β-decay half-lives and β-delayed neutron multiplicities of the neutron drip-line nuclei 19 B, 22 C, and 23 N

Beta-decay properties of the neutron drip-line nuclei ${}^{19}\mathrm{B},{}^{22}\mathrm{C},$ and ${}^{23}\mathrm{N}$ have been studied using projectile fragments from 95 MeV/nucleon ${}^{40}\mathrm{Ar}$ ions incident on a ${}^{\mathrm{nat}}\mathrm{Ta}$ target. The $\ensuremath{\beta}$-decay half-lives of ${}^{22}\mathrm{C}$ and ${}^{23}\mathrm{N}$ have been determined for the first time to be ${6.1}_{\ensuremath{-}1.2}^{+1.4}$ and ${14.1}_{\ensuremath{-}1.5}^{+1.2}$ ms, respectively. The half-life of ${}^{19}\mathrm{B}$ was reinvestigated, resulting in a new value of $2.92\ifmmode\pm\else\textpm\fi{}0.13$ ms. The $\ensuremath{\beta}$-delayed neutron multiplicities have also been determined to be ${P}_{1n}{=71.8}_{\ensuremath{-}9.1}^{+8.3}%,{P}_{2n}{=16.0}_{\ensuremath{-}4.8}^{+5.6}%$ for ${}^{19}\mathrm{B},{P}_{1n}{=61}_{\ensuremath{-}13}^{+14}%$ for ${}^{22}\mathrm{C},$ and ${P}_{1n}{=42.2}_{\ensuremath{-}6.5}^{+6.3}%,{P}_{2n}{=8.0}_{\ensuremath{-}3.4}^{+3.8}%$ for ${}^{23}\mathrm{N}.$ The results are compared with theoretical predictions.

[1]  A. Yoshida,et al.  New neutron-rich isotopes, 34Ne, 37Na and 43Si, produced by fragmentation of a 64 A MeV 48Ca beam , 2002 .

[2]  R. G. Allatt,et al.  Radioactivity of neutron-rich oxygen, fluorine, and neon isotopes , 1999 .

[3]  Yusuke Watanabe,et al.  Evidence for particle stability of 31 F and particle instability of 25 N and 28 O , 1999 .

[4]  S. Yamamoto,et al.  Half-life measurements of the neutron drip line nuclei , and , 1998 .

[5]  T. Tachibana,et al.  Semi-gross theory of nuclear β-decay , 1997 .

[6]  A. H. Wapstra,et al.  The N evaluation of nuclear and decay properties , 1997 .

[7]  T. Nakamura,et al.  Search for new neutron-rich nuclei with a 70A MeV 48Ca beam , 1997 .

[8]  A. H. Wapstra,et al.  The 1995 update to the atomic mass evaluation , 1995 .

[9]  H. Klein,et al.  A modular 4p counter for -delayed neutrons , 1995 .

[10]  Isao Tanihata,et al.  The RIKEN radioactive beam facility , 1992 .

[11]  B. Sherrill,et al.  INTENSITY: a computer program for the estimation of secondary beam intensities from a projectile fragment separator , 1992 .

[12]  Brown,et al.  beta -decay branching ratios of the neutron-rich nucleus 15B. , 1991, Physical review. C, Nuclear physics.

[13]  H. Klapdor-kleingrothaus,et al.  Measurement and QRPA calculation of the β-delayed neutron emission of 21,22N and 23,24O , 1990 .

[14]  H. Klapdor-kleingrothaus,et al.  Second-generation microscopic predictions of beta-decay half-lives of neutron-rich nuclei , 1990 .

[15]  A. Richard,et al.  β-Delayed neutron emission of the isotopes 20C, 40,41,42P, 43,44S☆ , 1989 .

[16]  H. Grawe,et al.  A 2π neutron multiplicity filter for in-beam γ-ray spectroscopy of neutron deficient nuclei , 1988 .

[17]  K. Takahashi,et al.  A New Semiempirical Shell Correction to the Droplet Model , 1976 .