RESONANT ABSORPTION OF GAMMA RADIATION FROM THE Al$sup 27$(p,$gamma$)Si$sup 28$ REACTION

Journal Article · Tue Apr 15 04:00:00 EST 1958 · Physical Review (U.S.) Superseded in part by Phys. Rev. A, Phys. Rev. B: Solid State, Phys. Rev. C, and Phys. Rev. D

DOI:https://doi.org/10.1103/PhysRev.110.397· OSTI ID:4336497

Smith, P B; Endt, P M

Gamma rays emitted by excited Si/sup 28/ formed in the reaction Al/sup 27/(p, gamma )Si/sup 28/ at E/sub p/ = 771 kev have been selectively absorbed in silicon. Selective, or resonant, absorption occurs when the absorber is placed at such an angle that the loss of energy upon emission and reabsorption of the photons is restored by the Doppler shift resulting from the forward motion of the excited Si/sup 28/ nucleus. A narrow silt in a lead collimator is filled with silicon powder, and the transmitted gamma radiation is detected by a scintillation counter. The absorption dip observed as the collimator is rotated through the resonant angle has a width of 0.75 degree, the maximum absorption amounting to 21%. From the integral of the absorption as a function of angle, and from an absolute measurement of the (p,y) integral cross section, the radiation width for transition to the ground state (E/sub gamma / == 12.33 Mev) is determined to be 5.2 plus or minus 0.5 ev, while 2.0 plus or minus 0.5 ev is found for the proton width, and 9.0 plus or minus 0.8 ev for the total width. The half life calculated from the latter is (4.5 plus or minus 0.4) x 10/sup - 17/ sec. These values, together with the angular distribution of the ground- state radiation, are consistent with a 1/sup +/ assignment to the resonance level. (auth)

• Research Organization: Rijksuniversiteit, Utrecht
• NSA Number: NSA-12-010122
• OSTI ID: 4336497
• Journal Information: Physical Review (U.S.) Superseded in part by Phys. Rev. A, Phys. Rev. B: Solid State, Phys. Rev. C, and Phys. Rev. D, Journal Name: Physical Review (U.S.) Superseded in part by Phys. Rev. A, Phys. Rev. B: Solid State, Phys. Rev. C, and Phys. Rev. D Vol. Vol: 110; ISSN PHRVA
• Country of Publication: Country unknown/Code not available
• Language: English

Related Subjects

ABSORPTION
ALUMINUM 27
ANGULAR DISTRIBUTION
CROSS SECTIONS
EMISSION
ENERGY LEVELS
ENERGY RANGE
EXCITATION
GAMMA DETECTION
GAMMA RADIATION
HALF-LIFE
LEAD
LIFETIME
MEASURED VALUES
NUCLEAR REACTIONS
OPTICAL SYSTEMS
PARITY
PHOTONS
PHYSICS
PROTON BEAMS
RESONANCE
SCINTILLATION COUNTERS
SILICON 28
SPECTRAL SHIFT
SPIN
TRANSIENTS