Two 6 t beam dumps, made of a graphite core encapsulated in a stainless steel vessel, are used to absorb the energy of the two Large Hadron Collider (LHC) intense proton beams during operation of the accelerator. Operational issues started to appear in 2015 during LHC Run 2 (2014–2018) as a consequence of the progressive increase of the LHC beam kinetic energy, necessitating technical interventions in the highly radioactive areas around the dumps. Nitrogen gas leaks appeared after highly energetic beam impacts and instrumentation measurements indicated an initially unforeseen movement of the dumps. A computer modelling analysis campaign was launched to understand the origin of these issues, including both Monte Carlo simulations to model the proton beam interaction as well as advanced thermo-mechanical analyses. The main findings were that the amount of instantaneous energy deposited in the dump vessel leads to a strong dynamic response of the whole dump and high accelerations (above 200 g). Based on these findings, an upgraded design, including a new support system and beam windows, was implemented to ensure the dumps' compatibility with the more intense beams foreseen during LHC Run 3 (2022–2025) of 539 MJ per beam. In this paper an integral overview of the operational behaviour of the dumps and the upgraded configurations are discussed.
This study presents a further step within the ongoing R&D activities for the redesign of the CERN's Antiproton Decelerator Production Target (AD-Target). A first scaled target prototype, constituted of a sliced core made of ten Ta rods −8 mm diameter, 16 mm length-embedded in a compressed expanded graphite (EG) matrix, inserted in a 44 mm diameter Ti-6Al-4V container, has been built and tested under proton beam impacts at the CERN's HiRadMat facility, in the so called HRMT-42 experiment. This prototype has been designed following the lessons learned from previous numerical and experimental works (HRMT-27 experiment) aiming at answering the open questions left in these studies. Velocity data recorded on-line at the target periphery during the HRMT-42 experiment is presented, showing features of its dynamic response to proton beam impacts. Furthermore, x-ray and neutron tomographies of the target prototype after irradiation have been performed. These non-destructive techniques show the extensive plastic deformation of the Ta core, but suggest that the EG matrix can adapt to such deformation, which is a positive result. The neutron tomography successfully revealed the internal state of the tantalum core, showing the appearance of voids of several hundreds of micrometers, in particular in the downstream rods of the core. The possible origin of such voids is discussed while future microstructure analysis after the target opening will try to clarify their nature.
For antiproton production at CERN, high‐energy (26 GeV/c), intense, and short proton beams are impacted into a small rod—target core—made of a dense metal. Temperature rises in the order of 2000°C, and subsequent dynamic stresses of several gigapascals are induced in this rod every time it is impacted by the primary proton beam. Several R&D activities have been launched with the goal of proposing and manufacturing a new design of such device (named AD‐Target). A summary of these activities is presented, including the last design stage, which involves the manufacturing and testing of six real‐scale prototypes of the new target design. These prototypes (named PROTAD) consist of air‐cooled Ti‐6Al‐4V assemblies filled by matrices made of isostatic graphite or expanded graphite (EG), containing target cores made of small rods with different diameters (from 2 to 10 mm) of multiple grades of Ta, Ta2.5W, and Ir.
A new beam dump has been designed, built, installed and operated to withstand the future proton beam extracted from the proton synchrotron booster (PSB) in the framework of the LHC Injector Upgrade (LIU) Project at CERN. The future proton beam consists of up to 1 × 10 14 protons per pulse at 2 GeV and is foreseen after the machine upgrades planned for CERN's Long Shutdown 2 (2019-2020). In order to be able to efficiently dissipate the heat deposited by the primary beam, the new dump was designed as a cylindrical block assembly, made out of a copper alloy and cooled by forced airflow. In order to determine the energy density distribution deposited by the beam in the dump, Monte Carlo simulations were performed using the FLUKA code, and thermomechanical analyses were carried out by importing the energy density into ANSYS ®. In addition, computational fluid dynamics (CFD) simulations of the airflow were performed in order to accurately estimate the heat transfer convection coefficient on the surface of the dump. This paper describes the design process, highlights the constraints and challenges of integrating a new dump for increased beam power into the existing facility and provides data on the operation of the dump.
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