The fission products 81Se and 83Se

Croall, I.F.; Willis, H.H.

doi:10.1016/s0022-1902(62)90420-7

Cited by 25 publications

(4 citation statements)

References 6 publications

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“…All such states studied in this work are given in table 2. Usually, with proton-induced fission, the high-spin isomeric state is more strongly populated than the ground state (see, e.g., [34,35] or [36] for far asymmetric fission). In the case of 62 Mn the spin assignment of the isomers is not known and therefore a careful analysis is needed.…”

Section: Identification Of Isomersmentioning

confidence: 99%

Recoil-ion trapping for precision mass measurements

et al. 2012

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Abstract. For the first time masses of recoiling daughter ions have been measured that were held after beta-decay in a buffer-gas-filled Penning trap. From the masses of the trapped beta-decaying manganese ions 61-63 Mn + and the daughter recoil-ions 61-63 Fe + the Q values of 61-63 Mn have been deduced with absolute uncertainties of about 5 keV. The observed yields of iron ions are compared to the results from simulations, which confirm a recoil-ion trapping efficiency of about 50%.

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Section: Identification Of Isomersmentioning

confidence: 99%

Recoil-ion trapping for precision mass measurements

et al. 2012

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“…But changes of the order of 20% are not ruled out. There have been some experiments to examine [40][41][42] changes in the fission yields of isotopes that sit at the peaks of the mass distribution, but the results are discrepant: some experiments observe changes [40,41] and others do not [42]. One issue in considering the hardness of the spectrum is that since epithermal [20].…”

mentioning

confidence: 99%

Possible origins and implications of the shoulder in reactor neutrino spectra

et al. 2015

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We analyze within a nuclear database framework the shoulder observed in the antineutrino spectra in current reactor experiments. We find that the ENDF/B-VII.1 database predicts that the antineutrino shoulder arises from an analogous shoulder in the aggregate fission beta spectra. In contrast, the JEFF-3.1.1 database does not predict a shoulder for two out of three of the modern reactor neutrino experiments, and the shoulder that is predicted by JEFF-3.1.1 arises from 238 U. We consider several possible origins of the shoulder, and find possible explanations. For example, there could be a problem with the measured aggregate beta spectra, or the harder neutron spectrum at a light-water power reactor could affect the distribution of beta-decaying isotopes. In addition to the fissile actinides, we find that 238 U could also play a significant role in distorting the total antineutrino spectrum. Distinguishing these and quantifying whether there is an anomaly associated with measured reactor neutrino signals will require new short-baseline experiments, both at thermal reactors and at reactors with a sizable epithermal neutron component.Modern reactor neutrino experiments measuring θ 13 , such as Daya Bay [1], RENO [2], and Double Chooz [3], involve detectors both near and far from the reactors. The shape and magnitude of the antineutrino spectra emitted from the reactors have been measured to high accuracy in the near detectors of both Daya Bay and RENO. The Daya Bay near-detector has also provided an absolute determination of the reactor antineutrino flux, and this is consistent in magnitude with the previous world average short-baseline reactor neutrino experiments. As such, the measured magnitude is consistent with a deficit with respect to the most recent estimates [4,5] of the expected reactor antineutrino flux. The absolute magnitude of the RENO flux has yet to be published. However, in the near detector of both RENO and Daya Bay the shapes of the measured spectra are not consistent with the antineutrino spectrum predictions [4,5] that we refer to as the Huber-Mueller model. Most notably, the measured antineutrino spectra exhibit a significant shoulder relative to the model predictions at antineutrino energies ∼ 5 − 7 MeV. The spectra measured at Daya Bay, RENO, and Double Chooz all exhibit this shoulder. Thus, there are two puzzles associated with measured reactor antineutrino spectra: (1) the yield in all short-baseline experiments is lower than current models, and (2) the shape of the measured spectra deviate from these model predictions. However, these two issues are not necessarily related.In the Daya Bay, RENO and Double Chooz experiments the antineutrinos are measured by detecting the positrons produced in inverse beta decay on the protons (ν e + p → n + e + ) in the detector, and the positron energy is reconstructed from the scintillation light created by the kinetic energy of the positron and its annihilation. The antineutrino spectrum S(E ν ) emitted from a reactor is determined by [6] the reactor ther...

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“…Studies of isomer ratios formed in nuclear reactions on various elements (1)(2)(3)(4)(5) and by nuclear fission of heavy elements (6)(7)(8)(9)(10)(11)(12)(13)(14) by particles with thermal, low, and medium energies have been carried out. These have been particularly helpful in the understanding of angular momentum effects in these various reactions.…”

Section: Introductionmentioning

confidence: 99%

Analysis of ¹³⁴Cs Isomer Ratios in the Fission of ²³⁷Np with Protons in the Energy Range 20–85 MeV

Rao¹,

Yaffe²

1972

Can. J. Chem.

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An analysis has been made of the isomer ratio, cr,/(a, + a,) for '34Cs isomers formed in the fission of 237Np by protons of energies 20-85 MeV. Compound nucleus formation was assumed up to a bombarding energy of 50 MeV, with direct interaction as the mechanism at higher energies. Values of the root-meansquare angular momentum of 12h at 20 MeV and 16-18h at 60-85 MeV bombarding energy agree with the experimental results. The results are consistent with the hypothesis that angular momentum is generated in the fission process.On a f a~t I'analyse du rapport a,/(a,+ a,)pour les isomeres 'j4Cs formes lors de la fiss~on du 237Np par des protons d'energie de 20 a 85 MeV. La formation du noyau du composi: est supposte jusqu'i une tnerg~e de bombardement de 50 MeV, pour des energies plus elevees le mtcanlsme est du type interaction directe. Le valeurs des racides carrtes moyennes du moment angula~re de 12h a 20 MeV et 16-18h a 60-80 MeV sont en accord avec les resultats exptrimentaux. Les resultats sont compatibles avec l'hypothese que le moment angulaire est produit dans le processus de fission

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The fission products 81Se and 83Se

Cited by 25 publications

References 6 publications

Recoil-ion trapping for precision mass measurements

Recoil-ion trapping for precision mass measurements

Possible origins and implications of the shoulder in reactor neutrino spectra

Analysis of ¹³⁴Cs Isomer Ratios in the Fission of ²³⁷Np with Protons in the Energy Range 20–85 MeV

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The fission products 81Se and 83Se

Cited by 25 publications

References 6 publications

Recoil-ion trapping for precision mass measurements

Recoil-ion trapping for precision mass measurements

Possible origins and implications of the shoulder in reactor neutrino spectra

Analysis of 134Cs Isomer Ratios in the Fission of 237Np with Protons in the Energy Range 20–85 MeV

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Analysis of ¹³⁴Cs Isomer Ratios in the Fission of ²³⁷Np with Protons in the Energy Range 20–85 MeV