target update

[Silviu Covrig <silviu@krl.caltech.edu>]

Hi,

I did a few checks in the last days related to the target system, before 
the hall closes (it supposed to happen today, sometime).

1. target motion, the motion software is designed, it has buttons, five, 
for five target positions: in beam, out of beam, small hallo, big hallo 
and C target. Each button can be enabled or disabled by a separate button 
and there is also a logical sequencer that has a different enable/disable 
button that has to be enabled in order to be able to move the target. 
Please take a look at the attachment. There is a problem with this. The 
readback from the target motion control box is noisy. The box itself 
reads back the target position to +/- 2 mV (1 mV is 11 microns), but the 
signal that is read by the software from the box has a 50 times higher 
noise, so by the time the signal gets into the computer the position is 
diplayed with fluctuation of +/- 100 mV or higher than +/- 1 mm. The noise 
seems to come either from the Maryland breakout boxes or from a grounding 
problem. Also, because of this noise an actual target position cannot be 
reached from the computer to better than 0.5 mm. We didn't have time to 
address the noise problem prior to the hall's closing, but will work on it 
in September. The same kind of noise was seen during the LH2 tests on the 
high power heater readback from the power supply into the daq.

2. the pump controller is in the racks in the hall. I checked the pump, 
just to see that it still turns and it does. At 50 Hz, as expected, we 
didn't see the direction of rotation on the gas panel.

3. I ran some tests on the gas panel to see if there is a leak after the 
R11 and RD1 replacements. There seems to be none on the H2 circuit and we 
found one small and slow on the Helium circuit. The major test was to 
pressurize the loop with house Helium to 12 psig and close the supply, 
separate the cells by closing MV9, raising the He-cell supply to ~20 psig 
and closing MV11. The system left like that overnight didn't lose pressure 
on the H2 circuit, but the He bottle for the He circuit lost 200 psig. So, 
the Sample R11 does the same job like the previous R11, bleeds 
continously, and doesn't seem to be a leak in the H2 circuit. The pressure 
right now is slightly possitive with the cells in connection and the 
supply closed (Mike Seely doesn't want to waste house Helium).

Silviu

targetmotion.ps