Hi John,
thanks for your reply. and also thanks go to Karen and Pete for the
replies as well.
so, here we do not disagree at all. ie., there is a big problem with
the detection. but if you just want to fish for whatever events
you can get, then it is fine with me or anybody. otherwise, it might make
more sense to focus on gamm-pi channels with vector hydrogen or deuterium
targets.
however, i still have one more comment on anticipated deuteron gamm-pn
tensor asymmetries:
i had bunch of calculations from Michael Schwamb in 2002 left on
my mit computer somewhere. i do not know whether you have contacted
Michael directly for the calculations. nevertheless, there are some
problems with the existing blast runs (or data on tapes) regarding the
spin alignment. if there is no other spin alignment planned, then the
photo channel asymmetries would be roughly zero (at 300 MeV)
with the existing data. so that the measurement would be a null one.
at 300MeV with tensor spin at left 30deg, your experimental asymmetry
roughly = 0.5 T20 + 0.3 T22 = 0.5*0.6 - 0.3 * 0.9 ===> 0.0
of course, this would not be what anybody wants.
please let me know if you think i am wrong.
Zilu
At 03:02 PM 9/9/2004 -0400, John Calarco wrote:
>Hi Zilu
>
> Regarding D(gamma,pn) at 100 MeV (or lower) you are correct that the
>BLAST acceptance vanishes. The opening angle between the p and n for
>approximately symmetric breakup varies roughly linearly with photon
>energy from about 161 deg at 100 MeV to 147 deg at 300 MeV. So the
>acceptance vanishes near 100 MeV, neglecting curvature in the BLAST
>field. The curvature makes things worse, raising the effective photon
>energy where the acceptance becomes non-zero, at least for normal field
>which covers most of the available data.
>
> John
>
>
>--
>John R. Calarco
>Dept. of Physics
>Univ. of New Hampshire
>Durham, NH 03824
>phone: (603)862-2088
>FAX: (603)862-2998
>email: calarco@unh.edu
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