Particle acceleration in plasma creates a possibility of exceptionally high accelerating gradients and appears as a very attractive option for future linear electron-positron and/or photon-photon colliders. These high accelerating gradients were already demonstrated in a number of experiments. However, a linear collider requires exceptionally high beam brightness which still needs to be demonstrated. In this article we discuss major phenomena which limit the beam brightness of accelerated beam and, consequently, the collider luminosity.
Recent simulation shows that a self-modulated high energy proton bunch can excite a large amplitude plasma wakefield and accelerate an externally injected electron bunch to the energy frontier in a single stage acceleration through a long plasma channel. Based on this scheme, future colliders, either an electron-positron linear collider (e+-e- collider) or an electron-hadron collider (e-p collider) can be conceived. In this paper, we discuss some key design issues for an e+-e- collider and a high energy e-p collider, based on the existing infrastructure of the CERN accelerator complex.
Recent simulations have shown that a high-energy proton bunch can excite strong plasma wakefields and accelerate a bunch of electrons to the energy frontier in a single stage of acceleration. It therefore paves the way towards a compact future collider design using the proton beams from existing high-energy proton machines, e.g. Tevatron or the LHC. This paper addresses some key issues in designing a compact electron-positron linear collider and an electron-proton collider based on existing CERN accelerator infrastructure.
This note outline the formulae of luminosity and beam-beam tune shifts applicable to flat-beam asymmetric colliders. The formulae are tested with the machine parameters of SuperKEKB.
We calculate the geometric luminosity loss caused by filamentation of transverse kicks, upright and skew quadrupolar errors due to discharges, so-called RF-breakdown, in the acceleration structures of a Linear Collider.
Northern Illinois University（北伊利诺伊大学）；Arizona State University（亚利桑那州立大学）；Thomas Jefferson National Accelerator facility（托马斯·杰斐逊国家加速器设施）；Karlsruhe Institute of Technology（卡尔斯鲁厄理工学院）
Muon Colliders have unique technical and physics advantages and disadvantages when compared with both hadrons and electron machines. They should be regarded as complementary. Parameters are given of a 4 TeV high luminosity muon-muon collider, and of a 0.5 TeV demonstration machine. We discuss the various systems in such muon collider.
Alternative acceleration technologies are currently under development for cost-effective, robust, compact and efficient solutions. One such technology is plasma wakefield acceleration, driven by either a charged particle or laser beam. However, the potential issues must be studied in detail. In this paper, the emittance growth of the witness beam through elastic scattering from gaseous media is derived. The model is compared with the numerical studies.
A high luminosity energy recovery linac on ring type electron-positron collider operating as super charm factory is proposed. It is shown that the luminosity L=2.3 10^35 cm^-2s^-1 can be achieved for center of mass energy 3.77 GeV. The physics goals of this machine in investigation for charmed particles properties are briefly discussed.
The design luminosity for the future linear colliders is very demanding and challenging. Beam-based feedback systems will be required to achieve the necessary beam-beam stability and steer the two beams into collision. In particular we have studied the luminosity performance improvement by intra-train beam-based feedback systems for position and angle corrections at the interaction point. We have set up a simulation model which introduces different machine imperfections and can be applied to both the International Linear Collider (ILC) and the Compact Linear Collider (CLIC).
The Compact Linear Collider is one of the two main European options for a collider in a post Large Hadron Collider era. This is a linear $e^+e^-$ collider with three centre-of-mass energy stages: 380 GeV, 1.5 TeV and 3 TeV. The luminosity performance of the first stage at 380 GeV is presented including the impact of static and dynamic imperfections. These calculations are performed with fully realistic tracking simulations from the exit of the damping rings to the interaction point and including beam-beam effects in the collisions. A luminosity of $4.3\times10^{34}\,\text{cm}^{-2}\text{s}^{-1}…
A formula for the collider luminosity is derived for a head-on collision of two beams with different parameters. Three particular cases are presented: the collision of two identical axially symmetric bunches, the collision of a bunch with a coasting beam, and the collision of two coasting beams. The colliding beams have coinciding longitudinal axes. The formula is valid for colliding both counter propagating and co-propagating ("merging") beams.
A good understanding of the luminosity performance in a collider, as well as reliable tools to analyse, predict, and optimise the performance, are of great importance for the successful planning and execution of future runs. In this article, we present two different models for the evolution of the beam parameters and the luminosity in heavy-ion colliders. The first, Collider Time Evolution (CTE) is a particle tracking code, while the second, the Multi-Bunch Simulation (MBS), is based on the numerical solution of ordinary differential equations for beam parameters. As a benchmark, we compare si…
The robust conjugate direction search (RCDS) method has high tolerance to noise in beam experiments. It has been demonstrated that this method can be used to optimize the machine performance of a light source online. In our study, taking BEPCII as an example, the feasibility of online tuning of the luminosity in a circular collider is explored, through numerical simulation and preliminary online experiments. It is shown that the luminosity that is artificially decreased by a deviation of beam orbital offset from optimal trajectory can be recovered with this method.
In high energy physics, the luminosity is one useful value to characterize the performance of a particle collider. To gain more available data, we need to maximize the luminosity in most collider experiments. With the discussions of tune shift involved the beam dynamics and a recently proposed "crabbed waist" scheme of beam-beam collisions, we present some qualitative analysis to increase the luminosity. In addition, beam-beam tune shifts and luminosities of $e^{+}e^{-}$, $pp$/$p\bar{p}$, and $μ^{+}μ^{-}$ colliders are discussed.
In this paper, we describe a future electron-ion collider (EIC), based on the existing Relativistic Heavy Ion Collider (RHIC) hadron facility, with two intersecting superconducting rings, each 3.8 km in circumference. A new ERL accelerator, which provide 5-30 GeV electron beam, will ensure 10^33 to 10^34 cm^-2 s^-1 level luminosity.
A high-energy muon collider scenario requires a final cooling system that reduces transverse emittance to ~25 microns (normalized) while allowing longitudinal emittance increase. Ionization cooling using high-field solenoids (or Li Lens) can reduce transverse emittances to ~100 microns in readily achievable configurations, confirmed by simulation. Passing these muon beams at ~100 MeV/c through cm-sized diamond wedges can reduce transverse emittances to ~25 microns, while increasing longitudinal emittances by a factor of ~25. Implementation will require optical matching of the exiting beam into…
A detailed model of the High Luminosity LHC inner triplet region with new large-aperture Nb3Sn magnets, field maps, corrector packages, and segmented tungsten inner absorbers was built and implemented into the FLUKA and MARS15 codes. In the optimized configuration, the peak power density averaged over the magnet inner cable width is safely below the quench limit. For the integrated luminosity of 3000 fb-1, the peak dose in the innermost magnet insulator ranges from 20 to 35 MGy. Dynamic heat loads to the triplet magnet cold mass are calculated to evaluate the cryogenic capability. In general, …
A high-energy muon collider scenario require a "final cooling" system that reduces transverse emittance by a factor of ~10 while allowing longitudinal emittance increase. The baseline approach has low-energy transverse cooling within high-field solenoids, with strong longitudinal heating. This approach and its recent simulation are discussed. Alternative approaches which more explicitly include emittance exchange are also presented. Round-to-flat beam transform, transverse slicing, and longitudinal bunch coalescence are possible components of an alternative approach. Wedge-based emittance exch…
We present results from luminosity, energy and polarization studies at a future Linear Collider. We compare e+e- and e-e- modes of operation and consider both NLC and TESLA beam parameter specifications at a center-of-mass energy of 500 GeV. Realistic colliding beam distributions are used, which include dynamic effects of the beam transport from the Damping Rings to the Interaction Point. Beam-beam deflections scans and their impact for beam-based feedbacks are considered. A transverse kink instability is studied, including its impact on determining the luminosity-weighted center-of-mass energ…
We develop theoretical expressions for the luminosity and beam-beam tune shifts in the presence of both a crossing angle and hourglass effects for the present and next generation of symmetric e$^+$-e$^-$ colliders. The theory is applied to the design of the Fermilab site filler Higgs factory and to the FCC-ee collider.
A Super Flavor Factory, an asymmetric energy e+e- collider with a luminosity of order 10^36 cm-2s-1, can provide a sensitive probe of new physics in the flavor sector of the Standard Model. The success of the PEP-II and KEKB asymmetric colliders in producing unprecedented luminosity above 10^34 cm-2s-1 has taught us about the accelerator physics of asymmetric e+e- colliders in a new parameter regime. Furthermore, the success of the SLAC Linear Collider and the subsequent work on the International Linear Collider allow a new Super-Flavor collider to also incorporate linear collider techniques. …
Our beam-beam parameter study using beam-beam simulations and PWFA (particle-driven plasma acceleration) beam parameters indicates that at 3 TeV, for examined electron beam lengths ${2~μ\mathrm{m}\leqσ_z\leq 10~μ\mathrm{m}}$, the total luminosity, as well as the sharpness of the luminosity spectrum for a $γγ$ collider are independent of the beam length of the electron beams used to scatter the photons, given that the hourglass effect is avoided. The total luminosity can consequently be maximised by minimising the horizontal and vertical beta functions $β_{x,y}^*$ at the interaction point. Furt…
A formula of luminosity of asymmetric e+e- collider with coupled lattices is derived explicitly. The calculation shows how the tilted angle and aspect ratio of the beams affect the luminosity. Knowing the result of the calculation, we measure the tilted angle of the luminous region of the collision for PEP-II using two dimensional transverse scan of the luminosity. The method could be applied to correct the coupling at the collision point.
Below we review the LHC luminosity progress in 2010, discuss the luminosity evolution of the Tevatron collider at different stages of the Collider Runs, emphasize general dynamics of the process, compare with the performance of the other colliders analyze planned and delivered luminosity integrals, and discuss the expectation management lessons.
We discuss possible acceleration scenarios and methods for a mu+ mu- collider. The accelerator must take the beams from ~100 MeV to 2 TeV within the muon lifetime (2.2 x 10**(-6) E(mu)/m(mu) uS), while compressing bunches of 10**(12) muons from m to cm bunch lengths. Linac, recirculating linac, and very rapid-cycling synchrotron approaches are studied. Multiple recirculating linac approaches are matched to the muon lifetime and appear readily feasible. Rapid-cycling approaches require innovations in magnet designs and layouts, but could be much more affordable.
Recent simulations have shown that a high-energy proton bunch can excite strong plasma wakefields and accelerate a bunch of electrons to the energy frontier in a single stage of acceleration. This scheme could lead to a future $ep$ collider using the LHC for the proton beam and a compact electron accelerator of length 170 m, producing electrons of energy up to 100 GeV. The parameters of such a collider are discussed as well as conceptual layouts within the CERN accelerator complex. The physics of plasma wakefield acceleration will also be introduced, with the AWAKE experiment, a proof of princ…
We perform a beam-beam parameter study for a TeV-scale PWFA (particle-driven plasma wakefield acceleration) $\mathrm{e}^+$$\mathrm{e}^-$ linear collider using GUINEA-PIG simulations. The study shows that the total luminosity follows the $1/\sqrt{σ_z}$-scaling predicted by beamstrahlung theory, where $σ_z$ is the rms beam length, which is advantageous for PWFA, as short beam lengths are preferred. We also derive a parameter set for a 3 TeV PWFA linear collider with main beam parameters optimised for luminosity and luminosity spread introduced by beamstrahlung. Lastly, the study also compare the…
We describe here the latest results of calculations with FlexPDE code of wake-fields induced by the bunch in micro-structures. These structures, illuminated by swept laser bust, serve for acceleration of charged particles. The basis of the scheme is a fast sweeping device for the laser bunch. After sweeping, the laser bunch has a slope ~45o with respect to the direction of propagation. So the every cell of the microstructure becomes excited locally only for the moment when the particles are there. Self-consistent parameters of collider based on this idea allow consideration this type of collid…
With the best of modern standard lasers, high-energy $γγ$ colliders from electron beams of E larger than 250 GeV are only possible at the expense of photon luminosity, i.e. 10 times lower than for photon colliders at c.m. energies below 0.5 TeV. For existing state-of-the art lasers, an optimistic upper energy limit for x=4.8 is an electron beam of less than 250 GeV. This Snowmass21 Contributed Paper shows how Free Electron Lasers (FEL) pave the way for High Energy & High Luminosity $γγ$ colliders. We present and assess a conceptual design study of a FEL with wavelength of 2.4 $μ$m and an x-fac…
New physics is being explored with the Large Hadron Collider at CERN and with Intensity Frontier programs at Fermilab and KEK. The energy scale for new physics is known to be in the multi-TeV range, signaling the need for a future collider which well surpasses this energy scale. We explore a 10$^{\,34}$ cm$^{-2}$ s$^{-1}$ luminosity, 100 TeV $p\bar{p}$ collider with 7$\times$ the energy of the LHC but only 2$\times$ as much NbTi superconductor, motivating the choice of 4.5 T single bore dipoles. The cross section for many high mass states is 10 times higher in $p\bar{p}$ than $pp$ collisions. …
In response to a request from the CERN Scientific Policy Committee (SPC), the machine parameters and expected luminosity performance for several proposed post-LHC collider projects at CERN are compiled: three types of hadron colliders (HL-LHC upgrade, FCC-hh and HE-LHC), a circular lepton collider (FCC-ee), a linear lepton collider (CLIC), and three options for lepton-hadron colliders (LHeC, HE-LHeC, and FCC-eh). Particular emphasis is put on availability, physics run time, and efficiency. The information contained in this document was presented at the SPC Meeting of September 2018. It will se…
Plasma wake-field acceleration is one of the main technologies being developed for future high-energy colliders. Potentially, it can create a cost-effective path to the highest possible energies for e+e- or γ-γ colliders and produce a profound effect on the developments for high-energy physics. Acceleration in a blowout regime, where all plasma electrons are swept away from the axis, is presently considered to be the primary choice for beam acceleration. In this paper, we derive a universal efficiency-instability relation, between the power efficiency and the key instability parameter of the t…
Current searches for a dark photon in the mass range below 1 GeV require an electron-positron collider with a luminosity at the level of at least $10^{34}$ cm$^{-2}$s$^{-1}$. The challenge is that, at such low energies, the collider luminosity rapidly drops off due to increase in the beam sizes, strong mutual focusing of the colliding beams, and enhancement of collective effects. Using recent advances in accelerator technology such as the nano-beam scheme of SuperKEK-B, high-current Energy Recovery Linacs (ERL), and magnetized beams, we propose a new configuration of an electron-positron colli…
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 production 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 firs…
A precise determination of absolute luminosity, using the bremsstrahlung process, at the future Electron-Ion Collider (EIC) will be very demanding, and its three major challenges are discussed herein. First, the bremsstrahlung rate suppression due to the so-called beam size effect has to be well controlled. Secondly, the impact of huge synchrotron radiation fluxes should be mitigated. Thirdly, enormous bremsstrahlung event rates, in excess of 10 GHz, have to be coped with. A basic layout of the luminosity measurement setup at the EIC, addressing these issues, is proposed, including preliminary…
We point out that even the most intense laser beams available today can provide only a very small fraction of the beam energy required to reach the design luminosity for a future e+e- linear collider. This fact seems to have been overlooked in the extensive literature on laser acceleration of charged particles.
Construction of future Muon Collider tangential to the Large Hadron Collider will give opportunity to realize mu-p collisions at multi-TeV center of mass energies. Using nominal parameters of high luminosity and high energy upgrades of the LHC, as well as design parameters of muon colliders, it is shown that L_mu-p of order of 10^33 cm^-2s^-1 is achievable for different options with sqrt(s)_mu-p from 4.58 TeV to 12.7 TeV. Certainly, proposed mu-p colliders have a huge potential for clarifying QCD basics and searches for new physics.
The International Linear Collider (ILC) is a proposed electron-positron collider with a center-of-mass energy of 500~GeV, and a peak luminosity of $2 \cdot 10^{34}~\mathrm{cm}^{-2}\mathrm{s}^{-1}$. The ILC will complement the Large Hadron Collider, a proton-proton accelerator, and provide precision measurements, which may help in solving some of the fundamental questions at the frontier of scientific research, such as the origin of mass and the possible existence of new principles of nature. The linear collider community has set a goal to achieve a precision of $10^{-4}$ on the luminosity meas…
HL-LHC federates the efforts and R&D of a large international community towards the ambitious HL- LHC objectives and contributes to establishing the European Research Area (ERA) as a focal point of global research cooperation and a leader in frontier knowledge and technologies. HL-LHC relies on strong participation from various partners, in particular from leading US and Japanese laboratories. This participation will be required for the execution of the construction phase as a global project. In particular, the US LHC Accelerator R&D Program (LARP) has developed some of the key technologies fo…
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 ring 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 dipo…
We review the different performance limitations of circular colliders, namely the limitations of energy reach, maximum attainable luminosity and beam lifetime. This paper considers only head-on collisions. We consider the range of beam energies from 45GeV to 250 GeV and collider circumferences from 20 to 100kms.
Linear colliders (LC) on the energy 0.5-1 TeV are considered as the next step in the particle physics. High acceleration gradients, small beam sizes, precision tolerances, beam collision effects are main problems for linear colliders. In this paper we discuss physics motivation, parameters and status of current LC projects, e+e-, gamma-gamma and gamma-electron modes of operation, physical limitations on the energy and luminosity. Present technologies allow to reach energies about 5 TeV with adequate luminosities. Advanced technique based on plasma and laser method of acceleration can provide m…
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…
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. Th…
The high energy physics advantages, disadvantages and luminosity requirements of hadrons, of leptons and photon-photon colliders are considered. Technical arguments for increased energy in each type of machine are presented. Their relative size, and the implications of size on cost are discussed.
Several transverse noise sources, such as power supply ripples, can potentially act as an important limiting mechanism for the luminosity production of the Large Hadron Collider (LHC) and its future High-Luminosity upgrade (HL-LHC). In the presence of non-linearities, depending on the spectral components of the power supply noise and the nature of the source, such a mechanism can increase the diffusion of the particles in the distribution through the excitation of sideband resonances in the vicinity of the ones driven by the lattice non-linearities. For the HL-LHC, due to the reduction of the …
Gamma-proton collisions allow unprecedented investigations of the low x and high $Q^{2}$ regions in quantum chromodynamics. In this paper, we investigate the luminosity for "ILC"$\times$LHC ($\sqrt{s_{ep}}=1.3$ TeV) and "CLIC"$\times$LHC ($\sqrt{s_{ep}}=1.45$ TeV) based $γp$ colliders. Also we determine the laser properties required for high conversion efficiency.
Alternative Lattice Design for the STCF Collider Rings
University of Science and Technology of China（中国科学技术大学）；Budker Institute of Nuclear Physics SB RAS（布德克核物理研究所）；KEK（高能加速器研究机构）；The Graduate University for Advanced Studies (SOKENDAI)（日本高级研究院）；National Synchrotron Radiation Laboratory, University of Science and Technology of China（中国科学技术大学国家同步辐射实验室）
Particle acceleration in dielectric microstructures powered by infrared lasers, or "dielectric laser acceleration" (DLA), is a promising area of advanced accelerator research with the potential to enable more affordable and higher-gradient accelerators for energy frontier science and a variety of other applications. DLA leverages well-established industrial fabrication capabilities and the commercial availability of tabletop lasers to reduce cost, with axial accelerating fields in the GV/m range. Desirable luminosities would be obtained by operating with very low charge per bunch but at extrem…
