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Design of the muon collider lattice: Present status

Description: The last component of a muon collider facility, as presently envisioned, is a colliding-beam storage ring. Design studies on various problems for this ring have been in progress over the past year. In this paper we discuss the current status of the design. The projected muon currents require very low beta values at the IP, {beta}* = 3 mm, in order to achieve the design luminosity of L = 10{sup 35} cm{sup -2} s{sup -1}. The beta values in the final-focus quadrupoles are roughly 400 km. To cancel the corresponding chromaticities, sextupole schemes for local correction have been included in the optics of the experimental insertion. The hour-glass effect constraints the bunch length to be comparable too. To obtain such short bunches with reasonable rf voltage requires a very small value of the momentum compaction a, which can be obtained by using flexible momentum compaction (FMC) modules in the arcs. A preliminary design of a complete collider ring has now been made; it uses an experimental insertion and arc modules as well as a utility insertion. The layout of this ring is shown schematically, and its parameters are summarized. Though some engineering features are unrealistic, and the beam performance needs some improvement, we believe that this study can serve as the basis for a workable collider design. The remaining sections of the paper will describe the lattice, show beam behaviour, and discuss future design studies.
Date: May 1996
Creator: Garren, A.; Courant, E. & Gallardo, J.
Partner: UNT Libraries Government Documents Department

A proton driver for the muon collider source with a tunable momentum compaction lattice

Description: The future Muon Collider will have a luminosity of the order of 10{sup 35} cm{sup {minus}2{minus}1} during 1,000 turns when the muons decay. This requires 10{sup 12} muons per bunch. The muon source is a 30 GeV proton driver with 2.5 10{sup 13} protons per pulse. The proton bunch length should be of the order of 1 ns. Short bunches could be created by a tunable momentum compaction lattice which would bring the momentum compaction to zero in a short time. This isochronous conduction would allow bunches to shear and become very short in time. The authors present a lattice where the momentum compaction is a tunable parameter at fixed horizontal and vertical betatron tunes. The values of the maxima of the dispersion function are kept small. They examine two kinds of lattices, with combined function as well as normal dipole and quadrupole magnets.
Date: July 1, 1997
Creator: Trbojevic, D.; Brennan, J.M.; Courant, E.D.; Roser, T.; Peggs, S.; Ng, K.Y. et al.
Partner: UNT Libraries Government Documents Department

Coherent synchrotron radiation in the isochronous muon collider ring

Description: To achieve the luminosity of L = 10{sup 35} cm{sup {minus}2}s{sup {minus}1} in a {mu}{sup +}{mu}{sup {minus}} collider, two bunches per sign of N = 2 {times} 10{sup 12} particles each and a betatron function of {beta}* = 3 mm at the interaction point (IP) are required. This small {beta}* at the IP constrains the size of the bunch to be {sigma}{sub z} {approximately} {beta}*. To maintain this rather short bunch without excessive rf power consumption, an isochronous lattice has been chosen for the final collider ring. One of the important advantages of muons as opposed to electrons is that at up to at least TeV energy it is possible to accelerate muons in circular machines as their synchrotron radiation is reduced by a factor of (m{sub e}/m{sub {mu}}){sup 2} {approximately} 23 {times} 10{sup {minus}6} with respect to electrons. Nevertheless, the large number of muons in a short bunch suggests the possibility of strong shielded coherent synchrotron radiation. First, the author uses the well known formulae to evaluate the power of shielded coherent synchrotron radiation in the isochronous muon collider ring. Finally, following the results obtained by Kheifets and Zotter for a bunch with a Gaussian longitudinal charge distribution the author shows that the coherent synchrotron radiation in the isochronous {mu}{sup +}{mu}{sup {minus}} collider ring is negligible if the rms bunch length is larger than {approx} 0.3 mm.
Date: October 1, 1996
Creator: Gallardo, J.C.
Partner: UNT Libraries Government Documents Department

2 x 2 TeV mu(superscript +) mu (superscript) collider

Description: The scenarios for high-luminosity 2 x 2 TeV and 250 x 250 GeV {mu}{sup +}{mu}{sup -} colliders are presented. Having a high physics potential, such a machine has specific physics and technical advantages and disadvantages when compared with an e{sup +}e{sup -} collider. Parameters for the candidate designs and the basic components - proton source, pion production and decay channel, cooling, acceleration and collider storage ring - are considered. Attention is paid to the areas mostly affecting the collider performance: targetry, energy spread, superconducting magnet survival, detector backgrounds, polarization, environmental issues. 13 refs., 9 figs., 4 tabs.
Date: October 1, 1996
Creator: Mokhov, N.V. & Noble, R.J.
Partner: UNT Libraries Government Documents Department

Simulation Studies of Ionization Cooling

Description: A {mu}{sup +}-{mu}{sup -} collider must compress the beam phase-space volume by a factor of {approximately}10{sup 6} to obtain high luminosity, and this beam cooling must occur before {mu}-decay. In this paper we present simulations of ionization cooling which explore the various conditions needed for cooling to collider conditions. Cooling by large factors is demonstrated and directions toward complete cooling scenarios are discussed.
Date: June 1, 1997
Creator: Neuffer, D. & VanGinneken, A.
Partner: UNT Libraries Government Documents Department

RF system concepts for a muon cooling experiment

Description: The feasibility of muon colliders for high energy physics experiments has been under intensive study for the past few years and recent activity has focused on defining an R and D program that would answer the critical issues. An especially critical issue is developing practical means of cooling the phase space of the muons once they have been produced and captured in a solenoidal magnetic transport channel. Concepts for the rf accelerating cavities of a muon cooling experiment are discussed.
Date: June 1998
Creator: Turner, W. C.; Corlett, J. N.; Li, D.; Moretti, A.; Kirk, H. G.; Palmer, R. B. et al.
Partner: UNT Libraries Government Documents Department

Workshop on physics at the first muon collider and front-end of a muon collider: A brief summary

Description: In November 1997 a workshop was held at Fermilab to explore the physics potential of the first muon collider, and the physics potential of the accelerator complex at the `front-end` of the collider. An extensive physics program emerged from the workshop. This paper attempts to summarize this physics program and to identify the main conclusions from the workshop. 14 refs., 1 fig., 5 tabs.
Date: February 1, 1998
Creator: Geer, S.
Partner: UNT Libraries Government Documents Department

Precision measurements at a muon collider

Description: We discuss the potential for making precision measurements of M{sub W} and M{sub T} at a muon collider and the motivations for each measurement. A comparison is made with the precision measurements expected at other facilities. The measurement of the top quark decay width is also discussed.
Date: December 21, 1995
Creator: Dawson, S.
Partner: UNT Libraries Government Documents Department

Comparison of backgrounds in detectors for LHC, NLC and {mu}{sup +}{mu}{sup {minus}} colliders

Description: Background levels in detectors at future high-luminosity colliders of three different types - proton-proton, electron-positron, and muon- antimuon - are analyzed. Two sources - debris from the collision points and those from an accelerator tunnel - are studied. It is shown that hadron, electron and muon colliders are similar and very different at the same time with respect to background origin, integrated radiation levels and instantaneous rates of particles in the detectors. 23 refs., 11 figs., 4 tabs.
Date: March 1, 1996
Creator: Mokhov, N.V.
Partner: UNT Libraries Government Documents Department

High luminosity muon collider design

Description: Muon Colliders have unique technical and physics advantages and disadvantages when compared with both hadron and electron machines. They should be regarded as complementary. Parameters are given of 4 TeV high luminosity {mu}{sup +}{mu}{sup {minus}} collider, and of a 0.5 TeV lower luminosity demonstration machine. We discuss the various systems in such muon colliders.
Date: October 1996
Creator: Palmer, R. & Gallardo, J.
Partner: UNT Libraries Government Documents Department

A practical high-energy high-luminosity {mu}{sup +} {minus} {mu}{sup {minus}} collider

Description: We present a candidate design for a high-energy high-luminosity {mu}{sup +}{minus}{mu} collider, with E{sub cm} = 4 TeV, L = 3 {times} 10{sup 4}cm{sup {minus}2}s{sup {minus}1}, using only existing technology. The design uses a rapid-cycling medium-energy proton synchrotron, which produces proton beam pulses which are focused onto two {pi}-producing targets, with two {pi}-decay transport lines producing {mu}{sup +{prime}}s. The {mu}`s are collected, rf-rotated, cooled and compressed into a recirculating linac for acceleration, and then transferred into a storage ring collider. The keys to high luminosity are maximal {mu} collection and cooling; innovations with these goals are presented, and future plans for collider development are discussed. This example demonstrates a novel high-energy collider type, which will permit exploration of elementary particle physics at energy frontiers beyond the reach of currently existing and proposed electron and hadron colliders.
Date: June 1994
Creator: Palmer, R. B.; Gallardo, J.; Neuffer, D. V. & Gallardo, J.
Partner: UNT Libraries Government Documents Department

High luminosity {mu}{sup +} {mu}{sup {minus}} collider: Report of a feasibility study

Description: Parameters are given of 4 TeV and 0.5 TeV (c-of-m) high luminosity {mu}{sup +}{mu}{sup -} colliders, and of a 0.5 TeV lower luminosity demonstration machine. We discuss the various systems in such muon colliders, starting from the proton accelerator needed to generate the muons and proceeding through muon cooling, acceleration and storage in a collider ring. Detector background, polarization, and nonstandard operating conditions are analyzed. Muon Colliders have unique technical and physics advantages and disadvantages when compared with both hadron and electron machines. They should thus be regarded as complementary. We briefly mention the luminosity requirements of hadrons and lepton machines and their high-energy-physics advantages and disadvantages in reference to their effective center of mass energy. Finally, we present an R & D plan to determine whether such machines are practical.
Date: December 1996
Creator: Palmer, R. B.; Gallardo, J. C.; Tollestrup, A. & Sessler, A.
Partner: UNT Libraries Government Documents Department

Progress on muon{sup +}muon{sup {minus}} colliders

Description: Advantages and disadvantages of muon colliders are discussed. Recent results of calculations of the radiation hazard from muon decay neutrinos are presented. This is a significant problem for machines with center of mass energy of 4 TeV, but of no consequence for lower energies. Plans are outlined for future theoretical and experimental studies. Besides continued work on the parameters of a 4 TeV collider, studies are now starting on a machine near 100 GeV that could be a factory for the s-channel production of Higgs particles. Proposals are also presented for a demonstration of ionization cooling and of the required targeting, pion capture, and phase rotation rf.
Date: May 1, 1997
Creator: Palmer, R. B.
Partner: UNT Libraries Government Documents Department

Design of three recirculating-linac SRF systems for a 4-TeV {mu}{sup +}-{mu}{sup {minus}} collider

Description: In a conceptual design of the accelerating systems for a 4-TeV {mu}{sup +}-{mu}{sup {minus}} collider, three recirculating superconducting linacs (with energies reaching 70 GeV (with 350 MHz SRF), 250 GeV (800 MHz) and 2,000 GeV (1,300 GHz), respectively) are used. The authors briefly describe design concepts for the acceleration features, superconducting RF cavities, input couplers, RF control and RF power systems.
Date: July 1, 1997
Creator: Shu, Q.S.; Neuffer, D. & Simrock, S.
Partner: UNT Libraries Government Documents Department

Higgs resonance studies at the First Muon Collider

Description: Higgs resonance signals and backgrounds at the First Muon Collider are discussed. Effects due to beam polarization and background angular distributions (forward-backward charge asymmetries) are examined. The utility of those features for improving precision measurements and narrow resonance ``discovery`` scans is described.
Date: December 1997
Creator: Kamal, B.; Marciano, W. J. & Parsa, Z.
Partner: UNT Libraries Government Documents Department

A lattice for the 50 GeV muon collider ring

Description: A recent progress report on the lattice design of the 50-50 GeV muon collider is presented. The ring circumference needs to be as small as possible due to the short lifetime of the 50 GeV muons. The background at the detector is affected by the continuous decay of muons into electrons which requires a dipole between the high focusing quadrupoles and the detector. To obtain a luminosity on the order of 1{times}10{sup 33} cm{sup {minus}2} s{sup {minus}1} it is required to have beam intensities on the order of 1{times}10{sup 12} particles per bunch. The rms momentum spread of the beam is equal to 0.12% and the beta functions at the interaction point are equal to 4 cm. The maxima of the betatron functions at these quadrupoles are 1,300 m, resulting in large chromaticities which must be corrected by local chromatic correction. Pairs of horizontal and vertical chromatic sextupoles are located at locations where the corresponding betatron functions are 100 m and the values of the horizontal dispersion functions are 3 and 2 m, respectively. They are carefully placed so that most of their nonlinear effects are canceled. The dynamic aperture is larger than 7 times the mean size of the beam for the momentum offsets larger than {minus}6 and +10 sigmas.
Date: August 1, 1998
Creator: Trbojevic, D.; Ng, K.Y. & Weishi, W.
Partner: UNT Libraries Government Documents Department

Status report of a high luminosity muon collider and future research and development plans

Description: Muon Colliders have unique technical and physics advantages and disadvantages when compared with both hadron and electron machines. They should thus be regarded as complementary. Parameters are given of 4 TeV and 0.5 TeV (c-of-m) high luminosity {mu}{sup +}{mu}{sup -} colliders, and of a 0.5 TeV lower luminosity demonstration machine. We discuss the various systems in such muon colliders, starting from the proton accelerator needed to generate the muons and proceeding through muon cooling, acceleration and storage in a collider ring. Detector background, polarization, and nonstandard operating conditions are analyzed. Finally, we present an R & D plan to determine whether such machines are practical, and, if they are, lead to the construction of a 0.5 TeV demonstration by 2010, and to a 4 TeV collider by the year 2020.
Date: November 1996
Creator: Palmer, R. B.; Tollestrup, A. & Sessler, A.
Partner: UNT Libraries Government Documents Department

R-parity violation and sneutrino resonances at muon colliders

Description: In supersymmetric models with R-parity violation, sneutrinos may be produced as channel resonances at {mu}{sup +}{mu}{sup {minus}} colliders. The authors demonstrate that, for R-parity violating couplings as low as 10{sup {minus}4}, sneutrino resonances may be observed and may be exploited to yield high precision SUSY parameter measurements. The excellent beam energy resolution of muon colliders may also be used to resolve MeV level splitting between CP-even and CP-odd sneutrino mass eigenstates.
Date: January 1, 1998
Creator: Feng, J.L.
Partner: UNT Libraries Government Documents Department

Top polarization at a {mu}{sup +} {mu}{sup {minus}} collider

Description: The top quark pairs produced at a polarized muon collider are in a (nearly) pure spin configuration. This result holds for all center-of-mass energies, and is insensitive to the next-to-leading order QCD radiative corrections. The decay products of a polarized top quark show strong angular correlations. The authors describe an interesting interference effect between the left-handed and longitudinally polarized W bosons in top quark decay. This effect is easily observable in the angular distribution of the charged lepton with respect to the beam axis.
Date: January 27, 2000
Creator: Parke, S. & Mahlon, G.
Partner: UNT Libraries Government Documents Department

New high intensity muon sources and flavor changing neutral currents

Description: There is a great deal of interest in high-intensity muon beams and their use in high Luminosity muon colliders, rare interactions and decays of muons. The authors briefly discuss the need for very intense muon sources to reach the required luminosities for the high energy muon colliders; the theoretical interest to explore lepton flavor violating muon processes; and some ideas for making substantial improvements in the sensitivity of experiments to study Flavor changing neutral currents.
Date: June 1, 1997
Creator: Parsa, Z.
Partner: UNT Libraries Government Documents Department

DIS prospects at the future muon collider facility

Description: We discuss prospects of deep inelastic scattering physics capabilities at the future muon collider facility. In addition to {mu}{sup +}{mu}{sup -} collider itself, the facility provides other possibilities. Among the possibilities, we present muon-proton collider and neutrino fixed target programs at the muon collider facility. This {mu}-p collider program extends kinematic reach and luminosity by an order of magnitude, increasing the possibility of search for new exotic particles. Perhaps most intriguing DIS prospects come from utilizing high intensity neutrino beam resulting from continuous decays of muons in various sections of the muon collider facility. One of the most interesting findings is a precision measurement of electroweak mixing angle, sin{sup 2}{theta}{sub W}, which can be achieved to the precision equivalent to {delta}M{sub W}{approximately} 30MeV.
Date: July 1, 1998
Creator: Yu, J., FERMI
Partner: UNT Libraries Government Documents Department

Beam dynamics problems for a {mu}{sup +}-{mu}{sup -} collider

Description: A {mu}{sup +}-{mu}{sup -} collider requires a high-intensity proton source for {pi}-production, a high-acceptance {pi}-{mu} decay channel, a {mu}-cooling system, a rapid acceleration system, and a high-luminosity collider ring for the collision of short, intense {mu}{sup +}-{mu}{sup -} bunches. Significant beam-dynamics problems exist in each of these systems. These problems and some paths to solutions are discussed in this paper.
Date: June 1, 1997
Creator: Neuffer, D.
Partner: UNT Libraries Government Documents Department

Nb{sub 3}Sn magnets for a muon collider

Description: High field dipole and quadrupole magnet designs with racetrack coils are investigated. The design option is particularly attractive for a muon collider dipole magnet using the Nb{sub 3}Sn superconductor. A conceptual design of {approximately}15 T single aperture dipole magnet is presented where the coils maintain a simple 2-d structure through the ends. The use of racetrack coils in quadrupole magnets is also discussed. It appears that the racetrack coils are less attractive for high gradient quadrupole magnets.
Date: July 1998
Creator: Gupta, R. C.; Green, M. A.; Scanlan, R. M. & Palmer, R.
Partner: UNT Libraries Government Documents Department