CEBAF commissioning and future plans

Grunder, Hermann A.

doi:10.1109/pac.1995.504555

Cited by 12 publications

(4 citation statements)

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“…CEBAF [36] is a superconducting, recirculating electron-beam accelerator utilizing two linear accelerators (linacs) and two bending sections. With energies between 800 MeV and 6 GeV, it can probe the nuclear medium in a transition region where the conventional interaction description changes from baryon-meson exchange to quarkgluon interactions.…”

Section: The Cebaf Acceleratormentioning

confidence: 99%

“…Each cavity had an independently regulated 5 W klystron such that it could be individually tuned for optimal performance [39]. The decision to use the relatively young superconducting cavity technology was made in an attempt to limit the power consumption of the machine [36] by substantially reducing the amount of energy lost as heat and to cooling efforts.…”

Section: The Cebaf Acceleratormentioning

confidence: 99%

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Measurement of the Unpolarized K+ Λ and K+ Σ0 Electroproduction Cross Sections and Interference Terms from the Proton with the CLAS Detector

Feuerbach¹

2002

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Using the CLAS detector, we measure the K + Λ and K + Σ 0 electroproduction response functions over the continuous kinematic range from threshold to W = 2.05 GeV and for Q 2 between 0.5 and 1.5 (GeV/c) 2 , with nearly complete angular coverage in the center-of-momentum frame angles. The σ T + σ L , σ T T and σ LT terms are extracted and compared to recent theoretical calculations based upon a hadrodynamic effective-Lagrangian framework. From examining the W-dependence of the response functions for the K + Λ final state, we find features in the (σ T + σ L) term in the W = 1.75 to 1.90 GeV region, similar to features seen in recent photoproduction results. In general, the σ T T and σ LT response-functions for Λ production are of the same order of magnitude as the (σ T + σ L) term, suggesting that both σ T and σ L contribute significantly. For the K + Σ 0 final state the W-dependence of the (σ T + σ L) and σ T T terms have large, resonant-like features near W = 1.9 GeV. Unlike in Λ electroproduction, the σ LT interference term for Σ 0 electroproduction is found to be consistent with zero across nearly the entire kinematic range, while σ T T is comparable in magnitude to the σ T + σ L differential cross-section. The models, while achieving some qualitative agreement with the data, fail to both describe the details of the angular distributions and reproduce the resonant-like behavior observed. i Acknowledgments This measurement was the result of the contributions and hard work of many individuals, to whom I am thankful. I would like to specifically acknowledge the assistance and support offered by the Jefferson Lab staff, the past and present members of the CLAS Collaboration, and by all the members of the CMU Medium Energy group. My financial support was provided by the Department of Energy. Finally, I owe the completion of this project to the emotional support of friends and family. I would like to thank the Medium Energy Group at CMU for their assistance, support and for maintaining an open and (relatively) stress-free environment in which to work. First, I am grateful to my advisor, Reinhard Schumacher, for his support, council, and shared experience throughout the duration. My also thanks go out to my longtime friend, colleague, and office-mate John McNabb for the relentless discussions and debates, occasional distractions, and overall support. I am indebted to Bob Bradford for his friendship and selfless assistance. Paul Eugenio and Kent Paschke both possessed an inspirational enthusiasm, on the softball field and in the office, that made my graduate-student life and work more enjoyable. My discussions with Professors Curtis Meyer, Gregg Franklin, and Brian Quinn helped broaden my view of nuclear physics beyond my specific experiment, as well as improving the analysis, and are valued as well. I would like to also thank Professors Robert Kraemer and Frank Tabakin for serving on my thesis committee. I wish to thank Si McAleer and Steve Barrow for their tireless efforts to process the data used in this analysis, as...

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Section: The Cebaf Acceleratormentioning

confidence: 99%

Section: The Cebaf Acceleratormentioning

confidence: 99%

Measurement of the Unpolarized K+ Λ and K+ Σ0 Electroproduction Cross Sections and Interference Terms from the Proton with the CLAS Detector

Feuerbach¹

2002

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“…The Continuous Electron Beam Accelerator Facility (CEBAF) at Jefferson Lab has forty 8-cavity cryomodules (CMs) originally built in the 1990s [1]. Field emission is the main limitation for the operation of the cryomodules and results in a steady beam energy loss over time [2].…”

Section: Introductionmentioning

confidence: 99%

Cavity Production and Testing of the First C75 Cryomodule for CEBAF

Ciovati

Cheng

Daly

et al. 2022

International Conference on RF Superconductivity (20th), East Lansing, MI, USA, 28 June-02 July 2021

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The CEBAF cryomodule rework program was updated over the last few years to increase the energy gain of refurbished cryomodules to 75 MeV. The concept recycles the waveguide end-groups from original CEBAF cavities fabricated in the 1990s and replaces the five elliptical cells in each with a new optimized cell shape fabricated from large-grain, ingot Nb material. Eight cavities were fabricated at Research Instruments, Germany, and two cavities were built at Jefferson Lab. Each cavity was processed by electropolishing and tested at 2.07 K. The best eight cavities were assembled into "cavity pairs" and re-tested at 2.07 K, before assembly into the cryomodule. All but one cavity in the cryomodule were within 10% of the target accelerating gradient of 19 MV/m with a quality factor of 8×10 9 . The performance limitations were field emission and multipacting.

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“…The superconducting RF (SRF) accelerator at Jefferson Lab, CEBAF, was originally completed in 1994 [1]. It is 1.4 km in circumference and has a race-track shape, of the recirculated linear accelerator type.…”

Section: Introductionmentioning

confidence: 99%

Pursuing the Origin and Remediation of Low Q0 observed in the Original CEBAF Cryomodules

Fischer

et al. 2014

IPAC2014 - Proceedings, Dresden, Germany, June 16-20, 2014

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We report on results of a new investigation into the Q 0 degradation phenomenon observed in original CEBAF cavities when assembled into cryomodules. As a result, the RF dissipation losses increased by roughly a factor of two. The origin of the degradation, first observed in 1993, has remained unresolved up to current period, despite much effort. Recently, a new investigation has been launched, in parallel with cryomodule refurbishment. Systematic measurements are conducted with respect to the magnetic shielding effects of the double-layer shields and the magnetic properties of various components within the inner shield. This resulted in the new discovery of strongly magnetized strut springs as a major source of remanent magnetic flux near a cavity inside of all magnetic shielding. New springs with superior magnetic properties have been found, evaluated and implemented. Preservation of Q 0 from vertical testing to cryomodule testing in tunnel at 5 MV/m gradient in the range of 79-88% has been measured. Studies for complete Q 0 preservation and possible Q 0 remediation for those 330 cavities already installed in CEBAF are carried out and preliminary results are also presented.

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CEBAF commissioning and future plans

Cited by 12 publications

References 0 publications

Measurement of the Unpolarized K<sup>+</sup> Λ and K<sup>+</sup> Σ<sup>0</sup> Electroproduction Cross Sections and Interference Terms from the Proton with the CLAS Detector

Measurement of the Unpolarized K<sup>+</sup> Λ and K<sup>+</sup> Σ<sup>0</sup> Electroproduction Cross Sections and Interference Terms from the Proton with the CLAS Detector

Cavity Production and Testing of the First C75 Cryomodule for CEBAF

Pursuing the Origin and Remediation of Low Q0 observed in the Original CEBAF Cryomodules

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