2025/01/15 by Maximilian Herbert, Tobias Eggert, J. Enders +5 · 1 voice · 1 citation
Engineering · Physics and Astronomy · Medicine · #Photocathodes and Microchannel Plates #Particle Detector Development and Performance #Radiation Therapy and Dosimetry
paper · doi:10.1103/physrevaccelbeams.28.013401
openalex publication_date 2025/01/15 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/31
GaAs-based photocathodes are the only viable source capable of providing spin-polarized electrons for accelerator applications. This type of photocathode requires a thin surface layer, in order to achieve negative electron affinity (NEA) for efficient photoemission. However, this layer is vulnerable to environmental and operational effects, leading to a decay of the quantum efficiency <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"> <a:mi>η</a:mi> </a:math> characterized by a decay constant or lifetime <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" display="inline"> <c:mi>τ</c:mi> </c:math> . In order to increase <e:math xmlns:e="http://www.w3.org/1998/Math/MathML" display="inline"> <e:mi>τ</e:mi> </e:math> , additional agents can be introduced during the activation procedure to improve the chemical robustness of the surface layer. This paper presents the results of recent research on Li as an enhancement agent for photocathode activation using Cs and <g:math xmlns:g="http://www.w3.org/1998/Math/MathML" display="inline"> <g:msub> <g:mi mathvariant="normal">O</g:mi> <g:mn>2</g:mn> </g:msub> </g:math> , forming Cs- <j:math xmlns:j="http://www.w3.org/1998/Math/MathML" display="inline"> <j:mrow> <j:msub> <j:mrow> <j:mi mathvariant="normal">O</j:mi> </j:mrow> <j:mrow> <j:mn>2</j:mn> </j:mrow> </j:msub> </j:mrow> </j:math> -Li as an enhanced NEA layer. Measurements yielded an increase in lifetime by a factor of up to <m:math xmlns:m="http://www.w3.org/1998/Math/MathML" display="inline"> <m:mrow> <m:mn>19</m:mn> <m:mo>±</m:mo> <m:mn>2</m:mn> </m:mrow> </m:math> and an increase in extracted charge by a factor of up to <o:math xmlns:o="http://www.w3.org/1998/Math/MathML" display="inline"> <o:mrow> <o:mn>16.5</o:mn> <o:mo>±</o:mo> <o:mn>2.4</o:mn> </o:mrow> </o:math> , without significant reduction of <q:math xmlns:q="http://www.w3.org/1998/Math/MathML" display="inline"> <q:mi>η</q:mi> </q:math> . This performance is equal to or better than that reported for other enhanced NEA layers so far.