[Bteam] injector relative orbit and zero pos

[Matt Poelker]

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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