The lay-out of the photon collider at the international linear collider

One of the interaction regions at the linear colliders should be compatible both with e ⁺ e ⁻ and γγ, γe modes of operation. In this paper, the differences in requirements and possible design solutions are discussed.      

Ultimate parameters of the photon collider at the international linear collider

At linear colliders, the e ⁺ e ⁻ luminosity is limited by beam-collision effects, which determine the required emittances of beams in damping rings (DRs). In γγ collisions at the photon collider, these effects are absent, and so smaller emittances are desirable. In the present damping ring 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 small as possible. This can be achieved by adding more wigglers to the DRs; the incremental cost is easily justified by a considerable potential improvement of the γγ luminosity. No expert analysis exists as of now, but it seems realistic to obtain a factor five increase of the γγ luminosity compared to the ‘nominal’ DR design.      

Physics at the linear collider

The physics at the plannede ⁺ e ^- colliders is discussed around three main topics corresponding to different manifestations of symmetry breaking:W physics in the no Higgs scenario, studies of the properties of the Higgs and precision tests of SUSY. A comparison with the LHC is made for all these cases. The γγ mode of the linear collider will also be reviewed.     

Linear collider flavour identification status report: Sensors for the international linear collider

The Linear Collider Flavour Identification (LCFI) collaboration is continuing the work to develop column-parallel CCDs (CPCCD) and CMOS readout chips to be used in the vertex detector at the international linear collider (ILC). The CPCCD achieves several orders of magnitude faster readout than conventional CCDs because every column is equipped with amplifier and ADC, enabling efficient data taking with low occupancy. Already two generations of CPCCDs and readout chips have been manufactured and the first chips have been fully tested. The second generation devices are now being evaluated. A new CCD-based device, the in-situ storage image sensor (ISIS) has also been developed. The ISIS offers numerous advantages in terms of relaxed readout, increased radiation hardness and great immunity to EMI. In this paper we present the results from the tests of the CPCCDs, readout chips and ISIS, as well as the plans for future developments. for the Linear Collider Flavour Identification (LCFI) Collaboration     

The LHC collider

The first three year run of the Large Hadron Collider (LHC) ended in the spring of 2013. During this period, the collider was operated mainly at beam energies of 3.5 and 4 TeV. The performances that have been achieved during that first run and the challenges for commissioning and operating the LHC are presented. A brief outlook into the upcoming run at an energy of 6.5 TeV will be given.     

High-energy collider parameters

<正>HIGH-ENERGY COLLIDER PARAMETERS:e~+e~-Colliders(I)Updated in September 2013 with numbers received from representatives of the colliders(contact J.Beringer,LBNL).The table shows parameter values as achieved by July 1,2013.Quantities are,where appropriate,r.m.s.;unless noted otherwise,energies refer to beam energy;H and V indicate horizontal and vertical directions;s.c.stands for superconducting.Parameters for the defunct SPEAR,DORIS,PETRA,PEP,TRISTAN,and VEPP-2M colliders may be found in our 1996 edition(Phys.Rev.D54,1 July 1996,Part I).     

The LEP collider

The LEP collider and the performances which have been achieved are presented in simple terms. Some basic facts of electron circular machine physics are recalled. The ambitious and very successful programmes undertaken to maximize LEP luminosity and energy are described in detail. To cite this article: R. Bailey et al., C. R. Physique 3 (2002) 1107–1120.     

Coherent instabilities in the NICA collider

The thresholds of coherent beam instabilities in the NICA collider are analyzed in the present work. Studies were limited on the coherent oscillations in one of the rings due to the weakness of the beam-beam interaction forces when compared to the single-beam Coulomb forces. The thresholds of the single-beam and multiple-beam instabilities are estimated for the chosen collider operation scenario. Measures that have to be taken to suppress the instabilities are discussed.     

Coherent bremsstrahlung at the HERA collider

We consider a new type of radiation at colliders with short bunches—coherent bremsstrahlung (CBS) which is the radiation of the first bunch particles caused by the collective electromagnetic field of the second bunch. The number of CBS photons for a single collision isdN _λ ≈N ₀ dE _λ /E _λ > in the energy rangeE _λ ?E _c = 4γ ₁ ² ?c/l ₂. Hereγ ₁=E ₁/m ₁ c ²;l ₂ is the length of the opposing (second) bunch andN ₀ is proportional toN ₁ N ₂ ² whereN _j is thej-th bunch population. For the HERA colliderN ₀=14,E _c =73 eV in the case when photons are emitted by protons andN ₀=6·10⁷,E _c =24 keV—when photons are emitted by electrons. Unusual properties of such a coherent bremsstrahlung and the possibility to use CBS for fast beam steering and for luminosity optimization are discussed.     

The future linear collider

The future linear collider is an accelerator that is currently being proposed to collide electrons and positrons at energies ranging from ～90 GeV up to ～1 TeV. The physics potential of such a machine is described and the main features of the accelerator are outlined.     

VEPP-2000 collider commissioning

Construction of the VEPP-2000 construction was completed at the end of 2006. The first beam was captured in a special regime without final focus solenoids. In this regime, all systems of power supplies and machine control were calibrated and tuned. In the same mode vacuum chamber treatment by synchrotron radiation was performed with an electron beam current of up to 150 mA. The first test of the round beam option was performed at an energy of 508 MeV with a solenoidal field of 10 T in two straight sections of interaction. The text was submitted by the author in English.     

Electron-ion collider in China

Lepton scattering is an established ideal tool for studying inner structure of small particles such as nucleons as well as nuclei. As a future high energy nuclear physics project, an Electron-ion collider in China (EicC) has been proposed. It will be constructed based on an upgraded heavy-ion accelerator, High Intensity heavy-ion Accelerator Facility (HIAF) which is currently under construction, together with a new electron ring. The proposed collider will provide highly polarized electrons (with a po- larization of 80%) and protons (with a polarization of 70%) with variable center of mass energies from 15 to 20 GeV and the luminosity of (2–3)×10³³ cm−2•s−1. Polarized deuterons and Helium-3, as well as unpolarized ion beams from Carbon to Uranium, will be also available at the EicC.The main foci of the EicC will be precision measurements of the structure of the nucleon in the sea quark region, including 3D tomography of nucleon; the partonic structure of nuclei and the parton interaction with the nuclear environment; the exotic states, especially those with heavy flavor quark contents. In addition, issues fundamental to understanding the origin of mass could be addressed by measurements of heavy quarkonia near-threshold production at the EicC. In order to achieve the above-mentioned physics goals, a hermetical detector system will be constructed with cutting-edge technologies.This document is the result of collective contributions and valuable inputs from experts across the globe. The EicC physics program complements the ongoing scientific programs at the Jefferson Laboratory and the future EIC project in the United States. The success of this project will also advance both nuclear and particle physics as well as accelerator and detector technology in China.     

Measuring supersymmetry at the large hadron collider

The large hadron collider (LHC) should have the ability to detect supersymmetric particles if low-energy supersymmetry solves the hierarchy problem. Studies of the LHC detection reach, and the ability to measure properties of supersymmetric particles are currently underway. We highlight some of these, such as the reach in minimal supergravity space and correlation with a fine-tuning parameter, precision measurements of edge variables, anomaly or gauge-mediated supersymmetry breaking. Supersymmetry with baryon-number violation seems at first glance more difficult to detect, but proves to be possible by using leptons from cascade decays.     

The physics of the large hadron collider

The Large Hadron Collider (LHC) at CERN in Geneva, Switzerland, is the most powerful particle accelerator in the world. Its aim is to study the physics of elementary particles at the highest energies accessible to accelerators. It is believed that the Higgs boson (a last particle predicted by the Standard Model that is yet to be found) and the lightest particles of the Minimal Supersymmetric Model should be accessible at the LHC energies. These lectures give a short overview of the physics program and the technological challenges this collider faces.     

Intense ion-beam dynamics in the NICA collider

The problems of intense ion-beam dynamics in the developed and optimized optical structure of the NICA collider are considered. Conditions for beam collisions and obtaining the required parameters of luminosity in the operation energy range are discussed. The restriction on collider luminosity is related to effects of the domination of the space charge and intrabeam scattering. Applying methods of cooling, electron and stochastic ones, will permit one to suppress these effects and reach design luminosity. The work also deals with systems of magnetic field correction and problems of calculating the dynamic aperture of the collider.