A study of the 16O(p, pα)12C and the 20Ne(p, pα)16O reactions at 46.8 MeV

Cross sections for production of the 15.10-MeV and other astrophysically significant gamma-ray lines through excitation and spallation ofC12andLang1, Werntz2, Crannell3 et al. 1987Phys. Rev. C

“…The distribution function with respect to angle e~ and Doppler shift E~ in the laboratory frame is defined through the relation (12) The photon energy E' and angle e~ are expressed in terms of the same quantities in the center of momentum frame through the standard equations (13) and (14) Here f3em is the speed of the center of momentum frame, "' Ie = 1/VI -f3~m' cos(e'Y) = ~em• k'Y' and E~ is the laboratory Doppler shift. For small f3em (the case encountered in this experiment), "' Ie = 1, e' Y = e~, and ~n'Y = ~n~, so that, to lowest order in f3em, (15) Then it follows that the laboratory distribution function N(e~,E~) can be determined to a good approximation from the center of momentum distribution function through the relationship (16) I1LB. 160(p,X 'Y4.43S) 12 C line shape Both the 4.438-and the IS.1O-MeV line of 12C were produced by proton interactions in the BeO target.…”

“…It must be stressed that the ratios of gamma-ray production cross sections from analogue states can depart widely from the ratio O'pp/O'pn because the gamma-ray cascades "feeding" the pair of states in question may differ radically. For example, for I-GeV incident protons, Goryachev et al 25 report a ratio of about two for <T[ 160(p,2p "Y6.322) 15 N]/<T[ 160(p,X "Y6.175) 15 0], while the ratio <Tpp/<Tpn is 1.2. The reason is that there are significant cascades to the 15N(312-, 6.324) state which originate from analogue states that are unbound against particle decay in 15 0 but that are bound in 15N.…”

“…For excitation energies above 16 MeV, detailed information about particle widths of states is not available. Above 15.5 MeV the 160(p,p'a)12C*(4.439) experiment of Epstein et al 15 allows the identification of states which decay significantly through the 12C*(4.439) + al channel, but a quantitative knowledge of f al(EN)1 ftot(E N ) is still missing. Without exception, these states can be correlated with strong peaks in the Buenerd et al 16 spectrum, at least up to values of EN of about 25.5 MeV, at which energy the spectrum becomes smooth.…”

Shape of the 4.438 MeVγ-ray line of12Cfrom proton andα-particle induced reactions onKiener1, Séréville2, Tatischeff3 2001Phys. Rev. C253510View full textAdd to dashboardCite

“…The γ-ray line at 4.438 MeV from the deexcitation of the first excited state of 12 C is one of the strongest nuclear lines, clearly visible in several energetic solar flares, which were observed in particular by the Gamma Ray Spectrometer aboard the SMM satellite [1] and one of the best candidates for an observation at γ-ray energies of the interaction of low energy cosmic rays in nearby molecular clouds [2]. It is mainly produced by inelastic scattering of energetic protons and α-particles off 12 C and by the spallation of 16 O by the same particles [3]. This line is also produced in reverse kinematics by accelerated 12 C and 16 O bombarding the ambient hydrogen and helium nuclei, with however a large Doppler broadening due to the high velocities of the emitting 12 C nucleus, which makes its detection much more difficult.…”

“…It is mainly produced by inelastic scattering of energetic protons and α-particles off 12 C and by the spallation of 16 O by the same particles [3]. This line is also produced in reverse kinematics by accelerated 12 C and 16 O bombarding the ambient hydrogen and helium nuclei, with however a large Doppler broadening due to the high velocities of the emitting 12 C nucleus, which makes its detection much more difficult. In the following we will refer to γ-ray lines produced by light ion bombardment of the ambient gas as the narrow component and to γ-rays produced by accelerated heavy ions as the broad component.…”