Experimental study of radiative pion capture on /sup 13/C, /sup 20/Ne, /sup 90/Zr, /sup 19/F and /sup 12/C

Technical Report · Sat Nov 01 04:00:00 EST 1980

DOI:https://doi.org/10.2172/6704959· OSTI ID:6704959

Martoff, C J

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: California Univ., Berkeley (USA). Lawrence Berkeley Lab.
• DOE Contract Number: W-7405-ENG-48
• OSTI ID: 6704959
• Report Number(s): LBL-10954
• Country of Publication: United States
• Language: English

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73 NUCLEAR PHYSICS AND RADIATION PHYSICS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BORON 12
BORON 13
BORON ISOTOPES
BRANCHING RATIO
CAPTURE
CARBON 12 TARGET
CARBON 13 TARGET
CHARGED-PARTICLE REACTIONS
CROSS SECTIONS
DATA
DAYS LIVING RADIOISOTOPES
ELECTROMAGNETIC RADIATION
ENERGY RANGE
EVEN-ODD NUCLEI
EXPERIMENTAL DATA
FLUORINE 19 TARGET
FLUORINE 20
FLUORINE ISOTOPES
GAMMA RADIATION
GAMMA SPECTRA
GAMOW-TELLER RULES
HADRON REACTIONS
HOURS LIVING RADIOISOTOPES
INFORMATION
INTERMEDIATE MASS NUCLEI
IONIZING RADIATIONS
ISOMERIC TRANSITION ISOTOPES
ISOTOPES
KINETICS
LIGHT NUCLEI
MATHEMATICAL MODELS
MESON REACTIONS
MEV RANGE
MEV RANGE 10-100
NEON 20 TARGET
NUCLEAR MODELS
NUCLEAR REACTION KINETICS
NUCLEAR REACTIONS
NUCLEI
NUMERICAL DATA
ODD-EVEN NUCLEI
ODD-ODD NUCLEI
OXYGEN 19
OXYGEN ISOTOPES
PION MINUS REACTIONS
PION REACTIONS
RADIATIONS
RADIOISOTOPES
REACTION KINETICS
SECONDS LIVING RADIOISOTOPES
SHELL MODELS
SPECTRA
TARGETS
YTTRIUM 90
YTTRIUM ISOTOPES
ZIRCONIUM 90 TARGET