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Forschungszentrum Jülich - Research in Jülich 3_2012

er, the usual method would not have been successful – a fact Stadler has demon- strated in experiments using powder sam- ples at the SPHERES neutron backscatter- ing instrument in Garching, which were supported by Dr. Gerald Schneider from JCNS. “Apparently, wetting the powders is not enough to make them fully biologically active,” concludes Stadler. COMPUTER SIMULATIONS After the neutron scattering experi- ments, it was initially still open to specu- lation which part of the haemoglobin was responsible for adapting to the body temperature during the process of evolution. After all, haemoglobin consists of more than 550 amino acids with a total of around 6000 atoms. The fact that the basic structure of the haemoglobin is the same in different living organisms made it all the more diffi- cult to find an answer to this question. 38°37°36° As building blocks of atomic nuclei, neutrons are subject to the laws of quantum mechanics. They can behave both as a wave and as a particle. The waves are about as long as the distances between atoms in crystals. Those waves scattered at the atoms inter- fere with each other. Similar to the ripples created by throw- ing a stone into a pool of water, some of these waves ampli- fy each other while others cancel each other out. This results in patterns that provide information on the ar- rangement of atoms in the crystal. With the help of this principle, neutron researchers are able to analyse struc- tures, including those of powders and giant molecules, as if under a high-resolution microscope. In other measurements, the behaviour of neutrons resembles that of particles. When they collide with atoms, they absorb and release kinetic energy, like billiard balls. The intensity with which they are accelerated or decelerated depends on the velocity of the atoms, among other factors. This is why researchers can use neutrons to study dynamic processes in materials. Since these processes often take no more than a trillionth of a second, but sometimes hundredths of a second, different instruments are necessary: backscattering spectrometers, time-of-flight spectrome- ters and spin-echo spectrometers are all specifically designed for de- fined time and length scales. Neutrons also have another useful property: they possess a magnetic moment known as the spin. Comparable to a compass needle that mea- sures the earth’s magnetic field, the neutron spin is influenced by the atomic orientation of the elementary magnetic moments in a material. Researchers can therefore also use neutrons to explore the magnetic properties of materials. The Methods of Neutron Researchers The SPHERES neutron backscattering in- strument in Garching near Munich Research in Jülich 3|201210 HUMAN 36–37 °C The JCNS

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