Directionality of Solar Flare Accelerated Protons and Alpha Particles from Gamma-Ray Line Measurements

The energies and widths of gamma-ray lines emitted by ambient nuclei excited by flare-accelerated protons and alpha particles provide information on the ions directionality and spectra, and on the characteristics of the interaction region. We have measured the energies and widths of strong lines from de-excitations of 12C, 16O, and 20Ne in solar flares as a function of heliocentric angle. The line energies from all three nuclei exhibit ~1% redshifts for flares at small heliocentric angles, but are not shifted near the limb. The lines have widths of ~3% FWHM. We compare the 12C line measurements for flares at five different heliocentric angles with calculations for different interacting-particle distributions. A downward isotropic distribution (or one with a small upward component) provides a good fit to the line measurements. An angular distribution derived for particles that undergo significant pitch angle scattering by MHD turbulence in coronal magnetic loops provides comparably good fits

Rapid onset of collectivity in the vicinity of 78Ni

gamma-rays following the B and B-n decay of the very neutron rich 84Ga produced by photo-fission of 238U have been studied at the newly built ISOL facility of IPN Orsay: ALTO. Two activities were observed and assigned to two B-decaying states: 84gGa, I = (0\^-) and 84mGa, I = (3\^-, 4\^-). Excitation energies of the 2+1 and 4+1 excited states of 84Ge were measured at E(2+1) = 624.3 keV and E(4+1) = 1670.1 keV. Comparison with HFB+GCM calculations allows to establish the collective character of this nucleus indicating a substantial N=50 core polarization. The excitation energy of the 1/2+1 state in 83Ga known to carry a large part of the neutron 3s1/2 strength was measured at 247.8keV. Altogether these data allow to confirm the new single particle state ordering which appears immediately after the double Z=28 and N=50 shell closure and to designate 78Ni as a fragile and easily polarized doubly-magic core.Comment: 4 pages, ReVTe

Etude de la réaction 18F (p, alpha) 15O par réaction de transfert pour application à l'émission gamma des Novæ

PARIS7-Bibliothèque centrale (751132105) / SudocSudocFranceF

Etude de la réaction 18F (p, alpha) 15O par réaction de transfert pour application à l'émission gamma des Novæ

PARIS7-Bibliothèque centrale (751132105) / SudocSudocFranceF

Semiempirical breakdown curves of C2_2N(+)^{(+)} and C3_3N(+)^{(+)}molecules; application to products branching ratios predictions of physical and chemical processes involving these adducts

We constructed semiempirical breakdown curves (BDC) for C$_2$N, C$_3$N, C$_2$N$^+$ and C$_3$N$^+$ molecules. These BDC, which are energy dependent dissociation branching ratios (BR) curves, were used to predict products branching ratios for various processes leading to the formation of C$_2$N$^{(+)}$ and C$_3$N$^{(+)}$ excited adducts. These processes, of astrochemical interest, are neutral-neutral and ion-molecule reactions, dissociative recombination and charge transfer reactions with He$^+$. Model predictions of BR are compared to the literature data and to reported values in the kinetic database for astrochemistry KIDA. With the new BR values, the C$_n$N abundances in cold cores were simulated

rapid onset of collectivity in the vicinity of 78Ni

4 pages, ReVTeXgamma-rays following the β and β-n decay of the very neutron rich 84Ga produced by photo-fission of 238U have been studied at the newly built ISOL facility of IPN Orsay: ALTO. Two activities were observed and assigned to two β-decaying states: 84gGa, I = (0−) and 84mGa, I= (3−,4−). Excitation energies of the 2+1 and 4+1 excited states of 84Ge were measured at E(2+1 ) = 624.3 keV and E(4+1 ) = 1670.1 keV. Comparison with HFB+GCM calculations allows to establish the collective character of this nucleus indicating a substantial N=50 core polarization. The excitation energy of the 1/2+1 state in 83Ga known to carry a large part of the neutron 3s1/2 strength was measured at 247.8keV. Altogether these data allow to confirm the new single particle state ordering which appears immediately after the double Z=28 and N=50 shell closure and to designate 78Ni as a fragile and easily polarized doubly-magic core