IPAC2011 - List of Authors (Timmins, M.A.)

Paper	Title	Page
TUPS035	LHC Collimators with Embedded Beam Position Monitors: A New Advanced Mechanical Design	1611
	A. Dallocchio, A. Bertarelli, C.B. Boccard, F. Carra, M. Gasior, L. Gentini, M.A. Timmins CERN, Geneva, Switzerland
	The LHC collimation system, ensuring both functions of beam cleaning and machine protection, is potentially submitted to high-energy beam impacts. Currently the collimators setup is performed by monitoring beam losses generated by the collimator jaws when approaching the particle beam. This procedure is applied to all LHC collimators (almost one hundred), taking several hours, and needs to be repeated if beam settings change significantly. Furthermore, during the beam-based alignment, the LHC tertiary collimators are potentially exposed to abnormal losses entailing possible damage to their tungsten jaws. To improve the efficiency of the machine operation and better control the particle beam a new advanced design embedding Beam Position Monitors (BPM) into the movable collimator jaws has been developed. This paper describes the mechanical design of various types of future collimators with embedded BPMs. Experimental measurements performed on a simplified functional prototype installed in the CERN SPS showed that, thanks to on-board BPMs, the collimator could be precisely, rapidly, and safely aligned and the beam position accurately measured.

TUPS036	High Energy Beam Impacts on Beam Intercepting Devices: Advanced Numerical Methods and Experimental Set-up	1614
	A. Bertarelli, V. Boccone, F. Carra, F. Cerutti, A. Dallocchio, N. Mariani, M.A. Timmins CERN, Geneva, Switzerland L. Peroni, M. Scapin Politecnico di Torino, Torino, Italy
	Funding: This work has been carried out through of the European Coordination for Accelerator Research and Development (EuCARD), co-sponsored by EU 7th Framework Program. Beam Intercepting Devices are potentially exposed to severe accidental events triggered by direct impacts of energetic particle beams. State-of-the-art numerical methods are required to simulate the behavior of affected components. A review of the different dynamic response regimes is presented, along with an indication of the most suited tools to treat each of them. The consequences on LHC Tungsten Collimators of a number of beam abort scenarios were extensively studied, resorting to a novel category of numerical explicit methods, named Hydrocodes. Full shower simulations were performed providing the energy deposition distribution. Structural dynamics and shock wave propagation analyses were carried out with varying beam parameters, identifying important thresholds for collimator operation, ranging from onset of permanent damage up to catastrophic failure. Since the main limitation of these tools lies in the limited information available on constitutive material models under extreme conditions, a dedicated experimental program is proposed, relying on the HiRadMat test facility at CERN. Experimental aspects such as sample-holder design and test set-up are described.

Paper

Title

Page

LHC Collimators with Embedded Beam Position Monitors: A New Advanced Mechanical Design

1611

A. Dallocchio, A. Bertarelli, C.B. Boccard, F. Carra, M. Gasior, L. Gentini, M.A. Timmins
CERN, Geneva, Switzerland

The LHC collimation system, ensuring both functions of beam cleaning and machine protection, is potentially submitted to high-energy beam impacts. Currently the collimators setup is performed by monitoring beam losses generated by the collimator jaws when approaching the particle beam. This procedure is applied to all LHC collimators (almost one hundred), taking several hours, and needs to be repeated if beam settings change significantly. Furthermore, during the beam-based alignment, the LHC tertiary collimators are potentially exposed to abnormal losses entailing possible damage to their tungsten jaws. To improve the efficiency of the machine operation and better control the particle beam a new advanced design embedding Beam Position Monitors (BPM) into the movable collimator jaws has been developed. This paper describes the mechanical design of various types of future collimators with embedded BPMs. Experimental measurements performed on a simplified functional prototype installed in the CERN SPS showed that, thanks to on-board BPMs, the collimator could be precisely, rapidly, and safely aligned and the beam position accurately measured.

TUPS036

High Energy Beam Impacts on Beam Intercepting Devices: Advanced Numerical Methods and Experimental Set-up

1614

A. Bertarelli, V. Boccone, F. Carra, F. Cerutti, A. Dallocchio, N. Mariani, M.A. Timmins
CERN, Geneva, Switzerland
L. Peroni, M. Scapin
Politecnico di Torino, Torino, Italy

Funding: This work has been carried out through of the European Coordination for Accelerator Research and Development (EuCARD), co-sponsored by EU 7th Framework Program.
Beam Intercepting Devices are potentially exposed to severe accidental events triggered by direct impacts of energetic particle beams. State-of-the-art numerical methods are required to simulate the behavior of affected components. A review of the different dynamic response regimes is presented, along with an indication of the most suited tools to treat each of them. The consequences on LHC Tungsten Collimators of a number of beam abort scenarios were extensively studied, resorting to a novel category of numerical explicit methods, named Hydrocodes. Full shower simulations were performed providing the energy deposition distribution. Structural dynamics and shock wave propagation analyses were carried out with varying beam parameters, identifying important thresholds for collimator operation, ranging from onset of permanent damage up to catastrophic failure. Since the main limitation of these tools lies in the limited information available on constitutive material models under extreme conditions, a dedicated experimental program is proposed, relying on the HiRadMat test facility at CERN. Experimental aspects such as sample-holder design and test set-up are described.