Studies of spin excitations with electromagnetic and hadronic probes

Conference · Fri Jan 01 04:00:00 EST 1982

OSTI ID:5466574

Lindgren, R A; Petrovich, F

Excitation of unnatural parity states, predominantly of high spin, using electromagnetic and hadronic probes, is discussed. Spectroscopic strengths are deduced from studies of (e,e'), (p,p'), (..pi.....pi..'), and (p,n) for states whose doorway is the stretched particle-hole configuration. These levels are excited primarily through the isovector electromagnetic-nucleon magnetization coupling, nucleon-nucleon tensor coupling, and pion-nucleon spin-orbit coupling. The extracted isovector spectroscopic strength is typically 38% of the extreme single particle-hole model and about 66% of that predicted by more realistic nuclear structure calculations. The observed isoscalar strength is only about one half of the isovector strength. The results obtained with the three different probes are quite consistent. The primary conclusion is that the missing strength for these high spin excitations is at least as large as for the low spin M1 and GT excitations. This implies the existence of other important quenching mechanisms since the ..delta..-N/sup -1/ mechanism involved in the discussion of the low spin excitation affects only the isovector transitions and contributes little to high spin excitations. A method for using (e,e') and ..pi../sup +//..pi../sup -/ cross section ratios to separate and determine the absolute isoscalar and isovector spin densities for T/sub 0/ to T/sub 0/ transitions in N is not equal to Z nuclei is also discussed and some comments on extracting information from (e,e') and (p,p') studies at high q on low spin 1/sup +/ and 2/sup -/ levels are presented. 78 references.

• Research Organization: Massachusetts Univ., Amherst (USA). Dept. of Physics and Astronomy; Florida State Univ., Tallahassee (USA). Dept. of Physics
• DOE Contract Number: AC02-76ER02853
• OSTI ID: 5466574
• Report Number(s): DOE/ER/02853-20; CONF-820357-9; ON: DE84002648
• Country of Publication: United States
• Language: English

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73 NUCLEAR PHYSICS AND RADIATION PHYSICS
ANGULAR MOMENTUM
BARYON REACTIONS
CHARGE-EXCHANGE REACTIONS
CHARGED-PARTICLE REACTIONS
COUPLING
CROSS SECTIONS
ELECTRON REACTIONS
ENERGY LEVELS
ENERGY-LEVEL TRANSITIONS
EXCITATION
HADRON REACTIONS
HIGH SPIN STATES
INELASTIC SCATTERING
ISOVECTORS
LEPTON REACTIONS
MATHEMATICAL MODELS
MESON REACTIONS
NUCLEAR MODELS
NUCLEAR REACTIONS
NUCLEI
NUCLEON REACTIONS
PARITY
PARTICLE PROPERTIES
PARTICLE-HOLE MODEL
PION REACTIONS
PROTON REACTIONS
SCATTERING
SPIN
TENSORS
VECTORS