Cornell University, Department of Physics, Ithaca, New York
CLASSE, Ithaca
University of Minnesota, Minneapolis, Minnesota
CESR-LEPP, Ithaca, New York
Technion, Haifa
In April 2008, we propose to begin operation of the Cornell Electron Storage Ring (CESR) as a test accelerator, CesrTA, for International Linear Collider (ILC) damping ring research. Utilizing 12 damping wigglers, the baseline CesrTA lattice at 2.0 GeV will offer a natural geometric emittance of 2.25 nm. An experimental program has been laid out which focuses on several key areas of damping rings R&D. First we will test vacuum chamber designs to suppress electron cloud growth in the wiggler magnets. Secondly, we will develop correction, tuning and emittance monitoring strategies to achieve vertical emittances of a few picometers. As part of this effort we will validate alignment and survey techniques being developed by the Linear Collider Alignment and Survey group (LiCAS) for curved tunnel applications. After achieving ultra-low emittance, we intend to explore the impact of the electron cloud, the fast ion instability and other beam dynamics effects on ultra-low emittance beams. Finally, we plan to test various technical systems required for the ILC damping rings. This paper provides an update on conceptual design issues for CesrTA and describes the experimental program in detail.
Cornell University, Department of Physics, Ithaca, New York
CLASSE, Ithaca
The ILC damping rings require wiggler magnets with large physical aperture and with excellent field quality to maintain the dynamic aperture of the rings. We consider two possible designs derived from the wigglers presently in operation at the Cornell Electron Storage Ring. Design optimization has been performed based on detailed tracking calculations of dynamic aperture and tune footprint in a full model of the damping ring. Results of finite-element modeling, transfer functions, and the accuracy of analytic models of the wiggler field will be discussed.
Alfred University, Alfred, New York
CESR-LEPP, Ithaca, New York
Presently, CESR is operated at two different beam energies, low energy (E=2GeV) for high energy physics (CESR-c), and high energy (E=5.3GeV) for synchrotron radiation production (CHESS). The electron and positron bunches vertical dynamics at these two energies are vastly different, in part due to the change in the pretzel orbit, the presence of wiggler magnets at low energy, and synchrotron radiation power at two vastly different energies. Using the 32 channel photomultiplier array*, we measured the vertical beam dynamics on a turn-by-turn basis during CHESS and CESR-c operation as well as dedicated machine studies time. For these studies we quantify the electron cloud effects such as vertical tune shift and vertical beam size blow-up along the electron and positron trains at these two vastly different beam energies. In addition, the turn-by-turn capability of the PMT array allows us to study the vertical bunch dynamics over 10k turns.
* Design and Implementation of an Electron and Positron Multibunch Turn-by-Turn Vertical Beam Profile Monitor in CESR-PAC2007 proceedings
CESR-LEPP, Ithaca, New York
Alfred University, Alfred, New York
CLASSE, Ithaca
CMU, Pittsburgh, Pennsylvania
A fast vertical beam profile monitor has been implemented at the Cornell Electron Storage Ring (CESR). Readout is based on the Hamamatsu H7260K multianode photomultiplier. This device has a 32 channel linear anode array with 1 mm channel pitch and sub-nanosecond rise time. It provides the ability to probe individual electron and position bunches which are separated by 14 ns within the trains in CESR. A custom 72 MHz digitizer unit allows synchronous multibunch and turn-by-turn data acquisition. An on-board digital signal processor provides local data processing capability. This system provides the capability to probe a range of single bunch and multibunch beam dynamics issues as well as machine stability issues. In this paper we describe the profile monitor hardware, data acquisition system, calibration of the profile monitor, and data analysis software.
Fermilab, Batavia, Illinois
Cockcroft Institute, Warrington, Cheshire
CLASSE, Ithaca
BNL, Upton, Long Island, New York