| Summary: | This work embraces the measurement of angular distributions and excitation functions
for proton radiative capture to the ground and excited states of 13N, in energy steps from
E p = 40 to E p = 52MeV.
Legendre polynomial fits to the angular distributions are made and the energy variation
of Legendre coefficients is established for several (p, 7 ) transitions involving states
up to an excitation energy of 15 MeV. The polynomial coefficients are explained by large
dipole-quadrupole interference effects, particularly interesting at excitation energies corresponding
to twice (£„ ~ 46 MeV) the centroid value of the ground state based Giant
Dipole Excitation. Broad resonances are found in the (p,7o) &nd the (p, 72+3) channels,
which involve final states that are members of the same rotational band and therefore
should present very similar internal structures as the almost equivalent Legendre coefficients
substantiate. For other excited states similar trends have been found although
within limits imposed by larger experimental errors.
The 2hw -+ Ihuj transition is found largely superimposed on inelastic proton scattering
channels, contrary to what was established in previous experiments. Upper limits for the
excitation functions are extracted and only for the highest measured energy point are the
two contributions clearly separated.
This reasearch program is based on a newly-developed anti-coincidence large-volume
scintillation spectrometer designed by means of a Monte Carlo simulation code. Sp jcific
tests performed with Tandem accelerator beams, and routine application at higher energies,
demonstrate the excellent correspondence of the design expectations with the performance
as measured, for this spectrometer.
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