115171795
Development of a superconducting insertion quadrupole model magnet for the Large Hadron Collider
121954895
Test results of a variant-design LHC twin-aperture dipole magnet
Since 1989, KEK and CERN carried out jointly an experimental program in the frame of the R&D work for the LHC main dipole. The mechanical structure of this design is based on a separate coil/collar and "horizontally split iron" concept. A total of four single aperture and two twin-aperture 1 m long dipole magnets were built. The last twin-aperture magnet was tested at CERN, reaching a maximum field of 9.55 T at 1.9 K. This paper reports the magnet training performance and quench localization at 1.9 K and 4.5 K. The performance as a function of current ramp rate and measurements of the field quality are also reported.
121851945
Design, test and performance of the prototype superconducting quadrupole for the LEP low-beta insertions
The prototype of the superconducting quadrupoles for the low-beta insertions at the Large Electron-Positron collider has been tested successfully. This industry-built quadrupole, which has a warm bore of 130 mm and a magnetic length of 2 m, is required to provide a gradient of 36 T/m over a field aperture of 1000 mm diameter. It achieved its maximum operating current without training. While retaining the main characteristics of its ISR predecessors, the design of this magnet incorporates several novel features, due to constraints imposed by the environment of the LEP experiments. In particular the quadrupole is slender and ironless, and has a horizontally oriented cryogenic service funnel. Following a description of the major aspects of the design, the results are given of the magnetic and cryogenic tests and measurements. >
20721233
A design concept for the LHC insertion quadrupoles
It is noted that the low- beta insertion optics imposes severe constraints on the desired characteristics of the local quadrupoles. In order to obtain the necessary degree of focusing at the LHC (Large Hadron Collider), triplets made up of four 250 T/m superconducting quadrupoles, about 6- to 7-m long, are presently envisaged. The large value of the betatron functions through these magnets is such that, besides being the principal source of chromatic aberrations, errors in their gradient will also contribute significantly to the excitation of resonance in the circulating beams. The magnets should therefore provide a gradient field of very high quality. The relatively small number of quadrupoles involved means that the cost constraints are less binding on these than on the lattice magnets. Their single aperture also opens up the possibility of an approach different from that adopted for the regular twin-aperture quadrupoles. One of the design concepts being investigated involves the use of flat cable wound in rectangular blocks to approximate the required quadrupole producing current density. The characteristics of the magnet are described, as is the method of applying the required prestress to the winding.<<ETX>>
115309009
Quench and Mechanical Behaviour of an LHC Low-$\beta$ Quadrupole Model
123424297
The Choice of Spectrometer Magnets for LEP
Many experiments at LEP will require matching spectrometer magnets. In this report, guidelines are established for providing a starting point in the iterative process of choosing the best device for a particular detector. Magnets are compared in terms of their resolving power based on measurements of sagitta. This approach draws attention to the importance of detector size, and also helps to define the preferred areas of application of normal and superconducting technology. Although most emphasis is placed on the solenoid, toroids and dipoles are also discussed.
11234097
Amplitude for N-gluon superstring scattering.
We consider scattering processes involving N gluonic massless states of open superstrings with a certain Regge slope alpha'. At the semiclassical level, the string world-sheet sweeps a disk and N gluons are created or annihilated at the boundary. We present exact expressions for the corresponding amplitudes, valid to all orders in alpha', for the so-called maximally helicity violating configurations, with N = 4, 5 and N = 6. We also obtain the leading O(alpha '2) string corrections to the zero-slope N-gluon Yang-Mills amplitudes.
17650407
The LHC String Hunter's Companion (II): Five-particle amplitudes and universal properties
Abstract We extend the study of scattering amplitudes presented in “The LHC String Hunter's Companion” [1] to the case of five-point processes that may reveal the signals of low mass strings at the LHC and are potentially useful for detailed investigations of fundamental Regge excitations. In particular, we compute the full-fledged string disk amplitudes describing all 2 → 3 parton scattering subprocesses leading to the production of three hadronic jets. We cast our results in a form suitable for the implementation of stringy partonic cross sections in the LHC data analysis. We discuss the universal, model-independent features of multi-parton processes and point out the existence of even stronger universality relating N-gluon amplitudes to the amplitudes involving N − 2 gluons and one quark–antiquark pair. We construct a particularly simple basis of two functions describing all universal five-point amplitudes. We also discuss model-dependent amplitudes involving four fermions and one gauge boson that may be relevant for studying jets associated to Drell–Yan pairs and other processes depending on the spectrum of Kaluza–Klein particles, thus on the geometry of compact dimensions.
14649838
RR flux on Calabi–Yau and partial supersymmetry breaking
Abstract We show how turning on Flux for RR (and NS-NS) field strengths on non-compact Calabi–Yau 3-folds can serve as a way to partially break supersymmetry from N=2 to N=1 by mass deformation. The freezing of the moduli of Calabi–Yau in the presence of the flux is the familiar phenomenon of freezing of fields in supersymmetric theories upon mass deformations.
14055711
Duality of N = 2 heterotic-type I compactifications in four dimensions
We discuss type I-heterotic duality in four-dimensional models obtained as a Coulomb phase of the six-dimensional U(16) orientifold model compactified on T2 with arbitrary SU(16) Wilson lines. We show that Kahler potentials, gauge threshold corrections and the infinite tower of higher derivative F-terms agree in the limit that corresponds to weak coupling, large T2 heterotic compactifications. On the type I side, all these quantities are completely determined by the spectrum of N = 2 BPS states that originate from D = 6 massless superstring modes.
44222589
String Phenomenology at the LHC
We consider extensions of the standard model based on open strings ending on D-branes, with gauge bosons due to strings attached to stacks of D-branes and chiral matter due to strings stretching between intersecting D-branes. Assuming that the fundamental string mass scale is in the TeV range and the theory is weakly coupled, we review possible signals of string physics at the Large Hadron Collider.