3-D imaging -- first insights into magnetic fields

Kardjilov explains this by comparison with a medical CT scan; when a specimen is irradiated with x rays the density of the materials present alters the intensity of the light. "It's the same with our magnetic specimen, which changes the spin rotation of the neutrons", says Nikolay Kardjilov. "The equipment only allows passage of neutrons with a specific spin rotation, and this generates the contrast according to how the magnetic properties are distributed within the specimen. By rotating the specimen we can reconstruct a three-dimensional image."

Since 2005, Nikolay Kardjilov has built up the neutron tomography section at HMI and now his group is the first to use spin rotation as a measurement signal for three-dimensional imaging. Normally, neutron imaging relies on the different levels of absorption of radiation by different materials to produce contrast. The measurement of magnetic signals is a novel concept and its success lies partly in the polarisers and analysers, and the detector system, which have been developed and built by the HMI researchers.

Magnetism is one of the central research fields at HMI. To understand high temperature superconductivity, for example, it is vital to understand how magnetic flux lines are distributed and how these flux lines can be established in the material. With Kardjilov's experimental setup, it is now possible, among other things, to visualise magnetic domains in magnetic crystals three-dimensionally.

At Hahn-Meitner-Institut Berlin work about 800 employees, among them about 300 scientists. They research properties of materials, develop solar cells of new generation and practice a user facility at research reactor BER II open to the national and international community.

To 1. Januar 2009 the HMI will merge with BESSY, the Berliner Elektronenspeicherring-Gesellschaft für Synchrotronstrahlung becoming together a new research center, the Helmholtz-Zentrum Berlin for materials and energy. The Hahn-Meitner-Institut Berlin is member of the Helmholtz-Association, the biggest German research organisation. It involves 15 research institutes and 24.000 employees.

Kontakt:
HMI
Glienicker Str. 100
14109 Berlin
Dr. Nikolay Kardjilov
Tel.: +49(0)30/8062-2298
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