| 1. |
- Aaron, F. D., et al.
(författare)
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Multi-leptons with high transverse momentum at HERA
- 2009
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Ingår i: Journal of High Energy Physics. - : Springer Science and Business Media LLC. - 1029-8479. ; :10
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Tidskriftsartikel (refereegranskat)abstract
- Events with at least two high transverse momentum leptons (electrons or muons) are studied using the H1 and ZEUS detectors at HERA with an integrated luminosity of 0.94 fb(-1). The observed numbers of events are in general agreement with the Standard Model predictions. Seven di- and tri-lepton events are observed in e(+)p collision data with a scalar sum of the lepton transverse momenta above 100 GeV while 1.94 +/- 0.17 events are expected. Such events are not observed in e(-)p collisions for which 1.19 +/- 0.12 are predicted. Total visible and differential di-electron and di-muon photoproduction cross sections are extracted in a restricted phase space dominated by photon-photon collisions.
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| 2. |
- Beurskens, M. N. A., et al.
(författare)
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Pedestal width and ELM size identity studies in JET and DIII-D; implications for ITER
- 2009
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Ingår i: Plasma Physics and Controlled Fusion. - : IOP Publishing. - 0741-3335 .- 1361-6587. ; 51:12, s. 124051-
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Tidskriftsartikel (refereegranskat)abstract
- The dependence of the H-mode edge transport barrier width on normalized ion gyroradius (rho* = rho/a) in discharges with type I ELMs was examined in experiments combining data for the JET and DIII-D tokamaks. The plasma configuration as well as the local normalized pressure (beta), collisionality (nu*), Mach number and the ratio of ion and electron temperature at the pedestal top were kept constant, while rho* was varied by a factor of four. The width of the steep gradient region of the electron temperature (T-e) and density (n(e)) pedestals normalized to machine size showed no or only a weak trend with rho*. A rho(1/2) or rho(1) dependence of the pedestal width, given by some theoretical predictions, is not supported by the current experiments. This is encouraging for the pedestal scaling towards ITER as it operates at lower rho* than existing devices. Some differences in pedestal structure and ELM behaviour were, however, found between the devices; in the DIII-D discharges, the n(e) and T-e pedestal were aligned at high rho* but the ne pedestal shifted outwards in radius relative to T-e as rho* decreases, while on JET the profiles remained aligned while rho* was scanned by a factor of two. The energy loss at an ELM normalized to the pedestal energy increased from 10% to 40% as rho* increased by a factor of two in the DIII-D discharges but no such variation was observed in the case of JET. The measured pedestal pressures and widths were found to be consistent with the predictions from modelling based on peeling-ballooning stability theory, and are used to make projections towards ITER
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| 3. |
- Salinas, Ener, 1957, et al.
(författare)
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A new technique for reducing extremely low frequency magnetic field emissions affecting large building structures
- 2007
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Ingår i: Environmentalist. - 0251-1088 .- 1573-2991. ; 27:4, s. 571-576
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Tidskriftsartikel (refereegranskat)abstract
- When large structures such as residentialcompounds or public buildings are under the influence ofextremely low frequency (ELF) magnetic fields, such asthe one generated by a system of railways fed by16.67 Hz, standard methods of designing shieldingstructures by numerical methods usually fail. The lattercan be explained by the difficulty posed in the computingprocess by the large aspect ratios involved due to thinlayers of metal (a few millimetres or centimetres) incontrast to the large dimensions of the affected structure(several tens of meters). In some cases one has to utilizespecial approximations such as surface conductivity,which are not easy to handle when the designed shieldingstructure is clearly three -dimensional. Other alternativessuch as experimentation in situ are very costly. Here, anew technique is presented of mitigating the field byusing three-dimensional propagation of induced currentsoptimizing the field reduction factors and minimizing thecost of shielding material. The particular designingmethod is a hybrid of numerical simulations combinedwith lab experimentation using scaled models of the largestructure. The method is rather cost-effective and flexible as various designs can be easily tested. Results are presented in the form of magnetic field values, at various locations in the buildings, before and after this mitigation technique is applied.
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