On The Implementation Of Experimental Solenoids In MAD-X And Their Effect On Coupling In The LHC

The betatron coupling introduced by the experimental solenoids in the LHC is small at injection and negligible at collision energy. We present a study of these effects and look at possible corrections. Additionally we report about the implementation of solenoids in the MAD-X program. A thin solenoid version is also made available for tracking purposes

Fusion Pores Live on the Edge.

Biological transmission of vesicular content occurs by opening of a fusion pore. Recent experimental observations have illustrated that fusion pores between vesicles that are docked by an extended flat contact zone are located at the edge (vertex) of this zone. We modeled this experimentally observed scenario by coarse-grained molecular simulations and elastic theory. This revealed that fusion pores experience a direct attraction toward the vertex. The size adopted by the resulting vertex pore strongly depends on the apparent contact angle between the adhered vesicles even in the absence of membrane surface tension. Larger contact angles substantially increase the equilibrium size of the vertex pore. Because the cellular membrane fusion machinery actively docks membranes, it facilitates a collective expansion of the contact zone and increases the contact angle. In this way, the fusion machinery can drive expansion of the fusion pore by free energy equivalents of multiple tens of k <sub>B</sub> T from a distance and not only through the fusion proteins that reside within the fusion pore

Хронотоп та жанрова специфіка дилогії «Шлях невідомого» і «Дім над кручею» Ігоря Качуровського

The article deals with the chronotop of dilogy «The road of the unknown» and «The house on the steep bank» by I. Kachurovsky as a factor of the artistic unity of the work and genre specificity. The core of «The road of the unknown» is a chronotop of the road on which various meetings are waiting for the hero during his travel to the native land. Linear adventurous time predominates. But in «The house on the steep bank» this type of time interlaces with the cyclic idyllic time. The volume of chronotop, its ability to incorporate the smaller chronotops, establish complicated relations between them and some other characteristics make it possible to determine the genre of the dilogy as a novel in short stories, and genre variety – as an adventurous-intellectual one

Beam Dynamics for the Preliminary Phase of the New CLIC Test Facility (CTF3)

In the framework of the CLIC (Compact Linear Collider) RF power source studies, the scheme of electron pulse compression and bunch frequency mulitiplication, using injection by RF deflectors into an isochronous ring, will be tested, at low charge, during the preliminary phase of the new CLIC Test Facility (CTF3) at CERN. In this paper, we describe the beam dynamics studies made in order to assess the feasibility of the bunch combination experiment, as well as the related beam measurements performed on the LEP Pre-Injector complex (LPI) before its transformation into CTF

Beam Dynamics for the CTF3 Preliminary Phase

In the framework of the CLIC RF power source studies, the new scheme of electron pulse compression and bunch frequency multiplication, using injection by RF deflectors into an isochronous ring, will be tested at CERN during the CTF3 preliminary phase. The present LPI complex will be modified in order to allow a test of this scheme at low charge. The design of the new front-end, of the modified linac, of the matched transfer line, and of the isochronous ring lattice is presented here.The results of the related beam dynamics studies are also discussed

A more robust and flexible lattice for LHC

To correct more efficiently the arc dispersion, the exact antisymmetry of the LHC optics is now broken, except in the low-b triplets common to the two rings. A new quadrupole is added between the experimental insertions and the dispersion suppressors and several arc quadrupoles are complemented by a small trim quadrupole. The larger number of parameters gives flexibility to the lattice and allows a partial separation of the optical functions, with a decrease of the total number of quadrupole units. It is possible to change rather freely the phase advances of the arc cells. The nominal tunes are split by 4 units to reduce coupling. The bin boot tuning range in the experimental low-b is significantly increased, allowing e.g. a larger beam separation at injection. The super-periodicity of LHC remains 1. We plan to study whether it can be increased within the LHC hardware constraint

A Low Charge Demonstration of Electron Pulse Compression for the CLIC RF Power Source

The CLIC (Compact Linear Collider) RF power source is based on a new scheme of electron pulse compression and bunch frequency multiplication using injection by transverse RF deflectors into an isochronous ring. In this paper, we describe the modifications needed in the present LEP Pre-Injector (LPI) complex at CERN in order to perform a low-charge test of the scheme. The design of the injector (including the new thermionic gun), of the modified linac, of the matched injection line, and of the isochronous ring lattice, are presented. The results of preliminary isochronicity measurements made on the present installation are also discussed.Comment: 3 pages, 5 figures, submitted to the LINAC 2000 Conferenc

Optics Flexibility and Dispersion Matching at Injection into the LHC

The LHC requires very precise matching of transfer line and LHC optics to minimise emittance blow-up and tail repopulation at injection. The recent addition of a comprehensive transfer line collimation system to improve the protection against beam loss has created additional matching constraints and consumed a significant part of the flexibility contained in the initial optics design of the transfer lines. Optical errors, different injection configurations and possible future optics changes require however to preserve a certain tuning range. Here we present methods of tuning optics parameters at the injection point by using orbit correctors in the main ring, with the emphasis on dispersion matching. The benefit of alternative measures to enhance the flexibility is briefly discussed

Dynamical aperture studies for the CERN LHC: comparison between statistical assignment of magnetic field errors and actual measured field errors

It is customary to evaluate the performance of a circular particle accelerator by computing the dynamical aperture, i.e. the domain in phase space where bounded singleparticle motion occurs. In the case of the LHC the dynamical aperture computation is performed by assuming a statistical distribution of the magnetic field errors of various magnets classes: the numerical computations are repeated for a given set of realisations of the LHC ring. With the progress in the magnet production and allocation of the available positions in the ring, the statistical approach has to be replaced by the computation of one single configuration, namely the actual realisation of the machine. Comparisons between the two approaches are presented and discussed in details.Â

CLIC Beam Delivery System

We review the present design for the CLIC beam delivery system as configured for 3 TeV and for 500 GeV, describe some recent developments (including the combined effect of solenoid, crab cavity, and crossing angle), highlight open questions, and outline future studies