An UHV setup for surface and interface characterization by nuclear methods

Within the frame of a collaboration program an Ultra High Vacuum (UHV) setup has recently been installed at the Department of Applied Physics in Bucharest. A schematic drawing of the UHV chamber is shown.The pumping systems consist of a first stage (sluice) evacuated by a turbomolecular pumping unit and a second stage (main chamber) evacuated by an ion - getter pump and a titan sublimation pump. The pressure is measured with a Bayard - Alpert gauge allowing for vacuum control during the backing procedure. Typical pressure of 2 x 10 -10 mbar have been obtained after backing for 24 hours at 150 deg. C by using the turbopump unit and the titan sublimation pump. The basic characteristics of the UHV chamber are the following: 1. In situ sample preparation facilities are provided to prepare layers of solid deposited materials; 2. A transfer system allows the movement of the sample from the preparation place to several characterization positions, while maintaining UHV conditions; 3. Sample temperature is controlled rigorously (within 1 K) from 100 K (LN2 cooling) to 1000 K at any place; 4. Solid state detectors allow for Rutherford Back Scattering (RBS) analysis and γ - ray detectors are mounted in close geometry for perturbed angular correlation (PAC) measurements