Ions for LHC: Beam Physics and Engineering Challenges

Physical Review Special Topics - Accelerators and Beams, 2004

A low beam-loss budget is an essential requirement for high-intensity machines and represents one of their major design challenges. In a high-intensity heavy-ion machine, losses are required to be below 1 W/m for hands-onmaintenance. The driver linac of the Rare Isotope Accelerator (RIA) is designed to accelerate beams of any ion to energies from 400 MeV per nucleon for uranium up to 950 MeV for protons with a beam power of up to 400 kW. The high intensity of the heaviest ions is achieved by acceleration of multiple-charge-state beams, which requires a careful beam dynamics optimization to minimize effective emittance growth and beam halo formation. For beam loss simulation purposes, large number of particles must be tracked through the linac. Therefore the computer code TRACK [1] has been parallelized. Calculations are being performed on the JAZZ cluster [2] recently inaugurated at ANL. This paper discusses how this powerful tool is being used for simulations for the RIA project to help decide on the highperformance and cost-effective design of the driver linac.

2007 IEEE Particle Accelerator Conference (PAC), 2007

The LHC beam dump system must function safely with 208 Pb 82+ ions. The differences with respect to the LHC proton beams are briefly recalled, and the possible areas for performance concerns discussed, in particular the various beam intercepting devices and the beam instrumentation. Energy deposition simulation results for the most critical elements are presented, and the conclusions drawn for the lead ion operation. The expected performance of the beam instrumentation systems are reviewed in the context of the damage potential of the ion beam and the required functionality of the various safety and post-operational analysis requirements.

Journal de Physique IV (Proceedings), 2006

Key scientific results from recent experiments, modeling tools, and heavy ion accelerator research are summarized that explore ways to investigate the properties of high energy density matter in heavy-ion-driven targets, in particular, strongly-coupled plasmas at 0.01 to 0.1 times solid density for studies of warm dense matter, which is a frontier area in high energy density physics. Pursuit of these near-term objectives has resulted in many innovations that will ultimately benefit heavy ion inertial fusion energy. These include: neutralized ion beam compression and focusing, which hold the promise of greatly improving the stage between the accelerator and the target chamber in a fusion power plant; and the Pulse Line Ion Accelerator (PLIA), which may lead to compact, low-cost modular linac drivers.

Journal of Physics: Conference Series, 2019

A design study for a future collider to be built in the LHC tunnel, the High-Energy Large Hadron Collider (HE-LHC), has been launched as part of the Future Circular Collider (FCC) study at CERN. It would provide proton collisions at a centre-of-mass energy of 27 TeV as well as collisions of heavy ions at the equivalent magnetic rigidity. HE-LHC is being designed under the stringent constraint of using the existing tunnel and therefore the resulting lattice and optics differ in layout and phase advance from the LHC. It is necessary to evaluate the performance of the collimation system for ion beams in HE-LHC in addition to proton beams. In the case of ion beams, the fragmentation and electromagnetic dissociation that relativistic heavy ions can undergo in collimators, as well as the unprecedented energy per nucleon of the HE-LHC, requires dedicated simulations. Results from a study of collimation efficiency for the nominal lead ion (208 Pb 82+) beams performed with the SixTrack-FLUKA coupling framework are presented. These include loss maps with comparison against an estimated quench limit as well as detailed considerations of loss spikes in the superconducting aperture for critical sections of the machine such as the dispersion suppressors.

IEEE Transactions on Nuclear Science

Traditional Heavy Ion testing for Single Event Effects is carried out in cyclotron facilities with energies around 10 MeV/n. Despite their capability of providing a broad range of Linear Energy Transfer (LET) values, the main limitations are related to the need of testing in vacuum and with the sensitive region of the components accessible to the low range ions. In this work we explore the use of Ultra-High Energy (5-150 GeV/n) ions in the CERN accelerator complex for radiation effects on electronics testing. At these energies we show, both through simulations and experimental data, the significant impact of the ion energy on the ionization track structure and associated volume-restricted LET value, highlighting the possible limitations for Radiation Hardness Assurance for high-energy accelerator applications. In addition, we show that from a nuclear interaction perspective, Ultra-High energy ions behave similarly to protons independently of their significantly larger mass.

2004

A sizeable part of the LHC physics programme foresees lead-lead collisions with a design luminosity of 10 27 cm -2 s -1 . This will be achieved after an upgrade of the ion injector chain comprising Linac3, LEIR, PS and SPS machines . Each LHC ring will be filled in 10 min by almost 600 bunches, each of 7×10 7 lead ions. Central to the scheme is the Low Energy Ion Ring (LEIR) , which transforms long pulses from Linac3 into highbrilliance bunches by means of multi-turn injection, electron cooling and accumulation. Major limitations along the chain, including space charge, intrabeam scattering, vacuum issues and emittance preservation are highlighted. The conversion from LEAR (Low Energy Antiproton Ring) to LEIR involves new magnets and power converters, high-current electron cooling, broadband RF cavities, and a UHV vacuum system with getter (NEG) coatings to achieve a few 10 -12 mbar. Major hardware changes in Linac3 and the PS are also covered. An early ion scheme with fewer bunches (but each at nominal intensity) reduces the work required for early LHC ion operation in spring 2008.

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 1987

An injector system has been constructed to provide heavy ion beams for the CERN accelerators. In the initttal step, an ECR (electron cyclotron resonance) source produces an 06+ ion beam, which is accelerated in an RFQ (radiofrequency quadrupole) structure from 5.6 keV/u to 139.5 keV/u. The specifications of this preaccelerator are described and results of test measurements at GSI are presented, as well as first experience at CERN. Oxygen ions have been accelerated in the CERN machines to 200 GeV/u. An upgrading program for the acceleration of sulphur or calcium is presented.

Proceedings Particle Accelerator Conference

In this paper, we discuss ion effects relevant to future storage rings and linear colliders. We ®rst review the conventional ion effects observed in present storage rings and then discuss how these effects will differ in the next generation of rings and linacs. These future accelerators operate in a new regime because of the high current long bunch trains and the very small transverse beam emittances. Usually, storage rings are designed with ion clearing gaps to prevent ion trapping between bunch trains or beam revolutions. Regardless, ions generated within a single bunch train can have signi®cant effects. The same is true in transport lines and linacs, where typical vacuum pressures are relatively high. Amongst other effects, we address the tune spreads due to the ions and the resulting ®lamentation which can severely limit emittance correction techniques in future linear colliders, the bunch-to-bunch coupling due to the ions which can cause a multi-bunch instability with fast growth rates, and the betatron coupling and beam halo creation which limit the vertical emittance and beam lifetimes.

Physical Review Special Topics - Accelerators and Beams, 2010

The paper presents results of FLUKA simulations of the residual activity induced by heavy ions in two target configurations representing: (1) a beam pipe of an accelerator and (2) a bulky accelerator structure like a magnet yoke or a coil. The target materials were stainless steel and copper representing the most common construction materials used for basic accelerator components. For these two materials, the inventory of the induced isotopes depends mainly on the target material and much less on the projectile species. Time evolution of the induced activity can be described by means of a generic curve that is independent from the projectile mass. Dependence of the induced residual activity on selected ion beam parameters was studied. The main goal of the study was establishing a scaling law expanding the existing proton beam-loss tolerance to heavy-ion beams. This scaling law enables specifying beam-loss criteria for projectile species from proton up to uranium at energies from 200 MeV=u up to 1 GeV=u.