[Bteam] injector relative orbit and zero pos

[Jay Benesch]

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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