One of the key-issues to increase the luminosity in the next generation particle factories is to reduce the bunch length at the interaction point (IP) as much as possible. This will allow reducing proportionally the transverse beta functions at the IP and increasing the luminosity by the same factor. The strong RF focusing consists in obtaining short bunches by substantially increasing the lattice momentum compaction and the RF gradient. In this regime the bunch length is modulated along the ring and could be minimized at the IP. If the principal impedance generating elements of the ring are located where the bunch is long (in the RF cavities region) it is possible to avoid microwave instability and excessive bunch lengthening due to the potential well distortion.
Plasma wake lens in which all short relativistic electron bunches of sequence are focused identically and uniformly is studied analytically and by numerical simulation. For two types of lenses necessary parameters of focused sequence of relativistic electron bunches are formulated. Verification of these parameters is performed by numerical simulation.
Electron storage rings of GeV energy with laser pulse stacking cavities are promising intense sources of polarised hard photons which, via pair production, can be used to generate polarised positron beams. Dynamics of electron bunches circulating in a storage ring and interacting with high-power laser pulses is studied both analytically and by simulation. Common features and differences in the behaviour of bunches interacting with an extremely high power laser pulse and with a moderate pulse are discussed. Also considerations on particular lattice designs for Compton gamma rings are presented.
The paper presents the results of numerical PIC-simulation of accelerated and drive bunches dynamics in a dielectric waveguide filled with radially inhomogeneous plasma. The wakefield was excited by the electron bunch in a quartz (permittivity 3.75) dielectric tube with outer and inner diameters of 1.2 mm and 1.0 mm, respectively, which was nested into a cylindrical metallic waveguide. The drive bunch characteristics were chosen to be: 5 GeV for electron energy, 3 nC for the charge, 0.2 mm - the bunch length, 0.9 mm - the bunch diameter. The accelerated bunch had the same parameters, except fo…
We examine through numerical calculation the collision of counter-propagating trains of optically spaced electron/positron microbunches in a 1 TeV collider scenario for a dielectric laser accelerator (DLA). A time-dependent envelope equation is derived for arbitrary number of bunches in the classical limit, with inclusion of the radiation reaction force (RRF). Example parameters are examined based on a constrained luminosity relation that takes into account the bunch charge for optimal efficiency, material damage limits, and power constraints. We find that for initially identical counter-propa…
University of Chicago（芝加哥大学）；Brookhaven National Laboratory（布鲁克海文国家实验室）；Fermi National Accelerator Laboratory（费米国家加速器实验室）；SLAC National Accelerator Laboratory（斯坦福直线加速器中心）
A train of short charged particle bunches can efficiently drive a strong plasma wakefield over a long propagation distance only if all bunches reside in focusing and decelerating phases of the wakefield. This is shown possible with equidistant bunch trains, but requires the bunch charge to increase along the train and the plasma frequency to be higher than the bunch repetition frequency.
Collider-quality electron bunches from an all-optical plasma photoinjector
Stony Brook University（石溪大学）；University of California, Los Angeles（加州大学洛杉矶分校）；University of Rochester（罗切斯特大学）；Brookhaven National Laboratory（布鲁克海文国家实验室）；University of Texas at Austin（德克萨斯大学奥斯汀分校）
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. …
By means of hollow plasma, multiple proton bunches work well in driving nonlinear plasma wakefields and accelerate electrons to energy frontier with preserved beam quality. However, the acceleration of positrons is different because the accelerating structure is strongly charge dependent. There is a discrepancy between keeping a small normalized emittance and a small energy spread. This results from the conflict that the plasma electrons used to provide focusing to the multiple proton bunches dilute the positron bunch. By loading an extra electron bunch to repel the plasma electrons and meanwh…
The efficiency of colliders for physics is largely determined by their luminosity, while most of the energy consumed by high-energy $e^+e^-$ colliders is proportional to the total beam current. Thus, the energy efficiency is mainly determined by the specific luminosity that needs to be maximized. One of the most effective ways to achieve this is by using the Crab waist collision scheme, which implies a large Piwinski angle (LPA). A distinctive feature of the FCC-ee is the great influence of beamstrahlung (radiation in the field of an opposite bunch) on beam dynamics. At low energies, this mani…
This paper presents one of the case studies of the Gamma Factory initiative -- a proposal of a new operation scheme of ion beams in the CERN accelerator complex. Its goal is to extend the scope and precision of the LHC-based research by complementing the proton-proton collision programme with the high-luminosity nucleus-nucleus one. Its numerous physics highlights include studies of the exclusive Higgs-boson production in photon-photon collisions and precision measurements of the electroweak (EW) parameters. There are two principal ways to increase the LHC luminosity which do not require an up…
