Positron Research Group -|-|- St Olaf College, Northfield, MN, USA


What is a Positron? Crash Course for Beginners

Gas Scattering Experiment
Micelle Experiment
About Our Group
Frisbee Golf

Positron Research Group
Science Center 155
1520 St. Olaf Avenue
Northfield, MN 55057

Dr. Jason Engbrecht
507-646-3968 FAX


Anna Legard '08

Dan Endean '09

David Green '09





The summer of 2003 was a productive one for us as we began to build the positronium-gas-scattering experiment from ground zero. Our most important result was the testing of the 2D data acquisition system.

An example of the simultaneous measurement of doppler broadening and timing for positron annihilation.

An example of a 2D histogram of the energy and timing data acquired with the apparatus described is shown to the right. Positrons were obtained from an encapsulated Na-22 source and therefore no significant lifetime (> 10 ns) is observed. The spread in the data in the time dimension is therefore essentially a measure of the timing resolution and has a FWHM of approximately 15 ns. The energy resolution was observed with a Cs-137 source and a FWHM of 1.9 keV at 600 keV was obtained.

In 2004, further work was done on the apparatus, acquisition electronics and software. Early in 2005, we are seeing some preliminary data, while making some final adjustments on the apparatus.

In 2006 we have worked to build a new setup, including a new cooling system and power supply. With this new equipment we've continued taking data and attempting to impove analysis of our data. Recently we've improved data rate through a mixture of gases.


Let's see the micelle page! --->