A leak check was performed on the module on October 27/10/2011 by David Wang and was reported to Bevan Moss but it never made it into the Elog system. This entry is to summarize the results of that testing. All circuits were pressurized to 80 psi with helium and every line except the tube heater (+) showed no or small responses as experienced before. The tube heater line had a slightly larger response under the conditions summarized below:

Varian 959

Base Pressure                   7.0 x 10^-3 Torr

Base Leak Rate                  7.5 x 10^-9 atm cc/sec

Gauges

IG1                                         2.0 x 10^-6 Torr

PNG5                                    9.6 x 10^-6 Torr

PNG4 (C.S.)                        2.4 x 10^-5 Torr

Convectron (Back line) 20mTorr

 The leak rate quickly climbed to 3.0 x 10^-8 atm cc/sec then constantly climbed to 1.4 x 10^-7 atm cc/sec for 2 minutes. David repeated this test again at the end of the leak test and found the same results. In the past we have called this a leak and attempted to find its location and repair it. David believes that this isn’t a real leak as we have been able to achieve very good vacuum on TM4 all year and that we do not normally touch the feed through stem on this circuit. This result makes me nervous as the total differential is roughly the same as that we found on the UCx#2 run(which was at a higher vacuum).

The result of this test caused the module to move back to the hot cell for further more localized leak checking.