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ACKNOWLEDGMENTS
This article comprises parts of the Ph.D. thesis works of P.W.,
S.S., and D.P., submitted or to be submitted at the Ruprecht-Karls-
Universität Heidelberg, Germany.Funding:This work was supported

by the Max Planck Society, the Weizmann Institute of Science, the

German Science Foundation (DFG Wo 1481/2-1 and DFG GE 2183/3-1),

and the European Research Council (Starting Grant StG 307163).

Author contributions:K.B., D.Z., and A.W conceived the original

idea. K.B., S.G., H.K., D.Z., and A.W. provided financial support. O.N.

and A.W. led the preparations, modeling, measurements, and analysis.

O.N., P.W., D.P., Á.K., S.S., C.K., M.G., and A.W. performed the

measurements and analyzed the data. O.N., P.W., D.P., C.K., D.A.O.,

M.R., A.S., A.S.T., S.V., and A.W. contributed to the design and

realization of the CSR electron cooler and photocathode electron gun.

O.N., S.S., A.B., C.K. and A.W. contributed to the design and

realization of the detector. All other authors contributed to

development and realization of further tools and methodology, as well

as to preparatory measurements directly relevant for this work.

O.N., H.K., and A.W. wrote the manuscript. All authors commented on

the final manuscript.Competing interests:The authors declare no

competing interests.Data and materials availability:The underlying

data are available in the supplementary materials and Edmond, the

Max Planck Society repository ( 32 ).

SUPPLEMENTARY MATERIALS

science.sciencemag.org/content/365/6454/676/suppl/DC1

Materials and Methods

Figs. S1 and S2

Table S1

References ( 33 – 38 )

12 April 2019; accepted 1 July 2019

Published online 18 July 2019

10.1126/science.aax5921

Novotnýet al.,Science 365 , 676–679 (2019) 16 August 2019 4of4

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