Re: [BLAST_ANAWARE] Minutes of the 3/23/5 analysis meeting

From: Octavian F Filoti (ofiloti@cisunix.unh.edu)
Date: Thu Mar 24 2005 - 12:40:54 EST


Some mistakes: trigger# 7 itself for singles gives bad results!
Better results I get when I use both trigger # 2 and 7! If I want to use
trigger # 1 also (add to #2 and #7), I need to take into account the
elastic tail!

-----------------------
Octavian F Filoti
Nuclear Physics Group
Univ. of New Hampshire
9 Library Way
Durham, NH 03824
phone: (603)862-1220
FAX: (603)862-2998
email: ofiloti@unh.edu

On Wed, 23 Mar 2005, Michael Kohl wrote:

> Analysis meeting minutes:
> Attending EG, NM, TF, TA, DH, BT, AS, CC, MK.
>
> -"Big" Analysis meeting scheduled for Wednesday 4/61/2005
> (*not* Thursday!!)
>
> -EG:
> +Finds discrepancy for (e,e'n) yields from flr and dst for runs in
> the 8000's, however those still have no useful dst, only after
> recrunch. Should use new runs of this year instead which do have
> proper dst.
> +Reports (e,e'n) yields have decreased this year compared to last
> year because of lower target density (this may depend on particular
> run numbers), however relative to proton yield it is unchanged.
> +Should investigate if this also applies to the forward LADS wall
> (above Q2=0.4, or cut on L15), when normalizing (e,e'n) yields to the
> (e,e'p) rate in order to see if installing the lead
> shieldings/converters had any effect
> +Will get started with Tosca soon
>
> -TF:
> +Presenting inclusive-ep beam-target asymmetries compared to MC
> with MAID implemented.
> +Aleft and Aright for different trigger types, also A_TT' and A_TL'
> +Trigger type 7 agrees with MC
> +TF-MC and AS-MC agree
> +Trigger type 1 asymmetry is shifted to negative direction.
> Qualitative understanding is that the radiative tail of elastic
> scattering events contributes to the inclusive yield in the
> Delta-region, however only in trigger 1 and not in 2 (e,e'n) or 7
> (singles). Asymmetry attributed to elastic events is negative.
> Somewhat but not drastically different asymmetry of tail-events
> compared to unradiated events expected due to kinematics effect (q2
> different)
> +AS claiming that radiative tail does not explain quantitatively the
> discrepancy of measured asymmetry and MC.
> +In order to gain confidence into the implementation of MAID into
> BLASTMC, one needs some benchmarking. Possible checks are comparison
> of BLASTMC with MAID prediction for pointlike kinematics at prominent
> points (at top of Delta). MAID may not be the last word for
> polarization observables and the multipoles probed. The unpolarized
> case is much better known. Since the electron efficiency for
> inclusive scattering should be on the order of 80% and for a
> luminosity taken from ep elastic scattering, one could determine the
> differential cross section (unpolarized) to some limited precision
> which should be reproduced by MAID (dominant M1 multipole).
> +Different trigger types have different backgrounds; background may
> even be polarized as in above case. Polarized radiative-tail
> background should be handled in BLASTMC with MAID+radiation tail in
> generator.
>
> -NM:
> +Made MASCARAD to work, converted to C++ from Fortran. MASCARAD
> accounts for the Mo and Tsai radiative effects for elastic
> scattering including the helicity-dependent part.
>
> -We should have radiative effect in generator. May not be so important
> for asymmetries in elastic scattering, however it is important for
> the estimate of the contribution by radiated elastic events in the
> Delta region.
>
> -CC:
> +Showing ep elastic data and MC asymmetries and polarizations
> +Slight disagreement between MC and Hoehler-pointlike
> +Some cluster-like over-and undershooting of the Hoehler curve
> +Q2-dependence of PbPt gone after cutting more strictly on
> wirechamber hits. Data sample became smaller, polarization higher.
> +Kinematical corrections: Trust angles, calculate momenta from angles
> for elastic scattering -> p_exp-p_calc(the):the etc. for eleft,
> pright and vice versa. Seems to observe somewhat different results
> than EG (needs to be compared explicitly.)
> +p_exp-p_calc(theta):p_exp for eleft, pright, eright and p_left
> should be plotted and made available as a third set of kinematical
> corrections and be compared to the ones by AM and EG.
> +z_electron-z_proton is not zero and has opposite sign when sectors
> are flipped. Possible explanation may be a transverse offset of the
> target, beam, or wire chamber. If so, dz versus theta should cross
> zero at 90 degrees.
>
> Regards,
>
> Michael
>
>
> --
>
> +-------------------------------------+--------------------------+
> | 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 | |
> +-------------------------------------+--------------------------+
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