115712937
The polarization wigglers in LEP
Twelve strong wigglers, primarily intended to increase t.he polarization rate and level, were iustallcd in I.I?P during the 1990-91 shutdown. Al injection energy in particular, the effects of synchrotron radiat.iou in t,hesfl wigglers c.ompletely dominate those from the rest, of tlrc, rirlg. Tllikir design and commiGouing are dcscribt,d Among several applications, the substantial cont~rolled tturictl-li,ngttlf~r~irlg of which they are capable has proved to bcs import,allt, iI1 increasing the intensit,y of the LI?P beams. ‘1’11~ rnensured effects of the wigglt%rs 011 thr, beams and VafuIIril iir(’ conipared with theoretical pretlic.tious.
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.
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
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>>
120401055
Dilaton Couplings at Large Distances
Abstract The large-distance behaviour of dilaton couplings is studied within the framework of four-dimensional heterotic superstring theories. String loop corrections violate universality of dilaton and graviton couplings, increasing dilaton couplings at large distances. This implies a serious problem for string theories, unless a non-zero dilaton mass is generated.
55652361
Jet signals for low mass strings at the LHC
The mass scale Ms of superstring theory is an arbitrary parameter that can be as low as few TeVs if the Universe contains large extra dimensions. We propose a search for the effects of Regge excitations of fundamental strings at LHC, in the process pp → γ + jet. The underlying parton process is dominantly the single photon production in gluon fusion, gg → γg, with open string states propagating in intermediate channels. If the photon mixes with the gauge boson of the baryon number, which is a common feature of D-brane quivers, the amplitude appears already at the string disk level. It is completely determined by the mixing parameter – and it is otherwise model-(compactification-) independent. Even for relatively small mixing, 100 fb−1 of LHC data could probe deviations from standard model physics, at a 5σ significance, for Ms as large as 3.3 TeV.
20156101
Threshold Effects Beyond the Standard Model
In this contribution to the Festschrift celebrating Gabriele Veneziano on his 65th birthday, I discuss the threshold effects of extra dimensions and their applications to physics beyond the standard model, focusing on superstring theory.
123238576
Light composite supermultiplets
Abstract It is argued that in a wide class of massless strongly interacting supersymmetric gauge theories there exist confining phases with unbroken supersymmetry. We explain how to identify and interpret the light composite supermultiplet content of these phases.
14313920
Fermion masses in superstring theory
We give a model-independent discussion of fermion masses in four-dimensional heterotic superstring theories. We discuss the tree level contributions and quantum corrections, including one-loop threshold effects and masses generated as a result of non-perturbative supersymmetry breaking. We also point out that superstring models give rise to a generic μ -term in the effective low energy Lagrangian.