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241 results on '"Bleuel, D."'

202. La 137 , 138 , 139 ( n , γ ) cross sections constrained with statistical decay properties of La 138 , 139 , 140 nuclei

Author

Kheswa, B. V., Wiedeking, M., Brown, J. A., Larsen, A. C., Goriely, S., Guttormsen, M., Bello Garrote, F. L., Bernstein, L. A., Bleuel, D. L., Eriksen, T. K., Giacoppo, F., Görgen, A., Goldblum, B. L., Hagen, T. W., Koehler, P. E., Klintefjord, M., Malatji, K. L., Midtbø, J. E., Nyhus, H. T., Papka, P., Renstrøm, T., Rose, S. J., Sahin, E., Siem, S., and Tornyi, T. G.

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203. EXOTIC NUCLEI RESEARCH AT LLNL

Author

Stoyer, M. A., Ahle, L. E., Becker, J. A., Bernstein, L. A., Bleuel, D. L., Burke, J. T., Casperson, R. J., Perry Chodash, Chyzh, A., Czeszumska, A., Kwan, E., Moran, M. J., Norman, E. B., Padgett, S. W., Pedretti, M., Ressler, J. J., Sayre, D. B., Scielzo, N. D., Sheets, S. A., Stoeffl, W., Tonchev, A. P., Wang, B. S., Wu, C. Y., Yee, R. M., Penionzhkevich, Yu E., and Sobolev, Yu G.

204. Neutron transfer in the 13C + 197Au reaction from gold isotope residuals.

Author

Daub, B. H., Bleuel, D. L., Wiedeking, M., Bernstein, L. A., Brickner, N. M., Brown, J. A., Goldblum, B. L., Holliday, K. S., Lundgren, J., and Moody, K.

Subjects
*GOLD isotopes, *NEUTRONS, *EVAPORATION model (Nuclear physics)
Abstract

Residual gold nuclei were produced via neutron transfer at multiple energies using a 130-MeV 13C beam incident on a stacked-foil target consisting of alternating layers of 197Au and 27Al. Production cross sections, over an energy range of 56 to 129 MeV, for seven gold isotopes and two gold isomers were determined through activation analysis. By using the Wilczyński binary transfer model with a modified version of the recoil formula and a standard evaporation model, we were able to reproduce the isotopic production cross sections at high beam energy, with some disagreement at lower beam energies. This limiting angular momentum model does not predict the transfer of sufficient angular momentum to reproduce the observed isomeric populations. [ABSTRACT FROM AUTHOR]

Published
2017
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207. Level densities of 74,76Ge from compound nuclear reactions.

Author

Voinov, A. V., Renstrøm, T., Bleuel, D. L., Grimes, S. M., Guttormsen, M., Larsen, A. C., Liddick, S. N., Perdikakis, G., Spyrou, A., Akhtar, S., Alanazi, N., Brandenburg, K., Brune, C. R., Danley, T. W., Dhakal, S., Gastis, P., Giri, R., Massey, T. N., Meisel, Z., and Nikas, S.

Subjects
*ENERGY level densities, *SPECTRUM analysis, *NUCLEAR reactions, *DENSITY
Abstract

The level densities of 74,76Ge nuclei are studied with 68,70Zn(7Li,Xp) reactions. Proton evaporation spectra are measured at backward angles in a wide energy region, from about 2 to 25 MeV. The analysis of spectra allows for the testing of level density models used in modern reaction codes for practical cross-section calculations. Our results show that at excitation energies above the discrete level region, all level density models tested in this work overestimate the level densities that are needed to reproduce proton spectra from these reactions. The Gilbert and Cameron model, which includes the constant-temperature energy dependence of the level density, shows the best agreement with experiment, however, its parameters need to be adjusted to reflect the observed reduction of the level density at higher excitation energies. [ABSTRACT FROM AUTHOR]

Published
2019
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208. Decay spectroscopy of element 115 daughters: 280Rg →276Mt and 276Mt → 272Bth.

Author

Gates, J. M., Gregorich, K. E., Gothe, O. R., Uribe, E. C., Pang, G. K., Bleuel, D. L., Block, M., Clark, R. M., Campbell, C. M., Crawford, H. L., Cromaz, M., Di Nitto, A., Düllmann, Ch. E., Esker, N. E., Fahlander, C., Fallon, P., Farjadi, R. M., Forsberg, U., Khuyagbaatar, J., and Loveland, W.

Subjects
*DECAY chains, *SUPERHEAVY elements, *SPONTANEOUS fission, *X-ray spectroscopy, *COMPTON scattering, FLEROV Laboratory of Nuclear Reactions (Dubna, Russia)
Abstract

Forty-six decay chains, assigned to the decay of 288115, were produced using the 243Am)(48,3n)288115 reaction at the Lawrence Berkeley National Laboratory 88-in. cyclotron. The resulting series of α decays were studied using α-photon and α-x-ray spectroscopies. Multiple α-photon coincidences were observed in the element 115 decay chain members, particularly in the third- and fourth-generation decays (presumed to be 280Rg and 276Mt, respectively). Upon combining these data with those from 22 288115 decay chains observed in a similar experiment, updated level schemes in 276Mt and 272Bh (populated by the α decay of 280Rg and 276Mt, respectively) are proposed. Photons were observed in the energy range expected for K x rays coincident with the α decay of both 280Rg and 276Mt. However, Compton scattering of higher-energy γ rays and discrete transitions are present in the K x-ray region preventing a definitive Z identification to be made based on observation of characteristic K x-ray energies. [ABSTRACT FROM AUTHOR]

Published
2015
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209. γ decay from the quasicontinuum of l97,198Au.

Author

Giacoppo, F., Garrote, F. L. Bello, Bernstein, L. A., Bleuel, D. L., Firestone, R. B., Görgen, A., Guttormsen, M., Hagen, T. W., Klintefjord, M., Koehler, P. E., Larsen, A. C., Nyhus, H. T., Renstrøm, T., Sahin, E., Siem, S., and Tornyi, T.

Subjects
*PARTICLE decays, *FIELD theory (Physics), *MAGNETIC dipoles, *NUCLEAR spin, *ISOTOPES
Abstract

The average electromagnetic dipole response of levels in the quasicontinuum of 197,198Au has been measured using (³He,³He') and (d,p) reactions. The extracted y-ray strength functions have been normalized according to three model assumptions for the nuclear spin distribution. An enhancement in the energy region Eγ = 3.0-6.5 MeV is observed for both isotopes. The EI component of such excess of strength is studied in detail for 198Au and is interpreted as the pygmy dipole resonance with an energy centroid of 5.9(1) MeV and exhausts about 1% of the total integrated strength. The pygmy dipole resonance is shown to have a significant impact on the calculated 197Au(n,γ)198Au cross section. [ABSTRACT FROM AUTHOR]

Published
2015
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210. Spectroscopy of 153Gd and 157Gd using the (p,dɣ) reaction.

Author

Ross, T. J., Hughes, R. O., Allmond, J. M., Beausang, C. W., Angell, C. T., Basunia, M. S., Bleuel, D. L., Burke, J. T., Casperson, R. J., Escher, J. E., Fallon, P., Hatarik, R., Munson, J., Paschalis, S., Petri, M., Phair, L. W., Ressler, J. J., and Scielzo, N. D.

Subjects
*NUCLEAR physics, *GADOLINIUM, *NUCLEAR reactions, *PARTICLE interactions, *EXCITATION energy (In situ microanalysis)
Abstract

Low-spin single quasineutron levels in 153Gd and 157Gd have been studied following the 154Gd(p,d-ɣ)153Gd and 158Gd(p,d-ɣ)157Gd reactions. A combined Si telescope and high-purity germanium array was utilized, allowing d-ɣ and d-ɣ-ɣ coincidence measurements. Almost all of the established low-excitation-energy, low-spin structures were confirmed in both 153Gd and 157Gd. Several new levels and numerous new ɣ rays are observed in both nuclei, particularly for Ex≥1 MeV. Residual effects of a neutron subshell closure at N=64 are observed in the form of a large excitation energy gap in the single quasineutron level schemes. [ABSTRACT FROM AUTHOR]

Published
2014
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211. Remnants of spherical shell structures in deformed nuclei: The impact of an N = 64 neutron subshell closure on the structure of N ≈ 90 gadolinium nuclei.

Author

Ross, T. J., Hughes, R. O., C. W. Beausang, Allmond, J. M., Angell, C. T., Basunia, M. S., Bleuel, D. L., Burke, J. T., Casperson, R. J., Escher, J. E., Fallon, P., Hatarik, R., Munson, J., Paschalis, S., Petri, M., Phair, L. W., Ressler, J. J., and Scielzo, N. D.

Subjects
*SPHERICAL shells (Engineering), *NEUTRONS, *PROTONS, *DEFORMATIONS (Mechanics), GADOLINIUM isotopes
Abstract

Odd-mass gadolinium isotopes around N = 90 were populated by the (p,d) reaction, utilizing 25-MeV protons, resulting in population of low-spin quasineutron states at energies near and below the Fermi surface. Systematics of the single quasineutron levels populated are presented. A large excitation energy gap is observed between levels originating from the 2d3/2, 1ft 11/2, and 3j1/2 spherical parents (above the N = 64 gap), and the 2(below the gap), indicating that the spherical shell model level spacing is maintained at least to moderate deformations. [ABSTRACT FROM AUTHOR]

Published
2013
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212. Measurement of the T+T Neutron Spectrum Using the National Ignition Facility.

Author

Sayre, D. B., Brune, C. R., Caggiano, J. A., Glebov, V. Y., Hatarik, R., Bacher, A. D., Bleuel, D. L., Casey, D. T., Cerjan, C. J., Eckart, M. J., Fortner, R. J., Frenje, J. A., Friedrich, S., Gatu-Johnson, M., Grim, G. P., Hagmann, C., Knauer, J. P., Kline, J. L., McNabb, D. P., and McNaney, J. M.

Subjects
*NEUTRON measurement, *TRITIUM, *INERTIAL confinement fusion, *GROUND state (Quantum mechanics), *FERMION decay, *EXPERIMENTS
Abstract

Neutron time-of-flight spectra from inertial confinement fusion experiments with tritium-filled targets have been measured at the National Ignition Facility. These spectra represent a significant improvement in energy resolution and statistics over previous measurements, and afford the first definitive observation of a peak resulting from sequential decay through the ground state of 5He at low reaction energies Ec.m.≲100  keV. To describe the spectrum, we have developed an R-matrix model that accounts for interferences from fermion symmetry and intermediate states, and show these effects to be non-negligible. We also find the spectrum can be described by sequential decay through ℓ=1 states in 5He, which differs from previous interpretations. [ABSTRACT FROM AUTHOR]

Published
2013
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213. Statistical y rays in the analysis of surrogate nuclear reactions.

Author

Scielzo, N. D., Escher, J. E., Allmond, J. M., Basunia, M. S., Beausang, C. W., Bernstein, L. A., Bleuel, D. L., Burke, J. T., Clark, R. M., Dietrich, F. S., Fallon, P., Gibelin, J., Goldblum, B. L., Lesher, S. R., McMahan, M. A., Norman, E. B., Phair, L., Rodriguez-Vieitez, E., Sheets, S. A., and Thompson, I. J.

Subjects
*STATISTICAL physics, *NUCLEAR reactions, *NUCLEAR cross sections, *RADIOISOTOPES, *RADIOACTIVE decay, *PROTON scattering, *RELAXATION phenomena
Abstract

The surrogate nuclear reaction method is being applied in many efforts to indirectly determine neutron-induced reaction cross sections on short-lived isotopes. This technique aims to extract accurate (n,y) cross sections from measured decay properties of the compound nucleus of interest (created using a different reaction). The advantages and limitations of a method that identifies the y-ray decay channel by detecting any high-energy ("statistical") y ray emitted during the relaxation of the compound nucleus were investigated. Data collected using the Silicon Telescope Array for Reaction Studies and Livermore-Berkeley Array for Collaborative Experiments silicon and germanium detector arrays were used to study the decay of excited gadolinium nuclei following inelastic proton scattering. In many cases, this method of identifying the y-ray decay channel can simplify the experimental data collection and greatly improve the detection efficiency for y-ray cascades. The results show sensitivity to angular-momentum differences between the surrogate reaction and the desired (n,y) reaction similar to an analysis performed using low-lying discrete transitions even when ratios of cross sections are considered. [ABSTRACT FROM AUTHOR]

Published
2012
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214. Low-Energy Enhancement in the Photon Strength of 95 Mo.

Author

Wiedeking, M., Bernstein, L. A., Krticka, M., Bleuel, D. L., Allmond, J. M., Basunia, M. S., Burke, J. T., Fallon, P., Firestone, R. B., Goldblum, B. L., Hatarik, R., Lake, P. T., Lee, I-Y., Lesher, S. R., Paschalis, S., Petri, M., Phair, L., and Scielzo, N. D.

Subjects
*NUCLEAR physics, *NUCLEAR energy, *RADIOACTIVE decay, *NUCLEAR excitation, *QUASIPARTICLES, *NUCLEAR counters
Abstract

A new experimental technique is presented using proton-y-y correlations from '"Mofd, pf5Mo reactions which allows for the model-independent extraction of the photon strength function at various excitation energies using primary y-ray decay from the quasicontinuum to individual low-lying levels. Detected particle energies provide the entrance excitation energies into the residual nucleus while y-ray transitions from low-lying levels specify the discrete states being fed. Results strongly support the existence of the previously reported low-energy enhancement in the photon strength function. [ABSTRACT FROM AUTHOR]

Published
2012
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215. Surrogate measurement of the 238Pu(n,f) cross section.

Author

Ressler, J. J., Burke, J. T., Escher, J. E., Angell, C. T., Basunia, M. S., Beausang, C. W., Bernstein, L. A., Bleuel, D. L., Casperson, R. J., Goldblum, B. L., Gostic, J., Hatarik, R., Henderson, R., Hughes, R. O., Munson, J., Phair, L. W., Ross, T. J., Scielzo, N. D., Swanberg, E., and Thompson, I. J.

Subjects
*NEUTRON-proton interactions, *INELASTIC scattering, *NUCLEAR fission, *NUCLEAR cross sections, *NEUTRON beams, *ENERGY policy
Abstract

The neutron-induced fission cross section of 238Pu was determined using the surrogate ratio method. The (n,f) cross section over an equivalent neutron energy range 5-20 MeV was deduced from inelastic α-induced fission reactions on 239Pu, with 235U(α,α′f) and 236U(α,α′f) used as references. These reference reactions reflect 234U(n,f) and 235U(n,f) yields, respectively. The deduced 238Pu(n,f) cross section agrees well with standard data libraries up to ~10 MeV, although larger values are seen at higher energies. The difference at higher energies is less than 20%. [ABSTRACT FROM AUTHOR]

Published
2011
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216. 69,71Co β-decay strength distributions from total absorption spectroscopy.

Author

Lyons, S., Spyrou, A., Liddick, S. N., Naqvi, F., Crider, B. P., Dombos, A. C., Bleuel, D. L., Brown, B. A., Couture, A., Campo, L. Crespo, Engel, J., Guttormsen, M., Larsen, A. C., Lewis, R., Möller, P., Mosby, S., Mumpower, M. R., Ney, E. M., Palmisano, A., and Perdikakis, G.

Subjects
*NEUTRON capture, *SILICON detectors, *HEAVY elements, *SPECTROMETRY, *ABSORPTION
Abstract

Background: The rapid neutron capture process is one of the main nucleosynthesis processes of elements heavier than Fe. Uncertainties in nuclear properties, such as masses, half-lives, and β-delayed neutron probabilities can cause orders of magnitude of variation within astrophysical r-process simulations. Presently, theoretical models are used to make global predictions of various nuclear properties for the thousands of nuclei required for these simulations, and measurements are required to benchmark these models, especially far from stability. Purpose: β-decay strength distributions can be used to not only inform astrophysical r-process simulations, but also to provide a stringent test for theoretical calculations. The aim of this work is to provide accurate strength distributions for 69,71Coβ decay. Method: The technique of total absorption spectroscopy was used to measure the β decay of 69,71Co for the first time at the National Superconducting Cyclotron Laboratory. The ions were implanted in a double-sided silicon strip detector at the center of the Summing NaI(Tl) detector and identified using standard particle identification methods. The response of the detection system to the β-decay electron and subsequent γ-ray radiation was fit to the observed experimental data using a χ²-minimization technique. Results: β-feeding intensities and Gamow-Teller strength distributions were extracted from the fits of the experimental data. The β-decay intensities show that there is a large percentage of feeding to levels above 2 MeV, which have not been observed in previous studies. The resultant β-feeding intensities and Gamow-Teller strength distributions were compared to shell model and quasiparticle random phase approximation (QRPA) calculations. Conclusions: Comparing experimentally determined β-decay strength distributions provides a test of models, which are commonly used for global β-decay properties for astrophysical calculations. This work highlights the importance of performing detailed comparisons of models to experimental data, particularly far from stability and as close to the r-process path as possible. [ABSTRACT FROM AUTHOR]

Published
2019
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217. Restricted spin-range correction in the Oslo method: The example of nuclear level density and γ-ray strength function from 239Pu(d, pγ) 240Pu.

Author

Zeiser, F., Tveten, G. M., Potel, G., Larsen, A. C., Guttormsen, M., Laplace, T. A., Siem, S., Bleuel, D. L., Goldblum, B. L., Bernstein, L. A., Garrote, F. L. Bello, Campo, L. Crespo, Eriksen, T. K., Görgen, A., Hadynska-Klek, K., Ingeberg, V. W., Midtbø, J. E., Sahin, E., Tornyi, T., and Voinov, A.

Subjects
*ENERGY level densities, *RADIOACTIVE decay, *NUCLEAR reactions, *GREEN'S functions, *NUCLEAR spin, *TRANSFER functions, *PARITY (Physics), *DEUTERONS
Abstract

The Oslo method has been applied to particle-γ coincidences following the 239Pu(d, p) reaction to obtain the nuclear level density (NLD) and γ-ray strength function (γ SF) of 240Pu. The experiment was conducted with a 12 MeV deuteron beam at the Oslo Cyclotron Laboratory. The low spin transfer of this reaction leads to a spin-parity mismatch between populated and intrinsic levels. This is a challenge for the Oslo method as it can have a significant impact on the extracted NLD and γ SF. We have developed an iterative approach to ensure consistent results even for cases with a large spin-parity mismatch, in which we couple Green's function transfer calculations of the spin-parity dependent population cross-section to the nuclear decay code rainier. The resulting γ SF shows a pronounced enhancement between 2-4 MeV that is consistent with the location of the low-energy orbital M1 scissors mode. [ABSTRACT FROM AUTHOR]

Published
2019
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218. Experimental constraints on the 73Zn (n, γ) 74Zn reaction rate.

Author

Lewis, R., Liddick, S. N., Larsen, A. C., Spyrou, A., Bleuel, D. L., Couture, A., Campo, L. Crespo, Crider, B. P., Dombos, A. C., Guttormsen, M., Mosby, S., Naqvi, F., Perdikakis, G., Prokop, C. J., Quinn, S. J., Renstrøm, T., and Siem, S.

Subjects
*NEUTRON capture, *ENERGY level densities, *SUPERHEAVY elements, *NUCLEAR physics
Abstract

Background: The recent observation of a neutron-star merger finally confirmed one astrophysical location of the rapid neutron-capture process (r-process). Evidence of the production of A < 140 nuclei was seen, but there is still little detailed information about how those lighter elements are produced in such an environment. Many of the questions surrounding the A ≈ 80 nuclei are likely to be answered only when the nuclear physics involved in the production of r-process nuclei is well understood. Neutron-capture reactions are an important component of the r-process, and neutron-capture cross sections of r-process nuclei, which are very neutron rich, have large uncertainties. Purpose: Indirectly determine the neutron-capture cross section and reaction rate of 73 Zn (n, γ) 74 Zn. Methods: The nuclear level density (NLD) and γ -ray strength function (γ SF) of 74 Zn were determined following a total absorption spectroscopy (TAS) experiment focused on the ß decay of 74 Cu into 74 Zn performed at the National Superconducting Cyclotron Laboratory. The NLD and γ SF were used as inputs in a Hauser-Feshbach statistical model to calculate the neutron-capture cross section and reaction rate. Results: The NLD and γ SF of 74 Zn were experimentally constrained for the first time using ß -delayed γ rays measured with TAS and the ß -Oslo method. The NLD and γ SF were then used to constrain the neutron-capture cross section and reaction rate for the 73 Zn (n, γ) 74 Zn reaction. Conclusions: The uncertainty in the neutron-capture cross section and reaction rate of 73 Zn (n, γ) 74 Zn calculated in TALYS was reduced to under a factor of 2 from a factor of 5 in the cross section and a factor of 11 in the reaction rate using the experimentally obtained NLD and γ SF. [ABSTRACT FROM AUTHOR]

Published
2019
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219. First Direct Measurements of Superheavy-Element Mass Numbers.

Author

Gates, J. M., Pang, G. K., Pore, J. L., Gregorich, K. E., Kwarsick, J. T., Savard, G., Esker, N. E., Covo, M. Kireeff, Mogannam, M. J., Batchelder, J. C., Bleuel, D. L., Clark, R. M., Crawford, H. L., Fallon, P., Hubbard, K. K., Hurst, A. M., Kolaja, I. T., Macchiavelli, A. O., Morse, C., and Orford, R.

Subjects
*SUPERHEAVY elements, *MASS (Physics)
Abstract

An experiment was performed at Lawrence Berkeley National Laboratory's 88-in. Cyclotron to determine the mass number of a superheavy element. The measurement resulted in the observation of two α-decay chains, produced via the 243Am(48Ca,xn)291-xMc reaction, that were separated by mass-to-charge ratio (A/q) and identified by the combined BGS+FIONA apparatus. One event occurred at A/q=284 and was assigned to 284Nh (Z=113), the α-decay daughter of 288Mc (Z=115), while the second occurred at A/q=288 and was assigned to 288Mc. This experiment represents the first direct measurements of the mass numbers of superheavy elements, confirming previous (indirect) mass-number assignments. [ABSTRACT FROM AUTHOR]

Published
2018
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220. Enhanced low-energy γ-decay strength of 70Ni and its robustness within the shell model.

Author

Larsen, A. C., Midtbø, J. E., Guttormsen, M., Renstrøm, T., Liddick, S. N., Spyrou, A., Karampagia, S., Brown, B. A., Achakovskiy, O., Kamerdzhiev, S., Bleuel, D. L., Couture, A., Campo, L. Crespo, Crider, B. P., Dombos, A. C., Lewis, R., Mosby, S., Naqvi, F., Perdikakis, G., and Prokop, C. J.

Subjects
*GAMMA decay, *NUCLEAR shell theory, *NEUTRON capture
Abstract

Neutron-capture reactions on very neutron-rich nuclei are essential for heavy-element nucleosynthesis through the rapid neutron-capture process, now shown to take place in neutron-star merger events. For these exotic nuclei, radiative neutron capture is extremely sensitive to their γ-emission probability at very low γ energies. In this work, we present measurements of the γ-decay strength of 70Ni over the wide range 1.3≤Eγ≤8 MeV. A significant enhancement is found in the γ-decay strength for transitions with Eγ<3 MeV. At present, this is the most neutron-rich nucleus displaying this feature, proving that this phenomenon is not restricted to stable nuclei. We have performed E1-strength calculations within the quasiparticle time-blocking approximation, which describe our data above Eγ≃5 MeV very well. Moreover, large-scale shell-model calculations indicate an M1 nature of the low-energy γ strength. This turns out to be remarkably robust with respect to the choice of interaction, truncation, and model space, and we predict its presence in the whole isotopic chain, in particular the neutron-rich 72,74,76Ni. [ABSTRACT FROM AUTHOR]

Published
2018
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221. Energy dependence of the prompt γ-ray emission from the (d,p)-induced fission of 234U* and 240Pu*.

Author

Rose, S. J., Zeiser, F., Wilson, J. N., Oberstedt, A., Oberstedt, S., Siem, S., Tveten, G. M., Bernstein, L. A., Bleuel, D. L., Brown, J. A., Campo, L. Crespo, Giacoppo, F., Görgen, A., Guttormsen, M., Hadyńska, K., Hafreager, A., Hagen, T. W., Klintefjord, M., Laplace, T. A., and Larsen, A. C.

Subjects
*NUCLEAR excitation, *THERMAL neutrons, *PLUTONIUM compounds
Abstract

Prompt-fission γ rays are responsible for approximately 5% of the total energy released in fission, and therefore important to understand when modeling nuclear reactors. In this work we present prompt γ-ray emission characteristics in fission as a function of the nuclear excitation energy of the fissioning system. Emitted γ-ray spectra were measured, and γ-ray multiplicities and average and total γ energies per fission were determined for the 233U(d,pf) reaction for excitation energies between 4.8 and 10 MeV, and for the 239Pu(d,pf) reaction between 4.5 and 9 MeV. The spectral characteristics show no significant change as a function of excitation energy above the fission barrier, despite the fact that an extra ~5 MeV of energy is potentially available in the excited fragments for γ decay. The measured results are compared with model calculations made for prompt γ-ray emission with the fission model code gef. Further comparison with previously obtained results from thermal neutron induced fission is made to characterize possible differences arising from using the surrogate (d,p) reaction. [ABSTRACT FROM AUTHOR]

Published
2017
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222. 137,138,139La (n, γ) cross sections constrained with statistical decay properties of 138,139,140La nuclei.

Author

Kheswa, B. V., Wiedeking, M., Brown, J. A., Larsen, A. C., Goriely, S., Guttormsen, M., Garrote, F. L. Bello, Bernstein, L. A., Bleuel, D. L., Eriksen, T. K., Giacoppo, F., Görgen, A., Goldblum, B. L., Hagen, T. W., Koehler, P. E., Klintefjord, M., Malatji, K. L., Midtbø, J. E., Nyhus, H. T., and Papka, P.

Subjects
*ATOMIC nucleus, *RADIOACTIVE decay
Abstract

The nuclear level densities and γ-ray strength functions of 138,139,140La were measured using the 139La(³He, α), 139La(³He,' ³He), and 139La(d, p) reactions. The particle-γ coincidences were recorded with the silicon particle telescope (SiRi) and NaI(Tl) (CACTUS) arrays. In the context of these experimental results, the low-energy enhancement in the A ~ 140 region is discussed. The 137,138,139La(n, γ) cross sections were calculated at s- and p-process temperatures using the experimentally measured nuclear level densities and γ-ray strength functions. Good agreement is found between 139La (n, γ) calculated cross sections and previous measurements. [ABSTRACT FROM AUTHOR]

Published
2017
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223. Strong Neutron-γ Competition above the Neutron Threshold in the Decay of 70Co.

Author

Spyrou, A., Liddick, S. N., Naqvi, F., Crider, B. P., Dombos, A. C., Bleuel, D. L., Brown, B. A., Couture, A., Campo, L. Crespo, Guttormsen, M., Larsen, A. C., Lewis, R., Möller, P., Mosby, S., Mumpower, M. R., Perdikakis, G., Prokop, C. J., Renstrøm, T., Siem, S., and Quinn, S. J.

Subjects
*CARBON monoxide, *QUASIPARTICLES, *NUCLEAR structure
Abstract

he β-decay intensity of 70Co was measured for the first time using the technique of total absorption spectroscopy. The large β-decay Q value [12.3(3) MeV] offers a rare opportunity to study β-decay properties in a broad energy range. Two surprising features were observed in the experimental results, namely, the large fragmentation of the β intensity at high energies, as well as the strong competition between ? rays and neutrons, up to more than 2 MeV above the neutron-separation energy. The data are compared to two theoretical calculations: the shell model and the quasiparticle random phase approximation (QRPA). Both models seem to be missing a significant strength at high excitation energies. Possible interpretations of this discrepancy are discussed. The shell model is used for a detailed nuclear structure interpretation and helps to explain the observed γ-neutron competition. The comparison to the QRPA calculations is done as a means to test a model that provides global β-decay properties for astrophysical calculations. Our work demonstrates the importance of performing detailed comparisons to experimental results, beyond the simple half-life comparisons. A realistic and robust description of the β-decay intensity is crucial for our understanding of nuclear structure as well as of r-process nucleosynthesis. [ABSTRACT FROM AUTHOR]

Published
2016
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224. Completing the nuclear reaction puzzle of the nucleosynthesis of 92Mo.

Author

Tveten, G. M., Spyrou, A., Schwengner, R., Naqvi, F., Larsen, A. C., Eriksen, T. K., Garrote, F. L. Bello, Bernstein, L. A., Bleuel, D. L., Campo, L. Crespo, Guttormsen, M., Giacoppo, F., Görgen, A., Hagen, T. W., Hadynska-Klek, K., Klintefjord, M., Meyer, B. S., Nyhus, H. T., Renstrøm, T., and Rose, S. J.

Subjects
*MOLYBDENUM compounds, *NUCLEOSYNTHESIS, *NUCLEAR physics
Abstract

One of the greatest questions for modern physics to address is how elements heavier than iron are created in extreme astrophysical environments. A particularly challenging part of that question is the creation of the so-called p-nuclei, which are believed to be mainly produced in some types of supernovae. The lack of needed nuclear data presents an obstacle in nailing down the precise site and astrophysical conditions. In this work, we present for the first time measurements on the nuclear level density and average γ strength function of 92Mo. State-of-the-art p-process calculations systematically underestimate the observed solar abundance of this isotope. Our data provide stringent constraints on the 91Nb(p,γ)92Mo reaction rate, which is the last unmeasured reaction in the nucleosynthesis puzzle of 92Mo. Based on our results, we conclude that the 92Mo abundance anomaly is not due to the nuclear physics input to astrophysical model calculations. [ABSTRACT FROM AUTHOR]

Published
2016
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225. Nature of low-lying electric dipole resonance excitations in 74Ge.

Author

Negi, D., Wiedeking, M., Lanza, E. G., Litvinova, E., Vitturi, A., Bark, R. A., Bernstein, L. A., Bleuel, D. L., Bvumbi, S., Bucher, T. D., Daub, B. H., Dinoko, T. S., Easton, J. L., Görgen, A., Guttormsen, M., Jones, P., Kheswa, B. V., Khumalo, N. A., Larsen, A. C., and Lawrie, E. A.

Subjects
*GERMANIUM compounds, *ISOBARIC spin, *QUASIPARTICLES
Abstract

Isospin properties of dipole excitations in 74Ge are investigated using the (α,α′γ) reaction and compared to (γ,γ′) data. The results indicate that the dipole excitations in the energy region of 6 to 9 MeV adhere to the scenario of the recently found splitting of the region of dipole excitations into two separated parts: one at low energy, being populated by both isoscalar and isovector probes, and the other at high energy, excited only by the electromagnetic probe. Relativistic quasiparticle time blocking approximation (RQTBA) calculations show a reduction in the isoscalar E1 strength with an increase in excitation energy, which is consistent with the measurement. [ABSTRACT FROM AUTHOR]

Published
2016
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226. Experimental Neutron Capture Rate Constraint Far from Stability.

Author

Liddick, S. N., Spyrou, A., Crider, B. P., Naqvi, F., Larsen, A. C., Guttormsen, M., Mumpower, M., Surman, R., Perdikakis, G., Bleuel, D. L., Couture, A., Campo, L. Crespo, Dombos, A. C., Lewis, R., Mosby, S., Nikas, S., Prokop, C. J., Renstrom, T., Rubio, B., and Siem, S.

Subjects
*NEUTRON capture, *NUCLEAR reactions, *NUCLEOSYNTHESIS
Abstract

Nuclear reactions where an exotic nucleus captures a neutron are critical for a wide variety of applications, from energy production and national security, to astrophysical processes, and nucleosynthesis. Neutron capture rates are well constrained near stable isotopes where experimental data are available; however, moving far from the valley of stability, uncertainties grow by orders of magnitude. This is due to the complete lack of experimental constraints, as the direct measurement of a neutron-capture reaction on a short-lived nucleus is extremely challenging. Here, we report on the first experimental extraction of a neutron capture reaction rate on 69Ni, a nucleus that is five neutrons away from the last stable isotope of Ni. The implications of this measurement on nucleosynthesis around mass 70 are discussed, and the impact of similar future measurements on the understanding of the origin of the heavy elements in the cosmos is presented. [ABSTRACT FROM AUTHOR]

Published
2016
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227. Low-energy enhancement in the γ-ray strength functions of 73,74Ge.

Author

Renstrøm, T., Nyhus, H.-T., Utsunomiya, H., Schwengner, R., Goriely, S., Larsen, A. C., Filipescu, D. M., Gheorghe, I., Bernstein, L. A., Bleuel, D. L., Glodariu, T., Görgen, A., Guttormsen, M., Hagen, T. W., Kheswa, B. V., Lui, Y.-W., Negi, D., Ruud, I. E., Shima, T., and Siem, S.

Subjects
*GAMMA rays, *GERMANIUM compounds, *NUCLEAR cross sections
Abstract

The γ-ray strength functions and level densities of 73,74Ge have been extracted up to the neutron-separation energy Sn from particle-γ coincidence data using the Oslo method. Moreover, the γ-ray strength function of 74Ge above Sn has been determined from photoneutron measurements; hence these two experiments cover the range of Eγ≈1-13 MeV for 74Ge. The obtained data show that both 73,74Ge display an increase in strength at low γ energies. The experimental γ-ray strength functions are compared with M1 strength functions deduced from average B(M1) values calculated within the shell model for a large number of transitions. The observed low-energy enhancements in 73,74Ge are adopted in the calculations of the 72,73Ge(n,γ) cross sections, where there are no direct experimental data. Calculated reaction rates for more neutron-rich germanium isotopes are shown to be strongly dependent on the presence of the low-energy enhancement. [ABSTRACT FROM AUTHOR]

Published
2016
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228. Experimentally constrained (p,γ)89Y and (n,γ)89Y reaction rates relevant to p-process nucleosynthesis.

Author

Larsen, A. C., Guttormsen, M., Schwengner, R., Bleuel, D. L., Goriely, S., Harissopulos, S., Garrote, F. L. Bello, Byun, Y., Eriksen, T. K., Giacoppo, F., Görgen, A., Hagen, T. W., Klintefjord, M., Renstrøm, T., Rose, S. J., Sahin, E., Siem, S., Tornyi, T. G., Tveten, G. M., and Voinov, A. V.

Subjects
*CHEMICAL kinetics, *ENERGY level densities, *NUCLEOSYNTHESIS
Abstract

The nuclear level density and the γ-ray strength function have been extracted for 89Y by using the Oslo method on 89Y(p,p'γ)89Y coincidence data. The γ-ray strength function displays a low-energy enhancement consistent with previous observations in this mass region (93-98Mo). Shell-model calculations support the conclusion that the observed enhancement is due to strong, low-energy M1 transitions at high excitation energies. The data were further used as input for calculations of the 88Sr(p,γ)89Y and 88Y(n,γ)89Y cross sections with the talys reaction code. Comparison with cross-section data, where available, as well as with values from the BRUSLIB library, shows a satisfying agreement. [ABSTRACT FROM AUTHOR]

Published
2016
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229. γ -ray decay from neutron-bound and unbound states in 95Mo and a novel technique for spin determination.

Author

Wiedeking, M., Krtička, M., Bernstein, L. A., Allmond, J. M., Basunia, M. S., Bleuel, D. L., Burke, J. T., Daub, B. H., Fallon, P., Firestone, R. B., Goldblum, B. L., Hatarik, R., Lake, P. T., Larsen, A. C., Lee, I.-Y., Lesher, S. R., Paschalis, S., Petri, M., Phair, L., and Scielzo, N. D.

Subjects
*PHYSICS periodicals, *BOUND states, *NEUTRON emission, *GERMANIUM detectors
Abstract

The emission of γ rays from neutron-bound and neutron-unbound states in 95Mo, populated in the 94Mo(d,p) reaction, has been investigated. Charged particles and γ radiation were detected with arrays of annular silicon and Clover-type high-purity Germanium detectors, respectively. Utilizing p-γ and p-γ-γ coincidences, the 95Mo level scheme was greatly enhanced with 102 new transitions and 43 new states. It agrees well with shell model calculations for excitation energies below ≈2 MeV. From p-γ coincidence data, a new method for the determination of spins of discrete levels is proposed. The method exploits the suppression of high-angular momentum neutron emission from levels with high spins populated in the (d,p) reaction above the neutron separation energy. Spins for almost all 95Mo levels below 2 MeV (and for a few levels above) have been determined with this method. [ABSTRACT FROM AUTHOR]

Published
2016
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230. First Study of the ^{139}Ba(n,γ)^{140}Ba Reaction to Constrain the Conditions for the Astrophysical i Process.

Author

Spyrou A, Mücher D, Denissenkov PA, Herwig F, Good EC, Balk G, Berg HC, Bleuel DL, Clark JA, Dembski C, DeYoung PA, Greaves B, Guttormsen M, Harris C, Larsen AC, Liddick SN, Lyons S, Markova M, Mogannam MJ, Nikas S, Owens-Fryar J, Palmisano-Kyle A, Perdikakis G, Pogliano F, Quintieri M, Richard AL, Santiago-Gonzalez D, Savard G, Smith MK, Sweet A, Tsantiri A, and Wiedeking M

Abstract

New astronomical observations point to a nucleosynthesis picture that goes beyond what was accepted until recently. The intermediate "i" process was proposed as a plausible scenario to explain some of the unusual abundance patterns observed in metal-poor stars. The most important nuclear physics properties entering i-process calculations are the neutron-capture cross sections and they are almost exclusively not known experimentally. Here we provide the first experimental constraints on the ^{139}Ba(n,γ)^{140}Ba reaction rate, which is the dominant source of uncertainty for the production of lanthanum, a key indicator of i-process conditions. This is an important step towards identifying the exact astrophysical site of stars carrying the i-process signature.

Published
2024
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231. Proton Shell Gaps in N=28 Nuclei from the First Complete Spectroscopy Study with FRIB Decay Station Initiator.

Author

Cox I, Xu ZY, Grzywacz R, Ong WJ, Rasco BC, Kitamura N, Hoskins D, Neupane S, Ruland TJ, Allmond JM, King TT, Lubna RS, Rykaczewski KP, Schatz H, Sherrill BM, Tarasov OB, Ayangeakaa AD, Berg HC, Bleuel DL, Cerizza G, Christie J, Chester A, Davis J, Dembski C, Doetsch AA, Duarte JG, Estrade A, Fijałkowska A, Gray TJ, Good EC, Haak K, Hanai S, Harke JT, Harris C, Hermansen K, Hoff DEM, Jain R, Karny M, Kolos K, Laminack A, Liddick SN, Longfellow B, Lyons S, Madurga M, Mogannam MJ, Nowicki A, Ogunbeku TH, Owens-Fryar G, Rajabali MM, Richard AL, Ronning EK, Rose GE, Siegl K, Singh M, Spyrou A, Sweet A, Tsantiri A, Walters WB, and Yokoyama R

Abstract

The first complete measurement of the β-decay strength distribution of &#95;{17}^{45}Cl&#95;{28} was performed at the Facility for Rare Isotope Beams (FRIB) with the FRIB Decay Station Initiator during the second FRIB experiment. The measurement involved the detection of neutrons and γ rays in two focal planes of the FRIB Decay Station Initiator in a single experiment for the first time. This enabled an analytical consistency in extracting the β-decay strength distribution over the large range of excitation energies, including neutron unbound states. We observe a rapid increase in the β-decay strength distribution above the neutron separation energy in &#95;{18}^{45}Ar&#95;{27}. This was interpreted to be caused by the transitioning of neutrons into protons excited across the Z=20 shell gap. The SDPF-MU interaction with reduced shell gap best reproduced the data. The measurement demonstrates a new approach that is sensitive to the proton shell gap in neutron rich nuclei according to SDPF-MU calculations.

Published
2024
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232. Achievement of Target Gain Larger than Unity in an Inertial Fusion Experiment.

Author

Abu-Shawareb H, Acree R, Adams P, Adams J, Addis B, Aden R, Adrian P, Afeyan BB, Aggleton M, Aghaian L, Aguirre A, Aikens D, Akre J, Albert F, Albrecht M, Albright BJ, Albritton J, Alcala J, Alday C, Alessi DA, Alexander N, Alfonso J, Alfonso N, Alger E, Ali SJ, Ali ZA, Allen A, Alley WE, Amala P, Amendt PA, Amick P, Ammula S, Amorin C, Ampleford DJ, Anderson RW, Anklam T, Antipa N, Appelbe B, Aracne-Ruddle C, Araya E, Archuleta TN, Arend M, Arnold P, Arnold T, Arsenlis A, Asay J, Atherton LJ, Atkinson D, Atkinson R, Auerbach JM, Austin B, Auyang L, Awwal AAS, Aybar N, Ayers J, Ayers S, Ayers T, Azevedo S, Bachmann B, Back CA, Bae J, Bailey DS, Bailey J, Baisden T, Baker KL, Baldis H, Barber D, Barberis M, Barker D, Barnes A, Barnes CW, Barrios MA, Barty C, Bass I, Batha SH, Baxamusa SH, Bazan G, Beagle JK, Beale R, Beck BR, Beck JB, Bedzyk M, Beeler RG, Beeler RG, Behrendt W, Belk L, Bell P, Belyaev M, Benage JF, Bennett G, Benedetti LR, Benedict LX, Berger RL, Bernat T, Bernstein LA, Berry B, Bertolini L, Besenbruch G, Betcher J, Bettenhausen R, Betti R, Bezzerides B, Bhandarkar SD, Bickel R, Biener J, Biesiada T, Bigelow K, Bigelow-Granillo J, Bigman V, Bionta RM, Birge NW, Bitter M, Black AC, Bleile R, Bleuel DL, Bliss E, Bliss E, Blue B, Boehly T, Boehm K, Boley CD, Bonanno R, Bond EJ, Bond T, Bonino MJ, Borden M, Bourgade JL, Bousquet J, Bowers J, Bowers M, Boyd R, Boyle D, Bozek A, Bradley DK, Bradley KS, Bradley PA, Bradley L, Brannon L, Brantley PS, Braun D, Braun T, Brienza-Larsen K, Briggs R, Briggs TM, Britten J, Brooks ED, Browning D, Bruhn MW, Brunner TA, Bruns H, Brunton G, Bryant B, Buczek T, Bude J, Buitano L, Burkhart S, Burmark J, Burnham A, Burr R, Busby LE, Butlin B, Cabeltis R, Cable M, Cabot WH, Cagadas B, Caggiano J, Cahayag R, Caldwell SE, Calkins S, Callahan DA, Calleja-Aguirre J, Camara L, Camp D, Campbell EM, Campbell JH, Carey B, Carey R, Carlisle K, Carlson L, Carman L, Carmichael J, Carpenter A, Carr C, Carrera JA, Casavant D, Casey A, Casey DT, Castillo A, Castillo E, Castor JI, Castro C, Caughey W, Cavitt R, Celeste J, Celliers PM, Cerjan C, Chandler G, Chang B, Chang C, Chang J, Chang L, Chapman R, Chapman TD, Chase L, Chen H, Chen H, Chen K, Chen LY, Cheng B, Chittenden J, Choate C, Chou J, Chrien RE, Chrisp M, Christensen K, Christensen M, Christiansen NS, Christopherson AR, Chung M, Church JA, Clark A, Clark DS, Clark K, Clark R, Claus L, Cline B, Cline JA, Cobble JA, Cochrane K, Cohen B, Cohen S, Collette MR, Collins GW, Collins LA, Collins TJB, Conder A, Conrad B, Conyers M, Cook AW, Cook D, Cook R, Cooley JC, Cooper G, Cope T, Copeland SR, Coppari F, Cortez J, Cox J, Crandall DH, Crane J, Craxton RS, Cray M, Crilly A, Crippen JW, Cross D, Cuneo M, Cuotts G, Czajka CE, Czechowicz D, Daly T, Danforth P, Danly C, Darbee R, Darlington B, Datte P, Dauffy L, Davalos G, Davidovits S, Davis P, Davis J, Dawson S, Day RD, Day TH, Dayton M, Deck C, Decker C, Deeney C, DeFriend KA, Deis G, Delamater ND, Delettrez JA, Demaret R, Demos S, Dempsey SM, Desjardin R, Desjardins T, Desjarlais MP, Dewald EL, DeYoreo J, Diaz S, Dimonte G, Dittrich TR, Divol L, Dixit SN, Dixon J, Do A, Dodd ES, Dolan D, Donovan A, Donovan M, Döppner T, Dorrer C, Dorsano N, Douglas MR, Dow D, Downie J, Downing E, Dozieres M, Draggoo V, Drake D, Drake RP, Drake T, Dreifuerst G, Drury O, DuBois DF, DuBois PF, Dunham G, Durocher M, Dylla-Spears R, Dymoke-Bradshaw AKL, Dzenitis B, Ebbers C, Eckart M, Eddinger S, Eder D, Edgell D, Edwards MJ, Efthimion P, Eggert JH, Ehrlich B, Ehrmann P, Elhadj S, Ellerbee C, Elliott NS, Ellison CL, Elsner F, Emerich M, Engelhorn K, England T, English E, Epperson P, Epstein R, Erbert G, Erickson MA, Erskine DJ, Erlandson A, Espinosa RJ, Estes C, Estabrook KG, Evans S, Fabyan A, Fair J, Fallejo R, Farmer N, Farmer WA, Farrell M, Fatherley VE, Fedorov M, Feigenbaum E, Fehrenbach T, Feit M, Felker B, Ferguson W, Fernandez JC, Fernandez-Panella A, Fess S, Field JE, Filip CV, Fincke JR, Finn T, Finnegan SM, Finucane RG, Fischer M, Fisher A, Fisher J, Fishler B, Fittinghoff D, Fitzsimmons P, Flegel M, Flippo KA, Florio J, Folta J, Folta P, Foreman LR, Forrest C, Forsman A, Fooks J, Foord M, Fortner R, Fournier K, Fratanduono DE, Frazier N, Frazier T, Frederick C, Freeman MS, Frenje J, Frey D, Frieders G, Friedrich S, Froula DH, Fry J, Fuller T, Gaffney J, Gales S, Le Galloudec B, Le Galloudec KK, Gambhir A, Gao L, Garbett WJ, Garcia A, Gates C, Gaut E, Gauthier P, Gavin Z, Gaylord J, Geddes CGR, Geissel M, Génin F, Georgeson J, Geppert-Kleinrath H, Geppert-Kleinrath V, Gharibyan N, Gibson J, Gibson C, Giraldez E, Glebov V, Glendinning SG, Glenn S, Glenzer SH, Goade S, Gobby PL, Goldman SR, Golick B, Gomez M, Goncharov V, Goodin D, Grabowski P, Grafil E, Graham P, Grandy J, Grasz E, Graziani FR, Greenman G, Greenough JA, Greenwood A, Gregori G, Green T, Griego JR, Grim GP, Grondalski J, Gross S, Guckian J, Guler N, Gunney B, Guss G, Haan S, Hackbarth J, Hackel L, Hackel R, Haefner C, Hagmann C, Hahn KD, Hahn S, Haid BJ, Haines BM, Hall BM, Hall C, Hall GN, Hamamoto M, Hamel S, Hamilton CE, Hammel BA, Hammer JH, Hampton G, Hamza A, Handler A, Hansen S, Hanson D, Haque R, Harding D, Harding E, Hares JD, Harris DB, Harte JA, Hartouni EP, Hatarik R, Hatchett S, Hauer AA, Havre M, Hawley R, Hayes J, Hayes J, Hayes S, Hayes-Sterbenz A, Haynam CA, Haynes DA, Headley D, Heal A, Heebner JE, Heerey S, Heestand GM, Heeter R, Hein N, Heinbockel C, Hendricks C, Henesian M, Heninger J, Henrikson J, Henry EA, Herbold EB, Hermann MR, Hermes G, Hernandez JE, Hernandez VJ, Herrmann MC, Herrmann HW, Herrera OD, Hewett D, Hibbard R, Hicks DG, Higginson DP, Hill D, Hill K, Hilsabeck T, Hinkel DE, Ho DD, Ho VK, Hoffer JK, Hoffman NM, Hohenberger M, Hohensee M, Hoke W, Holdener D, Holdener F, Holder JP, Holko B, Holunga D, Holzrichter JF, Honig J, Hoover D, Hopkins D, Berzak Hopkins LF, Hoppe M, Hoppe ML, Horner J, Hornung R, Horsfield CJ, Horvath J, Hotaling D, House R, Howell L, Hsing WW, Hu SX, Huang H, Huckins J, Hui H, Humbird KD, Hund J, Hunt J, Hurricane OA, Hutton M, Huynh KH, Inandan L, Iglesias C, Igumenshchev IV, Ivanovich I, Izumi N, Jackson M, Jackson J, Jacobs SD, James G, Jancaitis K, Jarboe J, Jarrott LC, Jasion D, Jaquez J, Jeet J, Jenei AE, Jensen J, Jimenez J, Jimenez R, Jobe D, Johal Z, Johns HM, Johnson D, Johnson MA, Gatu Johnson M, Johnson RJ, Johnson S, Johnson SA, Johnson T, Jones K, Jones O, Jones M, Jorge R, Jorgenson HJ, Julian M, Jun BI, Jungquist R, Kaae J, Kabadi N, Kaczala D, Kalantar D, Kangas K, Karasiev VV, Karasik M, Karpenko V, Kasarky A, Kasper K, Kauffman R, Kaufman MI, Keane C, Keaty L, Kegelmeyer L, Keiter PA, Kellett PA, Kellogg J, Kelly JH, Kemic S, Kemp AJ, Kemp GE, Kerbel GD, Kershaw D, Kerr SM, Kessler TJ, Key MH, Khan SF, Khater H, Kiikka C, Kilkenny J, Kim Y, Kim YJ, Kimko J, Kimmel M, Kindel JM, King J, Kirkwood RK, Klaus L, Klem D, Kline JL, Klingmann J, Kluth G, Knapp P, Knauer J, Knipping J, Knudson M, Kobs D, Koch J, Kohut T, Kong C, Koning JM, Koning P, Konior S, Kornblum H, Kot LB, Kozioziemski B, Kozlowski M, Kozlowski PM, Krammen J, Krasheninnikova NS, Krauland CM, Kraus B, Krauser W, Kress JD, Kritcher AL, Krieger E, Kroll JJ, Kruer WL, Kruse MKG, Kucheyev S, Kumbera M, Kumpan S, Kunimune J, Kur E, Kustowski B, Kwan TJT, Kyrala GA, Laffite S, Lafon M, LaFortune K, Lagin L, Lahmann B, Lairson B, Landen OL, Land T, Lane M, Laney D, Langdon AB, Langenbrunner J, Langer SH, Langro A, Lanier NE, Lanier TE, Larson D, Lasinski BF, Lassle D, LaTray D, Lau G, Lau N, Laumann C, Laurence A, Laurence TA, Lawson J, Le HP, Leach RR, Leal L, Leatherland A, LeChien K, Lechleiter B, Lee A, Lee M, Lee T, Leeper RJ, Lefebvre E, Leidinger JP, LeMire B, Lemke RW, Lemos NC, Le Pape S, Lerche R, Lerner S, Letts S, Levedahl K, Lewis T, Li CK, Li H, Li J, Liao W, Liao ZM, Liedahl D, Liebman J, Lindford G, Lindman EL, Lindl JD, Loey H, London RA, Long F, Loomis EN, Lopez FE, Lopez H, Losbanos E, Loucks S, Lowe-Webb R, Lundgren E, Ludwigsen AP, Luo R, Lusk J, Lyons R, Ma T, Macallop Y, MacDonald MJ, MacGowan BJ, Mack JM, Mackinnon AJ, MacLaren SA, MacPhee AG, Magelssen GR, Magoon J, Malone RM, Malsbury T, Managan R, Mancini R, Manes K, Maney D, Manha D, Mannion OM, Manuel AM, Manuel MJ, Mapoles E, Mara G, Marcotte T, Marin E, Marinak MM, Mariscal DA, Mariscal EF, Marley EV, Marozas JA, Marquez R, Marshall CD, Marshall FJ, Marshall M, Marshall S, Marticorena J, Martinez JI, Martinez D, Maslennikov I, Mason D, Mason RJ, Masse L, Massey W, Masson-Laborde PE, Masters ND, Mathisen D, Mathison E, Matone J, Matthews MJ, Mattoon C, Mattsson TR, Matzen K, Mauche CW, Mauldin M, McAbee T, McBurney M, Mccarville T, McCrory RL, McEvoy AM, McGuffey C, Mcinnis M, McKenty P, McKinley MS, McLeod JB, McPherson A, Mcquillan B, Meamber M, Meaney KD, Meezan NB, Meissner R, Mehlhorn TA, Mehta NC, Menapace J, Merrill FE, Merritt BT, Merritt EC, Meyerhofer DD, Mezyk S, Mich RJ, Michel PA, Milam D, Miller C, Miller D, Miller DS, Miller E, Miller EK, Miller J, Miller M, Miller PE, Miller T, Miller W, Miller-Kamm V, Millot M, Milovich JL, Minner P, Miquel JL, Mitchell S, Molvig K, Montesanti RC, Montgomery DS, Monticelli M, Montoya A, Moody JD, Moore AS, Moore E, Moran M, Moreno JC, Moreno K, Morgan BE, Morrow T, Morton JW, Moses E, Moy K, Muir R, Murillo MS, Murray JE, Murray JR, Munro DH, Murphy TJ, Munteanu FM, Nafziger J, Nagayama T, Nagel SR, Nast R, Negres RA, Nelson A, Nelson D, Nelson J, Nelson S, Nemethy S, Neumayer P, Newman K, Newton M, Nguyen H, Di Nicola JG, Di Nicola P, Niemann C, Nikroo A, Nilson PM, Nobile A, Noorai V, Nora RC, Norton M, Nostrand M, Note V, Novell S, Nowak PF, Nunez A, Nyholm RA, O'Brien M, Oceguera A, Oertel JA, Oesterle AL, Okui J, Olejniczak B, Oliveira J, Olsen P, Olson B, Olson K, Olson RE, Opachich YP, Orsi N, Orth CD, Owen M, Padalino S, Padilla E, Paguio R, Paguio S, Paisner J, Pajoom S, Pak A, Palaniyappan S, Palma K, Pannell T, Papp F, Paras D, Parham T, Park HS, Pasternak A, Patankar S, Patel MV, Patel PK, Patterson R, Patterson S, Paul B, Paul M, Pauli E, Pearce OT, Pearcy J, Pedretti A, Pedrotti B, Peer A, Pelz LJ, Penetrante B, Penner J, Perez A, Perkins LJ, Pernice E, Perry TS, Person S, Petersen D, Petersen T, Peterson DL, Peterson EB, Peterson JE, Peterson JL, Peterson K, Peterson RR, Petrasso RD, Philippe F, Phillion D, Phipps TJ, Piceno E, Pickworth L, Ping Y, Pino J, Piston K, Plummer R, Pollack GD, Pollaine SM, Pollock BB, Ponce D, Ponce J, Pontelandolfo J, Porter JL, Post J, Poujade O, Powell C, Powell H, Power G, Pozulp M, Prantil M, Prasad M, Pratuch S, Price S, Primdahl K, Prisbrey S, Procassini R, Pruyne A, Pudliner B, Qiu SR, Quan K, Quinn M, Quintenz J, Radha PB, Rainer F, Ralph JE, Raman KS, Raman R, Rambo PW, Rana S, Randewich A, Rardin D, Ratledge M, Ravelo N, Ravizza F, Rayce M, Raymond A, Raymond B, Reed B, Reed C, Regan S, Reichelt B, Reis V, Reisdorf S, Rekow V, Remington BA, Rendon A, Requieron W, Rever M, Reynolds H, Reynolds J, Rhodes J, Rhodes M, Richardson MC, Rice B, Rice NG, Rieben R, Rigatti A, Riggs S, Rinderknecht HG, Ring K, Riordan B, Riquier R, Rivers C, Roberts D, Roberts V, Robertson G, Robey HF, Robles J, Rocha P, Rochau G, Rodriguez J, Rodriguez S, Rosen MD, Rosenberg M, Ross G, Ross JS, Ross P, Rouse J, Rovang D, Rubenchik AM, Rubery MS, Ruiz CL, Rushford M, Russ B, Rygg JR, Ryujin BS, Sacks RA, Sacks RF, Saito K, Salmon T, Salmonson JD, Sanchez J, Samuelson S, Sanchez M, Sangster C, Saroyan A, Sater J, Satsangi A, Sauers S, Saunders R, Sauppe JP, Sawicki R, Sayre D, Scanlan M, Schaffers K, Schappert GT, Schiaffino S, Schlossberg DJ, Schmidt DW, Schmit PF, Smidt JM, Schneider DHG, Schneider MB, Schneider R, Schoff M, Schollmeier M, Schroeder CR, Schrauth SE, Scott HA, Scott I, Scott JM, Scott RHH, Scullard CR, Sedillo T, Seguin FH, Seka W, Senecal J, Sepke SM, Seppala L, Sequoia K, Severyn J, Sevier JM, Sewell N, Seznec S, Shah RC, Shamlian J, Shaughnessy D, Shaw M, Shaw R, Shearer C, Shelton R, Shen N, Sherlock MW, Shestakov AI, Shi EL, Shin SJ, Shingleton N, Shmayda W, Shor M, Shoup M, Shuldberg C, Siegel L, Silva FJ, Simakov AN, Sims BT, Sinars D, Singh P, Sio H, Skulina K, Skupsky S, Slutz S, Sluyter M, Smalyuk VA, Smauley D, Smeltser RM, Smith C, Smith I, Smith J, Smith L, Smith R, Smith R, Schölmerich M, Sohn R, Sommer S, Sorce C, Sorem M, Soures JM, Spaeth ML, Spears BK, Speas S, Speck D, Speck R, Spears J, Spinka T, Springer PT, Stadermann M, Stahl B, Stahoviak J, Stanley J, Stanton LG, Steele R, Steele W, Steinman D, Stemke R, Stephens R, Sterbenz S, Sterne P, Stevens D, Stevers J, Still CH, Stoeckl C, Stoeffl W, Stolken JS, Stolz C, Storm E, Stone G, Stoupin S, Stout E, Stowers I, Strauser R, Streckart H, Streit J, Strozzi DJ, Stutz J, Summers L, Suratwala T, Sutcliffe G, Suter LJ, Sutton SB, Svidzinski V, Swadling G, Sweet W, Szoke A, Tabak M, Takagi M, Tambazidis A, Tang V, Taranowski M, Taylor LA, Telford S, 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Wilcox R, Wilcox S, Wild C, Wilde BH, Wilde CH, Wilhelmsen K, Wilke MD, Wilkens H, Wilkins P, Wilks SC, Williams EA, Williams GJ, Williams W, Williams WH, Wilson DC, Wilson B, Wilson E, Wilson R, Winters S, Wisoff PJ, Wittman M, Wolfe J, Wong A, Wong KW, Wong L, Wong N, Wood R, Woodhouse D, Woodruff J, Woods DT, Woods S, Woodworth BN, Wooten E, Wootton A, Work K, Workman JB, Wright J, Wu M, Wuest C, Wysocki FJ, Xu H, Yamaguchi M, Yang B, Yang ST, Yatabe J, Yeamans CB, Yee BC, Yi SA, Yin L, Young B, Young CS, Young CV, Young P, Youngblood K, Yu J, Zacharias R, Zagaris G, Zaitseva N, Zaka F, Ze F, Zeiger B, Zika M, Zimmerman GB, Zobrist T, Zuegel JD, and Zylstra AB

Abstract

On December 5, 2022, an indirect drive fusion implosion on the National Ignition Facility (NIF) achieved a target gain G&#95;{target} of 1.5. This is the first laboratory demonstration of exceeding "scientific breakeven" (or G&#95;{target}>1) where 2.05 MJ of 351 nm laser light produced 3.1 MJ of total fusion yield, a result which significantly exceeds the Lawson criterion for fusion ignition as reported in a previous NIF implosion [H. Abu-Shawareb et al. (Indirect Drive ICF Collaboration), Phys. Rev. Lett. 129, 075001 (2022)PRLTAO0031-900710.1103/PhysRevLett.129.075001]. This achievement is the culmination of more than five decades of research and gives proof that laboratory fusion, based on fundamental physics principles, is possible. This Letter reports on the target, laser, design, and experimental advancements that led to this result.

Published
2024
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233. Statistical (n, γ ) cross section model comparison for short-lived nuclei.

Author

Lewis R, Couture A, Liddick SN, Spyrou A, Bleuel DL, Campo LC, Crider BP, Dombos AC, Guttormsen M, Kawano T, Larsen AC, Lewis AM, Mosby S, Perdikakis G, Prokop CJ, Quinn SJ, Renstrøm T, and Siem S

Abstract

Neutron-capture cross sections of neutron-rich nuclei are calculated using a Hauser-Feshbach model when direct experimental cross sections cannot be obtained. A number of codes to perform these calculations exist, and each makes different assumptions about the underlying nuclear physics. We investigated the systematic uncertainty associated with the choice of Hauser-Feshbach code used to calculate the neutron-capture cross section of a short-lived nucleus. The neutron-capture cross section for 73 Zn (n, γ ) 74 Zn was calculated using three Hauser-Feshbach statistical model codes: TALYS, CoH, and EMPIRE. The calculation was first performed without any changes to the default settings in each code. Then an experimentally obtained nuclear level density (NLD) and γ -ray strength function ( γ SF ) were included. Finally, the nuclear structure information was made consistent across the codes. The neutron-capture cross sections obtained from the three codes are in good agreement after including the experimentally obtained NLD and γ SF , accounting for differences in the underlying nuclear reaction models, and enforcing consistent approximations for unknown nuclear data. It is possible to use consistent inputs and nuclear physics to reduce the differences in the calculated neutron-capture cross section from different Hauser-Feshbach codes. However, ensuring the treatment of the input of experimental data and other nuclear physics are similar across multiple codes requires a careful investigation. For this reason, more complete documentation of the inputs and physics chosen is important., Supplementary Information: The online version contains supplementary material available at 10.1140/epja/s10050-023-00920-0., (© The Author(s) 2023.)

Published
2023
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234. The 40 Ar(d,p) 41 Ar cross section between 3-7 MeV.

Author

Bleuel DL, Anderson SG, Bernstein LA, Brown JA, Caggiano JA, Goldblum BL, Gordon JM, Hall JM, Harrig KP, Johnson MS, Laplace TA, Marsh RA, Montague ME, Ratkiewicz A, Rusnak B, and Velsko CA

Subjects
Cyclotrons
Abstract

To determine the safety of using argon as a deuteron beam stopping material, the   40 Ar(d,p) 41 Ar cross section was measured at average deuteron energies of 3.6 MeV, 5.5 MeV, and 7.0 MeV using an activation method. A 16-MeV deuteron beam produced by Lawrence Berkeley National Laboratory's 88-Inch Cyclotron was degraded to each energy by nickel foils and the front wall of an aluminum gas chamber. The reduced-energy deuterons were used to activate a sample of nat Ar gas. After each irradiation, the gas chamber's   41 Ar activation was measured with a high-purity germanium detector. The cross sections measured were larger than a previous measurement by ∼40%., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Published
2022
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235. Lawson Criterion for Ignition Exceeded in an Inertial Fusion Experiment.

Author

Abu-Shawareb H, Acree R, Adams P, Adams J, Addis B, Aden R, Adrian P, Afeyan BB, Aggleton M, Aghaian L, Aguirre A, Aikens D, Akre J, Albert F, Albrecht M, Albright BJ, Albritton J, Alcala J, Alday C, Alessi DA, Alexander N, Alfonso J, Alfonso N, Alger E, Ali SJ, Ali ZA, Alley WE, Amala P, Amendt PA, Amick P, Ammula S, Amorin C, Ampleford DJ, Anderson RW, Anklam T, Antipa N, Appelbe B, Aracne-Ruddle C, Araya E, Arend M, Arnold P, Arnold T, Asay J, Atherton LJ, Atkinson D, Atkinson R, Auerbach JM, Austin B, Auyang L, Awwal AS, Ayers J, Ayers S, Ayers T, Azevedo S, Bachmann B, Back CA, Bae J, Bailey DS, Bailey J, Baisden T, Baker KL, Baldis H, Barber D, Barberis M, Barker D, Barnes A, Barnes CW, Barrios MA, Barty C, Bass I, Batha SH, Baxamusa SH, Bazan G, Beagle JK, Beale R, Beck BR, Beck JB, Bedzyk M, Beeler RG, Beeler RG, Behrendt W, Belk L, Bell P, Belyaev M, Benage JF, Bennett G, Benedetti LR, Benedict LX, Berger R, Bernat T, Bernstein LA, Berry B, Bertolini L, Besenbruch G, Betcher J, Bettenhausen R, Betti R, Bezzerides B, Bhandarkar SD, Bickel R, Biener J, Biesiada T, Bigelow K, Bigelow-Granillo J, Bigman V, Bionta RM, Birge NW, Bitter M, Black AC, Bleile R, Bleuel DL, Bliss E, Bliss E, Blue B, Boehly T, Boehm K, Boley CD, Bonanno R, Bond EJ, Bond T, Bonino MJ, Borden M, Bourgade JL, Bousquet J, Bowers J, Bowers M, Boyd R, Bozek A, Bradley DK, Bradley KS, Bradley PA, Bradley L, Brannon L, Brantley PS, Braun D, Braun T, Brienza-Larsen K, Briggs TM, Britten J, Brooks ED, Browning D, Bruhn MW, Brunner TA, Bruns H, Brunton G, Bryant B, Buczek T, Bude J, Buitano L, Burkhart S, Burmark J, Burnham A, Burr R, Busby LE, Butlin B, Cabeltis R, Cable M, Cabot WH, Cagadas B, Caggiano J, Cahayag R, Caldwell SE, Calkins S, Callahan DA, Calleja-Aguirre J, Camara L, Camp D, Campbell EM, Campbell JH, Carey B, Carey R, Carlisle K, Carlson L, Carman L, Carmichael J, Carpenter A, Carr C, Carrera JA, Casavant D, Casey A, Casey DT, Castillo A, Castillo E, Castor JI, Castro C, Caughey W, Cavitt R, Celeste J, Celliers PM, Cerjan C, Chandler G, Chang B, Chang C, Chang J, Chang L, Chapman R, Chapman T, Chase L, Chen H, Chen H, Chen K, Chen LY, Cheng B, Chittenden J, Choate C, Chou J, Chrien RE, Chrisp M, Christensen K, Christensen M, Christopherson AR, Chung M, Church JA, Clark A, Clark DS, Clark K, Clark R, Claus L, Cline B, Cline JA, Cobble JA, Cochrane K, Cohen B, Cohen S, Collette MR, Collins G, Collins LA, Collins TJB, Conder A, Conrad B, Conyers M, Cook AW, Cook D, Cook R, Cooley JC, Cooper G, Cope T, Copeland SR, Coppari F, Cortez J, Cox J, Crandall DH, Crane J, Craxton RS, Cray M, Crilly A, Crippen JW, Cross D, Cuneo M, Cuotts G, Czajka CE, Czechowicz D, Daly T, Danforth P, Darbee R, Darlington B, Datte P, Dauffy L, Davalos G, Davidovits S, Davis P, Davis J, Dawson S, Day RD, Day TH, Dayton M, Deck C, Decker C, Deeney C, DeFriend KA, Deis G, Delamater ND, Delettrez JA, Demaret R, Demos S, Dempsey SM, Desjardin R, Desjardins T, Desjarlais MP, Dewald EL, DeYoreo 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Person S, Petersen D, Petersen T, Peterson DL, Peterson EB, Peterson JE, Peterson JL, Peterson K, Peterson RR, Petrasso RD, Philippe F, Phipps TJ, Piceno E, Ping Y, Pickworth L, Pino J, Plummer R, Pollack GD, Pollaine SM, Pollock BB, Ponce D, Ponce J, Pontelandolfo J, Porter JL, Post J, Poujade O, Powell C, Powell H, Power G, Pozulp M, Prantil M, Prasad M, Pratuch S, Price S, Primdahl K, Prisbrey S, Procassini R, Pruyne A, Pudliner B, Qiu SR, Quan K, Quinn M, Quintenz J, Radha PB, Rainer F, Ralph JE, Raman KS, Raman R, Rambo P, Rana S, Randewich A, Rardin D, Ratledge M, Ravelo N, Ravizza F, Rayce M, Raymond A, Raymond B, Reed B, Reed C, Regan S, Reichelt B, Reis V, Reisdorf S, Rekow V, Remington BA, Rendon A, Requieron W, Rever M, Reynolds H, Reynolds J, Rhodes J, Rhodes M, Richardson MC, Rice B, Rice NG, Rieben R, Rigatti A, Riggs S, Rinderknecht HG, Ring K, Riordan B, Riquier R, Rivers C, Roberts D, Roberts V, Robertson G, Robey HF, Robles J, Rocha P, Rochau G, Rodriguez J, Rodriguez S, Rosen M, Rosenberg M, Ross G, Ross JS, Ross P, Rouse J, Rovang D, Rubenchik AM, Rubery MS, Ruiz CL, Rushford M, Russ B, Rygg JR, Ryujin BS, Sacks RA, Sacks RF, Saito K, Salmon T, Salmonson JD, Sanchez J, Samuelson S, Sanchez M, Sangster C, Saroyan A, Sater J, Satsangi A, Sauers S, Saunders R, Sauppe JP, Sawicki R, Sayre D, Scanlan M, Schaffers K, Schappert GT, Schiaffino S, Schlossberg DJ, Schmidt DW, Schmitt MJ, Schneider DHG, Schneider MB, Schneider R, Schoff M, Schollmeier M, Schölmerich M, Schroeder CR, Schrauth SE, Scott HA, Scott I, Scott JM, Scott RHH, Scullard CR, Sedillo T, Seguin FH, Seka W, Senecal J, Sepke SM, Seppala L, Sequoia K, Severyn J, Sevier JM, Sewell N, Seznec S, Shah RC, Shamlian J, Shaughnessy D, Shaw M, Shaw R, Shearer C, Shelton R, Shen N, Sherlock MW, Shestakov AI, Shi EL, Shin SJ, Shingleton N, Shmayda W, Shor M, Shoup M, Shuldberg C, Siegel L, Silva FJ, Simakov AN, Sims BT, Sinars D, Singh P, Sio H, Skulina K, Skupsky S, Slutz S, Sluyter M, Smalyuk VA, Smauley D, Smeltser RM, Smith C, Smith I, Smith J, Smith L, Smith R, Sohn R, Sommer S, Sorce C, Sorem M, Soures JM, Spaeth ML, Spears BK, Speas S, Speck D, Speck R, Spears J, Spinka T, Springer PT, Stadermann M, Stahl B, Stahoviak J, Stanton LG, Steele R, Steele W, Steinman D, Stemke R, Stephens R, Sterbenz S, Sterne P, Stevens D, Stevers J, Still CB, Stoeckl C, Stoeffl W, Stolken JS, Stolz C, Storm E, Stone G, Stoupin S, Stout E, Stowers I, Strauser R, Streckart H, Streit J, Strozzi DJ, Suratwala T, Sutcliffe G, Suter LJ, Sutton SB, Svidzinski V, Swadling G, Sweet W, Szoke A, Tabak M, Takagi M, Tambazidis A, Tang V, Taranowski M, Taylor LA, Telford S, Theobald W, Thi M, Thomas A, Thomas CA, Thomas I, Thomas R, Thompson IJ, Thongstisubskul A, Thorsness CB, Tietbohl G, Tipton RE, Tobin M, Tomlin N, Tommasini R, Toreja AJ, Torres J, Town RPJ, Townsend S, Trenholme J, Trivelpiece A, Trosseille C, Truax H, Trummer D, Trummer S, Truong T, Tubbs D, Tubman ER, Tunnell T, Turnbull D, Turner RE, Ulitsky M, Upadhye R, Vaher JL, VanArsdall P, VanBlarcom D, Vandenboomgaerde M, VanQuinlan R, Van Wonterghem BM, Varnum WS, Velikovich AL, Vella A, Verdon CP, Vermillion B, Vernon S, Vesey R, Vickers J, Vignes RM, Visosky M, Vocke J, Volegov PL, Vonhof S, Von Rotz R, Vu HX, Vu M, Wall D, Wall J, Wallace R, Wallin B, Walmer D, Walsh CA, Walters CF, Waltz C, Wan A, Wang A, Wang Y, Wark JS, Warner BE, Watson J, Watt RG, Watts P, Weaver J, Weaver RP, Weaver S, Weber CR, Weber P, Weber SV, Wegner P, Welday B, Welser-Sherrill L, Weiss K, Widmann K, Wheeler GF, Whistler W, White RK, Whitley HD, Whitman P, Wickett ME, Widmayer C, Wiedwald J, Wilcox R, Wilcox S, Wild C, Wilde BH, Wilde CH, Wilhelmsen K, Wilke MD, Wilkens H, Wilkins P, Wilks SC, Williams EA, Williams GJ, Williams W, Williams WH, Wilson DC, Wilson B, Wilson E, Wilson R, Winters S, Wisoff J, Wittman M, Wolfe J, Wong A, Wong KW, Wong L, Wong N, Wood R, Woodhouse D, Woodruff J, Woods DT, Woods S, Woodworth BN, Wooten E, Wootton A, Work K, Workman JB, Wright J, Wu M, Wuest C, Wysocki FJ, Xu H, Yamaguchi M, Yang B, Yang ST, Yatabe J, Yeamans CB, Yee BC, Yi SA, Yin L, Young B, Young CS, Young CV, Young P, Youngblood K, Zacharias R, Zagaris G, Zaitseva N, Zaka F, Ze F, Zeiger B, Zika M, Zimmerman GB, Zobrist T, Zuegel JD, and Zylstra AB

Abstract

For more than half a century, researchers around the world have been engaged in attempts to achieve fusion ignition as a proof of principle of various fusion concepts. Following the Lawson criterion, an ignited plasma is one where the fusion heating power is high enough to overcome all the physical processes that cool the fusion plasma, creating a positive thermodynamic feedback loop with rapidly increasing temperature. In inertially confined fusion, ignition is a state where the fusion plasma can begin "burn propagation" into surrounding cold fuel, enabling the possibility of high energy gain. While "scientific breakeven" (i.e., unity target gain) has not yet been achieved (here target gain is 0.72, 1.37 MJ of fusion for 1.92 MJ of laser energy), this Letter reports the first controlled fusion experiment, using laser indirect drive, on the National Ignition Facility to produce capsule gain (here 5.8) and reach ignition by nine different formulations of the Lawson criterion.

Published
2022
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236. Precision measurement of relative γ-ray intensities from the decay of 61 Cu.

Author

Bleuel DL, Bernstein LA, Marsh RA, Morrell JT, Rusnak B, and Voyles AS

Abstract

A discrepancy, well outside reported uncertainties, has been observed between the accepted and measured values of the intensity ratio of the two strongest γ rays following 61 Cu β + decay. This discrepancy has significant impact since the nat Ni(d,x) 61 Cu reaction has historically been one of only a few IAEA recommendations for use as a deuteron flux monitor and a considerable number of published cross sections measured in ratio to that beam monitor cross section may depend on the choice of either the first or second strongest γ ray in those calculations. To determine the magnitude of this error most precisely, over a hundred separate measurements of the 283 keV to 656 keV γ-ray emission ratio were collected from seven experiments and a variety of detectors and detection geometries. A weighted average of all these measurements indicates an error in the value listed in the Nuclear Data Sheets of 11% in either the primary or second-highest intensity γ ray of 61 Cu, potentially introducing an 11% error in 61 Cu production cross section measurements, cross sections using nickel activation as a deuteron beam current monitor, or in dose rates when 61 Cu is used in nuclear medicine. General agreement with the Data Sheets with ten other intensity ratios suggests the most probable error is in the secondary (656 keV) emission, which accordingly should be updated from 10.8% to 9.69%., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Published
2021
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238. Anomalies in the Charge Yields of Fission Fragments from the ^{238}U(n,f) Reaction.

Author

Wilson JN, Lebois M, Qi L, Amador-Celdran P, Bleuel D, Briz JA, Carroll R, Catford W, De Witte H, Doherty DT, Eloirdi R, Georgiev G, Gottardo A, Goasduff A, Hadyńska-Klęk K, Hauschild K, Hess H, Ingeberg V, Konstantinopoulos T, Ljungvall J, Lopez-Martens A, Lorusso G, Lozeva R, Lutter R, Marini P, Matea I, Materna T, Mathieu L, Oberstedt A, Oberstedt S, Panebianco S, Podolyák Z, Porta A, Regan PH, Reiter P, Rezynkina K, Rose SJ, Sahin E, Seidlitz M, Serot O, Shearman R, Siebeck B, Siem S, Smith AG, Tveten GM, Verney D, Warr N, Zeiser F, and Zielinska M

Abstract

Fast-neutron-induced fission of ^{238}U at an energy just above the fission threshold is studied with a novel technique which involves the coupling of a high-efficiency γ-ray spectrometer (MINIBALL) to an inverse-kinematics neutron source (LICORNE) to extract charge yields of fission fragments via γ-γ coincidence spectroscopy. Experimental data and fission models are compared and found to be in reasonable agreement for many nuclei; however, significant discrepancies of up to 600% are observed, particularly for isotopes of Sn and Mo. This indicates that these models significantly overestimate the standard 1 fission mode and suggests that spherical shell effects in the nascent fission fragments are less important for low-energy fast-neutron-induced fission than for thermal neutron-induced fission. This has consequences for understanding and modeling the fission process, for experimental nuclear structure studies of the most neutron-rich nuclei, for future energy applications (e.g., Generation IV reactors which use fast-neutron spectra), and for the reactor antineutrino anomaly.

Published
2017
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239. Lifetime measurement of the first excited 2+ state in 16C.

Author

Wiedeking M, Fallon P, Macchiavelli AO, Gibelin J, Basunia MS, Clark RM, Cromaz M, Deleplanque MA, Gros S, Jeppesen HB, Lake PT, Lee IY, Moretto LG, Pavan J, Phair L, Rodriguez-Vietiez E, Bernstein LA, Bleuel DL, Burke JT, Lesher SR, Lyles BF, and Scielzo ND

Abstract

The lifetime of the 2&#95;+(1) state in 16C has been measured with the recoil distance method using the 9Be(9Be,2p) fusion-evaporation reaction at a beam energy of 40 MeV. The mean lifetime was measured to be 11.7(20) ps corresponding to a B(E2;2&#95;+(1)-->0+) value of 4.15(73)e&#95;2 fm&#95;4 [1.73(30) W.u.], consistent with other even-even closed shell nuclei. Our result does not support an interpretation for "decoupled" valence neutrons.

Published
2008
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240. BNCT dose distribution in liver with epithermal D-D and D-T fusion-based neutron beams.

Author

Koivunoro H, Bleuel DL, Nastasi U, Lou TP, Reijonen J, and Leung KN

Subjects
Boron Neutron Capture Therapy instrumentation, Boron Neutron Capture Therapy methods, Computer Simulation, Fast Neutrons therapeutic use, Humans, Liver Neoplasms diagnostic imaging, Phantoms, Imaging, Radiotherapy Dosage, Radiotherapy Planning, Computer-Assisted, Relative Biological Effectiveness, Tomography, X-Ray Computed, Boron Neutron Capture Therapy statistics & numerical data, Liver Neoplasms radiotherapy
Abstract

Recently, a new application of boron neutron capture therapy (BNCT) treatment has been introduced. Results have indicated that liver tumors can be treated by BNCT after removal of the liver from the body. At Lawrence Berkeley National Laboratory, compact neutron generators based on (2)H(d,n)(3)He (D-D) or (3)H(t,n)(4)He (D-T) fusion reactions are being developed. Preliminary simulations of the applicability of 2.45 MeV D-D fusion and 14.1 MeV D-T fusion neutrons for in vivo liver tumor BNCT, without removing the liver from the body, have been carried out. MCNP simulations were performed in order to find a moderator configuration for creating a neutron beam of optimal neutron energy and to create a source model for dose calculations with the simulation environment for radiotherapy applications (SERA) treatment planning program. SERA dose calculations were performed in a patient model based on CT scans of the body. The BNCT dose distribution in liver and surrounding healthy organs was calculated with rectangular beam aperture sizes of 20 cm x 20 cm and 25 cm x 25 cm. Collimator thicknesses of 10 and 15 cm were used. The beam strength to obtain a practical treatment time was studied. In this paper, the beam shaping assemblies for D-D and D-T neutron generators and dose calculation results are presented.

Published
2004
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241. Boron neutron capture therapy (BNCT): implications of neutron beam and boron compound characteristics.

Author

Wheeler FJ, Nigg DW, Capala J, Watkins PR, Vroegindeweij C, Auterinen I, Seppälä T, and Bleuel D

Subjects
Biophysics methods, Boron Compounds chemistry, Brain anatomy & histology, Fructose chemistry, Fructose therapeutic use, Gamma Rays, Head, Humans, Monte Carlo Method, Neutrons therapeutic use, Nuclear Reactors, Particle Accelerators, Probability, Radiation-Sensitizing Agents chemistry, Radiotherapy Dosage, Boron Compounds therapeutic use, Boron Neutron Capture Therapy methods, Brain Neoplasms radiotherapy, Fructose analogs & derivatives, Glioma radiotherapy, Radiation-Sensitizing Agents therapeutic use
Abstract

The potential efficacy of boron neutron capture therapy (BNCT) for malignant glioma is a significant function of epithermal-neutron beam biophysical characteristics as well as boron compound biodistribution characteristics. Monte Carlo analyses were performed to evaluate the relative significance of these factors on theoretical tumor control using a standard model. The existing, well-characterized epithermal-neutron sources at the Brookhaven Medical Research Reactor (BMRR), the Petten High Flux Reactor (HFR), and the Finnish Research Reactor (FiR-1) were compared. Results for a realistic accelerator design by the E. O. Lawrence Berkeley National Laboratory (LBL) are also compared. Also the characteristics of the compound p-Boronophenylaline Fructose (BPA-F) and a hypothetical next-generation compound were used in a comparison of the BMRR and a hypothetical improved reactor. All components of dose induced by an external epithermal-neutron beam fall off quite rapidly with depth in tissue. Delivery of dose to greater depths is limited by the healthy-tissue tolerance and a reduction in the hydrogen-recoil and incident gamma dose allow for longer irradiation and greater dose at a depth. Dose at depth can also be increased with a beam that has higher neutron energy (without too high a recoil dose) and a more forward peaked angular distribution. Of the existing facilities, the FiR-1 beam has the better quality (lower hydrogen-recoil and incident gamma dose) and a penetrating neutron spectrum and was found to deliver a higher value of Tumor Control Probability (TCP) than other existing beams at shallow depth. The greater forwardness and penetration of the HFR the FiR-1 at greater depths. The hypothetical reactor and accelerator beams outperform at both shallow and greater depths. In all cases, the hypothetical compound provides a significant improvement in efficacy but it is shown that the full benefit of improved compound is not realized until the neutron beam is fully optimized.

Published
1999
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