This paper proposes a Higgs factory located in the Tevatron tunnel. It is based on a photon collider by using a recirculating e- linac and fiber laser technology. The design goal is 10,000 Higgs per year.
Because muons connect directly to a standard-model Higgs particle in s-channel production, a muon collider would be an ideal device for precision measurement of the mass and width of a Higgs-like particle, and for further exploration of its productio
n and decay properties. Parameters of a high-precision muon collider are presented and the necessary components and performance are described. An important advantage of the muon collider approach is that the spin precession of the muons will enable energy measurements at extremely high accuracy (dE/E to 10-6 or better). The collider could be a first step toward a high-luminosity multi-TeV lepton collider, and extensions toward a higher-energy higher-luminosity device are also discussed.
Muon acceleration from 30 to 750 GeV in 72 orbits using two rings in the 1000m radius Tevatron tunnel is explored. The first ring ramps at 400 Hz and accelerates muons from 30 to 400 GeV in 28 orbits using 14 GV of 1.3 GHz superconducting RF. The rin
g duplicates the Fermilab 400 GeV main ring FODO lattice, which had a 61m cell length. Muon survival is 80%. The second ring accelerates muons from 400 to 750 GeV in 44 orbits using 8 GV of 1.3 GHz superconducting RF. The 30 T/m main ring quadrupoles are lengthened 87% to 3.3m. The four main ring dipoles in each half cell are replaced by three dipoles which ramp at 550 Hz from -1.8T to +1.8T interleaved with two 8T fixed superconducting dipoles. The ramping and superconducting dipoles oppose each other at 400 GeV and act in unison at 750 GeV. Muon survival is 92%. Two mm copper wire, 0.28mm grain oriented silicon steel laminations, and a low duty cycle mitigate eddy current losses. Low emittance muon bunches allow small aperatures and permit magnets to ramp with a few thousand volts. Little civil construction is required. The tunnel exists.
Recent discovery of a Higgs boson boosted interest in a low-energy medium-luminosity Muon Collider as a Higgs Factory (HF). A preliminary design of the HF storage ring (SR) is based on cos-theta Nb3Sn superconducting (SC) magnets with the coil inner
diameter ranging from 50 cm in the interaction region to 16 cm in the arc. The coil cross-sections were chosen based on the operation margin, field quality and quench protection considerations to provide an adequate space for the beam pipe, helium channel and inner absorber (liner). With the 62.5-GeV muon energy and 2 x 10^12 muons per bunch, the electrons from muon decays deposit about 300 kW in the SC magnets, or unprecedented 1 kW/m dynamic heat load, which corresponds to a multi-MW room temperature equivalent. Based on the detailed MARS15 model built and intense simulations, a sophisticated protection system was designed for the entire SR to bring the peak power density in the SC coils safely below the quench limit and reduce the dynamic heat load to the cold mass by a factor of 100. The system consists of tight tungsten masks in the magnet interconnect regions and elliptical tungsten liners optimized for each magnet.
A low-energy Muon Collider (MC) offers unique opportunities to study the recently found Higgs boson. However, due to a relatively large beam emittance with moderate cooling in this machine, large-aperture high- field superconducting (SC) magnets are
required. The magnets need also an adequate margin to operate at a large radiation load from the muon decay showers. General specifications of the SC dipoles and quadrupoles for the 125 GeV c.o.m. Higgs Factory with an average luminosity of ~2x10**31 cm-2s-1 are formulated. Magnet conceptual designs and parameters are reported. The impact of the magnet fringe fields on the beam dynamics as well as the IR and lattice magnet protection from radiation are also reported and discussed.
Plasma wakefield acceleration (PWFA) holds much promise for advancing the energy frontier because it can potentially provide a 1000-fold or more increase in acceleration gradient with excellent power efficiency in respect with standard technologies.
Most of the advances in beam-driven plasma wakefield acceleration were obtained by a UCLA/USC/SLAC collaboration working at the SLAC FFTB[ ]. These experiments have shown that plasmas can accelerate and focus both electron and positron high energy beams, and an accelerating gradient in excess of 50 GeV/m can be sustained in an 85 cm-long plasma. The FFTB experiments were essentially proof-of-principle experiments that showed the great potential of plasma accelerators. The FACET[ ] test facility at SLAC will in the period 2012-2016 further study several issues that are directly related to the applicability of PWFA to a high-energy collider, in particular two-beam acceleration where the witness beam experiences high beam loading (required for high efficiency), small energy spread and small emittance dilution (required to achieve luminosity). The PWFA-LC concept presented in this document is an attempt to find the best design that takes advantage of the PWFA, identify the critical parameters to be achieved and eventually the necessary R&D to address their feasibility. It best benefits from the extensive R&D that has been performed for conventional rf linear colliders during the last twenty years, especially ILC[ ] and CLIC[ ], with a potential for a comparably lower power consumption and cost.