[Bteam] injector relative orbit and zero pos

[Joe Grames]

The folks responsible for steering the 2I/1I/0I region were either 
involved in defining the steering protocol or attending the training.  
At some level, Reza, Michele and I "owned" defining the protocol. It can 
certainly be a topic for discussion and changed.  Maybe we (I?) over 
simplified some steps in ~early 2010 in order to benefit the learning 
curves for a fairly significant process change, but many of the hooks 
are already in place to deal with setup steps.  It may be helpful to 
watch the training I gave to Ops - I am pretty sure Tom Oren videotaped 
one of the sessions.  I can also do this, and help collectively evolve 
the process.  In the end, human judgment is ~always required.

On 4/19/2011 10:46 AM, Jay Benesch wrote:
> Matt,
>
> I am saying that the reasons the scraping on A2 affects charge asymmetry
> width were unknown to me, not that they are unknown to everyone.
>
> I hadn't looked at the injector steering screen enough to notice the
> "saved orbit" option.  Perhaps it should be made the default instead of
> "rels".
>
> If Ops can be trained to consistently autosteer the injector to the
> saved orbit with A:C current ratio the same as that used to save the
> orbit, I will be happy.  The steering script would have to provide the
> ratio info in some manner on the screen which means that the person
> saving the gold orbit would have to enter it in a new PV.
>
> [to all] Is getting the current ratio, say 10:16 A:C, sufficient? Or
> does the injector steering need to be done at the full current of the
> original setup to the inline dump, in which case target changes in the
> halls will likely require that injector auto-steering always be done to
> the inline dump.
>
> Jay
>
> On 4/19/2011 10:33, Matt Poelker wrote:
>> And charge asymmetry is related to A2 interception because the beam
>> moves left/right up/down because of helicity correlated beam motion
>> originating at the pockels cell, something QWeak tries to minimize by
>> doing their sensitive shifts-long pockels cell alignment.  Small
>> scraping, smaller charge asymmetry, bifg scraping, bigger charge
>> asymmetry.  Are you saying it behaves differently?
>>
>>
>> Michele Joyce wrote:
>>> FYI, the Injector Autosteer has a feature to use a "gold" orbit saved
>>> by the Injector experts...as opposed to the relative orbit.
>>> Michele
>>>
>>> On 4/19/2011 8:05 AM, Jay Benesch wrote:
>>>> Assertions
>>>>
>>>> 1. with two high current halls the orbit is the weighted average of the
>>>> beam centroids
>>>>
>>>> 2. Qweak charge asymmetry is related, for reasons unknown, to the amount
>>>> of beam scraped off on A2
>>>>
>>>> 3. When Ops does a save with zero position it saves the relative orbit
>>>> for all BPMs
>>>>
>>>> 4. Injector autosteer relies on the relative orbit
>>>>
>>>>
>>>> Conjecture
>>>>
>>>> 0R04 trips may be related to the relative orbits of the A and C beams.
>>>> http://opweb.acc.jlab.org/CSUEApps/elog02/elog_item.php?elog_id=1579572
>>>>
>>>>
>>>> Suggestions
>>>>
>>>> "Zero position" option in SAVER should be modified from yes/no choice to
>>>> three choices:
>>>>
>>>> a. zero position for injector "[0123]I", 0L, 0R
>>>> b. zero position for everything else
>>>> c. no ZP
>>>>
>>>> Ops could choose any one or the a/b pair.
>>>>
>>>> For restore, there could be a few more templates at the end under a BPM
>>>> restore "menu": injector, machine, hall A, hall B, hall C.  Or people
>>>> could simply be required to continue to grep the needed BPMs when
>>>> restoring a relative orbit.
>>>>
>>>> Jay
>>>>
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