Coulomb excitation of radioactive 20, 21Na
Tóm tắt
The low-energy structures of the radioactive nuclei 20, 21Na have been examined using Coulomb excitation at the TRIUMF-ISAC radioactive ion beam facility. Beams of ∼ 5×106 ions/s were accelerated to 1.7MeV/A and Coulomb excited in a 0.5mg/cm^2 natTi target. Two TIGRESS HPGe clover detectors perpendicular to the beam axis were used for
$ \gamma$
-ray detection, while scattered nuclei were observed by the Si detector BAMBINO. For 21Na , Coulomb excitation from the 3/2+ ground state to the first excited 5/2+ state was observed, while for 20Na , Coulomb excitation was observed from the 2+ ground state to the first excited 3+ and 4+ states. For both beams, B (
$ \lambda$
L) values were determined using the 2+
$ \rightarrow$
0+ de-excitation in 48Ti as a reference. The resulting B(E2) ↓ value for 21Na is 137±9 e^2fm^4, while the resulting B(
$ \lambda$
L) ↓ values for 20Na are 55±6 e^2fm^4 for the 3+
$ \rightarrow$
2+ , 35.7±5.7 e^2 fm^4 for the 4+
$ \rightarrow$
2+ , and 0.154±0.030 μ_N^2 for the 4+
$ \rightarrow$
3+ transitions. This analysis significantly improves the measurement of the 21Na B(E2) value, and provides the first experimental determination of B(
$ \lambda$
L) values for the proton dripline nucleus 20Na .-1
Tài liệu tham khảo
R.B. Firestone, Nucl. Data Sheets 103, 269 (2004) with Oct. 16, 2006 National Nuclear Data Center (NNDC) online errata.
D. Seweryniak et al., Phys. Lett. B 590, 170 (2004).
P.M. Rowe et al., J. Phys. G 4, 431 (1978).
A. Anttila, M. Bister, Phys. Lett. B 29, 645 (1969).
A. Anttila, M. Bister, J. Keinonen, Z. Phys. A 274, 227 (1975).
J.G. Pronko, R.A. Lindgren, D.A. Bromley, Nucl. Phys. A 140, 465 (1970).
R.E. Laxdal, Nucl. Instrum. Methods B 204, 400 (2003).
C.E. Svensson et al., Nucl. Instrum. Methods A 540, 348 (2005).
H.C. Scraggs et al., Nucl. Instrum. Methods A 543, 431 (2005).
C.E. Svensson et al., J. Phys. G: Nucl. Part. Phys. 31, S1663 (2005).
M.A. Schumaker et al., Nucl. Instrum. Methods A 570, 437 (2007).
M.A. Schumaker et al., Nucl. Instrum. Methods A 573, 157 (2007).
M.A. Schumaker, C.E. Svensson, Nucl. Instrum. Methods A 575, 421 (2007).
M.A. Schumaker et al., Phys. Rev. C 78, 044321 (2008).
M.A. Schumaker et al., submitted to Phys. Rev. C.
A.M. Hurst et al., Phys. Lett. B 674, 168 (2009).
C.E. Svensson et al., Nucl. Instrum. Methods B 204, 660 (2003).
J.-P. Martin, C. Mercier, N. Starinski, C.J. Pearson, P.-A. Amaudruz, IEEE Trans. Nucl. Sci. 55, 84 (2008).
K. Alder, A. Winther, Electromagnetic Excitation} (North-Holland, Amsterdam, 1975).
D. Cline, H.S. Gertzman, H.E. Gove, P.M.S. Lesser, J.J. Schwartz, Nucl. Phys. A 133, 445 (1969).
T.W. Burrows, Nucl. Data Sheets 107, 1747 (2006).
J.F. Ziegler, J.P. Biersack, M.D. Ziegler, http://www.srim.org.
T. Czosnyka, D. Cline, C.Y. Wu, Bull. Am. Phys. Soc. 28, 745 (1983).
K. Krane, Nucl. Instrum. Methods 98, 205 (1972).
S. Agostinelli et al., Nucl. Instrum. Methods A 506, 250 (2003).
D. Cline, Annu. Rev. Nucl. Part. Sci. 36, 683 (1986).
L.D. Tolsma, Phys. Rev. C 20, 592 (1979).
J. Stachel, N. Kaffrell, E. Grosse, H. Emling, H. Folger, R. Kulessa, D. Schwalm, Nucl. Phys. A 383, 429 (1982).
D.J. Millener, private communication, 1984; B.H. Wildenthal, Prog. Part. Nucl. Phys. 11, 5 (1984).
B.A. Brown, A. Etchegoyen, N.S. Godwin, W.D.M. Rae, W.A. Richter, W.E. Ormand, E.K. Warburton, J.S. Winfield, L. Zhao, C.H. Zimmerman, Oxbash for Windows, MSU-NSCL report number 1289.
B.A. Brown, W.A. Richter, Phys. Rev. C 74, 034315 (2006).