96445234
Optics and lattice optimizations for the LHC upgrade project
The luminosity upgrade of the LHC collider at CERN is based on a strong focusing scheme to reach lowest values of the beta function at the collision points. Several issues have to be addressed in this context, that are considered as mid term goals for the optimisation of the lattice and beam optics: Firstly a number of beam optics have been developed to establish a baseline for the hardware R&D, and that will define the specifications for the new magnets that will be needed, in Nb3Sn as well as in NbTi technology. Secondly, the need for sufficient flexibility of the beam optics especially for smallest ! * values, the need for a smooth transition between the injection and the collision optics, the comparison of the optics performance between flat and round beams and finally different ways to optimise the chromatic correction, including the study of local correction schemes. This paper presents the status of this work, which is a result of an international collaboration, and summarises the main parameters that are foreseen to reach the HL-LHC luminosity goal.
52262880
SYNCHROTRON RADIATION STUDIES FOR A RING-RING LHeC INTERACTION REGION AND LONG STRAIGHT SECTION
The Large Hadron Electron Collider project is a proposal to study e-p and e-A interactions at the LHC. In the design for an electron synchrotron (alternative designs for a linac are also under development), a 60GeV e beam is collided with a 7TeV LHC proton beam to produce TeVscale collisions. Despite being much lower energy than the proton beam, the electron beam is high enough energy to produce significant amounts of synchrotron radiation (SR). This places strong constraints on beam optics and bending. In particular challenges arise with the complex geometry required by the long straight section (LSS) and interaction region (IR). This includes the coupled nature of the proton and electron optics, as SR produced by the electron beam must not be allowed to quench the superconducting proton magnets or create problems with beam-gas backgrounds. Despite this, the electron beam must be deflected significantly within the IR to produce sufficient separation from the proton beam.
116619220
Dark Matter Searches with ANTARES
15848028
PRECISION TESTS OF THE STANDARD MODEL AT LEP AND RESULTS FROM THE 4-JET FINAL STATE AT LEP 1.5
First a short review is made of current limits on the Standard Model as derived from the electroweak sector concerning the Z boson at LEP. The second part of the paper presents an analysis of the four jet nal state at ALEPH, this analysis was performed on LEP data taken at centre of mass energies of 130 and 136 GeV. The results presented here are from approximate totals 1 of 12.3 millionhadronic Z decays and 1.3 million leptonic decays recorded by the four LEP experiments during the years 1990 to 1995 inclusive. These statistics permit a precise study of the Standard Model though the coupling of the Z boson to fermion pairs. This reaction is modiied by vacuum polarization corrections in the propogator such as t-quark and Higgs boson loops thus allowing a determination of m top and m Higgs to be made via indirect measurements. It should be noted that results for 1993 onwards are regarded as preliminary for all 4 LEP experiments. In order to combine electroweak results a common reference point is required. Each of the LEP experiments measures the leptonic and hadronic total cross-sections and the leptonic forward-backward asymmetries from angular distributions in cos. These results are tted 1 according to the Z 0 lineshape to give 9 parameters, namely the Z boson mass and width, (m Z , ? Z), the pole hadronic cross-section, (0 h), the ratios of the hadronic to leptonic partial widths, (R e , R , R) and the leptonic pole asymmetries (A 0; e FB ,A 0; FB ,A 0; FB). These 9 parameters are then combined 1 , along with the individual experimental covariance matices and common systematic errors to give the results in Table 1. The nal two entries in Table 1 represent the values of the partial width ratio and the pole asymmetry under the assumption of lepton universality. This assumption is further explored in Figure 1 where R ` is plotted against A 0;` FB individually for the 3 lepton species and also under the assumption of lepton universality. The accuracy of these results is remarkable, with the Z boson mass being measured to 24 parts per million.