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Medium Intensity Positron Beam: VEP and PADB

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Contact details

Schut, Henk Dr.
Applied Sciences (TNW), Section NPM2 (Neutron and Positron Methods in Materials)
Mekelweg 15, 2629 JB Delft
Tel : +31 (0)15 27 81961
E-mail : h.schut@tudelft.nl
Website : Open website

General Information


Medium Intensity Positron Beam: VEP and PADB


Experimental hall, Reactor Institute Delft, Mekelweg 15, Delft (building #50)

Key words:

Positron Annihilation, Doppler broadening, vacancy dopant complexes, voids, nano-precipitates, surfaces, interfaces and thin films

Measured quantity:

one measures the annihiliation (gamma) radiation of a positron-electron annihilation event (511 keV)

Main application:

Determination of defect depth distributions and characterization of open volume defects in sub-surface regions, in thin films and at interfaces by means of Doppler Broadening and positron (back)diffusion measurements.

Instrument specification

Medium intensity variable energy positron beam (VEP) with one- and two-detector equipment for measuring Doppler Broadening of Annihilation Radiation (PADB)

Positron source:
22Na isotope (1 GBq), magnetostatic positron beam transport.

Positron beam intensity:
1 x 105 e+ s-1

Positron beam diameter at target:
ca. 8 mm

Maximum positron energy :
30 keV 
two high purity Ge solid-state detectors, energy resolution 1.8 keV at 1.33 MeV (60Co)

Target chamber:

equipped with a closed loop cryostat (20 – 300 K), high temperature heaters (up to 1700 K), a 4 point bending device and gas permeation cell.

Other contact
Dr. S.W.H. Eijt
Section FAME (Fundamental Aspects of Materials and Energy)
Department R3 (Radiation, Radionuclides and Reactors)
Faculty of Applied Sciences
Mekelweg 15
2629 JB Delft, The Netherlands
tel: +31 (0)15 27 89053
E-mail: S.W.H.Eijt@iri.tudelft.nl

Positron facilities and positron research activities at RID and R3
The Positron Centre Delft is a research facility established at the Delft University of Technology. It provides access to the equipment (as part of RID) and scientific expertise concentrated in the sections FAME and NPM2 of the department R3 of the faculty of Applied Science.
The majority of the experimental Positron Annihilation (PA) techniques developed to this aim are based on the analysis of the annihilation radiation. They can be classified into two groups, which are distinguished by the positron’s sensitivity to the local electron density (positron lifetime, PALS) and to the local electron momentum distribution (Dopplerbroadening (PADB) and Angular Correlation (2D-ACAR)).