ENERGY AND ANGULAR DISTRIBUTIONS OF PHOTO-PROTONS FROM NITROGEN-15. Technical Report No. 3
Nitrogen gas, enriched 95.7% in N/sup 15/, was exposed to betatron bremsstrahlung of 18.7 and 24.6 Mev maximum energy, and the photoprotons resulting from the reaction N/sup 15/( ,p)C/sup 14/ were detected in nuclear emulsions. The energy and angular distributions of the protons were determimed as were the photoproton yield and cross section. The yield with 18.7 Mev bremsstrahlung was 2.06 ( plus or minus 0.3) x 10/sup 4/ protons/atomic weight/ roentgen, while the yield with 24.6 Mev bremsstrahlung was 1.06 ( plus or minus 0.14) x 10/sup 5/ protons/ atomic weight/roentgen. The integrated cross section from threshold up to 24.6 Mev for photoprotons in which the residual nucleus is left in its ground state was 14.5 ( plus or minus 1.5) Mev-mb, while the integrated cross section over the same energy range for transitions in which the residual nucleus is left in excited states was 24 ( plus or minus 5) Mev-mb, giving a total photoproton cross section over this energy interval of 35 ( plus or minus 5) Mev-mb. In addition to the gian resonance'' extending from 19 to 24 Mev with integrated cross section equal to 10.3 Mev-mb the cross section vs. photon energy curve for ground state transitions shows small peaks at 11.6 Mev, at 15 Mev, and at 18.6 Mev, with integrated cross sections of 0.80, 1.47, and 0.75 Mev-mb, respectively. A narrow peak at 20.5 Mev in the giant resonance'' region has an integrated cross section of about 0.5 Mev-mb. The angular distributions of the various proton groups fit curves of the form A + sin/sup 2/ theta (1 + method of ga cos theta )/sup 2/. The asymmetry coefficient is approximately equal to 0.3. For protons of energy less than 9 Mev, the ratio A/B is found to be consistent with calculated distributions of protons emitted from isolated energy levels in the target nucleus. For protons of energy greater than 9 Mev a predominantly sin/sup 2/ theta distribution was found; the reduced isotropic component observed in the angular distribution of these protons is attributed to interference in s-wave and d-wave protons emitted from overlapping states accessible by electric dipole absorption in N/sup 15/. (auth)
- Research Organization:
- Pennsylvania. Univ., Philadelphia
- NSA Number:
- NSA-12-006874
- OSTI ID:
- 4308235
- Report Number(s):
- NP-6624
- Country of Publication:
- United States
- Language:
- English
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ANGULAR DISTRIBUTION
BETATRONS
BREMSSTRAHLUNG
CARBON 14
CROSS SECTIONS
D-WAVE
DETECTION
DIPOLES
DISTRIBUTION
EFFICIENCY
ELECTRIC MOMENTS
ELEMENTARY PARTICLES
ENERGY
ENERGY LEVELS
ENERGY RANGE
ENRICHMENT
GAMMA RADIATION
GIANT RESONANCE
MEASURED VALUES
NITROGEN 15
NUCLEAR EMULSIONS
NUCLEAR REACTIONS
PHOTONS
PHOTOPRODUCTION
PHYSICS
PROTONS
QUANTUM MECHANICS
RADIATION DOSES
RESONANCE
S-WAVE
SCATTERING
SPECTRA
TARGETS
TRANSIENTS