Paper | Title | Page |
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MOPLH06 | Study of the Mean Transverse Energy and the Emission Mechanism of (N)UNCD Photocathodes | 181 |
SUPLE12 | use link to see paper's listing under its alternate paper code | |
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Funding: This project is supported by NSF grant No. NSF-1739150, NSF-1535676, and NSF grant No. PHYS-1535279. Nitrogen incorporated ultrananocrystalline diamond ((N)UNCD) is promising for photocathode applications due to its high quantum efficiency (QE). The mean transverse energy (MTE) which, along with QE, defines the brightness of the emitted electron beam must be thoroughly characterized and understood for (N)UNCD. Our previous work* further corroborated the important role of graphitic grain boundaries (GB’s). UNCD consists of diamond (sp3-hybrized) grains and graphitic (sp2-hybrized) GB’s: GB’s are behind the high emissivity of (N)UNCD and therefore play a crucial role in defining and controlling the MTE. In this work, the MTE of two different (N)UNCD samples having different ratios of sp3/sp2 were measured versus the primary photon energies. As a reference, MTE of highly oriented pyrolytic graphite (HOPG, canonical sp2-hybrized graphite) was also measured. * G. Chen et al., Appl. Phys. Lett. 114, 093103 (2019). |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-MOPLH06 | |
About • | paper received ※ 27 August 2019 paper accepted ※ 12 September 2019 issue date ※ 08 October 2019 | |
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TUPLO01 | Dual-Function Electron Ring-Ion Booster Design for JLEIC High-Energy Option | 529 |
SUPLH10 | use link to see paper's listing under its alternate paper code | |
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Funding: This work was supported by the U.S. DOE, Office of Nuclear Physics, under Contract No. DE-AC02-06CH11357 for ANL and by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. As part of the alternative design approach for the Jeffer-son Laboratory Electron-Ion Collider (JLEIC) ion com-plex, the electron storage ring (e-ring) is consolidated to also serve as a large booster for the ions. The goal of reaching 16 GeV/u or higher for all ions using only room-temperature magnets forces the re-design of the e-ring because of magnetic field and lattice limitations. The new design is challenging due to several imposed constraints: (1) use of room-temperature magnets, (2) avoiding transi-tion crossing, and (3) maintaining the size and shape of the original e-ring design as much as possible. A design study is presented for a 16 GeV/u large ion booster after analyzing different alternatives that use: (1) combined-function magnets, (2) large quadrupoles or (3) quadrupole doublets in the lattice design. This design boosts the injection energy to the collider ring from 8 GeV (proton-equivalent) in the original baseline design to 16 GeV/u for all ions which is beneficial for the high-energy option of JLEIC of 200 GeV or higher. A scheme for adapting the new large ion booster design to also serve as electron storage ring is presented. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUPLO01 | |
About • | paper received ※ 28 August 2019 paper accepted ※ 05 September 2019 issue date ※ 08 October 2019 | |
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TUPLO02 | Spin Dynamics in the JLEIC Ion Injector Linac | 533 |
SUPLH11 | use link to see paper's listing under its alternate paper code | |
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Funding: This work was supported by the U.S. DOE, Office of Nuclear Physics, under Contract No. DE-AC02-06CH11357 for ANL and by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. One of the requirements for the future Electron Ion Col-lider (EIC) is to collide polarized electrons and light ions with at least 70% polarization for each beam. For light ions, polarized ion sources are used for injection to a linac, which is usually the first accelerator in the collider chain. The Jefferson Lab EIC (JLEIC) ion injector linac consists of a low-energy room-temperature section with quadrupole focusing followed by a superconducting linac with solenoid focusing inside long cryomodules. These two sections have different effects on the spin. Spin dy-namics simulation studies are carried out for the JLEIC injector linac in order to preserve and maintain a high degree of polarization for light ion beams for delivery to the booster. The different options to maintain and restore the spin in the different sections of the linac for hydrogen, deuterium and helium ions are presented and discussed. Results from both the Zgoubi and COSY-Infinity codes are presented and compared for every section of the ion linac but the radio-frequency quadrupole (RFQ). Current-ly, a method to simulate the RFQ using Zgoubi is being investigated. |
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DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUPLO02 | |
About • | paper received ※ 28 August 2019 paper accepted ※ 19 November 2019 issue date ※ 08 October 2019 | |
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TUPLE16 | RFA Measurement of E-Cloud Generation Process at Fermilab Main Injector | 595 |
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Fermilab aims to provide greater beam power for the neutrino physics program. As the beam power increases, the unwanted production of secondary electrons in the beam pipe, known as ‘electron cloud’ or ‘E-cloud’ may become disruptive to high intensity operation. Instrumentation has been deployed in the Fermilab Main Injector (MI) to study E-cloud. One of these is a Retard Field Analyzer (RFA) that can be used to directly measure E-cloud generation at the location of the instrument. Studies of the dependence of E-cloud on beam intensity and bunch length have been carried out. The experimental results are compared to POSINST simulations. These simulations are guided by measurements from a Secondary Electron Yield (SEY) test stand installed in the MI to measure the SEY of materials such as the beam pipe stainless steel. The SEY has a strong influence on the E-cloud density. Results of these comprehensive studies comparing the RFA data with realistic MI simulations will be presented. | ||
DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUPLE16 | |
About • | paper received ※ 28 August 2019 paper accepted ※ 06 September 2019 issue date ※ 08 October 2019 | |
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