Machine Protection and High Energy Density States in Matter for High Energy Hadron Accelerators

The Large Hadron Collider (LHC) is the largest accelerator in the world. It is designed to collide two proton beams with unprecedented particle energy of 7TeV. The energy stored in each beam is 362MJ, sufficient to melt 500kg of copper. An accidental release of even a small fraction of the beam energy can result in severe damage to the equipment. Machine protection systems are essential to safely operate the accelerator and handle all possible accidents. This thesis deals with the study of different failure scenarios and its possible consequences. It addresses failure scenarios ranging from low intensity losses on high-Z materials and superconductors to high intensity losses on carbon and copper collimators. Low beam losses are sufficient to quench the superconducting magnets and the stabilized superconducting cables (bus-bars) that connects the main magnets. If this occurs and the energy from the bus-bar is not extracted fast enough it can lead to a situation similar to the accident in 2008 at LHC during powering tests. Inadequate beam aborts combined with failures in the collimation systemsetup can lead to severe damage on the tertiary collimators. One of the critical failures scenarios is when the entire beam is lost at a single point. Several failures at the LHC could lead to the full beam deflected with non-nominal angle, into a 10m long graphite absorber, into a septummagnet, or into superconducting magnets. This thesis presents detailed numerical simulations of the full LHC beam impact on carbon and SPS beam on copper. Simulations have been carried out employing a particle interaction and transport package, FLUKA, and a two-dimensional hydrodynamic code, BIG2. Results suggest the existence of a hydrodynamic process that boosts the beam penetration range. Results for LHC suggest that the beam can penetrate up to 25min carbon whereas the range of the shower from a single proton in carbon is just about 3m. This hydrodynamic effect is called ’hydrodynamic tunneling’. Hydrodynamic tunneling is the result of the extreme conditions (temperature and pressure) that occurs in the beam heated region of the target. A large part of the beam heated region enters into theWarmDenseMatter (WDM) state. An experiment to reproduce the hydrodynamic tunnelingwas performed at theHigh Radiation toMaterials (HiRadMat) facility at the CERN on July 2012. High intensity beamwas directed on a copper target. The experiment uses a new diamond detector designed for the high radiation environments. The experiment was also a good opportunity to investigate new types of instrumentation for high radiation environments: SEM detectors, strain gauges and temperature probes. Experiment results are consistent with hydrodynamic tunneling of protons.