Double neutron capture in62Ni

Harder, Alexander; Michaelsen, Søren; Jungclaus, A.; Lieb, Klaus; Williams, A. P.; Börner, H. G.; Trautmannsheimer, M.

doi:10.1007/bf01291590

Cited by 18 publications

(24 citation statements)

References 24 publications

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“…Although 2922.1-and 3578.3-keV γ rays were observed in the 63 Ni(n,γ ) work [6] and would fit the 4268.4 → 1345.8-and 3578.7 → 0-keV transitions, respectively, no evidence of coincidence could be found in the present study. Therefore, they are not placed in the decay scheme.…”

Section: A the 64 Co Decay Schemecontrasting

confidence: 52%

“…Hence, the 64 Co to levels of 64 Ni. The seven γ rays with unmarked solid lines (black online) were observed and placed in the level scheme by Harder et al in their study of the neutron-capture γ spectrum [6]. The six γ rays marked with a rectangle (blue online) were observed by Harder et al but not placed in the level scheme.…”

Section: A the 64 Co Decay Schemementioning

confidence: 92%

“…3. Of the 18 γ -ray lines shown, the seven unmarked transitions with solid lines (black online) were previously established as depopulating levels identified in 64 Ni following the 63 Ni(n,γ ) 64 Ni reaction by Harder et al [6]. Using coincidence evidence, six additional γ rays, marked by a rectangle (blue online), that were reported by Harder et al, were placed in the level scheme.…”

Section: A the 64 Co Decay Schemementioning

confidence: 99%

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Gamow-Teller decay population of64Ni levels in the decay of1+64Co

et al. 2012

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The 64 Co β-decay feeding levels in the well-studied 64 Ni nucleus were investigated. Whereas the previously known 64 Co decay scheme merely contained 2 γ rays, the decay scheme established in this work contains 18, of which 5 are observed in this work and 6 were previously observed in an (n,γ ) study but not placed in the 64 Ni level scheme. Surprisingly, one additional level-placed at an excitation energy of 3578.7 keV-could be determined. The observed β-decay paths involve allowed νf 5/2 → πf 7/2 and νp 1/2 → πp 3/2 transitions. Three strongly fed levels around 4 MeV are interpreted to possess possible proton-intruder character.

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Section: A the 64 Co Decay Schemecontrasting

confidence: 52%

Section: A the 64 Co Decay Schemementioning

confidence: 92%

Section: A the 64 Co Decay Schemementioning

confidence: 99%

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Gamow-Teller decay population of64Ni levels in the decay of1+64Co

et al. 2012

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“…The 63 Ni sample was produced by irradiating highly enriched 62 Ni in a thermal reactor [12,20,21]. Since the irradiation took place more than 20 years ago, the original 63 Ni fraction had partially decayed to 63 Cu.…”

mentioning

confidence: 99%

“…1, we show the neutron capture path in the Ni-Cu-Zn region during He core and at high neutron density during C shell burning. Up to now the stellar cross section of 63 Niðn; Þ 64 Ni relied on calculations or extrapolations of experimental values at thermal neutron energies (0.025 eV) [10][11][12]. Theoretical predictions for the Maxwellian averaged cross section (MACS) at kT ¼ 30 keV are ranging from 24 to 54 mb [13][14][15][16][17].…”

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confidence: 99%

Neutron Capture Cross Section of UnstableNi63: Implications for Stellar Nucleosynthesis

Lederer¹,

Massimi²,

Altstadt³

et al. 2013

Phys. Rev. Lett.

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Thermal neutron capture?-ray spectroscopy of59Ni and61Ni

Harder

Michaelsen

Lieb

et al. 1993

Z. Physik A - Hadrons and Nuclei

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Abstract. The 7-radiation emitted after thermal neutron capture in isotopically enriched 58Ni and 6~ was measured at the ILL high flux reactor by means of Ge/NaI detectors operated in Compton suppression and pair spectrometer mode. The neutron binding energies were determined as B.(59Ni) = 8999.15(23) keV and Bn(61Ni) = 7820.07(20) keV; some 95% of the total y-ray fluxes through s9,61Ni were assigned. The y-ray strength functions of the primary transitions and the level densities are discussed. 21.10.Ma; 23.20.Lv; 25.40.Lw; 27.50.+e PACS: MotivationThe 7-ray decay of the capture state(s) populated in thermal neutron capture reactions is considered to be a nonselective process and thus enables one to establish "complete" level schemes up to about half the neutron binding energy B, and within the spin window bound by s-wave capture and primary dipole transitions. Previous detailed studies of light and medium nuclei [1,2] have shown that the assignment of new states is essentially limited by the increasing level density and decreasing phase space of primary transitions, for given capture crosssections and spectrometer resolution and efficiency.Previous (n, ~) studies in the even-mass nickel targets [3] have shown deviations from this behaviour insofar as the primary spectra are dominated by very few strong transitions to low-lying negative-parity states which account for some 70%-90% of the primary flux. This direct mechanism thus dominates the capture process and leaves correspondingly little flux to higher excited states; this flux was not fully resolved up to now. With the high neutron flux available at the ILL reactor and a high resolution pair spectrometer we hoped to be able to identify the missing portions of the primary spectra Supported by Deutsches BMFT of the 5s'6~ 7) reactions, to identify new excited states and make spin-parity assignments. This information, together with the results from charged-particle induced reactions then should allow us to derive level densities and ~-ray strength functions in the semi-magic Z=28 nickel isotopes, and compare them to findings for N ~_ 20, 28 and 50 neutron magic nuclei [4][5][6][7][8][9].This present work complements our previous studies of the 6~Ni(n, ~)63Ni and 6ZNi(2 n, 7)64Ni reactions [10] and the GRID lifetime measurements in 59'61Ni by U1-big et al. [11]. In this latter work, assumptions concerning the feeding mechanism of several excited states had to be inferred which now can be checked with the present data. Ulbig and co-authors [11,12] also performed extensive shell model calculations of the negative parity states in 59Ni. Experimental procedureThe experimental procedure followed the method applied in our previous neutron capture studies on 31p, s~ 86'87'aasr and 62Ni targets [5-8, 10, 13] where further details of the experimental set-up and data analysis are given. First the 58Ni target, consisting of ca. 130mg of metallic powder (isotopical enrichment 99.8%), was exposed to a thermal neutron flux of 5.5.1014 neutrons/cm 2 s near the core of the ILL h...

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Double neutron capture in62Ni

Cited by 18 publications

References 24 publications

Gamow-Teller decay population of64Ni levels in the decay of1+64Co

Gamow-Teller decay population of64Ni levels in the decay of1+64Co

Neutron Capture Cross Section of UnstableNi63: Implications for Stellar Nucleosynthesis

Thermal neutron capture?-ray spectroscopy of59Ni and61Ni

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