Berlin 2012 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 35: Poster Session II (Polymeric biomolecular films; Nanostructures; Electronic structure; Spin-orbit interaction; Phase transitions; Surface chemical reactions; Heterogeneous catalysis; Particles and clusters; Surface magnetism; Electron and spin dynamics; Surface dynamics; Methods; Electronic structure theory; Functional molecules)

O 35.59: Poster

Dienstag, 27. März 2012, 18:15–21:45, Poster B

Low cost low noise amplifier for charged nanoparticle beam detection — •Sebastian Schleicher, Wolfgang Rosellen, and Mathias Getzlaff — Institute of Applied Physics,University Duesseldorf

For our investigations we generate nanoparticles in the gas phase by a UHV compatible Arc Ion Cluster Source (ACIS)[1]. Nearly 50% of the beam consists of charged nanoparticles with sizes between 5 nm and 15 nm. For beam positioning and controlling, the nanoparticles are detected by a very low noise current amplifier in an embedded system. The charged nanoparticle beam has an electrical current of a couple of pico-Ampere. By amplifying this signal by a magnitude of 10¹⁵, it can be quantified. The main problem to overcome when amplifying a signal is to minimize the noise. There are four known noise sources, which need to be considered (1/f noise, 1/f² noise, Johnson-Nyquist Noise and Shot noise). We use a transimpedance amplifier. For this purpose the construction elements, like the power supply and the transimpedance amplifying circuit, were made by low-cost components. Each construction element was chosen by their highest possible noise suppression according to signal enhancement. The final signal will be converted by a 24-bit delta-sigma analog-to-digital converter. The system will be designed as an embedded microcontroller system.

[1] R.-P. Methling, V. Senz, E.-D. Klinkenberg, Th. Diederich, J. Tiggesbäumker, G. Holzhüter, J. Bansmann, K.-H. Meiwes-Broer, European Physical Journal D 16, 173 (2001)