Magnets for the Very Large Hadron Collider

Early in 1998, a steering committee was set up in the U.S. to look at a proton-proton collider with center of mass energy signi cantly above that of the LHC. The steering committee was set up in response to one of the recommendations of the 1997-1998 HEPAP Subpanel report on the future of U.S. High Energy Physics. The steering committee chose a temporary name for the machine, very large hadron collider (vlhc), a nominal set of machine parameters (from Snowmass '96) and appointed working groups on accelerator physics, magnets technologies, and accelerator systems. Each working group was asked to hold at least one workshop per year and to make an annual report to the steering committee. This note summarizes the rst workshop on magnet technologies, held in Port Je erson, NY, last November. The available talks can be accessed via the BNL magnet group Web site (http://magnets.rhic.bnl.gov) or via the vlhc Web site (http://vlhc.org). The vlhc Web site also has links to the proceedings of the other two workshops, which were held in February, and information about the annual vlhc meeting (June 28-30 in Monterey, California). The working group on magnet technologies was asked to focus on innovative concepts that would result in signi cant cost reductions. Activities are to be coordinated with other working groups and include encouraging progress in superconducting materials. Work on new types of magnets, some with new types of superconductors, is underway at BNL, Cornell, Fermilab, LBNL, and Texas A and M. This work was discussed in detail at the workshop. Overview talks on the Snowmass '96 parameters, accelerator physics, and superconductors provided a framework for the magnet activity. The pp colliders studied at the DPF Snowmass '96 workshop had center of mass energy 100 Gev and luminosity 10cm sec . Three colliders, characterized by di ering magnetic elds, were studied. One collider was based on a dipole magnetic eld of 12.5 T. Such a machine would have a circumference of 100 km and a synchrotron radiation damping time for the beam emittance of 1.3 hours. Since the familiar NbTi superconductor has a critical eld of 10 T, magnets for such a machine would require a new type of superconductor, such as Nb3Sn or high temperature superconductor (HTS). The second collider was based on the use of NbTi to achieve a dipole eld approaching 10 T. None of the work reported at the magnet workshop was based on this type of magnet. The third collider was based on a low eld ( 2T ), iron-dominated magnet. Such a machine would have nominal circumference 550 km and no synchrotron damping.