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ABSTRACT: At the Interaction Point (IP) of the SLC Final Focus, beam-beam deflection scans routinely provide a measurement of the sum in quadrature of the electron and positron transverse beam sizes, but no information on the individual beam sizes. During the 1996 SLC run, an upgrade to the Final Focus beam position monitor system allowed a first measurement of the absolute beam energy loss of both beams on each step of the deflection scan. A fit to the energy loss distributions of the two beams provides a measurement not only of the individual transverse beam sizes at the IP but also of the individual bunch lengths.
08/2011
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K Kubo,
M Akemoto,
S Anderson,
T Aoki,
S Araki,
K L F Bane,
P Blum,
J Corlett,
K Dobashi,
P Emma, [......],
Seishi Takeda,
N Terunuma,
N Toge,
J Turner,
J Urakawa,
V Vogel,
M Woodley,
J Yocky,
A Young,
F Zimmermann
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ABSTRACT: Electron beams with the lowest, normalized transverse emittance recorded so far were produced and confirmed in single-bunch-mode operation of the Accelerator Test Facility at KEK. We established a tuning method of the damping ring which achieves a small vertical dispersion and small x-y orbit coupling. The vertical emittance was less than 1% of the horizontal emittance. At the zero-intensity limit, the vertical normalized emittance was less than 2.8 x 10(-8) rad m at beam energy 1.3 GeV. At high intensity, strong effects of intrabeam scattering were observed, which had been expected in view of the extremely high particle density due to the small transverse emittance.
Physical Review Letters 06/2002; 88(19):194801. · 7.37 Impact Factor
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ABSTRACT: We report the first high-gradient studies of a millimeter-wave accelerator, employing for the first time a planar dielectric accelerator, powered by means of a 0.5-A, 300-MeV, 11.424-GHz drive electron beam, synchronous at the 8th harmonic, 91.392 GHz. Embedded in a ring-resonator circuit within the electron beam line vacuum, this structure was operated at 20 MeV/m, with a circulating power of 200 kW, for 2 x 10(5) pulses, with no sign of breakdown, dielectric charging, or other deleterious high-gradient phenomena. We also present the first measurement of the quadrupolar content of an accelerating mode.
Physical Review Letters 09/2001; 87(9):094801. · 7.37 Impact Factor
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ABSTRACT: We present wakefield measurements of a prototype Next Linear
Collider (NLC) accelerator structure that was built with dipole mode
damping and detuning to suppress the long-range transverse wakefield
induced by a beam. In addition, we describe beam centering tests that
use as a guide the dipole power coupled out of the structure for damping
purposes
Particle Accelerator Conference, 1999. Proceedings of the 1999; 02/1999
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ABSTRACT: INTRODUCTION The SLC feedback system [1,2] is a generalized, database driven system that applies state-space formalisms to stabilize the beam. Feedback has proven to be essential to the successful operation of the SLC. Problems encountered in running high current beams have forced us to adopt tighter tolerances on feedback control parameters and have motivated a stricter evaluation of feedback performance. Of particular concern is the fact that linac feedback loops are routinely operated with lower than design gain. The design of each feedback loop relies on knowledge of the slew rates of the correctors used to cancel perturbations and of the noise spectrum of the beam. The effect of differences in corrector speeds has been measured and analyzed using high current beams. For a series of loops in succession correction for over compensation, or cascade [3], was found to be necessary, in which information from each loop is passed on to the loop immediately downstream. The transf
04/1998;
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C. Adolphsen,
R Assmann,
F.-J. Decker,
P. Emma,
J Frisch,
L. J. Hendrickson,
P. Krejcik,
M. Minty,
N Phinney,
P. Raimondi,
M.C. Ross, T Slaton,
W. Spence,
R. Stege,
H Tang,
F Tian,
J Turner
[show abstract]
[hide abstract]
ABSTRACT: Although the SLC achieved record luminosity in 1994, a major hindrance to further increases is pulse-to-pulse stability of the machine, often referred to as jitter. Raising the intensity of the SLC beams has gained luminosity but the intensity-normalized luminosity has decreased due to additional emittance dilution and to increasing jitter at higher intensities. Precision tuning of the final focus using beam-beam deflection scans is hampered by the pulse-topulse variations in both beam position and beam size. These were traced to position, intensity and energy jitter in various subsystems of the collider. Contributions to both the origin and amplification of the jitter have been identified as coming from wakefields in the linac, instabilities in the damping rings, acceptance limitations and feedback performance. The intensity fluctuations from the source can easily be amplified as a result of the SLC configuration of accelerating the two electron and positron bunches in the same linac....
04/1998;
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F. Zimmermann,
T. Barklow,
S. Ecklund,
P. Emma,
D. McCormick,
N. Phinney,
P. Raimondi,
M. Ross, T. Slaton,
E. Tian,
J. Turner,
M. Woodley,
M. Placidi,
N. Toge,
N. Walker
[show abstract]
[hide abstract]
ABSTRACT: A major upgrade to the SLC final focus was installed in 1994 to
eliminate the dominant third-order aberration of the system, and thereby
to reduce the vertical beam size at the IP by a factor of two. At low
current, the optimal beam size of about 400 nm is now routinely
established, and its sensitivity to orbit variations, to changes of
emittance and energy spread, and to other beam parameters has been
studied. For intensities above 3×10<sup>10</sup> particles per
bunch, tuning is more difficult due to increased fluctuations of energy,
orbit, and emittances. Nonetheless, the expected beam size of about 600
nm has been observed. New procedures and diagnostics allow easier tuning
and optimization of the final focus, and also a first measurement of the
emittance increase in the arcs
Particle Accelerator Conference, 1995., Proceedings of the 1995; 06/1995
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[show abstract]
[hide abstract]
ABSTRACT: Many feedback loops are used at the Stanford Linear Collider (SLC)
to control the orbit and energy of particle beams. Problems with
corrector magnet slew rates, actuator calibrations, and computation of
the beam transport matrix between loops have resulted in operation of
many SLC feedback loops at lower than design gain. The response of
various feedback loops to these errors is measured and analyzed in an
attempt to improve performance
Particle Accelerator Conference, 1995., Proceedings of the 1995; 06/1995
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C. Adolphsen,
R. Assmann,
F.J. Decker,
P. Emma,
J. Frisch,
L.J. Hendrickson,
P. Krejcik,
M. Minty,
N. Phinney,
P. Raimondi,
M.C. Ross, T. Slaton,
W. Spence,
R. Stege,
H. Tang,
F. Tian,
J. Turner,
M. Woodley,
F. Zimmermann
[show abstract]
[hide abstract]
ABSTRACT: Although the SLC achieved record luminosity in 1994, a major
hindrance to further increases is pulse-to-pulse stability of the
machine, often referred to as jitter. Raising the intensity of the SLC
beams has gained luminosity but the intensity-normalized luminosity has
decreased due to additional emittance dilution and to increasing jitter
at higher intensities. Precision tuning of the final focus using
beam-beam deflection scans is hampered by the pulse-to-pulse variations
in both beam position and beam size. These were traced to position,
intensity and energy jitter in various subsystems of the collider.
Contributions to both the origin and amplification of the jitter have
been identified as coming from wakefields in the linac, instabilities in
the damping rings, acceptance limitations and feedback performance. The
intensity fluctuations from the source can easily be amplified as a
result of the SLC configuration of accelerating the two electron and
positron bunches in the same linac
Particle Accelerator Conference, 1995., Proceedings of the 1995; 06/1995
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[show abstract]
[hide abstract]
ABSTRACT: We present model-independent measurements of the vertical
trajectory jitter of the positron beam in the Stanford Linear Collider
(SLC) linac and discuss the results of studies aimed at isolating its
source
Particle Accelerator Conference, 1995., Proceedings of the 1995; 06/1995
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Frank Zimmermann,
Timothy L Barklow,
S D Ecklund,
P. Emma,
D. McCormick,
N Phinney,
Pantaleo Raimondi,
M Ross, T Slaton,
F Tian,
J Turner,
M. Woodley,
Massimo Placidi,
N. Toge,
N. Walker
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