MLZ is a cooperation between:> Technische Universität München> Helmholtz-Zentrum Geesthacht> Forschungszentrum Jülich
Neutron depth profiling (NDP) developed from a concept of J. P. Biersack and demonstrated in 1970 by D. Fink at the HMI (BER I) reactor. Fink imaged charged particles emitted from neutron reactions occurring in a LiF crystal. The power of the analytical technique was soon realized by several research groups around the world, including researchers from the Technische Universität München (TUM), R. Henkelmann, K. Müller, et al. in collaboration with H. Ryssel, who measured boron distributions in silicon at the ILL reactor. Nearly 50 years later, the NDP technique remains a powerful analytical tool and is being developed by TUM researchers at the FRM II on NL4b.
The principle of NDP is at first simple, a sample volume is uniformly illuminated with neutrons. In turn, neutron reactions produce monoenergetic charged particles in proportion to the abundance of nuclides such as 3He, 6Li, 10B, 14N, and others. An energy spectrum is captured from particles escaping the sample surface. Particles as deep as 10’s of micrometers are analyzed for energy, location, and time to spatially and temporally image the nuclide distribution. I will review the physics of NDP and provide examples of its applications, including helium build-up and release from fusion reactor containment vessel walls, lithium depletion in optical wave guides, boron loss in nuclear waste containment materials and, most recently, time-dependent redistribution of lithium in Li-ion batteries during charge-discharge cycles.
|Uhrzeit||14:30 - 15:30 Uhr|
|Sprecher||Dr. Gregory Downing (NIST)|