Lifetime, cross-sections and activation

The concept of cross-section and its relation to the beam lifetime in accelerators is being introduced. Some general properties of cross-sections for different particles and different interaction types are discussed. For some specific cases of elastic and inelastic reactions the conditions for beam losses and the corresponding lifetime is derived. The basics of activation or induced radioactivity in accelerators are also discussed at the end of lecture

Absolute Luminosity from Machine Parameters

The expected rates for proton proton collisions in the LHC are rather high. Monitoring can be based on several detector components and different physics channels can be used together and should allow for a good accuracy in the relative luminosity determination. The accuracy in the absolute luminosity determination may soon be limited by the uncertainty in the knowledge of the proton proton cross section at the LHC energy. Here we discuss the possibility to determine the absolute luminosity in the LHC from machine parameters, which does not require the knowledge of particle cross sections

The simultaneous and nearly-collinear K0K^{0} beams for experiment NA48

A system of simultaneous and nearly-collinear beams of long- and short-lived neutral kaons has been installed and extensively studied. These beams form an integral part of the NA48 experiment at the CERN SPS, which aims to study direct CP-violation. The beam splitting is achieved by a novel application of a bent silicon crystal. The principles and design of these beams, as well as their performance are described

The simultaneous long- and short-lived neutral kaon beams for experiment NA48

Simultaneous, nearly-collinear beams of long- and short-lived neutral kaons are an essential feature of the precision CP-violation experiment NA48 *) at the SPS. The present report describes the design and performance of these beams in relation to the requirements of the experiment

The high-intensity hyperon beam at CERN

A high-intensity hyperon beam was constructed at CERN to deliver Sigma- to experiment WA89 at the Omega facility and operated from 1989 to 1994. The setup allowed rapid changeover between hyperon and conventional hadron beam configurations. The beam provided a Sigma-flux of 1.4 x 10^5 per burst at mean momenta between 330 and 345 Gev/c, produced by about 3 x 10^10 protons of 450 GeV/c . At the experiment target the beam had a Sigma-/pi- ratio close to 0.4 and a size of 1.6 x 3.7 cm^2. The beam particle trajectories and their momenta were measured with a scintillating fibre hodoscope in the beam channel and a silicon microstrip detector at the exit of the channel. A fast transition radiation detector was used to identify the pion component of the beam.Comment: 20 pages, 13 figures. Submitted to Nucl. Instr. Meth.

Beam losses from ultra-peripheral nuclear collisions between Pb ions in the Large Hadron Collider and their alleviation

Electromagnetic interactions between colliding heavy ions at the Large Hadron Collider (LHC) at CERN will give rise to localized beam losses that may quench superconducting magnets, apart from contributing significantly to the luminosity decay. To quantify their impact on the operation of the collider, we have used a three-step simulation approach, which consists of optical tracking, a Monte-Carlo shower simulation and a thermal network model of the heat flow inside a magnet. We present simulation results for the case of Pb ion operation in the LHC, with focus on the ALICE interaction region, and show that the expected heat load during nominal Pb operation is 40% above the quench level. This limits the maximum achievable luminosity. Furthermore, we discuss methods of monitoring the losses and possible ways to alleviate their effect.Comment: 17 pages, 20 figure

First observations of beam losses due to bound-free pair production in a heavy-ion collider

We report the first observations of beam losses due to bound-free pair production at the interaction point of a heavy-ion collider. This process is expected to be a major luminosity limit for the Large Hadron Collider (LHC) when it operates with 208Pb82+ ions because the localized energy deposition by the lost ions may quench superconducting magnet coils. Measurements were performed at the Relativistic Heavy Ion Collider (RHIC) during operation with 100 GeV/nucleon 63Cu29+ ions. At RHIC, the rate, energy and magnetic field are low enough so that magnet quenching is not an issue. The hadronic showers produced when the single-electron ions struck the RHIC beampipe were observed using an array of photodiodes. The measurement confirms the order of magnitude of the theoretical cross section previously calculated by others.Comment: 4 pages, 5 figures. Added journal ref. Corrected typos. Fixed fig 1. Minor improvements to fig. 1,3,4. Rephrased a small number of sentences (p1,3,4). Added numerical values of the aperture and the displacement for Au (p 2). Changed reference 5, added name in acknowledgments (p 4