IPAC2017 - List of Authors (Gulliford, C.M.)

Paper	Title	Page
MOPIK023	Cornell Laboratory for High Intensity, Ultra-Bright and Polarized Electron Beams	551
	L. Cultrera, A.C. Bartnik, I.V. Bazarov, C.M. Gulliford, P. Gupta, H. Lee, S.A. McBride, T.P. Moore Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	Funding: This work has been funded by the National Science Foundation (Grant No. PHY-1416318) and Department of Energy (Grants No. DE-SC0014338, No. DE-SC0011643 and No. DE-SC0016203). We report on the current activities pursued at Cornell University for the production of electron beams tailored to a wide range of applications. We have developed the expertise to grow many different type of high quantum efficiency photocathode belonging to the alkali antimonide family. Those materials are ideal candidates to produce high intensity beam with average currents in the mA range. When operated near threshold at cryogenic temperature in transmission mode they can also generate the electron beams needed to perform ultrafast electron diffraction of bio molecules. We have recently expanded our facility with a Mott polarimeter to include the capability to measure polarization of the electron beam. The photocathode lab is being complemented by a dedicated photo-gun laboratory to test the photocathode properties in a real environment and to perform measurement of the beam properties under new and yet unexplored operating conditions.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPIK023
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TUPAB126	Multi-objective Genetic Optimization of Single Shot Ultrafast Electron Diffraction Beamlines	1615
	C.M. Gulliford, A.C. Bartnik, I.V. Bazarov Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA J.M. Maxson UCLA, Los Angeles, California, USA
	We present the results of multi-objective genetic algorithm optimizations of two single-shot ultrafast electron diffraction (UED) beam lines. The first is based on a 225 kV dc gun featuring a novel cryocooled photocathode system and buncher cavity. The second uses a 100 MV/m 1.6 cell normal conducting rf (NCRF) gun, as well as a 9 cell 2 Pi/3 bunching cavity placed between two solenoids. Optimizations of the transverse projected emittance as a function of bunch charge are presented and discussed in terms of the scaling laws derived in the charge saturation limit. Additionally, optimization of the transverse coherence length as a function of final rms bunch length at the sample location have been performed. These results demonstrate the viability of the approaches taken for both beamlines studied as well as the use of using genetic algorithms in the design and operation of UED beamlines.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB126
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TUPAB128	Single Photoemitter Tips in a DC Gun: Limiting Aberration-induced Emittance	1622
	I.V. Bazarov, L. Cultrera, C.M. Gulliford, H. Lee Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA H.K. Fung Cornell University, Ithaca, New York, USA J.M. Maxson UCLA, Los Angeles, California, USA
	Ultrafast electron diffraction (UED) offers unique advantages over x-ray diffraction, like stronger scattering cross-section, versatility in sample types and ability to offer smaller apparatus foot print. There is a growing need to increase brightness of electron beams especially for single-shot UED applications. We explore the utilization of field enhancement from a micron-scale single tip inside a DC gun to obtain brighter sub-pC electron beams using a nominal cathode electric field of several MV/m. The additional field enhancement can place moderate voltage sources on par with the highest gradient devices and allow improved performance presently not possible in the existing photoemission guns.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB128
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Paper

Title

Page

Cornell Laboratory for High Intensity, Ultra-Bright and Polarized Electron Beams

551

L. Cultrera, A.C. Bartnik, I.V. Bazarov, C.M. Gulliford, P. Gupta, H. Lee, S.A. McBride, T.P. Moore
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Funding: This work has been funded by the National Science Foundation (Grant No. PHY-1416318) and Department of Energy (Grants No. DE-SC0014338, No. DE-SC0011643 and No. DE-SC0016203).
We report on the current activities pursued at Cornell University for the production of electron beams tailored to a wide range of applications. We have developed the expertise to grow many different type of high quantum efficiency photocathode belonging to the alkali antimonide family. Those materials are ideal candidates to produce high intensity beam with average currents in the mA range. When operated near threshold at cryogenic temperature in transmission mode they can also generate the electron beams needed to perform ultrafast electron diffraction of bio molecules. We have recently expanded our facility with a Mott polarimeter to include the capability to measure polarization of the electron beam. The photocathode lab is being complemented by a dedicated photo-gun laboratory to test the photocathode properties in a real environment and to perform measurement of the beam properties under new and yet unexplored operating conditions.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPIK023

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPAB126

Multi-objective Genetic Optimization of Single Shot Ultrafast Electron Diffraction Beamlines

1615

C.M. Gulliford, A.C. Bartnik, I.V. Bazarov
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
J.M. Maxson
UCLA, Los Angeles, California, USA

We present the results of multi-objective genetic algorithm optimizations of two single-shot ultrafast electron diffraction (UED) beam lines. The first is based on a 225 kV dc gun featuring a novel cryocooled photocathode system and buncher cavity. The second uses a 100 MV/m 1.6 cell normal conducting rf (NCRF) gun, as well as a 9 cell 2 Pi/3 bunching cavity placed between two solenoids. Optimizations of the transverse projected emittance as a function of bunch charge are presented and discussed in terms of the scaling laws derived in the charge saturation limit. Additionally, optimization of the transverse coherence length as a function of final rms bunch length at the sample location have been performed. These results demonstrate the viability of the approaches taken for both beamlines studied as well as the use of using genetic algorithms in the design and operation of UED beamlines.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB126

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPAB128

Single Photoemitter Tips in a DC Gun: Limiting Aberration-induced Emittance

1622

I.V. Bazarov, L. Cultrera, C.M. Gulliford, H. Lee
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
H.K. Fung
Cornell University, Ithaca, New York, USA
J.M. Maxson
UCLA, Los Angeles, California, USA

Ultrafast electron diffraction (UED) offers unique advantages over x-ray diffraction, like stronger scattering cross-section, versatility in sample types and ability to offer smaller apparatus foot print. There is a growing need to increase brightness of electron beams especially for single-shot UED applications. We explore the utilization of field enhancement from a micron-scale single tip inside a DC gun to obtain brighter sub-pC electron beams using a nominal cathode electric field of several MV/m. The additional field enhancement can place moderate voltage sources on par with the highest gradient devices and allow improved performance presently not possible in the existing photoemission guns.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB128

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)