Wire Scanner and Collimator Meeting Minutes, April 18, 2006

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Contents

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Attendees:

Agenda:

1. Review motion hardware status
2. Collimator update
3. BC1 motion update
4. Review Software status
5. Detector topics, including some answers to last meeting's questions

Previous Actions: (summary; see details below)

1. Doug will determine the required high voltages, and if remote control is required.
2. Doug will determine the specifics of the gas mixture for the ion chambers.
3. Doug will determine if standard PMT bases can be used.

New Actions: (summary; see details below)

1. Doug will determine if BC1 motion readback can be isolated to specific positions.

(See response below.)

Minutes:

1. We reviewed the status of Motion control Hardware
   1. James will make up cables to all the SMDS4 to be driven from a Joerger SMC-24BP CAMAC module.
   2. He hopes to have it complete this week, to allow more rigorous testing of the SMDS4, until the EPICS software is ready.
   3. James is also finishing some work at End Station A.
   4. Doug was asked about the status of the Naming scheme, and said there are currently names assigned to the Wire Scanners and Collimator for the injection area, up to the end of Sector 21. The PMTs and Ion Chambers are not yet named.
   5. Tom said the decision on which type of drive mode to use has been made. Motor control for all Wire Scanners, Collimators and related motion will be based on a Unipolar drive (L/R mode) of operation.
   6. James mentioned that the LAMBDA power supplies being used for our current motion control tests supply digital and analog outputs for readback and status. It's not clear if we'll need to use them.
2. We discussed the Collimator at BC1 in Sector 21.
   1. Rene said the PDR scheduled for this week was postponed because of the FAC Meeting. Tim said it might happen next Tuesday (April 25), and will let us know.
   2. Tom asked if the motor details on the collimator have been decided. Rene said yes, but the torque details are not yet available. There was discussion about several motors ranging from 100 oz. inches up to 150 or 200. The MO62 and MO91 motors were specifically mentioned. Rene will calculate the required torque and communicate that to Tom and James.
   3. Tom also mentioned that he's talking with Danaher about motor specifics, and a good variety of motors are available to us. He's currently discussing the motor wiring for radiation environments.
   4. Tim said that requests for quotes are out to build the collimator jaws. The BC1 collimators are the priority because of long lead procurements.
   5. He suggested that we might have a physically assembly on which to mount a motor sometime around mid July.
   6. It was mentioned that the BC1 drive would probably have an MO62 motor with 5:1 reduction.
      1. We again speculated as to whether we need fine position resolution across the entire 11 inches of beamline travel. Doug will speak with Paul or Patrick to find out. ^ Action: Doug will determine if BC1 motion readback can be isolated to specific positions. ^ ^ Response: Doug spoke with Paul after the meeting, and found that the total travel distance is actually 30 cm, but a range of required accuracy for readback is between 14 and 30 cm. We will still need to know when the beamline is at 0, but we do need 16 cm of fine resolution (250µm.) ^
      2. Tom asked if it would be possible to use both a coarse and fine LVDT for measuring the travel of the BC1 beamline. Although we would use 2 LVDT channels, it would provide much better feedback.
3. Doug spoke about the status of the motion control software.
   1. He is currently 3 - 4 weeks behind the current schedule.
   2. Currently working on fixing problems with the software drivers for the carrier card and motor controller card.
4. We then discussed the wire scanner detectors.
   1. We discussed the actions from last meeting. Doug went over the list, based on e-mail from Doug McCormick.
      1. Determine if remote control is required.
         1. No, assuming beam conditions, spot size, beam current or backgrounds do not change often, and do so by small amounts.
      2. Determine the high voltages that we need.
         1. For PMTs, 0 to 3kV will handle everything, and 0 to 2kV will support 99% of what we'll need. Typically, we need 0.5 to 1.0 mA per tube.
         2. Ion chambers require less, typically under 1kV.
      3. Determine the specifics of the gas mixture for the ion chambers.
         1. We will typically use the standard mixtures used in the PLIC, which is 95% Argon and 5% CO2 Narrower pulse output can be achieved with 90% Argon and 10% CF4 (Carbon Tetrafluoride)
      4. Determine if standard PMT bases can be used.
         1. Some investigation is required, since the bases can produce non-linear signals, which can affect the resulting sigma calculation. Philips XP2012b tubes have typically been used in the past, and the mix of those with a detuned base gave linear results. There is a question as to whether we can compensate for these non-linearities in software.
   2. James suggested that existing HV power supplies might be available from the FFTB, currently being dismantled. He said they can each typically drive 4 or 8 channels.
      1. There was a question about whether they can be validated under our NRTL mechanism.
      2. James and Tom are both qualified to provide NRTL validation.