Forward-angle pion inelastic scattering

Technical Report · Sun Jan 01 04:00:00 EST 1984

OSTI ID:5209634

Bland, L C

Forward-angle pion inelastic scattering was measured for /sup 12/C, /sup 28/Si, and /sup 40/Ca to search for the predicted (but previously unobserved) spin-flip dipole state in these nuclei. Pion inelastic scattering angular distributions at T/sub pi/ = 164 MeV were also measured for the isoscalar, natural-parity states of /sup 16/O and low-lying monopole states in /sup 12/C and /sup 28/Si to test the distorted-wave impulse approximation (DWIA) model of pion inelastic scattering. Existing structure information for these states enabled this quantitative test of the DWIA model. Generally, good agreement was found between these calculations and the data. Large discrepancies were observed, though, for the /sup 16/O(1/sub 1//sup -/. 1/sub 1//sup 4/, 0/sub 3//sup +/) states and the forward-angle cross sections for the /sup 12/C(0/sub 2//sup +/) state. These discrepancies demonstrate the need for the contribution of higher-order processes to pion scattering. The forward-angle measurements on /sup 12/C and /sup 28/Si revealed the existence of forward-peaking angular distributions for states in the giant resonance region of these nuclei. Comparisons with DWIA calculations employing a transition density for a state exhausting the spin-flip dipole transition strength from the ground state indicate the present results have located a significant fraction of the expected strength. The present measurements are not sufficient to exclude the possibility that the observed forward-peaked enhancements are fragments of the giant monopole resonance. The observed strengths are inconsistent with extensive measurements performed with other probes if this were the correct interpretation. This indicates that a large fraction of the expected isoscalar, spin-flip dipole strength is concentrated in states which lie lower in excitation energy than the giant dipole resonance.

• Research Organization: Los Alamos National Lab., NM (USA)
• DOE Contract Number: W-7405-ENG-36
• OSTI ID: 5209634
• Report Number(s): LA-9960-T; ON: DE84008367
• Country of Publication: United States
• Language: English

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73 NUCLEAR PHYSICS AND RADIATION PHYSICS
ALKALINE EARTH ISOTOPES
ANGULAR DISTRIBUTION
CALCIUM 40
CALCIUM 40 TARGET
CALCIUM ISOTOPES
CARBON 12
CARBON 12 TARGET
CARBON ISOTOPES
CHARGED-PARTICLE REACTIONS
CROSS SECTIONS
DATA
DISTORTED WAVE THEORY
DISTRIBUTION
ENERGY LEVELS
ENERGY RANGE
ENERGY-LEVEL TRANSITIONS
EVEN-EVEN NUCLEI
EXCITATION FUNCTIONS
EXPERIMENTAL DATA
FUNCTIONS
GIANT RESONANCE
HADRON REACTIONS
IMPULSE APPROXIMATION
INELASTIC SCATTERING
INFORMATION
ISOTOPES
LIGHT NUCLEI
MESON REACTIONS
MEV RANGE
MEV RANGE 100-1000
NUCLEAR REACTIONS
NUCLEI
NUMERICAL DATA
PION REACTIONS
RESONANCE
SCATTERING
SILICON 28
SILICON 28 TARGET
SILICON ISOTOPES
SPIN FLIP
STABLE ISOTOPES
TARGETS
THEORETICAL DATA