Beam-induced energy deposition issues in the Very Large Hadron Collider

Abstract

Energy deposition issues are extremely important in the Very Large Hadron Collider (VLHC) with huge energy stored in its 20 TeV (Stage-1) and 87.5 TeV (Stage-2) beams. The status of the VLHC design on these topics, and possible solutions of the problems are discussed. Protective measures are determined based on the operational and accidental beam loss limits for the prompt radiation dose at the surface, residual radiation dose, ground water activation, accelerator components radiation damage and quench stability. The beam abort and beam collimation systems are designed to protect accelerator from accidental and operational beam losses, IP region quadrupoles from irradiation by the products of beam-beam collisions, and to reduce the accelerator-induced backgrounds in the detectors. BEAM LOSS AND RADIATION VLHC SpecificThe VLHC beam [1], with about 3 GJ of kinetic energy, is almost an order of magnitude larger than the LHC. Under normal circumstances roughly 50% of this energy is gradually dissipated in beam-beam collisions at the interaction regions (IR). A few percent of the energy is lost diffusely due to beam-gas interactions around the ring, intercepted by beam collimation inserts, and dissipated in the RF loads as the beam is decelerated. Somewhere between 40% (intentional beam abort at the end of the store at normal operation) and 100% (unintentional beam abort at certain circumstances) of the beam energy can be deposited in the external beam absorbers. A beam collimation system is used to scrape away beam halo keeping most of the circumference beam loss "free", with just several regions where special care should be taken to mitigate the beam loss induced effects. The collimation region and IRs are the hottest regions in the machine and require special consideration.Under accidental conditions, there is enough energy to cause severe damage to the machine and detector components and environment. Obviously, if such a beam of a millimeter size goes astray, it will melt a hole through a magnet and do further damage outside the machine. The VLHC beam carries enough energy that in principle it could liquefy 400 liters of steel. Experience with Tevatron and our studies for LHC and VLHC show that with highly reliable beam abort system, highly efficient beam collimation system, local shields and a some additional measures, the machine, detector and environmental can be safely protected. * Work supported by the Universities Research Association, Inc., under contract DE-AC02-76CH03000 with the U. S. Department of Energy.† mokhov@fnal.govOn a large scale, muon fluxes around the machine can drive the complex layout and other related issues. Many other radiation issues, such as radiation damage to electronics and other sensitive equipment in the tunnel, radiation streaming to the surface through access and ventilation shafts, unsynchronized beam abort etc., are or will be attacked. Here we consider just a few most important issues. Superconducting MagnetsThe warm-iron design of the transmission line magnet of the...

Experimental and Numerical Studies on the Proposed Application of Hollow Electron Beam Collimation for the LHC at CERN

“…Considering projects such as the High Luminosity LHC (HL-LHC) at European Organization for Nuclear Research (CERN), which aims at increasing the luminosity of the LHC by a factor 10, or the Very Large Hadron Collider (VLHC), designed to operate at 20 × 20 TeV in Stage 1 and 88 × 88 TeV in Stage 2 [15], new innovative collimation techniques are required.…”

Beam Collimation at Hadron Colliders

“…Two-stage collimation systems were parts of the original designs in all the superconducting hadron collider projects: 3×3-TeV UNK at Protvino [10], 20×20-TeV SSC in Texas [1,2], 7×7-TeV LHC at CERN [11,12], 0.82-TeV proton HERA ring at DESY [13], 20×20-TeV (Stage-1) and 88×88-TeV (Stage-2) VLHC in Illinois [14].…”

“…The collimation system [14], designed for the 20×20-TeV Stage-1 VLHC, consists of horizontal and vertical primary collimators and a set of secondary collimators placed at optimal phase advances. From the very beginning, the lattice was designed to provide a warm collimation region with enough space to accommodate the system and provide large dispersion for those collimators which intercept the off-momentum protons.…”