performed several numerical simulations that include the Yarkovsky effect and either consider or neglect Ceres as a massive body. We found that the asymmetric shape of this family does not seem to be a product of the local dynamics, but may be an intrinsic feature of the original ejection velocity field by which this family was created. If we assume that the current population of asteroids in librating states of the nu(1C) secular resonance is currently in a steady-state and originates from the Nemesis family, this population will no longer be sustainable on timescales of 200 Myr since the group formation, which sets an upper limit on the maximum possible family age.
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  • The population of rotational fission clusters inside asteroid collisional families

    Carruba, V.   Spoto, F.   Barletta, W.   Aljbaae, S.   Fazenda, A. L.   Martins, B.  

    Asteroid families are groups of objects sharing similar orbits. They are mostly the results of past collisions between two asteroids. Recent studies have shown that some asteroid families can also be the outcome of the spin-up-induced fission of a critically rotating parent body (fission clusters). In at least four young fission clusters, more than 5% of their members belong to subfamilies, secondary clusters of objects mostly formed after the main fission event. However, asteroidal subfamilies are still not well characterized. In this work, using family recognition methods based on time-reversal dynamical simulations, machine-learning clustering algorithms and the exceptional orbit accuracy obtained from Gaia observations of Solar System objects, we identify several subclusters within four extremely young collisional families. We find that collisional asteroid families younger than 100 Myr have a higher fraction of young detectable fission subclusters with respect to older groups. The collisional events that form asteroid families may trigger a subsequent cascade of spin-induced formations of fission clusters by producing fragments in highly rotating states. Asteroid families created by collisions in the last ~100 Myr have a higher fraction of subfamilies than older ones. The impact produces highly rotating fragments that generate such subfamilies by fission and subsequently disperse. The final appearance of an asteroid family is thus the product of a drawn-out evolution.
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  • Critical issues in low energy muon colliders-a summary

    Chattopadhyay, S.   Barletta, W.   Maury, S.   Neuffer, D.   Ruggiero, A.   Sessler, A.  

    We present a brief summary of the current state of conception and understanding of the accelerator physics issues for low energy muon colliders envisioned as Higgs factories, associated technological challenges and future research directions on this topic
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  • Educating and Training Accelerator Scientists and Technologists for Tomorrow

    Barletta, W.   Chattopadhyay, S.   Seryi, A.  

    Accelerator science and technology is inherently an integrative discipline that combines aspects of physics, computational science, electrical and mechanical engineering. As few universities offer full academic programs, the education of accelerator physicists and engineers for the future has primarily relied on a combination of on-the-job training supplemented with intensive courses at regional accelerator schools. This article describes the approaches being used to satisfy the educational curiosity of a growing number of interested physicists and engineers.
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  • Beam dynamics simulation for the high intensity DAE delta ALUS cyclotrons

    Yang, J. J.   Adelmann, A.   Barletta, W.   Calabretta, L.   Calanna, A.   Campo, D.   Conrad, J. M.  

    In the DAE delta ALUS (Decay-At-rest Experiment for delta(CP) studies At the Laboratory for Underground Science) project, high power H-2(+) cyclotron chains are proposed to efficiently provide proton beams with a kinetic energy of 800 MeV and an average power in the MW range. Space charge plays a pivotal role in both the injector and the ring cyclotrons. Large-scale particle simulations show that the injector cyclotron is a space charge dominated cyclotron and that a 5 mA beam current can be extracted with tolerable beam losses on the septum. In contrast, in the ring cyclotron, no space charge induced beam loss is observed during acceleration and extraction. (C) 2012 Elsevier B.V. All rights reserved.
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  • PEP-II design update and R&D results

    Barletta, W.   Zisman, M.S.   Bell, R.A.   Dorfan, J.M.  

    We describe the present status of the PEP-II asymmetric B factory design undertaken by SLAC, LBL, and LLNL. Design optimization and changes from the original CDR are described. R&D activities have focused primarily on the key technology areas of vacuum, RF, and feedback system design. Recent progress in these areas is described. The R&D results have verified our design assumptions and provide further confidence in the design of PEP-II.
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