IPAC2021 - List of Authors (Noakes, T.C.Q.)

Paper	Title	Page
WEPAB111	Controlled Degradation by Oxygen Exposure in the Performance of a Ag (100) Single-Crystal Photocathode	2856
	L.A.J. Soomary, C.P. Welsch The University of Liverpool, Liverpool, United Kingdom L.B. Jones, T.C.Q. Noakes STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
	The search for high-performance photocathode electron sources is a priority in the accelerator science community. The surface characteristics of a photocathode define many important factors of the photoemission including the work function, intrinsic emittance, and quantum efficiency of the photocathode. These factors in turn define the electron beam performance which is measurable as normalized emittance, brightness, and energy spread. Strategies for improving these parameters vary, but understanding and influencing the relevant cathode surface physics which underpin these attributes is a primary focus for the electron source community. As such, pure metal photocathodes and their performance at UV wavelengths are of interest as seen at the LCLS at SLAC and CLARA at Daresbury. We present performance data for an Ag (100) single-crystal photocathode under illumination at 266 nm wavelength, with known levels of surface roughness, using our Transverse Energy Spread Spectrometer (TESS)** both at room and cryogenic temperatures. Crucially our data shows the effect of progressive degradation in the photo-cathode performance as a consequence of exposure to controlled levels of oxygen. * D.H. Dowell, et al., Nucl. Instr. and Meth. A (2010), doi:10.1016/j.nima.2010.03.104 Appl. Phys. Lett. 89, 224103 (2006); doi:10.1063/1.2387968 * Proc. FEL’13, TUPPS033, 290-293
	Poster WEPAB111 [0.866 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB111
About •	paper received ※ 20 May 2021 paper accepted ※ 22 June 2021 issue date ※ 31 August 2021
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPAB112	Performance Characterisation of a Cu (100) Single-Crystal Photocathode	2860
	L.A.J. Soomary, D.P. Juarez-Lopez, C.P. Welsch The University of Liverpool, Liverpool, United Kingdom L.B. Jones, T.C.Q. Noakes STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
	The search for high performance photocathode electron sources is a priority in the accelerator science community. The surface characteristics of a photocathode define important factors of the photoemission including the intrinsic emittance, the quantum efficiency and the work function of the photocathode. These factors in turn define the electron beam performance which are measurable as emittance, brightness and energy spread. We have used ASTeC’s Multiprobe (SAPI)* to characterise and analyse photocathode performance using multiple techniques including XPS, STM, and LEED imaging, and their Transverse Energy Spread Spectrometer (TESS)** to measure mean transverse energy (MTE). We present characterisation measurements for a Cu (100) single-crystal photocathode sample with data from SAPI confirming the crystallographic face and showing surface composition and roughness, supported by data from TESS showing the photocathode electron beam energy spread. * B.L. Militsyn, 4-th EuCARD2 WP12.5 meeting, Warsaw, 14-15 March 2017 **Proc. FEL’13, TUPPS033, 290-293
	Poster WEPAB112 [0.814 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB112
About •	paper received ※ 19 May 2021 paper accepted ※ 12 July 2021 issue date ※ 22 August 2021
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Page

Controlled Degradation by Oxygen Exposure in the Performance of a Ag (100) Single-Crystal Photocathode

2856

L.A.J. Soomary, C.P. Welsch
The University of Liverpool, Liverpool, United Kingdom
L.B. Jones, T.C.Q. Noakes
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

The search for high-performance photocathode electron sources is a priority in the accelerator science community. The surface characteristics of a photocathode define many important factors of the photoemission including the work function, intrinsic emittance, and quantum efficiency of the photocathode. These factors in turn define the electron beam performance which is measurable as normalized emittance, brightness, and energy spread*. Strategies for improving these parameters vary, but understanding and influencing the relevant cathode surface physics which underpin these attributes is a primary focus for the electron source community**. As such, pure metal photocathodes and their performance at UV wavelengths are of interest as seen at the LCLS at SLAC and CLARA at Daresbury. We present performance data for an Ag (100) single-crystal photocathode under illumination at 266 nm wavelength, with known levels of surface roughness, using our Transverse Energy Spread Spectrometer (TESS)*** both at room and cryogenic temperatures. Crucially our data shows the effect of progressive degradation in the photo-cathode performance as a consequence of exposure to controlled levels of oxygen.
* D.H. Dowell, et al., Nucl. Instr. and Meth. A (2010), doi:10.1016/j.nima.2010.03.104
** Appl. Phys. Lett. 89, 224103 (2006); doi:10.1063/1.2387968
*** Proc. FEL’13, TUPPS033, 290-293

Poster WEPAB111 [0.866 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB111

About •

paper received ※ 20 May 2021 paper accepted ※ 22 June 2021 issue date ※ 31 August 2021

Export •

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

WEPAB112

Performance Characterisation of a Cu (100) Single-Crystal Photocathode

2860

L.A.J. Soomary, D.P. Juarez-Lopez, C.P. Welsch
The University of Liverpool, Liverpool, United Kingdom
L.B. Jones, T.C.Q. Noakes
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

The search for high performance photocathode electron sources is a priority in the accelerator science community. The surface characteristics of a photocathode define important factors of the photoemission including the intrinsic emittance, the quantum efficiency and the work function of the photocathode. These factors in turn define the electron beam performance which are measurable as emittance, brightness and energy spread. We have used ASTeC’s Multiprobe (SAPI)* to characterise and analyse photocathode performance using multiple techniques including XPS, STM, and LEED imaging, and their Transverse Energy Spread Spectrometer (TESS)** to measure mean transverse energy (MTE). We present characterisation measurements for a Cu (100) single-crystal photocathode sample with data from SAPI confirming the crystallographic face and showing surface composition and roughness, supported by data from TESS showing the photocathode electron beam energy spread.
* B.L. Militsyn, 4-th EuCARD2 WP12.5 meeting, Warsaw, 14-15 March 2017
**Proc. FEL’13, TUPPS033, 290-293

Poster WEPAB112 [0.814 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB112

About •

paper received ※ 19 May 2021 paper accepted ※ 12 July 2021 issue date ※ 22 August 2021

Export •

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