• Theoretical Condensed-Matter Physics
• Theoretical Elementary Particle Physics
• Astrophysics and General Relativity
• Experimental Elementary Particle Physics
• Accelerator Physics
• Experimental Condensed-Matter Physics
• Biological Physics
• Multidisciplinary Research
• Major Research Facilities
• Resources for Researchers

Diplom, 1991, Darmstadt University of Technology, Germany. M.S., 1992, and Ph.D., 1994, as NSCL Fellow and Natural Science Fellow, Michigan State University. Dr. habil. (doctor habilitatus), 2000, Darmstadt University of Technology. Research Associate, Deutsches Elektornen-Synchrotron (DESY), Hamburg, Germany, 1994-1996. Faculty, Darmstadt University of Technology, 1996-1998. Accelerator Physicist, DESY, 1998-2002. Associate Professor, Cornell University, 2002-2008. Professor, Cornell University, 2009-present. Fellow, German National Merrit Foundation.

Research Areas
Physics of Beams; Accelerator Technology

Current Research

The Physics of Beams is the study of accelerated beams as a special state of matter. It has many applications in particle accelerators, spectrometers, electron microscopes, and lithographic devices. These instruments have become so complex that an empirical approach to properties of the particle beams is by no means sufficient and a detailed theoretical understanding is necessary. Historically it has proved fruitful that studies in beam physics have been performed in the context of projects that developed or built one of these instruments, and I have worked on several such projects, on the 4 mile circular accelerator HERA in Hamburg, where I contributed to the understanding of the non-linear dynamics and longterm stability of the stored particles, of polarization dynamics, and of space charge forces acting from one particle beam to another. I am coordinating the accelerator science work for the Energy Recovery Linear Accelerator (ERL) Project at Cornell where my interests concern nonlinear beam dynamics, multi bunch instabilities, space charge within a tightly focused beam, the creation of synchrotron light, and the back-reaction of coherently emitted light on the beam. This accelerator will constitute a novel x-ray light source with beams significantly better than those of the world's most advanced facilities. X-ray beams from charged particle accelerators have become an essential tool in today's investigation of all types of materials, from airplane wings to cell membranes and from pollutants in leaves to matter under earth-core pressures. The development of the ERL, envisioned and invented at Cornell, that provides more brilliant beams in shorter pulses will move such investigations to new frontiers.

Accelerator Technology describes the technology used to accelerate large currents of tightly focused beams to high energies. These beams are then used to study elementary particles, to produce synchrotron light for analysis in biophysics, in crystalography, in surface physics, or in the material sciences, for cancer therapy, and for a variety of other applications. Studies with synchrotron light are currently performed by CHESS at Cornell. The technology involved in accelerators is very rich and I am currently mostly interested in the technology required for the Cornell ERL where the energy of accelerated particles is recovered in superconducting cavities in order to accelerate new particles. These particles are produced in a photo cathode electron gun which involves a very complex system of lasers. Subsequently they are accelerated in a superconducting radio-frequency (SRF) linac. I am head of Cornell's SRF laboratory, which is involved not only in SRF for ERLs, but also for high-energy elementary-particle accelerators like the ILC, a muon collider, and Fermilab's Project-X.

Postdoc
Christopher Mayes (Linear and Nonlinear Particle Optics, Coherent Synchrotron Radiation, ERL layout)

Graduate Students 
Michael Ehrlichman (Ion instabilities, beam-ion measurement, intra-beam scattering)

Further information can be obtained by contacting research associates and graduate students at Wilson Laboratory and at http://www.lns.cornell.edu/accelphys/ and http://www.lepp.cornell.edu/Research/AP/SRF/WebHome.html .

Graduate and undergraduate students interested in beam physics and the application of particle accelerators are encouraged to join this group. There are many opportunities for student involvement.

Spotlight

Michael Ehrlichman, graduate student, is working in Professor Georg Hoffstaetter’s group researching the effect of ionized residual gas on particle accelerator beams.  Residual gas molecules ionized by charged particle beams can become trapped in the potential well of the beam.  These trapped ions exert a nonlinear focusing force on the beam that can reduce beam quality.  The ions can also undergo coupled oscillations with the beam.  These coupled oscillations can become unstable and increase the effective dimensions of the beam or ...
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