arXiv subjects

Walter Scandale

Publications and source records attributed to Walter Scandale.

3 recordsLinked to original sources

arXiv2025

Dechanneling Population at Extreme Crystal Bending with 6.5 TeV Proton Beam

Beam measurements with bent crystals, installed in the Large Hadron Collider to assist multistage collimation system, provided information on hadron interactions with crystals in the multi-TeV energy range. In particular, the dechanneling population was observed through scans of deflected halo with collimators. Taking advantage of the fact that crystals with different values of curvature radii were present, the dependence of dechanneling on bending radius (R) was recorded. Dechanneling was found to be enhanced in crystals with smaller bending radius, because it is too close to the critical value R_c at the LHC energy of 6.5 TeV where channeling is lost. Data analysis and comparison to simulation results provided a better understanding of the phenomena and could be used to define specifications for more performing crystals in future upgrades of the crystal collimation system.

hep-ex↗

arXiv2025

Crystal Collimation Cleaning Measurements with 6.5 TeV protons in the LHC

Safe disposal of beam halo is a fundamental requirement of modern superconductive hadron colliders to reduce thermal load on magnets and background to experimental detectors. In the CERN Large Hadron Collider (LHC) a multistage system fully compliant with the needs of the baseline operation was build. At a later stage, two short bent crystals were interleaved to the devices for betatron collimation to investigate efficiency enhancement of the halo disposal when inserting them as primary stages of the collimation hierarchy. Each crystal was mounted on a high--accuracy angular actuator, called goniometer, and installed in the clockwise Beam 1, one for the horizontal and one for the vertical plane. In this paper, measurements of the cleaning performance at collision energy with and without inserting crystals in the standard collimation schemes are discussed; the results are compared to theoretical expectations.

physics.acc-ph↗

arXiv2023

HL-LHC layout for fixed-target experiments in ALICE based on crystal-assisted beam halo splitting

The Large Hadron Collider (LHC) at the European Organization for Nuclear Research (CERN) is the world's largest and most powerful particle accelerator colliding beams of protons and lead ions at energies up to 7 ZTeV, Z is the atomic number. ALICE is one of the detector experiments optimised for heavy-ion collisions. A fixed-target experiment in ALICE is being considered to collide a portion of the beam halo, split using a bent crystal inserted in the transverse hierarchy of the LHC collimation system, with an internal target placed a few meters upstream of the existing detector. This study is carried out as a part of the Physics Beyond Collider effort at CERN. Fixed-target collisions offer many physics opportunities related to hadronic matter and the quark-gluon plasma to extend the research potential of the CERN accelerator complex. Production of physics events depends on the particle flux on target. The machine layout for the fixed-target experiment is developed to provide a flux of particles on the target high enough to exploit the full capabilities of the ALICE detector acquisition system. This paper summarises the fixed-target layout consisting of the crystal assembly, the target and downstream absorbers. We discuss the conceptual integration of these elements within the LHC ring, the impact on ring losses, and expected performance in terms of particle flux on target.

physics.acc-ph↗