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On 1/26/2012 9:27 AM, Matt Poelker wrote:
<blockquote cite="mid:4F2162CC.8080800@jlab.org" type="cite">
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During the long shutdown, John Hansknecht will try to implement an
idea
that will allow us to produce longer laser pulses, which as Mike T
points out, could improve transmission, reduce prebuncher
gradient, and
eliminate tails, etc.,. Unfortunately, a longer laser pulse will
not
be available during QWeak and the rest of the 6GeV run.<br>
Matt<br>
<br>
<br>
Todd Satogata wrote:
<blockquote cite="mid4F202145.4060209@jlab.org" type="cite">
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<title>BTeam-2012-01-24</title>
Bteamers,<br>
<br>
Here are the notes from yesterday's weekly meeting. There was a
lot of
discussion about the<br>
tune time on Thursday that attempted to install a new M56 optics
in the
injection chicane<br>
but eventually was removed. Some issues were found in the model
that
will be addressed,<br>
a LEMI configuration problem was fixed, some optics anomalies
(such as
the<br>
disappearing/reappearing blown dispersion mismatch out of arc 2)
need
understanding.<br>
We learned important things during that tune time, but we will
be more
efficient if we<br>
have more time to plan and double-check for tuning; Yves's
summary at
the end of what<br>
worked and what didn't will be helpful for the planning of the
5-pass
spin-up; a plan is<br>
being developed that will be discussed and hopefully scheduled
by this
week's beam<br>
studies scheduling meeting on Friday.<br>
<br>
Alex Bogacz has graciously agreed to chair the BTeam meeting
while I'm
on travel<br>
to SLAC Jan 26-Feb 1 inclusive.<br>
<br>
-Todd<br>
<h1 class="title">BTeam-2012-01-24</h1>
<div class="outline-2">
<h2 id="sec-1">1 Optics on Call Report/Schedule</h2>
<ul>
<li>Rotates at BTeam (10:00 Tuesdays)<br>
</li>
<li>Medium-term machine development<br>
<ul>
<li><span class="done">DONE</span> Write 5-pass spin-up
ATLis
(Jay, <a moz-do-not-send="true"
href="https://cebaf.jlab.org/atlis/task/11894">a11894</a>),
relies
on ARC9 box supply repair (ongoing)<br>
</li>
</ul>
</li>
<li>17 Jan-24 Jan: Vasily/Yves (Outgoing)<br>
<ul>
<li>SL has still been running few degrees off crest to
reduce
Compton backgrounds (Jay)<br>
</li>
<li>Hall B sensitivity to energy drift of some concern
(Tief)<br>
</li>
<li>Mon 23 Jan Add M56 optics in injector (Yves/Jay, <a
moz-do-not-send="true"
href="https://cebaf.jlab.org/atlis/task/11924">a11924</a>)<br>
<ul>
<li>Not successful, see Yves's entry at <a
moz-do-not-send="true"
href="https://cebaf.jlab.org/elog/entry/1661381">e1661381</a><br>
</li>
<li>HGAP for inj chicane dipoles will be updated;
0L/0R
optics plan in the works<br>
</li>
<li>12h of tuning time: what was gained? How are we
accountable for that time?<br>
<ul>
<li>Who owns the process of unscheduled tuning?
Optics
or plan owner should be focus; PD schedules
time<br>
</li>
<li>Scheduling for studies <1h later makes
things
rushed, perhaps hours of inefficiency<br>
</li>
<li>OptiM to elegant translation can use better
efficiency (at least yesterday)<br>
</li>
<li>High sensitivity of Compton halo to 1L02
quad was
found at end in current configuration<br>
</li>
<li>Now running 2.5 degrees off crest in SL,
better
than the 6+ degrees over weekend<br>
</li>
<li>We're very likely on the edge of something,
including scraping, based on large
sensitivities<br>
</li>
<li>RayTrace would provide optics, may also well
provide an aperture check (Tief)<br>
</li>
<li>Spot was a lot tighter in 1A with the M56
improvement, so we will likely want to use
this in Feb<br>
</li>
<li>Is a longer laser pulse feasible for 180uA
for
better injector transmission/Hall B? (Tief)<br>
</li>
<li>Alex: Can redesign an M56 optics with a
stronger
1L02 quad setting for potentially improved
stability<br>
</li>
<li>Underlying cause of arc2 dispersion match
blown?
Was seen in previous week as well
(Jay/Spata/Tief)<br>
</li>
<li><span class="done">DONE</span> Jay has
changed LEM
config file for NL to set 1L02 quad to 521.6
(as of AM Jan 24 2012)<br>
</li>
<li><span class="todo">TODO</span> injector
rematch
with HGAP in 0R dipoles (Michele/Yves, report
Feb 02 BTeam)<br>
</li>
<li><span class="todo">TODO</span> Address blown
arc2
dispersion match during Jan 25 beam studies
recovery (Optics)<br>
</li>
<li><span class="todo">TODO</span> Planning
group for
M56: Yves/Jay/Tief/Alicia/Alex/Ed/Geoff/Yuhong<br>
</li>
</ul>
</li>
</ul>
</li>
</ul>
</li>
<li>24 Jan-31 Jan: Ed/Alex (Oncoming)<br>
<ul>
<li><span class="todo">TODO</span> Readdress injection
matching
to NL, SL gang phase, Hall C Compton<br>
</li>
<li><span class="todo">TODO</span> Restore SL MOMOD
after SL on
crest, confirm good Hall C Compton rates (Tief/ops)<br>
</li>
<li><span class="todo">TODO</span> Diagnose intermittent
problems in NL MOMOD (Musson? Tief? Plawski?)<br>
</li>
</ul>
</li>
<li>31 Jan-07 Feb: Yuhong/Geoff<br>
<ul>
<li>5-pass spin-up schedule? Mid-February for Hall A,
but early
Feb for Hall B shift?<br>
</li>
</ul>
</li>
<li>07 Feb-14 Feb: Balsa/Todd<br>
</li>
<li>14 Feb-21 Feb: Fanglei/Mike Spata<br>
</li>
<li>21 Feb-28 Feb: Todd/Jay<br>
</li>
</ul>
</div>
<div class="outline-2">
<h2 id="sec-2">2 Measuring Bunch Length using 1A Sync Light
Monitor
(Tief)</h2>
<ul>
<li>New BTeam elog entry on this procedure: <a
moz-do-not-send="true"
href="https://cebaf.jlab.org/elog/entry/1661304">e1661304</a><br>
</li>
<li>Done capturing images from datacube; online bunch length
application may be resurrected (Michele/Tief)<br>
</li>
<li>Arne believes this will be resurrected when we have pure
digital cameras for 12 GeV<br>
</li>
<li><span class="todo">TODO</span> Prioritize and projectize
for
long down (Arne)<br>
</li>
</ul>
</div>
<div class="outline-2">
<h2 id="sec-3">3 C100 Status</h2>
<ul>
<li>26/52/79 Hz signal on 1/4 cryo drive gradient/phase
(Suleiman/Spata)<br>
</li>
<li>Beam studies rescheduled for Wed 25 Feb<br>
</li>
</ul>
</div>
<div class="outline-2">
<h2 id="sec-4">4 Beam Studies Report 18 Jan 2012</h2>
<ul>
<li>Studies scheduled 08:00-20:00 (on time)<br>
<ul>
<li> <a moz-do-not-send="true"
href="https://cebaf.jlab.org/atlis/task/11858">a11858</a>
0.0 C100: Search for 79 Hz (Parisitic, Suleiman/Spata;
strong 52 Hz on
1/4 cryo drive gradient/phase) </li>
<li> No other studies accomplished due to box supply
failures,
repair </li>
</ul>
</li>
</ul>
</div>
<div class="outline-2">
<h2 id="sec-5">5 Beam Studies Scheduled 25 Jan 2012</h2>
<ul>
<li><span class="todo">TODO</span> Submit ATLis items for
desired
beam studies for next week (25 Jan)<br>
</li>
<li>Same studies as last week based on lost time to box
supply
failures<br>
</li>
<li>Studies scheduled 08:30-20:30<br>
<ul>
<li> <b>[<span style="visibility: hidden;">X</span>]</b>
——
1.0 Optics: Fopts/allsaves </li>
<li> <b>[<span style="visibility: hidden;">X</span>]</b>
<a moz-do-not-send="true"
href="https://cebaf.jlab.org/atlis/task/11882">a11882</a>
8.0 C100:
Stability testing (Hovater, Spata, etc, full gradient
on both C100s,
10uA) </li>
<li> <b>[<span style="visibility: hidden;">X</span>]</b>
<a moz-do-not-send="true"
href="https://cebaf.jlab.org/atlis/task/11865">a11865</a>
1.0
Modeling: RayTrace validation (Bodenstein, Tief) </li>
<li> <b>[<span style="visibility: hidden;">X</span>]</b>
<a moz-do-not-send="true"
href="https://cebaf.jlab.org/atlis/task/11885">a11885</a>
0.0 PePPo:
Modeling (Grames, Contingency) </li>
<li> <b>[<span style="visibility: hidden;">X</span>]</b>
<a moz-do-not-send="true"
href="https://cebaf.jlab.org/atlis/task/11849">a11849</a>
0.0 Mott:
Mott DAQ Test (Suleiman, Contingency) </li>
<li> <b>[<span style="visibility: hidden;">X</span>]</b>
——
2.0 Optics: Restoration </li>
</ul>
</li>
<li><span class="todo">TODO</span> Optics should write
notes,
observations of fopt/etc to Bteam elog<br>
<ul>
<li>Include pathlength check (pathlength was good Mon
day)<br>
</li>
</ul>
</li>
</ul>
</div>
<div class="outline-2">
<h2 id="sec-6">6 Next week</h2>
<ul>
<li>Alex Bogacz has graciously agreed to chair while Todd is
on
travel<br>
</li>
<li>Hall B to 5th pass ~ Feb 1?<br>
</li>
</ul>
</div>
<div class="outline-2">
<h2 id="sec-7">7 From last week: Evaluate possibilities of
Krest
during beam restoration (Okay)</h2>
<ul>
<li>Takes more like 4h to run through both linacs to get
decent
results (Terry)<br>
</li>
<li>But Hall C doesn't get good data while Krest is running
either
(but Hall B can)<br>
</li>
<li>Perhaps part of 2h can be a manual touch-up of cresting
(15 min
total, 2 operators)<br>
<ul>
<li><span class="todo">TODO</span> Todd has emailed Noel
to see
if manual touch-up is acceptable weekly retune</li>
</ul>
</li>
</ul>
</div>
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</blockquote>
<br>
<br>
<pre class="moz-signature" cols="72">--
Matt Poelker
Jefferson Lab
MS Bldg 5A, Rm 500-17
12000 Jefferson Ave.,
Newport News, VA 23606
<a moz-do-not-send="true" class="moz-txt-link-abbreviated" href="mailto:poelker@jlab.org">poelker@jlab.org</a>
757-269-7357 office
757-897-9408 cell
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</blockquote>
Not that I want to stop progress, but I would point out that<br>
we are not scheduled to do any 180 muA running to any hall<br>
AFTER the shutdown, and even if we were, my calculations<br>
show that at 500 MHz and 180 muA, the beam charge is<br>
0.36 pC. If some form of "space charge" mechanism is being<br>
invoked that might "get better" with less charge density, I would<br>
need to see a calculation using, e.g., a formula from Rieser to<br>
convince me that <br>
<br>
What IS certain is that the larger bunch length will introduce<br>
greater curvature effects in the compression and aberations.<br>
Not a clear improvement to me!<br>
<br>
Geoff<br>
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