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166 results on '"Peters E. E."'

1. Relevance of the Nuclear Structure of the Stable Ge Isotopes to the Neutrino-less Double-Beta Decay of 76Ge

Author

Yates S. W., Peters E. E., Crider B. P., Mukhopadhyay S., and Ramirez A. P. D.

Subjects
Physics, QC1-999
Abstract

Gamma-ray detection following the inelastic neutron scattering reaction on isotopically enriched material was used to study the nuclear structure of 74Ge. From these measurements, low-lying, low-spin excited states were characterized, new states and their decays were identified, level lifetimes were measured with the Doppler-shift attenuation method (DSAM), multipole mixing ratios were established, and transition probabilities were determined. New structural features in 74Ge were identified, and the reanalysis of older 76Ge data led to the placement of the 2+ member of the intruder band. In addition, a number of previously placed states in 74Ge were shown not to exist. A procedure for future work, which will lead to meaningful data for constraining calculations of the neutrinoless double-beta decay matrix element, is suggested.

Published
2020
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3. Studies of 54,56Fe Neutron Scattering Cross Sections

Author

Hicks S. F., Vanhoy J. R., French A. J., Henderson S. L., Howard T. J., Pecha R. L., Santonil Z. C., Crider B. P., Liu S., McEllistrem M. T., Peters E. E., Prados-Estévez F.M., Ross T. J., and Yates S.W.

Subjects
Physics, QC1-999
Abstract

Elastic and inelastic neutron scattering differential cross sections and γ-ray production cross sections have been measured on 54,56Fe at several incident energies in the fast neutron region between 1.5 and 4.7 MeV. All measurements were completed at the University of Kentucky Accelerator Laboratory (UKAL) using a 7-MV Model CN Van de Graaff accelerator, along with the neutron production and neutron and γ-ray detection systems located there. The facilities at UKAL allow the investigation of both elastic and inelastic scattering with nearly mono-energetic incident neutrons. Time-of-flight techniques were used to detect the scattered neutrons for the differential cross section measurements. The measured cross sections are important for fission reactor applications and also for testing global model calculations such as those found at ENDF, since describing both the elastic and inelastic scattering is important for determining the direct and compound components of the scattering mechanism. The γ-ray production cross sections are used to determine cross sections to unresolved levels in the neutron scattering experiments. Results from our measurements and comparisons to model calculations are presented.

Published
2015
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4. Inelastic neutron scattering studies of 76Ge and 76Se: relevance to elevance to neutrinoless double-β decay

Author

Crider B. P., Peters E. E., Ross T. J., McEllistrem M. T., Prados-Estévez F. M., Allmond J. M., Vanhoy J. R., and Yates S. W.

Subjects
Physics, QC1-999
Abstract

Inelastic neutron scattering measurements were performed at the University of Kentucky Accelerator Laboratory on enriched 76Ge and 76Se scattering samples. From measurements at incident neutron energies from 2.0 to 4.0 MeV, many new levels were identified and characterized in each nucleus; level lifetimes, transition probabilities, multipole mixing ratios, and other properties were determined. In addition, γ-ray cross sections for the 76Ge(n,n′γ) reaction were measured at neutron energies up to 5.0 MeV, with the goal of determining the cross sections of γ rays in 2040-keV region, which corresponds to the region of interest in the neutrinoless double β decay of 76Ge. Gamma rays from the three strongest branches from the 3952-keV level were observed, but the previously reported 2041-keV γ ray was not. Population cross sections across the range of incident neutron energies were determined for the 3952-keV level, resulting in a cross section of ~0.1 mb for the 2041-keV branch using the previously determined branching ratios. Beyond this, the data from these experiments indicate that previously unreported γ rays from levels in 76Ge can be found in the 2039-keV region.

Published
2015
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5. Level Lifetimes in 94Zr from DSAM Measurements following Inelastic Neutron Scattering

Author

Yates S. W., Peters E. E., Chakraborty A., Crider B. P., McEllistrem M. T., Prados-Estévez F. M., and Vanhoy J. R.

Subjects
Physics, QC1-999
Abstract

The lifetime of the second 2+ state in 94Zr was redetermined by the Doppler-shift attenuation method following inelastic neutron scattering (DSAM-INS) from metallic Zr and ZrO2 samples of natural isotopic abundance. The new value for the level lifetime differs significantly from the previously published value, with the new lifetime found to be roughly twice that value. A reanalysis of the original γ-ray data from the enriched 94ZrO2 sample failed to expose the source of this discrepancy; however, powder X-ray diffraction and scanning electron microscopy performed on each scattering sample, including the enriched sample used previously, provide clues to an explanation and reveal the role of the chemical properties of the sample material in DSAM-INS lifetime determinations.

Published
2014
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6. Inelastic Neutron Scattering on 160Gd

Author

Lesher S. R., Casarella C., Crider B. P., Ikeyama R., Marsh I., Peters E. E., Prados-Estévez F. M., Smith M. K., Tully Z., Vanhoy J. R., Aprahamian A., and Yates S. W.

Subjects
Physics, QC1-999
Abstract

The nature of low-lying excitations, Kπ=0+ bands in deformed nuclei remain enigmatic in the field, especially in relationship to quadrupole vibrations. One method of characterizing these states beyond excitation energies is through measurements of absolute transition probabilities. In the rare earth region of deformation, there are five stable Gd isotopes, 154Gd, 156Gd, and 158Gd have been studied to obtain B(E2) values, a fourth, 160Gd is the focus of this work. We have examined 160Gd with the (n, n′γ) reaction and neutron energies up to 3.0 MeV to confirm known 0+ states.

Published
2014
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7. Spectroscopic study of $^{47}$Ca from the $\beta^-$ decay of $^{47}$K

Author

Smith, J. K., Garnsworthy, A. B., Pore, J. L., Andreoiu, C., MacLean, A. D., Chester, A., Beadle, Z., Ball, G. C., Bender, P. C., Bildstein, V., Braid, R., Varela, A. Diaz, Dunlop, R., Evitts, L. J., Garrett, P. E., Hackman, G., Ilyushkin, S. V., Jigmeddorj, B., Kuhn, K., Laffoley, A. T., Leach, K. G., Miller, D., Mills, W. J., Moore, W., Moukaddam, M., Olaizola, B., Peters, E. E., Radich, A. J., Rand, E. T., Sarazin, F., Svensson, C. E., Williams, S. J., and Yates, S. W.

Subjects
Nuclear Experiment
Abstract

The $\beta^-$ decay of $^{47}$K to $^{47}$Ca is an appropriate mechanism for benchmarking interactions spanning the $sd$ and $pf$ shells, but current knowledge of the $\beta^-$-decay scheme is limited. We have performed a high-resolution, high-efficiency study of the $\beta^-$-decay of $^{47}$K with the GRIFFIN spectrometer at TRIUMF-ISAC. The study revealed 48 new transitions, a more precise value for the $^{47}$K half-life (17.38(3)~s), and new spin and parity assignments for eight excited states. Levels placed for the first time here raise the highest state observed in $\beta^-$ decay to within 568(3) keV of the $Q$-value and confirm the previously measured large $\beta^-$-decay branching ratios to the low-lying states. Previously unobserved $\beta^-$-feeding to 3/2$^+$ states between 4.5 and 6.1~MeV excitation energy was identified with a total $\beta^-$-feeding intensity of 1.29(2)\%. The sum of the $B(GT)$ values for these states indicates that the $1s_{1/2}$ proton hole strength near this excitation energy is comparable to the previously known $1s_{1/2}$ proton and neutron hole strengths near 2.6 MeV.

Published
2020
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8. Absence of Low-Energy Shape Coexistence in $^{80}$Ge: The Nonobservation of a Proposed Excited 0$_2^+$ Level at 639 keV

Author

Garcia, F. H., Andreoiu, C., Ball, G. C., Bell, A., Garnsworthy, A. B., Nowacki, F., Petrache, C. M., Poves, A., Whitmore, K., Ali, F. A., Bernier, N., Bhattacharjee, S. S., Bowry, M., Coleman, R. J., Dillmann, I., Djianto, I., Forney, A. M., Gascoine, M., Hackman, G., Leach, K. G., Murphy, A. N., Natzke, C. R., Olaizola, B., Ortner, K., Peters, E. E., Rajabali, M. M., Raymond, K., Svensson, C. E., Umashankar, R., Williams, J., and Yates, D.

Subjects
Nuclear Experiment
Abstract

The $^{80}$Ge structure was investigated in a high-statistics $\beta$-decay experiment of $^{80}$Ga using the GRIFFIN spectrometer at TRIUMF-ISAC through $\gamma$, $\beta$-$e$, $e$-$\gamma$ and $\gamma$-$\gamma$ spectroscopy. No evidence was found for the recently reported 0$_2^{+}$ 639-keV level suggested as evidence for low-energy shape coexistence in $^{80}$Ge. Large-scale shell model calculations performed in $^{78,80,82}$Ge place the $0^{+}_{2}$ level in $^{80}$Ge at 2\,MeV. The new experimental evidence combined with shell model predictions indicate that low-energy shape coexistence is not present in $^{80}$Ge.

Published
2020
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9. $E0$ transition strength in stable Ni isotopes

Author

Evitts, L. J., Garnsworthy, A. B., Kibedi, T., Smallcombe, J., Reed, M. W., Stuchbery, A. E., Lane, G. J., Eriksen, T. K., Akber, A., Alshahrani, B., de Vries, M., Gerathy, M. S. M., Holt, J. D., Lee, B. Q., McCormick, B. P., Mitchell, A. J., Moukaddam, M., Mukhopadhyay, S., Palalani, N., Palazzo, T., Peters, E. E., Ramirez, A. P. D., Tornyi, T., and Yates, S. W.

Subjects
Nuclear Experiment
Abstract

Excited states in $^{58,60,62}$Ni were populated via inelastic proton scattering at the Australian National University as well as via inelastic neutron scattering at the University of Kentucky Accelerator Laboratory. The Super-e electron spectrometer and the CAESAR Compton-suppressed HPGe array were used in complementary experiments to measure conversion coefficients and $\delta(E2/M1)$ mixing ratios, respectively, for a number of $2^+ \rightarrow 2^+$ transitions. The data obtained were combined with lifetimes and branching ratios to determine $E0$, $M1$, and $E2$ transition strengths between $2^+$ states. The $E0$ transition strengths between $0^+$ states were measured using internal conversion electron spectroscopy and compare well to previous results from internal pair formation spectroscopy. The $E0$ transition strengths between the lowest-lying $2^+$ states were found to be consistently large for the isotopes studied.

Published
2019

10. Detailed spectroscopy of $^{46}$Ca: A study of the $\beta^-$ decay of $^{46}$K

Author

Pore, J. L., Andreoiu, C., Smith, J. K., MacLean, A. D., Chester, A., Holt, J. D., Ball, G. C., Bender, P. C., Bildstein, V., Braid, R., Varela, A. Diaz, Dunlop, R., Evitts, L. J., Garnsworthy, A. B., Garrett, P. E., Hackman, G., Ilyushkin, S. V., Jigmeddorj, B., Kuhn, K., Kunz, P., Laffoley, A. T., Leach, K. G., Miller, D., Mills, W. J., Moore, W., Moukaddam, M., Morrison, L. N., Olaizola, B., Peters, E. E., Radich, A. J., Rand, E. T., Sarazin, F., Southall, D., Svensson, C. E., Williams, S. J., and Yates, S. W.

Subjects
Nuclear Experiment
Abstract

We report on high-statistics data from the $\beta^-$ decay of the $^{46}$K $J^{\pi}$ = 2$^-$ ground state taken with the GRIFFIN spectrometer located at the TRIUMF-ISAC facility. In total, 199 $\gamma$ rays and 42 excited states were placed in the level scheme, and from the observed $\beta$ feeding and angular correlations of pairs of cascading $\gamma$ rays, it was possible to assign spins and parities to excited states and determine mixing ratios for selected $\gamma$ rays. The level structure of $^{46}$Ca is compared to theoretical predictions from a microscopic valence-space Hamiltonian derived from two- (NN) and three-nucleon (3N) forces. These calculations are in reasonable agreement with the experimental data and indicate that the protons in this region are not as inert as would be expected for semi-magic nuclei.

Published
2019
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11. Emerging collectivity from the nuclear structure of $^{132}$Xe: Inelastic neutron scattering studies and shell-model calculations

Author

Peters, E. E., Stuchbery, A. E., Chakraborty, A., Crider, B. P., Ashley, S. F., Kumar, A., McEllistrem, M. T., Prados-Estévez, F. M., and Yates, S. W.

Subjects
Nuclear Experiment, Nuclear Theory
Abstract

Inelastic neutron scattering was used to study the low-lying nuclear structure of $^{132}$Xe. A comprehensive level scheme is presented, as well as new level lifetimes, multipole mixing ratios, branching ratios, and transition probabilities. Comparisons of these data as well as previously measured $E2$ strengths and $g$ factors are made with new shell-model calculations for $^{132,134,136}$Xe to explore the emergence of collectivity in the Xe isotopes with $N$ < 82 near the closed shell.

Published
2019
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12. Conceptual design and first results for a neutron detector with interaction localization capabilities

Author

Heideman, J., Perez-Loureiro, D., Grzywacz, R., Thornsberry, C. R., Chan, J., Heilbronn, L. H., Neupane, S. K., Schmitt, K., Rajabali, M. M., Engelhardt, A. R., Howell, C. W., Mostella, L. D., Owens, J. S., Shadrick, S. C., Peters, E. E., Ramirez, A. P. D., Yates, S. W., and Vaigneur, K.

Subjects
Physics - Instrumentation and Detectors
Abstract

A new high-precision detector for studying neutrons from beta-delayed neutron emission and direct reaction studies is proposed. The Neutron dEtector with Xn Tracking (NEXT) array is designed to maintain high intrinsic neutron detection efficiency while reducing uncertainties in neutron energy measurements. A single NEXT module is composed of thin segments of plastic scintillator, each optically separated, capable of neutron-gamma discrimination. Each segmented module is coupled to position sensitive photodetectors enabling the high-precision determination of neutron time of arrival and interaction position within the active volume. A design study has been conducted based on simulations and experimental tests leading to the construction of prototype units. First results from measurements using a $^{252}$Cf neutron source and accelerator-produced monoenergetic neutrons are presented., Comment: 17 pages, 21 Figures

Published
2019
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13. Photo-response of the N=Z24 nucleus N=Z24Mg

Author

Deary, J., Scheck, M., Schwengner, R., O’Donnell, D., Bemmerer, D., Beyer, R., Hensel, Th., Junghans, A. R., Kögler, T., Müller, S. E., Römer, K., Schmidt, K., Turkat, S., Urlaß, S., Wagner, A., Bowry, M., Adsley, P., Agar, O., Chapman, R., Crespi, F. C. L., Doherty, D. T., Gayer, U. Friman, Herzberg, R.-D., Isaak, J., Janssens, R. V. F., Kröll, T., Löher, B., Nara Singh, B. S., von Neumann-Cosel, P., Pellegri, L., Peters, E. E., Rainovski, G., Savran, D., Smith, J. F., Spieker, M., Thirolf, P. G., Triambak, S., Tornow, W., Venhart, M., Wiedeking, M., Wieland, O., Yates, S. W., and Zilges, A.

Published
2023
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14. The GRIFFIN Facility for Decay-Spectroscopy Studies at TRIUMF-ISAC

Author

Garnsworthy, A. B., Svensson, C. E., Bowry, M., Dunlop, R., MacLean, A. D., Olaizola, B., Smith, J. K., Ali, F. A., Andreoiu, C., Ash, J. E., Ashfield, W. H., Ball, G. C., Ballast, T., Bartlett, C., Beadle, Z., Bender, P. C., Bernier, N., Bhattacharjee, S. S., Bidaman, H., Bildstein, V., Bishop, D., Boubel, P., Braid, R., Brennan, D., Bruhn, T., Burbadge, C., Cheeseman, A., Chester, A., Churchman, R., Ciccone, S., Caballero-Folch, R., Cross, D. S., Cruz, S., Davids, B., Varela, A. Diaz, Dillmann, I., Dunlop, M. R., Evitts, L. J., Garcia, F. H., Garrett, P. E., Georges, S., Gillespie, S., Gudapati, R., Hackman, G., Hadinia, B., Hallam, S., Henderson, J., Ilyushkin, S. V., Jigmeddorj, B., Kilic, A. I., Kisliuk, D., Kokke, R., Kuhn, K., Kruecken, R., Kuwabara, M., Laffoley, A. T., Lafleur, R., Leach, K. G., Leslie, J. R., Linn, Y., Lim, C., MacConnachie, E., Mathews, A. R., McGee, E., Measures, J., Miller, D., Mills, W. J., Moore, W., Morris, D., Morrison, L. N., Moukaddam, M., Natzke, C. R., Ortner, K., Padilla-Rodal, E., Paetkau, O., Park, J., Patel, H. P., Pearson, C. J., Peters, E., Peters, E. E., Pore, J. L., Radich, A. J., Rajabali, M. M., Rand, E. T., Raymond, K., Rizwan, U., Ruotsalainen, P., Saito, Y., Sarazin, F., Shaw, B., Smallcombe, J., Southall, D., Starosta, K., Ticu, M., Timakova, E., Turko, J., Umashankar, R., Unsworth, C., Wang, Z. M., Whitmore, K., Wong, S., Yates, S. W., Zganjar, E. F., and Zidar, T.

Subjects
Physics - Instrumentation and Detectors, Nuclear Experiment
Abstract

Gamma-Ray Infrastructure For Fundamental Investigations of Nuclei, GRIFFIN, is a new high-efficiency $\gamma$-ray spectrometer designed for use in decay spectroscopy experiments with low-energy radioactive ion beams provided by TRIUMF's Isotope Separator and Accelerator (ISAC-I) facility. GRIFFIN is composed of sixteen Compton-suppressed large-volume clover-type high-purity germanium (HPGe) $\gamma$-ray detectors combined with a suite of ancillary detection systems and coupled to a custom digital data acquisition system. The infrastructure and detectors of the spectrometer as well as the performance characteristics and the analysis techniques applied to the experimental data are described.

Published
2018
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15. In-beam internal conversion electron spectroscopy with the SPICE detector

Author

Moukaddam, M., Smallcombe, J., Evitts, L. J., Garnsworthy, A. B., Andreoiu, C., Ball, G. C., Berean-Dutcher, J., Bishop, D., Bolton, C., Caballero-Folch, R., Constable, M., Cross, D. S., Drake, T. E., Dunlop, R., Garrett, P. E., Georges, S., Hackman, G., Hallam, S., Henderson, J., Henderson, R., Krücken, R., Kurchaninov, L., Kurkjian, A., Olaizola, B., O'Sullivan, E., Lu, P., Park, J., Peters, E. E., Pore, J. L., Rand, E. T., Ruotsalainen, P., Smith, J. K., Southall, D., Spencer, M., Svensson, C. E., Wiens, M., Williams, M., Yates, S. W., and Zidar, T.

Subjects
Physics - Instrumentation and Detectors
Abstract

The SPectrometer for Internal Conversion Electrons (SPICE) has been commissioned for use in conjunction with the TIGRESS $\gamma$-ray spectrometer at TRIUMF's ISAC-II facility. SPICE features a permanent rare-earth magnetic lens to collect and direct internal conversion electrons emitted from nuclear reactions to a thick, highly segmented, lithium-drifted silicon detector. This arrangement, combined with TIGRESS, enables in-beam $\gamma$-ray and internal conversion electron spectroscopy to be performed with stable and radioactive ion beams. Technical aspects of the device, capabilities, and initial performance are presented.

Published
2018
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16. Identification of significant $E0$ strength in the $2^+_2 \rightarrow 2^+_1$ transitions of $^{58, 60, 62}$Ni

Author

Evitts, L. J., Garnsworthy, A. B., Kibédi, T., Smallcombe, J., Reed, M. W., Brown, B. A., Stuchbery, A. E., Lane, G. J., Eriksen, T. K., Akber, A., Alshahrani, B., de Vries, M., Gerathy, M. S. M., Holt, J. D., Lee, B. Q., McCormick, B. P., Mitchell, A. J., Moukaddam, M., Mukhopadhyay, S., Palalani, N., Palazzo, T., Peters, E. E., Ramirez, A. P. D., Stroberg, S. R., Tornyi, T., and Yates, S. W.

Subjects
Nuclear Experiment, Nuclear Theory
Abstract

The $E0$ transition strength in the $2^+_2 \rightarrow 2^+_1$ transitions of $^{58,60,62}$Ni have been determined for the first time following a series of measurements at the Australian National University (ANU) and the University of Kentucky (UK). The CAESAR Compton-suppressed HPGe array and the Super-e solenoid at ANU were used to measure the $\delta(E2/M1)$ mixing ratio and internal conversion coefficient of each transition following inelastic proton scattering. Level half-lives, $\delta(E2/M1)$ mixing ratios and $\gamma$-ray branching ratios were measured at UK following inelastic neutron scattering. The new spectroscopic information was used to determine the $E0$ strengths. These are the first $2^+ \rightarrow 2^+$ $E0$ transition strengths measured in nuclei with spherical ground states and the $E0$ component is found to be unexpectedly large; in fact, these are amongst the largest $E0$ transition strengths in medium and heavy nuclei reported to date.

Published
2018
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17. Lifetimes of 0$$^+$$ states in $$^{162}$$Dy

Author

Aprahamian, A., primary, Casarella, C., additional, Lesher, S. R., additional, Lee, K., additional, Crider, B. P., additional, Meier, M. M., additional, Peters, E. E., additional, Prados-Estévez, F. M., additional, and Tully, Z., additional

Published
2024
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18. The electric dipole response of $^{76}$Se above 4 MeV

Author

Goddard, P. M., Cooper, N., Werner, V., Rusev, G., Stevenson, P. D., Rios, A., Bernards, C., Chakraborty, A., Crider, B. P., Kelley, J. H., Kwan, E., Glorius, J., Peters, E. E., Pietralla, N., Raut, R., Romig, C., Savran, D., Schnorrenberger, L., Smith, M. K., Sonnabend, K., Tonchev, A. P., Tornow, W., and Yates, S. W.

Subjects
Nuclear Experiment, Nuclear Theory
Abstract

The dipole response of $^{76}_{34}$Se in the energy range 4 to 9 MeV has been analyzed using a $(\vec\gamma,{\gamma}')$ polarized photon scattering technique, performed at the High Intensity $\gamma$-Ray Source facility, to complement previous work performed using unpolarized photons. The results of this work offer both an enhanced sensitivity scan of the dipole response and an unambiguous determination of the parities of the observed J=1 states. The dipole response is found to be dominated by $E1$ excitations, and can reasonably be attributed to a pygmy dipole resonance. Evidence is presented to suggest that a significant amount of directly unobserved excitation strength is present in the region, due to unobserved branching transitions in the decays of resonantly excited states. The dipole response of the region is underestimated when considering only ground state decay branches. We investigate the electric dipole response theoretically, performing calculations in a 3D cartesian-basis time-dependent Skyrme-Hartree-Fock framework., Comment: 20 pages, 18 figures, to be submitted to PRC

Published
2013
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19. Photo-response of the $$N=Z$$ nucleus $$^{24}$$Mg

Author

Deary, J., primary, Scheck, M., additional, Schwengner, R., additional, O’Donnell, D., additional, Bemmerer, D., additional, Beyer, R., additional, Hensel, Th., additional, Junghans, A. R., additional, Kögler, T., additional, Müller, S. E., additional, Römer, K., additional, Schmidt, K., additional, Turkat, S., additional, Urlaß, S., additional, Wagner, A., additional, Bowry, M., additional, Adsley, P., additional, Agar, O., additional, Chapman, R., additional, Crespi, F. C. L., additional, Doherty, D. T., additional, Gayer, U. Friman, additional, Herzberg, R.-D., additional, Isaak, J., additional, Janssens, R. V. F., additional, Kröll, T., additional, Löher, B., additional, Nara Singh, B. S., additional, von Neumann-Cosel, P., additional, Pellegri, L., additional, Peters, E. E., additional, Rainovski, G., additional, Savran, D., additional, Smith, J. F., additional, Spieker, M., additional, Thirolf, P. G., additional, Triambak, S., additional, Tornow, W., additional, Venhart, M., additional, Wiedeking, M., additional, Wieland, O., additional, Yates, S. W., additional, and Zilges, A., additional

Published
2023
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20. Firm spin and parity assignments for high-lying, low-spin levels in stable Si isotopes

Author

Sinclair, J., Scheck, M., Finch, S. W., Krishichayan, Friman-Gayer, U., Tornow, W., Battaglia, G., Beck, T., Chapman, R., Chishti, M. M. R., Fransen, Ch., Gonzales, R., Hoemann, E., Isaak, J., Janssens, R. V. F., Jaroszynski, D. A., Johnson, S., Jones, M. D., Keatings, J. M., Kelly, N., Kleemann, J., Little, D., Löher, B., Mashtakov, K. R., Müscher, M., O’Donnell, D., Papst, O., Peters, E. E., Savran, D., Schilling, M., Schwengner, R., Spagnoletti, P., Spieker, M., Werner, V., Wilhelmy, J., Wieland, O., Yates, S. W., and Zilges, A.

Published
2020
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21. Lifetimes of 0+ states in 162Dy.

Author

Aprahamian, A., Casarella, C., Lesher, S. R., Lee, K., Crider, B. P., Meier, M. M., Peters, E. E., Prados-Estévez, F. M., and Tully, Z.

Abstract

Transfer reactions at the high-precision Q3D spectrometer at the University of Munich have shown that there are many low-lying excited K π = 0 + states in well-deformed nuclei. A recent study of 162 Dy shows eleven 0 + states below an energy of 3 MeV. While this nucleus is studied extensively, the lifetimes of the new states were not known. We report on lifetime measurements of the newly observed states in order to determine their properties and allow the characterization of these states. Level lifetimes of 0 + states in 162 Dy were measured by the ( n , n ′ γ ) reaction and the Doppler-shift attenuation method at the University of Kentucky. This work allow us to report the transition probabilities from six of the eleven 0 + states. We suggest that the first excited K π = 0 + excitation at 1400.2 keV in 162 Dy may be the β vibrational excitation and not the γ γ excitation indicated in the past or a shape coexistence minimum. [ABSTRACT FROM AUTHOR]

Published
2024
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22. E0 transition strengths in 110Pd

Author

Smallcombe, J., Berean-Dutcher, J., Moukaddam, M., Garnsworthy, A. B., Andreoiu, C., Caballero-Folch, R., Drake, T. E., Evitts, L. J., Hackman, G., Henderson, J., Kurkjian, A., Olaizola, B., Peters, E. E., Southall, D., Ruotsalainen, P., Svensson, C. E., Wiens, M., Yates, S. W., and Zidar, T.

Published
2018
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24. Lifetime measurements of 0+ states in Er168 with the Doppler-shift attenuation method

Author

Lesher, S. R., primary, Aprahamian, A., additional, Lee, K., additional, Alemayehu, B., additional, Clark, L. M., additional, James, X., additional, Lowrie, J. C. T., additional, Meier, M., additional, McEwan, L., additional, Mukhopadhyay, S., additional, Peters, E. E., additional, Ramirez, A. P. D., additional, Ryan, M., additional, Rice, B. G., additional, Stratman, A., additional, Temanson, E., additional, Vanhoy, J. R., additional, and Yates, S. W., additional

Published
2022
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27. Spectroscopic study of Ca47 from the β− decay of K47

Author

Smith, J. K., primary, Garnsworthy, A. B., additional, Pore, J. L., additional, Andreoiu, C., additional, MacLean, A. D., additional, Chester, A., additional, Beadle, Z., additional, Ball, G. C., additional, Bender, P. C., additional, Bildstein, V., additional, Braid, R., additional, Varela, A. Diaz, additional, Dunlop, R., additional, Evitts, L. J., additional, Garrett, P. E., additional, Hackman, G., additional, Ilyushkin, S. V., additional, Jigmeddorj, B., additional, Kuhn, K., additional, Laffoley, A. T., additional, Leach, K. G., additional, Miller, D., additional, Mills, W. J., additional, Moore, W., additional, Moukaddam, M., additional, Olaizola, B., additional, Peters, E. E., additional, Radich, A. J., additional, Rand, E. T., additional, Sarazin, F., additional, Svensson, C. E., additional, Williams, S. J., additional, and Yates, S. W., additional

Published
2020
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28. Absence of Low-Energy Shape Coexistence in Ge80 : The Nonobservation of a Proposed Excited 02+ Level at 639 keV

Author

Garcia, F. H., primary, Andreoiu, C., additional, Ball, G. C., additional, Bell, A., additional, Garnsworthy, A. B., additional, Nowacki, F., additional, Petrache, C. M., additional, Poves, A., additional, Whitmore, K., additional, Ali, F. A., additional, Bernier, N., additional, Bhattacharjee, S. S., additional, Bowry, M., additional, Coleman, R. J., additional, Dillmann, I., additional, Djianto, I., additional, Forney, A. M., additional, Gascoine, M., additional, Hackman, G., additional, Leach, K. G., additional, Murphy, A. N., additional, Natzke, C. R., additional, Olaizola, B., additional, Ortner, K., additional, Peters, E. E., additional, Rajabali, M. M., additional, Raymond, K., additional, Svensson, C. E., additional, Umashankar, R., additional, Williams, J., additional, and Yates, D., additional

Published
2020
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29. Absence of Low-Energy Shape Coexistence in $^{80}\mathrm{Ge}$: The Nonobservation of a Proposed Excited ${0}_{2}^{+}$ Level at 639 keV

Author

Garcia, F. H., Andreoiu, C., Ball, G. C., Bell, A., Garnsworthy, A. B., Nowacki, F., Petrache, C. M., Poves, A., Whitmore, K., Ali, F. A., Bernier, N., Bhattacharjee, S. S., Bowry, M., Coleman, R. J., Dillmann, I., Djianto, I., Forney, A. M., Gascoine, M., Hackman, G., Leach, K. G., Murphy, A. N., Natzke, C. R., Olaizola, B., Ortner, K., Peters, E. E., Rajabali, M. M., Raymond, K., Svensson, C. E., Umashankar, R., Williams, J., Yates, D., Institut Pluridisciplinaire Hubert Curien (IPHC), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université de Strasbourg (UNISTRA)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Physique des 2 Infinis Irène Joliot-Curie (IJCLab), and Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)

Subjects
FOS: Physical sciences, Nuclear Experiment (nucl-ex), [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Nuclear Experiment, Nuclear Physics
Abstract

The $^{80}$Ge structure was investigated in a high-statistics $\beta$-decay experiment of $^{80}$Ga using the GRIFFIN spectrometer at TRIUMF-ISAC through $\gamma$, $\beta$-$e$, $e$-$\gamma$ and $\gamma$-$\gamma$ spectroscopy. No evidence was found for the recently reported 0$_2^{+}$ 639-keV level suggested as evidence for low-energy shape coexistence in $^{80}$Ge. Large-scale shell model calculations performed in $^{78,80,82}$Ge place the $0^{+}_{2}$ level in $^{80}$Ge at 2\,MeV. The new experimental evidence combined with shell model predictions indicate that low-energy shape coexistence is not present in $^{80}$Ge.

Published
2020
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30. Delta K=0 M1 Excitation Strength of the Well-Deformed Nucleus Dy-164 from K Mixing

Author

Beck, T., Werner, V, Pietralla, N., Bhike, M., Cooper, N., Friman-Gayer, U., Isaak, J., Jolos, R., V, Kleemann, J., Papst, O., Tornow, W., Bernards, C., Crider, B. P., Ilieva, R. S., Loher, B., Mihai, C., Naqvi, F., Pascu, S., Peters, E. E., Prados-Estevez, F. M., Ross, T. J., Savran, D., Vanhoy, J. R., Zilges, A., Beck, T., Werner, V, Pietralla, N., Bhike, M., Cooper, N., Friman-Gayer, U., Isaak, J., Jolos, R., V, Kleemann, J., Papst, O., Tornow, W., Bernards, C., Crider, B. P., Ilieva, R. S., Loher, B., Mihai, C., Naqvi, F., Pascu, S., Peters, E. E., Prados-Estevez, F. M., Ross, T. J., Savran, D., Vanhoy, J. R., and Zilges, A.

Abstract

The size of a Delta K = 0 M1 excitation strength has been determined for the first time in a predominantly axially deformed even-even nucleus. It has been obtained from the observation of a rare K-mixing situation between two close-lying J(pi) = 1(+) states of the nucleus Dy-164 with components characterized by intrinsic projection quantum numbers K = 0 and K = 1. Nuclear resonance fluorescence induced by quasimonochromatic linearly polarized gamma-ray beams provided evidence for K mixing of the 1(+) states at 3159.1(3) and 3173.6(3) keV in excitation energy from their gamma-decay branching ratios into the ground-state band. The Delta K = 0 transition strength of B(M1;0(1)(+) -> 1(K=0)(+) = 0.008(1)mu(2)(N) was inferred from a mixing analysis of their M1 transition rates into the ground-state band. It is in agreement with predictions from the quasiparticle phonon nuclear model. This determination represents first experimental information on the M1 excitation strength of a nuclear quantum state with a negative R-symmetry quantum number.

Published
2020

32. Relevance of the Nuclear Structure of the Stable Ge Isotopes to the Neutrino-less Double-Beta Decay of 76Ge.

Author

Mitchell, A.J., Pavetich, S., Koll, D., Yates, S. W., Peters, E. E., Crider, B. P., Mukhopadhyay, S., and Ramirez, A. P. D.

Subjects
NUCLEAR structure, ISOTOPES, DOPPLER effect, INELASTIC neutron scattering, NEUTRINOLESS double beta decay
Abstract

Gamma-ray detection following the inelastic neutron scattering reaction on isotopically enriched material was used to study the nuclear structure of 74Ge. From these measurements, low-lying, low-spin excited states were characterized, new states and their decays were identified, level lifetimes were measured with the Doppler-shift attenuation method (DSAM), multipole mixing ratios were established, and transition probabilities were determined. New structural features in 74Ge were identified, and the reanalysis of older 76Ge data led to the placement of the 2+ member of the intruder band. In addition, a number of previously placed states in 74Ge were shown not to exist. A procedure for future work, which will lead to meaningful data for constraining calculations of the neutrinoless double-beta decay matrix element, is suggested. [ABSTRACT FROM AUTHOR]

Published
2020
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33. Detailed spectroscopy of Ca46 : A study of the β− decay of K46

Author

Pore, J. L., primary, Andreoiu, C., additional, Smith, J. K., additional, MacLean, A. D., additional, Chester, A., additional, Holt, J. D., additional, Ball, G. C., additional, Bender, P. C., additional, Bildstein, V., additional, Braid, R., additional, Diaz Varela, A., additional, Dunlop, R., additional, Evitts, L. J., additional, Garnsworthy, A. B., additional, Garrett, P. E., additional, Hackman, G., additional, Ilyushkin, S. V., additional, Jigmeddorj, B., additional, Kuhn, K., additional, Kunz, P., additional, Laffoley, A. T., additional, Leach, K. G., additional, Miller, D., additional, Mills, W. J., additional, Moore, W., additional, Moukaddam, M., additional, Morrison, L. N., additional, Olaizola, B., additional, Peters, E. E., additional, Radich, A. J., additional, Rand, E. T., additional, Sarazin, F., additional, Southall, D., additional, Svensson, C. E., additional, Williams, S. J., additional, and Yates, S. W., additional

Published
2019
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35. Emerging collectivity from the nuclear structure of Xe 132: Inelastic neutron scattering studies and shell-model calculations

Author

Peters, E. E., Stuchbery, Andrew, Chakraborty, A., Crider, B. P., Ashley, S. F., Kumar, A., McEllistrem, M. T., Prados-Estevez, F. M., Yates, S.W., Peters, E. E., Stuchbery, Andrew, Chakraborty, A., Crider, B. P., Ashley, S. F., Kumar, A., McEllistrem, M. T., Prados-Estevez, F. M., and Yates, S.W.

Abstract

Inelastic neutron scattering was used to study the low-lying nuclear structure of 132Xe. A comprehensive level scheme is presented, as well as new level lifetimes, multipole mixing ratios, branching ratios, and transition probabilities. Comparisons of these data as well as previously measured E2 strengths and g factors are made with new shell-model calculations for 132, 134, 136 Xe to explore the emergence of collectivity in the Xe isotopes with N<82 near the closed shell.

Published
2019

36. E0 transition strength in stable Ni isotopes

Author

Evitts, L. J., primary, Garnsworthy, A. B., additional, Kibédi, T., additional, Smallcombe, J., additional, Reed, M. W., additional, Stuchbery, A. E., additional, Lane, G. J., additional, Eriksen, T. K., additional, Akber, A., additional, Alshahrani, B., additional, de Vries, M., additional, Gerathy, M. S. M., additional, Holt, J. D., additional, Lee, B. Q., additional, McCormick, B. P., additional, Mitchell, A. J., additional, Moukaddam, M., additional, Mukhopadhyay, S., additional, Palalani, N., additional, Palazzo, T., additional, Peters, E. E., additional, Ramirez, A. P. D., additional, Tornyi, T., additional, and Yates, S. W., additional

Published
2019
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37. Inelastic neutron scattering studies of Se76

Author

Mukhopadhyay, S., primary, Crider, B. P., additional, Brown, B. A., additional, Chakraborty, A., additional, Kumar, A., additional, McEllistrem, M. T., additional, Peters, E. E., additional, Prados-Estévez, F. M., additional, and Yates, S. W., additional

Published
2019
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39. Probing the low-lying level structure of 94Zr through β- decay.

Author

Mandal, K., Mondal, A. K., Chakraborty, A., Peters, E. E., Crider, B. P., Andreoiu, C., Bender, P. C., Cross, D. S., Demand, G. A., Garnsworthy, A. B., Garrett, P. E., Hackman, G., Hadinia, B., Ketelhut, S., Kumar, Ajay, Leach, K. G., McEllistrem, M. T., Pore, J., Prados-Estévez, F. M., and Rand, E. T.

Subjects
BRANCHING ratios, ZIRCONIUM isotopes, QUADRUPOLES, NUCLEAR structure, RADIOACTIVE decay
Abstract

Low-lying states of 94Zr are populated following - decay of 94Y, and the emitted rays from 94Zr are detected using the 8p spectrometer composed of 20 Compton-suppressed HPGe detectors. High- statistics coincidence data have been used for the placement of very weak decay branches in the level scheme. Combining the results of level lifetimes from a previous experiment and the precisely measured branching ratio values of the weak decay branches from the present experiment, it is possible to extract the B(E2) values for all the possible decay branches from a given level. These values are helpful for proper identification of the collective and non-collective states of 94Zr. The experimental findings have been compared with predictions from shell-model calculations with a limited valence space; however, these calculations are inadequate in reproducing all of the measured spectroscopic quantities. [ABSTRACT FROM AUTHOR]

Published
2020

40. Seniority structure of Xe82136

Author

Peters, E. E., primary, Van Isacker, P., additional, Chakraborty, A., additional, Crider, B. P., additional, Kumar, A., additional, Liu, S. H., additional, McEllistrem, M. T., additional, Mehl, C. V., additional, Prados-Estévez, F. M., additional, Ross, T. J., additional, Wood, J. L., additional, and Yates, S. W., additional

Published
2018
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41. Undergraduate Education at the University of Kentucky Accelerator Laboratory.

Author

Ramirez, A. P. D., Alemayehu, B., Lowrie, J., Hicks, S. F., Vanhoy, J. R., McEllistrem, M. T., Mukhopadhyay, S., Peters, E. E., and Yates, S. W.

Subjects
NUCLEAR research, MOLTEN salt reactors, INELASTIC neutron scattering, NEUTRON counters, NEUTRON scattering, NEUTRON temperature, NEUTRON sources
Abstract

The University of Kentucky accelerator laboratory provides undergraduate students an opportunity to experience scientific research in nuclear physics. They are introduced to our research program, which focuses on the examination of basic nuclear properties using the 7 MV CN Van de Graaff accelerator and the time-of-flight facility to perform inelastic neutron scattering measurements with γ-ray and neutron detection. Students are given a series of projects to support the measurements including experimental equipment setup, kinematic calculations, data collection, experimental diagnostics, MCNP simulations, analysis code development, and preliminary analysis of the data. Undergraduate physics majors from the University of Dallas took part in (n,n′γ) measurements for LiF. Neutron scattering cross sections for these nuclei, which are of significant interest in coolant designs for molten salt reactors, were determined for incident neutron energies between 0.8 and 4.5 MeV. By measuring the γ-ray production cross sections and feeding contributions from higher-lying levels, students extracted the neutron level cross sections for Li and F. Additional (n,n′) measurements for Li metal will be performed in the near future to supplement the γ-ray data. [ABSTRACT FROM AUTHOR]

Published
2019
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43. Lifetime measurements of low-spin negative-parity levels in Gd160

Author

Lesher, S. R., primary, Casarella, C., additional, Aprahamian, A., additional, Robledo, L. M., additional, Crider, B. P., additional, Ikeyama, R., additional, Marsh, I. R., additional, McEllistrem, M. T., additional, Peters, E. E., additional, Prados-Estévez, F. M., additional, Smith, M. K., additional, Tully, Z. R., additional, Vanhoy, J. R., additional, and Yates, S. W., additional

Published
2017
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44. Neutron scattering cross section measurements forFe56

Author

Ramirez, A. P. D., primary, Vanhoy, J. R., additional, Hicks, S. F., additional, McEllistrem, M. T., additional, Peters, E. E., additional, Mukhopadhyay, S., additional, Harrison, T. D., additional, Howard, T. J., additional, Jackson, D. T., additional, Lenzen, P. D., additional, Nguyen, T. D., additional, Pecha, R. L., additional, Rice, B. G., additional, Thompson, B. K., additional, and Yates, S. W., additional

Published
2017
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45. Collective quadrupole behavior in Pd106

Author

Prados-Estévez, F. M., primary, Peters, E. E., additional, Chakraborty, A., additional, Mynk, M. G., additional, Bandyopadhyay, D., additional, Boukharouba, N., additional, Choudry, S. N., additional, Crider, B. P., additional, Garrett, P. E., additional, Hicks, S. F., additional, Kumar, A., additional, Lesher, S. R., additional, McKay, C. J., additional, McEllistrem, M. T., additional, Mukhopadhyay, S., additional, Orce, J. N., additional, Scheck, M., additional, Vanhoy, J. R., additional, Wood, J. L., additional, and Yates, S. W., additional

Published
2017
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48. 0+states inXe130,132: A search for E(5) behavior

Author

Peters, E. E., primary, Ross, T. J., additional, Ashley, S. F., additional, Chakraborty, A., additional, Crider, B. P., additional, Hennek, M. D., additional, Liu, S. H., additional, McEllistrem, M. T., additional, Mukhopadhyay, S., additional, Prados-Estévez, F. M., additional, Ramirez, A. P. D., additional, Thrasher, J. S., additional, and Yates, S. W., additional

Published
2016
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49. Inspection of 56Fe γ-Ray angular distributions as a function of incident neutron energy using optical model approaches.

Author

Vanhoy, J. R., Ramirez, A. P., Alcorn-Dominguez, D. K., Hicks, S. F., Peters, E. E., McEllistrem, M. T., Mukhopadhyay, S., and Yates, S. W.

Subjects
NEUTRON cross sections, NUCLEAR reactions, NUCLEAR energy, NEUTRON temperature, ANGULAR distribution (Nuclear physics)
Abstract

Neutron inelastic scattering cross sections measured directly through (n,n) or deduced from -ray production cross sections following inelastic neutron scattering (n,n'γ) are a focus of basic and applied research at the University of Kentucky Accelerator Laboratory (www.pa.uky.edu/accelerator). For nuclear data applications, angle-integrated cross sections are desired over a wide range of fast neutron energies. Several days of experimental beam time are required for a data set at each incident neutron energy, which limits the number of angular distributions that can be measured in a reasonable amount of time. Approximations can be employed to generate cross sections with a higher energy resolution, since at 125o, the a2P2 term of the Legendre expansion is identically zero and the a4P4 is assumed to be very small. Provided this assumption is true, a single measurement at 125o would produce the γ-ray production cross section. This project tests these assumptions and energy dependences using the codes CINDY/SCAT and TALYS/ECIS06/SCAT. It is found that care must be taken when interpreting γ-ray excitation functions as cross sections when the incident neutron energy is < 1000?keV above threshold or before the onset of feeding. [ABSTRACT FROM AUTHOR]

Published
2017
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50. Capture cross sections on unstable nuclei.

Author

Tonchev, A. P., Escher, J. E., Scielzo, N., Bedrossian, P., Ilieva, R. S., Humby, P., Cooper, N., Goddard, P. M., Werner, V., Tornow, W., Rusev, G., Kelley, J. H., Pietralla, N., Scheck, M., Savran, D., Löher, B., Yates, S. W., Crider, B. P., Peters, E. E., and Tsoneva, N.

Subjects
NEUTRON capture, NUCLEAR cross sections, NUCLEOSYNTHESIS, HAUSER-Feshbach theory, GAMMA rays, RADIOISOTOPES
Abstract

Accurate neutron-capture cross sections on unstable nuclei near the line of beta stability are crucial for understanding the s-process nucleosynthesis. However, neutron-capture cross sections for short-lived radionuclides are difficult to measure due to the fact that the measurements require both highly radioactive samples and intense neutron sources. Essential ingredients for describing the γ decays following neutron capture are the γ-ray strength function and level densities. We will compare different indirect approaches for obtaining the most relevant observables that can constrain Hauser-Feshbach statistical-model calculations of capture cross sections. Specifically, we will consider photon scattering using monoenergetic and 100% linearly polarized photon beams. Challenges that exist on the path to obtaining neutron-capture cross sections for reactions on isotopes near and far from stability will be discussed. [ABSTRACT FROM AUTHOR]

Published
2017
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