646 research outputs found

    Update On The Code Intercomparison and Benchmark For Muon Fluence and Absorbed Dose Induced By An 18-GeV Electron Beam After Massive Iron Shielding

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    In 1974, Nelson, Kase and Svensson published an experimental investigation on muon shielding around SLAC high-energy electron accelerators. They measured muon fluence and absorbed dose induced by 14 and 18 GeV electron beams hitting a copper/water beamdump and attenuated in a thick steel shielding. In their paper, they compared the results with the theoretical models available at that time. In order to compare their experimental results with present model calculations, we use the modern transport Monte Carlo codes MARS15, FLUKA2011 and GEANT4 to model the experimental setup and run simulations. The results are then compared between the codes, and with the SLAC data.Comment: 14 pp. Presented paper at the 13th Meeting of the task-force on Shielding aspects of Accelerators, Targets and Irradiation Facilities (SATIF-13), HZDR, October 10-12, 2016, Dresden, Germany. arXiv admin note: substantial text overlap with arXiv:1502.0168

    Successful Coronary Stent Retrieval From a Pedal Artery

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    The purpose of this article is to report complications from a coronary drug-eluting stent lost in the peripheral circulation. We report the case of successful retrieval of a sirolimus coronary stent from a pedal artery in a young patient who underwent coronary angiography for previous anterior myocardial infarction. Recognition of stent embolization requires adequate removal of the device to avoid unwelcome clinical sequelae. Keywords Coronary stent Microsnare technique Peripheral embolization Stent retrieva

    Carotid artery stenting: a single-centre experience with up to 8 years' follow-up

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    Carotid artery stenting (CAS) may be an alternative to surgical endoarterectomy not only in high-risk patients. We report results in the endovascular treatment of carotid artery disease with up to 8 years' follow-up. In this retrospective study, we analysed data from 853 consecutive patients (946 arteries) treated for carotid artery stenosis between April 1999 and March 2007; 491 (52%) arteries were symptomatic and 455(48%) were asymptomatic. Preprocedural evaluation of the patients was performed with echo Doppler, magnetic resonance angiography (MRA) or computed tomographic angiography (CTA) and a neurological examination. A cerebral protection device was used in 879 (92.9%) procedures. Anti-platelet therapy was administered before and after the procedure. All patients were included in a follow-up of up to 8 years. Technical success was achieved in 943 (99.6%) lesions. At 30 days, there was a 0.21% (n = 2) death rate, a 0.42% major stroke rate, a 1.69% minor stroke/transient ischaemic attack (TIA) rate and a combined 2.32% TIA/stroke and death rate. During follow-up, echo Doppler evidenced restenosis in 39 (4.85%) cases; of these, only five, presenting restenosis > 80%, were treated with an endovascular reintervention. At the long-term follow-up, two strokes (0.23%) were reported, which both occurred within the first 2 years. In our experience, carotid artery stenting seems to be a safe and effective treatment, providing satisfactory long-term clinical results

    Present Status and Future Programs of the n_TOF Experiment

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    This is an Open Access article distributed under the terms of the Creative Commons Attribution-Noncommercial License 3.0, which permits unrestricted use, distribution, and reproduction in any noncommercial medium, provided the original work is properly citedThe neutron time-of-flight facility n_TOF at CERN, Switzerland, operational since 2001, delivers neutrons using the Proton Synchrotron (PS) 20 GeV/c proton beam impinging on a lead spallation target. The facility combines a very high instantaneous neutron flux, an excellent time of flight resolution due to the distance between the experimental area and the production target (185 meters), a low intrinsic background and a wide range of neutron energies, from thermal to GeV neutrons. These characteristics provide a unique possibility to perform neutron-induced capture and fission cross-section measurements for applications in nuclear astrophysics and in nuclear reactor technology.The most relevant measurements performed up to now and foreseen for the future will be presented in this contribution. The overall efficiency of the experimental program and the range of possible measurements achievable with the construction of a second experimental area (EAR-2), vertically located 20 m on top of the n_TOF spallation target, might offer a substantial improvement in measurement sensitivities. A feasibility study of the possible realisation of the installation extension will be also presented

    A global fit to determine the pseudoscalar mixing angle and the gluonium content of the eta' meson

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    We update the values of the eta-eta' mixing angle and of the eta' gluonium content by fitting our measurement R_phi = BR(phi to eta' gamma)/ BR(phi to eta gamma) together with several vector meson radiative decays to pseudoscalars (V to P gamma), pseudoscalar mesons radiative decays to vectors (P to V gamma) and the eta' to gamma gamma, pi^0 to gamma gamma widths. From the fit we extract a gluonium fraction of Z^2_G = 0.12 +- 0.04, the pseudoscalar mixing angle psi_P = (40.4 +- 0.6) degree and the phi-omega mixing angle psi_V = (3.32 +- 0.09) degree. Z^2_G and psi_P are fairly consistent with those previously published. We also evaluate the impact on the eta' gluonium content determination of future experimental improvements of the eta' branching ratios and decay width.Comment: 13 pages, 7 figures to submit to JHE

    Towards the high-accuracy determination of the 238U fission cross section at the threshold region at CERN - N-TOF

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    The 238U fission cross section is an international standard beyond 2 MeV where the fission plateau starts. However, due to its importance in fission reactors, this cross-section should be very accurately known also in the threshold region below 2 MeV. The 238U fission cross section has been measured relative to the 235U fission cross section at CERN - n-TOF with different detection systems. These datasets have been collected and suitably combined to increase the counting statistics in the threshold region from about 300 keV up to 3 MeV. The results are compared with other experimental data, evaluated libraries, and the IAEA standards

    A Study of the Radiative Ke3 Decay and Search for Direct Photon Emission with the KLOE Detector

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    We present a measurement of the ratio R = \Gamma(\keg;\Estar>30\mev,\qstar>20^\circ)//\Gamma(\kegf)andafirstmeasurementofthedirectemissioncontributioninKLsemileptonicdecays.ThemeasurementisdoneattheDAFNEphifactoryselectingphi>KLKSdecayswiththeKLOEdetector.Weuse328pb1 and a first measurement of the direct emission contribution in KL semileptonic decays. The measurement is done at the DAFNE phi-factory selecting phi->KL KS decays with the KLOE detector. We use 328 pb^{-1} of data corresponding to about 3.5 million Ke3(g) events and about 9000 radiative events. Our result is R=(924 +/- 23(stat) +/-16(syst)10^{-5} for the branching ratio and X=-2.3 +/- 1.3(stat) +/- 1.4(syst) for the parameter describing direct emission.Comment: 8 pages, 7 figure

    Measurement of the K_L \to \pi\mu\nu form factor parameters with the KLOE detector

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    Using 328 pb^{-1}of data collected at DAFNE corresponding to \sim 1.8 million KLπμνK_L\to \pi\mu\nu decays, we have measured the Kμ3K_{\mu 3} form factor parameters. The structure of the KπK-\pi vector-current provides information about the dynamics of the strong interaction; its knowledge is necessary for evaluation of the phase-space integral required for measuring the CKM matrix element VusV_{us} and for testing lepton universality in kaon decays. Using a new parametrization for the vector and scalar form factors, we find λ+\lambda_+=\pt(25.7\pm 0.6),-3, and λ0\lambda_0=\pt(14.0\pm 2.1),-3,. Our result for λ0\lambda_0, together with recent lattice calculations of fπf_\pi, fKf_K and f(0)f(0), satisfies the Callan-Trieman relatio
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