URL: http://www.eurotev.org/e10/e19/index_eng.html

EUROTEV: EUROPEAN DESIGN STUDY TOWARDS A GLOBAL TEV LINEAR COLLIDER

EUROTeV

Work Packages

WP6: ILPS ·

WP6: Integrated Luminosity Performance Studies

Preservation of the ultra-small vertical emittance during the transport and acceleration from the damping ring to the interaction point will be a major challenge. Very tight tolerances are required on field quality and alignment of components, which are beyond those achievable with optical survey techniques. Hence, beam-based alignment as well as emittance and luminosity tuning procedures are essential. Dynamic effects such as ground motion and vibration will have significant detrimental effect on the luminosity if not actively compensated for using mechanical stabilisation and beam-based feedback systems. The dynamic effects may also significantly impact the initial beam-based alignment and tuning procedures, reducing their effectiveness: the ILC-TRC specifically acknowledged this last topic as a high ranking R&D item, noting the need for full simulations of the tuning including the dynamic effects and their compensation. To reliably predict the integrated luminosity performance of the linear collider computer simulations are essential. A central aim of WP6 is to provide the required reliable computer models to study the machine performance with a wide variety of static and dynamic imperfections. A second area of activity is the modelling of beam halo generation, and the performance of the halo collimation systems necessary to shield the physics detector from unacceptable background. A final step is to amalgamate the two studies (codes), enabling us to study the impact of errors, luminosity tuning and feedback systems on halo-induced background and background tuning.

Primary Objectives of the WP6

Conceptual design of a bunch compressor system, and a chicane system for tuning the beam path length, compatible with multi-TeV operation.
Inclusion of spin in the simulation code GUINEA-PIG, and benchmarking of physics processes.
Evaluate (model) the performance of various post-LINAC collimation systems for given halo models, and evaluate the impact on the detector. Investigate the impact of luminosity tuning and errors on background performance.
Identification of key failure modes, and evaluation of their impact on the machine design.
Develop and optimise beam-based alignment algorithms and feedback systems to optimise the uminosity performance in the bunch compressor, main linac and beam delivery systems.
Conceptual design of a post-collision extraction lines; studies on the feasibility of post-collision diagnostics.

**Description of the sub-tasks**
Task ID	Contact Persons	Task Reporter	Task	Description
BDCS	M. Pedrozzi (PSI)	M. Pedrozzi	Bunch Compression Design	conceptual design of bunch compression system suitable for multi-TeV colliders, conceptual design of path length tuning chicane, basic parameter optimisation, performance simulation
PCDL	V.Ziemann (Uppsala) Ph. Bambade (Orsay)	V. Ziemann	Post-Collision Diagnostics Lattice	tracking simulations with emphasis on location of possible post- IP diagnostics, evaluation of physics potential of post-IP diagnostics, design of extraction line for multi-TeV collider
BBSIM	Ph. Bambade (Orsay) D. Schulte (CERN)	Ph. Bambade	Beam-Beam Simulation Code Development	benchmarking of physics processes in GUINEA-PIG against known and trusted physics generators, implementation of spin transport into GUINEA-PIG
HTGEN	H. Burkhardt (CERN) L. Neukermans (CERN)	H. Burkhardt	Halo and Tail Generation	study of potential sources of halo and tail generation in the LET, development of analytical models of halo, estimates of halo population, development of computer models for halo/ tail generation, simulation studies of halo/tail generation, explore possibilities for benchmarking
COLSIM	N. Walker (DESY) R. Barlow (UMA) G. Blair (RHUL) D. Schulte (CERN) A. Faus-Golfe (Valencia)	G.Blair	Collimation Simulations	simulation of post-linac beam halo collimation, estimation of collimator efficiency, optimisation of collimation system, simulations of muon and neutron production in collimator sections, estimates of impact of physics detector performance, studies of muon and neutron production, impact of luminosity tuning on halo collimation efficiency;
FMSIM	N. Walker (DESY) D. Schulte (CERN)	N. Walker	Failure Mode & Effect Simulations	determination of set of key failure modes (FM), simulation of FMs using sophisticated ILC modelling codes, evaluation of impact of FMs on accelerator performance / design, specific attention to BDS spoiler protection
LAST	Ph. Burrows (QMUL) N. Walker (DESY) D. Schulte (CERN)	Ph. Burrows	Luminosity and Alignment Studies	development of sophisticated models of the ILC from DR to IP, further development of beam-based alignment algorithms, simulations of algorithms with relevant machine imperfections, impact of upstream on downstream tuning, identify / specify diagnostics requirements, understand tuning time-scales, simulations of beam-base feedback systems in the presence of time-dependent environmental effects (e.g. ground motion), studies of intra-train and repetition rate based feedback, beambeam feedback, fast luminosity feedback, interaction of feedback systems, optimisation of stabilisation algorithms and number of feedback stations

Figure 1. Development of the electron and positron distributions during the collision at the ILC IP.

**Contacts**
WP Coordinator	e-mail
Daniel Schulte, CERN	daniel.schulte@cern.ch

List of items:

Workplan Drafts Repository

Agenda and Minutes of the ILPS Phone Meetings