Hi Boss, will the lunch be provided? :)
seriously, the things I got asked about this morning at meeting.
1. in terms of the errors between 32 and 45 deg runs. turns out with 45(or
47 or whatever in that neighborhood), errors on T20 are only marginally
better than with 32 deg. we are talking about +-0.15 vs +-0.14 type of
difference.
2. in terms of spin angle error, I guess I was too conservative seeing the
pre July data with low polarization and bad tracking and stuff. Boy
those data are a misery to look at.
With current Pzz (>~0.6), with same counts as we collected from July to
Oct, I believe now average spin angle can be measured by T20 to +-0.5~0.6
degrees.
Another method to esitmate this error, proposed by Genya, is also used to
check this estimation. it gives a bit more optimistic estimation, arround
0.4 deg. But in the spirit of Murphy's law, which I now firmly believe is
as true as the 2nd law of thermal dynamics, I tend to believe even +-0.5
is a rather optimistic estimation. :)
3. a spin angle profile as seen by ed elastic. please see the attatched
plot. the black curve is the "scaled to 32 deg" profile. It takes the 47
degree profile, scaled the tangent of angle at any point by
tan(32)/tan(47). the purple data points are spin angle measured from ed
elastic by cutting the target length into intervals. the division of the
-20 to 20cm range is such that each interval contains roughly equal
counts. data seem to want to dip more. I say we should let a actual survey
speak.
To beat on actual survey, I still believe the field mapping is THE right
way to control spin angle. T20 measurement or whatever measurement from data
should be taken only to monitor and/or confirm the survey result and to
make sure that problems would be quickly spotted if there were any
problems, such as a shorted coil, which motivated the T20 spin angle
measurement ealier in 2004 anyway.
About the event by event correction of spin angle. it is done in ed
elasitc channel with the "fudged" angle profile. All the programs and
infrastructures are constructed months ago, the one single missing
piece is the map.
Chi
On Wed, 19 Jan 2005, Tancredi Botto wrote:
>
> Following today's discussion I suggest an agenda for our meeting with
> D. Philips next week, assuming we have regular blast meeting at 9.00.
>
> Maybe D. Philips talk could be anticipated to 13.30 to suit Richard
> travel needs. Let me know what you think.
>
>
> 10.30 AM: Overview BLAST detector, BLAST spin dependent eep asymmetries vs
> pmiss
> 10.45 VZ: GEn measurament
>
> 11.00 CZ: BLAST T20 measurament, and discussion of its normalization
>
> 12.00 Lunch (Bates library)
>
> 14.00 D. Philips talk
>
> 15.00 General discussion
>
> --
> ________________________________________________________________________________
> Tancredi Botto, phone: +1-617-253-9204 mobile: +1-978-490-4124
> research scientist MIT/Bates, 21 Manning Av Middleton MA, 01949
> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>
>
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