NEUTRON THERMOMETRY ON POLARIZED SILVER NUCLEI AT SUB-MICROKELVIN SPIN TEMPERATURES

We have utilized both neutron transmission and neutron diffraction to measure the spin polarization in a single crystal of Ag-109, whereby t he nuclear spin temperature could be obtained. Transmission of a polar ized neutron beam provides an accurate and convenient primary thermome ter. The feasibility of unpolarized neutron transmission was demonstra ted as well. The diffraction measurements were strongly influenced by extinction, whence this method had to be calibrated against another th ermometer. In this way we obtained information about extinction in the crystal.