Dear Peter, We also thought about the temperature problem and have an idea to stabilize a piece of copper. PURA Sensor, two cut-off valves for it, and about 70 cm of inlet tube will be fixed on this copper plate and stabilized by two peltier elements using spare DAC channel from our control block. Besides, we will measure and log temperatures of this copper plate and ambient. I attached our preliminary plans. FZJ means Forschungszentrum Juelich. BNL = Brookhaven National Lab. Two last rows contain our colleagues mainly involved in BNL and FZJ experiments (we have to consider their plans to arrange ours). Thanks for your congratulations. At least now I feel much better because I was worry about the previous control system, which was permanently modified during the building of the CHUPS. This is usual way, but I'm much happier, if there is time and money to draw and assembly everything in final version without "air wires" and things like that. BTW, I miss one important thing in the report. Now CHUPS could operate without computer. I had implemented all control loops including compressor cycles in the microcontroller, which is obviously more stable than PC. Best regards, Peter (on behalf of CHUPS team). Saturday, July 2, 2005, 6:39:27 PM, you wrote: > Dear Peter et al., > A few remarks to the mass flow controller. > Concerning the temp dependence I see the following plan > of action. > i) Try to stabilize the tent to a few degrees. That's what is done > in critical clean room applications which need a well defined > ultra low moisture level. We should log the temperature in our > slow control. > ii) Try to stabilize the sensor to a few degrees. According to the > company, it is not clear that this will help, because the > pipes and materials before the sensor will react to the change > in ambient temperature. But we could try. BTW are we using > electropolished pipes? > iii) There information article mentions several interesting facts. > Hydrogen is a bad purge gas for moisture, Alu is bad. > So we cannot expect a fast response of our system. > Conc the residual moisture of 75 ppb or so. > iv) If that is confirmed with our TPC in an extended measurement > in fall, it would clarify an important uncertainty in our > previous run. > v) The source of this moisture should be carefully studied. If it > is really the pipes, than we should consider a filter right > before the TPC entrance. > Overall, I am pleased with these initial tests. In the end stable > equilibrium conditions and patience will be required at this > sensitivity level. > Please email we your tentative plans, so that I can discuss them > with Alexei. > Congratulations again to your fine work. In the US one would say > "Mission achieved", because you accomplished all your plans. > Have a good trip home and best regards > Peter > On Fri, 1 Jul 2005, Peter Kravtsov wrote: >> Dear colleagues, >> >> I attached our updated status report with added >> moisture sensor experiments. >> We started to formulate working plans concerning CHUPS and >> PURA sensor and would be glad to receive >> comments/remarks/proposals. >> >> -- >> Best regards, >> CHUPS team. -- Best regards, Peter mailto:pkravt@gmail.com
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Autumn plans.xls
Description: MS-Excel spreadsheet