Last two years were very important in history of a photon colliders. This option is included now in conceptual design reports of the NLC, JLC and TESLA/SBLC projects. All the designs foresee two interaction regions: one for e+e- and the second for gamma-gamma, gamma-e and e^-e^- collisions. This paper is focused on three aspects: 1) arguments for photon colliders; 2) parameters of current projects; 3) ultimate luminosities and energies, new ideas. Recent studies have shown that the main collision effect - coherent pair creation - is suppressed at photon colliders with the energy (2E < 2 TeV) due to the beam repulsion, and one can achieve, in principle, the gamma-gamma luminosity exceeding 10^{35} cm^-2s^-1. The required electron beams with very small emittances can be obtained, for example, using a laser cooling of electron beams. This new method requires a laser with a power by one order of magnitude higher than that required for the ``conversion'' of electrons to photons. Such lasers are not available today, but hopefully they will appear by the time when linear colliders will be built. High energy gamma-gamma, gamma-e colliders with the luminosity comparable to that in e^+e^- collisions are beyond the competition in study of many phenomena of particle physics.
The discovery of the Higgs boson (and still nothing else) have triggered appearance of many proposals of Higgs factories for precision measurement of the Higgs properties. Among them there are several projects of photon colliders (PC) without e+e- in addition to PLC based on e+e- linear colliders ILC and CLIC. In this paper, following a brief discussion of Higgs factories physics program I give an overview of photon colliders based on linear colliders ILC and CLIC, and of the recently proposed photon-collider Higgs factories with no e+e- collision option based on recirculation linacs in ring t…
Using the laser backscattering method at future TeV linear colliders one can obtain gamma-gamma and electron-gamma colliding beams (photon colliders) with the energy and luminosity comparable to that in e+e- collisions. Now this option is included to conceptual designs of linear colliders. This paper (talk at the conference on nonlinear optics) is a short introduction to this field with an emphasis on required lasers which can be used both for e -> gamma conversion and for preparation of electron beams (photoguns, laser cooling), some interesting nonlinear QED effects in a strong field which a…
High energy photon - photon collisions can be achieved by adding high average power short-pulse lasers to the Linear Collider, enabling an expanded physics program for the facility. The technology required to realize a photon linear collider continues to mature. Compton back-scattering technology is being developed around the world for low energy light source applications and high average power lasers are being developed for Inertial Confinement Fusion.
For more than 30 years [1], gamma-gamma and gamma-electron photon colliders have been considered a natural addition to e+e- linear-collider projects. Following the recent discovery of the Higgs boson, the physics community has been actively considering various approaches to building a Higgs factory, a photon collider (with or without e+e-) being one of them. In this note, following a brief discuss of photon colliders based on ILC and CLIC, I give a critical overview of the recently proposed photon-collider Higgs factories with no e+e- collision option.
Muon-based accelerators have the potential to enable facilities at both the Intensity and the Energy Frontiers. Muon storage rings can serve as high precision neutrino sources, and a muon collider is an ideal technology for a TeV or multi-TeV collider. Progress in muon accelerator designs has advanced steadily in recent years. In regard to 6D muon cooling, detailed and realistic designs now exist that provide more than 5 order-of-magnitude emittance reduction. Furthermore, detector performance studies indicate that with suitable pixelation and timing resolution, backgrounds in the collider det…
We in the physics community expect the LHC to uncover new physics in the next few years. The character and energy scale of the new physics remain unclear, but it is likely that data from the LHC will need to be complemented by information from a lepton collider which can provide for precise examination of new phenomena. We describe the concept, accelerator design, and detector R&D for a high energy Muon Collider as well as the challenges associated with the machine and its detector environment.
Photon collider based on cold and warm linear collider technologies are compared from the point of view of attainable luminosities, technical feasibility of laser systems and experimental conditions.
In this conference paper, I review the present status and technical problems of the Photon collider, as well as various additional applications of Compton scattering.
High energy photon colliders based on laser backscattering are a very natural extension of a e+e- linear colliders and open new possibilities to study of the matter. This option has been included in the pre-conceptual designs of linear colliders and work on Technical Design Reports is in progress. The physics motivation for photon colliders is quite clear though more studies are needed. The proof of its technical feasibility and the search for the best solutions is of first priority now. In this talk we discuss: physics motivation, laser problems and new possible solutions, and generation of l…
Linear colliders offer a unique possibility to study gamma gamma and gamma electron interactions at the energies 0.1--2 TeV. This option is now included in design reports of NLC, JLC and TESLA/SBLC. This paper includes: status of photon colliders, new possibilities in study of Higgs boson, ways to achieve high luminosities.
Using the laser backscattering method at future linear colliders one can obtain gamma-gamma and gamma-electron colliding beams (photon colliders) with energy and luminosity comparable to that in e^+e^- collisions. This option has been included in the pre-conceptual designs of linear colliders and in work on a Technical Design Report which is in progress. The physics motivation for photon colliders is quite clear. The proof of its technical feasibility and the search for the best solutions is of first priority now. A key element of a photon collider is a laser with high peak power and repetitio…
In this invited talk at the ``historical'' session of PHOTON2005, I was asked to recount the history and the development, from its earliest days to the present, of the idea of photon colliders based on conversion of high energy electrons to high-energy photons at a future high-energy linear e+e- collider. Described in this talk are the general features and schemes of a photon collider, the evolution in understanding of what the parameters of a realistic photon collider are, possible solutions of various technical problems, the physics motivation, and the present status of photon-collider devel…
The investigation of lepton-hadron and photon-hadron collisions at TeV scale is crucial both to clarify the strong interaction dynamics from nuclei to quark-parton level and for adequate interpretation of experimental data from future hadron colliders (LHC and VLHC). In this presentation different TeV scale lepton-hadron and photon-hadron collider proposals (such as THERA, LEP-LHC, QCD Explorer etc) are discussed. The advantages of linac-ring type colliders has been shown comparatively.
The advantage of the linac-ring type electron proton collider is that it allows for the straightforward construction of $γ$p collider. In a $γ$p collider high energy photons can be generated from Compton backscattering of laser photons off electrons from a linear accelerator. In this study main parameters of photon-proton colliders based on some future electron linear accelerator projects and protons supplied form LHC or FCC are evaluated.
The status and initial performance of a simulation program CAIN for interaction region of linear colliders is described. The program is developed to be applicable for e+e-, e-e-, e-gamma and gamma-gamma linear colliders. As an example of an application, simulation of a gamma-gamma collider option of NLC is reported.
Methods of gamma-gamma, gamma-electron luminosities measurement at photon colliders based on Compton scattering of laser photons on high energy electrons at linear colliders are considered.
New facilities for particle and nuclear physics research, which will be available due to constructing the TESLA linear electron-positron collider tangentially to the HERA proton ring, are discussed.
Photon beams at photon colliders are very narrow, powerful (10--15 MW) and cannot be spread by fast magnets (because photons are neutral). No material can withstand such energy density. For the ILC-based photon collider, we suggest using a 150 m long, pressurized (P ~ 4 atm) argon gas target in front of a water absorber which solves the overheating and mechanical stress problems. The neutron background at the interaction point is estimated and additionally suppressed using a 20 m long hydrogen gas target in front of the argon.
Options for future $lepton-proton,lepton-nucleus,γ-proton,γ-nucleus$ and FEL$γ-nucleus$ colliders are discussed. In the spirit of this content, we consider TESLAxHERA, LEPxLHC, $μ$xTEVATRON, exRHIC, LinacxLHC, $\sqrt{s}=3TeV$ $μp$ and CLIC based colliders.
Construction of future electron-positron colliders (or dedicated electron linac) and muon colliders (or dedicated muon ring) tangential to Future Circular Collider (FCC) will give opportunity to utilize highest energy proton and nucleus beams for lepton-hadron and photon-hadron collisions. Luminosity values of FCC based ep, \mup, eA, \muA, \gammap and \gammaA colliders are estimated. Multi-TeV center of mass energy ep colliders based on the FCC and linear colliders (LC) are considered in detail. Parameters of upgraded versions of the FCC proton beam are determined to optimize luminosity of ele…
A photon collider luminosity and its energy are determined by the parameters of an electron-electron linear collider (energy, power, beam emittances) and collision effects. The main collision effect is the coherent e+e- pair creation. At low energies (2E < 0.5 - 1 TeV) this process is suppressed due to repulsion of electron beams. In this region gamma-gamma luminosity above 10^{35} cm-2 s-1 is possible (10^{33} is sufficient). At higher energies the limited average beam power and coherent pair creation restrict the maximum energy of photon colliders (with sufficient luminosity) at 2E ~ 5 TeV. …
The construction of the ILC tangential to Tevatron ring will give opportunity to investigate electron-proton, positron-proton, electron-antiproton, positron-antiproton interactions at 1 TeV center of mass energy. The analysis of the lepton-hadron collisions in these energy region is very important both for understanding of strong interaction dynamics and for adequate interpretation of future LHC and VLHC data. In addition, ILC-Tevatron collider will provide a possibility to realize photon-hadron collisions in the same energy region using Compton backscattered laser photon off ILC electron beam…
This paper is the second part of my overview on photon colliders given at the conference ``The photon: its first hundred years and the future'' (PHOTON2005 + PLC2005). The first paper describes the first 25 years of the history and evolution of photon colliders. The present paper considers the photon collider at the ILC: possible parameters, technical problems and present status.
In this brief overview we will reflect on the process of the design of the linear collider (LC) final focus (FF) optics, and will also describe the theoretical and experimental efforts on design and practical realisation of a prototype of the LC FF optics implemented in the ATF2 facility at KEK, Japan, presently being commissioned and operated.
The purpose of this Introduction, presented at PHOTON2007, is to provide an overview of the basic principles, possible parameters, some technical aspects and the physics program of the photon collider and discuss its status within the ILC project.
Besides continued work on the parameters of a 3-4 and 0.5 TeV CoM collider, many studies are now concentrating on a machine near 100 GeV that could be a factory for the s-channel production of Higgs particles. We mention the research on the various components in such muon colliders, starting from the proton accelerator needed to generate pions from a heavy-Z target and proceeding through the phase rotation and decay channel, muon cooling, acceleration, storage in a ring and the collider detector. We also mention theoretical and experimental R&D plans for the next several years that should lead…
One of the interaction regions at the linear colliders should be compatible both with e+e- and gamma-gamma, gamma-electron modes of operation. In this paper, the differences in requirements and possible design solutions are discussed.
At linear colliders, the e+e- luminosity is limited by beam-collision effects, which determine the required emittances of beams in damping rings (DRs). While in gamma-gamma collisions at the photon collider, these effects are absent, and so smaller emittances are desirable. In present damping rings designs, nominal DR parameters correspond to those required for e+e- collisions. In this note, I would like to stress once again that as soon as we plan the photon-collider mode of ILC operation, the damping-ring emittances are dictated by the photon-collider requirements--namely, they should be as …
