Investigation of new neutron-rich gold isotopes203Au and205Au

Wennemann, C.; Schmidt‐Ott, W. D.; Hild, T.; Krumbholz, Katrin; Kunze, V.; Meißner, F.; Keller, H.; Kirchner, R.; Roeckl, E.

doi:10.1007/bf01292375

Cited by 34 publications

(4 citation statements)

References 20 publications

(21 reference statements)

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“…Apart from the discrepancies found for the 208,209 Hg isotopes, a rather good agreement is found between the present results and previously published experimental data. In the case of gold isotopes, all half-lives are fully compatible with those reported in previous measurements [18,[73][74][75][76], which are in reasonable agreement with DF3 + cQRPA for N 126. For 206 Au (N = 126) the half-life obtained confirms the recent value published in Ref.…”

Section: Summary and Discussionsupporting

confidence: 90%

β -decay half-lives and β -delayed neutron emission probabilities for several isotopes of Au, Hg, Tl, Pb, and Bi, beyond N=126

Caballero-Folch¹,

Domingo‐Pardo²,

Agramunt³

et al. 2017

Phys. Rev. C

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Background: There have been measurements on roughly 230 nuclei that are β-delayed neutron emitters. They range from 8 He up to 150 La. Apart from 210 Tl, with a branching ratio of only 0.007%, no other neutron emitter has been measured beyond A = 150. Therefore, new data are needed, particularly in the region of heavy nuclei around N = 126, in order to guide theoretical models and help understand the formation of the third r-process peak at A ∼ 195. Purpose: To measure both β-decay half-lives and neutron branching ratios of several neutron-rich Au, Hg, Tl, Pb, and Bi isotopes beyond N = 126. Method: Ions of interest were produced by fragmentation of a 238 U beam, selected and identified via the GSI-FRS fragment separator. A stack of segmented silicon detectors (SIMBA) was used to measure ion implants and β decays. An array of 30 3 He tubes embedded in a polyethylene matrix (BELEN) was used to detect neutrons with high efficiency and selectivity. A self-triggered digital system is employed to acquire data and to enable time correlations. The latter were analyzed with an analytical model and results for the half-lives and neutron-branching ratios were derived by using the binned maximum-likelihood method. Results: Twenty new β-decay half-lives are reported for [204][205][206][208][209][210][211][211][212][213][214][215][216][215][216][217][218][218][219][220] Bi, nine of them for the first time. Neutron emission probabilities are reported for 210,211 Hg and 211-216 Tl. 2469-9985/2017/95(6)/064322(16) 064322-1 Published by the American Physical Society R. CABALLERO-FOLCH et al. PHYSICAL REVIEW C 95, 064322 (2017) Conclusions:The new β-decay half-lives are in good agreement with previous measurements on nuclei in this region. The measured neutron emission probabilities are comparable to or smaller than values predicted by global models such as relativistic Hartree Bogoliubov plus the relativistic quasi-particle random phase approximation (RHB + RQRPA).

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Section: Summary and Discussionsupporting

confidence: 90%

β -decay half-lives and β -delayed neutron emission probabilities for several isotopes of Au, Hg, Tl, Pb, and Bi, beyond N=126

Caballero-Folch¹,

Domingo‐Pardo²,

Agramunt³

et al. 2017

Phys. Rev. C

View full text Add to dashboard Cite

show abstract

“…Apart from the discrepancies found for the 208,209 Hg isotopes, a rather good agreement is found between the present results and previously published experimental data. In the case of gold isotopes, all half-lives are fully compatible with those reported in previous measurements [16,[58][59][60], which are in reasonable agreement with DF3+cQRPA for N ≤ 126. For 206 Au (N = 126) the half-life obtained confirms the recent value published in Ref.…”

Section: Summary and Discussionsupporting

confidence: 90%

$β$-decay half-lives and $β$-delayed neutron emission probabilities for several isotopes of Au, Hg, Tl, Pb and Bi, beyond N=126

Caballero-Folch,

Domingo-Pardo,

Agramunt

et al. 2017

Preprint

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Background: Previous measurements of β-delayed neutron emitters comprise around 230 nuclei, spanning from the 8 He up to 150 La. Apart from 210 Tl, with a minuscule branching ratio of 0.007%, no other neutron emitter is measured yet beyond A = 150. Therefore new data are needed, particularly in the heavy mass region around N=126, in order to guide theoretical models and to understand the formation of the third r-process peak at A ∼ 195. Purpose: To measure both, β-decay half-lives and neutron branching ratios of several neutron-rich Au, Hg, Tl, Pb and Bi isotopes beyond N = 126. Method: Ions of interest are produced by fragmentation of a 238 U beam, selected and identified via the GSI-FRS fragment separator. A stack of segmented silicon detectors (SIMBA) is used to measure ion-implants and β-decays. An array of 30 3 He tubes embedded in a polyethylene matrix (BELEN) is used to detect neutrons with high efficiency and selectivity. A self-triggered digital system is employed to acquire data and to enable time-correlations. The latter are analyzed with an analytical model and results for the half-lives and neutron-branching ratios are derived using the binned Maximum-Likelihood method. Results: Twenty new β-decay half-lives are reported for 204−206 Au, 208−211 Hg, 211−216 Tl, 215−218 Pb and 218−220 Bi, nine of them for the first time. Neutron emission probabilities are reported for 210,211 Hg and 211−216 Tl. Conclusions: The new β-decay half-lives are in good agreement with previous measurements in this region. The measured neutron emission probabilities are comparable or smaller than values predicted by global models like RHB+RQRPA.

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“…This excess is independent of the odd-even behavior arising from the omission of the isosinglet nucleon-nucleon interaction in the model [8]. Instead, the minor role given to the firstforbidden β strength can be seen as responsible for the large deviations: Systematic studies of partial β-decay schemes for some of these nuclei [35,36,38] indicate that the most intense β transitions populate low-lying states of opposite parity, while weaker Gamow-Teller decays, if predicted to exist, feed levels at higher energies. For the Tl isotopes shown in Fig.…”

Section: Infn-laboratori Nazionali DI Legnaro I-35020 Legnaro Italymentioning

confidence: 99%

Half-Life Systematics across theN=126Shell Closure: Role of First-Forbidden Transitions in theβDecay of Heavy Neutron-Rich Nuclei

et al. 2014

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This Letter reports on a systematic study of β-decay half-lives of neutron-rich nuclei around doubly magic 208 Pb. The lifetimes of the 126-neutron shell isotone 204 Pt and the neighboring [200][201][202] Ir, 203 Pt, 204 Au are presented together with other 19 half-lives measured during the "stopped beam" campaign of the rare isotope investigations at GSI collaboration. The results constrain the main nuclear theories used in calculations of r-process nucleosynthesis. Predictions based on a statistical macroscopic description of the first-forbidden β strength reveal significant deviations for most of the nuclei with N < 126. In contrast, theories including a fully microscopic treatment of allowed and first-forbidden transitions reproduce more satisfactorily the trend in the measured half-lives for the nuclei in this region, where the r-process pathway passes through during β decay back to stability. DOI: 10.1103/PhysRevLett.113.022702 PACS numbers: 25.70.Mn, 23.40.-s, 26.30.Hj, 27.80.+w In very hot, neutron-rich stellar environments, the r process of nucleosynthesis is ignited in a series of rapid neutron captures on seed nuclei of the Fe group, thus creating very exotic neutron-rich nuclei that β decay back to stability around the neutron shell closures with N ¼ 50, 82, and 126. In these "waiting-point" regions, matter is accumulated at masses A ∼ 80, 130, and 195, thus creating the so-called first, second, and third r-abundance peaks. These basic features of the r process were established more than half a century ago [1]. However, how the heavy nuclei from Ni to U are synthesized is one of the major unanswered questions of modern physics because of the large uncertainties in the path, time scale, and astrophysical conditions for the rapid neutron capture process to develop [2]. Observational constraints such as the elemental abundances in metal-poor stars or in solar system material help to determine astronomical sites where it might occur [3,4]. Concurrently, β-decay properties of very exotic nuclei near the path, such as β half-lives, are critical in determining the observed abundances [5]. Since many of the r-process progenitors cannot be accessed with present radioactive ion beam facilities, estimates of r-process nucleosynthesis generally rely upon predictions of stateof-the-art nuclear models, based on the properties of nuclei far from stability [6][7][8][9][10][11]. But at extreme values of isospin, theoretical predictions may be biased by microscopic structural effects that modify the shape of the β-strength function, such as nuclear shell quenching or deformation [12,13]. Until now, such theories have only been tested with information on β decay around the first two waiting points

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Investigation of new neutron-rich gold isotopes203Au and205Au

Cited by 34 publications

References 20 publications

β -decay half-lives and β -delayed neutron emission probabilities for several isotopes of Au, Hg, Tl, Pb, and Bi, beyond N=126

β -decay half-lives and β -delayed neutron emission probabilities for several isotopes of Au, Hg, Tl, Pb, and Bi, beyond N=126

$β$-decay half-lives and $β$-delayed neutron emission probabilities for several isotopes of Au, Hg, Tl, Pb and Bi, beyond N=126

Half-Life Systematics across theN=126Shell Closure: Role of First-Forbidden Transitions in theβDecay of Heavy Neutron-Rich Nuclei

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