Minutes of meeting held on 11 Feb 2021
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Link to slides: https://beamdocs.fnal.gov/AD-public/DocDB/ShowDocument?docid=8974

(a) Tan gave an update of work done in Booster
    (1) Klystron testing coninues. Test stand has intermittent
    problems but klystron has been tested to 9 MW. Goal is 10 MW.
    (2) Adiabatic capture experiments were done during the adhoc
    studies period by Chandra.
    (3) RF phase data analysis continues. We now have a much better
    understanding of what the LLRF+HLRF is doing during paraphasing.
    (4) 2nd harmonic. Drafter from TD has been assigned to do
    drawings. Parts picked up for cleaning. Deciding between wire or
    foil braze material.
    (5) Wide bore. Replacing ferrite in tuners. Start welding this
    week.
    (6) E4R. E4R test stand install continues. Repair of bus
    bars. Goal is to start testing in summer.
    (7) Dampers. Bill's mode 2 dampers work well. Definitely needed
    for > 14 turns. Power being measured right now for PIPII review.
    (8) LLRF. Work continues. Hardware being built.
    (9) New CHG0. Waiting for PIPII CD3A approval. Review next
    week. Expect approval in mid March. PO's in May. Goal to install
    during shutdown.

(b) Kiyomi gave a talk about the MTA spark investigation
    (1) When MTA started operating, BLMs indicated high losses at the
    start of the HE part of Linac.
    (2) Transmission efficiency to MTA < 60%
    (3) Horz orbit was unstable.
    (4) BLM noise traced to ramping C-magnet. The BLM noise appeared
    even without beam.
    	 (a) The noise was mitigated by adding common mode chokes to
    filter it out.
    (5) Historical data from Jim Crisp showed that 800A p-p current
    appeared on the beam pipe when C-magnet pulsed.
    (6) 800 A p-p was confirmed with measurements.
    (7) Rogowski coil measurements indicated sparking in MTA
    (8) At this point, MTA ops was stopped to investigate the source
    of the sparking.
    (9) 2 CT's and 3 Rogowski coils were placed at different locations
    on the beam pipe to bracket the location of the sparks.
       (a) Bracketting eventually showed that the source of the spark
    was in the long C-magnet.
       (b) The Rogowski coil would show opposite
    slopes depending whether it is upstream or downstream of the spark location.
    (10) The source of the spark was found to be the beam pipe
    touching the long C-mag pole face. (spotted by Salah)
    (11) A G-10 card was used to isolate the C-mag pole face from the
    beam pipe.
    (12) After the fix, the sparking stopped.
    (13) There was a controls problem with triggering that caused a
    timing jitter between the C-mag pulse and beam.
    	   (a) This jitter causes beam orbit to move.
	   (b) After fix, beam to MTA is 97% efficient.
	   (c) Orbit became stable after fix.
    (14) Plans are
    	 (a) increase pulse length to MTA from 35 us to 50 us.
	 (b) BLM noise reduction with more chokes, trace BLM cables to
    find ground loops and take the opportunity to do BLM calibrations.
         (c) New TLG to increase number of MTA events.
	 (d) Replace beam pipe under C-magnet with PEEK or cerama or
    make ceramic gaps to reduce/remove the induced current.

(c) Jeff gave the ecloud in Booster talk
    (1) Observed linear emittance growth that is charge dependent.
    (2) Early in the cycle emittance growth is dominated by space
    charge. Non-exponential dependence on intensity.
    (3) Later in the cycle, with high intensity, the growth is very
    rapid as intensity is increased. Is this from ecloud or from other
    ramp effects?
    (4) Ecloud can be trapped in gradient dipoles. Demonstrated in
    Recycler.
    (5) Booster notch length is changed by using the laser notcher and
    the Booster notcher. A double notch is formed for the +6 laser
    notch after the kicker notch.
    	(a) Laser notch at +6, +4, +3, 0, -3 buckets after the kicker
    notch was used.
    (6) Emittances were measured using the 8GeV multiwires.
    (7) Statistical analysis show that although the reduction in
    emittance for the +6 case was only 0.4 pi mm mrad w.r.t. nominal
    (2% reduction), it is significant change.
    	(a) +3, and +4 cases is suggestive at the 2 to 4 sigma level.
    (8) Double notch (+6) not recommended to be used for current operations
    because the emittance reduction washes out when the current is
    increased to compensate for the notch.
    (9) For PIPII, simulations need to be done whether double notching
    will remove ecloud or just partially mitigate it.
    	 (a) Additional ramp-dependent effects have to be taken into
    account.
    (10) RF measurements to "see" ecloud in the dipoles would be an
    interesting project.
    	(a) Laminations of Booster magnets may present a poor RF
    transmission environment.
    (11) Some points to consider:
    	 (a) Vary intensity to see whether the bunch pattern effect is
    seen. Might rule out ecloud if seen at low intensity.
         (b) IPM averaging. Can it be used to see the head and tail of
    train? Head should have least growth while tail should see the
    highest.
        (c) When an RF cavity is changed out, a large sector is let
    up. Might be able to see an effect.