Sunday, April 01, 2007

Remnants of the Bubble Chamber from the ZGS

Thanks to one of the reader of this blog, I started paying attention to various "artifacts" around Argonne's ground, and these two in particular. It turns out that these two pieces, scattered very far from each other, were once intimately connected as part of the bubble chamber of the Zero Gradient Synchrotron (ZGS) here at Argonne that operated from the mid 1960's till early 1980's.

The ZGS had a long and illustrious history. It was one of the premier atom smasher of its time. The bubble chamber made several important observations, including the first ever detection of neutrinos in a hydrogen bubble chamber.

The world's first neutrino observation in a hydrogen bubble chamber was found Nov. 13, 1970, on this historical photograph from the Zero Gradient Synchrotron's 12-foot bubble chamber. The invisible neutrino strikes a proton where three particle tracks originate (right). The neutrino turns into a mu-meson, the long center track. The short track is the proton. The third track is a pi-meson created by the collision.

{from the caption to the figure in the link above}

Now, I've never paid that much attention to these things till now after someone asked me about them. The first one is the actual expansion omega bellows for the 12-foot bubble chamber in front of Bldg. 362 (High Energy Physics building).

Now, the piston that is responsible for the expanding the volume in the bubble chamber to create a condition that allowed for condensation can be found behind the Argonne's Visitors Center. It looks like a large, silver mushroom, and just looking at its size, you can just imagine how large this bubble chamber was. The two pictures below shows piston from different angles.

It's too bad that there's not a whole lot of written information about the significance of these objects. I would have never tried to find out what they are if someone didn't actually asked me about it. They could easily pass as "modern sculptures". Yet, they played a major role in the development of our knowledge about elementary particles.

So, if you find yourself visiting Argonne, pay attention to these objects. As you drive through the Main Gate, look to your right as you make that right turn. You'll find the piston that was the workhorse of the famous ZGS.



w7my said...

I worked on the building and development of the 12' bubble chamber in 1968-69.

The top picture is the titanium bellows that contained the vacuum around the chamber. The bellows was one of the key innovations of the chamber in that it was the largest machining of titanium at that time.

The two bottom pictures are of the piston. It was placed at the bottom of the chamber and moved down to lower the pressure of the liquid hydrogen (or deuterium)such that the vapor pressure would be low enough to allow particles to leave a trail of bubbles.

This chamber was the epitome of this generation of particle detectors and innovated many other technologies such as large cryogenic magnets, computer based control and alarms not to mention physics!

J Pope said...

I have been told by those who worked at ZGS on chamber operations that only on misty evenings, you could see the flare-off of vented hydrogen, since the flame itself (hydrogen burning in air) is in the ultraviolet. Also, in the unlikely case of a complete venting & detonation of all that hydrogen, there was an earthen berm constructed to deflect the shock wave skyward so as to avoid shattering all the nearby windows in Lemont.