SLD Trip Report
The author visited the facility to gain an insight in the experience of the LAr filling of the SLD Barrel and North End Cap, and the cooldown of the South End Cap. Cryogenic commissioning began mid-September, 1989, and continued to Cooldown, January 3, 1990. Cryogenic commissioning followed the construction and installation of the piping. The checkout was serial and problems found 'as we were going along'. There was a clear message to work in parallel and certify subsystems in advance of their need. Typical problems were VJ line external bellows and ball valves that were not He leak tight. The early preparations concentrated on the relief (singular) of the LAr 100,000 I dewar (sound familiar?). About one month was lost to the refurbishing of valves. After commissioning the dewar they accepted four LAr transfers for a total of 15,000 gallons, each in the range of 0.4-0.6 ppm O{sub 2} measurement with equipment accurate to +/- 0.1 ppm. As I watched, tests were concluding that qualified the Barrel calorimeter as having LAr with 0.6 +/- 0.1 ppm O{sub 2} to the delight of those making the measurement. There was real satisfaction in the recent HV measurement that only 55 of 40,000 channels had shorts. The ratio is essentially that predicted from the early module testing experience and another reason to celebrate. Twelve of the twenty-four Barrel feedthroughs flanges (one end, total is forty-eight) had been fitted with Pre-Amps and that installation seemed to be going very well. There are hermetic feedthroughs at the PV wall, a length of manganin wire in the vacuum space to a warm hermetic feedthrough flange that is double 'O' ring sealed in the vacuum vessel closure plate. The Pre-Amps mount directly to the atmospheric side of these feedthrough flanges. The instrumentation is 'Bare Bones'. There was a need for flow meters when concerns for cooling loop flows arose and it would have been very helpful to be able to measure the flow in the Argon fill lines. The inside-the-LAC vessel instrumentation (RTD's and TC's) was sparse and had no redundancy. They would have provided more instrumentation and/or redundancy knowing what they know now. I asked questions designed to determine the time and effort necessary to pump the cryostat free of, especially, water. There didn't seem to be a clear answer to the question with the explanation that there was lots of pumping in support of the leak checking and the water was pumped along the way. I take that to mean that water was not a particular problem or a deterrent to the leak checking.
- Research Organization:
- Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC)
- DOE Contract Number:
- AC02-07CH11359
- OSTI ID:
- 1031846
- Report Number(s):
- FERMILAB-D0-EN-248; TRN: US201201%%1035
- Country of Publication:
- United States
- Language:
- English
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