TY - JOUR

T1 - The measurement of photocathode transverse energy distribution curves (TEDCs) using the transverse energy spread spectrometer (TESS) experimental system

AU - Jones, L. B.

AU - Juarez-Lopez, D. P.

AU - Scheibler, H. E.

AU - Terekhov, A. S.

AU - Militsyn, B. L.

AU - Welsch, C. P.

AU - Noakes, T. C.Q.

N1 - ACKNOWLEDGMENTS: The authors gratefully acknowledge work done by Ph.D. students Chris Benjamin (University of Warwick) and Liam Soomary (University of Liverpool) to clean and then characterize these singlecrystal photocathode samples using XPS and STM and also to measure the detector linearity. The work was partly funded by the Mexican government through the Consejo Nacional de Ciencia y Tecnologia (https://www.conacyt.gob.mx/)

PY - 2022/11/1

Y1 - 2022/11/1

N2 - The minimum achievable particle beam emittance in an electron accelerator depends strongly on the intrinsic emittance of the photocathode electron source. This is measurable as the mean longitudinal and transverse energy spreads in the photoemitted electron beam (MLE and MTE respectively); consequently, MLE and MTE are notable figures of merit for photocathodes used as electron sources in particle accelerators. The overall energy spread is defined by the sum of the MTE and the MLE, and the minimization of MTE is crucial to reduce emittance and thus generate a high-brightness electron beam. Reducing the electron beam emittance in an accelerator that drives a Free-Electron Laser (FEL) delivers a significant reduction in the saturation length for an x-ray FEL, thus reducing the machine's construction footprint and operating costs while increasing the x-ray beam brightness. The ability to measure the transverse energy distribution curve of photoelectrons emitted from a photocathode is a key enabler in photocathode research and development that has prompted the Accelerator Science and Technology Centre (ASTeC) at the STFC Daresbury Laboratory to develop the Transverse Energy Spread Spectrometer to make these crucial measurements. We present details of the design for the upgraded TESS instrument with measured data for copper (100), (110), and (111) single-crystal photocathodes illuminated at UV wavelengths around 266 nm.

AB - The minimum achievable particle beam emittance in an electron accelerator depends strongly on the intrinsic emittance of the photocathode electron source. This is measurable as the mean longitudinal and transverse energy spreads in the photoemitted electron beam (MLE and MTE respectively); consequently, MLE and MTE are notable figures of merit for photocathodes used as electron sources in particle accelerators. The overall energy spread is defined by the sum of the MTE and the MLE, and the minimization of MTE is crucial to reduce emittance and thus generate a high-brightness electron beam. Reducing the electron beam emittance in an accelerator that drives a Free-Electron Laser (FEL) delivers a significant reduction in the saturation length for an x-ray FEL, thus reducing the machine's construction footprint and operating costs while increasing the x-ray beam brightness. The ability to measure the transverse energy distribution curve of photoelectrons emitted from a photocathode is a key enabler in photocathode research and development that has prompted the Accelerator Science and Technology Centre (ASTeC) at the STFC Daresbury Laboratory to develop the Transverse Energy Spread Spectrometer to make these crucial measurements. We present details of the design for the upgraded TESS instrument with measured data for copper (100), (110), and (111) single-crystal photocathodes illuminated at UV wavelengths around 266 nm.

UR - https://www.scopus.com/inward/record.url?eid=2-s2.0-85143301789&partnerID=40&md5=01d7ff0576f57c7d13b4b6af4a144c89

UR - https://www.mendeley.com/catalogue/b37d0c55-4c7a-3b55-8bc3-42ecb1709824/

U2 - 10.1063/5.0109053

DO - 10.1063/5.0109053

M3 - Article

C2 - 36461497

VL - 93

JO - Review of Scientific Instruments

JF - Review of Scientific Instruments

SN - 0034-6748

IS - 11

M1 - 113314

ER -