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S. Araki,
H. Hayano,
Y. Higashi,
Y. Honda,
K. Kanazawa,
K. Kubo,
T. Kume,
M. Kuriki,
S. Kuroda,
M. Masuzawa, [......],
A. Seryi,
C. Spencer,
P. Tenenbaum,
M. Woodley,
S. Boogert,
A. Liapine,
S. Malton,
E. Torrence,
T. Sanuki,
T. Suehara
[show abstract]
[hide abstract]
ABSTRACT: To reach design luminosity, the International Linear Collider (ILC) must be able to create and reliably maintain nanometer size beams. The ATF damping ring is the unique facility where ILC emittances are possible. In this paper we present and evaluate the proposal to create a final focus facility at the ATF which, using compact final focus optics and an ILC-like bunch train, would be capable of achieving 37 nm beam size. Such a facility would enable the development of beam diagnostics and tuning methods, as well as the training of young accelerator physicists.
Particle Accelerator Conference, 2005. PAC 2005. Proceedings of the; 06/2005
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T. Higo,
M. Akemoto,
A. Enomoto,
S. Fukuda,
H. Hayano,
N. Kudo,
S. Matsumoto,
T. Saeki,
N. Terunuma, N. Toge,
K. Watanabe,
T. Suehara
[show abstract]
[hide abstract]
ABSTRACT: This paper describes the high-field studies on accelerator structures conducted at the X-band Test Facility, XTF, which was commissioned at KEK in 2004. A 60cm-long structure built at KEK has been processed in 2004-2005, with an accumulated operation time with the RF turned on of ∼ 1000 hours. The RF breakdown rate of this structure at 65MV/m with 400nsec flat pulses was initially measured to be ∼ once per 0.2×10<sup>6</sup>pulses, and decreased to ∼ once per 0.7×10<sup>6</sup>pulses with the processing. This latter breakdown rate satisfies the stability requirement for use of such accelerator structures at the linear collider. The high-power performance of two more 60cm structures will be measured in 2005. These studies are expected to provide benchmark performance data of accelerator structures in both high-gradient and medium-gradient operations, such as those envisaged in applications to compact X-band accelerators.
Particle Accelerator Conference, 2005. PAC 2005. Proceedings of the; 06/2005
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S. Dobert,
C. Adolphsen,
G. Bowden,
D. Burke,
J. Chan,
V. Dolgashev,
J. Frisch,
K. Jobe,
R. Jones,
J. Lewandowski, [......],
Y. Higashi,
T. Higo,
H. Kawamata,
T. Kume,
Y. Morozumi,
K. Takata,
T. Takatomi, N. Toge,
K. Ueno,
Y. Watanabe
[show abstract]
[hide abstract]
ABSTRACT: During the past five years, there has been an concerted program at SLAC and KEK to develop accelerator structures that meet the high gradient (65 MV/m) performance requirements for the Next Linear Collider (NLC) and Global Linear Collider (GLC) initiatives. The design that resulted is a 60-cm-long, traveling-wave structure with low group velocity and 150 degree per cell phase advance. It has an average iris size that produces an acceptable short-range wakefield, and dipole mode damping and detuning that adequately suppresses the long-range wakefield. More than eight such structures have operated at a 60 Hz repetition rate over 1000 hours at 65 MV/m with 400 ns long pulses, and have reached breakdown rate levels below the limit for the linear collider. Moreover, the structures are robust in that the rates continue to decrease over time, and if the structures are briefly exposed to air, the rates recover to their low levels within a few days. This paper presents a summary of the results from this program, which effectively ended last August with the selection of ‘cold’ technology for an International Linear Collider (ILC).
Particle Accelerator Conference, 2005. PAC 2005. Proceedings of the; 06/2005
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Y Honda,
K Kubo,
S Anderson,
S Araki,
K Bane,
A Brachmann,
J Frisch,
M Fukuda,
K Hasegawa,
H Hayano, [......], N Toge,
J Urakawa,
V Vogel,
M Woodley,
A Wolski,
I Yamazaki,
Yoshio Yamazaki,
G Yocky,
A Young,
F Zimmermann
[show abstract]
[hide abstract]
ABSTRACT: For high luminosity in electron-positron linear colliders, it is essential to generate low vertical emittance beams. We report on the smallest vertical emittance achieved in single-bunch-mode operation of the Accelerator Test Facility, which satisfies the requirement of the x-band linear collider. The emittances were measured with a laser-wire beam-profile monitor installed in the damping ring. The bunch length and the momentum spread of the beam were also recorded under the same conditions. The smallest vertical rms emittance measured at low intensity is 4 pm at a beam energy of 1.3 GeV, which corresponds to the normalized emittance of 1.0x1.0(-8) m. It increases by a factor of 1.5 for a bunch intensity of 10(10) electrons. The measured data agreed to the calculation of intrabeam scattering within much better than a factor of 2.
Physical Review Letters 03/2004; 92(5):054802. · 7.37 Impact Factor
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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
[show abstract]
[hide abstract]
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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[show abstract]
[hide abstract]
ABSTRACT: Vacuum breakdown characteristics of oxygen-free copper electrodes processed by precision machining were investigated by applying impulse voltage As a result, processed electrodes by precision machining showed higher conditioning effect than those of electrodes without the process. And the conditioning was achieved with less number of breakdowns. Accordingly the precision machining and the subsequent hydrogen annealing are effective in improving breakdown fields of the early stage of conditioning process.
Discharges and Electrical Insulation in Vacuum, 2002. 20th International Symposium on; 02/2002
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Y.H. Chin,
S. Matsumoto,
H. Mizuno,
Y. Morozumi,
T. Ohkawa,
K. Ohya,
K. Takata, N. Toge,
S. Tokumoto,
S. Kazakov,
A. Larionov,
V. Teryaev
[show abstract]
[hide abstract]
ABSTRACT: In this paper, we summarize the status of X-band PPM klystron
development for the Japan Linear Collider (JLC) project. The periodic
permanent magnet (PPM) klystrons are under development in the
two-stage/two-year project with Toshiba. The goal is to produce 50 MW
output power with efficiency >50% at 1.5 μs pulse length at the
first klystron and then to advance to 75 MW with efficiency =55% at the
second one. The first PPM klystron has been tested, and it achieved 56
MW power with 50% efficiency at the standard 1.5 μs pulse length.
Neither oscillation of the parasitic mode nor gun oscillations were
observed. The particle transmission was found to be 100% when no RF
signal is applied. The second PPM klystron is currently under high-power
testing. It has improved water cooling system of a PPM circuit and the
output cavity for 150 Hz operation. The RF system was also revised for a
higher efficiency. To date (June 6, 2001), the PPM-2 klystron produced
73.2 MW at 1.4 μs pulse length and 70 MW at 1.5 μs pulse length
with the efficiency of 54.5%. The maximum efficiency reached 56% at the
specified cathode voltage. The high-power testing will be continued to
attain a 75 MW output power with a standard 1.5 μs pulse. Details of
these developments and measurement results are presented
Particle Accelerator Conference, 2001. PAC 2001. Proceedings of the 2001; 02/2001
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J W Wang,
C. Adolphsen,
G. B. Bowden,
D. L. Burke,
J. Cornuelle,
V. A. Dolgashev,
W. B. Fowkes,
R.K. Jobe,
R. M. Jones,
K Ko, [......],
G. Stupakov,
T. Higo,
Y. Funahashi,
Y Higashi,
N. Hitomi,
T Suzuki,
K Takata,
T. Takatomi, N. Toge,
Y Watanabe
[show abstract]
[hide abstract]
ABSTRACT: As a joint effort in the JLC/NLC research program, we have developed a new type of damped detuned accelerator structure with optimized round-shaped cavities (RDDS). This paper discusses some important R&D aspects of the first structure in this series (RDDS1). The design aspects covered are the cell design with sub-MHz precision, HOM detuning, coupling and damping technique and wakefield simulation. The fabrication issues covered are ultra-precision cell machining with micron accuracy, assembly and diffusion bonding technologies to satisfactorily meet bookshelf, straightness and cell rotational alignment requirements. The measurements described are the RF properties of single cavities and complete accelerator section, as well as wakefields from the ASSET tests at SLAC. Finally, future improvements are also discussed.
10/2000;
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[show abstract]
[hide abstract]
ABSTRACT: In fabricating the first X-Band RDDS (Rounded Damped Detuned Structure) accelerator structure, microwave measurements are made on short groups of discs prior to bonding the discs of the entire structure. The design dispersion curves are compared with the frequency measurements. The theory utilised is based on a circuit model adapted to a short stack of slowly varying non-uniform discs. The model reveals the nature of the modes in the structure and may also be used to refit the experimental data to the parameters in a model of the wakefield given earlier [1]. This method allows a more faithful determination of the wakefield that a beam will experience as it traverses the structure. Results obtained on the frequencies are compared to the original design. [1] R.M.Jones, et al, EPAC96 (also SLAC-PUB-7187)
09/2000;
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T. Higo,
Y. Funahashi,
Y Higashi,
N. Hitomi,
T Suzuki,
K Takata,
T. Takatomi, N. Toge,
Y Watanabe,
Z Li,
R. H. Miller,
J W Wang
[show abstract]
[hide abstract]
ABSTRACT: Following successful design and fabrication of damped detuned structures, the R&D for the accelerating structures of the NLC/JLC linear collider project proceeded to studies of Rounded Damped Detuned Structure with curved cross section of the cavity shape for increased shunt impedance. The important features of the structure are the accurately tuned accelerating mode frequency and the distribution of the first dipole modes smooth and close to the design distribution. These requirements were met based on the high-accuracy diamond turning with its capability to realize the periphery tolerance of two microns. The lowest dipole mode frequencies scattered by 0.6 MHz RMS. The error in the accelerating mode frequency averaged over a structure was 0.1 MHz by applying a feed-forward method.
09/2000;
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[show abstract]
[hide abstract]
ABSTRACT: A superconducting final focus magnet system for the interaction
region of KEKB was constructed. It consists of two solenoid field
compensation magnets and two superconducting quadrupoles with three
kinds of correction coils. The system test has been successfully
completed. This paper describes the design, construction and the test
results of these magnets
IEEE Transactions on Appiled Superconductivity 07/1999; · 1.04 Impact Factor
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J. Klingmann,
J. Elmer,
M. Mugge,
K. van Bibber,
K. Asano,
Y. Funahashi,
Y. Higashi,
T. Higo,
N. Hitomi,
T. Suzuki, [......],
C. Adolphsen,
H. Hoag,
R. Jones,
N. Kroll,
R. Miller,
C. Pearson,
R. Pope,
J. Rifkin,
R. Ruth,
J. Wang
[show abstract]
[hide abstract]
ABSTRACT: A 1.8 m X-band damped-detuned structure (DDS-3) has been
fabricated and characterized as part of the structure development
program towards a TeV-scale e<sup>+</sup>e<sup>-</sup> linear collider.
In this joint venture, the Cu cells were precision-fabricated by LLNL,
diffusion-bonded into a monolithic structure by KEK, and the structure
completed and tested by SLAC. The overall process constitutes a baseline
for future high-volume structure manufacture
Particle Accelerator Conference, 1999. Proceedings of the 1999; 02/1999
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Y.H. Chin,
M. Akemoto,
S. Fukuda,
S. Matsumoto,
S. Michizono,
H. Mizuno,
K. Takata, N. Toge,
S. Tokumoto,
H. Tsutsui,
S. Yamaguchi,
J. Wang,
S. Kazakov
[show abstract]
[hide abstract]
ABSTRACT: In this paper, we summarize our activities on X-band RF power
source development for the Japan Linear Collider (JLC) project. First,
we have designed and tested a solenoid-focused klystron at 11.424 GHz
with a pulse length of 1.5 μs and with an efficiency of 47%. A
periodic permanent magnet (PPM) klystron, the first in that kind at KEK,
is also under development. In parallel to this activity, another PPM
klystron has been developed and remodeled in collaboration with BINP.
Second, a new RF window with 100-MW power-handling capability has been
designed and tested. It utilizes the TW mixed mode (TE11 and TM11 modes)
to reduce the surface field at the brazing edge of the ceramic. The cold
model test shows a low electric field at the brazing point as predicted
by HFSS calculations. The high power model is now in manufacturing and
the testing will start soon. Third, the Blumlein modulator was upgraded
to produce a pulse with 2 μs flat top and 200 ns rise time at 550 kV
output voltage. Fourth, the multi-mode 2×2 DLDS (Delay Line
Distribution System) pulse compression system has been designed, and its
basic unit was manufactured and tested for proof of the principle. The
measurement results show that the system works well with a high power
distribution efficiency. The so-called mode stability experiment is also
under preparation in the ATF linac tunnel in collaboration with SLAC.
This experiment is aimed for examination of the stability of linearly
polarized TE12 mode in a 55 m long waveguide, a key issue in the present
configuration of multi-mode DLDS. Details of these developments and
measurement results are presented
Particle Accelerator Conference, 1999. Proceedings of the 1999; 02/1999
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J.W. Wang,
C. Adolphsen,
K.L. Bane,
G.B. Bowden,
D.L. Burke,
H. Deruyter,
J. Cornuelle,
Z.D. Farkas,
W.B. Fowkes,
S. Hanna, [......],
N. Hitomi,
T. Suzuki,
K. Takata,
T. Takatomi, N. Toge,
Y. Watanabe,
J. Elmer,
J. Klingmann,
M. Mugge,
K. Van Bibber
[show abstract]
[hide abstract]
ABSTRACT: For more than ten years, we have been working on R&D for
X-band accelerator structures for the JLC/NLC linear collider. Several
types of Detuned (DS) and Damped Detuned Structures (DDS) have been
successfully designed and fabricated. They have been experimentally
tested at both low power and high power to characterize their mechanical
and electrical properties. Recently we started developing a new type of
damped detuned structure with optimized round-shaped cavities (RDDS).
This paper discusses the special specifications, design methods,
fabrication procedures, measurement technologies, and anticipated future
improvements for all these structures
Particle Accelerator Conference, 1999. Proceedings of the 1999; 02/1999
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[show abstract]
[hide abstract]
ABSTRACT: In order to achieve an extremely low emittance down to
ε<sub>y</sub>~1×10<sup>-11</sup> m-rad, the beam development
has been continued at KEK-ATF for future linear collider. The emittance
measurement in the damping ring is a key point to confirm the low
emittance beam. The beam size measurement is done by SR interferometer
using visible light (~500 nm) at ATF damping ring. The measured beam
sizes were already reached less than 14 μm (vertical) acid 37 μm
(horizontal), respectively. The beta function was also measured by
applying a perturbation on the quadrupole magnet. The dispersion
function was measured by means of RF frequency modulation method.
Combining these measured values, the emittance was measured as ε
<sub>x</sub>=1.8×10<sup>-9</sup> m-rad,
ε<sub>y</sub>=6.1×10<sup>-11</sup> m-rad. The measurement
technologies are described
Particle Accelerator Conference, 1999. Proceedings of the 1999; 02/1999
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H. Hayano,
S. Kamada,
K. Kubo,
T. Naito,
K. Oide,
N. Terunuma, N. Toge,
J. Urakawa,
S. Kashiwagi,
T. Okugi,
M. Takano,
K. Bane,
T. Kotseroglou,
M. Minty,
M. Ross,
J. Turner,
M. Woodley,
F. Zimmermann
[show abstract]
[hide abstract]
ABSTRACT: The target of KEK-ATF is producing electron beam with vertical
emittance of 0.01 nm-rad (1×10<sup>-11</sup> m-rad). Corrections
of the dispersions are essential to achieve the low emittance. Because
the actual optics of the beam line should be known for these
corrections, beam based optics diagnostics has been performed.
Simulations showed the validity and the accuracy of the method. Effects
of skew quadrupoles have also been studied
Particle Accelerator Conference, 1999. Proceedings of the 1999; 02/1999
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K. Abe,
V. Ashford,
D. Aston,
T. Bienz,
K. Baird,
F. Bird,
M. Cavalli-Sforza,
J. Coller,
P. Coyle,
D. Coyne, [......], N. Toge,
J. Va'vra,
T. Weber,
J.S. Whitaker,
R.J. Wilson,
D. Williams,
S.H. Williams,
S. Willocq,
S. Yellin,
H. Yuta
[show abstract]
[hide abstract]
ABSTRACT: The Barrel CRID detector has been operating successfully at SLD
for the past seven years. It is an important tool for SLD physics
analyses. We report results based on long term operational experience of
a number of important quantities such as the Cherenkov quality factor, N
<sub>0</sub> of the device, fluid transparency, electron lifetime,
single electron detection efficiency, anode wire ageing, TMAE purity,
long term transparency, Cherenkov angle resolution and the number of
photoelectrons observed per ring
IEEE Transactions on Nuclear Science 07/1998; · 1.45 Impact Factor
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K. Abe,
P. Antilogus,
D. Aston,
K. Baird,
C. Baltay,
A. Bean,
R. Ben-David,
T. Bienz,
F. Bird,
D.O. Caldwell, [......],
J. Va'vra,
T. Weber,
J.S. Whitaker,
D.A. Williams,
S.H. Williams,
S. Willocq,
R.J. Wilson,
G. Word,
S. Yellin,
H. Yuta
[show abstract]
[hide abstract]
ABSTRACT: We present the Cherenkov ring imaging detector in the endcap
regions of the SLD detector and report initial performance. The endcap
CRID was completed and commissioned in 1993 and is fully operational for
the 1994 run. First Cherenkov rings have been observed. The endcap CRID
detectors and fluid systems are described and initial operational
experience is discussed
IEEE Transactions on Nuclear Science 09/1995; · 1.45 Impact Factor
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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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K. Abe,
P. Antilogus,
D. Aston,
K. Baird,
A. Bean,
R. Ben-David,
T. Bienz,
F. Bird,
D.O. Caldwell,
M. Cavalli-Sforza, [......],
J. Turk,
J. Va'vra,
J.S. Whitaker,
D.A. Williams,
S.H. Williams,
S. Willocq,
R.J. Wilson,
G. Word,
S. Yellin,
H. Yuta
[show abstract]
[hide abstract]
ABSTRACT: We report on operational experience with and experimental
performance of the SLD barrel Cherenkov Ring Imaging Detector from the
1992 and 1993 physics runs. The liquid (C<sub>6</sub>F<sub>14</sub>) and
gas (C<sub>5</sub>F<sub>12</sub>) radiator recirculation systems have
performed well, and the drift gas supply system has operated
successfully with TMAE for three years. Cherenkov rings have been
observed from both the liquid and gas radiators. The number and angular
resolution of Cherenkov photons have been measured, and found to be
close to design specifications
IEEE Transactions on Nuclear Science 09/1994; · 1.45 Impact Factor
