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My Publications

My scientific life:

Curriculum Vitae

Books and Journals

• Physical Review Special Topics - Accelerators and Beams,
  Editors: Frank Zimmermann, Georg Hoffstaetter, Brant Johnson (2007 - today)
• High Energy Polarized Proton Beams; A Modern View,
  G. H. Hoffstaetter, Springer Publishing, Tracts in Modern Physics (2006), ISBN 0-387-34679-1
• Focus on Accelerator and Beam Physics (with 20 scientific articles),
  Editors: Georg H. Hoffstaetter, Kwang-Je Kim, Ferdinand Willeke, New Journal of Physics 8 (2006)
• High Energy Polarized Proton Beams; A Modern View,
  G. H. Hoffstaetter, Springer Publishing, Tracts in Modern Physics (2006), ISBN 0-387-34679-1
  based on the habilitation thesis "Aspects of the Invariant Spin Field for High Energy Polarized Proton Beams",
  G. H. Hoffstaetter, Darmstadt University of Technology (January 2000)

Accelerator physics in an Energy Recovery Linac (ERL) at CESR

While the emittances of an electron beam can be smaller in a linear accelerator than in a ring-based synchrotron radiation source, the beam power in a ring can be much larger since the high energy electrons create a large current while they are used over and over again on each revolution. In order to create similar beam powers in a linear accelerator, exorbitant electrical energy would be required, which would be consumed and dumped at the end of the accelerator. Energy Recovery Linacs (ERLs) might lead out of this dilemma. They recover the energy of the spent electron beam in superconducting cavities and use it to accelerate subsequent electron bunches. Cornell plans to build a prototype facility that tests several critical accelerator physics issues before a large scale x-ray facility based on an ERL can be proposed. After successful test an ERL addition to the CESR accelerator at Cornell University should create an exceptional X-ray facility.

In the Press

• The Sound of Accelerating Cavities ,
  Report in ILC NewsLine with comments from G.H. Hoffstaetter (21 April 2011)
• Cornell makes progress on Energy Recovery Linac ,
  Interview of ilc NewsLine with G.H. Hoffstaetter (27 January 2011)
• Accelerator physicists to attend international ERL workshop at Cornell,
  Cornell Chronicle on ERL workshop, who's organizing committee is chaird by G.H. Hoffstaetter (06 June 2009)
• Faculty Senate votes for no classes on Labor Day,
  Cornell Chronicle on a resolution in the facutly senate, introduced by EPC Chair G.H. Hoffstaetter (16 April 2009)
• Inaugural research forum focuses on next-generation accelerator project,
  Cornell Chronicle on a talk by G.H. Hoffstaetter (7 August 2008)
• Time to recover Cornell University is testing a prototype injector for an Energy Recovery Linac ,
  Interview of ilc NewsLine with G.H. Hoffstaetter (31 July 2008)

Publications

• Coherent Synchrotron Radiation Simulations for the Cornell Energy Recovery Linac,
  C.E. Mayes, G.H. Hoffstaetter, Proceedings IPAC10, Kyoto/J (2010)
• Cornell Energy Recovery Linac Lattice and Layout,
  C.E. Mayes, G.H. Hoffstaetter, Proceedings IPAC10, Kyoto/J (2010)
• An extension of Cornell's Energy Recovery Linac for compressed high-charge bunches,
  F.A. Laham, G.H. Hoffstaetter, C.E. Mayes, J.R. Thompson, Proceedings IPAC10, Kyoto/J (2010)
• Beam pipe HOM absorber for 750MHz RF Cavities,
  M.L. Neubauer, A. Dudas, R. Sah, G.H. Hoffstaetter, M. Liepe, H. Padamsee, V. Shemelin, Proceedings IPAC10, Kyoto/J (2010)
• Latest Results and Test Plans from the 100mA Cornell ERL injector SCRF Cryomodule,
  M. Liepe, S.A. Belomestnykh, E.P. Chojnacki, Z.A. Conway, G.H. Hoffstaetter, R.P.K. Kaplan, S.E. Posen, P. Quigley, J. Sears, V.D. Shemelin, V. Veshcherevich, Proceedings IPAC10, Kyoto/J (2010)
• The Cornell Energy Recovery Linac: update on a future source of coherent hard x-rays,
  Don Bilderback, Bruce Dunham, Georg Hoffstaetter, Alexander Temnykh, Sol Gruner, CHESS News Magazine (2009)
• ILC testing program at Cornell University,
  Z.A. Conway, E.P. Chojnacki, D.L. Hartill, G.H. Hoffstaetter, M.U. Liepe, H.S. Padamsee, A.S. Romanenko, J.O. Sears, Proceedings SRF09, Berlin/FRG (2009)
• Assembly preparations for the international ERL cryomodule at Daresbury laboratory,
  P. A. McIntosh, R. Bate, C. D. Beard, M. A. Cordwell, D. M. Dykes, S. M. Pattalwar and J. Strachan, S. Belomestnykh, Z. Conway, G. Hoffstaetter, M. Liepe, H. Padamsee, P. Quigley, J. Sears, V. Shemelin and V. Veshcherevich, D. Proch and J. Sekutowicz, A. Baechner, F. Gabriel and P. Michel, J. N. Corlett, D. Li and S. Lidia,T. Kimura and T. I. Smith, Proceedings SRF09, Berlin/FRG (2009)
• The Cornell Energy Recovery Linac: update on a future source of coherent hard x-rays,
  D. Bilderback, B. Dunham, G.H. Hoffstaetter, A. Temnykh, S. Gruner, Synchrotron Radiation News (2009)
• Developments for Cornell's x-ray ERL,
  J.A. Crittenden, I.V. Bazarov, S.A. Belomestnykh, D.H. Bilderback, M.G. Billing, J.D. Brock, E.P. Chojnacki, B.M. Dunham, M.P. Ehrlichman, M.J. Forster, S.M. Gruner, G.H. Hoffstaetter, C.J. Johnstone, Y.Li, M.U. Liepe, C.E. Mayes, A.A. Mikhailichenko, H.S. Padamsee, S.B. Peck, D.C. Sagan, V.D. Shemelin, A. Temnykh, M. Tigner, V. Veshcherevich, Proceedings PAC09, Vancouver/CA (2009)
• Collimating Touschek particles in an Energy Recovery Linear accelerator,
  M.P. Ehrlichman, G.H. Hoffstaetter, Proceedings PAC09, Vancouver/CA (2009)
• Exact CSR Wakes for the 1-D Model,
  C.E. Mayes, G.H. Hoffstaetter, Proceedings PAC09, Vancouver/CA (2009)
• Initial beam results from the Cornell high-current ERL injector prototype,
  I. Bazarov, S. Belomestnykh, E. Chojnacki, J. Dobbins, B. Dunham, R. Ehrlich, M. Forster, C.I. Gulliford, G. Hoffstaetter, H. Li, Y. Li, M. Liepe, X. Liu, F. Loehl, D. Ouzounov, H. Padamsee, D. Gulliford, D. Rice, V. Shemelin, E. Smith, K. Smolenski, M. Tigner, V. Veshcherevich, Proceedings PAC09, Vancouver/CA (2009)
• Design of an ERL linac cryomodule,
  E. Chojnacki, S. Belomestnykh, S. Chapman, R. Ehrlich, G. Hoffstaetter, M. Liepe, H. Padamsee, J. Sears, E. Smith, V. Veshcherevich, Proceedings PAC09, Vancouver/CA (2009)
• Extended 1D method for Coherent Synchrotron Radiation including Shielding,
  D.C. Sagan, G.H. Hoffstaetter, C.E. Mayes, U. Sae-Ueng, Physical Review ST-AB 12, 040703 (2009)
• Exact 1D model for coherent synchrotron radiation with shielding and bunch compression,
  C.E. Mayes, G.H. Hoffstaetter, Physical Review ST-AB 12, 024401 (2009)
• Wake-field compensation in Energy Recovery Linacs,
  G.H. Hoffstaetter, M.G. Billing, Y.H. Lau, Proceedings EPAC08, Genoa/IT (2008)
• Intra Beam Scattering in Linear Accelerators, especially ERLs,
  G.H. Hoffstaetter, M.P. Ehrlichman, A.B. Temnykh, Proceedings EPAC08, Genoa/IT (2008)
• CSR including Shielding in the Beam Dynamics code Bmad,
  David C. Sagan, G.H. Hoffstaetter, C.E. Mayes, U. Sae-Ueng, Proceedings EPAC08, Genoa/IT (2008)
• Challenges for Beams in an ERL Extension to CESR,
  G.H. Hoffstaetter, I.V. Bazarov, D.H. Bilderback, M.G. Billing, G.W. Codner, J.A. Crittenden, B.M. Dunham, M.P. Ehrlichman, K.D. Finkelstein, M.J. Forster, S. Greenwald, S.M. Gruner, V.O. Kostroun, Y. Li, M.U. Liepe, C.E. Mayes, S.B. Peck, D.C. Sagan, Ch. Spethmann, A.B. Temnykh, M. Tigner, Y. Xie, Proceedings EPAC08, Genoa/IT (2008)
• Beam losses due to intra-beam and residual gas scattering for Corenll's Energy Recovery Linac,
  A.B. Temnykh, M.P. Ehrlichman, G.H. Hoffstaetter, Proceedings EPAC Genoa/IT (2008)
• Compensation of wake-field-driven energy spread in Energy Recovery Linacs,
  G.H. Hoffstaetter, Y.H. Lau, Physical Review ST-AB 11, 070701 (2008)
• Equilibrium ion distribution in the presence of clearing electrodes and its influence on electron dynamics,
  G.H. Hoffstaetter, C. Spethmann, Physical Review ST-AB 11, 014001 (2008)
• Particle Orbit Correction in an Energy Recovery Linac,
  C. Song, G. Hoffstaetter, Cornell-Report-ERL-07-04 (2007)
• Beam-breakup simulations for the Cornell x-ray ERL,
  C. Song, G. Hoffstaetter, Proceedings PAC07, Albuquerque/NM (2007)
• Controlling coupler-kick emittance growth in the Cornell ERL main linac,
  G.H. Hoffstaetter, B. Buckley, Proceedings PAC07, Albuquerque/NM (2007)
• Equilibrium ion distribution in the presence of clearing electrodes and its influence on electron dynamics,
  G.H. Hoffstaetter, C. Spethmann, Proceedings PAC07, Albuquerque/NM (2007)
• Progress toward an ERL Extension to CESR,
  G.H. Hoffstaetter, I.V. Bazarov, D.H. Bilderback, J. Codner, B. Dunham, D. Dale, K. Finkelstein, M. Forster, S. Greenwald, S.M. Gruner, Y. Li, M. Liepe, C. Mayes, D. Sagan, C.K. Sinclair, C. Song, A. Temnykh, M. Tigner, Y. Xie, Proceedings PAC07, Albuquerque/NM (2007)
• Method of perturbative-PIC simulation for interactions between a particle bunch and its coherent synchrotron radiation,
  J. Shi, G.H. Hoffstaetter, Method of Perturbative-PIC Simulation for Interactions between a Particle Bunch and Its Coherent Synchrotron Radiation, Proceedings PAC07, Albuquerque/NM (2007)
• Transverse Emittance Dilution due to Coupler Kicks in Linear Accelerators,
  B. Buckley, G.H. Hoffstaetter, Physical Review ST-AB 10, 111002 (2007)
• Recirculating BBU thresholds for polarized HOMs with optical coupling,
  G.H. Hoffstaetter, I.V. Bazarov, C. Song, Physical Review ST-AB 10, 044401 (2007)
• Transverse Quadrupole BBU Threshold Current in the Cornell X-ray ERL ,
  C. Song, G.H. Hoffstaetter, Report Cornell-ERL-07-10 (2007)
• Magnetic Field Error Sensitivity in an Energy Recovery Linac ,
  C. Song, G.H. Hoffstaetter, Report Cornell-ERL-07-03 (2007)
• Energy Recovery Linac - The future gets brighter,
  G.H. Hoffstaetter, Connecting with Cornell, Office of the Vice Provost for Research, Cornell University (Fall 2006)
• Longitudinal BBU Threshold Current in Recirculating Linacs ,
  C. Song, G.H. Hoffstaetter, Report Cornell-ERL-06-04 (2006)
• Experimental investigation of multibunch, multipass beam breakup in the Jefferson Laboratory Free Electron Laser Upgrade Driver ,
  D.R. Douglas, K.C. Jordan, L. Merminga, E.G. Pozdeyev, C.D. Tennant, H. Wang, T.I. Smith, S. Simrock, I.V. Bazarov, G.H. Hoffstaetter, Physical Review ST-AB 9, 064403 (2006)
• Emittance Dilution due to Transverse Coupler Kicks in the Cornell ERL,
  B. Buckley, J. Choi, G.H. Hoffstaetter, Report Cornell-ERL-06-02 (2006)
• Transverse Recirculating-BBU Threshold Current in the Cornell x-ray ERL,
  C. Song, G.H. Hoffstaetter, Report Cornell-ERL-06-01 (2006)
• Ion clearing in an ERL,
  G.H. Hoffstaetter, M.U. Liepe, Nuclear Instruments and Methods in Physics Research A 557, 205-212 (2006)
• Optics and Beam Transport in Energy Recovery Linacs ,
  G.H. Hoffstaetter, V. Litvinenko, H. Owen, Nuclear Instruments and Methods in Physics Research A 557, 345-353 (2006)
• Optics issues in ongoing ERL projects ,
  S. Smith, B.D. Muratori, H.I. Owen, G.H. Hoffstaetter et al., Nuclear Instruments and Methods in Physics Research A 557, 145-164 (2006)
• Impact of a future energy recovery linac x-ray source on nanoscale science,
  D. Bilderback, I.V. Bazarov, J.D. Brock, E. Fontes, S.M. Gruner, G.H. Hoffstaetter, A. Kaimirov, Q. Shen, CHESS News Magazine (2005)
• Characterization of CESR BPMs Using a BPM Test Stand,
  J. Urban, N. Iqbal, G.H. Hoffstaetter, M. Billing, Report Cornell-CBN-05-19 (2005)
• ERL upgrade of an existing X-ray facility: CHESS at CESR,
  G.H. Hoffstaetter, Report Cornell-ERL-05-08, this is a contribution to the following paper by S. Smith et al. (2005)
• Status of a Plan for an ERL Extension to CESR,
  G.H. Hoffstaetter, I.V. Bazarov, S. Belomestnykh, D.H. Bilderback, M.G. Billing, J.S-H. Choi, Z. Greenwald, S.M. Gruner, Y. Li, M. Liepe, H. Padamsee, D. Sagan, C.K. Sinclair, K.W. Smolenski, C. Song, R.M. Talman, M. Tigner, Proceedings PAC05, Knoxville/TN (2005)
• Experimental investigation of beam breakup in the Jefferson Laboratory 10kW FEL Upgrade,
  C. Tennant, D. Douglas, K. Jordan, L. Merminga, E. Pozdeyev, H. Wang, I.V. Bazarov, G.H. Hoffstaetter, C.K. Sinclair, S. Simrock, T.I. Smith, Proceedings PAC05, Knoxville/TN (2005)
• Orbit and Optics Improvement by Evaluating the Nonlinear BPM Response
  in the Cornell Electron Storage Ring,
  R.W. Helms, G.H. Hoffstaetter, Physical Review ST-AB 8, 062802 (2005)
• ERL upgrade of an existing X-ray facility: CHESS at CESR,
  G.H. Hoffstaetter, I.V. Bazarov, D. Bilderback, M. Billing, S. Gruner, M. Liepe, D. Sagan, C. Sinclair, K. Smolenski, R. Talman, M. Tigner, Report Cornell-ERL-04-5 and Proceedings EPAC04, Lucerne/CH (July 2004)
• Multi-pass beam-breakup: Theory and Calculation,
  I.V. Bazarov, G.H. Hoffstaetter, Report Cornell-ERL-04-7 and Proceedings EPAC04, Lucerne/CH (July 2004)
• Evaluation of Beam Position Monitors in the Nonlinear Regime,
  R.W. Helms, G.H. Hoffstaetter, Proceedings EPAC04, Lucerne/CH (July 2004)
• Results from Orbit and Optics Improvement by Evaluating the
  Nonlinear Beam Position Monitor Response in CESR,
  R.W. Helms, G.H. Hoffstaetter, Proceedings EPAC04, Lucerne/CH (July 2004)
• Reduction the synchrotron radiation on RF cavity surfaces in an Energy-Recovery Linac,
  G. H. Hoffstaetter, M. Liepe, T. Tanabe, Report Cornell-ERL-04-6 and Proceedings EPAC04, Lucerne/CH (July 2004)
• Beam-Breakup Instability Theory for Energy Recovery Linacs,
  G. H. Hoffstaetter, I. Bazarov, Physical Review ST-AB, Volume 7, 54401 (May 2004)
• Reduction of synchrotron radiation of RF cavity surfaces in the proposed Cornell Energy-Recovery Linac,
  G. H. Hoffstaetter, T. Tanabe, Report Cornell-ERL-04-2 (February 2004)
• Influence of undulators on nonlinear ERL optics,
  C. Koupparis, G. H. Hoffstaetter, Report Cornell-ERL-03-14 (August 2003)
• A Lattice for a 5GeV ERL in the CESR Tunnel,
  G. H. Hoffstaetter, I. Bazarov, D. Sagan, R. Talman, Report ERL03-13 and Proceedings of PAC'03, Portland/OR (May 2003)
• The Cornell ERL prototype project,
  G. H. Hoffstaetter, B. Barstow, I. Bazarov, S. Belomestnykh, D. Bilderback, S. Gruner, G. Krafft, M. Liepe, L. Merminga, H. Padamsee, D. Sagan, V. Shemelin, C. Sinclair, R. Talman, M. Tigner, V. Veshcherevich, Report ERL03-12 and Proceedings of PAC'03, Portland/OR (May 2003)
• Lattice options for a 5GeV light source at Cornell,
  I. Bazarov, G. H. Hoffstaetter, Report ERL03-10 and Proceedings of PAC'03, Portland/OR (May 2003)

Invited Conference Talks, Seminars, and Colloquia

• . Design considerations for x-ray ERLs, Workshop ERL09 (June 2009)
• . The Cornell ERL Program, Workshop ERL09 (June 2009)
• . Energy Recovery Linacs, Retirement Festivities for Director Eberhard Jaeschke (March 2009)
• . NSCL Physics Seminar (March 2009)
• ERL for the generation of VUV and X-ray photons. Photon workshop of the BESAC subcommittee 'Facing our energy challenges in a new era of science' (October 2008)
• . BESSY Physics Seminar (August 2008)
• An Energy Recovery Linac X-Ray Source at Cornell University. First Semi-Annual Research Division Forum (July 2008)
• . Berlin University of Technology Physics Seminar (January 2008)
• Diagnostics Needs for Energy Recovery Linacs. Scientific Assessment of FEL Technology Panel of the National Academy of Sciences (April 2008)
• X-Ray Applications and Accelerator Physics for the Cornell ERL. ELBE Workshop, Forschungszentrum Dresden-Rossendorf (October 2007)
• . Progress Toward an ERL Extension to CESR, Particle Accelerator Conference (June 2007)
• Considerations for the Cornell ERL Linac. Int. Workshop on Energy Recovery Linacs, Daresbury (May 2007)
• Coupler kicks in high Qext linacs. Int. Workshop on Energy Recovery Linacs, Daresbury (May 2007)
• Ions in ERLs. Int. Workshop on Energy Recovery Linacs, Daresbury (May 2007)
• CSR in x-ray ERLs. Int. Workshop on Energy Recovery Linacs, Daresbury (May 2007)
• Energy Recovery Linacs as x-ray sources. Int. Workshop on Energy Recovery Linacs, Daresbury (May 2007)
• The energy recovery linac (ERL) as a new x-ray source. Physics Colloquium, Argonne National Laboratory (March 2007)
• Toward an Energy Recovery Linac x-ray source at Cornell University. Accelerator Physics Seminar, Forschungs Zentrum Karlsruhe (May 2006)
• Summary of the Workingroup on ERLs. Workshop on Future Light Sources, Hamburg (May 2006)
• Toward an Energy Recovery Linac x-ray source at Cornell University. (with Ivan Bazarov), BNL Accelerator Physics Seminar (February 2006)
• Advanced Accelerator Physics at Cornell University (with David Rice, second part), DOE-AARD meeting, FNAL (February 2006)
  
• Toward an Energy Recovery Linac x-ray source at Cornell University, MIT CAST Seminar (February 2006)
  
• Overview of the working goup on Optics and Beams,
  G. H. Hoffstaetter, 1st ERL workshop, TJNAF, Newport News (March 2005)
• Optics considertions for ERL x-ray sources,
  G. H. Hoffstaetter, 1st ERL workshop, TJNAF, Newport News (March 2005)
• R&D accelerator issues for Linac-Ring Electron Ion Colliders,
  G. H. Hoffstaetter, 2nd EIC workshop, TJNAF, Newport News (March 2004)
• The Cornell ERL Project, NSCL Accelerator Physics Seminar, MSU (January 2004)
  

Accelerator physics for TESLA

The planning of a TeV Superconducting Linear Accelerator (TESLA) is the largest initiative at DESY for a future e+/e- linear collider. In an initial stage this accelerator will collider 250GeV electrons on 250GeV positrons. Such a large scale accelerator naturally consists of many subsystems which each have their own interesting accelerator physics issues. To test the main concepts and the main technical challenges of TESLA, the TESLA Test Facility (TTF) is being operated at DESY.

Publications

• Requirements for the Tilted TTF Bypass Line,
  G. Hoffstaetter, Report TESLA-2001-31 (2001)
• TESLA Technical Design Report, Part II: The Accelerator,
  J. Andruszkow et al., DESY-2001-011 and ECFA 2001-209 (2001)
• Bunch Compressor for the TESLA Linear Collider,
  W. Decking, G. Hoffstaetter, T. Limberg, Report TESLA-2000-40 (2000)

Accelerator physics for the HERA luminosity upgrade

When I moved to DESY in 1998, it had been planned to upgrade the HERA luminosity to 7.5*10^31/(cm^2 s), which was 5 times the original design luminosity. This was to be achieved by decreasing the proton beam size by moving quadrupoles closer to the interaction point and by increasing their strength. Similar measures decrease the electron beam size. However, to match the smaller proton beam size, the horizontal electron emittance additionally has to be decreased. Several aspects of electron and proton beam dynamics had to be considered in order to allow these changes in HERA.

Publications

• Coherent beam-beam tune shift of unsymmetrical beam-beam interactions with large beam-beam parameter,
  L. Jin, J. Shi, G. H. Hoffstaetter, Physical Review E 71, 036501 (2005)
  
• Study of beam-beam effects in HERA with selfconsistent beam simulations,
  J. Shi, L. Jin, G. H. Hoffstaetter, Proceedings of PAC'03, Portland (May 2003)
• Experiences with the HERA beams,
  G. H. Hoffstaetter, M. Vogt, F. Willeke, ICFA Newsletter (May 2003)
• Report from the HERA Taskforce on Luminosity Optimization: Theory and First Luminosity Scans,
  M. Dohlus, G. H. Hoffstaetter, M. Lomperski, R. Wanzenberg, Report DESY-HERA-2003-01 (January 2003)
• Beam-beam Limit with Hourglass Effect in HERA,
  G. H. Hoffstaetter and F. Willeke, Proceedings of EPAC'02, Paris, France (June 2002)
• Measurement of HERA's Central RF frequency,
  G. H. Hoffstaetter, B. Holzer, F. Willeke, and A. Meseck, Proceedings of EPAC'02, Paris, France (June 2002)
• Luminosity Scans at HERA,
  G. H. Hoffstaetter, Proceedings of EPAC'02, Paris, France (June 2002)
• Destabilizing Effect of Linear Coupling in the HERA Proton Ring,
  E. Metral, G. H. Hoffstaetter and F. Willeke, Proceedings of EPAC'02, Paris, France (June 2002)
• Orbit-Response Matrix Analysis at HERA,
  G. H. Hoffstaetter and J. Keil, Proceedings of EPAC'02, Paris, France (June 2002)
• Bunched Beam Echoes in the HERA Proton Ring,
  I. Agapov, G. H. Hoffstaetter and E. Vogel, Proceedings of EPAC'02, Paris, France (June 2002)
• Beam based alignment of combined function magnets in the upgraded HERA interaction region,
  F. Brinker, W. Decking, G. H. Hoffstaetter, J. Keil, T. Limberg, M. Minty, M. Seidel, R. Wanzenberg, F. Willeke, Proceedings of EPAC'02, Paris, France (June 2002)
• Beam Based Alignment of Interaction Region Magnets,
  G. H. Hoffstaetter and F. Willeke, Physical Review ST-AB, Volume 5, 102801 (October 2002)
• The Luminosity Upgrade of HERA,
  G. H. Hoffstaetter for the HERA Luminosity Upgrade Group, Beam Dynamics Newsletter N0. 24 (April 2001)
• Future HERA High Luminosity Performance,
  G. H. Hoffstaetter and F. Willeke, Proceedings HEACC (March 2001)
  Corresponding invited talk
• HERA Accelerator Studies 2000 ,
  Edited by G. H. Hoffstaetter, Report DESY-HERA-00-07 (November 2000)
• HERA Accelerator Studies,
  G. H. Hoffstaetter, Annual HERA Seminar (September 2000)
  Corresponding talk
• Future Possibilities for HERA,
  G. H. Hoffstaetter, EPAC 2000, Vienna (June 2000)
  Corresponding invited talk
• Electron Dynamics after the HERA Luminosity Upgrade,
  G. H. Hoffstaetter, EPAC 2000, Vienna (June 2000)
  Corresponding poster
• HERA accelerator studies 1999 ,
  Edited by G. H. Hoffstaetter, Report DESY-HERA-00-02 (May 2000)
• New Beam Optics for HERA-e: Theoretical Investigations and Experimental Tests ,
  G. H. Hoffstaetter, Proceedings of the HERA annual seminar, Report DESY-HERA-99-04 (1999)
• Recent and past experiences with beam-beam effects at HERA ,
  M. Bieler, E. Gianfelice-Wendt, G. H. Hoffstaetter, B. Holzer, S. Levonian, T. Limberg, M. Lomperski, M. Minty, Ch. Montag, R. Wanzenberg, M. Wendt, F. Willeke, K. Wittenburg, Proceedings of the Beam-beam-effects workshop, CERN (1999)
• Electron dynamics in the HERA luminosity upgrade lattice of the year 2000,
  G. H. Hoffstaetter and F. Willeke, Proceedings of PAC99 (1999)
• HERA machine studies December 1998 ,
  M. Bieler, E. Gianfelice-Wendt, G. H. Hoffstaetter, B. Holzer, C. Kleffner, T. Limberg, Ch. Montag, A. Meseck, M. Seidel, F. Solodovnik, M. Wendt, F. Willeke, K. Wittenburg, edited by G. H. Hoffstaetter, Report DESY-HERA-99-03 (March 1999)

Invited talks

• Beam-Beam Experience in HERA,
  G. H. Hoffstaetter, 2nd EIC workshop, TJNAF, Newport News (March 2004)
• Electron-ion collisions and other options for HERA,
  G. H. Hoffstaetter, IPPP workshop on future physics at HERA, Grey College, Durham 2001 (December 2001)
• Lepton Hadron Colliders,
  G. H. Hoffstaetter, Snowmass workshop on the future of high energy physics 2001,(July 2001)
• Beam-beam Experiments with HERA's Proton and Electron Beams,
  G. H. Hoffstaetter, Snowmass workshop on the future of high energy physics 2001,(July 2001)
• Future HERA High Luminosity Performance,
  G. H. Hoffstaetter and F. Willeke, HEACC 2001, Tsukuba (March 2001)
• Future Possibilities for HERA,
  G. H. Hoffstaetter, EPAC 2000, Vienna (June 2000)

Dynamics of polarized beams

The changes required for accelerating and storing polarized beams in the proton accelerators at DESY were investigated. For these studies the particle and spin dynamics program SPRINT was developed. The basis of this program is the "stroboscopic average", which is used to compute invariant subsets of the coupled spin and orbit dynamics. These invariants limit the polarization in a proton beam at HERA.

Publications

• Adiabatic invariance of spin-orbit motion in accelerators,
  G.H. Hoffstaetter, H.S. Dumas, J.A. Ellison, Physical Review ST-AB 8, 014001 (2006)
• Observation of Snake Resonances in RHIC,
  M. Bai, H. Huang, W. Mac Kay, V. Ptitsin, T. Roser, S. Tepikian, G.H. Hoffstaetter, S.Y. Lee, F. Lin, Proceedings PAC05, Knoxville/TN (2005)
• Optimal Axes of Siberian Snakes for Polarized Proton Acceleration,
  G. H. Hoffstaetter, Physical Review ST-AB, 7, 121001 (2004)
• Strength of Higher-Order Spin-Orbit Resonances,
  G. H. Hoffstaetter, M. Vogt, Physical Review E 70, 056501 (2004)
• Matching of Siberian Snakes,
  G. H. Hoffstaetter, AIP Proceedings, Ann Arbor (November 2002)
• Accelerator rings with polarized beams and spin manipulation,
  G. H. Hoffstaetter, Lecture for the COSY Summer School (August 2002)
• Adiabatic Invariants for Spin-Orbit Motion,
  G. H. Hoffstaetter, S. Dumas, J. A. Ellison, Proceedings of EPAC'02, Paris/France (June 2002)
• Polarised Protons in HERA,
  D. Barber, G. H. Hoffstaetter, M. Vogt, Proceedings of EPAC'02, Paris, France (June 2002)
• Beam Dynamics Activities at the University of New Mexico,
  J. Ellison et al., ICFA Beam Dynamics Newsletter (April 2001)
• Using the amplitude dependent spin tune to study high order spin-orbit resonances in storage rings,
  D. P. Barber, G. H. Hoffstaetter, and M. Vogt, Proceedings of 14th International Spin Physics Symposium SPIN00, Osaka, Japan (2000)
• Proton and electron polarisation in storage rings: some basic concepts,
  D. P. Barber, G. H. Hoffstaetter, and M. Vogt, Proceedings of 2nd Wokshop on Physics with a Polarized-Electron Light-ion Collider (EPIC), MIT (MA/USA) (2000)
• Higher-order effects in polarized proton dynamics,
  G. H. Hoffstaetter, M. Vogt, and D. P. Barber, Physical Review ST-AB, Volume 2, Number 114001 (November 1999)
• Polarized protons in HERA,
  G. H. Hoffstaetter, Nuclear Physics A666/&667 203c--213c (2000)
• Polarized protons at HERA: the accelerator issues,
  G. H. Hoffstaetter, Proceedings of the Workshop on Polarized Protons at High Energies, DESY-PROC-99-03 (1999)
• Numerical and theoretical spin stability studies for HERA-p,
  D. P. Barber, G. H. Hoffstaetter and M. Vogt, Proceedings of the Workshop on Polarized Protons at High Energies, Report DESY-PROC-99-03 (1999)
• Nonlinear spin transfer maps,
  C. Weissbaecker and G. H. Hoffstaetter, Proceedings of the Workshop on Polarized Protons at High Energies, Report DESY-PROC-99-03 (1999)
• Spin motion at high energy in HERA-p,
  D. P. Barber, G. H. Hoffstaetter, and M. Vogt, In University of Michigan Report UM-HE-99-05 (1999)
• Snake matching,
  G. H. Hoffstaetter, In University of Michigan Report UM-HE-99-05 (1999)
• Acceleration of Polarized Protons to 920 GeV at HERA,
  The SPIN Collaboration and the DESY Polarization Team, University of Michigan Report UM-HE-99-05 (1999)
• The amplitude dependent spin tune and the invariant spin field in high energy proton accelerators,
  D. P. Barber, G. H. Hoffstaetter, and M. Vogt, Proceedings SPIN98, Protvino (1998)
• The amplitude dependent spin tune and the invariant spin field in high energy proton accelerators,
  D. P. Barber, G. H. Hoffstaetter, and M. Vogt, Proceedings of EPAC98 (1998)
  Corresponding poster
• Introduction to the invariant spin field and update on simulations with polarized protons at HERA-p,
  M. Vogt, D. P. Barber, and G. H. Hoffstaetter, Proceedings of the HERA annual seminar, Report DESY-HERA-98-04 (1998)
• The permissible equilibrium polarization distribution in a stored proton beam,
  D. P. Barber, K. Heinemann, G. H. Hoffstaetter, and M. Vogt, ICFA Proceedings Quantum Aspects of Beam Physics (1998)
• Differential Algebra for the Computation of Polarization Dynamics,
  G. H. Hoffstaetter, unpublished (1998)
• Polarized protons in HERA - the status,
  D. P. Barber, M. Vogt, and G. H. Hoffstaetter, in Report DESY-97-200 (1997) and DESY-Proceedings-1998-01 (1998)
• Higher-order effects in polarized proton dynamics,
  G. H. Hoffstaetter, M. Vogt, and D. P. Barber, DESY-97-161 (1997)
• The polarization at high energy in HERA,
  D. P. Barber, K. Heinemann, G. H. Hoffstaetter, and M. Vogt, Report DESY-HERA-96-07 and in University of Michigan Report UM-HE-96-20 (1996)
• Acceleration of Polarized Protons to 820 GeV at HERA,
  The SPIN Collaboration and the DESY Polarization Team, University of Michigan Report UM-HE-96-20 (1996), (without figures)
• Polarized protons in HERA,
  G. H. Hoffstaetter, Proceedings of SPIN96, Amsterdam (1996)
• Calculations of the equilibrium spin distribution for protons at high energy in HERA,
  D. P. Barber, K. Heinemann, G. H. Hoffstaetter, and M. Vogt, Proceedings of SPIN96, Amsterdam (1996)
• Stroboscopic averaging for computing the equilibrium spin direction in storage rings,
  K. Heinemann and G. H. Hoffstaetter, 1996 unpublished
• The phase space dependent spin polarization direction in the HERA proton ring at high energy,
  D. P. Barber, K. Heinemann, G. H. Hoffstaetter, and M. Vogt, Report DESY-M-96-14 and Proceedings EPAC96 (1996)
• Polarized protons in HERA,
  D. P. Barber, K. Heinemann, G. H. Hoffstaetter, and M. Vogt, in Future Physics at HERA, Volume 2, DESY (1996)
• Tracking algorithm for the stable spin polarization field in storage rings using stroboscopic averaging,
  K. Heinemann and G. H. Hoffstaetter, Physical Review E 54, 4 (November 1996)
  
• Polarized protons in HERA,
  G. H. Hoffstaetter, in Report DESY-HERA-96-05 (1996)

Invited talks

• Matching of Siberian Snakes,
  G. H. Hoffstaetter, Workshop on Polarized Protons in the AGS, Ann Arbor (November 2002)
• Polarized Particle Beams,
  G. H. Hoffstaetter, COSY Summer School, KFA Juelich (August 2002)
• Polarized protons in HERA,
  G. H. Hoffstaetter, NUCLEON 99, INFN Frascati (June 1999)
• Polarized protons at HERA: the accelerator issues,
  G. H. Hoffstaetter, Workshop on Polarized Protons at High Energies - Accelerator Challenges and Physics Opportunities, DESY Hamburg (May 1999)
• Polarized Protons at HERA ,
  G. H. Hoffstaetter, APS Meeting, Columbus Ohio (April 1998)
• Polarized protons in HERA,
  G. H. Hoffstaetter, 12th International Symposium on High-Energy Spin Physics (SPIN96), Amsterdam (September 1996)
• Spin Dynamics,
  G. H. Hoffstaetter, Mathematical Aspects of Accelerator Physics, Bad Honnef (9-13 December 1996)

Long term stability in storage rings

Nonlinear normal form theory and interval arithmetic were used to make rigorous and therefore extremely reliable statements about the time for which particles can be stored in circular accelerators. Applications to other weakly nonlinear dynamical systems are possible.

Publications

• Methods of bounding long term stability in storage rings by estimating pseudo invariants of nonlinear motion,
  G. H. Hoffstaetter, M. Berz, Particle Accelerators, unpublished
• Rigorous lower bounds on the survival time in particle accelerators,
  G. H. Hoffstaetter, M. Berz, Particle Accelerators 54, 193-202 (1996)
• Rigorous bounds on survival times in circular accelerators and efficient computation of fringe-field transfer maps,
  G. H. Hoffstaetter, Dissertation, Report DESY-94-242 (1994), (some figures missing)
• Computation and application of Taylor polynomials with remainder bounds,
  M. Berz and G. H. Hoffstaetter, Reliable Computing 4: 83-97 (1998)
• Exact estimates of the long term stability of weakly nonlinear systems applied to the design of large storage rings,
  M. Berz and G. H. Hoffstaetter, Interval Computations, Number 2, 68-89 (1994)
• Rigorous stability estimates,
  G. H. Hoffstaetter, M. Berz, NSCL Annual Report, 186-189 (1993)
• Refinement of the normal form method for long term stability estimates,
  G. H. Hoffstaetter, M. Berz, NSCL Annual Report, 182-185 (1993)
• Survival times of particles in storage rings,
  G. H. Hoffstaetter and M. Berz, NSCL Annual Report, 221-225 (1992)

Particle dynamics in electromagnetic fringe fields

Using differential algebra, a method was developed which allows a very efficient and accurate computation of the particle dynamics in fringe fields. Since then this method was used in the design and simulation of several spectrometers and accelerators.

Publications

• Symplectic scaling of transfer maps including fringe fields,
  G. H. Hoffstaetter and M. Berz, Physical Review E, 54, 4 (1996)
• Accurate and fast computation of high order fringe-field maps via symplectic scaling,
  G. H. Hoffstaetter and M. Berz, Nuclear Instruments and Methods in Physics Research A 363, 124-127 (1995)
• An efficient symplectic approximation for fringe-field maps,
  G. H. Hoffstaetter and M. Berz, AIP Conference Proceedings 297, Computational Accelerator Physics, Los Alamos, NM, 467-476 (1993)
• Symplectic scaling, a DA based tool, proceedings of the accelerator physics conference,
  G. H. Hoffstaetter and M. Berz, Proceedings of PAC93, Washington DC (1993)
• Applications of symplectic scaling,
  G. H. Hoffstaetter and M. Berz, NSCL Annual Report, 206-209 (1992)
• Fringe-field approximations,
  G. H. Hoffstaetter, M. Berz, NSCL Annual Report, 236-241 (1991)

Invited talk

• Computation of high order fringe-field effects in spectrographs,
  G. H. Hoffstaetter, APS Meeting, Crystal City/MD (April 1994)

Particle optics in electron microscopes

Tolerances and optical properties of electron optical devices with nonlinear fields were investigated. Of special interest were tolerances of the sextupole fields which were used by Dr. M. Haider in 1997 to obtain a world record of resolution.

Publications

• Comments on aberration correction in symmetric imaging energy filters,
  G. H. Hoffstaetter, Nuclear Instruments and Methods in Physics Research A 427, 275-281 (1999)
• Gauge invariance in the eikonal method,
  G. H. Hoffstaetter and H. Rose, Nuclear Instruments and Methods in Physics Research A 328, 398-401 (1993)
• Geometrische Elektronenoptik angewandt auf ein durch Hexapole korrigiertes Mikroskop mit sub Angström Auflösung,
  G. H. Hoffstaetter, Diplomarbeit, Technische Hochschule Darmstadt (1991)

Other subjects

Here are the titles of publications which can not be collected under a common header.

Publications

• Editorial: In memory of Robert H. Siemann, D. Brodbar, G. H. Hoffstaetter, B. Johnson, D. T. Kulp, G.D. Sprouse, C. Wesselborg, F. Zimmermann, Physical Review ST-AB, Volume 1, 100002 (2008)
• Synchro-Betatron Stop-Bands due to a Single Crab Cavity, G. H. Hoffstaetter, A. Chao, Physical Review ST-AB, Volume 7, 071002 (2004)
• Investigation of the Flat-Beam Model of the Beam-Beam Interaction, B. S. Schmekel, G. H. Hoffstaetter, J. T. Rogers, Physical Review ST-AB, Volume 6, 104403 (2003)
• Investigation of the flat-beam model of the beam-beam interaction,
  B. Schmekel, G. H. Hoffstaetter, J. Rogers, Proceedings of PAC'03, Portland (May 2003)
• Executive summary of the M5 working group on Lepton-Hadron Colliders,
  I. Ben-Zvi and G. H. Hoffstaetter (eds.), proceedings of the Snowmass 2001 workshop on the future of particle physics (July 2001)
• Report of the M5 working group on Lepton-Hadron Colliders,
  I. Ben-Zvi and G. H. Hoffstaetter (eds.), proceedings of the Snowmass 2001 workshop on the future of particle physics (July 2001)
• Successive approximations for charged particle motion,
  G. H. Hoffstaetter, Ultramicroscopy, Volume 81, Issue 3-4, (April 2000)
• Computation and application of Taylor polynomials with remainder bounds,
  M. Berz and G. H. Hoffstaetter, Reliable Computing 4: 83-97 (1998)
• COSY INFINITY and its applications in nonlinear dynamics,
  M. Berz, K. Makino, K. Shamseddine, G. H. Hoffstaetter, and W. Wan, in Computational Differentiation, Techniques, Applications, and Tools, 363-367, SIAM (1996)
• Nonlinear dependence of synchrotron radiation on beam parameters,
  G. H. Hoffstaetter, Proceedings PAC95, Dallas/TX (1995)
• New features in COSY INFINITY,
  M. Berz, M. Zhao, W. Wan, and G. H. Hoffstaetter, NSCL Annual Report, 230-231 (1991)

Invited talks

• State of the Art in Particle Tracking,
  G. H. Hoffstaetter, ICAP2000, Darmstadt, Germany (September 2000)
• Posters: 2

Supported Students

Doctoral students

• Chris E. Mayes (PhD 2009), Thesis: Energy Recovery Linear Accelerator Lattice Design &Coherent Synchrotron Radiation, chairperson of PhD committee and supervisor of dissertation: Georg H. Hoffstaetter
• Richard Helms (PhD 2007), collaborated on nonlinear evaluation of Beam Position Monitor data, Thesis: Studies for CESR-TA: A low-emittance test accelerator at the Cornell Electron Storage Ring, chairperson of PhD committee: David Rubin
• Bjoern Schmekel (2005), collaborated on the beam-beam effect and Coherent Synchrotron Radiation, Thesis: Collisionless Beam-Radiation Processes in the Laborator and Astrophysics, chairperson of PhD committee: Ira Wasserman
• Ilya Agapov (2005), collaborated on longitudinal bunched beam echos, Thesis: Mechanisms of loss of high energy protons from the bunched beams in storage rings, chairperson of PhD committee: Ursula van Rienen
• Mathias Vogt (2000), joint supervision with Dr. Desmond Barber, Thesis: Bounds on the Maximum Attainable Equilibrium Spin Polarization of Protons at High Energy in HERA, supervising full professor: Gustav Kramer

Master Degrees

• Yang Hao Lau (2008), Wake field compensation, recipient of the David Delano Clark award for the best Master in Engineering project in 2008, handed out by the department of Applied Engineering and Physics at Cornell University
• Yi Xie (2007), Short-range wakefield calculations for the ion clearing electrodes in the Cornell Energy Recovery Linac
• Changsheng Song (2006), Beam-breakup instability and sensitivity to field errors in ERLs
• Joseph Choi (2005), Phase-space propagatin in ERLs

Collaborating Graduate Students

• Sam Posen (2009 - )
• Michael Ehrlichmann (2008 - )
• Mike Saelim (2008)
• Christian Spethmann (2007)
• Greg Stiesberg (2006)

Undergraduate Research Experience

• Joel Thompson (2008-2009), Bunch compression for a short-pulse mode in Cornell's ERL
• Christopher Macgahan(2008), Ion distributions around electron beams
• Udom Sae-Ueng (2008), Simulations of Coherent Synchrotron Radiation (CSR)
• Michael Martin (2007), An graduate-lab experiment in accelerator physics
• Brandon Buckly (2007), Coupler kicks and their compensation
• Vaibhav Kukreja (2006), Electron Field-Emission in the ERL-Electron Source and the Projection Model
• Shaan Qamar (2005), Coupler kick simulations
• Nabil Igbal (2004), A test stand for beam-position measurements
• Tomohiko Tanabe (2004), Syncrotron radiation shielding in SRF linacs
• Andrew Schwarzkopf (2004), Beam-position monitor errors
• Igor Senderovich (2004), Electrode design adjustments to a high voltage electron gun
• Jonathan Bergknoff (2004), Communication between C++ and FORTRAN for a beam-dynamics library
• Gideon Alon (2003), Beam-Breakup Instabilities

Students for REU (Research Experience for Undergraduates)

• Eric Edwards (2008), Time-of-flight Identification of Ions in CESR and ERL
• Robin Bjorkquist (2008), Evaluation of a New Cavity Focusing Theory
• Adra (Tory) Carr (2006), Coherent Synchrotron Radiation
• Vaibhav Kukreja (2005), Field-Emission Properties in the ERL-Electron Source
• Chanisha Martin (2004), Ground-motion measurements for potential ERL sites
• Christopher Chan (2004), Beam position monitor test stand
• Beau Meredith (2003), Pick-up calibration in CESR beam position monitors
• Charalambos (Bobby) Koupparis (2003), Determination of ERL optics with undulators

Diploma theses

• Nichtlineare Effekte der Spindynamik in Protonenbeschleunigern,
  Christoph Weisbaecker, supervising full professor: Harald Rose (1998), DESY-THESIS-1999-019
  Talk on 19th of May 1999
• Manipulation des Öffnungsfehlers bei der elektronenoptischen Abbildung schwacher Phasenobjekte,
  Achim Hohl, supervising full professor: Harald Rose (1998)

Highschool interns (through the Ithaca learning Web)

• Alexander Naydich (2006), Wiki oranization for WBS structures
• Shaan Qamar (2004), Emittance growth from coupler ckicks
• Anton Kriksunov (2003), Optimizers for particle-optics simulations

General lectures

• Advanced-Accelerator Physics and Simulation, P488/688, Cornell University, spring 2007
  
• CESR-CLEO mini course, December 2006
• Modern Optics, P330, Cornell University, fall 2006
• Advanced-Accelerator Physics and Simulation, Boston University, summer 2006
• Modern Optics, P330, Cornell University, fall 2005
• Modern Physics, P316, Cornell University, spring 2005
• Advanced Topics in Accelerator Physics, P488/688, Cornell University, fall 2004
• Modern Physics, P316, Cornell University, spring 2004
• Introduction to Accelerator Physics and Technology, P456/656, Cornell University, fall 2003
  
• Modern Physics, P316, Cornell University, spring 2003
• Accelerator rings with polarized beams and spin manipulation: talk and associated paper,
  Lecture in the COSY Summer School 2002
• Introduction to Accelerators II, University of Hamburg (with Prof. P. Schmueser), fall 1999 and spring 2002
  
• Introduction to Accelerators I University of Hamburg (with Prof. P. Schmueser), spring 1999 and fall 2001
  
• Chaos oder Stabilität im Sonnensystem
  Talk in the DESY seminar for general education
• The physics of accelerators
  3.5 hours lecture for the DESY summer sudent program 1999, 2000 and '01
• A review of electrodynamics
  2 hours lecture for the Joint Universities Accelerator School (JUAS) 2000, '01 and '02
• A review of special relativity
  2 hours lecture for the Joint Universities Accelerator School (JUAS) 2000, '01 and '02
• Introduction into theoretical physics
  Link at the Mathematica Courseware Catalog
• Theoretical physics 0/1/2
  Assignments and exams for the theoretical physics lectures 0, 1, and 2, 1997-1998, Darmstadt University of Technology