The Beam Loss Detection System of the LHC Ring

At the Large Hadron Collider (LHC) a beam loss system will be installed in the arc, dispersion suppressor and the straight regions for a continuous surveillance of particle losses. These beam particles deposit their energy partially in the super-conducting coils leading to temperature increase, possible magnet quenches and damages. The primary and secondary halo of the beam is absorbed by the collimation system. The tertiary halo will be lost at aperture limits in the ring. Its loss distribution along the magnets has been studies. At the positions, where most of the beam losses are expected, simulations of the particle fluences outside the cryostat and induced by lost protons at the aperture have been performed with the Monte Carlo Code Geant 3.2.1. This allows determining the most suitable positions of the detectors, the needed number of monitors and the impact on the dynamic range of the detectors. The design of the beam loss monitor system is presented that meet the required sensitivity, dynamic range and time resolution

LHC beam loss monitor system design

At the LHC a beam loss system will be installed for continuous surveillance of particle losses. The system is designed to prevent hardware destructions, to avoid magnet coil quenches and to provide quantitative loss values. Over 3000 ionization chambers will be used to initiate the beam abort if the loss rates exceed the quench levels. The time and beam energy dependent quench levels require the acquisition of chamber currents in the range from 50 pA to 0.5 mA and an update of the values every 89 mu s. The acquisition and control electronics will consist of a front end electronics near (< 400 m) to the ionization chambers and a threshold controller in the surface buildings. The front end will include a charge balance converter, a counter and multiplexer part. The charge balance converter is most suitable to cover the large dynamic range. The introduced error is smaller than few % in the required dynamic range. Six channels will be transmitted over one cable of up to 3 km length. The threshold controller will issue warnings and dump signals depending on the beam energy and the loss durations. (7 refs)

Do indirect questions reduce lying about corruption? Evidence from a quasi-field experiment

Recent studies have found reticent managers are less likely to report corruption than are non-reticent managers. We confirm this using new data from Bangladesh and Sri Lanka. We find reticence greatly affects estimates of corruption for measures based on both direct and indirect questions. We also find reticence affects response rates. Surprisingly, reticent managers were less likely to refuse to answer questions on corruption than non-reticent managers, possibly because reticent managers believe that refusing to answer seems like a tacit admission of guilt. Throughout the analysis, we control for the potential endogeneity of the reticence measure