Temperature-tuned Maxwell–Boltzmann neutron spectra for kT ranging from 30 up to 50keV for nuclear astrophysics studies

Martín-Hernández, Guido; Mastinu, P.; Praena, J.; Dzysiuk, N.; Noy, R. Capote; Pignatari, M.

doi:10.1016/j.apradiso.2012.05.004

Cited by 12 publications

(5 citation statements)

References 31 publications

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“…Unfortunately, for many isotopes TOF measurements are missing and the evaluations show important discrepancies. This fact was pointed out by G. Martín-Hernández et al [22] showing the conflicting situation of a stable isotope, 82 Se. Therefore, it is advantageous to generate MNS at different kT s and within the same experimental setup, in order to measure the MACS at the kT of interest and to reduce systematic uncertainties.…”

Section: Quasi Maxwellian Neutron Spectrum: Karlsruhementioning

confidence: 82%

“…The rest of the neutrons is provided by the partial activation of the 22 Ne(α,n) 25 Mg at higher temperatures and higher neutron densities during the thermal pulses [34]. Figure 1 (right) shows the neutron capture conditions in the 13 C-pocket where the neutron density is quite low, and a typical unbranched s-process pattern is obtained.…”

Section: Macs By Proton Shaping: 181 Ta(nγ) Astrophysical Implicationsmentioning

confidence: 99%

“…Figure 1 (right) shows the neutron capture conditions in the 13 C-pocket where the neutron density is quite low, and a typical unbranched s-process pattern is obtained. On the other hand, the higher neutron density triggered by the 22 Ne(α,n) 25 Mg activation during the thermal pulses (see figure 2 on the left), causes the open of different branchings, in particular for 181 Hf (Z=72), with decay time scale of about a day at stellar conditions [33]. This implies that during the thermal pulses, the s-process production of 181 Ta is more complex than with lower neutron densities, possibly affected also by the 181 Hf branching.…”

Section: Macs By Proton Shaping: 181 Ta(nγ) Astrophysical Implicationsmentioning

confidence: 99%

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Current quests in nucleosynthesis: present and future neutron-induced reaction measurements

Praena

Pignatari

Mastinu

et al. 2014

EPJ Web of Conferences

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Abstract.We present some open questions in nucleosynthesis focused on the measurement of relevant neutron capture cross-sections and on new experimental methods. We review the recent 63 Ni(n,γ) experiment carried out at the n_TOF facility at CERN and its astrophysical implications as well as future experiments and opportunities at n_TOF. We argue some improvements in the measurement of cross-sections by activation arising from a new method for the generation of stellar neutron spectra. We show preliminary results of the experimental validation of the method. We discuss the astrophysical implications of the 181 Ta(n,γ) stellar cross-section measured with this method. Finally, we describe challenging experiments consisting of in situ radioactive ion beams and stellar neutron beams.

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Section: Quasi Maxwellian Neutron Spectrum: Karlsruhementioning

confidence: 82%

Section: Macs By Proton Shaping: 181 Ta(nγ) Astrophysical Implicationsmentioning

confidence: 99%

Section: Macs By Proton Shaping: 181 Ta(nγ) Astrophysical Implicationsmentioning

confidence: 99%

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Current quests in nucleosynthesis: present and future neutron-induced reaction measurements

Praena

Pignatari

Mastinu

et al. 2014

EPJ Web of Conferences

Self Cite

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“…This method improves the neutron flux at the sample position and avoid the use of moderators. As proposed by Martín-Hernández et al [3], by choosing different thicknesses, different materials, or combinations of both, different thermal temperatures can be obtained with this method. Figure 1 shows a schematic representation of this method.…”

Section: The Methodsmentioning

confidence: 99%

Stellar neutron spectra at 28 keV thermal temperature

2023

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To calculate the reaction rate in the neutron capture processes it is common to work with the Maxwellian Average Cross Section (MACS), defined as the reaction rate scaled by the most probable neutron velocity of the Maxwell-Boltzmann distribution. For MACS determination with lower uncertainties, the need of a neutron spectrum as similar as possible to the stellar one motivates this work. At the CN Van der Graaff accelerator of the LNLINFN laboratories, an experimental measurement is performed to produce a Maxwell-Boltzmann neutron spectrum with 28 keV of thermal temperature. The neutron time-of-flight spectrometry is implemented to determine 0°-90° integrated neutron spectrum, employing the 7Li(p,n)7Be reaction as neutron source, an initial proton energy of 3.17 MeV and a 51 µm thickness aluminum foil, as proton energy shaper.

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“…High quality Maxwell-Boltzmann neutron spectra for thermal energies of the distribution ranging from 30 to 50 keV are predicted [9]. This calculation are carried out by computing the differential yield of the reaction for thick targets which is reigned by the reaction kinematics, the stopping power of protons on Li, and the 7 Li(p,n) 7 Be reaction cross section.…”

Section: Introductionmentioning

confidence: 99%

Excitation function shape and neutron spectrum of theLi7(p,n)Be7reaction near threshold

et al. 2016

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The forward-emitted low energy tail of the neutron spectrum generated by the 7 Li(p,n) 7 Be reaction on a thick target at a proton energy of 1893.6 keV was measured by time-of-flight spectroscopy. The measurement was performed at BELINA (Beam Line for Nuclear Astrophysics) of the Laboratori Nazionali di Legnaro. Using the reaction kinematics and the proton on lithium stopping power the shape of the excitation function is calculated from the measured neutron spectrum. Good agreement with two reported measurements was found. Our data, along with the previous measurements, are well reproduced by the Breit-Wigner single-resonance formula for s-wave particles. The differential yield of the reaction is calculated and the widely used neutron spectrum at a proton energy of 1912 keV was reproduced. Possible causes regarding part of the 6.5% discrepancy between the 197 Au(n,γ ) cross section measured at this energy by Ratynski and Kappeler [Phys. Rev. C 37, 595 (1988)] and the one obtained using the Evaluated Nuclear Data File version B-VII.1 are given.

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Temperature-tuned Maxwell–Boltzmann neutron spectra for kT ranging from 30 up to 50keV for nuclear astrophysics studies

Cited by 12 publications

References 31 publications

Current quests in nucleosynthesis: present and future neutron-induced reaction measurements

Current quests in nucleosynthesis: present and future neutron-induced reaction measurements

Stellar neutron spectra at 28 keV thermal temperature

Excitation function shape and neutron spectrum of theLi7(p,n)Be7reaction near threshold

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