Status of energy deposition studies IR7 A. Ferrari, M. Magistris, M. Santana, M. Silari, V. Vlachoudis Review of the LHC Collimation Project 30 June – 2 July 2004

Overview Introduction to beam collimation Main issues to be studied New features of FLUKA Implementation of the geometry Future work This talk is a status report of a work in progress. No results are available at the moment. The FLUKA input is ready and debugged, simulations are starting the first week of July.

Two warm LHC insertions dedicated to cleaning IR3, IR7 Collimation systems: Momentum and betatron cleaning Two beams

Principle of beam collimation IR7 Cleaning with collimators (warm) RR RR Dispersion suppressor (SC) π,e,p π,e,p π,e,p Beam 1 Primary collimators Damage? Secondary collimators Damage? SC magnets Quench?

Issues to be studied Energy deposition in collimators and downstream Damage to equipment in cleaning insertions Energy deposition in SC magnets in DS section Damage/perturbation to electronic equipment and cables Position of absorbers to cure problems These issues can be studied by means of the MC cascade code FLUKA.

FLUKA physics Physical models available for cross-checking: FLUKA standard model DPMJET 2.5 DPMJET 3 Possibility of simulating ions Single scattering for incident particles at grazing angle

FLUKA geometry New features of the latest version : repetition of objects according to symmetry transformation (rotation, translation, reflection, or combination of these). assignment of names to bodies and regions. These features allow implementing a complex geometry with a modular approach.

Advantages of the modular approach Time optimisation IR7 (more than 200 major components) can be implemented with less than 20 prototypes. Maintenance Any improvement in the prototype geometry applies to all replica in the tunnel. A new component can be added without modification of the existing geometry. Avoid duplicating efforts Every module can be used or modified by different users for future studies.

Prototypes Collimators, dipoles, quadrupoles, sextupoles, multipoles MB MQT

Reflection: MQW Vertical and Horizontal

Rotation and run-time corrections: Primary and secondary collimators Rotation around the beam direction and the vertical axis Jaw material (carbon, metal) Collimation gap and misalignment (run-time)

Additional components Beam Loss Monitors (air volume). Vacuum pipes (need for definition of bake-out equipment close to pipe  AT/VAC). Tunnel walls and estimates for cables. Electronic equipment in RR’s (K. Tsoulou).

A “flexible” geometry The magnetic fields and the beam loss distribution are described in user written routines. A specifically written program creates automatically the full geometry from an on-line file. Any change in component position, collimator rotation or jaw misalignment is automatically implemented. With minimal modifications, the same program can be used to implement different sections of LHC.

Special techniques and physics options Biasing techniques (“Russian roulette”, splitting, leading particle biasing and region importance) Energy threshold Electromagnetic cascade Particles to be tracked These options must be defined by the user according to the specific case studied.

IR7, Straight section

Summary Large initial effort to set up flexible and complete model of IR7 and cold dispersion suppressor. The straight section of IR7 is fully implemented. Prototypes and magnetic field of all components in DS have been implemented  adjusting positions. Full simulations starting first week of July. First complete picture: end of July.