6.2.3 Conversion Surfaces

Three conversion surfaces were available:

  1. B-doped polished CVD diamond grown on Si(100), round, 25.5 mm in diameter
  2. MgO (100) single crystal, polished (roughness < 5nm\( _{rms} \)), square sample 25mm x 25mm, supplied by Mateck [7].
  3. 200nm BaZrO\( _{3}\) on W(110) deposited using the pulsed laser deposition method [40], square sample 25mm x 25mm approximately.
Two sample holders were built for the two different sample sizes (round and square). No provision was made for heating or cleaning the sample after installation in the extraction lens.

For calibration measurements a transparent grid replacing the conversion surface was available. After reversing the voltages on the extraction lens positive ions from the ion source of CASYMS were directly injected into the lens instead of the negative ions produced at the conversion surface. Using the grid we could benefit from the much higher ion beam intensities to measure the characteristics of the lens and the TOF.

March 2001 - Martin Wieser, Physikalisches Institut, University of Berne, Switzerland