Electrode system

The electrode system for the offline beam time after set-up in Mainz in 2012

aSPECT electrode system 2012

From left to right: Ch. Schmidt (diploma student), A. Wunderle (PhD student), Dr. M. Beck (on the ladder)

The main components are

  1. The decay volume (DV) where some of the neutrons decay.
  2. The analyzing electrode (AP) for the retardation of the decay protons.
  3. The detector on high voltage for reacceleration and counting of the transmitted protons.

The DV and AP are made of plane surfaces in order to get a well-defined and reproducible work function of the electrode surfaces. This also facilitates the measurement of the work function of these surfaces with a standard commercial Kelvin probe.

The decay volume

New DV since 2011

The analyzing electrode

The AP electrode during its first assembly in 2013

 First assembly of the new AP electrode 2013

Students having fun with the new AP electrode. Clearly visible is the octagonal structure due to the plane surfaces in contrast to previous measurements at aSPECT using a cylindrical AP electrode.

Other important components are

ExB Electrodes (lExB, E15, uExB) to remove stored charged particles from the electrode system.

The mirror electrode to also detect downward going protons.