title: The source-sample stage of the new two-dimensional angular correlation of annihilation radiation spectrometer at Technische Universität München.
abstract: Angular correlation of annihilation radiation (ACAR) is a well established technique for the investigation of the electronic structure. A major limitation of ACAR studies is the available positron flux at a small spot on the sample. For this reason, the focus of this work is put on the discussion of a newly developed source-sample stage of the new 2D-ACAR spectrometer at Technische Universität München which uses an optimized static magnetic field configuration to guide the positrons onto the sample. The achieved spot diameter is d(FWHM) = 5.4 mm, with a high efficiency over the whole energy spectrum of the (22)Na positron source. The implications of the performance of the source-sample stage are discussed with regard to 2D-ACAR measurements of single crystalline α-quartz, which serves as a model system for the determination of the total resolution. A value of (1.53 × 1.64) mrad(2) FWHM was achieved at room temperature.
authors: Technische Universität München, Lehrstuhl E21, Garching, Germany. hubert.ceeh@frm2.tum.de
authors: Hubert
authors: H
authors: Ceeh
authors: Josef Andreas
authors: JA
authors: Weber
authors: Michael
authors: M
authors: Leitner
authors: Peter
authors: P
authors: Böni
authors: Christoph
authors: C
authors: Hugenschmidt