Electron scattering from excited states inN14andBe

Phenomenological wave functions for the massA=14 system and a consistent description of beta decay observables

“…The restricted amplitude range was used in a second step to find the third independent amplitude ~ which represents the main components of the T = 1 triplet states. For this purpose the magnetic dipole strength B (M1, q, T= 1) of the first excited state in 14N which has been measured in four (e,e') experiments [12,22,23,25] as well as the shape factors of the isospin analogue beta decays [26,27] in 14C and 140 were fitted by the above given formulae. For the magnetic dipole strength, too, only data with q2=< 5 fm -2 were taken into account since data above that point obviously can not be reproduced within the model space employed here.…”

“…The wave functions result from a simultaneous fit to the elastic and the inelastic electron scattering form factor of 14N, the static magnetic moment of the 14N ground state, and the shape factor of the 14C and 140 /?-decay, respectively. It is thus emphasized again that as compared to former work on the derivation of phenomenological wave function in the A = 14 system [3,12,17,24] we include for the first time the experimental values of the shape factor and the new low q inelastic M1 form factor measurements performed at the DALINAC [25]. The so obtained "best fit" of wave functions could then be tested in other processes in the A = 14 system like elastic and inelastic hadron scattering, charge exchange reactions with hadrons and mesons, radiative muon and pion capture and photo pion reactions.…”

“…Shell model configuration amplitudes have been deduced phenomenologically from the data on the magnetic dipole form factors for the 14N ground state and for the transition to the 2.313 MeV, 0 + level [12,[22][23][24]. However, the wave functions obtained by this method do partly not describe satisfactorily the ft +-values, which are in some cases orders of magnitude larger than predicted.…”

“…decay is due to a nearly complete cancellation among terms in the/?-decay matrix elements from the usual impulse approximation contributions and from normally negligible processes, such as meson exchange currents, core polarization or relativistic effects [15][16][17]. A number of wave functions derived from microscopic treatments have been proposed which satisfy some of these requirements and also describe consistently observables like the static magnetic moment of the ground state of 14N or the low momentum transfer properties in the A = 14 system [2- 5,12,13,[18][19][20][21] in general. However, there does not exist a set of wave functions that predicts correctly all measured observables.…”

14N Nuclear Quadrupole Coupling — Correlation of Experimental and Theoretical Values with Structure

“…Fundamental to these studies is a value for the nitrogen atom quadrupole coupling constant {Qu)\ this is not readily obtained by electronic or micro wave spectroscopy, except as the product qaQu, however, two relatively recent values have been ob tained from scattering experiments; electron scatter ing yields the value 17.4 ± 0.2 mbarn [4], which is in excellent agreement with both a least squares fit of the data above [2], which yields 17.2 mbarn, and with other theoretical estimates based on small numbers of compounds [5]. However, fast-ion bom bardment has yielded 19.3 ± 0.8 mbarn [6] (closer to [5 c] than other calculated values), and the error bounds from [5, 6] do not overlap, and clearly do not lead to an agreed experimental value.…”