Minutes of meeting held on 30 Jul 2020
==========================

slides are at:
https://beamdocs.fnal.gov/AD-private/DocDB/ShowDocument?docid=8609

(1) Robyn gave an update on the wide bore cavity high power test.
    (i) The wide bore frequency is too low at high bias. Frequency was
    too low. Modified to 3500 A. Really pushing the bias supply.
    (ii) Cavity test used 15 Hz.
    (iii) Tests were performed over 5 separate days.
    (iv) Goal is 60 kV which means 27 kV of modulator voltage.
    	 (a) Cavity gap voltage can be calculated with stepup
         ratio. Stepup ratio was calculated and confirmed by
         meaurement.
   (v) Tuner configuration uses 2 species of ferrites.
   (vi) To get to 53 MHz, 3500A is required bias.
   (vii) Day 1: tripping due to sparking. Modulator at 26 kV.
   	 (a) ran at 25 kV to condition.
   (viii)  Day 2: Able to run modulator at at 27 kV for 10 min without sparking.
   (ix)   Day 3: mod = 27 kV, still sparking. Sparks may trip the bias
    supply. Most sparks are not latching on safety system, comes back
    a few seconds later. Sparks cause vacuum activity.
   (x) Day 4: Took off PA. Discovered:
       (a) Screws sticking into RF volume.
       (b) Front tuner was not flush with ID of stem.
       (c)  Screws on RF choke capacitors not fully tightened.
       (d) Tuner stem screw heads have sharp edges. Fix requires
       dismantling.
       (e)  Put cavity back together after fixing what can be
    fixed. Ran at 26 kV with no sparking. 27 kV sparking.
       (f) Can hear snapping sounds outside the cave.
   (xi) Day 5: Ran again at 27 kV. Entered cave to locate sparks.
       (a) Radiation level higher at upstream near gap (smart ion).
       (b) Couldn't locate sparks coming from tuner stems.
       (c) Listening and looking couldn't locate it. Very likely, that
       the problem is in the vacuum part of the cavity.
	(d) Interesting that sparking occurred randomly. Each one is
	always followed by vacuum event.
       (e) Opening up to look (John is very confident that it is
    upstream end).
  (xi)  Plans::
  	(a) Cavity is being taken apart. Efrain is making a fixture
  	for stretched wire measurement.
	(b) Upstream gap will be examined.
	(c) Tuners will be taken off after wire measurement.
	(d) Tuners will be modified to get it in frequency range.
	(e) Plan is to complete low and high power tests and install
        before Xmas.  put in before Xmas.
   
(2) Valery gave a talk above the taller D magnets for extraction
   (i) He first gave some background information.
       (a) Extraction is at L3. Extraction trajectory > 2.5 deg. To
       keep symmetry, both upstream and downstream D magnets will be
       the same.
   (ii)   From previous work:
     (a) Vertical position of circulating beam before extraction
   y=0. Sims suggest significant losses at upstream F magnet.
     (b)  Requirements for new D magnet derived from MADX sims.
  (iii)   Recent work:
    (a) Experiments were done to look at BPM data at around
    septa. Bumping the beam vertically to see the losses. 100 turns
    before extraction. Comparison with BPM data and simulated
    trajectory values do not agree. Tried tuning but get strange
    trajectories.
    (b) One culprit is BPM LU3. It was repaired but even after repair
   LU3 position still  does not match simulations.
   (c) Finally got similar to BPM data using 02March2020 (but still
   not at LU3) data. Calibrated kick angle around Booster. Not suitable for global
   matching.  Could provide guess values for local matching in
   restricted area.
(iv) Trajectory is probably -9 mm at septum. It is better to use
   corrector package currents instead of measured BPM values.
(v) Results:
   (a) D magnet still require +5 mm 1/2 gap increase (10 mm full gap)
   (b) New calculations show beam does not hit F magnet. D magnet is
   most serious problem. Valery is confident of these results.
   (c) Dave suggests moving BLMs to measure losses at the F and D
   magnets to be sure.
   (d) Salah says that BLMs can 025 is on top beam pipp and can be put
   in between F and D.
   (e) During upcoming studies period we should do this experiment.