Downstairs centrifuge rotor II

Here is an illustration to better explain what's going on with the centrifuge rotor capsule.

I took the capsules back to the machine shop today. The problem was that while the machine shop drawings show a slanted inside edge, there is no 'call-out' with numbers so it's easy to miss the slant. The machine shop will fix them for us; they will put in a 30 deg inside slant. I can pick them up Tuesday afternoon.

Chatted a bit with Carlheinz. His office is being remodeled and they are having walls put in to keep out the dust and noise. They've thrown out cabinets, papers, and books that have been there for as long as 40 years, making way for computers and the electronic age.

Diagnosing glovebox pump

Today Alan helped me use a pressure gauge to diagnose the glovebox pump. We concluded that our pump is very bad. Our pump only pumps down to 80 Torr whereas the KGB pump goes down to 20-30 mTorr. We didn't find any major leaks in the glovebox system itself.

Test details:
Our pump connected to gauge, with outlet filter: 100 Torr
Our pump connected to gauge w/o outlet filter: 80 Torr
--> we might need new outlet filter
KGB pump connected to gauge: 20-30 mTorr
KGB pump connected to gauge + glovebox: 20-30 mTorr
KGB pump connected to gauge + glovebox + mini-antechamber: 20-30 mTorr

Opening valve slowly (pressure not exceeding 100 Torr), it took about 4 minutes to pump down the mini-antechamber.

Tomorrow I will set up the KGP pump semi-permanently so that we can use it while we have our pump repaired.

Outstanding physics major

George Margulis has been awarded the David S. Levine award for outstanding junior physics major. According to the physics department website, this award recognizes "academic breadth and demonstrated abilities in experimental physics."

Congratulations George!

2007 Applied Physics Commencement

Hi.

Nancy and I enjoyed the commencement.

Here is the picture of us.

Downstairs centrifuge rotor

I'd been having some trouble spinning my growths using the new centrifuge downstairs. Somehow, when depositing my growth into the centrifuge capsule, it would often get stuck on the lip of the capsule and I would waste valuable seconds poking it to make it go in. This happened several times before I realized that the capsules had not been machined exactly to specifications. While the upstairs, original centrifuge capsules have slanted lips, the ones on the new capsules are completely horizontal - thus providing a ledge on which my growths can get stuck.

Since I realized this, I've been bringing one of the old capsules downstairs to do my spin. Eventually I'll go to the machine shop to see if the new capsules can be fixed.