Re: angle offsets

From: Michael Kohl (kohlm@mit.edu)
Date: Mon Feb 06 2006 - 15:12:55 EST


Hi,

my understanding is that the wires are within a chamber where you expect
them, but the 6 chambers are not necessarily where we think they are.

Regards,

    Michael

On Mon, 6 Feb 2006, Christopher Crawford wrote:

> Hi Eugene,
> Have Doug's results changed? Last I heard, the right sector middle chamber
> was shifted by 1.2 mm.
> --Chris
> _______________________________________
>
> TA-53/MPF-1/D111 P-23 MS H803
> LANL, Los Alamos, NM 87545
> 505-665-9804(o) 665-4121(f) 662-0639(h)
> _______________________________________
>
>
> On Feb 6, 2006, at 12:23:16, Eugene J. Geis wrote:
>
>>> 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 |
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>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>
>>
>>
>> --------------------------------------------------------------------------
>> 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 |
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| Middleton, MA 01949 | U.S.A. |
| U.S.A. | |
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