Design of a positron source to be used in ultra-high vacuum

This page describes the design of a positron source to be used in positron beam systems. The design of the source capsule was developed in the Positron Laboratory of the  Department of Physics of the Martin-Luther-University Halle.

for the source capsule design:

R. Krause-Rehberg
(Univ. Halle)

For ordering a source, quotations and so on

Ms. Vuyiseka Jackso or Dr. Clive Naidoo

Radionuclide Production Group
iThemba LABS
P O Box 722, Somerset West 7130
South Africa
Tel: +27 (0)21 8431337/8433244
Fax: +27 (0)21 8433901

1. Standard Design

The source capsule is made from 5 parts: the Ti rear part ending in a post for fixing the source in the system, a small Ta cylinder (positron reflection) on which the 22-Na will be deposited, the Ti front part which has side slits for easy handling by a manipulator (see below), the Ti foil, and a Ti ring which is welded to the Ti front part to fix the foil. The foil is 5 microns thick. The front window has a diameter of 4 mm. The source is closed by a torque spanner with a defined torque. This ensures that the Ta reflection plate (which is on top of the rear part) is located very close to the Ti front window. The Ta plate has a cup-like indentation of depth 0.2mm and diameter 3.7mm.The volume is sufficient to take in a drop of 22-Na solution during the filling procedure. Each source capsule has been tested up to 5 bar overpressure. Moreover, the front part of each capsule was tested to be vacuum tight. The rear Ti part contains a cavity for the neon gas which is created during the decay of 22-Na. A small hole at the side connects this cavity with the front part.

For further details, please have a look to our poster about the source shown at SLOPOS-9 (pdf-file, click here!). Please note the the rear part of the source capsule is now only made from Ti.

(Click to the photos for enlarged view! Each of the paper squares is 5 x 5 mm.)


A drawing of the source capsule can be downloaded as a PDF file here (source.pdf  60 kB). Please note that all outer parts of the capsule are now made from Ti.

2. Small Design

To make the capsule design closer to the eralier NEN/DuPont design, we do the following changes on request:


This is the drawing for the new design. A thread can be cut to the stud (see above). Click to enlarge the picture:


Source capsule in manipulator
Source manipulator
moderator foil

For easy manipulation, we constructed a pair of pliers. This allows a save handling without the necessity of touching the source (important for radiation protection). The source can easily be taken out of the transport container and can be mounted to the system. The complete set of drawings of the source manipulator have been made at TU Munich and can be downloaded here as a PDF version (Manipulator.pdf 243 kB).  The original drawings can be downloaded here as AutoCad files for version 12, version 14 or version 2000 (thanks to Dr. Hugenschmidt).