La138-Ce138-

Takehito Hayakawa

¹

,

T. Shizuma

²

,

Toshitaka Kajino

³

et al.

Reply to “Comment on ‘La138−Ce138−Hayakawa1, Shizuma2, Kajino3 et al. 2009Phys. Rev. CSelf Cite0000View full textAdd to dashboardCite

“…This 1 + state has energy higher than 72 keV, and should correspond to the observed 1 + state discussed below. This result indicates that there is no 1 + isomer in 138 La [1].…”

“…This 1 + state has energy higher than 72 keV, and should correspond to the observed 1 + state discussed below. This result indicates that there is no 1 + isomer in 138 La [1].The excited states on 138 La have been studied in nucleon transfer reactions of 139 La(d,t) 138 La [11] and 139 La(p,d) 138 La [12] reactions. However, the 1 + state has not been observed since the spin of the ground state of 139 La is J π = 7/2 + .…”

“…We have proposed a new nuclear cosmochronometer 138 La(T 1/2 = 102 Gyr)-138 Ce-136 Ce for measuring the time elapsed from a supernova ν process episode [1]. This chronometer is applied to evaluate the age of a presolar grain originated from a supernova by measuring isotope ratios of three p nuclei, 138 La, 138 Ce, and 136 Ce; 138 La is synthesized by the ν process in He-and C-rich layers [2,3] and 136,138 Ce are synthesized by the γ process in O/Ne layers [4][5][6][7].…”

“…This chronometer is applied to evaluate the age of a presolar grain originated from a supernova by measuring isotope ratios of three p nuclei, 138 La, 138 Ce, and 136 Ce; 138 La is synthesized by the ν process in He-and C-rich layers [2,3] and 136,138 Ce are synthesized by the γ process in O/Ne layers [4][5][6][7]. We pointed out that the nuclear structure of 138 La may affect the performance of this cosmochronometer and the ν process origin of 138 La [1]. If a 1 + excited state exists at energy lower than 72 keV that is the energy of the first excited state, the 1 + state may be a β unstable isomer and 138 La synthesized by the ν process is destroyed via the isomer.…”

New probe of M1 and E1 strengths in GDR regions

“…The neutrino process in supernovae has been suggested [1] as the mechanism for the origin of several rare isotopes of light-to-heavy elements such as 7 Li, 11 B [2], 92 Nb [3], 138 La [4], 180 Ta [5]. Copious amounts of energetic neutrinos are emitted from the proto-neutron star formed during a core-collapse supernova.…”