[Halld-jlab] Hall D Staff meeting notes, May 6, 2013

[Mark M. Ito]

Find the notes at 
https://halldweb1.jlab.org/wiki/index.php/Private:Hall_D_Staff_Meeting,_May_6,_2013 
and below.
   _____

Private:Hall D Staff Meeting, May 6, 2013

    Present: Fernando Barbosa, Eugene Chudakov (chair), Mark Ito, David
    Lawrence, Bert Manzlak, Lubomir Pentchev, Elton Smith, Simon Taylor,
    Tim Whitlatch, Glenn Young, Beni Zihlmann

Eugene, Magnet Report

      * current was measured at 1300 A
      * central line matched with scaling of 1500-A map to better than a
        few percent
      * during ramping to 1500 A, magnet quenched
           + helium dumped
           + rupture disk broken
      * magnet designed to stand full quench with all power going into
        magnet
           + there is a 20-to-1 ratio of copper to superconductor
      * quench started in sub-coil 1 of coil 1 moved initially to coil 4
           + temperature went up by 30 K
           + can measure resistance and infer temperature
      * no indication of overheating inside magnet
           + most of energy went to magnet, very little in dump resister
           + about 4 times more resistance in dump resister
      * everything went normal, perhaps with exception of one sub-coil
      * pressure could cause leaks, but no indications of that so far
      * vacuum problems seen, but known from before, there was a plan to
        fix anyway
      * temperature of He depends on pressure, pressure was too high,
        crossed critical current
      * coil resistance looks nominal
      * magnet has never has a quench before, this was a first
      * quenches have been captured before
      * If cryo plant shuts down, pressure increases at full current, ramp
        down speed may not be fast enough to keep magnet sub-critical
           + perhaps add pressure relief chamber
      * current cryo plant is weak
      * plans are still developing
      * root cause: possibly coil moved
           + on the other hand no voltage spike in record, and resistance
             rose in two seconds then took off
      * path forward
          1. restore cryoplant, clean out carbon
                o magnet could be full in two weeks
          2. low current test with magnet cold
                o requires review and TOSP
          3. then warm up, work on cryoplant, prepare for full power test
      * definition of full current may have to be adjusted
      * quench detector needs to be changed to allow lower threshold
      * more interlocks on pressure system will have to be installed
      * Claus assumes that no re-baselining will be approved until magnet
        fully tested
      * magnet now at 30 K, perhaps 40 K, will be kept below 80 K
      * physics and 12 GeV will jointly conduct over post-incident
        investigation
      * TOSP goals will have to be developed
      * there were no personnel safety issues associated with the quench

Bert, Safety

      * in conjunction with Lehman review, CDC will have two people doing
        electrical safety review tomorrow
           + interviewees have been notified
           + will look at Hall A, experimental review process
                o how we bring in electrical equipment from outside Lab

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-- 
Mark M. Ito, Jefferson Lab, marki at jlab.org, (757)269-5295