GlueX Target Meeting, May 17, 2011
Tuesday, May 17, 2011
1:00 pm EST
JLab: CEBAF Center, Room F224/225
- Review minutes from previous meeting: all
- Target Work Reports: all
- MOU status: Mark
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Present: Hovanes Egiyan, Jim Fochtman, Mark Ito, Chris Keith, Tim Whitlatch
We went over the target requirements list that Tim prepared. The following items came up in discussion:
- Five hundred Gauss on the cold head is maximum according to the manufacturer. Is this OK?
- We want to be able to cool the target in one shift.
- The average diameter of the target is spec'ed at 2 cm. Is that OK?
- Length of target is 40 cm: can this be finalized?
- The maximum OD of the scattering chamber driven by start counter and that is driven in turn by the CDC.
- What is the alignment requirement for target?
- How well do we have to know the density of the liquid?
Additional requirements were raised in the discussion:
- specification of quality of scattering chamber vacuum (prevent freezing material on target)
- flammable gas compatibility of system
- interlock of nearby electrical systems and/or ignition sources if target cell ruptures
- hydrogen gas sensors will be needed
- pressure switch on vacuum chamber
- specify stainless steel tubing
- specify welding whenever possible
Tim showed the current drawing of the target, scattering chamber, and start counter area from Slava.
We looked over the two versions of a piping and instrumentation diagram for the target that Chris prepared
- Hydrogen and deuterium tanks outside connect to a single line going to the Hall.
- A vent line goes outside hall; a manual valve is provided.
- The vacuum pump needs an explosion-proof motor.
- In the second version, the gas panel is mounted outside hall so changing gas could be done without access to the Hall. It would still be manual operation.
- We could put gas panel and control electronics in the "target" rack.
- Electronics needed:
- temperature controller
- local visual read-back for pressure transducers would be nice to have
- turbo controller for scattering chamber
- vacuum gauge controller
- These designs allow automatic transition to cold gas in the target cell, but not to vacuum.
Next Area of Work
- The next step is to work on the mechanical design for target condenser, cell, scattering chamber.
- We may not want to have the cold head provide any mechanical support; copper braid could provide flexible thermal coupling.
- Jim will contact Chris to work out issues before the next meeting