Actually what we (I) had in mind was to see if there is any movement between the most recent powerings of SSD and SSU.
These were on 1,2,3,8 and 11 July.
Twists (rotations) would be interesting to know about.
Things could well have moved since February.
jhc
> -----Original Message-----
> From: MICE Magnets [mailto:[log in to unmask]] On Behalf Of
> Chris Rogers
> Sent: 12 July 2016 17:26
> To: [log in to unmask]
> Subject: Fwd: Re: Alignment
>
> Mike and Josef were curious about our alignment numbers from data
> analysis. Please see the emails below. The upstream tracker TKU appears to
> have moved by a couple of mm transverse between September 2015 and last
> weekend. Francois is running the numbers on the February data.
>
> Note these are transverse alignments. We have little/no resolution on
> longitudinal (z) alignment and roll.
>
> alpha is rotation about the horizontal axis and beta is rotation about the
> vertical axis.
>
> Cheers,
> Chris
>
> -------- Forwarded Message --------
> Subject: Re: Alignment
> Date: Tue, 12 Jul 2016 17:04:54 +0100
> From: François Drielsma <[log in to unmask]>
> To: Chris Rogers <[log in to unmask]>
>
> Hi Chris,
>
> Theoretically there should not be any bias as it is the purpose of the
> selection. In my opinion there's two possibilities:
>
> - The trackers actually moved, especially TKU as it seems that TKD is
> not extremely far off.
> - There is an issue with how the geometry gets the position of the
> TOFs
> from the survey.
>
> The fact that it is consistent between the different runs (200, 300, 400),
> once again, makes me think that the alignment code is doing what it's
> supposed to do.
>
> I need to pull the Feb/March data and I'll run the alignment on it as
> well, I'll let you know how it comes out.
>
> Best,
> Francois
>
> 2016-07-12 16:59 GMT+01:00 Chris Rogers <[log in to unmask]>:
>
> > So from your note (data taken in September 2015) I get:
> > X Y ALPHA BETA
> > TKU -0.075 -1.796 3.151 0.768
> > TKD -2.380 +2.549 -0.627 1.073
> > with about 0.25 mm and 0.08 mrad precision on alignment
> >
> > From these plots (data taken over the weekend)
> >
> > X Y ALPHA BETA
> > TKU +2.281 -0.482 3.51 -0.293
> > TKD -2.951 +2.899 -1.23 +0.933
> >
> > with about 0.09 mm and 0.03 mrad precision on the alignment.
> >
> > Systematic errors:
> >
> > TOF1/2 survey -> 100 micron?
> >
> > anything else? What is the scraping error systematic? Do you assert
> zero?
> > Is there any systematic from beam impurity? Anything else?
> >
> > The magnet folks were interested in whether the trackers had moved
> > since they last powered the magnet... would be interesting also to
> > look at the alignment from Feb/March data...
> >
> > Cheers,
> > Chris
> >
> >
> >
> > On 12/07/16 15:23, François Drielsma wrote:
> >
> >> Hello Chris,
> >>
> >> I've gone through the alignement data and everything seems pretty
> >> good. I do, however, find that some the parameters have changed a
> >> bit. Not sure if it's a real concern or not. I attached the best fits
> >> for all the alignment runs. The bin labelled 07992 contains
> >> 07992-08000 and 08015, i.e. all of the 200 MeV/c setting.
> >>
> >> Best,
> >> Francois
> >>
> >>
> >
> > --
> > ASTeC Intense Beams Group
> >
> > tel: +44 (0)1235 44 6983
> >
> > Building R2,
> > Rutherford Appleton Laboratory,
> > Harwell Science and Innovation Campus, Didcot.
> > OX11 0QX
> >
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