Abstracts Brochure - CERN

MOPLS076
MOPLS077
MOPLS078
26-Jun-06 16:00 - 18:00 MOPLS — Poster Session
For a beam energy of 500GeV and a crossing angle of 20mrad, the required crab kick is about 19.5MV at 1.3GHz and
6.5MV at 3.9GHz. Cavities are needed on both beams and are likely to be positioned about 12m before the IP. Any RF
phase error between the bunch and the cavity leads to a deflection of the bunch in addition to a rotation of the bunch.
Any differential phase error between the cavities leads to differing deflections and consequential loss in luminosity.
Collaborative work with FNAL, being undertaken to develop a variant of their 3.9GHz CKM cavity optimised for
an ILC solution, is described. Current analysis favours a solution with four nine-cell cavities on each beam. It is
anticipated that the cavities will be run CW and driven from small Klystron/s (< 5kW) or solid state amplifiers.*
*We would like to thank Chris Adolphsen, SLAC, for his help in technical discussions, which were greatly appreciated.
The Stimulated Breit-Wheeler Process as a Source of Background e + e − Pairs at the International
Linear Collider
The bunch fields at the interaction point of
A.F. Hartin (Queen Mary University of London)
the ILC have a dominant effect on background
pair production. The Breit-Wheeler,
Bethe-Heitler and Landau-Lifshitz processes have all been studied in detail. The number of background pairs per
bunch crossing due to these processes is well known. However the effect of the bunch fields on the Breit-Wheeler
process has not been calculated. This Stimulated Breit-Wheeler (or Stimulated Two Photon Pair Production) process,
contains cross-section resonances, and significant numbers of background pairs may result from it. Presented here
is a theoretical calculation and numerical investigation of the Stimulated Breit-Wheeler cross-section. This is a full
QED calculation, and the external field is treated with the semi-classical approximation. The form of the bunch field
considered is a plane wave, constant crossed electromagnetic field. Calculation of resonances involved inclusion of
the Electron Self Energy in the external field. The end goal of the numerical investigation is the characteristics of new
background pairs that can be expected at the ILC.
The 2mrad Crossing Angle Interaction Region and Extraction Line
R. Appleby (UMAN) D.A.-K. Angal-Kalinin (CCLRC/DL/ASTeC)
P. Bambade (LAL) K. C. Moffeit, Y. Nosochkov, A. Seryi, C.M.
Spencer (SLAC) B. Parker (BNL)
130
The complete optics design for the 2mrad
crossing angle interaction region and extraction
line was presented at Snowmass 2005.
Since this time, the design task force has been
working on developing and improving the
layout. The work has focused on optimising the final doublet (including by using higher gradient magnet materials),
on reducing the power losses resulting from the disrupted beam transport and on evaluating backgrounds. In this
note, the most recent status of the 2mrad layout and the corresponding performance are presented.
Benchmarking and Tracking of BDSIM/DIMAD Using the ILC Extraction Lines
R. Appleby (UMAN) P. Bambade, X. Dadoun (LAL) A. Ferrari (UU/
ISV)
The study of beam transport is of central importance
to the design and performance assessment
of modern particle accelerators. In
this work, we benchmark two contemporary
codes - DIMAD and BDSIM, the latter being a relatively new tracking code and built within the framework of
GEANT4. We consider both the 20mrad and 2mrad extraction lines of the International Linear Collider and perform