Bruce J. King

Target studies with BNL E951 at the AGS

We report initial results of exposing low-Z solid and high-Z liquid targets to 150-ns, 4/spl times/10/sup 12/ proton pulses with spot sizes on the order of 1 to 2 mm. The energy deposition density approached 100 J/g. Diagnostics included fiberoptic strain sensors on the solid target and high-speed photography of the liquid targets. This work is part of the R&D program of the Neutrino Factory and Muon Collider Collaboration.

Neutrino physics at a muon collider

An overview is given of the neutrino physics potential of future muon storage rings that use muon collider technology to produce, accelerate and store large currents of muons.

An R&D program for targetry and capture at a neutrino factory and muon collider source

The need for intense muon beams for muon colliders and for neutrino factories based on muon storage rings leads to a concept of 1-4 MW proton beams incident on a moving target that is inside a 20-T solenoid magnet, with a mercury jet as a preferred example. Novel technical issues for such a system include disruption of the mercury jet by the proton beam and distortion of the jet on entering the solenoid, as well as more conventional issues of materials lifetime and handling of activated materials in an intense radiation environment. As part of the R&D program of the Neutrino Factory and Muon Collider Collaboration, an R&D eort related to

Potential hazards from neutrino radiation at muon colliders

High energy muon colliders, such as the TeV-scale conceptual designs now being considered, are found to produce enough high energy neutrinos to constitute a potentially serious off-site radiation hazard in the neighbourhood of the accelerator site. A general characterization of this radiation hazard is given, followed by an order-of-magnitude calculation for the off-site annual radiation dose and a discussion of accelerator design and site selection strategies to minimize the radiation hazard.

A cupronickel rotating band pion production target for muon colliders

A conceptual design is presented for a high power cupronickel pion production target. It forms a circular band in a horizontal plane with approximate dimensions of: 2.5 meters radius, 6 cm high and 0.6 cm thick. The target is continuously rotated at 3 m/s to carry heat away from the production region to a water cooling channel. Bunches of 16 GeV protons with total energies of 270 kJ and repetition rates of 15 Hz are incident tangentially to are of the target along the symmetry axis of a 20 Tesla solenoidal magnetic capture channel. The mechanical layout and cooling setup are described. Results are presented from realistic MARS Monte Carlo computer simulations of the pion yield and energy deposition in the target. ANSYS finite element calculations are beginning to give predictions for the resultant shock heating stresses.

High rate neutrino detectors for neutrino factories

Abstract Three types of high-rate neutrino detectors for neutrino interaction physics at neutrino factories are discussed. High-performance general-purpose detectors might collect event samples of the order of a billion events or more. This could greatly improve on the existing analyses of neutrino interactions and also lead to new and important analysis topics including, for example, precise determinations of the CKM matrix elements | V ub | and | V cb |. The potential of such general-purpose detectors is illustrated with reference to a previously discussed detector (B.J. King, Neutrino physics at a Muon Colliders, Proceedings of the Workshop on Physics at the First Muon Collider and Front End of a Muon Collider, Fermilab, November 6–9, 1997) that is structured around a novel and compact vertexing and tracking neutrino target comprising a stack of CCD pixel devices. Design ideas and prospects are also discussed for two types of specialized detectors: (i) polarized targets filled with polarized solid protium–deuterium (HD), for unique and powerful studies of the nucleons spin structure, and (ii) fully active liquid tracking targets with masses of several tonnes for precise determinations of the weak mixing angle, sin 2 θ W , from the total cross-section for neutrino–electron scattering. All three detector types pose severe technical challenges but their utilization could add significantly to the physics motivation for neutrino factories.

Muon Colliders: New Prospects for Precision Physics and the High Energy Frontier

An overview is given of muon collider technology and of the current status of the muon collider research program. The exciting potential of muon colliders for both neutrino physics and collider physics studies is then described and illustrated using self-consistent collider parameter sets at 0.1 TeV to 100 TeV center-of-mass energies.

Neutrino radiation challenges and proposed solutions for many-TeV muon colliders

Neutrino radiation is expected to impose major design and siting constraints on many-TeV muon colliders. Previous predictions for radiation doses at TeV energy scales are briefly reviewed and then modified for extension to the many-TeV energy regime. The energy-cubed dependence of lower energy colliders is found to soften to an increase of slightly less than quadratic when averaged over the plane of the collider ring and slightly less than linear for the radiation hot spots downstream from straight sections in the collider ring. Despite this, the numerical values are judged to be sufficiently high that any many-TeV muon colliders will likely be constructed on large isolated sites specifically chosen to minimize or eliminate human exposure to the neutrino radiation. It is pointed out that such sites would be of an appropriate size scale to also house future proton-proton and electron-positron colliders at the high energy frontier, which naturally leads to conjecture on the possibilities for a new world laboratory for high energy physics. Radiation dose predictions are also presented for the speculative possibility of linear muon colliders. These have greatly reduced radiation constraints relative to circular muon colliders because radiation is only emitted in two pencil beams directed along the axes of the opposing linacs.

Rotating band pion production targets for muon colliders and neutrino factories

Abstract An update is presented on a conceptual design for a pion production target station using a rotating cupronickel band and that was originally proposed for use at a muon collider facility with a 4 MW pulsed proton beam. After reviewing the salient design features and motivations for this target, ongoing studies are described that are attempting to benchmark the thermal stresses and radiation damage on the target band using data from the Fermilab antiproton source and other operating targets. Possible parameter optimizations and alternative technologies for the rotating band are surveyed, including discussion on the the various proton beam parameters that might be encountered for rotating band targets at either muon colliders or neutrino factories. Finally, an outline is proposed for a possible R&D path towards capability for the actual construction of rotating band pion production targets.

Neutrino physics at muon colliders

An overview is given of the neutrino physics potential of future muon storage rings that use muon collider technology to produce, accelerate and store large currents of muons.