The MINOS CollaborationArgonne -Athens -Caltech -Chicago -Dubna -Fermilab -Harvard IHEP-Beijing -Indiana -ITEP-Moscow -Lebedev Livermore VCL-London Minnesota -Oxford -Pittsburgh -Protvino -Rutherford -Stanford -SussexTexas A&M -Texas-Austin -Tufts -Western Washington - Executive summaryThe MINOS (Main Injector Neutrino Oscillation Search) experiment is designed to search for neutrino oscillations with a sensitivity significantly greater than has been achieved to date. The phenomenon of neutrino oscillations, whose existence has not been proven convincingly so far, allows neutrinos of one "flavor" (type) to slowly transform themselves into another flavor, and then back again to the original flavor, as they propagate through space or matter.The MINOS experiment is optimized to explore the region of neutrino oscillation "para meter space" (values of the !:l.m 2 and sin 2 29 parameters) suggested by previous investigations of atmospheric neutrinos: the Kamiokande, 1MB, Super-Kamiokande and Soudan 2 experi ments. The study of oscillations in this region with a neutrino beam from the Main Injector requires measurements of the beam after a very long flight path. This in turn requires an intense neutrino beam and a massive detector in order to have an adequate event rate at a great distance from the source.We propose to enhance significantly the physics capabilities of the MINOS experiment by the addition of a Hybrid Emulsion Detector at Soudan, capable of unambigous identification of the neutrino flavor. Recent developments in emulsion experiments make such a detector possible, although significant technological challenges must be overcome. We propose to initiate an R&D effort to identify major potential problems and to develop practical solutions to them.In addition to this primary motivation for this R&D work, we note that the strong and growing interest in studies of neutrino oscillations using neutrino beams from future muon storage rings provides another potential application. These beams will offer significantly higher intensities, albeit of mixed 1I1J-and lie, beams. In order to take full advantage of these beams for neutrino oscillation studies it will be necessary that the detector be capable of determination of the flavor of the final state lepton, and the lepton's charge in a significant fraction of the interactions. At present, an emulsion detector in an external magnetic field appears best suited to offer such capabilities. The R&D effort discussed here will be an important step towards a design of such a future detector. This document is organized as follows:• Chapter 1 summarizes the physics motivation for the proposed emulsion detector,• Chapter 2 briefly reviews the status of the emulsion technology and its aplication to particle physics experiments,• Chapter 3 discusses design considerations for an emulsion detector,• Chapter 4 describes some of the details of a possible detector as well as results from the work up to date,• Chapter 5 outlines the proposed R&D program and summarizes the resources req...

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A hybrid-coil NbJSn/Cu dipole is being developed for use in future hadron colliders. It features stress management within the coil, and the use of pure Cu strands within the coil to minimize the quantity of superconductor while providing quench protection. A first 7 Tesla NbTi model of the design has been built and will soon be tested.Two designs for the first NbJSn model have been prepared. In one version, the placement of coil blocks and the inside contour of the steel flux return are shaped to achieve colliderquality field over a 2O:l dynamic range of operating field. In the other version, the flux return provides a close-coupled planar boundary that suppresses persistent-current multipoles by a factor 20, and the same dynamic range is achieved using current programming of the inner and outer coil elements. Both versions use the least superconductor of any high-field collider dipole design.

A first model dipole is being built for a 16 Tesla blockcoil dipole for future hadron colliders. The design uses stress management: a support matrix that intercepts Lorentz stress between successive sections of the coil and bypasses it to prevent strain degradation of the superconductors and insulation. The block-coil methodology has also been used to design dipoles for 12 Tesla and 15 Tesla, in which the amount of superconductor is minimized by cabling copper stabilizer strands with superconductor strands. The 12 Tesla block-coil dipole requires only one-fifth as much superconductor as does a 12 Tesla cos θ dipole that is being developed elsewhere. INTRODUCTIONThe technology of superconducting dipoles determines the cost and performance of future hadron colliders. The field strength determines the relation between energy and circumference; the field quality and provisions for beam stability and synchrotron radiation determine the luminosity and lifetime of the colliding beams. Over the past several years much work has been done to relate the several requirements of a high-luminosity collider to the parameters of its magnets. A first example is synchrotron radiation. It was once thought that field strength beyond ~10 Tesla would create a problem from the heat deposited by synchrotron radiation in the cryogenic magnet. it is now realized that synchrotron radiation damping at high field strength can damp beam size and improve luminosity, and schema have been conceived (one presented below) whereby the synchrotron radiation can be absorbed at a higher temperature within the dipoles so that its refrigeration impact is reduced. A second example is aperture. It was once thought that an aperture radius of at least 2.5 cm was necessary to have acceptable growth times for single-beam and mode coupling instabilities. Several schema have been developed recently whereby such instabilities can be damped within a single turn, so that apertures as small as 1 cm can support stable beams. With presently available superconductors, the coil for a high-field dipole is thick compared to its inner radius, so that reducing aperture has the potential to dramatically reduce magnet cost. A third example is the impact of various multipoles upon beam growth mechanisms in a high-luminosity collider.With NbTi superconductor, it was possible to make strands with extremely small filament diameter (few µm) so that multipoles produced by persistent currents at injection energy were suppressed. NbTi cannot support fields higher than ~9 Tesla, and the superconductors that are used at higher fields (today Nb 3 Sn, in the future Bi-2212) currently have very large filament diameter (>50 µm) if fabrication is optimized for high current density. BLOCK COIL DESIGN STRATEGYWe are developing a new approach to dipole design, in which the coils are configured in rectangular blocks instead of the cos θ geometry used in most superconducting dipoles to date. We are currently building a 16 Tesla dual dipole embodying this approach. We report here the re...

The NbTi model dipole TAMU1 was successfully tested at Lawrence Berkeley Lab. The dipole reached 88% of short-sample current on the first quench, and trained rapidly to 98%. The incorporated quench heaters were capable of inducing a plateau quench in <10 msec. The splice resistance was measured to be 0.28 nΩ in the multi-kA range, indicating an excellent contact. AC loss properties were studied during ramp studies. Ramps to 1,000 A/s (0.9 T/s) operated at greater than 60% plateau current. The dipole is a success. It is significant that this high-field NbTi dipole operated successfully at shortsample current with minimal training, even though the coil was vacuum-impregnated with epoxy. We attribute this performance in part to the stress management that is integrated into the block-coil geometry.