Berlin 2005 – wissenschaftliches Programm

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A: Atomphysik

A 14: Electron Recombination

A 14.7: Fachvortrag

Dienstag, 8. März 2005, 18:00–18:15, HU 3075

Performance of photocathode electron sources for high resolution merged beam experiments. — •Dmitry Orlov¹, Frank Sprenger¹, Michael Lestinsky¹, Udo Weigel¹, Alexander Terekhov², Dirk Schwalm¹, and Andreas Wolf¹ — ¹Max−Planck−Institut für Kernphysik, 69029 Heidelberg, Germany — ²Institute of Semiconductor Physics, 630090 Novosibirsk, Russia

An ultra cold electron source was developed for the storage ring TSR in Heidelberg to study electron-ion interactions with high energy resolution. The heart of the source is a GaAs photocathode which provides electrons with energy spreads below 10 meV [1]. Photoemitted electrons are extracted in the space charge mode and then undergo adiabatic magnetic expansion and acceleration to obtain an ultra cold electron beam which is overlapped with the stored ion beam in a straight section of the ring [2]. In the first recombination measurements of HD⁺ and H₃⁺ unprecedented low energy resonances were found demonstrating a transverse and longitudinal temperature of the electron beam of about 0.5 meV and 0.02 meV, respectively. We present the performance of the photocathode source under experimental condition, show how to get intense cold electron beams with a GaAs photocathode, and discuss the requirements for merged beam experiments to obtain energy resolution much below one meV.

[1] D.A. Orlov et al, NIM A 532 (2004) 418.

[2] F. Sprenger et al, NIM A 532 (2004) 298.