Jai Kwan Bae

Cornell University | CU · Department of Physics

Negative Electron Affinity (NEA) activated GaAs photocathodes are the most popular option for generating a high current ([Formula: see text]1 mA) spin-polarized electron beam. Despite its popularity, a short operational lifetime is the main drawback of this material. Recent works have shown that the lifetime can be improved by using a robust Cs–Sb–...

Negative Electron Affinity (NEA) activated GaAs photocathodes are the most popular option for generating a high current (> 1 mA) spin-polarized electron beam. Despite its popularity, a short operational lifetime is the main drawback of this material. Recent works have shown that the lifetime can be improved by using a robust Cs-Sb-O NEA layer with...

The anticorrelation between quantum efficiency (QE) and electron spin polarization (ESP) from a p-doped GaAs activated to negative electron affinity is studied in detail using an ensemble Monte Carlo approach. The photoabsorption, momentum and spin relaxation during transport, and tunneling of electrons through the surface potential barrier are mod...

The anticorrelation between quantum efficiency (QE) and electron spin polarization (ESP) from a p-doped GaAs activated to negative electron affinity (NEA) is studied in detail using an ensemble Monte Carlo approach. The photoabsorption, momentum and spin relaxation during transport, and tunnelling of electrons through the surface potential barrier...

We describe measurements of the mean transverse energy (MTE) of Cs–Te photocathodes near the photoemission threshold. The MTE displays an unexpected non-monotonic behavior as the drive laser's wavelength is tuned to threshold and changes significantly as the photocathode is cooled to cryogenic temperatures. We show that a simple analytical model of...

Negative Electron Affinity (NEA) activated surfaces are required to extract highly spin-polarized electron beams from GaAs-based photocathodes, but they suffer extreme sensitivity to poor vacuum conditions that results in rapid degradation of quantum efficiency. We report on a series of unconventional NEA activations on surfaces of bulk GaAs with C...

GaAs-based photocathodes are the state-of-the-art in the production of highly spin-polarized electron beams for accelerator and microscopy applications. While various novel structures of GaAs have been shown to increase the degree of polarization and quantum efficiency, all GaAs-based photocathodes require activation to negative electron affinity (...

Negative Electron Affinity (NEA) activated surfaces are required to extract highly spin polarized electron beams from GaAs-based photocathodes, but they suffer extreme sensitivity to poor vacuum conditions that results in rapid degradation of quantum efficiency. We report on series of unconventional NEA activations on surfaces of bulk GaAs with Cs,...

The operation of photoemission electron sources with wavelengths near the photoemission threshold has been shown to dramatically decrease the minimum achievable photocathode emittance, but at the cost of significantly reduced quantum efficiency (QE). In this work, we show that for femtosecond laser and electron pulses, the increase in required lase...

The operation of photoemission electron sources with wavelengths near the photoemission threshold has been shown to dramatically decrease the minimum achievable photocathode emittance, but at the cost of significantly reduced quantum efficiency (QE). In this work, we show that for femtosecond laser and electron pulses, the increase in required lase...

Photocathodes capable of providing high intensity and highly spin-polarized electron beams with long operational lifetimes are of great interest for the next generation nuclear physics facilities like Electron Ion Colliders. We report on GaAs photocathodes activated by Cs2Te, a material well known for its robustness. GaAs activated by Cs2Te forms N...