On possible lower bounds for the direct detection rate of SUSY Dark Matter

One can expect accessible lower bounds for dark matter detection rate due to restrictions on masses of the SUSY-partners. To explore this correlation one needs a new-generation large-mass detector. The absolute lower bound for detection rate can naturally be due to spin-dependent interaction. Aimed at detecting dark matter with sensitivity higher than $10^{-5}$ event/day/kg an experiment should have a non-zero-spin target. Perhaps, the best is to create a GENIUS-like detector with both Ge-73 (high spin) and Ge-76 nuclei.Comment: latex, 5 pages, 3 figures. Talk given at the III International Conference on Non-accelerator New Physics (NANP'01), Dubna, 19--23 June, 200

Optimization of a short faraday cup for low-energy ions using numerical simulations

ISOLDE, the heavy-ion facility at CERN is undergoing a major upgrade with the installation of a superconducting LINAC that will allow post-acceleration of ion beams up to 10 MeV/u. In this framework, customized beam diag- nostics are being developed in order to fulfil the design re- quirements as well as to fit in the compact diagnostic boxes foreseen. The main detector of this system is a compact Faraday cup that will measure beam intensities in the range of 1 pA to 1 nA. In this contribution, simulation results of electrostatic fields and particle tracking are detailed for different Faraday cup prototypes taking into account the energy spectrum and angle of emission of the ion-induced secondary electrons

A continuous sampling scheme for edge illumination x-ray phase contrast imaging

We discuss an alternative acquisition scheme for edge illumination (EI) x-ray phase contrast imaging (XPCi) based on a continuous scan of the object, and compare its performance to that of a previously used scheme, which involved scanning the object in discrete steps rather than continuously. By simulating signals for both continuous and discrete methods under realistic experimental conditions, the e ect of the spatial sampling rate is analysed with respect to metrics such as image contrast and accuracy of the retrieved phase shift. Experimental results con rm the theoretical predictions. Despite being limited to a speci c example, the results indicate that continuous schemes present advantageous features compared to discrete ones. Not only can they be used to speed up the acquisition, but they also prove superior in terms of accurate phase retrieval. The theory and experimental results provided in this study will guide the design of future EI experiments through the implementation of optimised acquisition schemes and sampling rates

Luminosity measurements at LEP

Fast luminosity measurements are vital for the optimisation of the machine conditions needed for physics. At LEP this has been achieved since the startup by means of 16 small tungsen-silicon calorimeters measuring the rate of Bhabba scattering events. To increase the counting rate the detectors are placed close to the beams and mounted on collimator jaws. The rate of Bhabba scattering is calculated using the rate of coincidental detections of e- and e+ at both sides of the interaction point. The correction term arising from accidental off-momentum particle coincidence is calculated from the background rates. This technique could be successfully used at beam energies around 45 GeV since the correction term was small.Starting in '95 however, the energy of LEP has been increased up to 91.5 GeV per beam. In these conditions the background event rate almost doubles while the Bhabba cross section adopted and presented in this paper consists of checking the collinearity in the vertical plane of the particle tracks. This is obtained by measuring the vertical centre position of the showers inside the calorimeters using silicon strip detectors

Improved sensitivity at synchrotrons using edge illumination X-ray phase-contrast imaging

The application of the X-ray phase-contrast ‘edge illumination’ principle to the highly coherent beams available at synchrotron radiation facilities is presented here. We show that, in this configuration, the technique allows achieving unprecedented angular sensitivity, of the order of few nanoradians. The results are obtained at beamlines of two different synchrotron radiation facilities, using various experimental conditions. In particular, different detectors and X-ray energies (12 keV and 85 keV) were employed, proving the flexibility of the method and the broad range of conditions over which it can be applied. Furthermore, the quantitative separation of absorption and refraction information, and the application of the edge illumination principle in combination with computed tomography, are also demonstrated. Thanks to its extremely high phase sensitivity and its flexible applicability, this technique will both improve the image quality achievable with X-ray phase contrast imaging and allow tackling areas of application which remain unexplored until now

N2_2 and Xe Gas Scintillation Cross-Section, Spectrum, and Lifetime Measurements from 50 MeV to 26 GeV at the CERN PS and Booster

Beam parameters in CERN's Proton Synchrotron (PS) accelerator must be controlled (and measured) with tighter precision than ever before to meet the stringent requirements of the Large Hadron Collider (LHC) programme. A non-destructive beam profile measurement system would be a valuable diagnostic tool. To this end, we measured N2 and Xe gas scintillation absolute cross-sections and lifetimes for proton beam energies from 1.4 to 25 GeV, which should prove valuable in the design and construction of a gas scintillation profile measurement system. We also measured relative cross-sections for proton beam energies between 0.05 and 1.4 GeV

Model of Dipole Field Variations in the LEP Bending Magnets

The determination of the Z mass at LEP requires a knowledge of the relative beam energy in the order of 10 ppm, therefore it is essential to understand the dipole field variations to the same level of accuracy. In LEP the bending magnet field shows a relative increase of the order of 100 ppm over 10 hours, which was found to be caused by leakage currents from railways flowing along the vacuum cham ber and temperature variations. A LEP dipole test bench was set up for systematic investigations. Field variations were monitored with NMR probes while the cooling water temperature of both coil and vacuum chamber was kept under control. The results lead to a parametrisation of the magnetic field variation as a function of the vacuum chamber current and temperature

Status of the HIE-ISOLDE project at CERN

The HIE-ISOLDE project represents a major upgrade of the ISOLDE nuclear facility with a mandate to significantly improve the quality and increase the intensity and energy of radioactive nuclear beams produced at CERN. The project will expand the experimental nuclear physics programme at ISOLDE by focusing on an upgrade of the existing Radioactive ion beam EXperiment (REX) linac with a 40 MV superconducting linac comprising thirty-two niobium-on-copper sputter-coated quarter-wave resonators housed in six cryomodules. The new linac will raise the energy of post-accelerated beams from 3 MeV/u to over 10 MeV/u. The upgrade will be staged to first deliver beam energies of 5.5 MeV/u using two high-$\beta$ cryomodules placed downstream of REX, before the energy variable section of the existing linac is replaced with two low-$\beta$ cryomodules and two additional high-$\beta$ cryomodules are installed to attain over 10 MeV/u with full energy variability above 0.45 MeV/u. An overview of the project including a status summary of the different R&D activities and the schedule will outlined.Comment: 7 pages, 12 figures, submitted to the Heavy Ion Accelerator Technology conference (HIAT) 2012, in Chicag