Study of the β-delayed neutron decay of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mmultiscripts><mml:mrow><mml:mi mathvariant="normal">N</mml:mi></mml:mrow><mml:mprescripts /><mml:mrow /><mml:mrow><mml:mn>18</mml:mn></mml:mrow><mml:mrow /><mml:mrow /></mml:mmultiscripts></mml:mrow></mml:math>

Scheller, K.; Görres, J.; Ross, J. G.; Wiescher, M.; Harkewicz, Richard; Morrissey, D. J.; Sherrill, B. M.; Steiner, M.; Orr, N. A.; Winger, J. A.

doi:10.1103/physrevc.49.46

Cited by 25 publications

(9 citation statements)

References 11 publications

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“…The log(ft) values and Gammow-Teller transition strengths (B(GT)) were calculated for all β decay branches using methods described in Refs. [24,25], respectively. The values are given in Table IV with the corresponding values from shell model calculations.…”

Section: A β Decay Of 19 Nmentioning

confidence: 98%

β-delayed neutron decay ofN19andN20

et al. 2006

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The results of the first spectroscopic studies of delayed neutron and γ emission following the β decay of 19 N and 20 N are reported. Nuclides were produced by fragmenting an 80 MeV/nucleon 22 Ne beam in a 546 mg/cm 2 thick Be target and were separated at high velocities with the A1200 fragment separator. The nuclides were implanted in a thin plastic scintillator at the center of an array of neutron scintillators to determine the neutron time-of-flight spectrum. Two hyperpure germanium detectors were used to observe coincident γ events. The β-γ, β-n, and β-n-γ coincidence spectra were analyzed to obtain the energies of the states populated in 18 O, 19 O, and 20 O following the β decay. Eight new neutron energies with a total neutron emission probability of 41.8(9)%, six γ transitions among the excited states of 19 O, and four γ transitions among the excited states of 18 O were identified in the 19 N β decay. Seven new neutron energies with a total neutron emission probability of 42.9(14)%, ten γ transitions among the excited states of 20 O, and two γ transitions among the exited states of 19 O were observed from the 20 N β decay. Half-lives of 336(3) and 136(3) ms were determined for the 19 N and 20 N decays, respectively. The branching ratios of both decays were deduced and compared with USD (universal sd-shell) shell model calculations. The β decay schemes for 19 N and 20 N were deduced.

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Section: A β Decay Of 19 Nmentioning

confidence: 98%

β-delayed neutron decay ofN19andN20

et al. 2006

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“…Hence, a β-decay study is useful for studying neutron-rich nuclei located away from the stability line, owing to the large Q β windows. Over the past several years, a number of such studies have been performed on the structure of light-mass neutron-rich nuclei through the time-of-flight (TOF) measurement of emitted β-delayed neutrons [8,[22][23][24][25].…”

Section: Introductionmentioning

confidence: 99%

β-delayed neutron andγ-ray spectroscopy of17C utilizing spin-polarized
Ueno
¹
,
Miyatake
²
,
Yamamoto
³

et al. 2013
Phys. Rev. C
28
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6
0
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Excited states in 17 C were investigated through the measurement of β-delayed neutrons and γ rays emitted in the β decay of 17 B. In the measurement, three negative-parity states and two inconclusive states, were identified in 17 C above the neutron threshold energy, and seven γ lines were identified in a β-delayed multiple neutron emission of the 17 B β decay. From these transitions, the β-decay scheme of 17 B was determined. In particular, a de-excitation 1766-keV γ line from the first excited state of 16 C was observed in coincidence with the emitted β-delayed neutrons, and this changes the previously reported β-decay scheme of 17 B and level structure of 17 C. In the present work, the β-NMR technique is combined with the β-delayed particle measurements using a fragmentation-induced spin-polarized 17 B beam. This new scheme allows us to determine the spin parity of β-decay feeding excited states based on the difference in the discrete β-decay asymmetry parameters, provided the states are connected through the Gamow-Teller transition. In this work, I π = 1/2 − , 3/2 − , and (5/2 − ) are assigned to the observed states at E x = 2.71(2), 3.93(2), and 4.05(2) MeV in 17 C, respectively.

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“…In classical studies of β-delayed neutron emission in light nuclei individual neutron-emitting states can be observed (see, e.g., [31,32]). As indicated in the introduction, the neutron energy distribution of midmass nuclei studied using limited resolution devices does not correspond to individual resonances [7].…”

mentioning

confidence: 99%

Evidence for Gamow-Teller Decay ofNi78Core from Beta-Delayed Neutron Emission Studies

et al. 2016

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The β-delayed neutron emission of 83;84 Ga isotopes was studied using the neutron time-of-flight technique. The measured neutron energy spectra showed emission from states at excitation energies high above the neutron separation energy and previously not observed in the β decay of midmass nuclei. The large decay strength deduced from the observed intense neutron emission is a signature of Gamow-Teller transformation. This observation was interpreted as evidence for allowed β decay to 78 Ni core-excited states in 83;84 Ge favored by shell effects. We developed shell model calculations in the proton fpg 9=2 and neutron extended fpg 9=2 þ d 5=2 valence space using realistic interactions that were used to understand measured β-decay lifetimes. We conclude that enhanced, concentrated β-decay strength for neutron-unbound states may be common for very neutron-rich nuclei. This leads to intense β-delayed high-energy neutron and strong multineutron emission probabilities that in turn affect astrophysical nucleosynthesis models. DOI: 10.1103/PhysRevLett.117.092502 β-delayed neutron emission from fission fragments was first observed in 1939 following the neutron bombardment of uranium salts [1]. It was recognized that the delayed neutron energies and emission probabilities, P n , are important parameters to model environments that involve neutron-rich isotopes. Two of the main applications are in nuclear reactor physics [2] and r-process nucleosynthesis [3]. Because β-delayed neutron precursors are neutron rich and far from stability, they are always relatively difficult to produce and study. Advances in detector capabilities allowed for pioneering measurements of neutron emission spectra of fission fragments [4,5]. In these experiments, resonancelike behavior was observed in the neutron emission spectrum [4,6].These efforts were halted in the following decade by several factors. First, it became increasingly difficult to produce species with larger neutron excess. Second, the very influential work by Hardy, Johnson, and Hansen on "pandemonium" attributed the features of the neutron spectra to purely statistical effects and warned against overinterpretation of the measurements [7]. Misinterpretations of their work attributed decay observables of all heavy nuclei to gross features of the decay strength and statistical fluctuations of the level density. A more accurate depiction of their work is that neutron emission characteristics cannot be interpreted without considering the effects of high level density. The pandemonium controversy [8] arose partly from the fact that, at the time, there was no capability to compute nuclear properties using a sufficiently complete microscopic model of the nucleus.State-of-the-art models are now capable of computing decay properties of atomic nuclei, such as lifetimes and branching ratios. It has become increasingly clear that the β-decay observables are profoundly influenced by nuclearPublished by the American Physical Society under the terms of the Creative Commons Attribution 3.0 Lic...

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Study of the β-delayed neutron decay ofN18

Cited by 25 publications

References 11 publications

β-delayed neutron decay ofN19andN20

β-delayed neutron decay ofN19andN20

β-delayed neutron andγ-ray spectroscopy of17C utilizing spin-polarized
Ueno
¹
,
Miyatake
²
,
Yamamoto
³

et al. 2013
Phys. Rev. C
28
1
6
0
View full text Add to dashboard Cite

Evidence for Gamow-Teller Decay ofNi78Core from Beta-Delayed Neutron Emission Studies

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Study of the β-delayed neutron decay ofN18

Cited by 25 publications

References 11 publications

β-delayed neutron decay ofN19andN20

β-delayed neutron decay ofN19andN20

β-delayed neutron andγ-ray spectroscopy of17C utilizing spin-polarizedUeno1, Miyatake2, Yamamoto3 et al. 2013Phys. Rev. C28160View full textAdd to dashboardCite

Evidence for Gamow-Teller Decay ofNi78Core from Beta-Delayed Neutron Emission Studies

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Product

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β-delayed neutron andγ-ray spectroscopy of17C utilizing spin-polarized
Ueno
¹
,
Miyatake
²
,
Yamamoto
³

et al. 2013
Phys. Rev. C
28
1
6
0
View full text Add to dashboard Cite