Experimental study of radiative pion capture on /sup 13/C, /sup 20/Ne, /sup 90/Zr, /sup 19/F and /sup 12/C
Photon spectra for 50 < E/sub ..gamma../ < 135 MeV have been measured from the radiative capture of stopped negative pions by the nuclides /sup 13/C, /sup 19/F, /sup 20/Ne, and /sup 90/Zr. The e/sup +/e/sup -/ pair spectrometer system used has resolution 850 keV fwhm and photon detection efficiency 5 x 10/sup -6/. The total radiative capture branching ratios measured are /sup 13/C (1.66 +- 0.25)%, /sup 19/F (2.40 +- 0.48)%, /sup 20/Ne (1.60 +- 0.24)%, and /sup 90/Zr (2.1 +- 0.5)%. The partial radiative capture branching ratios to four bound states and two resonances in /sup 20/F, and two bound states and three resonances in /sup 13/B have also been measured. The branching ratio for /sup 13/C(..pi../sup -/,..gamma..)/sup 13/B g.s. is (6.1 +- 1.2) x 10/sup -4/. Comparison of this result with the beta decay rate of /sup 13/B shows that (84 +- 16)% of the pion capture amplitude is accounted for by the Gamow-Teller matrix element. Further analysis suggests that much of the remaining strength is E2. The measured branching ratios to resonant states in /sup 13/C(..pi../sup -/,..gamma..)/sup 13/B are shown to be in agreement with detailed shell model calculations. The total single-particle strength in these transitions is shown to be approximately half as large as that of the T = 3/2 part of the E1 photoresonance (the Giant Dipole Resonance) in /sup 13/C. The branching ratio for /sup 20/Ne(..pi../sup -/,..gamma..)/sup 20/F (T = 1, J/sup ..pi../ = 1/sup +/, E/sub x/ = 1.06 MeV) is 0.91 +- 0.52).10/sup -4/. Comparison with the electroexcitation of the analog giant M1 state in /sup 20/Ne (11.24 MeV) shows that the M1 transition amplitude is less than (46 +- 14)% Gamow-Teller. This result is in agreement with detailed shell model calculations of the M1 transition. The photon spectrum for radiative pion capture from flight (reaction /sup 12/C(..pi../sup +/ T = 44 MeV, ..gamma.. at 90/sup 0/)) has been measured. 13 figures, 12 tables.
- Research Organization:
- Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 6704959
- Report Number(s):
- LBL-10954; TRN: 81-002792
- Resource Relation:
- Other Information: Thesis
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
PION MINUS REACTIONS
CAPTURE
CARBON 13 TARGET
FLUORINE 19 TARGET
NEON 20 TARGET
ZIRCONIUM 90 TARGET
CARBON 12 TARGET
BRANCHING RATIO
EXPERIMENTAL DATA
GAMMA RADIATION
GAMMA SPECTRA
GAMOW-TELLER RULES
NUCLEAR REACTION KINETICS
SHELL MODELS
BORON 13
FLUORINE 20
OXYGEN 19
YTTRIUM 90
BORON 12
CROSS SECTIONS
MEV RANGE 10-100
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BORON ISOTOPES
CHARGED-PARTICLE REACTIONS
DATA
DAYS LIVING RADIOISOTOPES
ELECTROMAGNETIC RADIATION
ENERGY RANGE
EVEN-ODD NUCLEI
FLUORINE ISOTOPES
HADRON REACTIONS
HOURS LIVING RADIOISOTOPES
INFORMATION
INTERMEDIATE MASS NUCLEI
IONIZING RADIATIONS
ISOMERIC TRANSITION ISOTOPES
ISOTOPES
KINETICS
LIGHT NUCLEI
MATHEMATICAL MODELS
MESON REACTIONS
MEV RANGE
NUCLEAR MODELS
NUCLEAR REACTIONS
NUCLEI
NUMERICAL DATA
ODD-EVEN NUCLEI
ODD-ODD NUCLEI
OXYGEN ISOTOPES
PION REACTIONS
RADIATIONS
RADIOISOTOPES
REACTION KINETICS
SECONDS LIVING RADIOISOTOPES
SPECTRA
TARGETS
YTTRIUM ISOTOPES
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