> Concluding, it is the field map change that made the reconstructed angle
> shift, or am I wrong?
Yes. Crunch with new field map = angle offsets.
> The offsets look quite the same for all combinations pR pL eR eL.
> Is there a possible geometrical effect responsible such as shifts or
> rotations of chambers?
Potential geometric root causes of offsets...
Measured - Calculated(opposite sector Measured) is a negative number for
both sides, therefore: Calculated > Measured. Calculated would be greater than
Measured if the opposite sector also measured an angle that was too small. If the
angle is measured at less than it truly is in both sectors, a few geometric possibilities:
1. Software puts the chambers too far downstream from the target, reconstructs
an angle too small.
2. Software thinks the chambers are tighter than they are, this would result in
smaller momentum and smaller angles.
3. A rotation of the chambers would have opposite effects on electron vs. proton
tracks. The curvature and polar angle would do the opposite for opposite charge.
But this would violate the Calculated > Measured that we are seeing.
If Doug's straight track analysis is correct, I think any geometric shift would have
shown up in his final plots of the track's deviation from a line. From what I understand,
that analysis has told us whether the wires are where we think they are. And
the results, in fact, were that the wires are where we think they are. Taking on that
information as fact, I think we'd have to believe that our survey is correct and that
the tracking problem probably resides in the code or the algorithm.
-eugene
Quoting Michael Kohl <kohlm@mit.edu>:
> Hi Eugene,
>
> I just had a look at your plots of the angle deviations depending on the
>
> recrunch version and correponding assumptions that you posted on Jan 19.
>
> It seems that only the crunch with the new field had the larger angle
> offset.
> You forgot to also plot the actual RECRUNCHDIR result which is Chi's 9th
>
> order in combination with the new field map. I seem to remember that
> this
> also has an angle offset.
>
>
>
> Regards,
>
> Michael
>
>
>
> On Thu, 19 Jan 2006, Eugene J. Geis wrote:
>
> > Weird timing for me to call in today and apologies about not making it
> last week.
> >
> > I made 4 plots of comparisons of the theta_(e/p) -
> theta_e/p(theta_p/e) offsets over the hydrogen
> > directories given to me by Michael. I've uploaded the 4 graphs into
> the meeting_060119 directory on
> > blast02. You should look at the postscript file Theta_pR.ps first to
> see which histogram corresponds to
> > which ANALDIR. The obvious offset is only apparent in Aaron's
> 6thorder recrunch which is the ONLY
> > crunch version that uses the NEW Fieldmap from all of the ANALDIR's
> that I tested. Chi's 9th order
> > crunch in library v15 that uses the OLD fieldmap does not have the
> striking offset. All four postscript
> > files show this same trend. OLD Fieldmap means no striking theta_e -
> theta_e(theta_p) offset.
> >
> > Also as an update for GEn analysis, I'm piping Vitaly's data into my
> code to verify asymmetries. We still
> > have some glaring discrepancies.
> >
> > eugene
> >
> > Quoting Douglas Kenneth Hasell <hasell@MIT.EDU>:
> >
> >> Dear Colleagues,
> >>
> >> As decided during last week's analysis meeting: this week's
> analysis
> >>
> >> meeting will be on Thursday (Wednesday there is a lunch for Chris
> >> Tschalar) at 14:00.
> >>
> >> Attached are the minutes from last week's meeting.
> >>
> >>
> >>
> >> Cheers,
> >>
> >>
> >> Douglas
> >>
> >> 26-415
> >> M.I.T.
> Tel:
> >>
> >> +1 (617) 258-7199
> >> 77 Massachusetts Avenue Fax: +1
> >> (617) 258-5440
> >> Cambridge, MA 02139, USA E-mail:
> >> hasell@mit.edu
> >>
> >>
> >
> >
> >
> >
> --------------------------------------------------------------------------
> > Eugene Geis
> > PhD Student, Physics Department, ASU
> > Research Affiliate, MIT-Bates Laboratory of Nuclear Science
> > eugene.geis@asu.edu
> >
> --------------------------------------------------------------------------
> > http://quickreaction.blogspot.com
> >
>
>
> +-------------------------------------+--------------------------+
> | Office: | Home: |
> |-------------------------------------|--------------------------|
> | Dr. Michael Kohl | Michael Kohl |
> | Laboratory for Nuclear Science | 5 Ibbetson Street |
> | MIT-Bates Linear Accelerator Center | Somerville, MA 02143 |
> | Middleton, MA 01949 | U.S.A. |
> | U.S.A. | |
> | - - - - - - - - - - - - | - - - - - - - - -|
> | Email: kohlm@mit.edu | K.Michael.Kohl@gmx.de |
> | Work: +1-617-253-9207 | Home: +1-617-629-3147 |
> | Fax: +1-617-253-9599 | Mobile: +1-978-580-4190 |
> | http://blast.lns.mit.edu | |
> +-------------------------------------+--------------------------+
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
--------------------------------------------------------------------------
Eugene Geis
PhD Student, Physics Department, ASU
Research Affiliate, MIT-Bates Laboratory of Nuclear Science
eugene.geis@asu.edu
--------------------------------------------------------------------------
http://quickreaction.blogspot.com
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