Paper |
Title |
Page |
MOPKF071 |
Study of Row Phase Dependent Skew Quadrupole Fields in Apple-II type EPUs at the ALS
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479 |
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- C. Steier, S. Marks, S. Prestemon, D. Robin, R.D. Schlueter, A. Wolski
LBNL, Berkeley, California
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Since about 5 years, Apple-II type Elliptically Polarizing Undulators (EPU) have been used very successfully at the ALS to generate high brightness photon beams with arbitrary polarization. However, both EPUs installed so far cause significant changes of the vertical beamsize, especially when the row phase is changed to change the polarization of the photons emitted. The effect has been measured in detail and turned out to be caused by a row phase dependent skew quadrupole term in the EPUs. Magnetic measurements revealed the same effect for the third EPU to be installed later this year. All measurements to identify and quantify the effect with beam will be presented, as well as results of magnetic bench measurements and numeric field simulations.
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MOPKF072 |
Towards Attosecond X-ray Pulses from the FEL
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482 |
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- A. Zholents, J.M. Byrd, W. Fawley, Z. Hao, M.C. Martin, D. Robin, F. Sannibale, R.W. Schoenlein, M. Venturini, M.S. Zolotorev
LBNL, Berkeley, California
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The ability to study ultrafast phenomena has been recently advanced by the demonstrated production and measurement of a single, 650-attosecond, soft x-ray pulses precisely synchronized to the pump laser pulse consisted of just few optical cycles. The next frontier is a production of attosecond x-ray pulses at even shorter wavelengths. Here we propose the method of ?seeded attosecond x-ray radiation? where an isolated, attosecond duration, short-wavelength x-ray pulse is radiated by electrons selected by their previous interaction with a few-cycle, intense laser pulse. In principle this method allows excellent synchronization between the attosecond x-ray probe pulse and a pump source that can be the same few-cycle laser pulse or another signal derived from it.
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WEPLT147 |
Lattice Studies for CIRCE (Coherent InfraRed CEnter) at the ALS
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2179 |
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- H. Nishimura, D. Robin, F. Sannibale, W. Wan
LBNL, Berkeley, California
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CIRCE (Coherent InfraRed Center) at the Advanced Light Source is a proposal for a new electron storage ring optimized for the generation of coherent synchrotron radiation (CSR) in the terahertz frequency range. One of the main requirement for this special mode of operation is the capability of the ring of operating at very small momentum compaction values. In this regime, the longitudinal dynamics becomes strongly nonlinear and an accurate control of the higher order energy dependent terms of the momentum compaction is necessary. The lattice for CIRCE allows controlling these terms up to the third order. The paper describes the lattice and presents the calculated performances in terms of momentum acceptance, dynamic aperture, lifetime and momentum compaction tune capabilities.
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THPKF073 |
CIRCE, the Coherent InfraRed CEnter at the ALS
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2433 |
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- J.M. Byrd, S. De Santis, J.-Y. Jung, M.C. Martin, W.R. McKinney, D.V. Munson, H. Nishimura, D. Robin, F. Sannibale, R.D. Schlueter, M. Venturini, W. Wan, M.S. Zolotorev
LBNL, Berkeley, California
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CIRCE (Coherent InfraRed Center) is a new electron storage ring to be built at the Advanced Light Source (ALS) of the Lawrence Berkeley National Laboratory (LBNL). The ring design is optimized for the generation of coherent synchrotron radiation (CSR) in the terahertz frequency range. CIRCE operation includes three possible modes: ultra stable CSR, femtosecond laser slicing CSR and broadband SASE. CSR will allow CIRCE to produce an extremely high flux in the terahertz frequency region. The many orders of magnitude increase in the intensity is the basis of our project and enables new kinds of science. The characteristics of CIRCE and of the different modes of operation are described in this paper.
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THPKF076 |
Plan to Upgrade the Advanced Light Source to Top-off Injection Operation
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2439 |
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- D. Robin, B. J. Bailey, K.M. Baptiste, W. Barry, E. Byrne, J.-Y. Jung, S. Kwiatkowski, R.S. Mueller, H. Nishimura, S. Prestemon, S.L. Rossi, F. Sannibale, D. Schlueter, D. Shuman, C. Steier, G.D. Stover, T. Warwick
LBNL, Berkeley, California
- R.J. Donahue
LBNL/ALS, Berkeley, California
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The brightness and thermal stability of the Advanced Light Source (ALS) is lifetime limited. Brightness improvements such as narrower gap insertion devices, smaller emittance coupling, and higher currents all result in short lifetimes. In addition current changes over a fill impact the thermal stability of both the storage ring and beamlines. In order to mitigate these limitations there is a plan to upgrade the injector of the ALS to full energy injection and to operate in a quasi-continuous filling (Top-Off) injection operation. With Top-Off, the ALS will increase its time-averaged current by two, reduce the vertical emmittance, and operate with smaller gap insertion devices. In this paper we describe our upgrade plan.
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THPKF078 |
Coherent Infrared Radiation from the ALS Generated via Femtosecond Laser Modulation of the Electron Beam
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2445 |
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- A. Zholents, J.M. Byrd, Z. Hao, M.C. Martin, D. Robin, F. Sannibale, R.W. Schoenlein, M. Venturini, M.S. Zolotorev
LBNL, Berkeley, California
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Interaction of an electron beam with a femtosecond laser pulse co-propagating through a wiggler at the ALS produces significant modulation of the electron energies within a short ~100 fs slice of the electron bunch. Subsequent propagation of the energy-modulated bunch around the storage ring results in an appearance of a local temporal modulation of the electron density (micro-bunching) due to the dispersion of electron trajectories. The temporal width of this perturbation evolves as the electron bunch propagates around the ring. The shortest modulation, ~50 microns, appears in the ALS sector immediately following the wiggler magnet, and stretches to ~ 500 microns following propagation over 2/3 of a storage ring orbit. The modulated electron bunch emits single-cycle pulses of temporally and spatially coherent infrared light which are automatically synchronized to the laser pulses. The intensity and spectra of the infrared light were measured in two locations in the ring indicated above and were found to be in good agreement with analytical calculations. Ultra-short pulses of coherent infrared radiation are presently used for a fine tuning the laser ? electron beam interaction for generating femtosecond x-ray pulses.
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THOACH01 |
SPEAR3 Commissioning
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216 |
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- J.A. Safranek, S. Allison, P. Bellomo, W.J. Corbett, M. Cornacchia, E. Guerra, R.O. Hettel, D. Keeley, N. Kurita, D.J. Martin, P.A. McIntosh, H. Morales, G.J. Portmann, F.S. Rafael, H. Rarback, J.J. Sebek, T. Straumann, A. Terebilo, J. Wachter, C. Wermelskirchen, M. Widmeyer, R. Yotam
SLAC/SSRL, Menlo Park, California
- M.J. Boland, Y.E. Tan
ASP, Melbourne
- J.M. Byrd, D. Robin, T. Scarvie, C. Steier
LBNL/ALS, Berkeley, California
- M. Böge
PSI, Villigen
- H.-P. Chang, C.-C. Kuo, H.-J. Tsai
NSRRC, Hsinchu
- W. Decking
DESY, Hamburg
- M.G. Fedurin, P. Jines
LSU/CAMD, Baton Rouge, Louisiana
- K. Harkay, V. Sajaev
ANL/APS, Argonne, Illinois
- S. Krinsky, B. Podobedov
BNL/NSLS, Upton, Long Island, New York
- L.S. Nadolski
SOLEIL, Gif-sur-Yvette
- A. Ropert
ESRF, Grenoble
- M. Yoon
POSTECH, Pohang, Kyungbuk
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Starting in April, 2003, the SPEAR2 storage ring was removed and replaced with a new 500 mA, 3 GeV light source, SPEAR3. The SPEAR2 storage ring had been in use for high energy physics, then synchrotron radiation since 1972. Commissioning of SPEAR3 started on December 8, 2003 and synchrotron radiation will be delivered to the first users on March 8, 2004. SPEAR3 commissioning will be reviewed, including discussion of diagnostics, orbit control, optics correction and high current studies.
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Video of talk
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Transparencies
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