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170 results on '"Stoyer, M.A."'

3. Nuclear shape and structure in neutron-rich 110,111Tc

Author

Luo, Y.X., Hamilton, J.H., Rasmussen, J.O., Ramayya, A.V., Stefanescu, I., Hwang, J.K., Zhu, S.J., Gore, P.M., Jones, E.F., Fong, D., Wu, S.C., Lee, I.Y., Ginter, T.N., Ter-Akopian, G.M., Daniel, A.V., Stoyer, M.A., Donangelo, R., and Gelberg, A.

Subjects
Nuclear physics and radiation physics, Classical and quantum mechanics, general physics, Fission Gamma Spectroscopy Triaxial Rotational Bands
Abstract

The structure of Tc nuclei is extended to the more neutron-rich regions based on measurements of prompt gamma rays from the spontaneous fission of 252Cf at Gammasphere. The level scheme of N=67 neutron-rich (Z=43) 110Tc is established for the first time and that of 111Tc is expanded. The ground-state band of 111Tc reaches the band-crossing region and the new observation of the weakly populated alpha = -1/2 member of the band provides important information of signature splitting. The systematics of band crossings in the isotopic and isotonic chains and a CSM calculation suggest that the band crossing of the gs band of 111Tc is due to alignment of a pair of h11/2 neutrons. The best fit to signature splitting, branching ratios, and excitations of the ground-state band of 111Tc by RTRP model calculations result in a shape of epsilon2 = 0.32 and gamma = -26 deg. for this nucleus. Its triaxiality is larger than that of 107Tc, to indicate increasing triaxiality with increasing neutron number. The identification of the weakly-populated "K+2 satellite" band provides strong evidence for the large triaxiality of 111Tc. In 110Tc the four lowest-lying levels observed are very similar to those in 108Tc. At an excitation of 478.9 keV above the lowest state observed, ten states of a delta I = 1 band are observed. This band is very analogous to the delta I = 1 bands in 106,108Tc, but it has greater signature splitting at higher spins.

Published
2006

4. Shape trends and triaxiality in neutron-rich odd-mass Y and Nb isotopes

Author

Luo, Y.X., Rasmussen, J.O., Gelberg, A., Stefanescu, I., Hamilton, J.H., Ramayya, A.V., Hwang, J.K., Zhu, S.J., Gore, P.M., Fong, D., Jones, E.F., Wu, S.C., Lee, I.Y., Ginter, T.N., Ma, W.C., Ter-Akopian, G.M., Daniel, A.V., Stoyer, M.A., and Donangelo, R.

Subjects
Nuclear physics and radiation physics, Nuclear physics and radiation physics, shape trends triaxiality prompt gamma rays
Abstract

New level schems of Y and Nb isotopes are proposed based on measurements of prompt gamma rays from 252Cf fission at Gammasphere. Shape trends regarding triaxiality and quadrupole deformations are studied.

Published
2004

5. Level structures of 110,111,112,113Rh from gammasphere measurements on 252Cf

Author

Luo, Y.X., Wu, S.C., Gilat, J., Rasmussen, J.O., Hamilton, J.H., Ramayya, A.V., Hwang, J.K., Beyer, C.J., Zhu, S.J., Kormicki, J., Zhang, X.Q., Jones, E.F., Gore, P.M., Lee, I-Yang, Zielinski, P., Folden III, C.M., Ginter, T.N., Fallon, P., Ter-Akopian, G.M., Daniel, A.V., Stoyer, M.A., Cole, J.D., Donangelo, R., Asztalos, S.J., and Gelberg, A.

Subjects
Nuclear physics and radiation physics, Isotopes and radiation sources, rhodium spontaneous fission Gammasphere triaxiality californium
Abstract

Using Gammasphere data on prompt gamma rays from spontaneous fission of 252Cf, we propose energy-level schemes for 110,111,112, & 113Rh (Z=45). The fission-gamma data complement earlier studies of others on beta decay of fission products in that prompt fission gammas mainly populate yrast or near-yrast levels, while beta decay populates lower-spin levels. For the odd-A rhodium nuclei studied here, their ground bands and collective sidebands are compared with model calculations using triaxial-shaped nucleus with one odd quasi-proton. The energies and E2 transition rates are best fit by a shape slightly to the prolate side of maximum triaxiality, namely, gamma = 28 deg. The model calculations also show a K=1/2+ band with energies not in good agreement with a corresponding exerimental band. The experimental 1/2+ band is regarded as an intruder band from a prolate-driving proton orbital 1/2[431] above the Z=50 closed shell. This intruder band, seen in other odd-A Rh isotopes, is probably more deformed and prolate and would not be expected to be fit at the same triaxial shape parameter as the 7/2+ ground band. We observe a band-crossing (backbending) in the odd-A ground bands above spins of about 21/2. The odd-odd nuclei 110 and 112 Rh show mainly a single band with no backbending up to higherfrequency than the backbend in the odd-A isotopes. It is concluded that the backbend is due to alignment of a pair of h11/2 neutrons.

Published
2003

6. Level structures of Rh from gammasphere measurem ents on Cf

Author

Luo, Y.X., Wu, S.C., Gilat, J., Rasmussen, J.O., Hamilton, J.H., Ramayya, A.V., Hwang, J.K., Beyer, C.J., Zhu, S.J., Kormicki, J., Zhang, X.Q., Jones, E.F., Gore, P.M., Lee, I-Yang, Zielinski, P., Folden, C.M., Ginter, T.N., Fallon, P., Ter-Akopian, G.M., Daniel, A.V., Stoyer, M.A., Cole, J.D., Donangelo, R., Asztalos, S.J., and Gelberg, A.

Subjects
rhodium spontaneous fission Gammasphere triaxiality californium
Abstract

Using Gammasphere data on prompt gamma rays from spontaneous fission of 252Cf, we propose energy-level schemes for 110,111,112, & 113Rh (Z=45). The fission-gamma data complement earlier studies of others on beta decay of fission products in that prompt fission gammas mainly populate yrast or near-yrast levels, while beta decay populates lower-spin levels. For the odd-A rhodium nuclei studied here, their ground bands and collective sidebands are compared with model calculations using triaxial-shaped nucleus with one odd quasi-proton. The energies and E2 transition rates are best fit by a shape slightly to the prolate side of maximum triaxiality, namely, gamma = 28 deg. The model calculations also show a K=1/2+ band with energies not in good agreement with a corresponding exerimental band. The experimental 1/2+ band is regarded as an intruder band from a prolate-driving proton orbital 1/2[431] above the Z=50 closed shell. This intruder band, seen in other odd-A Rh isotopes, is probably more deformed and prolate and would not be expected to be fit at the same triaxial shape parameter as the 7/2+ ground band. We observe a band-crossing (backbending) in the odd-A ground bands above spins of about 21/2. The odd-odd nuclei 110 and 112 Rh show mainly a single band with no backbending up to higherfrequency than the backbend in the odd-A isotopes. It is concluded that the backbend is due to alignment of a pair of h11/2 neutrons.

Published
2003

7. Level structure of 141Ba and 139Xe and the level systematics of N=85 even-odd isotones

Author

Luo, Y.X., Rasmussen, J.O., Hamilton, J.H., Ramayya, A.V., Hwang, J.K., Beyer, C.J., Zhu, S.J., Kormicki, J., Zhang, X.Q., Jones, E.F., Gore, P.M., Ginter, T.N., Gregorich, K.E., Lee, I-Yang, Macchiavelli, A.O., Zielinski, P., Folden, C.M., Fallon, P., Ter-Akopian, G.M., Oganessian, Yu.Ts., Daniel, A.V., Stoyer, M.A., Cole, J.D., Donangelo, R., Wu, S.C., and Asztalos, S.J.

Subjects
Gammasphere fission spectroscopy nuclear levels 141Ba. 139Xe
Abstract

New level schemes of $^{141}$Ba and $^{139}$Xe are proposed from the analyses of spontaneous-fission gamma data from our $^{252}$Cf spontaneous fission Gammasphere runs of 1995 and 2000. By analogy with the N = 85 even-odd isotones $^{149}$Gd, $^{147}$Sm, and $^{145}$Nd, spins and parities were assigned to the observed excited states in $^{141}$Ba and $^{139}$Xe. It appears that spherical shell model neutron excitations plus octupolephonons are an appropriate basis at the lower end of the bands. Going to higher spins it is clear that the soft rotor involving valence protons as well as neutrons becomes increasingly important in the configurations. Level systematics in the N = 85 even-odd isotones from Gd(Z=64) through Te(Z=52), are discussed. The excitation systematics and smooth trends of the analogous levels support the spin and parity assignment for excited levels observed in $^{141}$Ba and $^{139}$Xe. The level systematics and the comparison with neighboring even-even isotopes indicate that quadrupole and octupole collectivity play roles in $^{141}$Ba and $^{139}$Xe. From Gd(Z=64) through Te(Z=52), increasing excitation energies of the 13/2$^{+}$ states and lowering relative intensities of the positive parity bands in the N = 85 even-odd isotones may indicate that the octupole strength is becoming weaker for the isotones when approaching the Z = 50 closed shell.

Published
2002

8. Multi-modal mass-asymmetric fission of 178Pt from simultaneous mass-kinetic energy fitting

Author

Swinton-Bland, B.M.A., primary, Buete, J., additional, Hinde, D.J., additional, Dasgupta, M., additional, Tanaka, T., additional, Berriman, A.C., additional, Jeung, D.Y., additional, Banerjee, K., additional, Bezzina, L.T., additional, Carter, I.P., additional, Cook, K.J., additional, Sengupta, C., additional, Simenel, C., additional, Simpson, E.C., additional, and Stoyer, M.A., additional

Published
2023
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10. Multi-modal mass-asymmetric fission of Pt from simultaneous mass-kinetic energy fitting

Author

Swinton-Bland, B.M.A., Buete, J., Hinde, D.J., Dasgupta, M., Tanaka, T., Berriman, A.C., Jeung, D.Y., Banerjee, K., Bezzina, L.T., Carter, I.P., Cook, K.J., Sengupta, C., Simenel, C., Simpson, E.C., and Stoyer, M.A.

Abstract

The observation of mass-asymmetric fission in neutron-deficient $^{180}$Hg dramatically expanded the region of mass-asymmetric fission found across the nuclide chart, and has led to intense experimental and theoretical investigations into the fission of sub-lead nuclei. In particular, two major questions have been raised: how many fission modes are present in the fission of sub-lead nuclides, and which shells dictate these modes?Notably, investigations of the fission modes of $^{178}$Pt have led to contrasting results. To solve this disparity, new high-statistics data have been measured at the lowest excitation energy to-date using the CUBE fission spectrometer at The Australian National University. A new fitting procedure was developed to fit the high-statistics two-dimensional mass-kinetic energy distribution without external constraints.The fission of $^{178}$Pt can best be described by three fission modes: one mass-symmetric and two mass-asymmetric. Comparisons to previous analyses highlight the necessity of fitting the two-dimensional mass-kinetic energy distribution, rather than fitting slices of individual one-dimensional projections of the full distribution. Systematic studies of high-statistics measurements, combined with a rigorous statistical analysis offer the best chance to determine the shell effects responsible for multi-modal mass-asymmetric fission in this region of the nuclide chart.

Published
2023

11. Superdeformation in the Bismuth Nuclei

Author

Clark, R.M., Bouneau, S., Azaiez, F., Asztalos, S., Becker, J.A., Cederwall, B., Deleplanque, M.A., Diamond, R.M., Duprat, J., Fallon, P., Farris, L.P., Hughes, J.R., Kelly, W.H., Lee, I.Y., Macchiavelli, A.O., Porquet, M.G., Sharpey-Schafer, J.F., Stephens, F.S., Stoyer, M.A., Vo, D.T., Wilson, A.N., and Henry, E.A.

Published
1994

12. The Low-Spin Termination of the Superdeformed Band in {sup 135}Nd

Author

Deleplanque, M.A., Frauendorf, S., Cleark, R.M., Diamond, R.M., Stephens, F.S., Becker, J.A., Brinkman, M.J., Cederwall, B., Fallon, P., Farris, L.P., Henry, E.A., Hubel, H., Hughes, J.R., Korten, W., Lee, I.Y., Macchiavelli, A.O., Stoyer, M.A., Willsau, P., Draper, J.E., Duyar, C., and Rubel, E.

Published
1994

13. Properties of Superdeformed Bands in 153Dy

Author

Cederwall, B., Hackman, G., Galindo-Uribarri, A., Becker, J.A., Brinkman, M.J., Deleplanque, M.A., Diamond, R.M., Draper, J.E., Duyar, C., Fallon, P., Farris, L.P., Henry, E.A., Hughes, J.R., Lee, I.Y., Macchiavelli, A.O., Mullins, S.M., Radford, D.C., Rubel, E., Stephens, F.S., Stoyer, M.A., and Waddington, J.C.

Published
1994

14. A Pair of 'Identical' Superdeformed Bands in 136ND

Author

Clark, R.M., Deleplanque, M.A., Becker, J.A., Brinkman, M.J., Cederwall, B., Diamond, R.M., Draper, J.E., Duyer, C., Fallon, P., Farris, L.P., Henry, E.A., Hubel, H., Hughes, J.R., Korten, W., Lee, I.Y., Macchiavelli, A.O., Rubel, E., Stephens, F.S., Stoyer, M.A., and Willsau, P.

Published
1994

15. New Features of Superdeformed Bands in {sup 194}Hg

Author

Cederwall, B., Janssens, R.V.F., Brinkman, M.J., Lee, I.Y., Ahmad, I., Becker, J.A., Carpenter, M.P., Crowell, B., Deleplanque, M.A., Diamond, R.M., Draper, J.E., Duyar, C., Fallon, P., Farris, L.P., Henry, E.A., Henry, R.G., Hughes, J.R., Khoo, T.L., Lauritzen, T., Macchiavelli, A.O., Rubel, E., Stephens, F.S., Stoyer, M.A., Satula, W., Wiedenhoever, I., and Wyss, R.

Published
1994

16. Elastic Scattering and Reaction Cross-section of 8Li on 209Bi

Author

Sengupta C., Cook K.J., Simpson E.C., Dasgupta M., Hinde D.J., Banerjee K., Bezzina L.T., and Stoyer M.A.

Subjects
Physics, QC1-999
Abstract

Nuclear physics in the 21st century is driven by a quest to understand the properties of ever more exotic nuclear systems. Unusual structural phenom- ena are observed to arise in light weakly bound nuclei such as 8Li. 8Li has a cluster structure core of 7Li surrounded by a loosely bound neutron which is observed to influence reaction mechanisms near the fusion barrier. Elastic scat- tering provides a vital step towards understanding more complicated reaction mechanisms. In this work, elastic scattering was measured for 8Li + 2°9Bi at energies 2% to 34% above the barrier, allowing extraction of reaction cross- sections. The systematics of the reaction cross-sections of 8Li compared to neighbouring nuclei 6,7,9,11Li are discussed.

Published
2020
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21. Pion Correlations in Relativistic Heavy Ion Collisions for Three Symmetric Systems

Author

Chacon, A.D., Bistirlich, J.A., Bossingham, R.R., Bossy, H., Bowman, H.R., Clawson, C.W., Crowe, K.M., Humanic, T.J., Justice, M., Kammel, P., Kurck, J.M., Ljungfelt, S., Meyer, C.A., Betitjean, C., Rasmussen, J.O., Stoyer, M.A., Hashimoto, O., McHarris, Wm.C., Sullivan, J.P., Wolf, K.L., and Zajc, W.A.

Published
1991

24. Prompt Fission Gamma-ray Studies at DANCE

Author

Jandel, M., Rusev, G., Bond, E.M., Bredeweg, T.A., Chadwick, M.B., Couture, A., Fowler, M.M., Haight, R.C., Kawano, T., Keksis, A.L., Mosby, S.M., O’Donnell, J.M., Rundberg, R.S., Stetcu, I., Talou, P., Ullmann, J.L., Vieira, D.J., Wilhelmy, J.B., Stoyer, M.A., Haslett, R.J., Henderson, R.A., Becker, J.A., and Wu, C.Y.

Published
2014
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27. Discovery of elements 113 - 118

Author

Utyonkov, V.K., primary, Oganessian, Yu.Ts., additional, Dmitriev, S.N., additional, Itkis, M.G., additional, Moody, K.J., additional, Stoyer, M.A., additional, Shaughnessy, D.A., additional, Roberto, J.B., additional, Rykaczewski, K.P., additional, and Hamilton, J.H., additional

Published
2017
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32. New approach to precisely measure γ-ray intensities for long-lived fission products, with results for the decay of 95Zr

Author

Kolos, K., primary, Hennessy, A.M., additional, Scielzo, N.D., additional, Iacob, V.E., additional, Hardy, J.C., additional, Stoyer, M.A., additional, Tonchev, A.P., additional, Ong, W.-J., additional, Burkey, M.T., additional, Champine, B., additional, Clark, J.A., additional, Copp, P., additional, Gallant, A., additional, Norman, E.B., additional, Orford, R., additional, Park, H.I., additional, Rohrer, J., additional, Santiago-Gonzalez, D., additional, Savard, G., additional, Shaka, A.J., additional, Wang, B.S., additional, and Zhu, S., additional

Published
2021
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36. Synthesis of superheavy nuclei in the reactions of 244Pu and 248Cm with 48Ca

Author

Oganessian, Yu.Ts., Utyonkov, V.K., Lobanov, Yu.V., Abdullin, F.Sh., Polyakov, A.N., Shirokovsky, I.V., Tsyganov, Yu.S., Gulbekian, G.G., Bogomolov, S.L., Gikal, B.N., Mezentsev, A.N., Iliev, S., Subbotin, V.G., Sukhov, A.M., Ivanov, O.V., Buklanov, G.V., Subotic, K., Voinov, A.A., Itkis, M.G., Moody, K.J., Wild, J.F., Stoyer, N.J., Stoyer, M.A., Lougheed, R.W., and Laue, C.A.

Published
2002
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37. Ceramic Plutonium Target Development for the MASHA Separator for the Synthesis of Element 114

Author

Shaughnessy, D.A., primary, Wilk, P.A., additional, Moody, K.J., additional, Kenneally, J.M., additional, Wild, J.F., additional, Stoyer, M.A., additional, Stoyer, N.J., additional, Patin, J.B., additional, Landrum, J.H., additional, Lougheed, R.W., additional, Oganessian, Yu.Ts., additional, Yeremin, A.V., additional, Dmitriev, S.N., additional, Hartmann, T., additional, and Czerwinski, K.R., additional

Published
2006
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41. New insights into neutron rich nuclei from fission

Author

Hamilton, J.H., Zhu, S.J., Ramayya, A.V., Gore, P.M., Rasmussen, J.O., Jones, E.F., Hwang, J.K., Xu, R.Q., Yang, L.Y., Li, K., Jiang, Z., Zhang, Z., Ziao, S.D., Zhang, X.Q., Kormicki, J., Luo, Y.X., Chaturvedi, L., Ma, W.C., Cole, J.D., Drigert, M.W., Lee, I.Y., Fallon, P., Stoyer, M.A., Ginter, T.N., Ter-Akopian, G.M., Daniel, A.V., Oganessian, Yu.Ts., Donangelo, R., Dimitrov, V., and Frauendorf, S.

Published
2004
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42. Heavy element research at Dubna

Author

Oganessian, Yu.Ts., Utyonkov, V.K., Lobanov, Yu.V., Abdullin, F.Sh., Polyakov, A.N., Shirokovsky, I.V., Tsyganov, Yu.S., Gulbekian, G.G., Bogomolov, S.L., Gikal, B.N., Mezentsev, A.N., Iliev, S., Subbotin, V.G., Sukhov, A.M., Voinov, A.A., Buklanov, G.V., Subotic, K., Zagrebaev, V.I., Itkis, M.G., Patin, J.B., Moody, K.J., Wild, J.F., Stoyer, M.A., Stoyer, N.J., Shaughnessy, D.A., Kenneally, J.M., and Lougheed, R.W.

Published
2004
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43. Erratum to “New insights into the nuclear structure in neutron-rich 112,114,115,116,117,118Pd” [Nucl. Phys. A 919 (2013) 67–98]

Author

Luo, Y.X., primary, Rasmussen, J.O., additional, Hamilton, J.H., additional, Ramayya, A.V., additional, Frauendorf, S., additional, Hwang, J.K., additional, Stone, N.J., additional, Zhu, S.J., additional, Brewer, N.T., additional, Wang, E.H., additional, Lee, I.Y., additional, Liu, S.H., additional, Ter-Akopian, G.M., additional, Daniel, A.V., additional, Oganessian, Yu.Ts., additional, Stoyer, M.A., additional, Donangelo, R., additional, Ma, W.C., additional, Cole, J.D., additional, Shi, Y., additional, and Xu, F.R., additional

Published
2019
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44. Observation of new neutron-deficient isotopes with Z≥92 in multinucleon transfer reactions

Author

Devaraja, H.M., Heinz, S., Beliuskina, O., Comas, V., Hofmann, S., Hornung, C., Münzenberg, G., Nishio, K., Ackermann, D., Gambhir, Y.K., Gupta, M., Henderson, R.A., Heßberger, F.P., Khuyagbaatar, J., Kindler, B., Lommel, B., Moody, K.J., Maurer, J., Mann, R., Popeko, A.G., Shaughnessy, D.A., Stoyer, M.A., and Yeremin, A.V.

Subjects
Nuclear and High Energy Physics
Published
2015
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46. Energy Evolution of the Fission-Product Yields from Neutron-Induced Fission of 235U, 238U, and 239Pu: An Unexpected Observation

Author

Tonchev, A.P., primary, Stoyer, M.A., additional, Becker, J.A., additional, Macri, R., additional, Ryan, C., additional, Sheets, S.A., additional, Gooden, M.E., additional, Arnold, C.W., additional, Bond, E., additional, Bredeweg, T., additional, Fowler, M.M., additional, Rusev, G., additional, Vieira, D.J., additional, Wilhelmy, J.B., additional, Tornow, W., additional, Howell, C.R., additional, Bhatia, C., additional, Bhike, M., additional, Krishichayan, F., additional, Kelley, J.H., additional, Fallin, B., additional, and Finch, S.W., additional

Published
2017
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47. Triaxiality in Neutron-Rich Nuclei with A ˜ 100-126, Z Beyond and Below Ru (Z=44)

Author

Luo, Y.X., primary, Hamilton, J.H., additional, Rasmussen, J.O., additional, Ramayya, A.V., additional, Frauendorf, S., additional, Wang, E., additional, Hwang, J.K., additional, Wang, J.G., additional, Li, H.J., additional, Yeoh, E.Y., additional, Zhu, S.J., additional, Liu, Y.X., additional, Jiao, C.F., additional, Liang, W.Y., additional, Shi, Yue, additional, Xu, F.R., additional, Sun, Y., additional, Liu, S.H., additional, Brewer, N.T., additional, Lee, I.Y., additional, Ter-Akopian, G.M., additional, Daniel, A.V., additional, Oganessian, Yu., additional, Stoyer, M.A., additional, Donangelo, R., additional, and Ma, W.C., additional

Published
2017
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48. Narrowing of the neutron sd–pf shell gap in 29Na

Author

Hurst, A.M., Wu, C.Y., Becker, J.A., Stoyer, M.A., Pearson, C.J., Hackman, G., Schumaker, M.A., Svensson, C.E., Austin, R.A.E., Ball, G.C., Bandyopadhyay, D., Barton, C.J., Boston, A.J., Boston, H.C., Churchman, R., Cline, D., Colosimo, S.J., Cross, D.S., Demand, G., Djongolov, M., Drake, T.E., Garrett, P.E., Gray-Jones, C., Green, K.L., Grint, A.N., Hayes, A.B., Leach, K.G., Kulp, W.D., Lee, G., Lloyd, S., Maharaj, R., Martin, J.-P., Millar, B.A., Mythili, S., Nelson, L., Nolan, P.J., Oxley, D.C., Padilla-Rodal, E., Phillips, A.A., Porter-Peden, M., Rigby, S.V., Sarazin, F., Sumithrarachchi, C.S., Triambak, S., Walker, P.M., Williams, S.J., Wong, J., and Wood, J.L.

Subjects
Nuclear and High Energy Physics
Published
2009
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