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NSR database version of April 11, 2024.

Search: Author = A.E.Lovell

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2023CA11      Phys.Rev. C 108, 024601 (2023)

M.Catacora-Rios, A.E.Lovell, F.M.Nunes

Complete quantification of parametric uncertainties in (d, p) transfer reactions

NUCLEAR REACTIONS 14C, 16O, 48Ca(d, p), E=7-24 MeV; analyzed mock data generated from a global optical potential and real experimental data for differential σ(θ, E) and asymptotic normalization coefficients (ANC); deduced parametric uncertainties in transfer reactions σ including the uncertainties associated with the final bound state. Metropolis-Hastings Bayesian Markov chain Monte Carlo (MH-MCMC) and three-body model ADWA. Relevance to uncertainty quantification in the design of future experiments.

doi: 10.1103/PhysRevC.108.024601
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2023GI01      Phys.Rev. C 107, 014612 (2023)

N.P.Giha, S.Marin, J.A.Baker, I.E.Hernandez, K.J.Kelly, M.Devlin, J.M.O'Donnell, R.Vogt, J.Randrup, P.Talou, I.Stetcu, A.E.Lovell, O.Litaize, O.Serot, A.Chebboubi, C.-Y.Wu, S.D.Clarke, S.A.Pozzi

Correlations between energy and γ-ray emission in 239Pu(n, f)

NUCLEAR REACTIONS 239Pu(n, f), E=2-40 MeV; measured fragments, En, In, Eγ, Iγ, (fragments)γ-coin, (fragment)n-coin, nγ-coin; deduced γ spectrum, γ multiplicity, linear relation between incident neutron energy and γ multiplicity. Comparison to fission model calculations done with CGMF, FIFRELIN and FREYA codes. Multiplicity results are compared to ENDF/B-VIII.0 data and to experimental data on 238U(n, F), 239Pu(d, F), 233Pu(d, F), 240Pu(d, F) reactions. Broad-spectrum neutron beam produced via spallation reaction of an 800 MeV proton beam on W target (Los Alamos Neutron Science Center). Chi-Nu liquid scintillator array, a hemispherical array of 54 EJ-309 (n- and γ- measurement) surrounding multifoil parallel-plate avalanche counter (PPAC) serving as target and contain ing 239Pu (fragment measurement).

doi: 10.1103/PhysRevC.107.014612
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2023HE11      Phys.Rev. C 108, 014601 (2023)

C.Hebborn, T.R.Whitehead, A.E.Lovell, F.M.Nunes

Quantifying uncertainties due to optical potentials in one-neutron knockout reactions

NUCLEAR REACTIONS 9Be(11Be, n)10Be, (12C, n)11C, E=60 MeV/nucleon; calculated 1n-knockut σ with diffractive-breakup and stripping contributions. 9Be(10Be, 10Be), (11C, 11C), E=60 MeV/nucleon; calculated elastic σ(θ). Bayesian analysis of the reaction model, quantifying parametric uncertainties on the optical potentials, to obtain uncertainty intervals for knockout observables. Optical potentials obtained from many-body calculations with chiral force. Comparison to experimental data.

doi: 10.1103/PhysRevC.108.014601
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2023HE15      Phys.Rev.Lett. 131, 212503 (2023)

C.Hebborn, F.M.Nunes, A.E.Lovell

New Perspectives on Spectroscopic Factor Quenching from Reactions

NUCLEAR REACTIONS 1H(34Ar, d), (36Ar, d), (46Ar, d), E=33 MeV/nucleon; analyzed available data using the Adiabatic Wave Approximation (ADWA); deduced that the spectroscopic strengths of loosely bound nucleons extracted from both probes agree with each other and, although there are still discrepancies for deeply bound nucleons, the slope of the asymmetry dependence of the single-particle strengths inferred from transfer and knockout reactions are consistent within 1 sigma.

doi: 10.1103/PhysRevLett.131.212503
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2023KA11      Phys.Rev. C 107, 044608 (2023)

T.Kawano, A.E.Lovell, S.Okumura, H.Sasaki, I.Stetcu, P.Talou

Consideration of memory of spin and parity in the fissioning compound nucleus by applying the Hauser-Feshbach fission fragment decay model to photonuclear reactions

NUCLEAR REACTIONS 238U(n, X), (γ, X), E<20 MeV; calculated partial population of compound nucleus. 235,238U, 239Pu(γ, F), E=1-20 MeV; calculated prompt fission γ-ray spectra, average number of prompt and delayed neutrons, total kinetic energies, cumulative fission product yields. Hauser-Feshbach statistical calculations of fission fragment decay with HF3D model. Comparison to experimental results and IAEA evaluation.

doi: 10.1103/PhysRevC.107.044608
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2023KE09      Phys.Rev. C 108, 024603 (2023)

K.J.Kelly, M.Devlin, J.M.O'Donnell, D.Neudecker, A.E.Lovell, R.C.Haight, C.Y.Wu, R.Henderson, E.A.Bennett, T.Kawano, J.L.Ullmann, N.Fotiades, J.Henderson, S.M.Mosby, T.N.Taddeucci, P.Talou, M.C.White, J.A.Gomez, H.Y.Lee

Measurement of the 238U(n, f) prompt fission neutron spectrum from 10 keV to 10 MeV induced by neutrons with 1.5-20 MeV energy

NUCLEAR REACTIONS 238U(n, F), E=1.5-20 MeV; measured fission fragments, En, In, neutron time-of-flight, (fragment)n-coin; deduced prompt fission neutron spectrum (PFNS). Systematic trends in PFNS and PFNS ratios for 239Pu, 235U, and 238U obtained in series of Chi-Nu experiments. Comparison to other experimental results, CGMF calculations and data from JEFF-3.3, JENDL-5.0. ENDF/B-VIII libraries. Pulsed white neutron source at Weapons Neutron Research (WNR) facility of the Los Alamos Neutron Science Center (LANSCE). Li-glass array consisting of 22 detectors and liquid scintillator array consisting of 54 detector used for neutron detection, while PPAC used for detecting fission fragments in the frame of Chi-Nu experiment.

doi: 10.1103/PhysRevC.108.024603
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2023LE08      Phys.Rev. C 108, 014608 (2023)

E.Leal-Cidoncha, A.Couture, E.M.Bond, T.A.Bredeweg, C.Fry, T.Kawano, A.E.Lovell, G.Rusev, I.Stetcu, J.L.Ullmann, L.Leal, M.T.Pigni

Measurement of the neutron-induced capture-to-fission cross section ratio in 233U at LANSCE

NUCLEAR REACTIONS 235U(n, F), (n, γ), E=0.007-250 keV; measured Eγ, Iγ, γ-sum, En, In, nγ-coin; deduced capture-to-fission σ ratio, σ(E) of (n, γ) reaction derived from obtained ratio and ENDF/B-VIII.0 fission σ. Comparison to other experimental data, statistical model calculations and data from ENDF/B-VIII.0, JEFF-3.3, and JENDL-5 libraries. Discussed impact of the data on Th-U fuel cycle. Detector for Advanced Neutron Capture Experiments (DANCE) γ-calorimeter composed of 160 BaF2 crystals combined with the neutron detector array at DANCE (NEUANCE) composed of 21 stilbene crystals at Los Alamos Neutron Science Center (LANSCE, LANL).

doi: 10.1103/PhysRevC.108.014608
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2023MU06      Phys.Rev. C 107, 034606 (2023)

M.R.Mumpower, D.Neudecker, H.Sasaki, T.Kawano, A.E.Lovell, M.W.Herman, I.Stetcu, M.Dupuis

Collective enhancement in the exciton model

NUCLEAR REACTIONS 239Pu(n, 2n), E=6-24 MeV; calculated σ(E). 239Pu(n, xn), E=14 MeV; 181Ta, 165(n, xn), E=20 MeV; calculated neutron emission spectra. Calculation with statistical model framework CoH3 with increased one-particle-one-hole state density used in the exciton model. Comparison to experimental data and ENDF/B-VIII.0.

NUCLEAR STRUCTURE 239Pu; calculated 1p-1h state densities.

doi: 10.1103/PhysRevC.107.034606
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2023NE10      Eur.Phys.J. N 9, 35 (2023)

D.Neudecker, A.M.Lewis, E.F.Matthews, J.Vanhoy, R.C.Haight, D.L.Smith, P.Talou, S.Croft, A.D.Carlson, B.Pierson, A.Wallner, A.Al-Adili, L.Bernstein, R.Capote, M.Devlin, M.Drosg, D.L.Duke, S.Finch, M.W.Herman, K.J.Kelly, A.Koning, A.E.Lovell, P.Marini, K.Montoya, G.P.A.Nobre, M.Paris, B.Pritychenko, H.Sjostrand, L.Snyder, V.Sobes, A.Solders, J.Taieb

Templates of Expected Measurement Uncertainties: a CSEWG Effort

NUCLEAR REACTIONS 235U(n, F), E<20 MeV; analyzed available data; deduced nubar mean values and uncertainties.

doi: 10.1051/epjn/2023014
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2023NE12      Eur.Phys.J. N 9, 30 (2023)

D.Neudecker, A.D.Carlson, S.Croft, M.Devlin, K.J.Kelly, A.E.Lovell, P.Marini, J.Taieb

Templates of expected measurement uncertainties for average prompt and total fission neutron multiplicities

RADIOACTIVITY 252Cf(SF); analyzed available data; deduced prompt-fission neutron spectrum (PFNS), nubar uncertainties.

NUCLEAR REACTIONS 239Pu(n, F), E<20 MeV; analyzed available data; deduced prompt-fission neutron spectrum (PFNS), nubar uncertainties.

doi: 10.1051/epjn/2023016
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2022KE01      Phys.Rev. C 105, 044615 (2022)

K.J.Kelly, J.A.Gomez, M.Devlin, J.M.O'Donnell, D.Neudecker, A.E.Lovell, R.C.Haight, C.Y.Wu, R.Henderson, T.Kawano, E.A.Bennett, S.M.Mosby, J.L.Ullmann, N.Fotiades, J.Henderson, T.N.Taddeucci, H.Y.Lee, P.Talou, M.C.White

Measurement of the 235U(n, f) prompt fission neutron spectrum from 10 keV to 10 MeV induced by neutrons of energy from 1 MeV to 20 MeV

NUCLEAR REACTIONS 235U(n, F), E=0.01-10 MeV; measured In, En, neutron time-of-flight, fission fragments, neutrons angular distributions, (fragment)n-coin; deduced prompt fission neutron spectrum (PFNS), components corresponding to first-, second-, and third-chance fission as well as pre-equilibrium neutron emission preceding fission, mean PFNS energy, ratio to PFNMS obtained in 239Pu(n, F) reaction. Experiment performed as a part of Chi-Nu project aimed to measure the PFNS of major actinides with the Weapons Neutron Research (WNR) facility at the Los Alamos Neutron Science Center (LANSCE). The results are compared with other experimental data, CGMF calculations and selected nuclear data evaluations - ENDF/B-VIII.0, JEFF-3.3, JENDL-5.0.

doi: 10.1103/PhysRevC.105.044615
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2022LO09      Phys.Rev. C 106, 014305 (2022)

A.E.Lovell, A.T.Mohan, T.M.Sprouse, M.R.Mumpower

Nuclear masses learned from a probabilistic neural network

ATOMIC MASSES Z=20-110, N=16-160; calculated atomic masses and S(n) using the probabilistic Mixture Density Network (MDN) for six models: M2, MS2, MS6, MS8, MS10, and MS12, and compared with evaluated atomic masses in AME2016 and theoretical masses in Moller's FRDM2012. Relevance to accuracy of the match to the training data, and providing physically meaningful extrapolations beyond the limits of experimental data.

doi: 10.1103/PhysRevC.106.014305
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2022MU14      Phys.Rev. C 106, L021301 (2022)

M.R.Mumpower, T.M.Sprouse, A.E.Lovell, A.T.Mohan

Physically interpretable machine learning for nuclear masses

ATOMIC MASSES 137,138,139,140,141,142,143,144,145,146,147,148,149,150,151,152,153,154,155,156,157,158,159,160,161,162Nd; calculated masses. Results obtained with probabilistic machine learning algorithm. Comparison to AME2016.

doi: 10.1103/PhysRevC.106.L021301
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2022OK02      J.Nucl.Sci.Technol.(Tokyo) 59, 96 (2022)

S.Okumura, T.Kawano, A.E.Lovell, T.Yoshida

Energy Dependent Calculations of Fission Product, Prompt, and Delayed Neutron Yields for Neutron Induced Fission on 235U, 238U, and 239Pu

NUCLEAR REACTIONS 235,238U, 239Pu(n, F), E<5 MeV; calculated neutron multiplicity (nubar), cumulative fission product yield, delayed neutron yield. The Hauser-Feshbach Fission Fragment Decay (HF3D) model. Comparison with experimental data.

doi: 10.1080/00223131.2021.1954103
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2022SC17      J.Phys.(London) G49, 110502 (2022)

H.Schatz, A.D.Becerril Reyes, A.Best, E.F.Brown, K.Chatziioannou, K.A.Chipps, C.M.Deibel, R.Ezzeddine, D.K.Galloway, C.J.Hansen, F.Herwig, A.P.Ji, M.Lugaro, Z.Meisel, D.Norman, J.S.Read, L.F.Roberts, A.Spyrou, I.Tews, F.X.Timmes, C.Travaglio, N.Vassh, C.Abia, P.Adsley, S.Agarwal, M.Aliotta, W.Aoki, A.Arcones, A.Aryan, A.Bandyopadhyay, A.Banu, D.W.Bardayan, J.Barnes, A.Bauswein, T.C.Beers, J.Bishop, T.Boztepe, B.Cote, M.E.Caplan, A.E.Champagne, J.A.Clark, M.Couder, A.Couture, S.E.de Mink, S.Debnath, R.J.deBoer, J.den Hartogh, P.Denissenkov, V.Dexheimer, I.Dillmann, J.E.Escher, M.A.Famiano, R.Farmer, R.Fisher, C.Frohlich, A.Frebel, C.Fryer, G.Fuller, A.K.Ganguly, S.Ghosh, B.K.Gibson, T.Gorda, K.N.Gourgouliatos, V.Graber, M.Gupta, W.C.Haxton, A.Heger, W.R.Hix, W.C.G.Ho, E.M.Holmbeck, A.A.Hood, S.Huth, G.Imbriani, R.G.Izzard, R.Jain, H.Jayatissa, Z.Johnston, T.Kajino, A.Kankainen, G.G.Kiss, A.Kwiatkowski, M.La Cognata, A.M.Laird, L.Lamia, P.Landry, E.Laplace, K.D.Launey, D.Leahy, G.Leckenby, A.Lennarz, B.Longfellow, A.E.Lovell, W.G.Lynch, S.M.Lyons, K.Maeda, E.Masha, C.Matei, J.Merc, B.Messer, F.Montes, A.Mukherjee, M.R.Mumpower, D.Neto, B.Nevins, W.G.Newton, L.Q.Nguyen, K.Nishikawa, N.Nishimura, F.M.Nunes, E.O'Connor, B.W.O'Shea, W.-J.Ong, S.D.Pain, M.A.Pajkos, M.Pignatari, R.G.Pizzone, V.M.Placco, T.Plewa, B.Pritychenko, A.Psaltis, D.Puentes, Y.-Z.Qian, D.Radice, D.Rapagnani, B.M.Rebeiro, R.Reifarth, A.L.Richard, N.Rijal, I.U.Roederer, J.S.Rojo, J.S K, Y.Saito, A.Schwenk, M.L.Sergi, R.S.Sidhu, A.Simon, T.Sivarani, A.Skuladottir, M.S.Smith, A.Spiridon, T.M.Sprouse, S.Starrfield, A.W.Steiner, F.Strieder, I.Sultana, R.Surman, T.Szucs, A.Tawfik, F.Thielemann, L.Trache, R.Trappitsch, M.B.Tsang, A.Tumino, S.Upadhyayula, J.O.Valle Martinez, M.Van der Swaelmen, C.Viscasillas Vazquez, A.Watts, B.Wehmeyer, M.Wiescher, C.Wrede, J.Yoon, R.G.T.Zegers, M.A.Zermane, M.Zingale, the Horizon 2020 Collaborations

Horizons: nuclear astrophysics in the 2020s and beyond

doi: https://dx.doi.org/10.1088/1361-6471/ac8890
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2021CA29      Phys.Rev. C 104, 064611 (2021)

M.Catacora-Rios, G.B.King, A.E.Lovell, F.M.Nunes

Statistical tools for a better optical model

NUCLEAR REACTIONS 48Ca(p, p), E=9, 65 MeV; analyzed experimental data for parameter posterior distributions, σ(θ, E), parameter sensitivities using surface and volume models; deduced depth, radius, and diffuseness of the real part of the optical potential. 48Ca(polarized p, p), E=12, 21 MeV; analyzed experimental data for differential σ(E), analyzing powers iT11, sensitivity matrix. 48Ca(n, n), (polarized n, n), E=12 MeV; 48Ca(p, p), (polarized p, p), E=12, 14, 21 MeV; 208Pb(p, p), (polarized p, p), E=30, 61 MeV; 208Pb(n, n), (polarized n, n), E=30 MeV; analyzed experimental data for ratio between the Bayesian evidence using polarization data over that with cross section data. Analysis of experimental data used three statistical tools: the principal component analysis, the sensitivity analysis based on derivatives, and the Bayesian evidence for optical potential parameters. Relevance to the goal of constraining the optical potential.

doi: 10.1103/PhysRevC.104.064611
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2021KA34      Phys.Rev. C 104, 014611 (2021)

T.Kawano, S.Okumura, A.E.Lovell, I.Stetcu, P.Talou

Influence of nonstatistical properties in nuclear structure on emission of prompt fission neutrons

NUCLEAR REACTIONS 235U(n, F), E=thermal; calculated prompt fission E(n), I(n), individual contribution from each fission fragment to prompt fission neutron spectrum (PFNS) using Hauser-Feshbach fission-fragment decay (HF3D) model. Comparison with experimental data.

doi: 10.1103/PhysRevC.104.014611
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2021LO01      J.Phys.(London) G48, 014001 (2021)

A.E.Lovell, F.M.Nunes, M.Catacora-Rios, G.B.King

Recent advances in the quantification of uncertainties in reaction theory

NUCLEAR REACTIONS 40Ca(n, n), (n, p), (p, p), (d, d), E=11.9-30 MeV; analyzed available data; deduced different optimization schemes used to constrain the optical potential from σ(θ), uncertainties propagation.

doi: 10.1088/1361-6471/abba72
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2021LO02      Phys.Rev. C 103, 014615 (2021)

A.E.Lovell, T.Kawano, S.Okumura, I.Stetcu, M.R.Mumpower, P.Talou

Extension of the Hauser-Feshbach fission fragment decay model to multichance fission

NUCLEAR REACTIONS 235U(n, F), E=0-20 MeV; calculated multichance fission probabilities, average excitation energy causing fission for first-, second-, third-, and fourth-chance fission, pre-neutron-emission mass yields, total kinetic energy (TKE) and average prompt neutron and γ-ray multiplicities as function of incident neutron energy, average neutron multiplicity as a function of fragment mass, prompt fission γ-ray spectrum, independent and cumulative fission mass yields, average number of delayed neutrons emitted in fission. Extended deterministic Hauser-Feshbach fission fragment decay model (HF3D) within the code BeoH to calculate prompt and delayed particle emission from fission fragments. Comparison with experimental data.

doi: 10.1103/PhysRevC.103.014615
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2021MA54      Phys.Rev. C 104, 024602 (2021)

S.Marin, M.S.Okar, E.P.Sansevero, I.E.Hernandez, C.A.Ballard, R.Vogt, J.Randrup, P.Talou, A.E.Lovell, I.Stetcu, O.Serot, O.Litaize, A.Chebboubi, S.D.Clarke, V.A.Protopopescu, S.A.Pozzi

Structure in the event-by-event energy-dependent neutron-γ multiplicity correlations in 252Cf(sf)

RADIOACTIVITY 252Cf(SF); analyzed Eγ and E(n) data collected at the Chi-Nu array at the Los Alamos Neutron Science Center with the application of the normalized differential multiplicity covariances; deduced neutron-γ correlations, evidence for enhancements in neutron-γ correlations around Eγ=0.7 and 1.2 MeV. Comparison with model calculations. Relevance to disagreement in the literature about correlations between neutron-γ competition and fragment properties.

doi: 10.1103/PhysRevC.104.024602
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2021NE06      Phys.Rev. C 104, 034611 (2021)

D.Neudecker, O.Cabellos, A.R.Clark, M.J.Grosskopf, W.Haeck, M.W.Herman, J.Hutchinson, T.Kawano, A.E.Lovell, I.Stetcu, P.Talou, S.Vander Wiel

Informing nuclear physics via machine learning methods with differential and integral experiments

NUCLEAR REACTIONS 238U(n, n'), E=14 MeV; analyzed pulsed-sphere neutron-leakage experimental spectrum obtained at LLNL facility, and compared with evaluated data in ENDF/B-VIII.0. 241Pu(n, F), E=0.1-1.0, 14 MeV; analyzed differential and integral experimental data for fission σ(E) by combining experimental σ data, nuclear-physics theory and neutron-transport simulations of the experiments using machine learning (ML) random forest algorithm and expert judgment. Relevance to improvement of description of nuclear-physics observables in particular application areas.

doi: 10.1103/PhysRevC.104.034611
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2021ST18      Phys.Rev.Lett. 127, 222502 (2021)

I.Stetcu, A.E.Lovell, P.Talou, T.Kawano, S.Marin, S.A.Pozzi, A.Bulgac

Angular Momentum Removal by Neutron and γ-Ray Emissions during Fission Fragment Decays

NUCLEAR REACTIONS 235U, 239Pu(n, F), E thermal; 238U(n, F), E=1.9 MeV; analyzed available data; deduced the angular momentum removal from fission fragments through neutron and γ-ray emission, wide angular momentum removal distributions can hide any underlying correlations in the fission fragment initial spin values.

RADIOACTIVITY 252Cf(SF); analyzed available data; deduced the angular momentum removal from fission fragments through neutron and γ-ray emission.

doi: 10.1103/PhysRevLett.127.222502
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2021TA33      Comput.Phys.Commun. 269, 108087 (2021)

P.Talou, I.Stetcu, P.Jaffke, M.E.Rising, A.E.Lovell, T.Kawano

Fission fragment decay simulations with the CGMFcode

RADIOACTIVITY 252Cf(SF); calculated fission fragment mass yields.

NUCLEAR REACTIONS 235U(n, F), E=0.0000000253, 2, 5 MeV; calculated fission fragment mass yields.

doi: 10.1016/j.cpc.2021.108087
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2020KE05      Phys.Rev. C 102, 034615 (2020)

K.J.Kelly, M.Devlin, J.M.O'Donnell, J.A.Gomez, D.Neudecker, R.C.Haight, T.N.Taddeucci, S.M.Mosby, H.Y.Lee, C.Y.Wu, R.Henderson, P.Talou, T.Kawano, A.E.Lovell, M.C.White, J.L.Ullmann, N.Fotiades, J.Henderson, M.Q.Buckner

Measurement of the 239Pu(n, f) prompt fission neutron spectrum from 10 keV to 10 MeV induced by neutrons of energy 1-20 MeV

NUCLEAR REACTIONS 239Pu(n, F), E=1-20 MeV; measured outgoing prompt fission neutron spectrum (PFNS) in the range of E(n)=0.01-10 MeV, I(n) using Li-glass detector array and 54-detector EJ-309 liquid scintillator array in Chi-Nu experiment at the WNR-LANSCE-Los Alamos facility; deduced correlation matrix for PFNS from the Li-glass and the liquid scintillator. Comparison of present PFNS results with previous experimental results, and with evaluated data in ENDF/B-VIII.0 and JEFF-3.3 libraries.

doi: 10.1103/PhysRevC.102.034615
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Data from this article have been entered in the EXFOR database. For more information, access X4 dataset14682.

2020LO08      Phys.Rev. C 102, 024621 (2020)

A.E.Lovell, P.Talou, I.Stetcu, K.J.Kelly

Correlations between fission fragment and neutron anisotropies in neutron-induced fission

NUCLEAR REACTIONS 235,238U, 239Pu(n, F), E=0-20 MeV; calculated anisotropic angular distributions for fission-fragments, prompt neutrons only from fission, and all prompt neutrons as a function of incident energy, ratio between the neutron anisotropy and the fission-fragment anisotropy. Comparison between the Hauser-Feshbach Monte Carlo calculations using CGMF code, and preliminary experimental data from the Chi-Nu liquid scintillator array at LANL.

doi: 10.1103/PhysRevC.102.024621
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2020LO14      J.Phys.(London) G47, 114001 (2020)

A.E.Lovell, A.T.Mohan, P.Talou

Quantifying uncertainties on fission fragment mass yields with mixture density networks

RADIOACTIVITY 252Cf(SF); calculated fission yields distributions and uncertainties. The mixture density network (MDN).

doi: 10.1088/1361-6471/ab9f58
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2019CA29      Phys.Rev. C 100, 064615 (2019)

M.Catacora-Rios, G.B.King, A.E.Lovell, F.M.Nunes

Exploring experimental conditions to reduce uncertainties in the optical potential

NUCLEAR REACTIONS 48Ca(n, n), E=12, 14 MeV; 48Ca(p, p), E=12, 14, 21, 24, MeV; 48Ca(d, p), E=21 MeV; 208Pb(n, n), E=30, 32 MeV; 208Pb(p, p), E=30, 32, 35, 61, 65 MeV; 208Pb(d, p), E=61 MeV; analyzed mock data generated from a global optical potential, and real experimental data for differential σ(θ, E) and total σ(E) using Markov-chain Monte Carlo Bayesian approach and the three-body model ADWA for the reaction with the selection of different experimental conditions such as ranges of angular distributions, neighboring incident energies, and reducing the experimental uncertainties to investigate effects on the uncertainties of the optical model parameters. Relevance to uncertainty quantification (UQ) in the design of future experiments.

doi: 10.1103/PhysRevC.100.064615
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2019KE04      Phys.Rev.Lett. 122, 072503 (2019)

K.J.Kelly, T.Kawano, J.M.O'Donnell, J.A.Gomez, M.Devlin, D.Neudecker, P.Talou, A.E.Lovell, M.C.White, R.C.Haight, T.N.Taddeucci, S.M.Mosby, H.Y.Lee, C.Y.Wu, R.Henderson, J.Henderson, M.Q.Buckner

Preequilibrium Asymmetries in the 239Pu(n, f) Prompt Fission Neutron Spectrum

NUCLEAR REACTIONS 239Pu(n, F), E=15-17.5 MeV; measured reaction products, En, In; deduced neutron excess of the preequilibrium prefission distribution above the postfission neutron spectrum. Comparison with theoretical calculations.

doi: 10.1103/PhysRevLett.122.072503
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2019KI05      Phys.Rev.Lett. 122, 232502 (2019)

G.B.King, A.E.Lovell, L.Neufcourt, F.M.Nunes

Direct Comparison between Bayesian and Frequentist Uncertainty Quantification for Nuclear Reactions

NUCLEAR REACTIONS 48Ca, 90Zr, 208Pb(p, p), (n, n), E<35 MeV; analyzed available data; deduced σ(θ).

doi: 10.1103/PhysRevLett.122.232502
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2019LO14      Phys.Rev. C 100, 054610 (2019)

A.E.Lovell, I.Stetcu, P.Talou, G.Rusev, M.Jandel

Prompt neutron multiplicity distributions inferred from γ-ray and fission fragment energy measurements

RADIOACTIVITY 252Cf(SF); calculated total γ-ray energy as a function of total fragment kinetic energy (TKE) before and after neutron emission, and for events where the total number of prompt neutrons emitted is zero, two, and four, prompt neutron multiplicity distribution P(ν) using a novel method to extract the neutron multiplicity distribution from correlation plots of the total γ-ray energy and the total fission fragment kinetic energy (TKE), without measuring neutrons. Comparison with calculations using CGMF computer code.

NUCLEAR REACTIONS 235U(n, F), E=thermal; calculated total γ-ray energy as a function of total fragment kinetic energy (TKE) using novel method to extract the neutron multiplicity distributions. Comparison with calculations using CGMF computer code.

doi: 10.1103/PhysRevC.100.054610
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2018JA14      Phys.Rev. C 98, 024609 (2018)

M.I.Jaghoub, A.E.Lovell, F.M.Nunes

Exploration of the energy dependence of proton nonlocal optical potentials

NUCLEAR REACTIONS 40Ca, 90Zr, 208Pb(p, p), E=10-45 MeV; analyzed σ(θ, E); deduced best fit for angular distributions over the whole mass range using both the energy dependent and energy independent Tian, Pang, and Ma nonlocal interactions. 32S, 68Zn, 89Y, 100Mo, 110Pd(p, p), E=10-65 MeV; calculated σ(θ, E) using global interaction parametrization. Comparison with experimental values.

doi: 10.1103/PhysRevC.98.024609
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2018KI14      Phys.Rev. C 98, 044623 (2018)

G.B.King, A.E.Lovell, F.M.Nunes

Uncertainty quantification due to optical potentials in models for (d, p) reactions

NUCLEAR REACTIONS 48Ca(p, p), E=12, 25 MeV; 90Zr(p, p), E=9.018, 12.7, 22.5 MeV; 208Pb(p, p), E=16, 35 MeV; 48Ca, 90Zr(d, d), E=23.2 MeV; 208Pb(d, d), E=28.8 MeV; 48Ca(n, n), E=12 MeV; 90Zr(n, n), E=10, 24 MeV; 208Pb(n, n)=16.9 MeV; analyzed experimental differential σ(E, θ) with uncorrelated and correlated χ2. 90Zr(d, p), E=22.7 MeV; 48Ca(d, p), E=19.3 MeV; 208Pb(d, p), E=32.9 MeV; analyzed differential σ(θ) data with confidence bands using distorted wave Born approximation (DWBA) and adiabatic wave approximation (ADWA) methods; deduced best-fit parameters, and that the uncertainties arising from the optical potentials, constrained by all relevant elastic-scattering channels are large.

doi: 10.1103/PhysRevC.98.044623
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2018LO13      Phys.Rev. C 97, 064612 (2018)

A.E.Lovell, F.M.Nunes

Constraining transfer cross sections using Bayes' theorem

NUCLEAR REACTIONS 48Ca(p, p), E=14.08, 21.0, 25.0 MeV; 48Ca(n, n), E=12.0 MeV; 48Ca(d, d), E=23.2 MeV; 90Zr(p, p), E=12.7, 22.5, 40.0 MeV; 90Zr(n, n), E=24.0 MeV 90Zr(d, d), E=23.2 MeV; 116Sn(p, p), E=22.0, 49.35 MeV; 116Sn(n, n), E=13.9, 24.0 MeV; 208Pb(p, p), E=16.9, 35.0 MeV; 208Pb(n, n), E=16 MeV; 208Pb(d, d), E=28.8; analyzed elastic scattering data; calculated posterior distributions of optical model parameters using Bayes' Theorem. Bayesian methods. 48Ca(d, p), E=24.0 MeV; 90Zr(d, p), E=22.0 MeV; 90Zr(d, n), E=20.0 MeV; 116Sn(d, p), E=44.0 MeV; 208Pb(d, p), E=32.0; calculated differential σ(θ) using adiabatic wave approximation or distorted-wave Born approximation (ADWA, DWBA). Comparison with experimental values.

doi: 10.1103/PhysRevC.97.064612
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2017LO02      Phys.Rev. C 95, 024611 (2017)

A.E.Lovell, F.M.Nunes, J.Sarich, S.M.Wild

Uncertainty quantification for optical model parameters

NUCLEAR REACTIONS 12C(d, d), (d, p), E=11.8 MeV; 90Zr(d, d), (d, p), E=12.0 MeV; 12C(n, n), (n, n'), E=17.29 MeV; 48Ca(n, n), (n, n'), E=7.97 MeV; 54Fe(n, n), (n, n'), E=16.93 MeV; 208Pb(n, n), (n, n'), E=26.0 MeV; analyzed differential σ(θ) data using optical potential method, and two reaction models: coupled-channels Born approximation (CCBA) for elastic- and inelastic-scattering calculations, and distorted-wave Born approximation (DWBA) for elastic scattering and transfer calculations; deduced best fit parameters using uncorrelated and correlated χ2 minimization functions, uncertainty quantification for nuclear theories; concluded that correlated χ2 functions, but with broader confidence bands, provide a more natural and better parameterization of the process.

doi: 10.1103/PhysRevC.95.024611
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2017LO03      Phys.Rev. C 95, 034605 (2017)

A.E.Lovell, F.M.Nunes, I.J.Thompson

Three-body model for the two-neutron emission of 16Be

RADIOACTIVITY 16Be(2n); calculated resonance energy, phase shifts, and density distributions. Three-body calculation in the continuum using hyperspherical harmonics and the R-matrix method with n-14Be interactions for dineutron emission.

doi: 10.1103/PhysRevC.95.034605
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2017LO16      Phys.Rev. C 96, 051601 (2017)

A.E.Lovell, P.-L.Bacq, P.Capel, F.M.Nunes, L.J.Titus

Energy dependence of nonlocal optical potentials

NUCLEAR REACTIONS 208Pb(n, n), E=7.0, 9.0, 11.0, 14.6, 16.9, 20.0, 22.0, 26.0, 30.3, 40.0 MeV; 40Ca(n, n), E=9.9, 11.9, 13.9, 16.9, 21.7, 25.5, 30.1, 40.1 MeV; 90Zr(n, n), E=5.9, 7.0, 8.0, 10.0, 11.0, 24.0 MeV; 27Al(n, n), E=10.159, 18, 26 MeV; 118Sn(n, n), E=11, 14, 18, 24 MeV; analyzed differential σ(θ, E) data; deduced two new parametrizations by including energy dependence in the original nonlocal Perey and Buck (PB) and Tian, Pang, and Ma (TPM) potentials.

doi: 10.1103/PhysRevC.96.051601
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2015LO03      J.Phys.(London) G42, 034014 (2015)

A.E.Lovell, F.M.Nunes

Systematic uncertainties in direct reaction theories

doi: 10.1088/0954-3899/42/3/034014
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