985 research outputs found
Baseline LHC machine parameters and configuration of the 2015 proton run
This paper shows the baseline LHC machine parameters for the 2015 start-up.
Many systems have been upgraded during LS1 and in 2015 the LHC will operate at
a higher energy than before and with a tighter filling scheme. Therefore, the
2015 commissioning phase risks to be less smooth than in 2012. The proposed
starting configuration puts the focus on feasibility rather than peak
performance and includes margins for operational uncertainties. Instead, once
beam experience and a better machine knowledge has been obtained, a push in
and performance can be envisaged. In this paper, the focus is on
collimation settings and reach in ---other parameters are covered in
greater depth by other papers in these proceedings.Comment: submitted for publication in a CERN yellow report (Proceedings of the
LHC Performance Workshop - Chamonix 2014
Bankers on pricing consumer deposits
Bank deposits ; Interest ; Certificates of deposit ; Money market deposit account
A Method for Simultaneous Optimisation of Orbit and Dispersion in Storage Rings
An algorithm for the simultaneous optimisation of orbit and dispersion in a storage ring is presented. Based on orbit and dispersion measurements the algorithm determines the optimal corrector settings in order to simultaneously minimize the r.m.s orbit, the r.m.s dispersion and the r.m.s strenght of the dipoles correctors. A number of different options for error handling of beam position monitors, weighting, and correction have been introduced to ensure the stability of the algorithm in the environment of a large accelerator. Experimental results are presented for the LEP collider demonstrating the efficiency of the method. The use of this correction algorithm for LEP in 1999 allowed achieving about a factor of two smaller vertical emittances than in previous years
Beta-Beating Corrections in the SPS as a Testbed for the LHC
For several years optics measurement and correction algorithms have been developed for the LHC. During 2008 these algorithms have been tested in the SPS and RHIC. The experimental results proving the readiness of the applications are presented
Proposal to Increase the LEP Energy with Horizontal Orbit Correctors
In an e+ e- collider the beam energy depends only on the bending field integral "Bds while the synchrotron radiation power scales with "B2ds and is sensitive to the details of the field distribution. With fixed RF acceleration voltage it is thus possible to attain higher energies by increasing the effective bending magnet length. We propose to use the horizontal orbit correctors to exploit this effect. To control the orbit perturbations, 79 unused correctors in the regular arcs and 14 unused correctors in the dispersion suppressors will have to be powered. An energy increase of approximatively 0.18 GeV per beam might be obtained
90 m optics commissioning
http://accelconf.web.cern.ch/AccelConf/IPAC2011/papers/tupz001.pdfInternational audienceSpecial ÎČâ = 90 m optics have been developed for the two very high luminosity insertions of the LHC [1] [2], as a rst step to allow for very low angle precision measure- ments of the proton-proton collisions in the LHC. These optics were developed to be compatible with the stan- dard LHC injection and ramp optics. The target value of ÎČâ = 90 m is reached by an un-squeeze from the injection ÎČâ = 11 m. We report about the implementation of this op- tics and the rst experience gained in commissioning with beam during two machine studies
Dynamic Beam Based Calibration of Beam Position Monitors
The degree of spin polarization at LEP is strongly dependent on the knowledge of the vertical orbit. Quadrupole magnet alignment and beam position monitor (BPM) offsets are the main source of the orbi t uncertainty. The error of the orbit monitor readings can be largely reduced by calibrating the monitor relative to the adjacent quadrupole. At LEP, 16 BPM offsets can be determined in parallel durin g 40 minutes. The error of the measure offset is about 30mm. During the LEP run 1997, more than 500 measurements were made and used for the optimisation of polarization. The method of dynamic beam bas ed calibration will be explained and the results will be shown
Calibration of centre-of-mass energies at LEP 2 for a precise measurement of the W boson mass
The determination of the centre-of-mass energies for all LEP 2 running is
presented. Accurate knowledge of these energies is of primary importance to set
the absolute energy scale for the measurement of the W boson mass. The beam
energy between 80 and 104 GeV is derived from continuous measurements of the
magnetic bending field by 16 NMR probes situated in a number of the LEP
dipoles. The relationship between the fields measured by the probes and the
beam energy is defined in the NMR model, which is calibrated against precise
measurements of the average beam energy between 41 and 61 GeV made using the
resonant depolarisation technique. The validity of the NMR model is verified by
three independent methods: the flux-loop, which is sensitive to the bending
field of all the dipoles of LEP; the spectrometer, which determines the energy
through measurements of the deflection of the beam in a magnet of known
integrated field; and an analysis of the variation of the synchrotron tune with
the total RF voltage. To obtain the centre-of-mass energies, corrections are
then applied to account for sources of bending field external to the dipoles,
and variations in the local beam energy at each interaction point. The relative
error on the centre-of-mass energy determination for the majority of LEP 2
running is 1.2 x 10^{-4}, which is sufficiently precise so as not to introduce
a dominant uncertainty on the W mass measurement.Comment: 79 pages, 45 figures, submitted to EPJ
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