?????? ?????????????? ?? ?????????????? ???????? ? ????????? ??????? 680-1500 ??? ?.??????, ?.???????, ?.?????, A.???????????, ?.?????????, A.??????? ??? ???????????? GRAAL ???????? ??????? ???????????? ???

1
?????? ?????????????? ?? ??????????????????????
? ????????? ??????? 680-1500 ??? ?.??????,
?.???????, ?.?????, A.???????????, ?.?????????,
A.??????? ??? ???????????? GRAAL????????
??????? ???????????? ???

• ???????????? ????? ????????????????? ?????? ?
  ???????? ??????? ?????????????? ?? ???????,
  ???????? ? ????? ???????? ? ????????? ???????
  g-??????? Eg 680 -1500 MeV. ????????? ????
  ????????? ?? ????????? GRAAL. ??? ?????????
  ??????? ???????? ??? ??????????? ??????
  (????????? ???? ? ???????????? ???????????
  ???????) ???? ????????????. ???? ????????, ???
  ??????? ????? ????????? ??????? ?????????????? ??
  ?????????????? ??????? ? ?????????????? ????????
  ?? ????????? 5. F15 (1680 MeV) ????????,
  ??????????? ??? Eg1000 MeV, ?????? ????? ??
  ????? ????????. ????????? ??????????? ???????
  ???????????? ??????? ?? ????????? ?
  ?????????????? ??????? ????????? ??????? ?????,
  ??? ??????? ??????? ????? ??????????? ?? ??????
  ?????-?????????, ?? ????? ? ??????????????
  ???????????? ? ???????? ?????????.

2
Scheme of the GRAAL experiment
3
Previous experiment on free proton data
Partial p0 photo-production cross section on the
proton, measured with different wave length laser
light. Green and red points correspond to 340 and
514 nm, respectively. Curve represents the
prediction of SAID.
Total photoabsorption cross section on the free
proton obtained by the subtraction method. Full
dots, triangles, and circles represent the GRAAL,
Mainz, and Armstrong data, respectively.
4
Subtraction method
Selection of a proton and charged pion in BGO
detector
Total yield from the full target (open circles),
empty target (full triangles) and their
difference (full squares) .
5
Cross section evaluation method
Photon flux (a), yield (b), measurement
efficiency (c) (reaction gpgtpp0 ). Cross section
(d) is obtained by division of the yield on the
flux, and normalized on the measurement
efficiency and thickness of the target.
6
Partial cross sections for one and double pion
and h meson photo-production on free and
quasi-free proton and quasi-free neutron Red
free proton, green quasi-free proton, blue
quasi-free neutron.
Specific media modification in different channels
indicates that two nucleon correlations plays
important role in addition to Fermi motion.
7
Total photo-absorption cross section for
the deuteron, obtained by subtraction (open
points) and summing method (full points) in
comparison with literature Armstrong data (full
triangles)
Results obtained by two different methods
coincide within 5 error bars in the energy
region up to 1.2 GeV. Above this energy, there is
seen a noticeable disagreement, which is
explained by the triple meson production channels
contribution which was not included in the
present evaluation of partial channels. We see
the similar relative behavior, especially
presence of the F15 (1680) resonance in the cross
sections, obtained by subtraction and summing
methods in contradiction with the Armstrong data
seen.
8
Total photo-absorption cross section for the 12?.
Crosses correspond to GRAAL data, obtained by the
subtraction method. Full and open points are
taken from Bianchi e. a. and Mirazita e. a. data,
respectively. Universal curve is marked by the
full line. Good agreement with earlier published
results and the universal curve is seen.
9
Comparison of the total photo-absorption cross
sections for the proton (full triangles),
deuteron (open points) and carbon (full points).

The carbon cross section is in 30 less than the
free proton and deuteron one.
10
??????????? ??????? ?? ?????????????? ???????.
??????? ?????? - ????? ????? ???????????
?????????
11
??????????? ??????? ?? ?????????????? ????????.
??????? ?????? - ????? ????? ??????????? ?????????
12
Total photo-absorption cross sections on bound
proton (green points) and neutron (red points)
obtained by the summing method (deuteron target)
Slight (5) but systematic difference in the
absolute scale above 1 GeV can be caused by the
neutron efficiency uncertainty.
13
Comparison of the total photo-absorption cross
sections on free and quasi-free proton(actinide
nuclei)
Dotted line and triangles free proton
(Armstrong and GRAAL data, respectively) Full
points GRAAL data for carbon
Dotted line free proton Dashed line and points
nuclei from 7Li to 238U Solid line actinide
nuclei (CEBAF data)
Carbon and actinide nuclei cross sections are
very close in absolute scale.
14
??????

• ??????? ??????? ??????????????, ??????????
  ??????? ????????? ???? ? ??????? ????????????
  ??????????? ??????? ????????? ? ????????? ?? ????
  5 ?? ??????? g-??????? 1,2 ???. ??????????? ????
  ???? ??????? ??????????? ????????? ???????????? 3
  ? ????? ???????.
• ??????????? ??????? ? ??????? ????? ???????????
  ?? ?????? ?????-?????????, ?? ????? ?
  ?????????????? ???????????? ? ???????? ?????????.
• ??????? ??????? ?????????????? ?? ????????
  ??????????? ????????? ? ????????????? ??????,
  ?? ????? ?? 30 ???? ????????? ? ??????????
  ??????
• ????? ????????????????? ?????? ?? ?????? ????????
  ?????????????? ?? ???????? ????????? ??
  ???????????? ?????? ??????? ?????????????? ??
  ??????? ? ???????? ? ??????? ????????? ??????????
  ? ????????? 5. ??? ???????? ? ?????????
  ???????????? ??????? ?????????????? ????, ?????
  ????????????? "????????????? ??????",
  ????????????? ????????? ?????? ???? ? ??????
  ??????????????? ?????????? ?? ????????
  ???????????????? ?????????????? ????.