Speaker
Description
We are going to present the upgrades developed at NREX during the shutdown time. We installed new sample environment to investigate thin film samples in H2 or D2 atmospheres: A gas handling system with remote pressure control (0-1bar), a sample chamber with both neutron and x-ray windows, and a He3 cryostat (0.5 - 300K) also with neutron and x-ray windows for simultaneous reflectometry measurements. The cryostat fits into the NREX sample electromagnet (0.5T). We developed new sample holders with spring loaded electrical contacts, which permit simultaneous neutron and x-ray reflectometry. These contacts also work at low temperatures without the need to wire-bond the samples. The contact arrangement is of van-der-Pauw type (4 contacts on a square) connected to a relais matrix, such that the current flow and voltage measurement can be freely assigned, either parallel or perpendicular to the external H field, or in crossed geometry for Hall measurements. The voltage is measured by a sensitive lock-in amplifier, and thus very low excitation currents avoiding sample heating are possible.
