An opened up chamber to detect <a href="https://en.wikipedia.org/wiki/Alpha_particle" class="extiw" title="en:Alpha particle">alpha particle</a> with Pu-242 on the filter
<a href="https://de.wikipedia.org/wiki/User:Cuchullain" class="extiw" title="de:User:Cuchullain">Cuchullain</a>
2007-05-04
own work by Cuchullain <br><small>German WIkipedia: <a class="external free" href="https://de.wikipedia.org/wiki/Bild:Alphaspektroskopie.JPG">http://de.wikipedia.org/wiki/Bild:Alphaspektroskopie.JPG</a></small>