338 research outputs found
Low loss Nb-Ti superconducting Rutherford cable manufacture for the SIS 300 INFN model dipole
No full textThe INFN (Istituto Nazionale di Fisica Nucleare, Italy) has launched in 2006 the DISCORAP (DIpoli SuperCOnduttori RApidamente Pulsati, or fast-pulsed superconducting dipoles) project which foresees the design, manufacture and test of a fast cycled (1 T/s) 4.5 T, cosθ , dipole model for the SIS 300 synchrotron of the FAIR (Facility for Antiproton and Ion Research) facility at GSI (Darmstadt, Germany). This magnet is now close to completion at ASG company (Genova, Italy); it is based on a Rutherford cable, manufactured by Luvata Superconductors, which incorporates several technologies to reduce the AC losses, namely a Nb-Ti filament diameter around 3 μm, Cu 0.5wt%Mn interfilamentary matrix and a Rutherford cable with stainless steel core. The development of the Rutherford foresees two subsequent generations of Rutherford cables, aimed to reach the demanding goals of the SIS-300 specifications in steps. In this paper we present the results of the manufacture of the first generation Rutherford cable, and the assessment of its electromagnetic performances, including critical current density, twist pitch impact on critical current degradation, filament hysteresis and deformation, transverse resistivity, Cu-Mn paramagnetism
Triggers for displaced decays of long-lived neutral particles in the ATLAS detector
No full textA set of three dedicated triggers designed to detect long-lived neutral particles decaying throughout the ATLAS detector to a pair of hadronic jets is described. The efficiencies of the triggers for selecting displaced decays as a function of the decay position are presented for simulated events. The effect of pile-up interactions on the trigger efficiencies and the dependence of the trigger rate on instantaneous luminosity during the 2012 data-taking period at the LHC are discussed
Measurement of the WW cross section in √s = 7 TeV pp collisions with the ATLAS detector and limits on anomalous gauge couplings
No full textThis Letter reports a measurement of the WW production cross section in
√
s = 7 TeV pp collisions
using data corresponding to an integrated luminosity of 1.02 fb−1 collected with the ATLAS detector.
Using leptonic decays of oppositely charged W bosons, the total measured cross section is σ(pp →
WW) = 54.4 ± 4.0 (stat.) ± 3.9 (syst.) ± 2.0 (lumi.) pb, consistent with the Standard Model prediction
of σ(pp→WW) = 44.4±2.8 pb. Limits on anomalous electroweak triple-gauge couplings are extracted
from a fit to the transverse-momentum distribution of the leading charged lepton in the even
AC Losses Measurement of the DISCORAP Model Dipole Magnet for the SIS 300 Synchrotron at FAIR
No full textConsiderable attention has been paid in the last years to the development of fast-cycled superconducting magnets for future accelerators, leading to the design and construction by INFN and GSI of a 3.8-m-long prototype of a 4.5 T, 1 T/s, dipole magnet, for the SIS300 synchrotron of the FAIR facility (Darmstadt, Germany). This ramp-rate is 20-100 times higher than the one used in other superconducting synchrotrons like RHIC or LHC. Being operated at rather large dI/dt, these magnets are subjected to a wide spectrum of ac dissipation, taking place in the superconductor as well as in the metallic components of the mechanical structure, requiring the development of specialized superconducting cables and a careful consideration of the other aspects of the structural design. Between July and September 2012, the dipole magnet prototype has been subjected to a test at LASA laboratory (INFN Milan, Italy), during which it was successfully operated at current ramp rates as high as 0.7 T/s (the power supply limit). In this paper, we describe the V-I apparatus used to assess the dissipations within the magnet during the ac regime, the measurement results, and their comparison with the values expected from the design and on the basis of superconducting cable qualification results
Search for heavy vector-like quarks coupling to light quarks in proton–proton collisions at √s = 7 TeV with the ATLAS detector
No full text<p>This Letter presents a search for singly produced vector-like quarks, Q, coupling to light quarks, <i>q</i>. The search is sensitive to both charged current (CC) and neutral current (NC) processes, <i>pp→Qq→Wqq′</i> and <i>pp→Qq→Zqq′</i> with a leptonic decay of the vector gauge boson. In 1.04 fb<sup>−1</sup> of data taken in 2011 by the ATLAS experiment at a center-of-mass energy √s = 7 TeV, no evidence of such heavy vector-like quarks is observed above the expected Standard Model background. Limits on the heavy vector-like quark production cross section times branching ratio as a function of mass mQ are obtained. For a coupling <sub>κq</sub>Q=v/mQ, where <i>v</i> is the Higgs vacuum expectation value, 95% C.L. lower limits on the mass of a vector-like quark are set at 900 GeV and 760 GeV from CC and NC processes, respectively.</p>
Field quality and losses for the 4.5 T superconducting pulsed dipole of SIS300
No full textThis paper presents the 2-D design of the SIS300 synchrotron dipole of the FAIR facility at GSI. The dipole has a length of 7.8 m, a field of 4.5 T, in a 100 mm bore, and is ramped at 1 T/s. The studies are performed by INFN (Frascati, Genova and Milano-LASA) in a R&D collaboration with GSI. The program started in 2006 (DISCORAP) and has as a final goal the construction and test of a prototype. Particular emphasis is given to the study of the field quality and of the losses during the ramping of the magnet. Some calculation methods and different codes for magnet design are evaluated and compared
Search for stable hadronising squarks and gluinos with the ATLAS experiment at the LHC
No full textHitherto unobserved long-lived massive particles with electric and/or colour charge are predicted by a range of theories which extend the Standard Model. In this Letter a search is performed at the ATLAS experiment for slow-moving charged particles produced in proton–proton collisions at 7 TeV centre-of-mass energy at the LHC, using a data-set corresponding to an integrated luminosity of 34 pb−1. No deviations from Standard Model expectations are found. This result is interpreted in a framework of supersymmetry models in which coloured sparticles can hadronise into long-lived bound hadronic states, termed R-hadrons, and 95% CL limits are set on the production cross-sections of squarks and gluinos. The influence of R-hadron interactions in matter was studied using a number of different models, and lower mass limits for stable sbottoms and stops are found to be 294 and 309 GeV respectively. The lower mass limit for a stable gluino lies in the range from 562 to 586 GeV depending on the model assumed. Each of these constraints is the most stringent to date
Low-loss wire design for the DiSCoRaP dipole
No full textThe SIS-300 synchrotron of the new FAIR facility at GSI (Germany) will use fast-cycled superconducting magnets. Its dipoles will be pulsed at 1 T/s; for comparison, LHC is ramped at 0.007 T/s and RHIC at 0.042 T/s. Within the frame of a collaboration between INFN and GSI, INFN has funded the project DISCORAP (DIpoli SuperCOnduttori RApidamente Pulsati, or Fast Pulsed Superconducting Dipoles) whose goal is to design, construct and test a half-length (4 m), curved, model of one lattice dipole. This paper focuses on the low loss superconducting wire design, and in particular to the transverse resistivity calculations and the dynamic stability verification
Status of the Activity for the Construction of the HL-LHC Superconducting High Order Corrector Magnets at LASA-Milan
No full textINFN is developing at LASA Laboratory (Milano, Italy) the prototypes of five corrector magnets, from skew quadrupole to dodecapole, which will equip the high-luminosity interaction regions (IRs) of the High Luminosity-LHC (HL-LHC). These magnets are based on a superferric design, to allow a relatively simple, modular, and easy to construct magnet. This program takes place within the framework of a collaboration agreement between CERN and INFN. In this paper, we present an overview of the activity, from the design, to the construction and test at the operation condition
Technical design report of a superconducting model dipole for FAIR SIS300
No full textThis report deals with the R&D activities aimed at developing the high field rapidly-cycling super-conducting dipoles needed for SIS300 synchrotron of the FAIR facility at GSI. The present lattice design includes 48 long dipoles with magnetic length 7.757 m and 12 short dipoles with magnetic length 3.879 m. The coils have two main features: they are curved (the corresponding sagitta is 112.8 mm for long dipoles), and they are fast ramped (for a superconducting magnet). Both these characteristics demand a challenging R&D, aimed at the development of the required low loss conductor, a robust design with respect to fatigue issues and a suitable winding technology. The Italian National Institute of Nuclear Physics (INFN) is performing this R&D. A project, called DISCORAP (“Dipoli SuperCOnduttori RApidamente Pulsati”), started in 2006 in accordance with a specific INFN-FAIR Memorandum of Understanding signed by both institutions in December 2006. The aim is to have a complete cold mass model of the short dipole ready in the summer of 2009. After a preliminary test of the cold mass in a vertical cryostat, it will be integrated into a horizontal cryostat for a test series at GSI
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