SLAC, Menlo Park, California
IHEP Beijing, Beijing
LAL, Orsay
IN2P3-LAPP, Annecy-le-Vieux
ICEPP, Tokyo
University of Tokyo, Tokyo
KEK, Ibaraki
CERN, Geneva
The primary aim of the ATF2 research accelerator is to test a scaled version of the final focus optics planned for use in next-generation linear lepton colliders. ATF2 consists of a 1.3 GeV linac, damping ring providing low-emittance electron beams (<12pm in the vertical plane), extraction line and final focus optics. The design details of the final focus optics and implementation at ATF2 are presented elsewhere* . The ATF2 accelerator is currently being commissioned, with a staged approach to achieving the design IP spot size. It is expected that as we implement more demanding optics and reduce the vertical beta function at the IP, the tuning becomes more difficult and takes longer. We present here a description of the implementation of the overall tuning algorithm and describe operational experiences and performances
* Beam-Based Alignment, Tuning and Beam Dynamics Studies for the ATF2 Extraction Line and Final Focus System. Glen R. White , S. Molloy, M. Woodley, (SLAC). EPAC08-MOPP039, SLAC-PUB-13303.
KEK, Ibaraki
The beam extraction experiment using the strip-line kicker has been carried out at KEK-ATF. The specification of the International linear collider (ILC) is that the long bunch train (1320 - 5120 bunches), which has the bunch spacing of 189 - 480ns, is compressed to 3 or 6ns bunch spacing into the DR, and again decompressed from the DR. The kicker manipulates the changes of the bunch spacing. The kicker requires a fast rise/fall time (3 or 6ns) and a high repetition rate (3 or 6MHz). A multiple strip-line kicker system is the most promising candidate to realize the specification for the ILC*. The beam extraction experiment at KEK-ATF** using proto-type of the strip-line kicker was done by following parameters, up to 30 bunches of the multi-bunch in the DR, which has 5.6ns bunch spacing, are extracted bunch-by-bunch with 308ns interval to the extraction line. The stored multi-bunch was extracted successfully. The detail of the experiment and the result are reported.
* T. Naito et. al., Proc. of PAC07, pp2772-2274.
** T. Naito et. al., Proc. of EPAC08, pp601-603.
LAL, Orsay
KEK, Ibaraki
SLAC, Menlo Park, California
The purpose of ATF2 is to deliver a beam with stable very small spotsizes as required for future linear colliders such as ILC or CLIC. To achieve that, precise controls of the aberrations such as dispersion and coupling are necessary. Theoretically, the complete reconstruction of the beam matrix is possible from the measurements of horizontal, vertical and tilted beam sizes, combining skew quadrupole scans at several wire-scanner positions. Such measurements were performed in the extraction line of ATF2 in May 2009. We present analysis results attempting to resolve the 4X4 beam matrix and discuss the experimental limitations of 4D emittance measurements with wire scanners.
CERN, Geneva
LAL, Orsay
KEK, Ibaraki
BNL, Upton, Long Island, New York
SLAC, Menlo Park, California
The current ATF2 Ultra-Low beta proposal was designed to achieve 20nm vertical IP beam size without considering the multipolar components of the FD magnets. In this paper we describe different scenarios that avoid the detrimental effect of these multipolar errors in the FD. The simplest approach consists in modifying the optics but other solutions are studied as the introduction of new higher order magnets or the replacement of the FD with SC technology. The practical aspects of such an upgrade are the tuning performance and the compatibility with existing devices and instrumentation. These are fully addressed in the paper.
BNL, Upton, Long Island, New York
LAL, Orsay
IN2P3-LAPP, Annecy-le-Vieux
OXFORDphysics, Oxford, Oxon
CERN, Geneva
KEK, Ibaraki
SLAC, Menlo Park, California
The KEK ATF2 facility, with a well instrumented beam line and Final Focus (FF), is a proving ground for linear collider (LC) technology to demonstrate the extreme beam demagnification and spot stability needed for a LC FF*. ATF2 uses water cooled magnets but the baseline ILC calls for a superconducting FF**. Thus we plan to replace some ATF2 FF magnets with superconducting ones made via direct wind construction as planned for the ILC. With no cryogenic supply at ATF2, we look to cool magnets and current leads with a few cryocoolers. ATF2 FF coil winding is underway at BNL and production warm magnetic measurements indicate good field quality. Having FF magnets with larger aperture and better field quality than present FF might allow reducing the beta function at the FF for study of focusing regimes relevant to CLIC. Our ATF2 magnet cryostat will have laser view ports for cold mass movement measurement and FF support and stabilization requirements under study. We plan to make stability measurements at BNL and KEK to relate ATF2 FF magnet performance to that of a full length ILC R&D prototype at BNL. We want to be able to predict LC FF performance with confidence.
* ATF2 proposal, volumes 1 and 2 at http://lcdev.kek.jp/ILC-AsiaWG/WG4notes/atf2/proposal/index.html
** International Linear Collider Reference Design Report, ILC-REPORT-2007-001, August 2007.