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MEASUREMENT OF ANN FOR [MATH] ELASTIC SCATTERING IN THE COULOMB INTERFERENCE
REGION
G. Pauletta
To cite this version:
G. Pauletta. MEASUREMENT OF ANN FOR [MATH] ELASTIC SCATTERING IN THE
COULOMB INTERFERENCE REGION. Journal de Physique Colloques, 1985, 46 (C2), pp.C2-459-
C2-461. �10.1051/jphyscol:1985255�. �jpa-00224570�
Résumé - A O N a été mesuré pour la diffusion élastique ?J a 1.46 et 1.28 GeV/c dans la région d'interférence de Coulomb. Résultats préliminaires sont présentés.
JOURNAL DE PHYSIQUE
Colloque C2, supplement au n°2, Tome 46, fevrier 1985 page C2-459
MEASUREMENT OF AN N FOR p p ELASTIC SCATTERING IN THE COULOMB INTERFERENCE REGION +
G. P a u l e t t a
University of California at Los Angeles and University of Texas at.Austin, U.S.A.
Abstract - A N N fo r ?? elastic scattering has been measured at 1.47 and 1.28 GeV/c in the Coulomb interference region. We present preliminary results of the measurement.
Measurements of A O L and Aox are the only effective experimental constraints presently available to determine the forward parts of the pp elastic double-spin- flip amplitudes at intermediate energies. These data, which fix the imaginary parts of the amplitudes, display pronounced energy-dependent structure./l/ Knowledge of the corresponding real parts is important for the interpretation of the structure, particularly in the light of speculations concerning the existence of dibaryon resonances. Up to the present time, we have depended on the semiphenomenological predictions of forward dispersion relations /2/ (FDR) for this information.
The measurements reported here are the first of a series designed to determine the real parts of the double-spin-flip amplitudes at forward angles. This is done by measuring the spin-correlation parameters A L L , *NN» *gg, and A L S in the Coulomb-interference region./3/ The measurments are analogous to those commonly per- formed to determine the real part of the spin-independent amplitude./4/ However, due to the difficulty of measuring elastic scattering parameters at forward angles with polarized targets, they have not been attempted to date. Together with the measurements of A O L and Aor, they will determine both the modulis and the phases of the double-spin-slip amplitudes.
The measurements have been extended to angles of overlap with data from conventional experiments in order to check reproducibility and to obtain complete angular dis- tributions. These can be used to determine A O L (inelastic) and Aoj (inelastic) because;
AoL(inelastic) » AoL(Tot) - /ALL(do/dB)dS Aar<inelastic) = Aor(Tot) - /(ANN+Ass)(da/dft)da
These data will help to define inelasticities and lead to less ambiguous interpreta- tion of the energy-dependent structure in their total counterparts. This is because the structure is known to originate principally in the inelastic channels. Present estimates /5/ of the total inelastic cross sections in pure spin states must rely on extrapolations of the correlation parameters from 30° to 0° ( c m . ) .
The measurements are being performed at the Los Alamos Meson Physics Facility (LAMPF), using the High Resolution Spectrometer (HRS) to identify protons scattering from polarized protons in an N-type spin-frozen polarized target. The dilution refrigerator which was provided by KEK was designed to have thin windows in the path of the beam and of the scattered protons in order to minimize straggling and
Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:1985255
C2-460 JOURNAL DE PHYSIQUE
scattering from the heavier target constituents. Despite unusually high beam intensities (up to 108 p/cm2/sec) and the low holding fields (3-4kG), temperatures are low enough (20-50mK) to obtain relaxation times 210 hours. Both the beam and target polarizations (or their product) are monitored continuously by means of a polarimeter viewing the target. An independent measurement of the beam polarization is obtained by means of the Quench method /6/ ANN was measured in September 1983 at 800 and 650 MeV. Preliminary data are shown in Fig. 1. Due to finite azimuthal acceptance, the data forward of -lo0 cm is contaminated by up to a 20% contribution from ASS. This contribution will be corrected for when we have completed the measurement of ASS. ALL was measured at the same energies in July-August 1984.
Analysis is in progress.
0 (DEG.)
cm.
0.6 - -
- -
z 0.4 - -
z - -
a -
-
PRELIMINARY DATA -
Fig. 1. - ANN(&,) at 1.46 GeV/c;
(*)this experiment, (+)Ref. 6, predictions of Virginia PSA (Ref. 7) (hadronic + e.m.), --ibid. (hadronic only).
-0.2
G. ~aulettal, M. ~azzaly', N. ~ a n a k a ~ , B. as', R. caldwel13, W. coulter3,
F. ~ujisawa', S. ~ r e e n e ~ , H. ~ a s a i ~ , S. 1sagawa5, G. fgol, S. 1shimoto5, J. ~ a r m e r ~ , K. ones^, D. Lopiano1, A. ~ a s a i k e ~ , J. ~ c ~ l e l l a n d ~ , C. orris^, F. ~ishiyama~, Y. Ohashil, P. Oillataguerrel, A. 0kihana6, F. sperisenl, G. westonl, C. mitten1, and D. ~usnukis
-
C-
- -
1 1 1 1 1 1 1 1 1 1 1 1 1 1
l~niversit~ of California at Los Angeles, Los Angel~s, CA 90024, U.S .A.
2~niversity of Minnesota, Minneapolis, MN 55455, U.S .A.
3 ~ o s Alamos National Laboratory, Los Alamos, NM 87544, U.S.A.
4~iroshima University, Hiroshima, Japan
5 ~ h e National Laboratory for High Energy Physics (KEK), Ibaraki, Japan 6~yoto University of Education, Kyoto, Japan
8 16 24 32 4 0 48 5 6
References
1. Yokosawa, A., Phys. Rev. 66, 47 (1980) and references therein.
2. Grein, W. and Kroll, P., Nucl. Phys. m,.
505(1982).
3. Lechanoine,
C.,et al., Nuovo Clm. z, 201 (1980).
4 .
