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HK: Fachverband Physik der Hadronen und Kerne
HK 3: Fundamentale Wechselwirkungen
HK 3.4: Talk
Monday, March 10, 2008, 15:00–15:15, 2B
Structural and dynamical properties of solid deuterium as UCN converter material — •Markus Urban1, Erwin Gutsmiedl1, Axel Müller1, Andreas Frei1, Stephan Paul1, Christoph Morkel1, Helmut Schober2, Stephane Rols2, and Tobias Unruh3 — 1TU München — 2ILL, Grenoble — 3FRM-II, München
Ultracold neutrons (UCN) are the most promising candidates to determine the neutrons lifetime and electric dipole moment. With less than 300neV they have such little energy, that they can be confined in material containers and kept there for several hundred seconds for experiments. UCN can be produced from thermal or cold neutrons via downscattering in a solid deuterium converter.
From prototype UCN sources we know that the solid deuterium converter’s efficiency strongly depends on the specific way of crystal-preparation. Especially the freezeout process and temperature cycling (annealing) can improve the UCN output significantly. This is more or less phenomenologically observerd, but not really understood if the physical effect behind is of structural or dynamical nature.
Therefore we systematically measured the scattering function S(Q,ω) of solid deuterium with the TOFTOF time-of-flight spectrometer at the FRM-II and with the IN4-spectrometer at the ILL for different D2 samples, frozen in different manners, at different para-/ortho ratios and temperatures and before and after annealing.
In this talk some preliminary results are presented. Supported by DFG, BMBF, MLL and Cluster of Excellence Exc153.