TY - JOUR

T1 - Universality of decay-out of superdeformed bands in the 190 mass region

AU - Cardamone, D. M.

AU - Barrett, B. R.

AU - Stafford, C. A.

N1 - Funding Information:
We thank Anna Wilson, Teng Lek Khoo, Daniel Stein, Jérôme Bürki, Bertrand Giraud, and Sven Åberg for useful discussions. We thank TRIUMF and the Institute for Nuclear Theory for hospitality during the formation and completion of portions of this work. This work was partially funded by United States NSF grants PHY-0244389 and PHY-0555396. Appendix A Eq. (12) places a limit on the experimentally-determined quantities. Positivity of Γ ↓ requires that (A.1) Γ N > Γ out . In only two decays of Table 1 , 192 Pb(10) and 152 Dy(26), is this condition violated. While it is possible that this is due to a breakdown of the two-level approximation in these cases, in the absence of a physical argument for the near degeneracy of two or more ND levels, it is more likely that one or more of the input parameters is poorly known. Γ N , in particular, is difficult to estimate, with uncertainty σ Γ N ∼ Γ N . Thus, we estimate Γ ↓ statistically for these two decays, assuming the true Γ N differs from the estimated value Γ N 0 by a “cut” normal distribution: (A.2) P ( Γ N ) = { A Γ N 0 2 π e − ( Γ N − Γ N 0 2 Γ N 0 ) 2 , Γ N > Γ out , 0 , otherwise , where the constant of renormalization due to the constraint is (A.3) A = 2 { erfc [ 1 2 ( Γ out Γ N 0 − 1 ) ] } −1 . Assuming that the two-level approximation is valid, the probability density function of Γ ↓ follows: (A.4) P ( Γ ↓ ) = P ( Γ N ) | d Γ N d Γ ↓ | = ( Γ N Γ ↓ ) 2 P ( Γ N ) , where Γ ↓ is the function of Γ N given by Eq. (12) . For 192 Pb(10) and 152 Dy(26), Table 1 gives the median of this distribution as the typical value of Γ ↓ , from which ⟨ V ⟩ is found.

PY - 2008/3/20

Y1 - 2008/3/20

N2 - Superdeformed nuclei in the 190 mass region exhibit a striking universality in their decay-out profiles. We show that this universality can be explained in the two-level model of superdeformed decay as related to the strong separation of energy scales: a higher scale related to the nuclear interactions, and a lower scale caused by electromagnetic decay. Decay-out can only occur when separate conditions in both energy regimes are satisfied, strongly limiting the collective degrees of freedom available to the decaying nucleus. Furthermore, we present the results of the two-level model for all decays for which sufficient data are known, including statistical extraction of the matrix element for tunneling through the potential barrier.

AB - Superdeformed nuclei in the 190 mass region exhibit a striking universality in their decay-out profiles. We show that this universality can be explained in the two-level model of superdeformed decay as related to the strong separation of energy scales: a higher scale related to the nuclear interactions, and a lower scale caused by electromagnetic decay. Decay-out can only occur when separate conditions in both energy regimes are satisfied, strongly limiting the collective degrees of freedom available to the decaying nucleus. Furthermore, we present the results of the two-level model for all decays for which sufficient data are known, including statistical extraction of the matrix element for tunneling through the potential barrier.

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U2 - 10.1016/j.physletb.2008.01.064

DO - 10.1016/j.physletb.2008.01.064

M3 - Article

AN - SCOPUS:39949083203

SN - 0370-2693

VL - 661

SP - 233

EP - 238

JO - Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics

JF - Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics

IS - 2-3

ER -