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B.A., 1976, University of Pennsylvania. Ph.D., 1983, University of Michigan. Research Associate, Laboratory of Nuclear Studies, Cornell University, 1983-86; Assistant Professor, Physics, Cornell University, 1986-92; Associate Professor, Physics, Cornell University, 1992-98; Professor, Physics, Cornell University, 1998-present. Fellow, American Physical Society, Boyce D. McDaniel Chair, 2000. Director of Accelerator Physics of LEPP, 1994-present. Board of Governors, United States Particle Accelerator School, 1998; Program Committee, US Particle Accelerator School, 1999. PEPII Machine Advisory Committee, 2003. Brookhaven Science Associates Science and Technology Steering Committee, 2004. Accelerator Systems Advisory Committee NSLS II, 2006.

Research Areas

Lepton colliders; beam-beam interaction; particle beam optics; non-linear dynamics of particle beams; transverse coupling in beams; resonance phenomena; beam diagnostic instrumentation; RF superconductivity; circular colliders; electron cloud

Current Research

The International Linear Collider is a proposed new electron-positron collider that would allow for the exploration of energy regions beyond the reach of today's accelerators. In the debris of the very high energy collisions, 1 TeV in the center of mass, we will look for, among many other thinks, the identity of dark matter and the existence of extra dimensions.

In  the ILC's design, two facing linear accelerators, each 20 kilometers long, hurl beams  of electrons and positrons toward each other at nearly the speed of light. Each beam contains ten billion electrons or positrons compressed to a minuscule three-nanometer thickness. As the particles speed down the collider, superconducting accelerating cavities give them more and more energy. They meet in an intense crossfire of collisions.

In the linear collider, positrons are produced by pair production in the collision of photons on a high Z target. The phase space volume of the hot positrons that emerge from the target is very large. In order to achieve an adequate collision rate of the electron and positron beams at the interaction point, the phase space volume (emittance) of the positrons must be reduced by nearly three orders of magnitude. The beams are cooled in damping rings.

The current density of the very low emittance damped bunches will be greater than has ever been achieved in a storage ring. That density will be limited by electron cloud effects and intra beam scattering. In order to explore the relevant beam physics well in advance of the completion of the design of the ILC damping rings, the Cornell Electron Storage Ring (CESR) was reconfigured during the summer of 2008 as a linear collider damping ring test accelerator (CesrTA). During the approximately 100 days of machine time dedicated to the CesrTA project this year, we are developing and testing low emittance tuning techniques. We have built and are presently testing an xray beam size monitor. We are measuring the evolution of the electron cloud with the retarding field analyzers installed last summer and the dynamical effects of that cloud on the circulating beam of positrons. We are deploying high precision beam position monitor electronics and during the next two years we plan to test various electron cloud mitigation techniques.

Graduate students Jim Shanks and Joe Calvey are involved in the development and study of low emittance tuning methods and instrumentation for measuring electron cloud density and energy spectrum. Walter Hopkins and Nic Eggert are building the xray beam size monitor. Jesse Livezay is an undegrad and he is writing data acquisition software and modeling electron cloud detector response. Dane Gonella is an REU student studying touschek and intra-beam scattering. The research associates in the CesrTA group are Mark Palmer, David Sagan, Jim Crittenden, Sasha Temnykh, Shlomo Greenwald, Yulin Li, Robert Meller, and David Rice. All of us spend many hours in the CESR control room during CesrTA machine studies periods. CesrTA is an international collaboration. Institutions from around the world, including KEK(Japan), SLAC(Stanford), LBNL(Berkeley), Fermi National Accelerator Lab, Brookhaven National Lab, Cockroft Institute (Great Britain), and CERN(Switzerland) are contributing equipment, numerical simulations and help executing and analyzing experiments.