Connected leak detector to TM4 and CS vacuum system. The vacuum readings on TM4 and CS:PNG4 3.6 xE-6 Torr, IG1 2.3xE-6torr, IG4(diagnostic box) 3.9xE-6 Torr. Leak detector base pressure:6.0xE-3 torr, base leak rate: 1.0xE-9 atm.cc/sec. Applied 80 psi helium to heat shield circuit for 5 mins . There is no response on leak detector. The heat shield circuit is leak tight.