Hi,
the meeting's focus was a review of radiative effects.
Agenda:
-Introduction to radiative effects (CC)
-Precise calculation vs. helicity-independent only: how good is the
approximation?
-Precise calculation vs. peaking approximation: how good is the
approximation?
-Relevance to BLAST observables (elastic, quasielastic, inelastic)
-Handling by other labs (Jlab, Mainz)
-Traditional way of unfolding radiative effects
-Implementation into generator (MASCARAD, etc.)
-What actions have BLAST-analysts taken so far? (NM,VZ,TF,PK,CC,AM,...)
-Outline of a way to proceed
Chris gave not only an introduction but a very comprehensive presentation
and discussion on all points of the agenda. Please refer to his slides at
http://blast.lns.mit.edu/PRIVATE_RESULTS/USEFUL/ANALYSIS_MEETINGS/meeting_050630/rc_overview.ppt
We also discussed:
External vs. internal radiation: All efforts to calculate radiative
effects in CC's talk refer to internal radiation.
Polarization effects may be present for outgoing polarized particles or of
the polarized beam in thick targets.
However, if the target is thin -> no external radiation of the target.
Soft Photon Approximation (=Mo+Tsai) implies asymmetries are not affected
SPA based on OPE-Born and me=0.
Elastic and quasielastic asymmetries are expected to change by no more
than 1% due to the polarization-dependent radiative effects (to be
quantified).
MASCARAD is the code for polarized radiative effects for proton target,
now implemented into blastmc.
Extensions for elastic and quasielastic scattering from the deuteron is
in progress.
For the inclusive N-Delta channel, it is essential to simulate the
radiative tail of elastic scattering ranging into the inelastic region.
For the future blastmc for NDelta the radiated generator should be
combined with MAID and the various trigger types should be handled
separately.
Moreover, the radiation by inelastically scattered electrons may be more
sensitive to polarization effects than in the elastic case. In addition,
the produced pions themselves may contribute significantly as their mass
is much smaller than in the corresponding case of radiating protons
(negligible).
The next analysis meeting will be on Wednesday 2005/07/06, with the
efforts in calibration and recrunching in focus.
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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