Welcome to Jim Crittenden's Home Page

E-mail: crittenden@cornell.edu


Office Home
Wilson Synchrotron Laboratory 112 Larchmont Drive
Cornell Laboratory for Accelerator-based Sciences and Education Trumansburg, New York 14886
Cornell University Tel: (607) 422-0089
Ithaca, New York 14853-8001
Tel: (607) 255-4882

Curriculum vitae as of October, 2024 (pdf) and photos (2001,2005,2015,2018)

The Electron-Positron Storage Ring CESR at Cornell University

On October 1, 2001, I joined the Operations Group at CESR (click here for a tour). CESR has been in operation for over 44 years at the Wilson Synchrotron Laboratory, part of the Cornell Laboratory for Accelerator-based Sciences at Cornell University, which conducts research in photon science, accelerator physics, and particle physics and astrophysics.

A persuasive argument in favor of a role for elementary-particle experimentalists in future accelerator design and development may be found in an article by Maury Tigner published in the January, 2001 issue of Physics Today.

My arrival coincided with a new era in CESR's history of providing colliding beams of electrons and positrons for high-statistics studies of electron-positron interactions. Beginning in the Fall of 2001, the beam energies were chosen such as to allow high-precision studies of decays of the Upsilon family of resonances. Beginning in 2004, CESR-c project, described in detail here, made it possible to extend these high-statistics studies to the physics of bound states of charm quarks. Operation of CESR as a charm factory began following accelerator R&D and installation work, continuing into 2008.

During 2008 and 2009 the CESR Test Accelerator project (CESRTA) undertook the conversion of the CESR ring to a test facility for future accelerator projects such as the International Linear Collider. An extensive measurement program on electron cloud buildup, instabilities, mitigation techniques and on low-emittance optics development was performed through 2017, entailing significant progress in validating ever-more sophisticated modeling efforts to which I contributed.

In addition to operation as an e+e- collider, the CESR ring serves to provide photon beams for X-ray science under the aegis of the Cornell High-Energy Synchrotron Source (CHESS) laboratory. My work includes contributions to the responsibility of the Operations Group for maintaining high-quality X-ray beams, including machine studies experiments, performance modeling, and upgrades. As of this writing, one-sixth of the ring is being replaced with optics consisting of six double-bend achromats and undulators, resulting in an improvement in emittance by a factor of four. Since this single-beam operation at 6.0 GeV will use a positron beam, an important contribution to performance limits will be electron cloud buildup, so the past decade of CESRTA measurements and model validation is serving the purpose of estimating the limits for various bunch train configurations.

In 2016, the Wilson Lab undertook in collaboration with the Brookhaven National lab the design, construction and commissioning of the Cornell-Brookhaven ERL Test Accelerator CBETA (APS Physics online magazine, CERN Courier article), a four-pass 150-MeV electron accelerator with energy recovery and a fixed-field alternating-gradient return loop made up of permanent-magnet quadrupoles. I have contributed magnet design, layout and optics design efforts to this three-year project. I participated in the commissioning of Fractional Arc Test in May, 2018, when the first beam through the first girder of the return loop was achieved. The first 42 MeV beam through the return loop with energy recovery on the second pass through the linac was achieved in early summer 2019. Multiple pass operation began during the Fall of 2019. Four-pass operation with energy recovery was achieved on December 24, 2019.

Following up on the magnet design work for CBETA, I began an in-depth study of the accuracy of finite-element models of static magnetic fields, culminating in the publication Nucl. Instrum. Meth. A1005, 165370 (2021)

In 2021, I began developing a series of experimental data sets using CESR positron beams with the goal of determining the accuracy limits in the measurement of horizontal beam size, exploiting the symmetry characteristics of sexupole magnetic fields. This work included the precise measurement of the CESR sextupole magnet positions, as well as of their field calibration constants. This work is described in detail in the arXiv preprint 2409.19728 of 29 September 2024.

I retired from Cornell University on March 31, 2024.

Most recent Projects


  • CESR-c Lattice Design Meetings October/November 2006

  • CESR Lattice Characterization Calculations



  • Presentation on Beam Current Limitations and Duty Cycle Considerations (html,ps)
    to the CESR-c MiniMAC workshop held at Cornell University July 22-23, 2005


  • Design of 1-m-long solenoid magnets for new CLEO-solenoid compensating CESR optics



  • Design of a Large-Aperture Quadrupole Magnet for the Fast Luminosity Monitor Project


  • Synchrotron-light-based Measurement of CESR Beam Size


  • CESR Wiggler Magnet Field Calculations



  • Dismantling and Re-installation of the Interaction Region Beamline Components during the 2003 March-July shutdown



    Related Publications



    Related Talks