Fixed target project AFTER at the LHC beams for heavy ion and hadron physics

High intensity proton and lead ion beams at the LHC collider allow one to use the beam halo by placing a fixed target or a bent crystal for beam extraction. The particle energy in this case is just half that at the RHIC collider, but the luminosity exceeds the collider luminosity many times. It is also possible to install a polarized target in the extracted beam. The project AFTER is aimed at investigation of rare processes, polarization phenomena, determination of the parameters required for analysis of cosmic rays and neutrino astrophysics, detailed investigation of quarkonia production and suppression depending on the phase transition of matter to the quark-gluon phase.     

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.      

Superbunch hadron colliders

A novel concept of a high luminosity hadron collider is proposed. This would be a typical application of an induction synchrotron being newly developed. Extremely long bunches, referred to as superbunches, are generated by a multibunch stacking method employing barrier buckets at the injection into the collider and are accelerated with a step voltage induced in the induction gaps. Superbunches intersect with each other, yielding a luminosity of more than 10(35) cm(-2) sec(-1). A combination of vertical crossing and horizontal crossing must be employed in order to avoid any significant beam-beam tune shift.     

Stochastic Cooling in the Startup and Project Configurations of the NICA Collider Equipment

The stochastic cooling system is a key element of the NICA accelerator–collider complex. The dependence of the luminosity on the β function at the interaction point is investigated, the main parameters of the system are substantiated, and the equipment mix for the startup and project modes of collider operation is described.     

Modeling the drift properties of gas mixtures of a GasPixel detector for upgrading the ATLAS setup

The results of modeling the drift properties of gas mixtures for a GasPixel detector that would provide highly accurate track data at high luminosity values in the inner detector of the ATLAS setup at the Super LHC collider are presented.     

Luminosity spectrum reconstruction at linear colliders

A good knowledge of the luminosity spectrum is mandatory for many measurements at future $\mathrm {e}^{+}\mathrm {e}^{-}$ colliders. As the beam-parameters determining the luminosity spectrum cannot be measured precisely, the luminosity spectrum has to be measured through a gauge process with the detector. The measured distributions, used to reconstruct the spectrum, depend on Initial State Radiation, cross-section, and Final State Radiation. To extract the basic luminosity spectrum, a parametric model of the luminosity spectrum is created, in this case the spectrum at the 3 TeV compact linear collider. The model is used within a reweighting technique to extract the luminosity spectrum from measured Bhabha event observables, taking all relevant effects into account. The centre-of-mass energy spectrum is reconstructed within 5 % over the full validity range of the model. The reconstructed spectrum does not result in a significant bias or systematic uncertainty in the exemplary physics benchmark process of smuon pair production.     

Whither colliders after the Large Hadron Collider?

This paper presents options for high-energy colliders at the energy frontier for the years to come. The immediate plans include the exploitation of the LHC at its design luminosity and energy as well as upgrades to the LHC (luminosity and energy) and to its injectors.?This may be complemented by a linear electron?Cpositron collider, based on the technology being developed by the Compact Linear Collider and by the International Linear Collider, by a high-energy electron?Cproton machine, the LHeC, and/or by a muon collider. This contribution describes the various future directions, all of which have a unique value to add to experimental particle physics, and concludes by outlining the key messages for the way forward.     

Status of the High-Voltage Electron-Cooling System of the NICA Collider

Physics of Particles and Nuclei Letters - In order to achieve the design luminosity in the NICA collider, it is planned to equip it with both stochastic and electron cooling. The electron-cooling...     

Top quark search beyond theW mass at tevatron collider energy

The upgraded Tevatron collider, with an expected integrated luminosity of 100 pb^?1, shall push up the top quark discovery limit from 80 to 200 GeV. The distinctive signature of the signal vis-a-vis background are analysed for this mass range of top.     

On the development of an ion-beam stochastic cooling system for the nuclotron superconducting accelerator complex

The Joint Institute for Nuclear Research (JINR) initiated the creation of a unique heavy-ion collider, the Nuclotron-based ion collider facility (NICA), which is planned to be put into commission in 2016. According to the calculation data, the collider luminosity, which should be kept at a record high level of 10²⁷ cm^?2 s^?1, will gradually decrease, mainly due to intrabeam scattering. To maintain luminosity at a high level, it is necessary to include a cooling system in the base project of the accelerator. Among the two cooling methods (electron and stochastic) most frequently used for heavy ion beams, stochastic cooling seems more attractive. However, there has been a lack of experience in the development and commissioning of such systems in Russia. For this reason, an experiment on stochastic cooling on the Nuclotron accelerator is being prepared to explore the technology and possibilities of this method. In this work, the method of stochastic cooling, the technique for calculating the cooling dynamics, and the experimental setup under development are briefly described.     

Discovery potential of Higgs boson pair production through 4■+■ final states at a 100 TeV collider

We explore the discovery potential of Higgs pair production at a 100 Te V collider via full leptonic mode.The same mode can be explored at the LHC when Higgs pair production is enhanced by new physics. We examine two types of fully leptonic final states and propose a partial reconstruction method, which can reconstruct some useful kinematic observables. It is found that the m T2 variable determined by this reconstruction method and the reconstructed visible Higgs mass are crucial to discriminate the signal and background events. It is also noticed that a new variable, denoted as ?m, which is defined as the mass difference of two possible combinations, is very useful as a discriminant. To examine the detector effects, we consider seven detector setups for a 100 Te V collider and investigate the changes in the sensitivity, and we find that lepton isolation and the minimal lepton P t cut are crucial in order to reduce the integrated luminosity.     

Luminosity Measurement and Control at NICA

Physics of Particles and Nuclei Letters - A detector for measuring the luminosity at beam crossing points at the NICA collider is proposed. This small detector is based on scintillation counters...     

DAΦNE status and upgrade plans

The Frascati Φ-factory DAΦNE has successfully completed experimental runs for the three main detectors, KLOE, FINUDA and DEAR. The best peak luminosity achieved so far is 1.6 × 10³² cm⁻² s⁻¹, while the best daily integrated luminosity is 10 pb⁻¹. At present the DAΦNE team is preparing an upgrade of the collider based on the novel crab waist collision scheme. The upgrade is aimed at pushing the luminosity towards 10³³cm⁻²s⁻¹. In this paper we describe present collider performance and discuss ongoing preparatory work for the upgrade. for DAΦNE Collaboration Team [1] The text was submitted by the author in English.     

Measurement of Integrated Luminosity at ψ(2S) by Wide-Angle Bhabha Scattering

A method for measuring the integrated luminosity of the e⁺ e^－ colliding experiment by using the wide-angle Bhabha events at the center of mass energy of the ψ(2S) resonance is presented. The determination of the integrated luminosity for the ψ(2S) data collected by the BES detector at the BEPC collider shows the feasibility of the method.     

Feasibility study of online tuning of the luminosity in a circular collider with the robust conjugate direction search method

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.     

Effective photon spectra for the photon colliders

The luminosity distribution in the effective mass at a photon collider usually has two peaks which are well separated: a high energy peak with mean energy spread about 5–7% and a wide low energy peak. The low energy peak strongly depends on the details of the design and is unsuitable for the study of new physics phenomena. We find a simple approximate form for the spectra of colliding photons for and colliders, whose convolution describes the high energy luminosity peak with a good accuracy in most of the essential preferable region of the parameters. Received: 14 September 1999 / Published online: 17 February 2000     

ON THE AVERAGE LUMINOSITY OF ELECTRON POSITRON COLLIDER AND POSITRON-PRODUING ENERGY

In this paper, the average luminosity of linac injected electron positron collider is investigated from the positron-producing energy point of view. When the energy of the linac injector is fixed to be less than the operating energy of the storage ring, it has been found that there exists a positron-producing energy to give optimum average luminosity. Two cases have been studied, one for an ideal storage ring with no single-beam instability and the other for practical storage ring with fast head-tail instability. The result indicates that there is a positron-producing energy corresponding to the minimum injection time, but this does not correspond to the optimum average luminosity for the practical storage rings. For Beijing Electron Positron Collider (BEPC), the positron-producing energy corresponding to the optimum average luminosity is about one tenth of the total injector energy.     

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.     

New generation electron-positron factories

In 2010 we celebrate 50 years since commissioning of the first particle storage ring ADA in Frascati (Italy) that also became the first electron-positron collider in 1964. After that date the particle colliders have increased their intensity, luminosity and energy by several orders of magnitude. Namely, because of the high stored beam currents and high rate of useful physics events (luminosity) the modern electron-positron colliders are called “factories”. However, the fundamental physics has required luminosities by 1–2 orders of magnitudes higher with respect to those presently achieved. This task can be accomplished by designing a new generation of factories exploiting the potential of a new collision scheme based on the Crab Waist (CW) collision concept recently proposed and successfully tested at Frascati. In this paper we discuss the performance and limitations of the present generation electron-positron factories and give a brief overview of new ideas and collision schemes proposed for further collider luminosity increase. In more detail we describe the CW collision concept and the results of the crab waist collision tests in DAϕNE, the Italian ϕ-factory. Finally, we briefly describe most advanced projects of the next generation factories based on the CW concept: SuperB in Italy, SuperKEKB in Japan and SuperC-Tau in Russia.     

Luminosity measuring processes at the LHC

We study the theoretical accuracy of various methods that have been proposed to measure the luminosity of the LHC pp collider, as well as for Run II of the Tevatron collider. In particular we consider methods based on (i) the total and forward elastic data, (ii) lepton-pair production and (iii) W and Z production. Received: 18 October 2000 / Revised version: 9 February 2001 / Published online: 15 March 2001