56244495
Progress in the construction and testing of the 70 mm aperture quadrupole for the LHC low-b insertions
This paper reviews the current status and development of the one meter model of the 70 mm aperture quadrupole for the LHC low-p insertions. We describe the problems that were encountered in insulating the cable with an all Kapton system, the manufacture of the shaped end spacers, and coil winding and curing. We also present results of the short mechanical model of the magnet straight section which confirmed the soundness of the structural design and proved the tooling for the final magnet assembly.
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. >
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.
115309009
Quench and Mechanical Behaviour of an LHC Low-$\beta$ Quadrupole Model
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>>
9053540
Dynamical Supersymmetry Breaking and the Linear Multiplet
We analyze gaugino condensation in the presence of a dilaton and an antisymmetric tensor field, with couplings reminiscent of string theories. The degrees of freedom relevant to a supersymmetric description of the effective theory below the scale of condensation are discussed in this context.
118307813
LHC Phenomenology for String Hunters
Abstract 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 discuss possible signals of string physics at the Large Hadron Collider (LHC). In previous works, direct channel excitations of Regge recurrences in parton–parton scattering supplied the outstanding new signature. The present work considers the deviation from standard model expectations for the 4-fermion processes q q → q q and q q ′ → q q ′ , in which the s -channel excitation of string resonances is absent. In this case, we find that Kaluza–Klein recurrences at masses somewhat less than the string scale generate effective 4-fermion contact terms which can significantly enhance the dijet R ratio above its QCD value of about 0.6. The simultaneous observation of a nearby resonant structure in the dijet mass spectrum would provide a “smoking gun” for TeV scale string theory. In this work, we also show that (1) for M string 3.5 TeV , the rates for various topologies arising from the p p → Z 0 + jet channel could deviate significantly from standard model predictions and (2) that the sizeable cross sections for Regge recurrences can allow a 6 σ discovery for string scales as large as 3 TeV after about 1 year of LHC operation at s = 10 TeV and ∫ L d t ∼ 100 pb − 1 .
118625902
The LHC string Hunter's companion
Abstract The mass scale of fundamental strings can be as low as few TeV / c 2 provided that spacetime extends into large extra dimensions. We discuss the phenomenological aspects of weakly coupled low mass string theory related to experimental searches for physics beyond the Standard Model at the Large Hadron Collider (LHC). We consider the 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. We focus on the model-independent, universal features of low mass string theory. We compute, collect and tabulate the full-fledged string amplitudes describing all 2 → 2 parton scattering subprocesses at the leading order of string perturbation theory. We cast our results in a form suitable for the implementation of stringy partonic cross sections in the LHC data analysis. The amplitudes involving four gluons as well as those with two gluons plus two quarks do not depend on the compactification details and are completely model-independent. They exhibit resonant behavior at the parton center of mass energies equal to the masses of Regge resonances. The existence of these resonances is the primary signal of string physics and should be easy to detect. On the other hand, the four-fermion processes like quark–antiquark scattering include also the exchanges of heavy Kaluza–Klein and winding states, whose details depend on the form of internal geometry. They could be used as “precision tests” in order to distinguish between various compactification scenarios.
119896840
Hidden sectors with hidden matter
Abstract Using previous results on non-perturbative effects in massive supersymmetric Yang-Mills theories, we extend recent considerations on the duality invariant gaugino condensation, within the string effective action approach, to the formation of hidden matter field condensates. The masses of the condensing matter fields are determined by some string background parameters corresponding to vacuum expectation values of additional gauge singlet hidden matter fields. The vacuum degeneracy of these fields is shown to be lifted by non-perturbative condensation effects.
119845867
D-branes, SUSY breaking, and moduli stabilization
This is a brief introduction to the orientifold constructions leading to chiral models with partial (or complete) SUSY breaking at zero vacuum energy. The basic ingredients are D-branes and flux configurations that freeze the moduli vacuum expectation values and thus stabilize the size and shape of the compact dimensions. PACS: PACS-key11.25.Mj