Exclusive quasi-deuteron absorption of pions in /sup 16/O and /sup 18/O at 116 MeV

Journal Article · Tue Nov 01 00:00:00 EST 1988 · Phys. Rev. C; (United States)

DOI:https://doi.org/10.1103/PhysRevC.38.2205· OSTI ID:7084737

Schumacher, R A; Amaudruz, P A; Ingram, C H.Q.; Sennhauser, U; Breuer, H; Chant, N S; Feldman, A E; Flanders, B S; Khazaie, F; Mack, D J; others, and

The reaction /sup 16/O(..pi../sup +/,2p)/sup 14/N was measured at T/sub ..pi../ = 116 MeV with an excitation energy resolution between 1.6 and 2.5 MeV with one proton angle fixed at 50/sup 0/ and for a wide range of the second angle. Proton angular correlations, energy sharing distributions, and recoil momentum distributions for four strongly populated states are consistent with a model of pion absorption on quasi-deuteron pairs with angular momentum transfer to the recoil nucleus of L = 0 (3.9 MeV state), L = 2 (7.0 and 11.0 MeV states), or a mixture of L = 0 and L = 2 (ground state). Integration of the measured absorption cross section over angle and up to 20 MeV of excitation shows that 19 +- 4% of the total absorption cross section can be found in two-proton final states near quasifree kinematics, with substantial additional two-nucleon strength between 20 and roughly 50 MeV of excitation. With estimated corrections for final-state interactions, about half of the absorption cross section below 20 MeV excitation proceeds via the direct quasifree ..pi..pn..-->..pp process. Absorption leading to the T = 1 state at 2.3 MeV is <5% as strong as absorption to the T = 0 ground state. The /sup 18/O(..pi../sup +/,2p)/sup 16/N reaction was measured under the same kinematic conditions. States of less than 0.4 MeV excitation, which correspond to absorption on nucleons in different shells, account for at least 6.1 +- 0.6% of the estimated two-nucleon absorption cross section below 20 MeV excitation; no unexpected suppression of cross-shell absorption was found.

• Research Organization: Paul Scherrer Institute, CH-5234 Villigen, Switzerland
• OSTI ID: 7084737
• Journal Information: Phys. Rev. C; (United States), Vol. 38:5
• Country of Publication: United States
• Language: English

Related Subjects

73 NUCLEAR PHYSICS AND RADIATION PHYSICS
OXYGEN 16 TARGET
PION PLUS REACTIONS
OXYGEN 18 TARGET
QUASI-FREE REACTIONS
ANGULAR CORRELATION
ANGULAR DISTRIBUTION
ANGULAR MOMENTUM
DEUTERONS
ENERGY LEVELS
MEV RANGE 100-1000
MOMENTUM TRANSFER
NITROGEN 14
NITROGEN 16
PROTONS
RECOILS
TOTAL CROSS SECTIONS
BARYONS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
CHARGED PARTICLES
CHARGED-PARTICLE REACTIONS
CORRELATIONS
CROSS SECTIONS
DIRECT REACTIONS
DISTRIBUTION
ELEMENTARY PARTICLES
ENERGY RANGE
FERMIONS
HADRON REACTIONS
HADRONS
ISOTOPES
LIGHT NUCLEI
MESON REACTIONS
MEV RANGE
NITROGEN ISOTOPES
NUCLEAR REACTIONS
NUCLEI
NUCLEONS
ODD-ODD NUCLEI
PION REACTIONS
RADIOISOTOPES
SECONDS LIVING RADIOISOTOPES
STABLE ISOTOPES
TARGETS
651320* - Nuclear Properties &amp; Reactions
A=6-19
Experimental