Difference: Vacuum (7 vs. 8)

Revision 82008-06-05 - EddyJans

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META TOPICPARENT name="VELOOperatingManuals"

Operating the VELO Vacuum System while being under a neon atmosphere

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  • If -4.8 < DP < -4.0 mbar, you are lucky and can continue with "Cooling operating under neon". If not, you first have to create a good starting condition, i.e. a good differential pressure. This can be done by moving the detector halves. To do so you have to perform the following actions on platform C3.
  • The actual value of DP can also be read off the Vacuum main page on the PLC-screen in rack C3B05.
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vac_main.bmp
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  • bypass the vacuum interlock that prevents moving the detectors. So push the following marked buttons on the PLC screen. If you happen to be on a different page first press the "Home"-button (bottom-left) or "Vacuum control"-button to get there.
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  • Go to screen of "MotionControl-3" and check that the PLC is not "hanging in a procedure". If so, one or more blocks on this page will be green and you have to push the button "Reset Procedures". Once all blocks are grey you can continue with the next step.
 
  • Pull out the red mushroom button on the motion system in motion rack C3B03 at 1m20 from the floor.
  • now the 4 lights that are encircled in the following figure should be green, indicating that you can move the VELO-detectors.
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  • go to the "motion control" screen (see following figure). Beware of the fact that a higher value for both X-LEFT and X-RIGHT corresponds to more to the outside !! Move alternatingly the VELO-
halves outwards in steps of 0.5 or 1.0 mm. Always keep a spacing of at least 1.0 mm between the boxes, i.e., |XL + XR| >= 1.0 mm. (At AP=850 mbar moving 1 mm outwards corresponds to an increase of DP of 0.6 mbar.) Wait after every step until the pressures, as represented by AP411 and DP411, are stabilized. To move a detector half, touch the corresponding setpoint, type a new value, type return, make sure you did the right thing, press the "MOVE HORIZONTALLY (X)" button and watch carefully what happens with: position, potmeter readings, DP411, PV301 ... 306 (which should stay closed, which means red).
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  • go to the "motion control" screen (see following figure). Beware of the fact that a higher value for both X-LEFT and X-RIGHT corresponds to more to the outside !! Move alternatingly the VELO-halves outwards in steps of 0.5 or 1.0 mm. Always keep a spacing of at least 1.0 mm between the boxes, i.e., |XL + XR| >= 1.0 mm. (At AP=850 mbar moving 1 mm outwards corresponds to an increase of DP of 0.6 mbar.) Wait after every step until the pressures, as represented by AP411 and DP411, are stabilized. To move a detector half, touch the corresponding setpoint, type a new value, type return, make sure you did the right thing, press the "MOVE HORIZONTALLY (X)" button and watch carefully what happens with: position, potmeter readings, DP411, PV301 ... 306 (which should stay closed, which means red).
 
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  • When DP has reached a value between -4.8 and -4.0 mbar this part of your mission has been completed successfully. Now press the red mushroom button on the motion system in motion rack C3B03 (to inhibit movement of the detectors) and remove the bypass on (in other words reactivate) "inhibit to motion".
 
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