Difference between revisions of "Minutes-2-23-2012"
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- First cell of the third package was assembled yesterday, flushed with gas over night and today we were able to apply HV which by now is already the nominal one. The dark currents are very low. If it holds over the night we will assume that the wire deadening procedure works and we will continue tomorrow with the deadening of the next wire plane. Tomorrow also we will test the first cell and if everything is OK will try to assemble the second cell so that we can use the weekend to flush it. | - First cell of the third package was assembled yesterday, flushed with gas over night and today we were able to apply HV which by now is already the nominal one. The dark currents are very low. If it holds over the night we will assume that the wire deadening procedure works and we will continue tomorrow with the deadening of the next wire plane. Tomorrow also we will test the first cell and if everything is OK will try to assemble the second cell so that we can use the weekend to flush it. | ||
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== First package testing == | == First package testing == | ||
| − | - Beni showed results posted in the new FDC Elog linked above, | + | - Beni showed results posted in the new FDC Elog linked above. After all the gas problems have been fixed/identified, now the main concern is the chamber efficiency. The only time we had full efficiency was in cell#3 when it was leaking through the hole in the exhaust tube and was taking most of the gas flaw, but not clear what fraction of the total 200ccpm at that time. There are also two groups of 4 channels not working, but the problem is not in the chamber; Beni will investigate it. |
| − | - | + | - Obviously this is a gas problem and we discussed different ways to approach it. Beni: wanted to install the two new mass flow controllers that allow to have 500ccpm each, but before that we will install the oxygen sensor. Lubomir: we have to make sure there are no air bubbles between the cathode and ground planes; for that we will incline the package so that the supply is at the lowest and the exhaust at the highest point. |
== Engineering == | == Engineering == | ||
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| + | <!-- | ||
- Bill discussed with Beni the gas system already before the meeting. With the present MKS we can't have flows higher than 280-300 ccpm and we may need higher flows to improve the chamber efficiency. Bill will start designing the new gas system. At present Beni has two mass flow controllers with 500 ccpm max flow (for nitrogen) capable of supplying in total >700 ccpm Ar/CO2. | - Bill discussed with Beni the gas system already before the meeting. With the present MKS we can't have flows higher than 280-300 ccpm and we may need higher flows to improve the chamber efficiency. Bill will start designing the new gas system. At present Beni has two mass flow controllers with 500 ccpm max flow (for nitrogen) capable of supplying in total >700 ccpm Ar/CO2. | ||
Revision as of 19:52, 23 February 2012
February 23, 2012 FDC meeting
Agenda
- Production Construction Tracking (Dave)
- Production status
- Testing at Blue Crab (Lubomir)
- First package tests FDC ELOG (Beni, Lubomir)
- Engineering update[1],cooling manifold (Bill)
- Electronics update (Nick)
- Other
Minutes
Participants: Bill, Dave, Nick, Elton, Mark, Simon, Beni, and Lubomir.
Production
- Dave: Deadened the first wire plane of package 3 with the larger diameter using the procedure with increased current and the same time as for the smaller diameter, but adding extra polishing cycle. Working on four cathodes now and on the last wire frame for the third package. One more cathode to finish the package. There's not much space to start the fourth package. Testing the chambers of the third package will be the bottleneck since it takes time to flush the chambers with gas. We will try to use weekends for that if possible. Third package was started partially end of November, so less than three months ago. Still we need to work on the subsystems for both package 2 and 3.
- First cell of the third package was assembled yesterday, flushed with gas over night and today we were able to apply HV which by now is already the nominal one. The dark currents are very low. If it holds over the night we will assume that the wire deadening procedure works and we will continue tomorrow with the deadening of the next wire plane. Tomorrow also we will test the first cell and if everything is OK will try to assemble the second cell so that we can use the weekend to flush it.
First package testing
- Beni showed results posted in the new FDC Elog linked above. After all the gas problems have been fixed/identified, now the main concern is the chamber efficiency. The only time we had full efficiency was in cell#3 when it was leaking through the hole in the exhaust tube and was taking most of the gas flaw, but not clear what fraction of the total 200ccpm at that time. There are also two groups of 4 channels not working, but the problem is not in the chamber; Beni will investigate it.
- Obviously this is a gas problem and we discussed different ways to approach it. Beni: wanted to install the two new mass flow controllers that allow to have 500ccpm each, but before that we will install the oxygen sensor. Lubomir: we have to make sure there are no air bubbles between the cathode and ground planes; for that we will incline the package so that the supply is at the lowest and the exhaust at the highest point.
![[1]](http://www.jlab.org/Hall-D/detector/fdc/drawings/NEW_MANIFOLD_ASSY2.png){kind=link}
