Improving systematic predictions of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>β</mml:mi></mml:math>-delayed neutron emission probabilities

McCutchan, E. A.; Sonzogni, A. A.; Johnson, Timothy D.; Abriola, D.; Birch, M.; Singh, Balraj

doi:10.1103/physrevc.86.041305

Cited by 40 publications

(56 citation statements)

References 29 publications

(31 reference statements)

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“…This is in qualitative agreement with GFMC calculations using AV18 plus IL7 [22]. Furthermore, the B(E2) from the first 2 + to the ground state is strong, around 6 to 8 e 2 fm 4 in our calculations, whereas that of the second 2 + is weak, of the order of 0.1 e 2 fm 4 in our calculations.…”

Section: Results Forsupporting

confidence: 80%

Ab initio calculations for Be-isotopes with JISP16

Maris

2013

J. Phys.: Conf. Ser.

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Abstract. We present recent results from no-core configuration interaction calculations for 8 Be,10 Be, and 12 Be using the phenomenological two-body interaction JISP16. We calculate the binding energies of the ground state and the excitation energies of the low-lying positiveparity states. We discuss the contributions from the proton and neutron intrinsic spin and orbital motion to the total spin for several states, and use this to identify states which may be dominated by α-cluster configurations. In addition, we also calculate other observables such as dipole and quadrupole moments, as well as transition rates for select E2 transitions. No-Core Configuration Interaction approachConfiguration Interaction (CI) methods have been used in recent years to make increasingly accurate large scale ab initio calculations in nuclear structure, see e.g. Refs. [1, 2] and references therein. In this method, the many-body Schrödinger equationbecomes a large sparse matrix problem with eigenvalues E i . Improved algorithms to construct this matrix and to determine its lowest eigenstates, as well as efficient use of increasing computational resources are critical for these successes [3,4,5,6,7,8].In the No-Core CI (NCCI) approach [1, 2, 9] the wavefunction Ψ of a nucleus consisting of A nucleons (protons and neutrons) is expanded in an A-body basis of Slater determinants Φ k of single-particle wavefunctions φ nljm ( r)and A the antisymmetrization operation. Conventionally, one uses a harmonic oscillator (HO) basis for the singleparticle wavefunctions, but it is straightforward to extend this approach to a more general single-particle basis [10]. The single-particle wavefunctions are labelled by the quantum numbers n, l, j, and m, where n and l are the radial and orbital HO quantum numbers, with N i = 2n i + l i the number of HO quanta; j is the total single-particle spin, and m its projection along the z-axis. The many-body basis states Φ k have well-defined total spin-projection, which is simply the sum of m i of the single-particle states, M = m i (hence the name M -scheme), but they do not have a well-defined total spin J. Some of the benefits of this scheme is that it is straightforward to implement, and that in two runs (one for positive and one for negative parity), we get the complete low-lying spectrum, including the ground state, even if the spin of the ground state is not known a priori.

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Section: Results Forsupporting

confidence: 80%

Ab initio calculations for Be-isotopes with JISP16

Maris

2013

J. Phys.: Conf. Ser.

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“…THEORETICAL CALCULATIONS Figure 9 presents a comparison of the 93 Br half-life and β-delayed neutron branching ratio from this experiment with the previously reported value [7], the various theoretical calculations: modified Gross Theory [40], FRDM+QRPA [41,42], DF3a+CQRPA [43], and systematics [44]. Although none of the models can predict the observed values, the new experimental point seems to fit an expected systematic trend in the correlation between P n and T 1/2 seen in the theoretical calculations.…”

Section: Comparison Of Results Withmentioning

confidence: 96%

β-decay study of neutron-rich bromine and krypton isotopes

Miernik¹,

Rykaczewski²,

Grzywacz³

et al. 2013

Phys. Rev. C

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“…In previous calculations [1,17,30] of nuclei in the A = 6-10 range, we have found that E2 matrix elements of narrow states are generally quite stable under GFMC propagation, and seldom vary much from the initial VMC estimate. However, matrix elements from wide states, e.g., for the 6 Li (2 + ; 0) → (0 + ; 0) decay, show a significant evolution as a function of τ .…”

Section: Electromagnetic Transitions Inmentioning

confidence: 99%

Quantum Monte Carlo calculations of electromagnetic transitions inBe8with meson-exchange currents derived from chiral effective field theory

et al. 2014

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We report quantum Monte Carlo calculations of electromagnetic transitions in 8 Be. The realistic Argonne v18 two-nucleon and Illinois-7 three-nucleon potentials are used to generate the ground state and nine excited states, with energies that are in excellent agreement with experiment. A dozen M 1 and eight E2 transition matrix elements between these states are then evaluated. The E2 matrix elements are computed only in impulse approximation, with those transitions from broad resonant states requiring special treatment. The M 1 matrix elements include two-body meson-exchange currents derived from chiral effective field theory, which typically contribute 20-30% of the total expectation value. Many of the transitions are between isospin-mixed states; the calculations are performed for isospin-pure states and then combined with empirical mixing coefficients to compare to experiment. Alternate mixings are also explored. In general, we find that transitions between states that have the same dominant spatial symmetry are in reasonable agreement with experiment, but those transitions between different spatial symmetries are often underpredicted.

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Improving systematic predictions ofβ-delayed neutron emission probabilities

Cited by 40 publications

References 29 publications

Ab initio calculations for Be-isotopes with JISP16

Ab initio calculations for Be-isotopes with JISP16

β-decay study of neutron-rich bromine and krypton isotopes

Quantum Monte Carlo calculations of electromagnetic transitions inBe8with meson-exchange currents derived from chiral effective field theory

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