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1. The fluctuation-dissipation measurement instrument at the Linac Coherent Light Source

Author

T. A. Assefa, M. H. Seaberg, A. H. Reid, L. Shen, V. Esposito, G. L. Dakovski, W. Schlotter, B. Holladay, R. Streubel, S. A. Montoya, P. Hart, K. Nakahara, S. Moeller, S. D. Kevan, P. Fischer, E. E. Fullerton, W. Colocho, A. Lutman, F.-J. Decker, S. K. Sinha, S. Roy, E. Blackburn, and J. J. Turner

Subjects
Instrumentation
Abstract

The development of new modes at x-ray free electron lasers has inspired novel methods for studying fluctuations at different energies and timescales. For closely spaced x-ray pulses that can be varied on ultrafast time scales, we have constructed a pair of advanced instruments to conduct studies targeting quantum materials. We first describe a prototype instrument built to test the proof-of-principle of resonant magnetic scattering using ultrafast pulse pairs. This is followed by a description of a new endstation, the so-called fluctuation–dissipation measurement instrument, which was used to carry out studies with a fast area detector. In addition, we describe various types of diagnostics for single-shot contrast measurements, which can be used to normalize data on a pulse-by-pulse basis and calibrate pulse amplitude ratios, both of which are important for the study of fluctuations in materials. Furthermore, we present some new results using the instrument that demonstrates access to higher momentum resolution.

Published
2022

2. Population inversion X-ray Laser Oscillator at LCLS

Author

A. Halavanau, F. Fuller, T. Kroll, A. Lutman, A. Aquila, F.-J. Decker, C. Pellegrini, N. Welke, R. Ash, U. Bergmann, A. Benediktovitch, N. Rohringer, S. Krusic, M. Doyle, P. Manwani, N. Majernik, and J. Rosenzweig

Abstract

We present design and characteristics of a population inversion X-ray laser oscillator (XLO) at LCLS. We report on first experiments and future plans towards XLO demonstration. We also discuss necessary upgrades to LCLS for optimized XLO performance.

Published
2022
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3. Ultra-fast transverse beam orbit control in LCLS copper linac. Part I

Author

A. Halavanau, A. Romero, A. Krasnykh, A. Lutman, T. Beukers, J. Hugyik, A. Le, K. Luchini, E. Jongewaard, A. Sy, A. Ibrahimov, A. Benwell, A. Marinelli, and F.-J. Decker

Subjects
Instrumentation, Mathematical Physics
Abstract

Current and future experiments at LCLS require x-ray pulse trains of variable time separation on the nanosecond scale. For instance, the cavity-based XFEL (CBXFEL) will use up to 4 pulses separated by 218.5 ns, the X-ray Laser Oscillator (XLO) will use 15 to 25 ns spaced pulses, and the Matter under Extreme Conditions (MEC) experiments use pulse trains separated by 5 nanoseconds or less. In this paper, we demonstrate an ultra-fast e-beam trajectory control method based on transverse electro-magnetic (TEM) striplines and state-of-the-art power sources, to enhance LCLS operations in these regimes.

Published
2022
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4. Generation of High-Power High-Intensity Short X-Ray Free-Electron-Laser Pulses

Author

Alberto Lutman, Marc W. Guetg, T. Maxwell, F.-J. Decker, Uwe Bergmann, Yuantao Ding, and Zhirong Huang

Subjects
Photon, Materials science, business.industry, Free-electron laser, General Physics and Astronomy, Pulse duration, 02 engineering and technology, Pulsed power, 021001 nanoscience & nanotechnology, Laser, 01 natural sciences, Electromagnetic radiation, law.invention, Optics, law, 0103 physical sciences, Physics::Accelerator Physics, 010306 general physics, 0210 nano-technology, business, Beam (structure), Coherence (physics)
Abstract

X-ray free-electron lasers combine a high pulse power, short pulse length, narrow bandwidth, and high degree of transverse coherence. Any increase in the photon pulse power, while shortening the pulse length, will further push the frontier on several key x-ray free-electron laser applications including single-molecule imaging and novel nonlinear x-ray methods. This Letter shows experimental results at the Linac Coherent Light Source raising its maximum power to more than 300% of the current limit while reducing the photon pulse length to 10 fs. This was achieved by minimizing residual transverse-longitudinal centroid beam offsets and beam yaw and by correcting the dispersion when operating over 6 kA peak current with a longitudinally shaped beam.

Published
2018
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5. Coherent electron beam density modulator for driving X-ray free electron lasers

Author

Bob Hettel, F.-J. Decker, Alexander Novokhatski, Michael Sullivan, and Yu. Nosochkov

Subjects
Free electron model, Physics, Nuclear and High Energy Physics, Klystron, business.industry, Astrophysics::High Energy Astrophysical Phenomena, Free-electron laser, Undulator, Laser, Linear particle accelerator, law.invention, Optics, law, Cathode ray, Physics::Accelerator Physics, Laser beam quality, business, Instrumentation
Abstract

We propose a new compact scheme for a Free Electron Laser with more coherent properties for the X-ray beam. Higher FEL performance would be achieved using a train of electron bunches initially accelerated in a linear accelerator. Similar to the RF klystron concept, we propose developing an X-ray FEL which consists of two parts: an X-ray self-seeding electron beam density modulator and an output set of undulators. A density modulator consists of a low-Q X-ray cavity and an undulator, which is placed between the cavity mirrors. We use this undulator as a very high gain amplifier, which compensates the amplitude loss due to monochromatic X-ray reflections from the mirrors. Following the X-ray cavity, the density modulated electron beam is separated from the X-ray beam and then enters the output set of undulators. The frequency spectrum of the final X-ray beam is determined mainly by the bandwidth of the reflected elements in the X-ray cavity.

Published
2015
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6. Nanosecond X-Ray Photon Correlation Spectroscopy on Magnetic Skyrmions

Author

Sashwati Roy, S. A. Montoya, B. Holladay, William F. Schlotter, Marcin Sikorski, Joshua J. Turner, Eric E. Fullerton, James Lee, Stefan Moeller, F.-J. Decker, Matthew Seaberg, Giacomo Coslovich, Shantanu Sinha, Alexander H. Reid, Georgi L. Dakovski, James Turner, Stephen D. Kevan, Robert Streubel, Peter Fischer, and Jake Koralek

Subjects
Physics, Condensed matter physics, Scattering, Skyrmion, General Physics and Astronomy, 02 engineering and technology, X-ray Photon Correlation Spectroscopy, Nanosecond, 021001 nanoscience & nanotechnology, 01 natural sciences, Linear particle accelerator, Dynamic light scattering, Lattice (order), 0103 physical sciences, Thin film, 010306 general physics, 0210 nano-technology
Abstract

We report an x-ray photon correlation spectroscopy method that exploits the recent development of the two-pulse mode at the Linac Coherent Light Source. By using coherent resonant x-ray magnetic scattering, we studied spontaneous fluctuations on nanosecond time scales in thin films of multilayered Fe/Gd that exhibit ordered stripe and Skyrmion lattice phases. The correlation time of the fluctuations was found to differ between the Skyrmion phase and near the stripe-Skyrmion boundary. This technique will enable a significant new area of research on the study of equilibrium fluctuations in condensed matter.

Published
2017
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7. Negative Pressures and Spallation in Water Drops Subjected to Nanosecond Shock Waves

Author

Claudiu A. Stan, James Turner, Philip R. Willmott, Gabriel Blaj, Mengning Liang, Serge Guillet, Andrew Aquila, Howard A. Stone, Jason E. Koglin, Sharon Vetter, F.-J. Decker, Henrik Loos, Robin Curtis, Karl Gumerlock, Raymond G. Sierra, Sébastien Boutet, and Joseph Robinson

Subjects
Shock wave, Chemistry, Drop (liquid), Nucleation, 02 engineering and technology, Mechanics, Nanosecond, 021001 nanoscience & nanotechnology, Laser, 01 natural sciences, law.invention, law, Homogeneous, Cavitation, 0103 physical sciences, General Materials Science, Spallation, Physical and Theoretical Chemistry, 010306 general physics, 0210 nano-technology, Nuclear chemistry
Abstract

Most experimental studies of cavitation in liquid water at negative pressures reported cavitation at tensions significantly smaller than those expected for homogeneous nucleation, suggesting that achievable tensions are limited by heterogeneous cavitation. We generated tension pulses with nanosecond rise times in water by reflecting cylindrical shock waves, produced by X-ray laser pulses, at the internal surface of drops of water. Depending on the X-ray pulse energy, a range of cavitation phenomena occurred, including the rupture and detachment, or spallation, of thin liquid layers at the surface of the drop. When spallation occurred, we evaluated that negative pressures below −100 MPa were reached in the drops. We model the negative pressures from shock reflection experiments using a nucleation-and-growth model that explains how rapid decompression could outrun heterogeneous cavitation in water, and enable the study of stretched water close to homogeneous cavitation pressures.

Published
2016

8. Demonstration of self-seeding in a hard-X-ray free-electron laser

Author

H. Loos, F.-J. Decker, Jacek Krzywinski, William Berg, Heinz-Dieter Nuhn, J. Welch, J. Amann, Simone Spampinati, Jerome B. Hastings, Jihuai Wu, Alexander Zholents, Y. Ding, J. Rzepiela, P. Emma, Zhirong Huang, Stanislav Stoupin, Daniel Ratner, Vladimir Blank, J. Frisch, D.R. Walz, Yiping Feng, Diling Zhu, David Fritz, Emil Trakhtenberg, Ryan Lindberg, Yu. V. Shvyd'ko, Alberto Lutman, Deming Shu, and Sergey Terentyev

Subjects
Materials science, business.industry, Astrophysics::High Energy Astrophysical Phenomena, Free-electron laser, Undulator, Laser, Atomic and Molecular Physics, and Optics, Electronic, Optical and Magnetic Materials, law.invention, Gain-switching, Optics, law, Optoelectronics, Spontaneous emission, business, Lasing threshold, Monochromator, Coherence (physics)
Abstract

Lasing in a hard-X-ray free-electron laser is typically seeded from noise due to the self-amplification of spontaneous emission, which limits temporal coherence and spectral characteristics. Researchers now demonstrate self-seeding using X-rays from the first half of the magnetic undulator to seed the second half via a diamond-based monochromator at angstrom wavelengths.

Published
2012
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9. Photon beamlines and diagnostics at LCLS

Author

J. Galayda, Joshua J. Turner, Y. Feng, D. McMahon, Henrik Loos, C. Gardener, T. McCarville, Daniel Ratner, K. Kishiyama, David H. Dowell, J. Welch, J. Rzepiela, Ryan Coffee, Jeff C. Robinson, Heinz-Dieter Nuhn, Zhirong Huang, R. M. Bionta, A. Miahnahri, Alan Fisher, Regina Soufli, D. Ryutov, S. Lewis, Mark A. McKernan, Stefan Moeller, K. Fong, F.-J. Decker, Stefan P. Hau-Riege, Axel Brachmann, E. Ables, Jacek Krzywinski, P. Hering, Gerald Yocky, J. Arthur, R. H. Iverson, Linda L. Ott, S. Shen, H. Tompkins, Stephan Friedrich, Marc Messerschmidt, P. Stefan, Sasha Gilevich, J. Frisch, B. White, M. J. Pivovaroff, Yuantao Ding, D. Schultz, Baxter Abraham, Juhao Wu, Jerome B. Hastings, S. A. Edstrom, T. Smith, Paul Emma, G. Hays, and G. Pile

Subjects
Physics, Nuclear and High Energy Physics, Photon, Optics, law, business.industry, Free-electron laser, Electrical engineering, Particle accelerator, business, Instrumentation, Linear particle accelerator, law.invention
Abstract

The LCLS hard X-ray Free Electron Laser at SLAC reported first lasing in April 2009. Since then two successful user runs have been completed at the two soft X-ray stations. The first hard X-ray station has started commissioning in July 2010. Beam diagnostics play an essential role for tuning the machine and delivering the requested beam properties to the users. An overview of the LCLS photon diagnostics will be presented including some selected commissioning results. Plans for future improvements and upgrades will be briefly discussed.

Published
2011
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10. First lasing and operation of an ångstrom-wavelength free-electron laser

Author

Stefan Moeller, William E. White, J. Rzepiela, Marc Messerschmidt, R. H. Iverson, Ph. Hering, Josef Frisch, R. Akre, J. Arthur, A. Miahnahri, Richard M. Bionta, Heinz-Dieter Nuhn, Y. Ding, P. Stefan, Paul Emma, Alan Fisher, Jerome B. Hastings, T. Smith, Philip H. Bucksbaum, S. A. Edstrom, D. Schultz, G. Hays, Daniel Ratner, Ryan Coffee, G. Pile, John D. Bozek, Christoph Bostedt, F.-J. Decker, Gerald Yocky, Henrik Loos, Zhirong Huang, David H. Dowell, J. Galayda, Joshua J. Turner, Axel Brachmann, Sasha Gilevich, J. Welch, Juhao Wu, and H. Tompkins

Subjects
Physics, Brightness, business.industry, Orders of magnitude (temperature), Astrophysics::High Energy Astrophysical Phenomena, Self-amplified spontaneous emission, Free-electron laser, Laser, Atomic and Molecular Physics, and Optics, Electronic, Optical and Magnetic Materials, law.invention, SACLA, Wavelength, Optics, law, Physics::Accelerator Physics, Optoelectronics, business, Lasing threshold
Abstract

The Linac Coherent Light Source free-electron laser has now achieved coherent X-ray generation down to a wavelength of 1.2 A and at a brightness that is nearly ten orders of magnitude higher than conventional synchrotrons. Researchers detail the first operation and beam characteristics of the system, which give hope for imaging at atomic spatial and temporal scales.

Published
2010
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11. The E166 experiment: Development of an undulator-based polarized positron source for the international linear collider

Author

David Walz, W. M. Bugg, S.C. Berridge, E. Reinherz-Aronis, C. Hast, G. R. Bower, J. C. Sheppard, R. Iverson, F.-J. Decker, V. Gharibyan, T. Schweizer, R. Dollan, S. Riemann, Hermann Kolanoski, Y. Efrimenko, V. Bharadwaj, Gideon Alexander, K. P. Schüler, Thomas Lohse, Z. M. Szalata, P. Pahl, Achim Stahl, Y. Batygin, Alexander Mikhailichenko, J. Kovermann, Kirk T. McDonald, A. W. Weidemann, D. J. Scott, A. Schälicke, Gudrid Moortgat-Pick, R. Pöschl, and K. Laihem

Subjects
Physics, Antiparticle, Photon, International Linear Collider, Astrophysics::High Energy Astrophysical Phenomena, General Physics and Astronomy, Polarimeter, Particle accelerator, Undulator, law.invention, Nuclear physics, Positron, law, Physics::Accelerator Physics, ddc:530, High Energy Physics::Experiment, Circular polarization
Abstract

A longitudinal polarized positron beam is foreseen for the international linear collider (ILC). A proof-of-principle experiment has been performed in the final focus test beam at SLAC to demonstrate the production of polarized positrons for implementation at the ILC. The E166 experiment uses a 1 m long helical undulator in a 46.6 GeV electron beam to produce a few MeV photons with a high degree of circular polarization. These photons are then converted in a thin target to generate longitudinally polarized e + and e −. The positron polarization is measured using a Compton transmission polarimeter. The data analysis has shown asymmetries in the expected vicinity of 3.4% and ∼1% for photons and positrons respectively and the expected positron longitudinal polarization is covering a range from 50% to 90%.

Published
2007
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13. Experimental Demonstration of a Soft X-Ray Self-Seeded Free-Electron Laser

Author

Philip Heimann, Christoph Bostedt, D. Fairley, Rafael Abela, H. Loos, G. Gassner, Uwe Flechsig, Zhirong Huang, Yuantao Ding, Heinz-Dieter Nuhn, Daniel S. Morton, F.-J. Decker, Yiping Feng, Jacek Krzywinski, Gabriel Marcus, G. Bouchard, Stefan Moeller, C. Eckman, T. Stevens, Juhao Wu, M. Boyes, K. Chow, J. B. Hastings, N. Rodes, Joshua J. Turner, D.R. Walz, Agostino Marinelli, Daniel Ratner, Alberto Lutman, C. Behrens, J. Welch, Daniele Cocco, William F. Schlotter, Dorian Bohler, J. Amann, Paul Emma, Svitozar Serkez, C. Field, N. Kelez, T. Maxwell, and Paul A. Montanez

Subjects
Physics, Brightness, business.industry, Free-electron laser, General Physics and Astronomy, Particle accelerator, Grating, Photon energy, Linear particle accelerator, law.invention, Wavelength, Optics, law, ddc:550, Optoelectronics, business, Monochromator
Abstract

The Linac Coherent Light Source has added a self-seeding capability to the soft x-ray range using a grating monochromator system. We report the demonstration of soft x-ray self-seeding with a measured resolving power of 2000–5000, wavelength stability of 10$^{−4}$, and an increase in peak brightness by a factor of 2–5 across the photon energy range of 500–1000 eV. By avoiding the need for a monochromator at the experimental station, the self-seeded beam can deliver as much as 50-fold higher brightness to users.

Published
2015
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14. Parametric exploration of intense positron beam–plasma interactions

Author

C.L. O'Connell, C. Joshi, F.-J. Decker, Brent Blue, D. Walz, C. E. Clayton, K. A. Marsh, R. Iverson, Chengkun Huang, Mark Hogan, Warren Mori, and Tom Katsouleas

Subjects
Accelerator physics, Physics, Particle accelerator, Plasma, Radius, Condensed Matter Physics, Atomic and Molecular Physics, and Optics, law.invention, Positron, Physics::Plasma Physics, law, Excited state, Physics::Accelerator Physics, Electrical and Electronic Engineering, Atomic physics, Beam (structure), Parametric statistics
Abstract

A systematic investigation of the longitudinal fields excited in a plasma by a short, dense beam of positrons is carried out using two-dimensional, cylindrical geometry, particle-in-cell code simulations. In particular, we examine the behavior of the accelerating and decelerating fields of the wakefield as a function of beam charge, radius, length, and plasma density. The parameters are chosen to be consistent with those employed in current and future experiments designed to elucidate the physics of positron beam–plasma interactions.

Published
2003
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15. Helicity-correlated systematics for SLAC Experiment E158

Author

F.-J. Decker, Gordon D. Cates, M. Woods, O. Saxton, K. Bega, Stephen M. Rock, J. Turner, E. W. Hughes, J.E. Clendenin, P.L. Anthony, Axel Brachmann, P. Mastromarino, D. Relyea, T. Fieguth, T. B. Humensky, K. S. Kumar, Yu. G. Kolomensky, Z. M. Szalata, G.M. Jones, and C. Arroyo

Subjects
Physics, Elastic scattering, Nuclear and High Energy Physics, Beam diameter, business.industry, Electron, Laser, Linear particle accelerator, law.invention, Optics, Nuclear Energy and Engineering, law, Cathode ray, Physics::Accelerator Physics, M squared, Electrical and Electronic Engineering, Møller scattering, business
Abstract

Experiment E158 at the Stanford Linear Accelerator Center (SLAC) will make the first measurement of parity violation in Moller scattering. The left-right cross-section asymmetry in the elastic scattering of a 45-GeV polarized electron beam with unpolarized electrons in a liquid hydrogen target will be measured to an accuracy of better than 10/sup -8/, with the expected Standard Model asymmetry being approximately 10/sup -7/. Because helicity-correlated (left-right) charge and position asymmetries in the electron beam can give rise to systematic errors in the measurement, great care must be given to beam monitoring and control. We have developed beam current monitors that measure the charge per pulse at the 3 /spl times/ 10/sup -5/ level and RF cavity beam position monitors that measure the position per pulse to 1 /spl mu/m, which should allow precisions of 1 ppb and 1 nm for the final integrated charge and position asymmetries, respectively. In addition, since most helicity-correlated systematics in the electron beam can be traced back to the laser that drives the photoemission from the GaAs source cathode, we first use careful control of laser beam polarization, point-to-point imaging, and other techniques to minimize systematics. We also provide the capability of modulating in a helicity-correlated way the laser beam's intensity and position as it strikes the photocathode, allowing the implementation of active feedbacks to ensure that the average charge and position asymmetries integrate close to zero over the course of the experiment. We present this system of precision beam monitoring and control and report on its performance during a recent commissioning run, T-437 at SLAC, which demonstrated charge and position asymmetry precisions of 12 ppb and 2 nm, respectively.

Published
2002
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16. Wakefields in SLAC linac collimators

Author

M. K. Sullivan, F.-J. Decker, Alexander Novokhatski, and H. Smith

Subjects
Physics, Nuclear and High Energy Physics, Physics and Astronomy (miscellaneous), business.industry, Free-electron laser, Collimator, Particle accelerator, Surfaces and Interfaces, Radiation, Linear particle accelerator, Collimated light, law.invention, Optics, law, lcsh:QC770-798, Physics::Accelerator Physics, lcsh:Nuclear and particle physics. Atomic energy. Radioactivity, Halo, business, Beam (structure)
Abstract

When a beam travels near collimator jaws, it gets an energy loss and a transverse kick due to the backreaction of the beam field diffracted from the jaws. The effect becomes very important for an intense short bunch when a tight collimation of the background beam halo is required. In the Linac Coherent Light Source at SLAC a collimation system is used to protect the undulators from radiation due to particles in the beam halo. The halo is most likely formed from gun dark current or dark current in some of the accelerating sections. However, collimators are also responsible for the generation of wake fields. The wake field effect from the collimators not only brings an additional energy jitter and change in the trajectory of the beam, but it also rotates the beam on the phase plane, which consequently leads to a degradation of the performance of the Free Electron Laser at the Linac Coherent Light Source. In this paper, we describe a model of the wake field radiation in the SLAC linac collimators. We use the results of a numerical simulation to illustrate the model. Based on the model, we derive simple formulas for the bunch energy loss andmore » the average kick. In addition, we also present results from experimental measurements that confirm our model.« less

Published
2014
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17. Publisher’s Note: Experimental demonstration of a global dispersion-free steering correction at the new linac test facility at SLAC [Phys. Rev. ST Accel. Beams 17, 042803 (2014)]

Author

Andrea Latina, N. Lipkowitz, Erik Adli, Daniel Schulte, J. Pfingstner, and F.-J. Decker

Subjects
Nuclear physics, Physics, Nuclear and High Energy Physics, Test facility, Physics and Astronomy (miscellaneous), Dispersion (optics), lcsh:QC770-798, lcsh:Nuclear and particle physics. Atomic energy. Radioactivity, Surfaces and Interfaces, Linear particle accelerator
Published
2014
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18. Few-femtosecond time-resolved measurements of X-ray free-electron lasers

Author

H. Loos, Y. Ding, T. Maxwell, J. Frisch, Alberto Lutman, F.-J. Decker, J. Welch, Jeffrey C. Wang, C. Behrens, Patrick Krejcik, Juhao Wu, Joshua J. Turner, Minhong Wang, Valery Dolgashev, and Zhirong Huang

Subjects
Free electron model, Multidisciplinary, Materials science, Time Factors, business.industry, Lasers, X-Rays, Measure (physics), Physics::Optics, General Physics and Astronomy, Electrons, General Chemistry, Laser, General Biochemistry, Genetics and Molecular Biology, law.invention, Transverse plane, Optics, law, Shot (pellet), Femtosecond, Cathode ray, Physics::Accelerator Physics, business, Lasing threshold
Abstract

X-ray free-electron lasers, with pulse durations ranging from a few to several hundred femtoseconds, are uniquely suited for studying atomic, molecular, chemical and biological systems. Characterizing the temporal profiles of these femtosecond X-ray pulses that vary from shot to shot is not only challenging but also important for data interpretation. Here we report the time-resolved measurements of X-ray free-electron lasers by using an X-band radiofrequency transverse deflector at the Linac Coherent Light Source. We demonstrate this method to be a simple, non-invasive technique with a large dynamic range for single-shot electron and X-ray temporal characterization. A resolution of less than 1 fs root mean square has been achieved for soft X-ray pulses. The lasing evolution along the undulator has been studied with the electron trapping being observed as the X-ray peak power approaches 100 GW.

Published
2014

19. E-157: A 1.4-m-long plasma wake field acceleration experiment using a 30 GeV electron beam from the Stanford Linear Accelerator Center Linac

Author

F.-J. Decker, R. G. Hemker, Sayed Rokni, Chan Joshi, S. Lee, Warren Mori, S. Wang, Robert H. Siemann, Patric Muggli, Brent Blue, C. E. Clayton, D.R. Walz, Tom Katsouleas, P. Raimondi, S. Chattopadhyay, Wim Leemans, D. Whittum, R. H. Iverson, P. Catravas, K. A. Marsh, Mark Hogan, Eric Esarey, R.W. Assmann, and E. S. Dodd

Subjects
Physics, Beam diameter, Particle accelerator, Plasma, Electron, Condensed Matter Physics, Linear particle accelerator, law.invention, Nuclear physics, Transition radiation, Physics::Plasma Physics, law, Physics::Accelerator Physics, Plasma diagnostics, Atomic physics, Beam (structure)
Abstract

In the E-157 experiment now being conducted at the Stanford Linear Accelerator Center, a 30 GeV electron beam of 2×1010 electrons in a 0.65-mm-long bunch is propagated through a 1.4-m-long lithium plasma of density up to 2×1014 e−/cm3. The initial beam density is greater than the plasma density, and the head of the bunch expels the plasma electrons leaving behind a uniform ion channel with transverse focusing fields of up to several thousand tesla per meter. The initial transverse beam size with σ=50–100 μm is larger than the matched size of 5 μm resulting in up to three beam envelope oscillations within the plasma. Time integrated optical transition radiation is used to study the transverse beam profile immediately before and after the plasma and to characterize the transverse beam dynamics as a function of plasma density. The head of the bunch deposits energy into plasma wakes, resulting in longitudinal accelerating fields which are witnessed by the tail of the same bunch. A time-resolved Cherenkov imag...

Published
2000
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20. Model-Independent Beam Dynamics Analysis

Author

F.-J. Decker, M. Minty, Y. Yan, Gennady Stupakov, Chenchen Wang, Frank Zimmermann, Karl Bane, J. Irwin, and Yunhai Cai

Subjects
Physics, Mathematical analysis, General Physics and Astronomy, Noise floor, law.invention, Matrix (mathematics), law, Position (vector), Singular value decomposition, Physics::Accelerator Physics, M squared, Atomic physics, Collider, Eigenvalues and eigenvectors, Beam (structure)
Abstract

Using a singular value decomposition of a beam line matrix, composed of many beam position measurements for a large number of pulses, together with the measurement of pulse-by-pulse beam properties or machine attributes, the contributions of each variable to the beam centroid motion can be identified with a greatly improved resolution. The eigenvalues above the noise floor determine the number of significant physical variables. This method is applicable to storage rings, linear accelerators, and any system involving a number of sources and a larger number of sensors with unknown correlations. Applications are presented from the Stanford Linear Collider. {copyright} {ital 1999} {ital The American Physical Society}

Published
1999
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21. Proposal for a one GeV plasma wakefield acceleration experiment at SLAC

Author

Robert H. Siemann, G.H. Wang, C. E. Clayton, R.W. Assmann, F.-J. Decker, D.H. Whittum, Tom Katsouleas, Sayed Rokni, K. A. Marsh, Chan Joshi, Seung Lee, Warren Mori, Wim Leemans, R. Iverson, Tor Raubenheimer, Pisin Chen, P. Raimondi, Subhasis Chattopadhyay, and D. Walz

Subjects
Physics, Nuclear physics, Nuclear and High Energy Physics, Acceleration, Physics::Plasma Physics, Physics::Accelerator Physics, High Energy Physics::Experiment, Plasma, Plasma acceleration, Instrumentation, Beam (structure), Order of magnitude
Abstract

A plasma-based wakefield acceleration experiment E-157 has been approved at SLAC to study acceleration of parts of an SLC bunch by up to 1 GeV/m over a length of 1 m. A single SLC bunch is used to both induce wakefields in the 1 m long plasma and to witness the resulting beam acceleration. The experiment will explore and further develop the techniques that are needed to apply high-gradient plasma wakefield acceleration to large-scale accelerators. The 1 m length of the experiment is about two orders of magnitude larger than for other high gradient plasma wakefield acceleration experiments and the 1 GeV/m accelerating gradient is roughly ten times larger than that achieved with conventional metallic structures. Using existing SLAC facilities, the experiment will study high gradient acceleration at the forefront of advanced accelerator research.

Published
1998
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22. Plasma lens experiment at the final focus test beam

Author

R. Iverson, P. Raimondi, Tom Katsouleas, Kazuhisa Nakajima, D. D. Meyerhofer, D. Walz, Andrew M. Sessler, David B. Cline, Wim Leemans, A. Ogata, S. Masuda, A. W. Weidemann, P. Kwok, Pisin Chen, W. Craddock, and F.-J. Decker

Subjects
Physics, Nuclear and High Energy Physics, business.industry, Particle accelerator, Plasma, Linear particle accelerator, law.invention, Lens (optics), Optics, Test beam, law, Physics::Accelerator Physics, Focus (optics), business, Instrumentation, Beam (structure)
Abstract

The proposed plasma lens experiment at the Final focus Test Beam (FFTB) facility of the Stanford Linear Accelerator Center (Chen et al. SLAC, 1997) [1] has been approved by the adminstration. The experiment would allow the examination of plasma focusing devices for particle beams in the parameter regime of interest to future high-energy colliders. It is expected to lead to compact plasma lens designs capable of focusing the beam to unprecedented small spot sizes.

Published
1998
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23. Femtosecond x-ray pulse characterization in free-electron lasers using a cross-correlation technique

Author

Juhao Wu, C. Field, F. Zhou, F.-J. Decker, Jacek Krzywinski, J. Welch, Josef Frisch, Zhirong Huang, H. Loos, Y. Ding, C Feng, and P. Emma

Subjects
Physics, Femtosecond pulse shaping, business.industry, General Physics and Astronomy, Pulse duration, Laser, law.invention, Pulse (physics), Full width at half maximum, Optics, law, Femtosecond, business, Ultrashort pulse, Bandwidth-limited pulse
Abstract

We report the first measurements of x-ray single-pulse duration and two-pulse separation at the Linac Coherent Light Source using a cross-correlation technique involving x rays and electrons. An emittance-spoiling foil is adopted as a very simple and effective method to control the output x-ray pulse. A minimum pulse duration of about 3 fs full width at half maximum has been measured together with a controllable pulse separation (delay) between two pulses. This technique provides critical temporal diagnostics for x-ray experiments such as x-ray pump-probe studies. DOI: 10.1103/PhysRevLett.109.254802

Published
2012

24. High-brightness electron beam evolution following laser-based cleaning of a photocathode

Author

Sasha Gilevich, Joshua J. Turner, F.-J. Decker, R. H. Iverson, P. Stefan, F. Zhou, Axel Brachmann, and Paul Emma

Subjects
Physics, Nuclear and High Energy Physics, Physics and Astronomy (miscellaneous), business.industry, Surfaces and Interfaces, Electron, Laser, Photocathode, Cathode, Linear particle accelerator, law.invention, Optics, law, Cathode ray, lcsh:QC770-798, lcsh:Nuclear and particle physics. Atomic energy. Radioactivity, Thermal emittance, Quantum efficiency, business
Abstract

Laser-based techniques have been widely used for cleaning metal photocathodes to increase quantum efficiency (QE). However, the impact of laser cleaning on cathode uniformity and thereby on electron beam quality are less understood. We are evaluating whether this technique can be applied to revive photocathodes used for high-brightness electron sources in advanced x-ray free-electron laser (FEL) facilities, such as the Linac Coherent Light Source (LCLS) at the SLAC National Accelerator Laboratory. The laser-based cleaning was applied to two separate areas of the current LCLS photocathode on July 4 and July 26, 2011, respectively. The QE was increased by 8--10 times upon the laser cleaning. Since the cleaning, routine operation has exhibited a slow evolution of the QE improvement and comparatively rapid improvement of transverse emittance, with a factor of 3 QE enhancement over five months, and a significant emittance improvement over the initial 2--3 weeks following the cleaning. Currently, the QE of the LCLS photocathode is holding constant at about $1.2\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}$, with a normalized injector emittance of about $0.3\text{ }\text{ }\ensuremath{\mu}\mathrm{m}$ for a 150-pC bunch charge. With the proper procedures, the laser-cleaning technique appears to be a viable tool to revive the LCLS photocathode. We present observations and analyses for the QE and emittance evolution in time following the laser-based cleaning of the LCLS photocathode, and comparison to the previous studies, the measured thermal emittance versus the QE and comparison to the theoretical model.

Published
2012
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25. A stability of LCLS linac modulators

Author

B. Morris, F.-J Decker, M. Nguyen, and A. Krasnykh

Subjects
Engineering, Modulation, law, business.industry, Electrical engineering, Electronic engineering, Particle accelerator, business, Pulse-width modulation, Linear particle accelerator, law.invention
Abstract

Information concerning to a stability of LCLS RF linac modulators is allocated in this paper. In general a “pulse-to-pulse” modulator stability (and RF phase as well) is acceptable for the LCLS commission and FEL programs. Further modulator stability improvements are possible and approaches are discussed based on our experimental results.

Published
2012
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26. PEP-II Status and Outlook

Author

Christoph Steier, A. Kulikov, F.-J. Decker, J.T. Seeman, M.E. Biagini, Zisman, J. Nelson, Martin Donald, S. D. Ecklund, Berkeley Lbl, R. H. Iverson, M. K. Sullivan, Joshua J. Turner, Patrick Krejcik, Alexander Novokhatski, A. Fisher, I. Reichel, T. Meyer, H.U. Wienands, and R.L. Holtzapple

Subjects
Nuclear physics, Physics, Reliability (semiconductor), Luminosity (scattering theory), business.industry, Detector, Electrical engineering, business
Abstract

PEP-II/BABAR are presently in their second physics run. With machine and detector performance and reliability at an all-time high, almost 51 fb{sup -1} have been integrated by BABAR up to mid-October 2001. PEP-II luminosity has reached 4.4 x 10{sup 33} cm{sup -2} s{sup -1} and our highest monthly delivered luminosity has been above 6 pb{sup -1}, exceeding the performance parameters given in the PEP-II CDR by almost 50%. The increase compared to the first run in 2000 has been achieved by a combination of beam-current increase and beam-size decrease. In this paper we will summarize the PEP-II performance and the present limitations as well as our plans to further increase machine performance.

Published
2012
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27. Precise Measurement of the Left-Right Cross Section Asymmetry inZBoson Production bye+e−Collisions

Author

R. E. Cassell, P.E. Rensing, T. H. Burnett, C. C. Young, R. Cowan, M. Nussbaum, R. Kajikawa, S. J. Yellin, G. H. Zapalac, S. Sen, L. S. Osborne, Y. Hasegawa, J.P. Venuti, Roberto Dell'Orso, N.M. Krishna, J. Va'vra, C.J.S. Damerell, G. M. Bilei, G. R. Bower, R. Ben-David, James Shank, Andrea Castro, J. Ma, H. L. Lynch, S. Hedges, J. Rothberg, I. Abt, J. Zhou, G. B. Word, R. King, A. P. Waite, J. Duboscq, M. Swartz, A. S. Johnson, C. Y. Prescott, O. Bardon, C. Baltay, M. Carpinelli, H. Masuda, C. Fan, T.J. Pavel, P. C. Rowson, H. Yuta, U. Nauenberg, B. A. Schumm, R. Frey, S. De Simone, T. Maruyama, R. Steiner, D. Su, T. Schalk, Wit Busza, S. Gonzalez, T. Gillman, F. J. Decker, J. Huber, J. R. Johnson, B. Camanzi, Shinzo Suzuki, M. Piccolo, M. Langston, O. H. Saxton, G. Mancinelli, H. R. Band, David O. Caldwell, E. Torrence, H. A. Neal, P. N. Burrows, R. Prepost, J. Wyss, Dario Bisello, T. Nagamine, T. Bienz, R. K. Yamamoto, R. Cotton, P.F. Jacques, L. Pescara, X. Liu, D.C. Schultz, P. Emma, S. S. Hertzbach, J. Quigley, J. D. Turk, J. J. Russell, Y. C. Du, T. Takahashi, K. Furuno, A. Sugiyama, R. S. Panvini, Fred Wickens, C. Zeitlin, A. Seiden, D. Aston, Stephen Robert Wagner, Y. Iwasaki, T. L. Usher, Henry W. Kendall, J. S. Whitaker, D. Calloway, T. Limberg, R. A. Johnson, R. Messner, D. G. Coyne, R. Castaldi, H. Park, E. Church, J. A. Lauber, T. Junk, Alberto Benvenuti, U. Schneekloth, B. Mours, L. S. Rochester, H. Kawahara, E. Vella, J. E. Brau, A. Calcaterra, M. D. Hildreth, D. C. Williams, G. Muller, H. M. Steiner, F. Suekane, Brian Meadows, R. R. Kofler, D. J. Sherden, Stephen Watts, D. W. G. S. Leith, I. M. Peruzzi, E. W. Hughes, S. H. Williams, E. L. Garwin, Martin Breidenbach, S. Dasu, M. Kalelkar, Rafe Schindler, M.B. Barakat, W. J. Wisniewski, Robert Wilson, R.D. Elia, G. E. Gladding, J. A. Coller, K. T. Pitts, V. Cook, R. de Sangro, H. O. Cohn, G. Hallewell, J. R. Bogart, G. D. Punkar, R.J. Plano, S. Manly, J. M. Yamartino, M. Woods, R. W. Zdarko, M.E. King, J. A. Snyder, R. Dubois, P. Stamer, J. F. McGowan, A. Lath, Yeong-Dae Kwon, T. Barklow, M. H. Kelsey, K.G. Baird, David A. Williams, A. K. McKemey, G. Blaylock, S. Willocq, W. W. Ash, Michael Sokoloff, Joseph Izen, T. Bolton, Gilbert Shapiro, E. L. Hart, S. R. Smith, T. W. Reeves, Koji Abe, Nicola Bacchetta, Thomas W. Markiewicz, Piero Giorgio Verdini, Giancarlo Mantovani, G. Baranko, H. Hwang, D. G. Hitlin, E. Mazzucato, S. L. White, A.B. d'Oliveira, C. Simopoulos, F. E. Taylor, A. Lu, M. G. Strauss, L. Piemontese, Enrico Pieroni, J. F. Labs, M. E. Huffer, A. O. Bazarko, M. Cavalli-Sforza, B. N. Ratcliff, D. L. Burke, W. M. Bugg, P. De Simone, Michael H. Shaevitz, M. Loreti, K.C. Moffeit, R. S. Kroeger, A. W. Weidemann, J. A. Jaros, P. M. Mockett, I. Karliner, Dominik Müller, B. I. Eisenstein, A. Szumilo, M. J. Fero, and C. Vannini

Subjects
Physics, Particle physics, Cabibbo–Kobayashi–Maskawa matrix, media_common.quotation_subject, Electron–positron annihilation, Hadron, General Physics and Astronomy, Elementary particle, Weinberg angle, Asymmetry, Nuclear physics, Particle decay, TheoryofComputation_ANALYSISOFALGORITHMSANDPROBLEMCOMPLEXITY, media_common, Boson
Abstract

We present a precise measurement of the left-right cross section asymmetry ([ital A][sub [ital L][ital R]]) for [ital Z] boson production by [ital e][sup +][ital e][sup [minus]] collisions. The measurement was performed at a center-of-mass energy of 91.26 GeV with the SLD detector at the SLAC Linear Collider (SLC). The luminosity-weighted average polarization of the SLC electron beam was (63.0[plus minus]1.1)%. Using a sample of 49 392 [ital Z] decays, we measure [ital A][sub [ital L][ital R]] to be 0.1628[plus minus]0.0071(stat)[plus minus]0.0028(syst) which determines the effective weak mixing angle to be sin[sup 2][theta][sub [ital W]][sup eff]=0.2292[plus minus]0.0009(stat) [plus minus]0.0004(syst).

Published
1994
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28. First Results of the LCLS Laser-Heater System

Author

H. Loos, Heinz-Dieter Nuhn, P. Emma, A. Brachmann, R. Carr, F.-J. Decker, B. Poling, Y. Levashov, Ph. Hering, A. Miahnahri, Simone Spampinati, David Dowell, R.F. Boyce, Z. Huang, S. A. Edstrom, Sasha Gilevich, R. H. Iverson, Daniel Ratner, J.C. Frisch, Y. Ding, and G. Hays

Subjects
Physics, business.industry, Particle accelerator, Undulator, Laser, Linear particle accelerator, law.invention, Optics, law, Cathode ray, Physics::Accelerator Physics, Chicane, business, Lasing threshold, Beam (structure)
Abstract

The Linac Coherent Light Source (LCLS) is an x-ray Free-Electron Laser (FEL) project that has just achieved its first lasing at 1.5 {angstrom} radiation wavelength. The very bright electron beam required to drive this FEL is susceptible to a microbunching instability in the magnetic bunch compressors that may increase the slice energy spread beyond the FEL tolerance. To control the slice energy spread and to suppress the microbunching instability, a laser heater (LH) system is installed in the LCLS injector area at 135 MeV, right before the RF deflector that is used for the time-resolved electron diagnostics. This unique component is used to add a small level of intrinsic energy spread to the electron beam in order to Landau damp the microbunching instability before it potentially breaks up the high brightness electron beam. The system was fully installed and tested in the fall of 2008, and effects of heating on the electron beam and the x-ray FEL were studied during the 2009 commissioning period. The laser heater system is composed of a 4-dipole chicane; a 9-period, planar, permanent-magnet, adjustable-gap undulator at the center of the chicane; one OTR screen on each side of the undulator for electron/laser spatial alignment; and more » an IR laser (up to 15-MW power) which co-propagates with the electron beam inside the undulator generating a 758-nm energy modulation along the bunch. The final two dipoles of the 4-dipole chicane time-smear this modulation leaving only a thermal-like intrinsic energy spread within the bunch. Table 1 lists the main parameters for this system. The very bright electron beam required for an x-ray free-electron laser (FEL), such as the LCLS, is susceptible to a microbunching instability in the magnetic bunch compressors, prior to the FEL undulator. The uncorrelated electron energy spread in the LCLS can be increased by an order of magnitude to provide strong Landau damping against the instability without degrading the FEL performance. To this end, a 'laser-heater' system has been installed in the LCLS injector, which modulates the energy of a 135-MeV electron bunch with an IR laser beam in a short undulator, enclosed within a four-dipole chicane. The last half of the chicane time-smears the energy modulation leaving an effective thermal energy spread increase. We present the first commissioning results of this system, its operational issues, its impact on the microbunching instability, and finally its effect on the FEL performance. « less

Published
2011
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29. A Proposal for Study of Structure and Dynamics of Energy/Matter Based on Production of Gamma-Ray at SLAC Facility

Author

F.-J. Decker, Kipt Kharkov, B. Shramenko, U Cornell, Anatoly Krasnykh, and M. Perelstein

Subjects
Physics, Nuclear physics, Antiparticle, Positron, Antimatter, Dark matter, Gamma ray, Cosmic ray, Elementary particle, Lepton
Abstract

The success of this proposal will open new areas of Chemistry with antimatter: (1) new chemical dynamics; (2) exclusive production of parent ions by energy-tuning the positrons; (3) formation of antimatter compounds; (4) nano- and microscopic imaging of molecules, cells, and tumors (5) multi-positron systems and their thermodynamics and chemical kinetics. Also with o-Ps and p-Ps physics including speculations of dark mater (PAMELA & ATIC reported excesses in the e{sup +}e{sup -} cosmic rays).

Published
2011
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30. First measurement of the left-right cross section asymmetry inZboson production bye+e−collisions

Author

J. Duboscq, Tadayuki Takahashi, S. Bethke, W. T. Emmet, R. Dolin, R. King, J. Hodgson, Sridhara Dasu, G.J. Tappern, S. A. Wickert, P. C. Rowson, R. J. Stephenson, R. Prepost, D. Pripstein, M. Tecchio, J. E. Brau, A. W. Weidemann, A. Yim, P.F. Jacques, T. Dean, T. H. Burnett, Amitabh Lath, H. Yuta, L. Piemontese, B. F. Wadsworth, Enrico Pieroni, E. Hyatt, L. Mathys, R. H. Schindler, A. Szumilo, G. Tarnopolsky, M. Settles, Roberto Battiston, R. Davis, A. Nuttall, T. A. Hodges, R. R. Kofler, D. Walz, A. V. Kulikov, R. Messner, J. F. Labs, J.P. Venuti, P. E.L. Clarke, A. Rothenberg, D. Mansour, R. Kroeger, D. Axen, A. Gioumousis, W. A. Majid, H. J. Hargis, C.J.S. Damerell, R. J. Wilson, D. J. Sherden, A. K. Honma, E. Vella, A. I. Mincer, S. H. Williams, A. O. Bazarko, D. D. Durrett, O. Chamberlain, J. A. Coller, E. L. Garwin, John Fox, N. Toge, D. Horelick, C. Baltay, M. D. Hildreth, F. Bird, C. Y. Prescott, D. W. G. S. Leith, P. Coyle, H. Cutler, C. J. Oram, H. Masuda, H. L. Lynch, R. Bell, J. Olsen, Nicholas Walker, J. Escalera, A.P.T. Palounek, Roberto Dell'Orso, L. P. Robertson, Melody A. Swartz, D. Su, D. Warner, R. R. Larsen, H. Petersen, J. Clendenin, A. Astbury, R. J. Morrison, G. A. Beer, D. R. Freytag, R. H. Siemann, Philip Burrows, T. Hansl-Kozanecka, S. McHugh, A. L. Shoup, R. E. Cassell, P.E. Rensing, T. Shimomura, M. Piccolo, M. J. Fox, J. Rothberg, D.C. Schultz, R. Langstaff, I. Abt, L. Pescara, I. Stockdale, G. Stewart, H. Shaw, P. De Simone, J. M. Yamartino, D. J. Mellor, M. Langston, O. Bardon, R.L. English, R. Watt, V. Cook, R. Cotton, M. Petradza, P. M. Mockett, V. Ashford, P. Saez, Michael S. Witherell, R. de Sangro, K. Skarpaas, R. C. Hilomen, T. Fieguth, Wit Busza, J. Flynn, D. Aston, G. Mancinelli, Patrick Krejcik, R. Rinta, T. W. Reeves, Rino Castaldi, H. O. Cohn, M. Loreti, V. Ziemann, K. Hasegawa, Richard Keeler, S. Kaiser, S. Hedges, J. L. Turner, G. Agnew, Joseph Izen, B. Burgess, L. Servoli, R. J. Belcinski, K. K. Young, John Scott Whitaker, X. Liu, Koji Abe, P. Kunz, S. S. Hertzbach, W. Craddock, G. Hallewell, I. Karliner, M. G. Strauss, Dominik Müller, J. Carr, D. Calloway, A. Lu, C. C. Young, B. I. Eisenstein, Elliot Hughes, T. Junk, M. Carpinelli, S. Bougerolle, G. D. Punkar, J. D. Turk, D. L. Burke, H. O. Ogren, R. W. Williams, W. M. Bugg, U. Schneekloth, S.C. Berridge, A. Disco, D. L. Hale, G. M. Bilei, G. R. Bower, James Shank, R. Cowan, Andrea Castro, Henry W. Kendall, L. Chen, R. K. Jobe, R. Ossa, Gunther Haller, O. H. Saxton, E. Rutz, C. Alber, T. Schalk, F. Toevs, J. J. Thaler, R. Claus, J. Fujimoto, D. P. Gurd, R. K. Yamamoto, P. Stiles, M. Minty, B. N. Ratcliff, S. Ecklund, D. Chambers, J. Wyss, C. Simopoulos, H. R. Band, J. A. Lauber, A. Santocchia, C. Yee, E. Erdos, P. Poffenberger, Yeong-Dae Kwon, G. Blaylock, D. A. Forbush, J. Huber, D. Kharakh, B. Camanzi, W. W. Ash, W. J. Wisniewski, F. Suekane, R.J. Plano, P. E. Stamer, M. Schneider, G. Eigen, M. Turcotte, M. D. Woodly, P. Zucchelli, G. Putallaz, M. J. Haney, A. Bean, C. G. Arroyo, B.L. Byers, W. Baker, W. L. Spence, S.R. Smith, Fred Wickens, A. P. Waite, J. T. Seeman, C. Zeitlin, T. Lyons, T. Bienz, N. Phinney, Martin Breidenbach, S. J. Yellin, L. Lintern, L. Paffrath, A. Calcaterra, K.G. Baird, R. Berger, C. Jako, N.M. Krishna, R.D. Elia, G. E. Gladding, S. Manly, I. M. Peruzzi, E. Mazzucato, R. Pitthan, Hyun-Chul Kim, J. J. Russell, Y. C. Du, W. Dunwoodie, David A. Williams, Y. Au, A. K. McKemey, R. F. Boyce, M. Zolotorev, J. A. Snyder, K. T. Pitts, L.S. Osborne, G. H. Zapalac, H. Tang, A. S. Johnson, M. Kalelkar, J. Frisch, R. S. Panvini, J. Hoeflich, T. Maruyama, B. A. Schumm, K.C. Moffeit, G. B. Word, G. E. Schultz, R. A. Johnson, R. Steiner, P. Antilogus, M. H. Kelsey, J. C. Sheppard, S. Gonzalez, M. Gaillard, A. Snyder, Thomas W. Markiewicz, S. L. Cartwright, K. Furuno, A. D. Yeremian, T. Gillman, V. Nesterov, H.J. Kang, Maurizio Biasini, T. Himel, Marc Ross, Yukio Hasegawa, H. A. Neal, Shiro Suzuki, D. F. Alzofon, Michele Gallinaro, D. Cords, M. Kowitt, A.K.S. Santha, R. W. Zdarko, D. G. Coyne, D. C. Williams, T. Bolton, C. Vannini, G. Oxoby, R. Shypit, Gilbert Shapiro, R. Verdier, E. L. Hart, D. Peters, A. Seiden, R. W. Downing, M. Z. Tahar, P. J. Emma, Alberto Benvenuti, H. Kawahara, C. Fan, T.J. Pavel, R. Frey, S. De Simone, F. Perrier, J. R. Johnson, R. Kajikawa, G. Mundy, V. Hamilton, P. D. Acton, P. C. Kim, H. M. Steiner, L. Rosenson, P. Schenk, K. M. Fortune, Richard Dubois, R. Ben-David, J. Zhou, M. Woods, J. Va’vra, M. Nordby, T. E. Browder, B. Mours, T. Nagamine, Nicola Bacchetta, D. McCormick, D. O. Caldwell, J. F. McGowan, G. Mazaheri, A. Sugiyama, M. Nussbaum, G. Mueller, Stephen Watts, F. Barrera, S. Jones, F. E. Taylor, M.E. Huffer, J. R. Bogart, J. Ferrie, R. Sobie, A. Mazzucato, Piero Giorgio Verdini, M. Pauluzzi, J. Ma, L. Camilleri, J. D. Richman, G. B. Chadwick, T. Weber, Giancarlo Mantovani, H. Hwang, Michael J. Fero, S.St. Lorant, J.I. Friedman, L.S. Rochester, Y. Iwasaki, T. L. Usher, M. Cavalli-Sforza, B. T. Meadows, D. G. Hitlin, F. J. Decker, M. D. Sokoloff, E.N. Spencer, H. Park, M. H. Shaevitz, G. Baranko, T. Limberg, D. R. Rust, G. R. Mason, S. L. White, D. Nelson, P. Raimondi, S. L. Shapiro, P. Rankin, A.B. d'Oliveira, U. Nauenberg, J. Harrison, Chris Adolphsen, R. Blumberg, F. Dejongh, Dario Bisello, and M. Klein

Subjects
Physics, Particle physics, Cabibbo–Kobayashi–Maskawa matrix, media_common.quotation_subject, General Physics and Astronomy, Elementary particle, Production (computer science), Beam polarization, Asymmetry, Energy (signal processing), media_common, Standard Model, Boson
Abstract

We present the first measurement of the left-right cross section asymmetry (${\mathit{A}}_{\mathit{L}\mathit{R}}$) for Z boson production by ${\mathit{e}}^{+}$${\mathit{e}}^{\mathrm{\ensuremath{-}}}$ collisions. The measurement was performed at a center-of-mass energy of 91.55 GeV with the SLD detector at the SLAC Linear Collider which utilized a longitudinally polarized electron beam. The average beam polarization was (22.4\ifmmode\pm\else\textpm\fi{}0.6)%. Using a sample of 10 224 Z decays, we measure ${\mathit{A}}_{\mathit{L}\mathit{R}}$ to be 0.100\ifmmode\pm\else\textpm\fi{}0.044(stat)\ifmmode\pm\else\textpm\fi{}0.004(syst), which determines the effective weak mixing angle to be ${\mathrm{sin}}^{2}$${\mathrm{\ensuremath{\theta}}}_{\mathit{W}}^{\mathit{e}\mathit{f}\mathit{f}}$=0.2378 \ifmmode\pm\else\textpm\fi{}0.0056(stat)\ifmmode\pm\else\textpm\fi{}0.0005(syst).

Published
1993
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31. Measurements of the linac coherent light source laser heater and its impact on the x-ray free-electron laser performance

Author

Josef Frisch, Daniel Ratner, Joshua J. Turner, Heinz-Dieter Nuhn, Y. Ding, David H. Dowell, Dao Xiang, Henrik Loos, Ph. Hering, Zhirong Huang, Sasha Gilevich, Paul Emma, Juhao Wu, Gennady Stupakov, R. H. Iverson, J. Welch, G. Hays, Axel Brachmann, William E. White, A. Miahnahri, and F.-J. Decker

Subjects
Physics, Nuclear and High Energy Physics, Physics and Astronomy (miscellaneous), business.industry, Free-electron laser, Surfaces and Interfaces, Electron, Undulator, Laser, Linear particle accelerator, law.invention, Optics, law, Cathode ray, lcsh:QC770-798, Physics::Accelerator Physics, lcsh:Nuclear and particle physics. Atomic energy. Radioactivity, Landau damping, business, Beam (structure)
Abstract

The very bright electron beam required for an x-ray free-electron laser (FEL), such as the linac coherent light source (LCLS), is susceptible to a microbunching instability in the magnetic bunch compressors, prior to the FEL undulator. The uncorrelated electron energy spread in the LCLS can be increased by an order of magnitude to provide strong Landau damping against the instability without degrading the FEL performance. To this end, a ``laser-heater'' system has been installed in the LCLS injector, which modulates the energy of a 135-MeV electron bunch with an IR-laser beam in a short undulator, enclosed within a four-dipole chicane. In this paper, we report detailed measurements of laser-heater-induced energy spread, including the unexpected self-heating phenomenon when the laser energy is very low. We discuss the suppression of the microbunching instability with the laser heater and its impact on the x-ray FEL performance. We also present the analysis of these experimental results and develop a three-dimensional longitudinal space charge model to explain the self-heating effect.

Published
2010
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32. Transverse emittance and current of multi-GeV trapped electrons in a plasma wakefield accelerator

Author

Warren Mori, F.-J. Decker, Wei Lu, Tom Katsouleas, Samuel Martins, Patric Muggli, D.R. Walz, Robert H. Siemann, I. Blumenfeld, Erdem Oz, R. H. Iverson, K. A. Marsh, Neil Kirby, C. E. Clayton, C. Joshi, Rasmus Ischebeck, Meng Zhou, Chengkun Huang, and Mark Hogan

Subjects
Physics, Nuclear and High Energy Physics, Physics and Astronomy (miscellaneous), Bubble, Particle accelerator, Surfaces and Interfaces, Electron, Plasma, Plasma acceleration, law.invention, Nuclear physics, Transverse plane, law, lcsh:QC770-798, Physics::Accelerator Physics, lcsh:Nuclear and particle physics. Atomic energy. Radioactivity, Thermal emittance, Current (fluid), Atomic physics
Abstract

Multi-GeV trapped electron bunches in a plasma wakefield accelerator (PWFA) are observed with normalized transverse emittance divided by peak current, {epsilon}{sub N,x}/I{sub t}, below the level of 0.2 {micro}m/kA. A theoretical model of the trapped electron emittance, developed here, indicates that emittance scales inversely with the square root of the plasma density in the nonlinear 'bubble' regime of the PWFA. This model and simulations indicate that the observed values of {epsilon}{sub N,x}/I{sub t} result from multi-GeV trapped electron bunches with emittances of a few {micro}m and multi-kA peak currents.

Published
2009
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33. Measurements and modeling of coherent synchrotron radiation and its impact on the Linac Coherent Light Source electron beam

Author

F.-J. Decker, Joshua J. Turner, Yuantao Ding, Paul Emma, David H. Dowell, R. H. Iverson, J. Welch, Gennady Stupakov, Karl Bane, Daniel Ratner, Juhao Wu, Zhirong Huang, C. Limborg-Deprey, H. Loos, Heinz-Dieter Nuhn, and Josef Frisch

Subjects
Physics, Nuclear and High Energy Physics, Physics and Astronomy (miscellaneous), business.industry, Bremsstrahlung, Free-electron laser, Synchrotron radiation, Particle accelerator, Surfaces and Interfaces, Laser, Electromagnetic radiation, Linear particle accelerator, law.invention, Optics, law, lcsh:QC770-798, Physics::Accelerator Physics, lcsh:Nuclear and particle physics. Atomic energy. Radioactivity, Thermal emittance, business
Abstract

In order to reach the high peak current required for an x-ray free electron laser, two separate magnetic dipole chicanes are used in the Linac Coherent Light Source (LCLS) accelerator to compress the electron bunch length in stages. In these bunch compressors, coherent synchrotron radiation (CSR) can be emitted either by a short electron bunch or by any longitudinal density modulation that may be on the bunch. In this paper, we report detailed measurements of the CSR-induced energy loss and transverse emittance growth in these compressors. Good agreement is found between the experimental results and multi-particle tracking studies. We also describe direct observations of CSR at optical wavelengths and compare with analytical models based on beam microbunching.

Published
2009
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34. Measurements and simulations of ultralow emittance and ultrashort electron beams in the linac coherent light source

Author

J. Welch, Heinz-Dieter Nuhn, Y. Ding, Henrik Loos, William E. White, Daniel Ratner, Ph. Hering, Zhirong Huang, Josef Frisch, Joshua J. Turner, David H. Dowell, Axel Brachmann, R. H. Iverson, Sasha Gilevich, Paul Emma, F.-J. Decker, G. Hays, A. Miahnahri, and Jihuai Wu

Subjects
Physics, business.industry, General Physics and Astronomy, Particle accelerator, Electron, Laser, Linear particle accelerator, law.invention, Nuclear physics, Wavelength, Optics, law, Femtosecond, Physics::Accelerator Physics, Thermal emittance, business, Beam (structure)
Abstract

The Linac Coherent Light Source (LCLS) is an x-ray free-electron laser project presently in a commissioning phase at the SLAC National Accelerator Laboratory. We report here on very low-emittance measurements made at low bunch charge, and a few femtosecond bunch length produced by the LCLS bunch compressors. Start-to-end simulations associated with these beam parameters show the possibilities of generating hundreds of GW at 1.5 A x-ray wavelength and nearly a single longitudinally coherent spike at 1.5 nm with 2-fs duration.

Published
2009

35. Erratum: Observation of the Bottomonium Ground State in the DecayΥ(3S)→γηb[Phys. Rev. Lett.101, 071801 (2008)]

Author

B. Aubert, M. Bona, Y. Karyotakis, J. P. Lees, V. Poireau, E. Prencipe, X. Prudent, V. Tisserand, J. Garra Tico, E. Grauges, L. Lopez, A. Palano, M. Pappagallo, G. Eigen, B. Stugu, L. Sun, G. S. Abrams, M. Battaglia, D. N. Brown, R. N. Cahn, R. G. Jacobsen, L. T. Kerth, Yu. G. Kolomensky, G. Lynch, I. L. Osipenkov, M. T. Ronan, K. Tackmann, T. Tanabe, C. M. Hawkes, N. Soni, A. T. Watson, H. Koch, T. Schroeder, D. Walker, D. J. Asgeirsson, B. G. Fulsom, C. Hearty, T. S. Mattison, J. A. McKenna, M. Barrett, A. Khan, V. E. Blinov, A. D. Bukin, A. R. Buzykaev, V. P. Druzhinin, V. B. Golubev, A. P. Onuchin, S. I. Serednyakov, Yu. I. Skovpen, E. P. Solodov, K. Yu. Todyshev, M. Bondioli, S. Curry, I. Eschrich, D. Kirkby, A. J. Lankford, P. Lund, M. Mandelkern, E. C. Martin, D. P. Stoker, S. Abachi, C. Buchanan, J. W. Gary, F. Liu, O. Long, B. C. Shen, G. M. Vitug, Z. Yasin, L. Zhang, V. Sharma, C. Campagnari, T. M. Hong, D. Kovalskyi, M. A. Mazur, J. D. Richman, T. W. Beck, A. M. Eisner, C. J. Flacco, C. A. Heusch, J. Kroseberg, W. S. Lockman, A. J. Martinez, T. Schalk, B. A. Schumm, A. Seiden, M. G. Wilson, L. O. Winstrom, C. H. Cheng, D. A. Doll, B. Echenard, F. Fang, D. G. Hitlin, I. Narsky, T. Piatenko, F. C. Porter, R. Andreassen, G. Mancinelli, B. T. Meadows, K. Mishra, M. D. Sokoloff, P. C. Bloom, W. T. Ford, A. Gaz, J. F. Hirschauer, M. Nagel, U. Nauenberg, J. G. Smith, K. A. Ulmer, S. R. Wagner, R. Ayad, A. Soffer, W. H. Toki, R. J. Wilson, D. D. Altenburg, E. Feltresi, A. Hauke, H. Jasper, M. Karbach, J. Merkel, A. Petzold, B. Spaan, K. Wacker, M. J. Kobel, W. F. Mader, R. Nogowski, K. R. Schubert, R. Schwierz, A. Volk, D. Bernard, G. R. Bonneaud, E. Latour, M. Verderi, P. J. Clark, S. Playfer, J. E. Watson, M. Andreotti, D. Bettoni, C. Bozzi, R. Calabrese, A. Cecchi, G. Cibinetto, P. Franchini, E. Luppi, M. Negrini, A. Petrella, L. Piemontese, V. Santoro, R. Baldini-Ferroli, A. Calcaterra, R. de Sangro, G. Finocchiaro, S. Pacetti, P. Patteri, I. M. Peruzzi, M. Piccolo, M. Rama, A. Zallo, A. Buzzo, R. Contri, M. Lo Vetere, M. M. Macri, M. R. Monge, S. Passaggio, C. Patrignani, E. Robutti, A. Santroni, S. Tosi, K. S. Chaisanguanthum, M. Morii, A. Adametz, J. Marks, S. Schenk, U. Uwer, V. Klose, H. M. Lacker, D. J. Bard, P. D. Dauncey, J. A. Nash, M. Tibbetts, P. K. Behera, X. Chai, M. J. Charles, U. Mallik, J. Cochran, H. B. Crawley, L. Dong, W. T. Meyer, S. Prell, E. I. Rosenberg, A. E. Rubin, Y. Y. Gao, A. V. Gritsan, Z. J. Guo, C. K. Lae, N. Arnaud, J. Béquilleux, A. D’Orazio, M. Davier, J. Firmino da Costa, G. Grosdidier, A. Höcker, V. Lepeltier, F. Le Diberder, A. M. Lutz, S. Pruvot, P. Roudeau, M. H. Schune, J. Serrano, V. Sordini, A. Stocchi, G. Wormser, D. J. Lange, D. M. Wright, I. Bingham, J. P. Burke, C. A. Chavez, J. R. Fry, E. Gabathuler, R. Gamet, D. E. Hutchcroft, D. J. Payne, C. Touramanis, A. J. Bevan, C. K. Clarke, K. A. George, F. Di Lodovico, R. Sacco, M. Sigamani, G. Cowan, H. U. Flaecher, D. A. Hopkins, S. Paramesvaran, F. Salvatore, A. C. Wren, C. L. Davis, A. G. Denig, M. Fritsch, W. Gradl, G. Schott, K. E. Alwyn, D. Bailey, R. J. Barlow, Y. M. Chia, C. L. Edgar, G. Jackson, G. D. Lafferty, T. J. West, J. I. Yi, J. Anderson, C. Chen, A. Jawahery, D. A. Roberts, G. Simi, J. M. Tuggle, C. Dallapiccola, X. Li, E. Salvati, S. Saremi, R. Cowan, D. Dujmic, P. H. Fisher, G. Sciolla, M. Spitznagel, F. Taylor, R. K. Yamamoto, M. Zhao, P. M. Patel, S. H. Robertson, A. Lazzaro, V. Lombardo, F. Palombo, J. M. Bauer, L. Cremaldi, R. Godang, R. Kroeger, D. A. Sanders, D. J. Summers, H. W. Zhao, M. Simard, P. Taras, F. B. Viaud, H. Nicholson, G. De Nardo, L. Lista, D. Monorchio, G. Onorato, C. Sciacca, G. Raven, H. L. Snoek, C. P. Jessop, K. J. Knoepfel, J. M. LoSecco, W. F. Wang, G. Benelli, L. A. Corwin, K. Honscheid, H. Kagan, R. Kass, J. P. Morris, A. M. Rahimi, J. J. Regensburger, S. J. Sekula, Q. K. Wong, N. L. Blount, J. Brau, R. Frey, O. Igonkina, J. A. Kolb, M. Lu, R. Rahmat, N. B. Sinev, D. Strom, J. Strube, E. Torrence, G. Castelli, N. Gagliardi, M. Margoni, M. Morandin, M. Posocco, M. Rotondo, F. Simonetto, R. Stroili, C. Voci, P. del Amo Sanchez, E. Ben-Haim, H. Briand, G. Calderini, J. Chauveau, P. David, L. Del Buono, O. Hamon, Ph. Leruste, J. Ocariz, A. Perez, J. Prendki, S. Sitt, L. Gladney, M. Biasini, R. Covarelli, E. Manoni, C. Angelini, G. Batignani, S. Bettarini, M. Carpinelli, A. Cervelli, F. Forti, M. A. Giorgi, A. Lusiani, G. Marchiori, M. Morganti, N. Neri, E. Paoloni, G. Rizzo, J. J. Walsh, D. Lopes Pegna, C. Lu, J. Olsen, A. J. S. Smith, A. V. Telnov, F. Anulli, E. Baracchini, G. Cavoto, D. del Re, E. Di Marco, R. Faccini, F. Ferrarotto, F. Ferroni, M. Gaspero, P. D. Jackson, L. Li Gioi, M. A. Mazzoni, S. Morganti, G. Piredda, F. Polci, F. Renga, C. Voena, M. Ebert, T. Hartmann, H. Schröder, R. Waldi, T. Adye, B. Franek, E. O. Olaiya, F. F. Wilson, S. Emery, M. Escalier, L. Esteve, S. F. Ganzhur, G. Hamel de Monchenault, W. Kozanecki, G. Vasseur, Ch. Yèche, M. Zito, X. R. Chen, H. Liu, W. Park, M. V. Purohit, R. M. White, J. R. Wilson, M. T. Allen, D. Aston, R. Bartoldus, P. Bechtle, J. F. Benitez, K. Bertsche, Y. Cai, R. Cenci, J. P. Coleman, M. R. Convery, F. J. Decker, J. C. Dingfelder, J. Dorfan, G. P. Dubois-Felsmann, W. Dunwoodie, S. Ecklund, R. Erickson, R. C. Field, A. Fisher, J. Fox, A. M. Gabareen, S. J. Gowdy, M. T. Graham, P. Grenier, C. Hast, W. R. Innes, R. Iverson, J. Kaminski, M. H. Kelsey, H. Kim, P. Kim, M. L. Kocian, A. Kulikov, D. W. G. S. Leith, S. Li, B. Lindquist, S. Luitz, V. Luth, H. L. Lynch, D. B. MacFarlane, H. Marsiske, R. Messner, D. R. Muller, H. Neal, S. Nelson, A. Novokhatski, C. P. O’Grady, I. Ofte, A. Perazzo, M. Perl, B. N. Ratcliff, C. Rivetta, A. Roodman, A. A. Salnikov, R. H. Schindler, J. Schwiening, J. Seeman, A. Snyder, D. Su, M. K. Sullivan, K. Suzuki, S. K. Swain, J. M. Thompson, J. Va’vra, D. Van Winkle, A. P. Wagner, M. Weaver, C. A. West, U. Wienands, W. J. Wisniewski, M. Wittgen, W. Wittmer, D. H. Wright, H. W. Wulsin, Y. Yan, A. K. Yarritu, K. Yi, G. Yocky, C. C. Young, V. Ziegler, P. R. Burchat, A. J. Edwards, S. A. Majewski, T. S. Miyashita, B. A. Petersen, L. Wilden, S. Ahmed, M. S. Alam, J. A. Ernst, B. Pan, M. A. Saeed, S. B. Zain, S. M. Spanier, B. J. Wogsland, R. Eckmann, J. L. Ritchie, A. M. Ruland, C. J. Schilling, R. F. Schwitters, B. W. Drummond, J. M. Izen, X. C. Lou, F. Bianchi, D. Gamba, M. Pelliccioni, M. Bomben, L. Bosisio, C. Cartaro, G. Della Ricca, L. Lanceri, L. Vitale, V. Azzolini, N. Lopez-March, F. Martinez-Vidal, D. A. Milanes, A. Oyanguren, J. Albert, Sw. Banerjee, B. Bhuyan, H. H. F. Choi, K. Hamano, R. Kowalewski, M. J. Lewczuk, I. M. Nugent, J. M. Roney, R. J. Sobie, T. J. Gershon, P. F. Harrison, J. Ilic, T. E. Latham, G. B. Mohanty, H. R. Band, X. Chen, S. Dasu, K. T. Flood, Y. Pan, M. Pierini, R. Prepost, C. O. Vuosalo, and S. L. Wu

Subjects
Physics, Nuclear physics, Particle decay, General Physics and Astronomy, Ground state
Published
2009
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36. Measurement of thee+e−→bb¯Cross Section betweens=10.54and 11.20 GeV

Author

B. Aubert, M. Bona, Y. Karyotakis, J. P. Lees, V. Poireau, E. Prencipe, X. Prudent, V. Tisserand, J. Garra Tico, E. Grauges, L. Lopez, A. Palano, M. Pappagallo, G. Eigen, B. Stugu, L. Sun, G. S. Abrams, M. Battaglia, D. N. Brown, R. N. Cahn, R. G. Jacobsen, L. T. Kerth, Yu. G. Kolomensky, G. Lynch, I. L. Osipenkov, M. T. Ronan, K. Tackmann, T. Tanabe, C. M. Hawkes, N. Soni, A. T. Watson, H. Koch, T. Schroeder, D. Walker, D. J. Asgeirsson, B. G. Fulsom, C. Hearty, T. S. Mattison, J. A. McKenna, M. Barrett, A. Khan, V. E. Blinov, A. D. Bukin, A. R. Buzykaev, V. P. Druzhinin, V. B. Golubev, A. P. Onuchin, S. I. Serednyakov, Yu. I. Skovpen, E. P. Solodov, K. Yu. Todyshev, M. Bondioli, S. Curry, I. Eschrich, D. Kirkby, A. J. Lankford, P. Lund, M. Mandelkern, E. C. Martin, D. P. Stoker, S. Abachi, C. Buchanan, J. W. Gary, F. Liu, O. Long, B. C. Shen, G. M. Vitug, Z. Yasin, L. Zhang, V. Sharma, C. Campagnari, T. M. Hong, D. Kovalskyi, M. A. Mazur, J. D. Richman, T. W. Beck, A. M. Eisner, C. J. Flacco, C. A. Heusch, J. Kroseberg, W. S. Lockman, A. J. Martinez, T. Schalk, B. A. Schumm, A. Seiden, M. G. Wilson, L. O. Winstrom, C. H. Cheng, D. A. Doll, B. Echenard, F. Fang, D. G. Hitlin, I. Narsky, T. Piatenko, F. C. Porter, R. Andreassen, G. Mancinelli, B. T. Meadows, K. Mishra, M. D. Sokoloff, P. C. Bloom, W. T. Ford, A. Gaz, J. F. Hirschauer, M. Nagel, U. Nauenberg, J. G. Smith, K. A. Ulmer, S. R. Wagner, R. Ayad, A. Soffer, W. H. Toki, R. J. Wilson, D. D. Altenburg, E. Feltresi, A. Hauke, H. Jasper, M. Karbach, J. Merkel, A. Petzold, B. Spaan, K. Wacker, M. J. Kobel, W. F. Mader, R. Nogowski, K. R. Schubert, R. Schwierz, A. Volk, D. Bernard, G. R. Bonneaud, E. Latour, M. Verderi, P. J. Clark, S. Playfer, J. E. Watson, M. Andreotti, D. Bettoni, C. Bozzi, R. Calabrese, A. Cecchi, G. Cibinetto, P. Franchini, E. Luppi, M. Negrini, A. Petrella, L. Piemontese, V. Santoro, R. Baldini-Ferroli, A. Calcaterra, R. de Sangro, G. Finocchiaro, S. Pacetti, P. Patteri, I. M. Peruzzi, M. Piccolo, M. Rama, A. Zallo, A. Buzzo, R. Contri, M. Lo Vetere, M. M. Macri, M. R. Monge, S. Passaggio, C. Patrignani, E. Robutti, A. Santroni, S. Tosi, K. S. Chaisanguanthum, M. Morii, A. Adametz, J. Marks, S. Schenk, U. Uwer, V. Klose, H. M. Lacker, D. J. Bard, P. D. Dauncey, J. A. Nash, M. Tibbetts, P. K. Behera, X. Chai, M. J. Charles, U. Mallik, J. Cochran, H. B. Crawley, L. Dong, W. T. Meyer, S. Prell, E. I. Rosenberg, A. E. Rubin, Y. Y. Gao, A. V. Gritsan, Z. J. Guo, C. K. Lae, N. Arnaud, J. Béquilleux, A. D’Orazio, M. Davier, J. Firmino da Costa, G. Grosdidier, A. Höcker, V. Lepeltier, F. Le Diberder, A. M. Lutz, S. Pruvot, P. Roudeau, M. H. Schune, J. Serrano, V. Sordini, A. Stocchi, G. Wormser, D. J. Lange, D. M. Wright, I. Bingham, J. P. Burke, C. A. Chavez, J. R. Fry, E. Gabathuler, R. Gamet, D. E. Hutchcroft, D. J. Payne, C. Touramanis, A. J. Bevan, C. K. Clarke, K. A. George, F. Di Lodovico, R. Sacco, M. Sigamani, G. Cowan, H. U. Flaecher, D. A. Hopkins, S. Paramesvaran, F. Salvatore, A. C. Wren, C. L. Davis, A. G. Denig, M. Fritsch, W. Gradl, G. Schott, K. E. Alwyn, D. Bailey, R. J. Barlow, Y. M. Chia, C. L. Edgar, G. Jackson, G. D. Lafferty, T. J. West, J. I. Yi, J. Anderson, C. Chen, A. Jawahery, D. A. Roberts, G. Simi, J. M. Tuggle, C. Dallapiccola, X. Li, E. Salvati, S. Saremi, R. Cowan, D. Dujmic, P. H. Fisher, G. Sciolla, M. Spitznagel, F. Taylor, R. K. Yamamoto, M. Zhao, P. M. Patel, S. H. Robertson, A. Lazzaro, V. Lombardo, F. Palombo, J. M. Bauer, L. Cremaldi, R. Godang, R. Kroeger, D. A. Sanders, D. J. Summers, H. W. Zhao, M. Simard, P. Taras, F. B. Viaud, H. Nicholson, G. De Nardo, L. Lista, D. Monorchio, G. Onorato, C. Sciacca, G. Raven, H. L. Snoek, C. P. Jessop, K. J. Knoepfel, J. M. LoSecco, W. F. Wang, G. Benelli, L. A. Corwin, K. Honscheid, H. Kagan, R. Kass, J. P. Morris, A. M. Rahimi, J. J. Regensburger, S. J. Sekula, Q. K. Wong, N. L. Blount, J. Brau, R. Frey, O. Igonkina, J. A. Kolb, M. Lu, R. Rahmat, N. B. Sinev, D. Strom, J. Strube, E. Torrence, G. Castelli, N. Gagliardi, M. Margoni, M. Morandin, M. Posocco, M. Rotondo, F. Simonetto, R. Stroili, C. Voci, P. del Amo Sanchez, E. Ben-Haim, H. Briand, G. Calderini, J. Chauveau, P. David, L. Del Buono, O. Hamon, Ph. Leruste, J. Ocariz, A. Perez, J. Prendki, S. Sitt, L. Gladney, M. Biasini, R. Covarelli, E. Manoni, C. Angelini, G. Batignani, S. Bettarini, M. Carpinelli, A. Cervelli, F. Forti, M. A. Giorgi, A. Lusiani, G. Marchiori, M. Morganti, N. Neri, E. Paoloni, G. Rizzo, J. J. Walsh, D. Lopes Pegna, C. Lu, J. Olsen, A. J. S. Smith, A. V. Telnov, F. Anulli, E. Baracchini, G. Cavoto, D. del Re, E. Di Marco, R. Faccini, F. Ferrarotto, F. Ferroni, M. Gaspero, P. D. Jackson, L. Li Gioi, M. A. Mazzoni, S. Morganti, G. Piredda, F. Polci, F. Renga, C. Voena, M. Ebert, T. Hartmann, H. Schröder, R. Waldi, T. Adye, B. Franek, E. O. Olaiya, F. F. Wilson, S. Emery, M. Escalier, L. Esteve, S. F. Ganzhur, G. Hamel de Monchenault, W. Kozanecki, G. Vasseur, Ch. Yèche, M. Zito, X. R. Chen, H. Liu, W. Park, M. V. Purohit, R. M. White, J. R. Wilson, M. T. Allen, D. Aston, R. Bartoldus, P. Bechtle, J. F. Benitez, K. Bertsche, Y. Cai, R. Cenci, J. P. Coleman, M. R. Convery, F. J. Decker, J. C. Dingfelder, J. Dorfan, G. P. Dubois-Felsmann, W. Dunwoodie, S. Ecklund, R. Erickson, R. C. Field, A. Fisher, J. Fox, A. M. Gabareen, S. J. Gowdy, M. T. Graham, P. Grenier, C. Hast, W. R. Innes, R. Iverson, J. Kaminski, M. H. Kelsey, H. Kim, P. Kim, M. L. Kocian, A. Kulikov, D. W. G. S. Leith, S. Li, B. Lindquist, S. Luitz, V. Luth, H. L. Lynch, D. B. MacFarlane, H. Marsiske, R. Messner, D. R. Muller, H. Neal, S. Nelson, A. Novokhatski, C. P. O’Grady, I. Ofte, A. Perazzo, M. Perl, B. N. Ratcliff, C. Rivetta, A. Roodman, A. A. Salnikov, R. H. Schindler, J. Schwiening, J. Seeman, A. Snyder, D. Su, M. K. Sullivan, K. Suzuki, S. K. Swain, J. M. Thompson, J. Va’vra, D. Van Winkle, A. P. Wagner, M. Weaver, C. A. West, U. Wienands, W. J. Wisniewski, M. Wittgen, W. Wittmer, D. H. Wright, H. W. Wulsin, Y. Yan, A. K. Yarritu, K. Yi, G. Yocky, C. C. Young, V. Ziegler, P. R. Burchat, A. J. Edwards, S. A. Majewski, T. S. Miyashita, B. A. Petersen, L. Wilden, S. Ahmed, M. S. Alam, J. A. Ernst, B. Pan, M. A. Saeed, S. B. Zain, S. M. Spanier, B. J. Wogsland, R. Eckmann, J. L. Ritchie, A. M. Ruland, C. J. Schilling, R. F. Schwitters, B. W. Drummond, J. M. Izen, X. C. Lou, F. Bianchi, D. Gamba, M. Pelliccioni, M. Bomben, L. Bosisio, C. Cartaro, G. Della Ricca, L. Lanceri, L. Vitale, V. Azzolini, N. Lopez-March, F. Martinez-Vidal, D. A. Milanes, A. Oyanguren, J. Albert, Sw. Banerjee, B. Bhuyan, H. H. F. Choi, K. Hamano, R. Kowalewski, M. J. Lewczuk, I. M. Nugent, J. M. Roney, R. J. Sobie, T. J. Gershon, P. F. Harrison, J. Ilic, T. E. Latham, G. B. Mohanty, H. R. Band, X. Chen, S. Dasu, K. T. Flood, Y. Pan, M. Pierini, R. Prepost, C. O. Vuosalo, and S. L. Wu

Subjects
Physics, Particle physics, Range (particle radiation), 010308 nuclear & particles physics, Root (chord), General Physics and Astronomy, BaBar experiment, 01 natural sciences, law.invention, Nuclear physics, Cross section (physics), law, 0103 physical sciences, 010306 general physics, Collider, Energy (signal processing), Bar (unit)
Abstract

We report e;{+}e;{-}-->bb[over ] cross section measurements by the BABAR experiment performed during an energy scan in the range of 10.54 to 11.20 GeV at the SLAC PEP-II e;{+}e;{-} collider. A total relative error of about 5% is reached in more than 300 center-of-mass energy steps, separated by about 5 MeV. These measurements can be used to derive precise information on the parameters of the Upsilon(10860) and Upsilon(11020) resonances. In particular we show that their widths may be smaller than previously measured.

Published
2009
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37. Emittance and Current of Electrons Trapped in a Plasma Wakefield Accelerator

Author

N. Kirby, I. Blumenfeld, C. E. Clayton, F. J. Decker, M. J. Hogan, C. Huang, R. Ischebeck, R. H. Iverson, C. Joshi, T. Katsouleas, W. Lu, K. A. Marsh, S. Martins, W. B. Mori, P. Muggli, E. Oz, R. H. Siemann, D. R. Walz, M. Zhou, Carl B. Schroeder, Wim Leemans, and Eric Esarey

Subjects
Physics, Particle accelerator, Trapping, Plasma, Electron, Plasma acceleration, Linear particle accelerator, law.invention, Nuclear physics, Transverse plane, Physics::Plasma Physics, law, Physics::Accelerator Physics, Thermal emittance, Atomic physics
Abstract

In recent experiments plasma electrons became trapped in a plasma wakefield accelerator (PWFA). The transverse size of these trapped electrons on a downstream diagnostic yields an upper limit measurement of transverse normalized emittance divided by peak current, eN,x/I. The lowest upper limit for eN,x/I measured in the experiment is 1.3⋅10−10 m/A.

Published
2009
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38. Measurement of the Decelerating Wake in a Plasma Wakefield Accelerator

Author

I. Blumenfeld, C. E. Clayton, F. J. Decker, M. J. Hogan, C. Huang, R. Ischebeck, R. H. Iverson, C. Joshi, T. Katsouleas, N. Kirby, W. Lu, K. A. Marsh, W. B. Mori, P. Muggli, E. Oz, R. H. Siemann, D. R. Walz, M. Zhou, Carl B. Schroeder, Wim Leemans, and Eric Esarey

Subjects
Physics, Particle accelerator, Electron, Plasma, Wake, Plasma acceleration, Linear particle accelerator, law.invention, Nuclear physics, Acceleration, Physics::Plasma Physics, law, Cathode ray, Physics::Accelerator Physics
Abstract

Recent experiments at SLAC have shown that high gradient acceleration of electrons is achievable in meter scale plasmas. Results from these experiments show that the wakefield is sensitive to parameters in the electron beam which drives it. In the experiment the bunch lengths were varied systematically at constant charge. The effort to extract a measurement of the decelerating wake from the maximum energy loss of the electron beam is discussed.

Published
2009
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39. Measurement of the e;{+}e;{-}--bb[over ] Cross Section between sqrt[s]=10.54 and 11.20 GeV

Author

B, Aubert, M, Bona, Y, Karyotakis, J P, Lees, V, Poireau, E, Prencipe, X, Prudent, V, Tisserand, J, Garra Tico, E, Grauges, L, Lopez, A, Palano, M, Pappagallo, G, Eigen, B, Stugu, L, Sun, G S, Abrams, M, Battaglia, D N, Brown, R N, Cahn, R G, Jacobsen, L T, Kerth, Yu G, Kolomensky, G, Lynch, I L, Osipenkov, M T, Ronan, K, Tackmann, T, Tanabe, C M, Hawkes, N, Soni, A T, Watson, H, Koch, T, Schroeder, D, Walker, D J, Asgeirsson, B G, Fulsom, C, Hearty, T S, Mattison, J A, McKenna, M, Barrett, A, Khan, V E, Blinov, A D, Bukin, A R, Buzykaev, V P, Druzhinin, V B, Golubev, A P, Onuchin, S I, Serednyakov, Yu I, Skovpen, E P, Solodov, K Yu, Todyshev, M, Bondioli, S, Curry, I, Eschrich, D, Kirkby, A J, Lankford, P, Lund, M, Mandelkern, E C, Martin, D P, Stoker, S, Abachi, C, Buchanan, J W, Gary, F, Liu, O, Long, B C, Shen, G M, Vitug, Z, Yasin, L, Zhang, V, Sharma, C, Campagnari, T M, Hong, D, Kovalskyi, M A, Mazur, J D, Richman, T W, Beck, A M, Eisner, C J, Flacco, C A, Heusch, J, Kroseberg, W S, Lockman, A J, Martinez, T, Schalk, B A, Schumm, A, Seiden, M G, Wilson, L O, Winstrom, C H, Cheng, D A, Doll, B, Echenard, F, Fang, D G, Hitlin, I, Narsky, T, Piatenko, F C, Porter, R, Andreassen, G, Mancinelli, B T, Meadows, K, Mishra, M D, Sokoloff, P C, Bloom, W T, Ford, A, Gaz, J F, Hirschauer, M, Nagel, U, Nauenberg, J G, Smith, K A, Ulmer, S R, Wagner, R, Ayad, A, Soffer, W H, Toki, R J, Wilson, D D, Altenburg, E, Feltresi, A, Hauke, H, Jasper, M, Karbach, J, Merkel, A, Petzold, B, Spaan, K, Wacker, M J, Kobel, W F, Mader, R, Nogowski, K R, Schubert, R, Schwierz, A, Volk, D, Bernard, G R, Bonneaud, E, Latour, M, Verderi, P J, Clark, S, Playfer, J E, Watson, M, Andreotti, D, Bettoni, C, Bozzi, R, Calabrese, A, Cecchi, G, Cibinetto, P, Franchini, E, Luppi, M, Negrini, A, Petrella, L, Piemontese, V, Santoro, R, Baldini-Ferroli, A, Calcaterra, R, de Sangro, G, Finocchiaro, S, Pacetti, P, Patteri, I M, Peruzzi, M, Piccolo, M, Rama, A, Zallo, A, Buzzo, R, Contri, M, Lo Vetere, M M, Macri, M R, Monge, S, Passaggio, C, Patrignani, E, Robutti, A, Santroni, S, Tosi, K S, Chaisanguanthum, M, Morii, A, Adametz, J, Marks, S, Schenk, U, Uwer, V, Klose, H M, Lacker, D J, Bard, P D, Dauncey, J A, Nash, M, Tibbetts, P K, Behera, X, Chai, M J, Charles, U, Mallik, J, Cochran, H B, Crawley, L, Dong, W T, Meyer, S, Prell, E I, Rosenberg, A E, Rubin, Y Y, Gao, A V, Gritsan, Z J, Guo, C K, Lae, N, Arnaud, J, Béquilleux, A, D'Orazio, M, Davier, J, Firmino da Costa, G, Grosdidier, A, Höcker, V, Lepeltier, F, Le Diberder, A M, Lutz, S, Pruvot, P, Roudeau, M H, Schune, J, Serrano, V, Sordini, A, Stocchi, G, Wormser, D J, Lange, D M, Wright, I, Bingham, J P, Burke, C A, Chavez, J R, Fry, E, Gabathuler, R, Gamet, D E, Hutchcroft, D J, Payne, C, Touramanis, A J, Bevan, C K, Clarke, K A, George, F, Di Lodovico, R, Sacco, M, Sigamani, G, Cowan, H U, Flaecher, D A, Hopkins, S, Paramesvaran, F, Salvatore, A C, Wren, C L, Davis, A G, Denig, M, Fritsch, W, Gradl, G, Schott, K E, Alwyn, D, Bailey, R J, Barlow, Y M, Chia, C L, Edgar, G, Jackson, G D, Lafferty, T J, West, J I, Yi, J, Anderson, C, Chen, A, Jawahery, D A, Roberts, G, Simi, J M, Tuggle, C, Dallapiccola, X, Li, E, Salvati, S, Saremi, R, Cowan, D, Dujmic, P H, Fisher, G, Sciolla, M, Spitznagel, F, Taylor, R K, Yamamoto, M, Zhao, P M, Patel, S H, Robertson, A, Lazzaro, V, Lombardo, F, Palombo, J M, Bauer, L, Cremaldi, R, Godang, R, Kroeger, D A, Sanders, D J, Summers, H W, Zhao, M, Simard, P, Taras, F B, Viaud, H, Nicholson, G, De Nardo, L, Lista, D, Monorchio, G, Onorato, C, Sciacca, G, Raven, H L, Snoek, C P, Jessop, K J, Knoepfel, J M, Losecco, W F, Wang, G, Benelli, L A, Corwin, K, Honscheid, H, Kagan, R, Kass, J P, Morris, A M, Rahimi, J J, Regensburger, S J, Sekula, Q K, Wong, N L, Blount, J, Brau, R, Frey, O, Igonkina, J A, Kolb, M, Lu, R, Rahmat, N B, Sinev, D, Strom, J, Strube, E, Torrence, G, Castelli, N, Gagliardi, M, Margoni, M, Morandin, M, Posocco, M, Rotondo, F, Simonetto, R, Stroili, C, Voci, P, Del Amo Sanchez, E, Ben-Haim, H, Briand, G, Calderini, J, Chauveau, P, David, L, Del Buono, O, Hamon, Ph, Leruste, J, Ocariz, A, Perez, J, Prendki, S, Sitt, L, Gladney, M, Biasini, R, Covarelli, E, Manoni, C, Angelini, G, Batignani, S, Bettarini, M, Carpinelli, A, Cervelli, F, Forti, M A, Giorgi, A, Lusiani, G, Marchiori, M, Morganti, N, Neri, E, Paoloni, G, Rizzo, J J, Walsh, D, Lopes Pegna, C, Lu, J, Olsen, A J S, Smith, A V, Telnov, F, Anulli, E, Baracchini, G, Cavoto, D, Del Re, E, Di Marco, R, Faccini, F, Ferrarotto, F, Ferroni, M, Gaspero, P D, Jackson, L, Li Gioi, M A, Mazzoni, S, Morganti, G, Piredda, F, Polci, F, Renga, C, Voena, M, Ebert, T, Hartmann, H, Schröder, R, Waldi, T, Adye, B, Franek, E O, Olaiya, F F, Wilson, S, Emery, M, Escalier, L, Esteve, S F, Ganzhur, G, Hamel de Monchenault, W, Kozanecki, G, Vasseur, Ch, Yèche, M, Zito, X R, Chen, H, Liu, W, Park, M V, Purohit, R M, White, J R, Wilson, M T, Allen, D, Aston, R, Bartoldus, P, Bechtle, J F, Benitez, K, Bertsche, Y, Cai, R, Cenci, J P, Coleman, M R, Convery, F J, Decker, J C, Dingfelder, J, Dorfan, G P, Dubois-Felsmann, W, Dunwoodie, S, Ecklund, R, Erickson, R C, Field, A, Fisher, J, Fox, A M, Gabareen, S J, Gowdy, M T, Graham, P, Grenier, C, Hast, W R, Innes, R, Iverson, J, Kaminski, M H, Kelsey, H, Kim, P, Kim, M L, Kocian, A, Kulikov, D W G S, Leith, S, Li, B, Lindquist, S, Luitz, V, Luth, H L, Lynch, D B, Macfarlane, H, Marsiske, R, Messner, D R, Muller, H, Neal, S, Nelson, A, Novokhatski, C P, O'Grady, I, Ofte, A, Perazzo, M, Perl, B N, Ratcliff, C, Rivetta, A, Roodman, A A, Salnikov, R H, Schindler, J, Schwiening, J, Seeman, A, Snyder, D, Su, M K, Sullivan, K, Suzuki, S K, Swain, J M, Thompson, J, Va'vra, D, Van Winkle, A P, Wagner, M, Weaver, C A, West, U, Wienands, W J, Wisniewski, M, Wittgen, W, Wittmer, D H, Wright, H W, Wulsin, Y, Yan, A K, Yarritu, K, Yi, G, Yocky, C C, Young, V, Ziegler, P R, Burchat, A J, Edwards, S A, Majewski, T S, Miyashita, B A, Petersen, L, Wilden, S, Ahmed, M S, Alam, J A, Ernst, B, Pan, M A, Saeed, S B, Zain, S M, Spanier, B J, Wogsland, R, Eckmann, J L, Ritchie, A M, Ruland, C J, Schilling, R F, Schwitters, B W, Drummond, J M, Izen, X C, Lou, F, Bianchi, D, Gamba, M, Pelliccioni, M, Bomben, L, Bosisio, C, Cartaro, G, Della Ricca, L, Lanceri, L, Vitale, V, Azzolini, N, Lopez-March, F, Martinez-Vidal, D A, Milanes, A, Oyanguren, J, Albert, Sw, Banerjee, B, Bhuyan, H H F, Choi, K, Hamano, R, Kowalewski, M J, Lewczuk, I M, Nugent, J M, Roney, R J, Sobie, T J, Gershon, P F, Harrison, J, Ilic, T E, Latham, G B, Mohanty, H R, Band, X, Chen, S, Dasu, K T, Flood, Y, Pan, M, Pierini, R, Prepost, C O, Vuosalo, and S L, Wu

Abstract

We report e;{+}e;{-}--bb[over ] cross section measurements by the BABAR experiment performed during an energy scan in the range of 10.54 to 11.20 GeV at the SLAC PEP-II e;{+}e;{-} collider. A total relative error of about 5% is reached in more than 300 center-of-mass energy steps, separated by about 5 MeV. These measurements can be used to derive precise information on the parameters of the Upsilon(10860) and Upsilon(11020) resonances. In particular we show that their widths may be smaller than previously measured.

Published
2008

40. Observation of the bottomonium ground state in the decay Upsilon(3S)--gammaetab

Author

B, Aubert, M, Bona, Y, Karyotakis, J P, Lees, V, Poireau, E, Prencipe, X, Prudent, V, Tisserand, J, Garra Tico, E, Grauges, L, Lopez, A, Palano, M, Pappagallo, G, Eigen, B, Stugu, L, Sun, G S, Abrams, M, Battaglia, D N, Brown, R N, Cahn, R G, Jacobsen, L T, Kerth, Yu G, Kolomensky, G, Lynch, I L, Osipenkov, M T, Ronan, K, Tackmann, T, Tanabe, C M, Hawkes, N, Soni, A T, Watson, H, Koch, T, Schroeder, D, Walker, D J, Asgeirsson, B G, Fulsom, C, Hearty, T S, Mattison, J A, McKenna, M, Barrett, A, Khan, V E, Blinov, A D, Bukin, A R, Buzykaev, V P, Druzhinin, V B, Golubev, A P, Onuchin, S I, Serednyakov, Yu I, Skovpen, E P, Solodov, K Yu, Todyshev, M, Bondioli, S, Curry, I, Eschrich, D, Kirkby, A J, Lankford, P, Lund, M, Mandelkern, E C, Martin, D P, Stoker, S, Abachi, C, Buchanan, J W, Gary, F, Liu, O, Long, B C, Shen, G M, Vitug, Z, Yasin, L, Zhang, V, Sharma, C, Campagnari, T M, Hong, D, Kovalskyi, M A, Mazur, J D, Richman, T W, Beck, A M, Eisner, C J, Flacco, C A, Heusch, J, Kroseberg, W S, Lockman, A J, Martinez, T, Schalk, B A, Schumm, A, Seiden, M G, Wilson, L O, Winstrom, C H, Cheng, D A, Doll, B, Echenard, F, Fang, D G, Hitlin, I, Narsky, T, Piatenko, F C, Porter, R, Andreassen, G, Mancinelli, B T, Meadows, K, Mishra, M D, Sokoloff, P C, Bloom, W T, Ford, A, Gaz, J F, Hirschauer, M, Nagel, U, Nauenberg, J G, Smith, K A, Ulmer, S R, Wagner, R, Ayad, A, Soffer, W H, Toki, R J, Wilson, D D, Altenburg, E, Feltresi, A, Hauke, H, Jasper, M, Karbach, J, Merkel, A, Petzold, B, Spaan, K, Wacker, M J, Kobel, W F, Mader, R, Nogowski, K R, Schubert, R, Schwierz, A, Volk, D, Bernard, G R, Bonneaud, E, Latour, M, Verderi, P J, Clark, S, Playfer, J E, Watson, M, Andreotti, D, Bettoni, C, Bozzi, R, Calabrese, A, Cecchi, G, Cibinetto, P, Franchini, E, Luppi, M, Negrini, A, Petrella, L, Piemontese, V, Santoro, R, Baldini-Ferroli, A, Calcaterra, R, de Sangro, G, Finocchiaro, S, Pacetti, P, Patteri, I M, Peruzzi, M, Piccolo, M, Rama, A, Zallo, A, Buzzo, R, Contri, M, Lo Vetere, M M, Macri, M R, Monge, S, Passaggio, C, Patrignani, E, Robutti, A, Santroni, S, Tosi, K S, Chaisanguanthum, M, Morii, A, Adametz, J, Marks, S, Schenk, U, Uwer, V, Klose, H M, Lacker, D J, Bard, P D, Dauncey, J A, Nash, M, Tibbetts, P K, Behera, X, Chai, M J, Charles, U, Mallik, J, Cochran, H B, Crawley, L, Dong, W T, Meyer, S, Prell, E I, Rosenberg, A E, Rubin, Y Y, Gao, A V, Gritsan, Z J, Guo, C K, Lae, N, Arnaud, J, Béquilleux, A, D'Orazio, M, Davier, J Firmino, da Costa, G, Grosdidier, A, Höcker, V, Lepeltier, F, Le Diberder, A M, Lutz, S, Pruvot, P, Roudeau, M H, Schune, J, Serrano, V, Sordini, A, Stocchi, G, Wormser, D J, Lange, D M, Wright, I, Bingham, J P, Burke, C A, Chavez, J R, Fry, E, Gabathuler, R, Gamet, D E, Hutchcroft, D J, Payne, C, Touramanis, A J, Bevan, C K, Clarke, K A, George, F, Di Lodovico, R, Sacco, M, Sigamani, G, Cowan, H U, Flaecher, D A, Hopkins, S, Paramesvaran, F, Salvatore, A C, Wren, C L, Davis, A G, Denig, M, Fritsch, W, Gradl, G, Schott, K E, Alwyn, D, Bailey, R J, Barlow, Y M, Chia, C L, Edgar, G, Jackson, G D, Lafferty, T J, West, J I, Yi, J, Anderson, C, Chen, A, Jawahery, D A, Roberts, G, Simi, J M, Tuggle, C, Dallapiccola, X, Li, E, Salvati, S, Saremi, R, Cowan, D, Dujmic, P H, Fisher, G, Sciolla, M, Spitznagel, F, Taylor, R K, Yamamoto, M, Zhao, P M, Patel, S H, Robertson, A, Lazzaro, V, Lombardo, F, Palombo, J M, Bauer, L, Cremaldi, R, Godang, R, Kroeger, D A, Sanders, D J, Summers, H W, Zhao, M, Simard, P, Taras, F B, Viaud, H, Nicholson, G, De Nardo, L, Lista, D, Monorchio, G, Onorato, C, Sciacca, G, Raven, H L, Snoek, C P, Jessop, K J, Knoepfel, J M, LoSecco, W F, Wang, G, Benelli, L A, Corwin, K, Honscheid, H, Kagan, R, Kass, J P, Morris, A M, Rahimi, J J, Regensburger, S J, Sekula, Q K, Wong, N L, Blount, J, Brau, R, Frey, O, Igonkina, J A, Kolb, M, Lu, R, Rahmat, N B, Sinev, D, Strom, J, Strube, E, Torrence, G, Castelli, N, Gagliardi, M, Margoni, M, Morandin, M, Posocco, M, Rotondo, F, Simonetto, R, Stroili, C, Voci, P, del Amo Sanchez, E, Ben-Haim, H, Briand, G, Calderini, J, Chauveau, P, David, L, Del Buono, O, Hamon, Ph, Leruste, J, Ocariz, A, Perez, J, Prendki, S, Sitt, L, Gladney, M, Biasini, R, Covarelli, E, Manoni, C, Angelini, G, Batignani, S, Bettarini, M, Carpinelli, A, Cervelli, F, Forti, M A, Giorgi, A, Lusiani, G, Marchiori, M, Morganti, N, Neri, E, Paoloni, G, Rizzo, J J, Walsh, D, Lopes Pegna, C, Lu, J, Olsen, A J S, Smith, A V, Telnov, F, Anulli, E, Baracchini, G, Cavoto, D, del Re, E, Di Marco, R, Faccini, F, Ferrarotto, F, Ferroni, M, Gaspero, P D, Jackson, L Li, Gioi, M A, Mazzoni, S, Morganti, G, Piredda, F, Polci, F, Renga, C, Voena, M, Ebert, T, Hartmann, H, Schröder, R, Waldi, T, Adye, B, Franek, E O, Olaiya, F F, Wilson, S, Emery, M, Escalier, L, Esteve, S F, Ganzhur, G Hamel, de Monchenault, W, Kozanecki, G, Vasseur, Ch, Yèche, M, Zito, X R, Chen, H, Liu, W, Park, M V, Purohit, R M, White, J R, Wilson, M T, Allen, D, Aston, R, Bartoldus, P, Bechtle, J F, Benitez, K, Bertsche, Y, Cai, R, Cenci, J P, Coleman, M R, Convery, F J, Decker, J C, Dingfelder, J, Dorfan, G P, Dubois-Felsmann, W, Dunwoodie, S, Ecklund, R, Erickson, R C, Field, A, Fisher, J, Fox, A M, Gabareen, S J, Gowdy, M T, Graham, P, Grenier, C, Hast, W R, Innes, R, Iverson, J, Kaminski, M H, Kelsey, H, Kim, P, Kim, M L, Kocian, A, Kulikov, D W G S, Leith, S, Li, B, Lindquist, S, Luitz, V, Luth, H L, Lynch, D B, Macfarlane, H, Marsiske, R, Messner, D R, Muller, H, Neal, S, Nelson, A, Novokhatski, C P, O'Grady, I, Ofte, A, Perazzo, M, Perl, B N, Ratcliff, C, Rivetta, A, Roodman, A A, Salnikov, R H, Schindler, J, Schwiening, J, Seeman, A, Snyder, D, Su, M K, Sullivan, K, Suzuki, S K, Swain, J M, Thompson, J, Va'vra, D, Van Winkle, A P, Wagner, M, Weaver, C A, West, U, Wienands, W J, Wisniewski, M, Wittgen, W, Wittmer, D H, Wright, H W, Wulsin, Y, Yan, A K, Yarritu, K, Yi, G, Yocky, C C, Young, V, Ziegler, P R, Burchat, A J, Edwards, S A, Majewski, T S, Miyashita, B A, Petersen, L, Wilden, S, Ahmed, M S, Alam, J A, Ernst, B, Pan, M A, Saeed, S B, Zain, S M, Spanier, B J, Wogsland, R, Eckmann, J L, Ritchie, A M, Ruland, C J, Schilling, R F, Schwitters, B W, Drummond, J M, Izen, X C, Lou, F, Bianchi, D, Gamba, M, Pelliccioni, M, Bomben, L, Bosisio, C, Cartaro, G, Della Ricca, L, Lanceri, L, Vitale, V, Azzolini, N, Lopez-March, F, Martinez-Vidal, D A, Milanes, A, Oyanguren, J, Albert, Sw, Banerjee, B, Bhuyan, H H F, Choi, K, Hamano, R, Kowalewski, M J, Lewczuk, I M, Nugent, J M, Roney, R J, Sobie, T J, Gershon, P F, Harrison, J, Ilic, T E, Latham, G B, Mohanty, H R, Band, X, Chen, S, Dasu, K T, Flood, Y, Pan, M, Pierini, R, Prepost, C O, Vuosalo, and S L, Wu

Abstract

We report the results of a search for the bottomonium ground state etab(1S) in the photon energy spectrum with a sample of (109+/-1) million of Upsilon(3S) recorded at the Upsilon(3S) energy with the BABAR detector at the PEP-II B factory at SLAC. We observe a peak in the photon energy spectrum at Egamma=921.2(-2.8)+2.1(stat)+/-2.4(syst) MeV with a significance of 10 standard deviations. We interpret the observed peak as being due to monochromatic photons from the radiative transition Upsilon(3S)--gammaetab(1S). This photon energy corresponds to an etab(1S) mass of 9388.9(-2.3)+3.1(stat)+/-2.7(syst) MeV/c2. The hyperfine Upsilon(1S)-etab(1S) mass splitting is 71.4(-3.1)+2.3(stat)+/-2.7(syst) MeV/c2. The branching fraction for this radiative Upsilon(3S) decay is estimated to be [4.8+/-0.5(stat)+/-1.2(syst)]x10(-4).

Published
2008

41. Halo formation and emittance growth of positron beams in plasmas

Author

D. Walz, Robert H. Siemann, Wei Lu, C. E. Clayton, C.L. O'Connell, Mark Hogan, F.-J. Decker, Brent Blue, Patric Muggli, Chengkun Huang, Tom Katsouleas, Warren Mori, Meng Zhou, and C. Joshi

Subjects
Physics, Transverse plane, Positron, Physics::Accelerator Physics, General Physics and Astronomy, Thermal emittance, Halo, Plasma, Electron, Atomic physics, Space charge, Beam (structure)
Abstract

An ultrarelativistic 28.5 GeV, 700-microm-long positron bunch is focused near the entrance of a 1.4-m-long plasma with a density n(e) between approximately equal to 10(13) and approximately equal to 5 x 10(14) cm(-3). Partial neutralization of the bunch space charge by the mobile plasma electrons results in a reduction in transverse size by a factor of approximately equal to 3 in the high emittance plane of the beam approximately equal to 1 m downstream from the plasma exit. As n(e) increases, the formation of a beam halo containing approximately 40% of the total charge is observed, indicating that the plasma focusing force is nonlinear. Numerical simulations confirm these observations. The bunch with an incoming transverse size ratio of approximately 3 and emittance ratio of approximately 5 suffers emittance growth and exits the plasma with approximately equal sizes and emittances.

Published
2007

42. Hosing Instability in the Blow-Out Regime for Plasma-Wakefield Acceleration

Author

Warren Mori, Tom Katsouleas, F.-J. Decker, I. Blumenfeld, Mark Hogan, C. E. Clayton, Erdem Oz, Rasmus Ischebeck, Chengkun Huang, Wei Lu, Meng Zhou, Neil Kirby, R. Iverson, Patric Muggli, D. Walz, S. Deng, and Chan Joshi

Subjects
Physics, General Physics and Astronomy, Acceleration (differential geometry), Plasma, Electron, Plasma acceleration, Instability, Two-stream instability, Classical mechanics, Physics::Plasma Physics, Quantum electrodynamics, Physics::Space Physics, Perturbation theory, Lepton
Abstract

The electron hosing instability in the blow-out regime of plasma-wakefield acceleration is investigated using a linear perturbation theory about the electron blow-out trajectory in Lu et al. [in Phys. Rev. Lett. 96, 165002 (2006)10.1103/PhysRevLett.96.165002]. The growth of the instability is found to be affected by the beam parameters unlike in the standard theory Whittum et al. [Phys. Rev. Lett. 67, 991 (1991)10.1103/PhysRevLett.67.991] which is strictly valid for preformed channels. Particle-in-cell simulations agree with this new theory, which predicts less hosing growth than found by the hosing theory of Whittum et al.

Published
2007
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43. Lowering the vertical emittance in the ler ring of pep-ii

Author

F.-J. Decker, Y. Nosochkov, Y.T. Yan, Yunhai Cai, and Gerald Yocky

Subjects
Coupling, Rest (physics), Physics, business.industry, Skew, Particle accelerator, Solenoid, law.invention, Optics, Nuclear magnetic resonance, law, Physics::Accelerator Physics, Thermal emittance, Beam emittance, business, Beam (structure)
Abstract

The low energy ring (LER) in the PEP-II B-Factory has a design emittance of 0.5 nm-rad in the vertical, compared to nearly 0.1 nm-rad for the HER ring. This was thought to be caused mainly by the "vertical step" of 0.89 m in the interaction region straight, where the LER beam after horizontal separation gets bend vertical so it sits on top of the HER in the rest of the ring. Since the program MAD does not easily reveal the location of the major emittance contribution, a program was written to calculate the coupled "curly H" parameter of mode 2 (mainly vertical) along z. Weighting it with the magnet bending revealed that the weak long bends inside the "vertical step" did less than 20% of the emittance growth. More than 80% comes from the last quarter of each of the adjacent arcs with strong bends. This is caused by the coupling cancellation of the solenoid starting already there with the skew quadrupoles SK5 and 6. By introducing additional skew quadrupoles in the straight instead of SK5 and 6 the emittance could be reduced by a factor of ten in simulations, but with very strong skews. Reasonable strong magnets might generate a workable compromise, since a factor of two in emittance promises 50% more luminosity in beam-beam simulations.

Published
2007
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44. Scaling of energy gain with plasma parameters in a plasma wakefield accelerator

Author

R. H. Iverson, Chan Joshi, Chengkun Huang, Mark Hogan, F.-J. Decker, Patric Muggli, I. Blumenfeld, Robert H. Siemann, C. E. Clayton, Meng Zhou, K. A. Marsh, Wei Lu, Erdem Oz, Rasmus Ischebeck, Tom Katsouleas, Warren Mori, Dieter Walz, and Neil Kirby

Subjects
Physics, Plasma parameters, Particle accelerator, Electron, Plasma, Plasma acceleration, Linear particle accelerator, law.invention, Nuclear physics, Physics::Plasma Physics, law, Physics::Accelerator Physics, Collider, Plasma stability
Abstract

We have recently demonstrating the doubling of the energy of particles of the ultra-short, ultra-relativistic electron bunches of the Stanford Linear Accelerator Center [1]. This energy doubling occurred in a plasma only 85 cm-long with a density of =2.6times1017 e-/cm-3. This milestone is the result of systematic measurements that show the scaling of the energy gain with plasma length and density, and show the reproducibility and the stability of the acceleration process. We show that the energy gain increases linearly with plasma length from 13 to 31 cm. These are key steps toward the application of beam- driven plasma accelerators or plasma wakefield accelerators (PWFA) to doubling the energy of a future linear collider without doubling its length.

Published
2007
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45. Emittance measurements of trapped electrons from a plasma wakefield accelerator

Author

Patrick Muggli, Rasmus Ischebeck, F.-J. Decker, Meng Zhou, K. A. Marsh, R. H. Iverson, Mark Hogan, Chengkun Huang, Wei Lu, M. Berry, Warren Mori, Erdem Oz, Tom Katsouleas, Neil Kirby, C. Joshi, D.R. Walz, Robert H. Siemann, C. E. Clayton, and I. Blumenfeld

Subjects
Physics, Spectrometer, Particle accelerator, Plasma, Electron, Plasma acceleration, law.invention, Nuclear physics, Physics::Plasma Physics, law, Cathode ray, Physics::Accelerator Physics, Thermal emittance, Atomic physics, Nuclear Experiment, Beam (structure)
Abstract

Recent electron beam driven plasma wakefield accelerator experiments carried out at SLAC showed trapping of plasma electrons. These trapped electrons appeared on an energy spectrometer with smaller transverse size than the beam driving the wake. A connection is made between transverse size and emittance; due to the spectrometer's resolution, this connection allows for placing an upper limit on the trapped electron emittance. The upper limit for the lowest normalized emittance measured in the experiment is 1 mm-mrad.

Published
2007
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46. Ionization-Induced Electron Trapping in Ultrarelativistic Plasma Wakes

Author

Mark Hogan, F.-J. Decker, Tom Katsouleas, P. Emma, C.L. O'Connell, Robert H. Siemann, S. Deng, C. E. Clayton, Chan Joshi, Warren Mori, Patrick Krejcik, D. K. Johnson, Meng Zhou, D. Walz, Rasmus Ischebeck, R. H. Iverson, C.D. Barnes, Chengkun Huang, Erdem Oz, I. Blumenfeld, K. A. Marsh, Patric Muggli, Wei Lu, Neil Kirby, and D. W. Auerbach

Subjects
Condensed Matter::Quantum Gases, Physics, Electron capture, General Physics and Astronomy, Plasma, Trapping, Electron, Ion, Relativistic plasma, Physics::Plasma Physics, Ionization, Physics::Accelerator Physics, Physics::Atomic Physics, Atomic physics, Ionization energy
Abstract

The onset of trapping of electrons born inside a highly relativistic, 3D beam-driven plasma wake is investigated. Trapping occurs in the transition regions of a Li plasma confined by He gas. Li plasma electrons support the wake, and higher ionization potential He atoms are ionized as the beam is focused by Li ions and can be trapped. As the wake amplitude is increased, the onset of trapping is observed. Some electrons gain up to 7.6 GeV in a 30.5 cm plasma. The experimentally inferred trapping threshold is at a wake amplitude of 36 GV/m, in good agreement with an analytical model and PIC simulations.

Published
2007
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47. Significant lifetime and background improvements in pep-ii by reducing the 3rd order chromaticity in ler with orbit bumps

Author

Yuri Nosochkov, F.-J. Decker, M. K. Sullivan, and Gerald Yocky

Subjects
Electromagnetic field, Physics, business.industry, Detector, Beat (acoustics), Nonlinear optics, Particle accelerator, law.invention, Phase change, Low energy, Optics, law, Chromaticity, business
Abstract

Orbit bumps in sextupoles are routinely used for tuning the luminosity in the PEP-II B-Factory. Anti-symmetric bumps at a pair of identical sextupoles separated by -I section generate the net dispersion, while symmetric horizontal bumps induce a tune shift and beta beat. By combining two of these symmetric bumps with opposite signs, where the second pair is 90deg away, the tune shift cancels and the beta beat doubles. In the low energy ring (LER), there are four -I sextupole pairs per arc, located one after another 90deg apart, where pairs 1 and 3 are at the same phase and pairs 2 and 4 are 90deg away. By making two symmetric bumps with opposite sign in pairs 1 and 3, the tune shift and beta beat outside this region cancel, but there is a local change of phase and beta in the 2n sextupole pair located in the middle. By using this bump knob, the LER lifetime improved by a factor of 3, losses by a factor of 5, and the beam-beam background in the drift chamber of the BaBar detector by 20%. Optics analysis showed that the local phase change at the 2nd sextupole pair can compensate the 3rd order chromaticity.

Published
2007
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48. A transverse beam instability in the PEP-II HER induced by discharges in the vacuum system

Author

F.-J. Decker, John Fox, S. DeBarger, Douglas Wright, W. Colocho, U. Wienands, A. Fisher, A. Kulikov, W. Wittmer, S. Ecklund, Alexander Novokhatski, M. Stanek, Gerald Yocky, and M. Sullivan

Subjects
Physics, Nuclear physics, Bellows, law, Shields, Particle accelerator, Mechanics, Current (fluid), Tracking (particle physics), Instability, Beam (structure), Background radiation, law.invention
Abstract

Towards the end of Run 5, transverse instability in the High Energy Ring (HER) curtailed the maximum beam current achievable during physics running. Techniques used in tracking down this instability included fast monitoring of background radiation, temperatures and vacuum pressure. In this way, the origin of the instability was localized and inspection of the vacuum system revealed several damaged bellows shields. Replacing these units significantly reduced the incident rate but did not eliminate it fully. After the end of the run, a number of damaged rf seals were found, possibly having caused the remaining incidents of instability. In Run 6, instability has recurred. In this paper we will outline the steps taken to diagnose the issue and compare the different signatures of instabilities we have seen in PEP-II.

Published
2007
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49. Validation of PEP-II resonantly excited turn-by-turn BMP Data

Author

F.-J. Decker, Y.T. Yan, W. Colocho, and Yunhai Cai

Subjects
Physics, Noise (signal processing), business.industry, Process (computing), Data validation, Particle accelerator, law.invention, Optics, Position (vector), law, Singular value decomposition, Turn-by-turn navigation, Invariant (mathematics), business
Abstract

For optics measurement and modeling of the PEP-II electron (HER) and position (LER) storage rings, we have been doing well with MIA which requires analyzing turn-by-turn Beam Position Monitor (BPM) data that are resonantly excited at the horizontal, vertical, and longitudinal tunes. However, in anticipation that certain BPM buttons and even pins in the PEP-II IR region would be missing for the run starting in January 2007, we had been developing a data validation process to reduce the effect due to the reduced BPM data accuracy on PEP-II optics measurement and modeling. Besides the routine process for ranking BPM noise level through data correlation among BPMs with a singular-value decomposition (SVD), we could also check BPM data symplecticity by comparing the invariant ratios. Results from PEP-II measurement will be presented.

Published
2007
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50. Correlation of beam parameters to decelerating gradient in the E-167 plasma wakefield acceleration experiment

Author

Tom Katsouleas, K. A. Marsh, M. Berry, Warren Mori, Patric Muggli, Robert H. Siemann, Dieter Walz, C. E. Clayton, Chengkun Huang, Neil Kirby, Wei Lu, C. Joshi, Rasmus Ischebeck, Mark Hogan, I. Blumenfeld, R. H. Iverson, F.-J. Decker, Erdem Oz, and Meng Zhou

Subjects
Physics, law, Cathode ray, Physics::Accelerator Physics, Metre, Particle accelerator, Plasma, Electron, Atomic physics, Plasma acceleration, Transformer, law.invention
Abstract

Recent experiments at SLAC have shown that high gradient acceleration of electrons is achievable in meter scale plasmas [1,2]. Results from these experiments show that the wakefield is sensitive to parameters in the electron beam which drives it. In the experiment the bunch length and beam waist location were varied systematically at constant charge. Here we investigate the correlation of peak beam current to the decelerating gradient. Limits on the transformer ratio will also be discussed. The results are compared to simulation.

Published
2007
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