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Y. Nosochkov

Publications and source records attributed to Y. Nosochkov.

At least 19 recordsLinked to original sources

Machine Layout and Performance

Chapter 2 in High-Luminosity Large Hadron Collider (HL-LHC) : Preliminary Design Report. The Large Hadron Collider (LHC) is one of the largest scientific instruments ever built. Since opening up a new energy frontier for exploration in 2010, it has gathered a global user community of about 7,000 scientists working in fundamental particle physics and the physics of hadronic matter at extreme temperature and density. To sustain and extend its discovery potential, the LHC will need a major upgrade in the 2020s. This will increase its luminosity (rate of collisions) by a factor of five beyond the original design value and the integrated luminosity (total collisions created) by a factor ten. The LHC is already a highly complex and exquisitely optimised machine so this upgrade must be carefully conceived and will require about ten years to implement. The new configuration, known as High Luminosity LHC (HL-LHC), will rely on a number of key innovations that push accelerator technology beyond its present limits. Among these are cutting-edge 11-12 tesla superconducting magnets, compact superconducting cavities for beam rotation with ultra-precise phase control, new technology and physical processes for beam collimation and 300 metre-long high-power superconducting links with negligible energy dissipation. The present document describes the technologies and components that will be used to realise the project and is intended to serve as the basis for the detailed engineering design of HL-LHC.

physics.acc-ph

Status of the Super-B factory Design

The SuperB international team continues to optimize the design of an electron-positron collider, which will allow the enhanced study of the origins of flavor physics. The project combines the best features of a linear collider (high single-collision luminosity) and a storage-ring collider (high repetition rate), bringing together all accelerator physics aspects to make a very high luminosity of 10$^{36}$ cm$^{-2}$ sec$^{-1}$. This asymmetric-energy collider with a polarized electron beam will produce hundreds of millions of B-mesons at the $Υ$(4S) resonance. The present design is based on extremely low emittance beams colliding at a large Piwinski angle to allow very low $β_y^\star$ without the need for ultra short bunches. Use of crab-waist sextupoles will enhance the luminosity, suppressing dangerous resonances and allowing for a higher beam-beam parameter. The project has flexible beam parameters, improved dynamic aperture, and spin-rotators in the Low Energy Ring for longitudinal polarization of the electron beam at the Interaction Point. Optimized for best colliding-beam performance, the facility may also provide high-brightness photon beams for synchrotron radiation applications.

physics.acc-ph

Design of an interaction region with head-on collisions for the ILC

An interaction region (IR) with head-on collisions is considered as an alternative to the baseline configuration of the International Linear Collider (ILC) which includes two IRs with finite crossing-angles (2 and 20 mrad). Although more challenging for the beam extraction, the head-on scheme is favoured by the experiments because it allows a more convenient detector configuration, particularly in the forward region. The optics of the head-on extraction is revisited by separating the e+ and e- beams horizontally, first by electrostatic separators operated at their LEP nominal field and then using a defocusing quadrupole of the final focus beam line. In this way the septum magnet is protected from the beamstrahlung power. Newly optimized final focus and extraction optics are presented, including a first look at post-collision diagnostics. The influence of parasitic collisions is shown to lead to a region of stable collision parameters. Disrupted beam and beamstrahlung photon losses are calculated along the extraction elements.

physics.acc-ph

The 2 mrad crossing-angle ILC interaction region and extraction line

A complete optics design for the 2mrad crossing angle interaction region and extraction line was presented at Snowmass 2005. Since this time, the design task force has been working on developing and improving the performance of the extraction line. The work has focused on optimising the final doublet parameters and on reducing the power losses resulting from the disrupted beam transport. In this paper, the most recent status of the 2mrad layout and the corresponding performance are presented.

physics.acc-ph

The 2mrad horizontal crossing angle IR layout for a TeV ILC

The current status of the 2mrad crossing angle layout for the ILC is reviewed. The scheme developed in the UK and France is described and the performance discussed for a TeV machine. Secondly, the scheme developed at SLAC and BNL is then studied and modified for a TeV machine. We find that both schemes can handle the higher energy beam with modifications, and share many common features.

physics.acc-ph

Tracking Simulations Near Half-Integer Resonance at PEP-II

Beam-beam simulations predict that PEP-II luminosity can be increased by operating the horizontal betatron tune near and above a half-integer resonance. However, effects of the resonance and its synchrotron sidebands significantly enhance betatron and chromatic perturbations which tend to reduce dynamic aperture. In the study, chromatic variation of horizontal tune near the resonance was minimized by optimizing local sextupoles in the Interaction Region. Dynamic aperture was calculated using tracking simulations in LEGO code. Dependence of dynamic aperture on the residual orbit, dispersion and distortion of beta function after correction was investigated.

physics.acc-ph

Lattice with Smaller Momentum Compaction Factor for PEP-II High Energy Ring

At present, the PEP-II bunch length and vertical beta function at the Interaction Point (IP) are about of the same size. To increase luminosity, it is planned to gradually reduce the IP beta function. For the maximum effect, bunch length has to be also reduced to minimize luminosity loss caused by the hourglass effect at IP. One of the methods to achieve a smaller bunch length is to reduce momentum compaction factor. This paper discusses a lattice option for the High Energy Ring, where the nominal 60 degree cells in four arcs are replaced by 90 degree cells to reduce momentum compaction factor by 30% and bunch length by 16%. The increased focusing in 90 degree cells results in 40% stronger arc quadrupoles and 150% stronger arc sextupoles due to reduced dispersion and larger chromaticity. Tracking simulations predict that dynamic aperture for this lattice will be more than 10 times the rms size of a fully coupled beam for a horizontal emittance of 30 nm and IP beta function of 1cm. The lattice modification and results of simulations are presented.

physics.acc-ph

Tuning Knobs for the NLC Final Focus

Compensation of optics errors at the Interaction Point (IP) is essential for maintaining maximum luminosity at the NLC. Several correction systems (knobs) using the Final Focus sextupoles have been designed to provide orthogonal compensation of linear and the second order optics aberrations at IP. Tuning effects of these knobs on the 250 GeV beam were verified using tracking simulations.

physics.acc-ph

NLC Luminosity as a Function of Beam Parameters

Realistic calculation of NLC luminosity has been performed using particle tracking in DIMAD and beam-beam simulations in GUINEA-PIG code for various values of beam emittance, energy and beta functions at the Interaction Point (IP). Results of the simulations are compared with analytic luminosity calculations. The optimum range of IP beta functions for high luminosity was identified.

physics.acc-ph

Study of the NLC Linac Optics Compatible with a Low Energy Scenario

We explore the NLC linac optics compatible with a low energy scenario where initially only part of the full linac is installed. Optics modification suitable for a low energy beam running and upgrade to the nominal energy is discussed. Linac parameters and beam tolerances in the modified lattice are compared to the nominal design.

physics.acc-ph

Study of Low beta-y Straight Section in SPEAR 3

The SPEAR 3 light source has two 7.6 m straight sections one of which is available for new insertion devices (ID). By reducing the vertical beta function at the center of the straight from 9.8 m to 1.5 m, the beam size can be decreased from 44 to 17 microns to reduce the ID gap, but the ID length may be limited by the increased beta-y variation in the ID. Alternatively, a ``double waist'' optics with two symmetric low beta-y locations and a chicane may be considered to implement two IDs. In this paper, we discuss the low beta-y optics, effects on the beam dynamic aperture, and the ID parameters needed to maximize photon flux density and brightness while maintaining electron beam lifetime.

physics.acc-ph

Study of Beam Energy Spectrum Measurement in the NLC Extraction Line

The NLC extraction line provides a secondary focal point with a low beta function and 2 cm dispersion which can be used for measurement of the beam energy spectrum. In this study, tracking simulations were performed to transport the 0.5 TeV electron beam from the Interaction Point (IP) to the secondary focus (SF), ``measure'' the resultant transverse beam profile and reconstruct the disrupted IP energy spread. In the simulation, the obtained energy spectrum reproduced the initial IP spread reasonably well, especially with the vertical dispersion at SF which provides larger ratio of dispersion to the betatron beam size.

physics.acc-ph

NLC Beam Properties and Extraction Line Performance with Beam Offset at IP

Properties of the disrupted NLC beam at the Interaction Point (IP) and particle loss in the extraction line are analyzed as a function of beam-to-beam position and angular offset at IP. The simulations show that disruption and beam loss maximize when the vertical beam separation at IP is about 20 times the rms vertical beam size. The horizontal offset does not increase the disruption and the beam loss. The angular offsets cause particle loss in the extraction line mainly because of the beam orbit oscillations.

physics.acc-ph

The Next Linear Collider Extraction Line Design

The two main functions of the NLC extraction line include: 1) transmission of the outgoing disrupted beam and secondary particles to the dump with minimal losses; and 2) beam diagnostics and control. In this report, we describe the extraction line optics, present the results of tracking studies, and discuss the extraction line instrumentation.

physics.acc-ph

Dynamic Aperture Studies for SPEAR 3

The SSRL is investigating an accelerator upgrade project to replace the present 130 nm rad FODO lattice with an 18 nm rad double bend achromat lattice: SPEAR 3. In this paper, we review the methods used to maximize the SPEAR 3 dynamic aperture including optimization of linear optics, betatron tune, chromaticity and coupling correction, and effects of machine errors and insertion devices.

physics.acc-ph

Effect of Insertion Devices in SPEAR 3

The SPEAR 3 upgrade lattice will provide much reduced beam emittance to increase the brightness of synchrotron radiation beams from wigglers and undulators. Seven existing insertion devices will be used in the lattice. In this paper we review the wiggler parameters, outline the wiggler compensation scheme, and evaluate wiggler effect on the optics and dynamic aperture.

physics.acc-ph

Lattice and Compensation Schemes for the PEP-II Interaction Region

The PEP-II interaction region is designed to accommodate asymmetric beam energies, head-on collisions, small bunch spacing and provide low beta* for high luminosity. Local correction schemes are implemented to compensate non-linear chromaticity from the IP doublets as well as coupling, orbit and focusing effects from the 6 Tm asymmetric detector solenoid. The main IR optics features and local correction schemes are presented. MAD code is used for the optics calculations.

physics.acc-ph

Dynamic Aperture Studies for SPEAR 3

The Stanford Synchrotron Radiation Laboratory is investigating an accelerator upgrade project that would replace the present 130 nm rad FODO lattice with an 18 nm rad double bend achromat (DBA) lattice: SPEAR 3. The low emittance design yields a high brightness beam, but the stronger focusing in the DBA lattice increases chromaticity and beam sensitivity to machine errors. To ensure efficient injection and long Touschek lifetime, an optimization of the design lattice and dynamic aperture has been performed. In this paper, we review the methods used to maximize the SPEAR 3 dynamic aperture including necessary optics modifications, choice of tune and phase advance, optimization of sextupole and coupling correction, and modeling effects of machine errors, wigglers and lattice periodicity.

physics.acc-ph