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Siddharth Karkare & Laurent Boulet

Siddharth Karkare, left, and Laurent Boulet '14 in the Newman Hall photocathode research lab.

Physics graduate student Siddharth Karkare is the first author on a recent Physical Review Letters publication reporting new interdisciplinary research on "Ultrabright and Ultrafast III-V Semiconductor Photocathodes" that could dramatically improve accelerator performance (1). The photocathode is the source of electrons that become the x-ray source in the case of a light source like a free-electron laser or an energy recovery linac. Karkare, with faculty advisor Ivan Bazarov (Cornell Physics Department), has been using a variety of tools to simulate, design and fabricate novel materials needed to make state-of-the-art photocathode sources. This publication presents new simulation tools that will help design better materials for future applications. The Cornell Chronicle recently highlighted this work, mentioning how the groups' efforts involved working at three facilities: "Newman Lab, where Karkare and colleagues have built various photocathode surface and electron beam diagnostics all maintained at ultra-high vacuum comparable to the vacuum in deep space; Wilson Synchrotron Lab, home of the Cornell High Energy Synchrotron Source (CHESS), where photocathodes can be tested in an actual accelerator; and Phillips Hall, where a technique called molecular beam epitaxy is used to grow thin materials for use as photocathodes. (2)" Prior experimental work at CHESS utilized scanning x-ray fluorescence methods to characterize and improve GaAs and multi-alkali photocathodes grown in Newman and Phillips facilities.


[1] Karkare S, Boulet L, Cultrera L, Dunham B, Liu XH, Schaff W, et al., "Ultrabright and Ultrafast III-V Semiconductor Photocathodes", 2014. Mar 3;112(9). PubMed PMID: WOS:000332169000011. English.

[2] Glaser LB, "Grad student aims to improve particle accelerators", 2014. Available from:



Submitted by: Ernest Fontes, CHESS, Cornell University