Within the general frame of the upgrade of the collider DAFNE to the neutron-antineutron energy threshold (2-2.5 GeV c.m.), modifications and different options for the accelerator design are discussed and a possible lattice for the Main Rings at 1 GeV is presented. The luminosity required by the experiments for such a light quark factory is of the order of few 10^31 cm-2 s-1, easily achievable in the particle factory era.
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…
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}…
The Compact Linear Collider (CLIC) targets a nanometre beam size at the collision point. Realising this beam size requires the generation and transport of ultra-low emittance beams. Dynamic imperfections can deflect the colliding beams, leading to a collision with a relative offset. They can also degrade the emittance of each beam. Both of these effects can significantly impact the luminosity of CLIC. In this paper, we examine a newly considered dynamic imperfection: stray magnetic fields. Measurements of stray magnetic fields in the Large Hadron Collider tunnel are presented and used to devel…
This paper discusses recently proposed Higgs Energy LEptoN (HELEN) $e+e-$ linear collider based on advances in superconducting radio frequency technology. The collider offers cost and AC power savings, smaller footprint (relative to the ILC), and could be built at Fermilab with an interaction region within the site boundaries. After the initial physics run at 250 GeV, the collider could be upgraded either to higher luminosity or to higher (up to 500 GeV) energies.
A Muon Collider poses a number of challenging problems in the lattice design - low beta-star, small circumference, large physical and dynamic aperture - which must be solved in order to realize the unique opportunities it offers for the high-energy physics. This contribution presents basic solutions which make it possible to achieve the goals for both the energy frontier collider and the Higgs factory with Nb3Sn magnet parameters.
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.
We propose and demonstrate that a gamma-gamma collider with W_gg < 12 GeV can be added to the European XFEL with a minimal disruption to its main program. High-energy photons will be obtained by Compton scattering of 0.5 micron laser photons on the existing 17.5 GeV electron beams. Such a gamma-gamma collider would be an excellent place for the development and application of modern technologies: powerful lasers, optical cavities, superconducting linacs, and low-emittance electron sources -- as well as training the next generation of accelerator physicists and engineers. The physics program wou…
We discuss the main factors affecting the design of accelerators aiming to investigate physics at the GUT scale. The most important constraints turn out to be the energy used and the time taken to accumulate sufficient luminosity. We propose a photon collider design, where the photons are generated by undulator radiation from high energy muon beams. This reduces the energy requirements by a factor of more than $10^7$ compared to a pp collider. Much of the reduction in energy use is achieved by using a periodic magnetic field, and by splitting the muon wavefunctions spatially to reduce the phot…
As an alternative to Compton backscattering and bremsstrahlung, the process of colliding high-energy electron beams with strong laser fields can more efficiently provide both cleaner and brighter source of photons in the multi-GeV range for fundamental studies in nuclear and quark-gluon physics. In order to favor the emission of high-energy quanta and minimize their decay into electron-positron pairs the fields must not only be sufficiently strong, but also well localized. We here examine these aspects and develop the concept of a laser-particle collider tailored for high-energy photon generat…
The Technical Design Report (TDR) of the ILC mainly concentrates on a baseline machine of 500 GeV centre-of-mass with detailed cost and manpower estimates consistent with this option. However, the discovery of a Higgs Boson with a mass of 125 GeV opens up the possibility of reducing cost by starting at a centre-of-mass energy of 250 GeV with the possibility of future upgrades to 500 GeV or even 1 TeV should the physics case for such an upgrade be compelling. The rest of this paper outlines the options for the design of a 250 GeV "Higgs factory".
In this paper we present alternative approach for Future Circular electron-positron Collider. Current 100 km circumference design with the top CM energy of 365 GeV (182.5 GeV beam energy) is based on two storage rings to circulate colliding beams. One of the ring-ring design shortcomings is enormous power consumption needed to compensate for 100 MW of the beam energy losses for synchrotron radiation. We propose to use energy recovery linac located in the same tunnel to mitigate this drawback. We show in this paper that our approach would allow a significant, up to an order of magnitude, reduct…
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…
Limitation on the luminosity of e+e- storage rings due to beamstrahlung
在能量大于2 E ~140 GeV（迎头碰撞）和2 E ~40 GeV（蟹腰碰撞）的情况下，由于束流碰撞中单个高能束致辐射光子的发射而导致的粒子损失对储存环的亮度产生了基本的限制.在这些阈值能量以上，由于束辐射的抑制因子为1/E^{4/3}，并且对于固定功率的同步辐射，亮度L与R/E^{13/3}成比例，其中R是对撞机半径。对于2 E> 150 GeV，两种碰撞方案有相似的光度极限。在储存环和线性对撞机（LC）2 E =240 GeV希格斯工厂可达到的亮度是相当的;在更高的能量，LC是首选。这篇会议论文是基于我最近的PRL出版物[1]，补充了对直线加速器环e+e-对撞机和带电荷补偿的环e+e-对撞机（四束碰撞）的额外评论。
This Snowmass 2021 contributed paper discusses a Higgs-Energy LEptoN (HELEN) $e^+e^-$ linear collider based on advances superconducting radio frequency technology. The proposed collider offers cost and AC power savings, smaller footprint (relative to the ILC), and could be built at Fermilab with an Interaction Region within the site boundaries. After the initial physics run at 250 GeV, the collider could be upgraded either to higher luminosity or to higher (up to 500 GeV) energies. If the ILC could not be realized in Japan in a timely fashion, the HELEN collider would be a viable option to bui…
The Circular Electron Positron Collider (CEPC) is a large international scientific project initiated and hosted by China. It is located in a 100-km circumference underground tunnel. The accelerator complex consists of a linear accelerator (Linac), a damping ring (DR), the Booster, the Collider and several transport lines. In the tunnel, space is reserved for a future pp collider, SPPC. The CEPC center-of-mass energy is 240 GeV, and at that collision energy will serve as a Higgs factory. The design also allows operation at 91 GeV for a Z factory and at 160 GeV for a W factory. The heart of the …
