Thursday, December 22, 2011

Beam Spot

Hi Everyone,

Got to see an actual spark inside the Pelletron, what you
see are the grid lines from the Dust Coordinate Sensor
The beam spot as seen from an astronomy camera
inserted into the middle of the beamline
Sorry for the long time between posts.  I'm trying to whip everyone in shape so they'll start blogging as well.  A couple of really exciting things have happened since my last post.  I've been working on determining why our accelerator speeds have only been up to about 10 km/s.  In order to answer this question, I've been using a CCD camera typically used for taking long exposures of the night sky and putting into the path of the beamline before our detectors.  Letting the dust hit a quartz target directly in front of this camera allows you to take images of the beam profile.  With this we were able to figure out where the beam was pointed, what it looked like, and most importantly, how to point it in the direction we want to point it in.

We were able to determine that at our current running parameters, the beam's best focus creates a spot size of about 2 mm.  By moving the back of the Pelletron we are able to steer the beam.  Using a laser attached to the Pelletron we can steer the beam to very high accuracy.  I was able to move the beam almost exactly 2 mm to the right and 3 mm down in that picture.  With this capability we made sure the beam was pointed through the detectors and then starting taking data.  The result of all that work?  We know see particles up to about 45 km/s!