MLZ is a cooperation between:

Technische Universität München> Technische Universität MünchenHelmholtz-Zentrum Geesthacht> Helmholtz-Zentrum GeesthachtForschungszentrum Jülich> Forschungszentrum Jülich
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MLZ (eng)

Lichtenbergstr.1
85748 Garching

SPM

Scanning positron microscope

The Munich scanning positron microscope permits positron lifetime measurements with a lateral resolution in the μm range and within an energy range of 1 – 20 keV. Thus, this instrument enables the measurement of high resolved 3D defect maps. Until today, the SPM was operated only in the laboratory at the Universität der Bundeswehr in Munich and was therefore limited by the long measurement times of several days per 2D-scan due to the low intensity of the positron beam produced by a standard 22Na source. This disadvantage will be overcome by installing the SPM at the high intensity positron beam at NEPOMUC.

Therefore, the SPM interface was designed and tested successfully [1]. This device converts the continuous beam of NEPOMUC to a high-brightness, pulsed positron beam, which matches the demands of the SPM. Recently, a sample chamber was connected to the SPM interface which enables spatially resolved positron lifetime measurements with a lateral resolution in the range of 0.1 mm.

[1] Piochacz, C et al., Physica status solidi / C, 4(10), 4028-4031 (2007).

Technical Data

Beam properties SPM / SPM Interface

  • Positron implantation energy: < 20 keV / < 10 keV
  • Beam-Spot: < 1 μm / ≈ 0.1 mm
  • Count rate: > 2000 cps / > 4000 cps
  • Time-Window: 20 ns
  • Time-Resolution: < 250 ps
  • Peak/ Background: > 5000 : 1 / > 2000 : 1

Typical measurement times

  • SPM: ≈ 1 day for one 2D-Scan (12 × 12 μm2)
  • SPM interface: ≈ 0.5 day for one 2D-Scan (1 x 1 mm2)

Instrument Scientist

Marcel Dickmann
Phone: +49 (0)89 289-11770
E-Mail:

Johannes Mitteneder
Phone: +49 (0)89 289-54722
E-Mail:

Operated by

UniBW
TUM

Citation of the instrument

Heinz Maier-Leibnitz Zentrum. (2015). SPM: Scanning positron microscope. Journal of large-scale research facilities, 1, A26. http://dx.doi.org/10.17815/jlsrf-1-53

For citation please always include the DOI.

Gallery

SPM
SPM
© W. Schürmann, TUM
Time spectrum
Time spectrum

Time spectrum of the threefold bunched and triply moderated positron beam.

Insert: intensity distribution of the beam focused by a long focal electric lens.

SPM scheme
SPM scheme

The optical column of the SPM (light gray) connected to the SPM interface. Both is borne by a special frame construction (light yellow), which ensures the vibration decoupling via heavy damper (dark gray, only one shown).

MLZ is a cooperation between:

Technische Universität München> Technische Universität MünchenHelmholtz-Zentrum Geesthacht> Helmholtz-Zentrum GeesthachtForschungszentrum Jülich> Forschungszentrum Jülich