[BTeam] Fwd: Injector Alignment

[Reza Kazimi]

I do not  know what the difference between bteam and BTeam.bounces is in the jlab.org mailing system.

Please someone explain why we need this confusion and why BTeam.bounces shows up first with capital letters if it is not the real bteam email. So when I or others send emails to capitalized BTeam does it even go to all members of bteam "directly"? If both email groups are the same can we eliminate one?

So many questions for your weekend.

I'm forwarding Will's email to bteam, I think, maybe, perhaps.

Reza,



Reza Kazimi
kazimi at jlab.org

________________________________
From: Will Oren <oren at jlab.org>
Sent: Friday, October 2, 2020, 3:53 PM
To: Reza Kazimi; Joe Grames; Christopher Curtis
Cc: Chris Gould; Matthew Poelker; BTeam; Camille Ginsburg; Alicia Hofler; Yan Wang
Subject: Re: Injector Alignment

Reza,
This is interesting and reminds me of my old job.   Beamline designers should always keep in mind areas like the injector to N.Linac or beam transport line to Hall "joints"   These areas almost always develop discontinuities over time for a couple of reasons.  The first is quite practical - the civil construction of such places usually involve a structural change resulting in a joint where the two different structures show their relative movement.  The second comes from geometry that us alignment guys can't easily overcome because of lines of sight and usually narrowing areas of access.   These geometric issues also create a "weak joint" between control network structures.

So with that all said, beam line designers should provide for the possibility of extra steering or some other optical compensation for a "joint" in a beamline that correspond to structural joints in the beam enclosure.

Thanks for the flashback to my previous life where I felt a bit more useful.  🙂

Will

________________________________
From: Reza Kazimi <kazimi at jlab.org>
Sent: Friday, October 2, 2020 7:15 AM
To: Joe Grames <grames at jlab.org>; Christopher Curtis <curtis at jlab.org>
Cc: Chris Gould <gould at jlab.org>; Matthew Poelker <poelker at jlab.org>; BTeam <bteam-bounces at jlab.org>; Will Oren <oren at jlab.org>; Camille Ginsburg <ginsburg at jlab.org>; Alicia Hofler <hofler at jlab.org>; Yan Wang <ywang at jlab.org>
Subject: Injector Alignment


I had a good meeting yesterday (Thursday Oct 01-20) with Curtis, Gould, and Grames on Injector Alignment. The decision is to leave things as is.

What does it mean?

(Chris Curtis please correct me if I misstate something)

According to the latest surveys (2008 & 2012) there is an offset of about 1.2 mm in X and 1.5 mm in Z  between injector and North Linac coordinates. Everything before girder 0L03 is aligned to injector coordinates and everything from 0L03 and higher is aligned to NL coordinates.

This situation causes almost no problem for us in operating or modeling of the Injector. Why? Because there is a long drift right before 0L03. A 1.2 mm X offset becomes unnoticeable in a long drift. (Z offset is even more insignificant)

Now, if we attempt to eliminate this coordinates' difference during the Phase 1 of injector upgrade, this 1.2 mm offset will show up next year right at the choppers where the elements are much closer to each other and 1.2 mm offset will all of a sudden become significant.

The other point to consider is that there is no guarantee that the North Linac won't move farther with respect to the injector in future. It may continue in the same direction or reverse course. Since moving all injector back and forth is not practical,  my vote is to take this offset at a location which is least disruptive, and that would be 0L03 girder. In other words don't change anything.

The only problem remains is what Chris Curtis brought up and that is potential for confusion when we align elements in the injector. We should keep clear documentation that 0L03 is the breakpoint and make sure there is no ambiguity in the sign of 1.2 mm.

Chris, if you or other experts in alignment group start a tech note to document this, I would be happy to contribute to any part that falls under my expertise.

I have added more recipients for the email. Please let us know if we are overlooking something important.

Reza,


Reza Kazimi
kazimi at jlab.org


-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://mailman.jlab.org/pipermail/bteam/attachments/20201002/95eec56f/attachment-0001.html>