2,356 research outputs found

    Present challenges in hadrontherapy techniques

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    Hadrontherapy is a high-precision technique in cancer radiation therapy, which allows obtaining a superior conformal treatment with respect to photons used in conventional radiation therapy. To reach this ambitious goal without reducing the patient throughput needed in a hospital-based environment, the physical and radiobiological properties of charged hadrons, protons and carbon ions in particular, have to be exploited at best, making use of the most modern technologies issued from research in nuclear and particle physics. In the present days, we are assisting to a continuous technological challenge, leading to the conception and to the development of innovative methods and instruments. In this paper, the most relevant challenges in dose delivery systems, gantries, imaging, quality assurance and particle accelerators are reviewe

    Conformality and Gauge Coupling Unification

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    It has been recently proposed to embed the standard model in a conformal gauge theory to resolve the hierarchy problem, and to avoid assuming either grand unification or low-energy supersymmetry. By model building based on string-field duality we show how to maintain the successful prediction of an electroweak mixing angle with sin2θ0.231sin^2\theta \simeq 0.231 in conformal gauge theories with three chiral families.Comment: 8 pages LaTe

    The Paths of Unification In The GUST With The G x G Gauge Groups of E(8) x E(8)

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    In the framework of the four dimensional heterotic superstring with free fermions we discuss the rank eight and/or sixteen Grand Unified String Theories (GUST) which contain the SU(3)_H - gauge family symmetry. We explicitly investigate the paths of the unification in the GUST with gauge symmetry G x G = [SU(5) x U(1) x (SU(3) x U(1))_H]^2. We show that the GUSTs with the G x G gauge group allow to make the scale of unification to be consistent with the string scale M_SU = g_{string} * 5 * 10^17 GeV.Comment: 18 pages, 2 Postscript figures, uses epsf.st

    High-power test results of a 3 GHz single-cell cavity

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    Compact, reliable and little consuming accelerators are required for the treatment of tumours with ions. TERA proposes the "cyclinac", composed of a high-frequency, fast-cycling linac which boosts the energy of the particles previously accelerated in a cyclotron. The dimensions of the linac can be reduced if high gradients are used. TERA initiated a high-gradient test program to understand the operational limit of such structures. The program foresees the design, prototyping and high-power test of several high-gradient structures operating at 3 and 5.7 GHz. The high-power tests of the 3 GHz single-cell cavity were completed in Winter 2012. The maximum BDR threshold measured for Emax of 170 MV/m and RF pulses of 2.5 \mu s was 3 x 10-6 bpp/m

    Comment On ``Grand Unification and Supersymmetric Threshold"

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    Barbieri and Hall have argued that threshold effects at the scale of grand-unification wipe out predictions on the SUSY scale, M_S. Using triviality arguments we give upper bounds on ultraheavy particles, while proton stability gives lower bounds on the mass of the higgs color-triplet. We find no useful lower bound on the Σ\Sigma supermultiplet, but if the strong coupling constant is as large as recent experiments suggest, unification in the minimal SUSY SU(5) model requires that the SigmaSigma masses be 107MV\sim 10^{-7}M_V and that the color octet and weak triplet be split in mass by a factor of \sim100.Comment: 6 pages (revised

    Phenomenological Analysis of pppp and pˉp\bar{p}p Elastic Scattering Data in the Impact Parameter Space

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    We use an almost model-independent analytical parameterization for pppp and pˉp\bar{p}p elastic scattering data to analyze the eikonal, profile, and inelastic overlap functions in the impact parameter space. Error propagation in the fit parameters allows estimations of uncertainty regions, improving the geometrical description of the hadron-hadron interaction. Several predictions are shown and, in particular, the prediction for pppp inelastic overlap function at s=14\sqrt{s}=14 TeV shows the saturation of the Froissart-Martin bound at LHC energies.Comment: 15 pages, 16 figure

    MSSM and Large tanβtan\beta from SUSY Trinification

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    We construct a supersymmetric model based on the semi-simple gauge group SU(3)c×SU(3)L×SU(3)RSU(3)_c \times SU(3)_L \times SU(3)_R with the relation tanβmt/mbtan\beta \simeq m_t/m_b automatically arising from its structure. The model below a scale 1016\sim 10^{16} GeV gives naturally rise just to the minimal supersymmetric standard model and therefore to the presently favored values for sin2θwsin^2 \theta_w and αs\alpha_s without fields in representations higher than the fundamental.Comment: 9 pages, LaTeX, UT-STPD-3-9

    Neutrino masses and flavor symmetries

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    The problem of neutrino masses and mixing angles is analysed in a class of supersymmetric grand unified models, with SO(10) gauge symmetry and global U(2) flavour symmetry. Adopting the seesaw mechanism for the generation of the neutrino masses, one obtains a mass matrix for the left-handed neutrinos which is directly related to the parameters of the charged sector, while the unknown parameters of the right-handed Majorana mass matrix are inglobed in a single factor.Comment: 17 pages, 1 eps figure, uses graphicx.sty, LaTeX 2e, to be published on "Il Nuovo Cimento

    Consistency Conditions for AdS/CFT Embeddings

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    The group embeddings used in orbifolding the AdS/CFT correspondence to arrive at quiver gauge field theories are studied for both supersymmetric and non-supersymmetric cases. For an orbifold AdS5×S5/ΓAdS_5 \times S^5/\Gamma the conditions for embeddings of the finite group Γ\Gamma in the SU(4)O(6)SU(4) \sim O(6) isotropy of S5S^5 are stated in the form of consistency rules, both for Abelian and Non-Abelian Γ\Gamma.Comment: 10 pages LaTe

    EuCARD Newsletter Issue 3

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    European Coordination for Accelerator Research and Development (EuCARD) Newsletter Issue 3: October - December 2009 * A word on behalf of the Steering Committee * Cryocatcher in the GSI * Strategy and the Spallation Source * Accelerators for hadron therapy * For EuCARD members: publication
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