Upgrade of the nuclear microprobe at the Ion Beam Center at HZDR


Upgrade of the nuclear microprobe at the Ion Beam Center at HZDR

Munnik, F.; Hanf., D.; Heller, R.

The nuclear microprobe that was installed in 1994 at the Ion Beam Center of the Helmholtz-Zentrum Dresden-Rossendorf [1], has been in operation up to 2014 with only minor changes. After 20 years it became necessary to make an upgrade to replace old components and bring the setup up to current standards of technology and good working practice.
The major drawback of the old system was the optical microscope, especially the poor resolution and low contrast and brightness. However, a good optical image is essential to localise the areas of interest on, for example, large geological samples. Since the focused beam of MeV ions and the corresponding detectors is the principal investigative tool, any other equipment such as an optical microscope has to be designed around this device. A new microscope has been installed for which the first light-collecting lens is mounted directly into the chamber at only a few centimetres from the sample. The light is then guided over large mirrors and focussed on a CCD camera outside the sample chamber. The illuminating light is fed in through the lenses instead of using an external light source as in the old system. In addition, there is also a light source opposite to the microscope, allowing transmission illumination including through a polarising filter making polarised imaging possible.
Other improvements concern the control of the scanning system as well as the control and monitoring of all relevant experimental parameters. The control of the scan magnets is done by custom-designed hardware to guarantee real-time execution of the scanning without the need for a computer running a real-time operating system. Controlling and monitoring of the experiment are implemented to facilitate easy and secure operation of the microprobe by the user with special emphasis on operation by un-experienced users, since the device is part of the user facility IBC. All standard IBA techniques like PIXE, PIGE, RBS, NRA, ERDA and STIM are available and, in addition, a Channeltron detector has been installed to detect secondary electrons that allow quick imaging of the measurement area.
Technical details and first test measurements with the new system are presented.

[1] F. Herrmann, D. Grambole, Nucl. Instr. Meth. B 104 (1995) 26.

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Publ.-Id: 24886