Chad and i did a leak check on TM4 heat shield circuit with new NiO#1 target installed. It took about 40 mins(much longer than usual) to pump down the circuit to leak rate 0.6x E-9atm.cc/sec and 0.0x E-4 torr o leak detector.

All vacuum lines and joints which connected to the leak detector had been helium sprayed and they are leak  tight.Chad sprayed helium on each VCR joints for 2 seconds every time. During 1min waiting time, there is no any response on leak detector. Chad repeated same test again for double checking and we got same result. Chad finally flushed the helium around the target heat shield for 10 seconds.we waited for 1minute and found no response on the leak detector. The heat shield circuit is leak tight at this stage. I will do a helium pressure test on this circuit when TM4 is in CS and under vacuum.