Shell effects in Pb(p,<i>x</i>n) preequilibrium neutron emission

Harder, K.; Kaminsky, A.; Mordhorst, E.; Scobel, W.; Trabandt, Mathias

doi:10.1103/physrevc.36.834

Cited by 15 publications

(10 citation statements)

References 16 publications

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“…We have measured spectra from (t9, x n) reactions on a whole series of Pd isotopes and compared them with preequilibrium-model calculations. These investigations extend the work for nuclei around closed neutron and/or proton shells [5,6,14] and supplement the information from DWBA and coupied-channel calculations for the (p, p') reactions and the (p, n) transitions to the isobar analogues for the target nuclei under study [17]. The high-energy part of the neutron spectra measured with improved (250 keV) energy resolution displays structure differing from isotope to isotope.…”

Section: Discussionmentioning

confidence: 94%

Preequilibrium emission in (p, x n) reactions on palladium isotopes

Hölbling

Čaplar

Stamer

et al. 1991

Z. Physik A - Hadrons and Nuclei

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Energy spectra of neutrons from the lO4, 105,106, lO8,110pd(p ' xn) reactions at E v = 26.1 MeV have been measured using the time-of-flight technique with good overall energy resolution (<250 keV). The hard part of angle-integrated spectra corresponding to low residual excitations (U<6MeV) exhibits pronounced structure varying from isotope to isotope. The observed structure can be reasonably well described by preequilibrium-model calculations with two-quasiparticle state densities for proton-particle neutron-hole configurations based on Nilsson-model single-particle levels instead of equidistant ones. The influence of nuclear deformation and pairing on preequilibrium particle emission is explored.

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Section: Discussionmentioning

confidence: 94%

Preequilibrium emission in (p, x n) reactions on palladium isotopes

Hölbling

Čaplar

Stamer

et al. 1991

Z. Physik A - Hadrons and Nuclei

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“…The calculated results of the energy spectra of neutron emission for p+ 204,206,207,208 Pb reactions are compared with the experimental data [18] at incident proton energy 25.5 MeV as shown in Fig. 5.…”

Section: Theoretical Results and Analysismentioning

confidence: 99%

The cross sections and energy spectra of the particle emission in proton induced reaction on ^{204,206,207,208}Pb and ²⁰⁹Bi

Zhang

Liang

et al. 2017

EPJ Web Conf.

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Abstract. All cross sections of proton induced reactions, angular distributions, energy spectra and double differential cross sections of neutron, proton, deuteron, triton, helium and alpha-particle emissions for p+ 204,206,207,208 Pb, 209 Bi reactions are consistently calculated and analyzed at incident proton energies below 200 MeV. The optical model, the distorted wave Born approximation theory, the unified Hauser-Feshbach and exciton model which includes the improved Iwamoto-Harada model are used. Theoretically calculated results are compared with the existing experimental data.

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“…Há alguns poucos trabalhos que mediram as seções de choque para as reações y Pb(p, xn) y−x−1 Bi a energias abaixo de 40 MeV, (Titarenko, Ignatyuk et al, 2016;Bell e Skarsgard, 1956;Schery, Lind et al, 1974;Harder, Kaminsky et al, 1987). (Bell e Skarsgard, 1956) fez um amplo estudo de reações (p, xn) para o chumbo e o bismuto a energias maiores que 10 MeV, tanto do ponto de vista experimental, como em comparação com modelos teóricos.…”

Section: Resultados Experimentaisunclassified

“…Já (Titarenko, Ignatyuk et al, 2016) estudou essas seções de choque para energias entre 40 MeV < E p < 2.6 GeV. (Harder, Kaminsky et al, 1987) estudou a reação (p, xn) para os isótopos do chumbo a 25.5 MeV, relacionando com efeitos de camada para a emissão neutrônica. Já (Schery, Lind et al, 1974) estudou as reações 206,207,208 Pb(p, n) 206,207,208 Bi a 25.8 MeV, com foco no potencial nuclear e distribuição de nêutrons e prótons.…”

Section: Resultados Experimentaisunclassified

“…Uma análise cuidadosa dos níveis de energia do chumbo mostra que ainda há possíveis rotas de decaimentos de estados excitados não completamente confirmadas. Assim, a despeito da ampla utilização do chumbo como blindagem, o estudo de suas propriedades nucleares ainda precisam ser mais estudadas, (Richel, Albouy et al, 1976;Richel, Albouy et al, 1978;Harder, Kaminsky et al, 1987). Mesmo a taxa de produção dos estados isoméricos do bismuto em reações (p, xn), casos do 201−203 Bi, ou não foram plenamente determinados ou só o foram para energias acima de 50 MeV, (Schery, Lind et al, 1974;Titarenko, Ignatyuk et al, 2016;Richel, Albouy et al, 1976;Richel, Albouy et al, 1978;Harder, Kaminsky et al, 1987;National Nuclear Data Center, 2008).…”

Section: Solunclassified

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Estudo das reações >sup<nat>/sup<Pb(p,xn)>sup<201-207>/sup<Bi e discussão de possíveis contribuições astrofísicas para o processo r

Guillaumon¹

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We analyzed the possible neutron sources for r-process production in stars of first, second and third generation. We propose a new mechanism of dynamic production for r-elements based on (p, xn) and (n, ) reactions on heavy nuclides. We called this r 2 p mechanism. We investigated proton and neutron energies that make that mechanism possible. Our model was able to reproduce r-elements like thorium and uranium with neutron flux of 10 20 neutrons ⋅ s −1 cm −3 . Critical conditions for neutrons flux of > 10 30 neutrons ⋅ s −1 cm −3 or slow r-process neutron flux (∼ 10 10 neutrons ⋅ s −1 cm −3 ) can be reproduced by our model, depending on the initial conditions. We discussed possible astrophysical sites for that mechanism and possible consequences for 232 Th, 235,238 U, and 244 Pu nucleochronometers.The study of nat Pb(p, xn) 201−207 Bi reactions have been made using 18−30 MeV proton beam energies from IPEN/CNEN's cyclotrons. We measured the cross-sections for these reactions and compared with theoretical simulations made with TALYS code. The nuclear reaction threshold of 204 Pb(p, 3n) 202 Bi, and 204 Pb(p, 4n) 201 Bi are determined. We discuss possible consequences of that results for the r-process. Also, we discuss possible discrepancies among our results and theoretical simulations for the neutron bind energy and Coulomb barrier of bismuth.The spectroscopy study with HPGe detectors has been made in association with the half-live measurement in order to fully identify the isotopes' formation. We noted some discrepancies in the energy levels of the IT isotope 204 Pb that comes from 204,206 Pb(p, xn) 204 Bi reactions. This may be related to a new possible state for this reaction at low energies above the Coulomb barrier. Finally, we have for the first time measured the cross reactions for these reactions at that proton energies.A new non-linear energy calibration method is developed, based in Principal Components Analysis (PCA). Our method is called Weighted Principal Polynomial Analysis (WPPA). We discuss possible uses of that method in nuclear physics and astronomy measurements. Machine learning for physics analysis could also use that algorithm.

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Shell effects in Pb(p,xn) preequilibrium neutron emission

Cited by 15 publications

References 16 publications

Preequilibrium emission in (p, x n) reactions on palladium isotopes

Preequilibrium emission in (p, x n) reactions on palladium isotopes

The cross sections and energy spectra of the particle emission in proton induced reaction on ^{204,206,207,208}Pb and ²⁰⁹Bi

Estudo das reações >sup<nat>/sup<Pb(p,xn)>sup<201-207>/sup<Bi e discussão de possíveis contribuições astrofísicas para o processo r

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Shell effects in Pb(p,xn) preequilibrium neutron emission

Cited by 15 publications

References 16 publications

Preequilibrium emission in (p, x n) reactions on palladium isotopes

Preequilibrium emission in (p, x n) reactions on palladium isotopes

The cross sections and energy spectra of the particle emission in proton induced reaction on 204,206,207,208Pb and 209Bi

Estudo das reações >sup<nat>/sup<Pb(p,xn)>sup<201-207>/sup<Bi e discussão de possíveis contribuições astrofísicas para o processo r

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The cross sections and energy spectra of the particle emission in proton induced reaction on ^{204,206,207,208}Pb and ²⁰⁹Bi