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136 results on '"Stephens FS"'

1. Recent results from gammasphere

Author

Lee, IY, Clark, RM, Ward, D, Cromaz, M, Deleplanque, MA, Diamond, RM, Fallon, P, Görgen, A, Lane, GJ, Macchiavelli, AO, Stephens, FS, Svensson, CE, and Vetter, K

Subjects
Nuclear & Particles Physics, Mathematical Sciences, Physical Sciences
Abstract

Three examples of recent nuclear structure studies using Gammasphere are discussed in this paper. (1) A rotational band has been identified in 108Cd. Its moment of inertia and quadrupole moment indicate that this band has a shape with an axis ratio larger than 1.8:1. (2) Possible "Jacobi" shape transitions at high spin were investigated from studies of the continuum gamma rays on a number of nuclei. (3) Population of high-spin states in neutron-rich nuclei were studied in target fragmentation reactions. States with spin up to 6-12 were observed in a wide range of nuclei.

Published
2001

2. Fast rotation of the N = Z nucleus 36Ar

Author

Svensson, OE, Macchiavelli, AO, Juodagalvis, A, Poves, A, Ragnarsson, I, Åberg, S, Appelee, DE, Austin, RAE, Baktash, C, Ball, GG, Caurier, E, Clark, RM, Cromaz, M, Deleplanque, MA, Diamond, RM, Fallon, P, Furlotti, M, Galindo-Uribarri, A, Janssens, RVF, Lane, GJ, Lee, IY, Lipoglavsek, M, Nowacki, F, Paul, SD, Radford, DC, Sarantites, DG, Seweryniak, D, Stephens, FS, Tomov, V, Vetter, K, Ward, D, and Yu, CH

Subjects
nucl-th, Nuclear & Particles Physics, Mathematical Sciences, Physical Sciences
Abstract

A highly-deformed rotational band has been identified in the N = Z nucleus 36Ar. At high spin the band is observed to its presumed termination at Iπ = 16+, while at low spin it has been firmly linked to previously known states in 36Ar. Spins, parities, and absolute excitation energies have thus been determined throughout the band. Lifetime measurements establish a large low-spin quadrupole deformation (β2 = 0.46 ±0.03) and indicate a decreasing collectivity as the band termination is approached. With effectively complete spectroscopic information and a valence space large enough for significant collectivity to develop, yet small enough to be meaningfully approached from the shell model perspective, this rotational band in 36Ar provides many exciting opportunities to test and compare complementary models of collective motion in nuclei.

Published
2001

3. A New Measurement of the Partial 0+->0+ Half Life of 10C with GAMMASPHERE

Author

Fujikawa, BK, Asztalos, SJ, Clark, RM, Deleplanque-Stephens, M-A, Fallon, P, Freedman, SJ, Lee, I-Y, Lising, LJ, Macchiavelli, AO, MacLeod, RW, Reich, JC, Rowe, MA, Shang, S-Q, Stephens, FS, Wasserman, EG, and Greene, JP

Subjects
nucl-ex
Abstract

We report on a new measurement of the strength of the superallowed 0+->0+transition in the beta-decay of 10C: 10C(0+,g.s.)->10B(0+,1.74MeV)+e+nu. Theexperiment was done at the LBNL 88-inch cyclotron using forty seven GAMMASPHEREgermanium detectors. Precise knowledge of this branching ratio is necessary tocompute the superallowed Fermi ft, which gives the weak vector couplingconstant and the u to d element of the Cabibbo-Kobayashi- Maskawa quark mixingmatrix.

Published
1998

4. Superdeformation in $^{198}$Po

Author

McNabb, DP, Baldsiefen, G, Bernstein, LA, Cizewski, JA, Jin, H-Q, Younes, W, Becker, JA, Farris, LP, Henry, EA, Hughes, JR, Lee, CS, Asztalos, SJ, Cederwall, B, Clark, RM, Deleplanque, MA, Diamond, RM, Fallon, P, Lee, IY, Macchiavelli, AO, and Stephens, FS

Subjects
nucl-ex
Abstract

The $^{174}$Yb($^{29}$Si,5n) reaction at 148 MeV with thin targets was usedto populate high-angular momentum states in $^{198}$Po. Resulting $\gamma$ rayswere observed with Gammasphere. A weakly-populated superdeformed band of 10$\gamma$-ray transitions was found and has been assigned to $^{198}$Po. This isthe first observation of a SD band in the $A \approx 190$ region in a nucleuswith $Z > 83$. The ${\cal J}^{(2)}$ of the new band is very similar to those ofthe yrast SD bands in $^{194}$Hg and $^{196}$Pb. The intensity profile suggeststhat this band is populated through states close to where the SD band crossesthe yrast line and the angular momentum at which the fission process dominates.

Published
1995

5. Onset of collectivity in neutron deficient 196,198Po.

Author

Bernstein, LA, Cizewski, JA, Jin, H, Younes, W, Henry, RG, Farris, LP, Charos, A, Carpenter, MP, Janssens, RV, Khoo, TL, Lauritsen, T, Bearden, IG, Ye, D, Becker, JA, Henry, EA, Brinkman, MJ, Hughes, JR, Kuhnert, A, Wang, TF, Stoyer, MA, Diamond, RM, Stephens, FS, Deleplanque, MA, Macchiavelli, AO, Lee, IY, Cederwall, B, Oliveira, JR, Burde, J, Fallon, P, Duyar, C, Draper, JE, Rubel, E, and Vo, DT

Subjects
nucl-ex, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Nuclear & Particles Physics
Abstract

We have studied via in-beam -ray spectroscopy Po196 and Po198, which are the first neutron-deficient Po isotopes to exhibit a collective low-lying structure. The ratios of yrast state energies and the E2 branching ratios of transitions from non-yrast to yrast states are indicative of a low-lying vibrational structure. The onset of collective motion in these isotopes can be attributed to the opening of the neutron i13/2 orbital at N112 and the resulting large overlap between the two valence protons in the h9/2 orbital and the valence neutrons in the i13/2 orbital. © 1995 The American Physical Society.

Published
1995

6. Superdeformation in $^{198}$Po

Author

McNabb, DP, Baldsiefen, G, Bernstein, LA, Cizewski, JA, Jin, H-Q, Younes, W, Becker, JA, Farris, LP, Henry, EA, Hughes, JR, Lee, CS, Asztalos, SJ, Cederwall, B, Clark, RM, Deleplanque, MA, Diamond, RM, Fallon, P, Lee, IY, Macchiavelli, AO, and Stephens, FS

Subjects
Nuclear Theory, Nuclear Experiment, nucl-ex
Abstract

The $^{174}$Yb($^{29}$Si,5n) reaction at 148 MeV with thin targets was used to populate high-angular momentum states in $^{198}$Po. Resulting $\gamma$ rays were observed with Gammasphere. A weakly-populated superdeformed band of 10 $\gamma$-ray transitions was found and has been assigned to $^{198}$Po. This is the first observation of a SD band in the $A \approx 190$ region in a nucleus with $Z > 83$. The ${\cal J}^{(2)}$ of the new band is very similar to those of the yrast SD bands in $^{194}$Hg and $^{196}$Pb. The intensity profile suggests that this band is populated through states close to where the SD band crosses the yrast line and the angular momentum at which the fission process dominates.

Published
2018
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7. Fast rotation of the N = Z nucleus 36Ar

Author

Svensson, CE, Svensson, CE, Macchiavelli, AO, Juodagalvis, A, Poves, A, Ragnarsson, I, Åberg, S, Appelbe, DE, Austin, RAE, Baktash, C, Ball, GC, Carpenter, MP, Caurier, E, Clark, RM, Cromaz, M, Deleplanque, MA, Diamond, RM, Fallon, P, Furlotti, M, Galindo-Uribarri, A, Janssens, RVF, Lane, GJ, Lee, IY, Lipoglavsek, M, Nowacki, F, Paul, SD, Radford, DC, Sarantites, DG, Seweryniak, D, Stephens, FS, Tomov, V, Vetter, K, Ward, D, Yu, CH, Svensson, CE, Svensson, CE, Macchiavelli, AO, Juodagalvis, A, Poves, A, Ragnarsson, I, Åberg, S, Appelbe, DE, Austin, RAE, Baktash, C, Ball, GC, Carpenter, MP, Caurier, E, Clark, RM, Cromaz, M, Deleplanque, MA, Diamond, RM, Fallon, P, Furlotti, M, Galindo-Uribarri, A, Janssens, RVF, Lane, GJ, Lee, IY, Lipoglavsek, M, Nowacki, F, Paul, SD, Radford, DC, Sarantites, DG, Seweryniak, D, Stephens, FS, Tomov, V, Vetter, K, Ward, D, and Yu, CH

Published
2001

8. ROTATIONAL BANDS IN PT-181

Author

DEVOIGT, MJA, KACZAROWSKI, R, RIEZEBOS, HJ, NOORMAN, RF, BACELAR, JC, DELEPLANQUE, MA, DIAMOND, RM, STEPHENS, FS, and KVI - Center for Advanced Radiation Technology

Published
1990

9. COLLECTIVE AND QUASI-PARTICLE EXCITATIONS IN PT-180

Author

DEVOIGT, MJA, KACZAROWSKI, R, RIEZEBOS, HJ, NOORMAN, RF, BACELAR, JC, DELEPLANQUE, MA, DIAMOND, RM, STEPHENS, FS, SAUVAGE, J, ROUSSIERE, B, and KVI - Center for Advanced Radiation Technology

Published
1990

10. ONSET OF COLLECTIVITY IN NEUTRON-DEFICIENT PO-196,PO-198

Author

BERNSTEIN, LA, CIZEWSKI, JA, JIN, HQ, YOUNES, W, HENRY, RG, FARRIS, LP, CHAROS, A, CARPENTER, MP, JANSSENS, RVF, KHOO, TL, LAURITSEN, T, BEARDEN, IG, YE, D, BECKER, JA, HENRY, EA, BRINKMAN, MJ, HUGHES, JR, KUHNERT, A, WANG, TF, STOYER, MA, DIAMOND, RM, STEPHENS, FS, DELEPLANQUE, MA, MACCHIAVELLI, AO, LEE, IY, Cederwall, Bo, OLIVEIRA, JRB, BURDE, J, FALLON, P, DUYAR, C, DRAPER, JE, RUBEL, E, VO, DT, BERNSTEIN, LA, CIZEWSKI, JA, JIN, HQ, YOUNES, W, HENRY, RG, FARRIS, LP, CHAROS, A, CARPENTER, MP, JANSSENS, RVF, KHOO, TL, LAURITSEN, T, BEARDEN, IG, YE, D, BECKER, JA, HENRY, EA, BRINKMAN, MJ, HUGHES, JR, KUHNERT, A, WANG, TF, STOYER, MA, DIAMOND, RM, STEPHENS, FS, DELEPLANQUE, MA, MACCHIAVELLI, AO, LEE, IY, Cederwall, Bo, OLIVEIRA, JRB, BURDE, J, FALLON, P, DUYAR, C, DRAPER, JE, RUBEL, E, and VO, DT

Abstract

We have studied via in-beam gamma-ray spectroscopy Po-196 and Po-198, which are the first neutron-deficient Po isotopes to exhibit a collective low-lying structure. The ratios of yrast state energies and the E2 branching ratios of transitions from non-yrast to yrast states are indicative of a low-lying vibrational structure. The onset of collective motion in these isotopes can be attributed to the opening of the neutron i(13/2) orbital at N approximate to 112 and the resulting large overlap between the two valence protons in the h(9/2) orbital and the valence neutrons in the i(13/2) orbital., NR 2015

Published
1995
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11. SUPERDEFORMATION IN PB-193 AND THE EFFECTS OF THE N=7 INTRUDER ORBITAL

Author

HUGHES, JR, BECKER, JA, BERNSTEIN, LA, BRINKMAN, MJ, FARRIS, LP, HENRY, EA, HOFF, RW, STOYER, MA, VO, DT, ASZTALOS, S, Cederwall, Bo, CLARK, RM, DELEPLANQUE, MA, DIAMOND, RM, FALLON, P, LEE, IY, MACCHIAVELLI, AO, STEPHENS, FS, HUGHES, JR, BECKER, JA, BERNSTEIN, LA, BRINKMAN, MJ, FARRIS, LP, HENRY, EA, HOFF, RW, STOYER, MA, VO, DT, ASZTALOS, S, Cederwall, Bo, CLARK, RM, DELEPLANQUE, MA, DIAMOND, RM, FALLON, P, LEE, IY, MACCHIAVELLI, AO, and STEPHENS, FS

Abstract

NR 2015

Published
1995
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12. IDENTIFICATION OF THE UNFAVORED N=7 SUPERDEFORMED BAND IN HG-191

Author

CARPENTER, MP, JANSSENS, RVF, Cederwall, Bo, CROWELL, B, AHMAD, I, BECKER, JA, BRINKMAN, MJ, DELEPLANQUE, MA, DIAMOND, RM, FALLON, P, FARRIS, LP, GARG, U, GASSMANN, D, HENRY, EA, HENRY, RG, HUGHES, JR, KHOO, TL, LAURITSEN, T, LEE, IY, MACHIAVELLI, AO, MOORE, EF, NISIUS, D, STEPHENS, FS, CARPENTER, MP, JANSSENS, RVF, Cederwall, Bo, CROWELL, B, AHMAD, I, BECKER, JA, BRINKMAN, MJ, DELEPLANQUE, MA, DIAMOND, RM, FALLON, P, FARRIS, LP, GARG, U, GASSMANN, D, HENRY, EA, HENRY, RG, HUGHES, JR, KHOO, TL, LAURITSEN, T, LEE, IY, MACHIAVELLI, AO, MOORE, EF, NISIUS, D, and STEPHENS, FS

Abstract

NR 2015

Published
1995
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13. PROTON AND NEUTRON EXCITATIONS IN SUPERDEFORMED TB-150

Author

FALLON, P, BEAUSANG, CW, ASZTALOS, S, NISIUS, D, JANSSENS, RVF, BERGSTROM, M, CARPENTER, M, Cederwall, Bo, CLARKE, S, CROWELL, B, DELEPLANQUE, MA, DIAMOND, RM, HENRY, RG, KHOO, TL, LAURITSEN, T, LEE, IY, MACCHIAVELLI, AO, STEPHENS, FS, TWIN, PJ, FALLON, P, BEAUSANG, CW, ASZTALOS, S, NISIUS, D, JANSSENS, RVF, BERGSTROM, M, CARPENTER, M, Cederwall, Bo, CLARKE, S, CROWELL, B, DELEPLANQUE, MA, DIAMOND, RM, HENRY, RG, KHOO, TL, LAURITSEN, T, LEE, IY, MACCHIAVELLI, AO, STEPHENS, FS, and TWIN, PJ

Abstract

Two new superdeformed (SD) bands have been observed in Tb-150 using the reaction P-31 + Sn-124 and the GAMMASPHERE detector array. These new bands are interpreted as being excited SD configurations involving a proton and a neutron particle-hole excitation, respectively. The configurations are discussed in terms of the occupancy of high-N intruder orbitals. These data are used to provide information on (i) the contribution to the dynamic moments of inertia due to the occupation of specific orbitals, (ii) the deformation driving effects of the particle-hole states, and (iii) the consequences of these effects on pairing and band crossings., NR 2015

Published
1995
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14. LOW-SPIN TERMINATION OF THE SUPERDEFORMED BAND IN ND-135

Author

DELEPLANQUE, MA, FRAUENDORF, S, CLARK, RM, DIAMOND, RM, STEPHENS, FS, BECKER, JA, BRINKMAN, MJ, Cederwall, Bo, FALLON, P, FARRIS, LP, HENRY, EA, HUBEL, H, HUGHES, JR, KORTEN, W, LEE, IY, MACCHIAVELLI, AO, STOYER, MA, WILLSAU, P, DRAPER, JE, DUYAR, C, RUBEL, E, DELEPLANQUE, MA, FRAUENDORF, S, CLARK, RM, DIAMOND, RM, STEPHENS, FS, BECKER, JA, BRINKMAN, MJ, Cederwall, Bo, FALLON, P, FARRIS, LP, HENRY, EA, HUBEL, H, HUGHES, JR, KORTEN, W, LEE, IY, MACCHIAVELLI, AO, STOYER, MA, WILLSAU, P, DRAPER, JE, DUYAR, C, and RUBEL, E

Abstract

The decay of the superdeformed (SD) band in Nd-135 was studied with the early implementation of gamma-sphere. The results suggest that the SD band ''terminates'' at spin 25/2. This termination is explained by a change of the SD minimum toward a triaxial lower deformation. Ultimate cranker calculations with the i(13/2) orbital occupied relate this change to a shift of a proton and neutron pair out of deformation-driving Nilsson orbitals. This is a completely new and unexpected mechanism for the decay of SD bands., NR 2015

Published
1995
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15. NEUTRON BLOCKING AND DELAYED PROTON PAIR ALIGNMENT IN SUPERDEFORMED PB-195

Author

FARRIS, LP, HENRY, EA, BECKER, JA, BRINKMAN, MJ, Cederwall, Bo, CIZEWSKI, JA, DELEPLANQUE, MA, DIAMOND, RM, DRAPER, JE, DUYAR, C, FALLON, P, HUGHES, JR, KELLY, WH, LEE, IY, MACCHIAVELLI, AO, RUBEL, EC, STEPHENS, FS, STOYER, MA, VO, DT, FARRIS, LP, HENRY, EA, BECKER, JA, BRINKMAN, MJ, Cederwall, Bo, CIZEWSKI, JA, DELEPLANQUE, MA, DIAMOND, RM, DRAPER, JE, DUYAR, C, FALLON, P, HUGHES, JR, KELLY, WH, LEE, IY, MACCHIAVELLI, AO, RUBEL, EC, STEPHENS, FS, STOYER, MA, and VO, DT

Abstract

NR 2015

Published
1995
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16. QUASI-PARTICLE EXCITATIONS IN SUPERDEFORMED HG-192

Author

FALLON, P, LAURITSEN, T, AHMAD, I, CARPENTER, MP, Cederwall, Bo, CLARK, RM, CROWELL, B, DELEPLANQUE, MA, DIAMOND, RM, GALL, B, HANNACHI, F, HENRY, RG, JANSSENS, RVF, KHOO, TL, KORICHI, A, LEE, IY, MACCHIAVELLI, AO, SCHUCK, C, STEPHENS, FS, FALLON, P, LAURITSEN, T, AHMAD, I, CARPENTER, MP, Cederwall, Bo, CLARK, RM, CROWELL, B, DELEPLANQUE, MA, DIAMOND, RM, GALL, B, HANNACHI, F, HENRY, RG, JANSSENS, RVF, KHOO, TL, KORICHI, A, LEE, IY, MACCHIAVELLI, AO, SCHUCK, C, and STEPHENS, FS

Abstract

NR 2015

Published
1995
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17. SUPERDEFORMATION IN THE BISMUTH NUCLEI

Author

CLARK, RM, BOUNEAU, S, AZAIEZ, F, ASZTALOS, S, BECKER, JA, Cederwall, Bo, DELEPLANQUE, MA, DIAMOND, RM, DUPRAT, J, FALLON, P, FARRIS, LP, HENRY, EA, HUGHES, JR, KELLY, WH, LEE, IY, MACCHIAVELLI, AO, PORQUET, MG, SHARPEYSCHAFER, JF, STEPHENS, FS, STOYER, MA, VO, DT, WILSON, AN, CLARK, RM, BOUNEAU, S, AZAIEZ, F, ASZTALOS, S, BECKER, JA, Cederwall, Bo, DELEPLANQUE, MA, DIAMOND, RM, DUPRAT, J, FALLON, P, FARRIS, LP, HENRY, EA, HUGHES, JR, KELLY, WH, LEE, IY, MACCHIAVELLI, AO, PORQUET, MG, SHARPEYSCHAFER, JF, STEPHENS, FS, STOYER, MA, VO, DT, and WILSON, AN

Abstract

NR 2015

Published
1995
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18. SUPERDEFORMATION IN ER-154

Author

BERNSTEIN, LA, HUGHES, JR, BECKER, JA, FARRIS, LP, HENRY, EA, ASZTALOS, SJ, Cederwall, Bo, CLARK, RM, DELEPLANQUE, MA, DIAMOND, RM, FALLON, P, LEE, IY, MACCHIAVELLI, AO, STEPHENS, FS, CIZEWSKI, JA, YOUNES, W, BERNSTEIN, LA, HUGHES, JR, BECKER, JA, FARRIS, LP, HENRY, EA, ASZTALOS, SJ, Cederwall, Bo, CLARK, RM, DELEPLANQUE, MA, DIAMOND, RM, FALLON, P, LEE, IY, MACCHIAVELLI, AO, STEPHENS, FS, CIZEWSKI, JA, and YOUNES, W

Abstract

A superdeformed (SD) band consisting of 13 gamma-ray transitions has been observed in Er-154, an isotone of Dy-152(66). The experiment was performed using the Sn-118(Ar-40,4n) reaction at E(Ar-40)=185 MeV and the early implementation of GAMMASPHERE. This is an observation of a SD band in the A approximate to 150 region with a proton number greater than 66. The J((2)) moment of inertia of the band is constant above ($) over bar h omega=0.45 MeV and shows a sharp rise below this value suggesting a paired band crossing. These results suggest that total Routhian surface calculations fail to accurately predict the deformation of the band., NR 2015

Published
1995
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19. C-4 SYMMETRY EFFECTS IN NUCLEAR ROTATIONAL MOTION

Author

MACCHIAVELLI, AO, CEDERWALL, BO, CLARK, RM, DELEPLANQUE, MA, DIAMOND, RM, FALLEN, P, LEE, IY, STEPHENS, FS, ASZTALOS, S, MACCHIAVELLI, AO, CEDERWALL, BO, CLARK, RM, DELEPLANQUE, MA, DIAMOND, RM, FALLEN, P, LEE, IY, STEPHENS, FS, and ASZTALOS, S

Abstract

NR 20151210

Published
1995
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20. PROPERTIES OF SUPERDEFORMED BANDS IN DY-153

Author

Cederwall, Bo, HACKMAN, G, GALINDOURIBARRI, A, RADFORD, DC, BECKER, JA, BRINKMAN, MJ, DELEPLANQUE, MA, DIAMOND, RM, DRAPER, JE, DUYAR, C, FALLON, P, FARRIS, LP, HENRY, EA, HUGHES, JR, LEE, IY, MACCHIAVELLI, AO, MULLINS, SM, RUBEL, E, STEPHENS, FS, STOYER, MA, WADDINGTON, JC, Cederwall, Bo, HACKMAN, G, GALINDOURIBARRI, A, RADFORD, DC, BECKER, JA, BRINKMAN, MJ, DELEPLANQUE, MA, DIAMOND, RM, DRAPER, JE, DUYAR, C, FALLON, P, FARRIS, LP, HENRY, EA, HUGHES, JR, LEE, IY, MACCHIAVELLI, AO, MULLINS, SM, RUBEL, E, STEPHENS, FS, STOYER, MA, and WADDINGTON, JC

Abstract

Two new superdeformed (SD) bands in Dy-153, in addition to the three previously observed, have been studied with the GAMMASPHERE detector array. Assignments to single-neutron orbits in the SD potential are made based on the band properties. Evidence for a band interaction at very high spins, possibly involving the first N = 7 proton intruder orbital, is observed in the strongest populated SD band. Furthermore, evidence far a Delta I = 2 staggering is also found in this SD band., NR 2015

Published
1995
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21. COULOMB-EXCITATION OF SE-76,SE-80,SE-82

Author

KAVKA, AE, FAHLANDER, C, BACKLIN, A, CLINE, D, CZOSNYKA, T, DIAMOND, RM, DISDIER, D, KERNAN, WJ, KRAUS, L, LINCK, I, SCHULZ, N, SREBRNY, J, STEPHENS, FS, SVENSSON, LE, VARNESTIG, B, VOGT, EG, WU, CY, KAVKA, AE, FAHLANDER, C, BACKLIN, A, CLINE, D, CZOSNYKA, T, DIAMOND, RM, DISDIER, D, KERNAN, WJ, KRAUS, L, LINCK, I, SCHULZ, N, SREBRNY, J, STEPHENS, FS, SVENSSON, LE, VARNESTIG, B, VOGT, EG, and WU, CY

Published
1995

22. MEASUREMENT OF ULTRA-FAST GAMMA-RAY TRANSITIONS FROM HEAVY-ION COMPOUND NUCLEUS REACTIONS

Author

Cederwall, Bo, LEE, IY, ASZTALOS, S, BRINKMAN, MJ, BECKER, JA, CLARK, RM, DELEPLANQUE, MA, DIAMOND, RM, FALLON, P, FARRIS, LP, HENRY, EA, HUGHES, JR, MACCHIAVELLI, AO, STEPHENS, FS, Cederwall, Bo, LEE, IY, ASZTALOS, S, BRINKMAN, MJ, BECKER, JA, CLARK, RM, DELEPLANQUE, MA, DIAMOND, RM, FALLON, P, FARRIS, LP, HENRY, EA, HUGHES, JR, MACCHIAVELLI, AO, and STEPHENS, FS

Abstract

A method for correcting target-thickness-induced Doppler broadening in gamma-ray spectra from weakly populated, very short-lived (femtosecond) states is presented. The method is illustrated by an analysis of superdeformed transitions in Dy-152,Dy-153 for which the validity of the procedure could be verified consistently from previous lifetime measurements in Dy-152. Furthermore, estimates of the superdeformed lifetimes, previously not measured in Dy-153, are obtained., NR 2015

Published
1995
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23. A PAIR OF IDENTICAL SUPERDEFORMED BANDS IN ND-136

Author

CLARK, RM, DELEPLANQUE, MA, Cederwall, Bo, DIAMOND, RM, FALLON, P, LEE, IY, MACCHIAVELLI, AO, STEPHENS, FS, BECKER, JA, BRINKMAN, MJ, FARRIS, LP, HENRY, EA, HUGHES, JR, STOYER, MA, DRAPER, JE, DUYAR, C, RUBEL, E, HUBEL, H, KORTEN, W, WILLSAU, P, CLARK, RM, DELEPLANQUE, MA, Cederwall, Bo, DIAMOND, RM, FALLON, P, LEE, IY, MACCHIAVELLI, AO, STEPHENS, FS, BECKER, JA, BRINKMAN, MJ, FARRIS, LP, HENRY, EA, HUGHES, JR, STOYER, MA, DRAPER, JE, DUYAR, C, RUBEL, E, HUBEL, H, KORTEN, W, and WILLSAU, P

Abstract

High-spin states in Nd-136 were populated via the Mo-100(Ar-40, 4n) reaction at beam energies of 176 and 182 MeV, and resulting gamma-rays were detected using the GAMMASPHERE spectrometer. Analysis of the data has revealed the existence of an excited superdeformed (SD) band in Nd-136. Th, yrast SD band in Nd-136 has been extended by the addition of four (possibly five) transitions at high frequency. The new band displays the remarkable property of having transition energies identical (to within +/- 1 keV) to those of the half-points of the yrast SD band of Nd-136. Possible explanations in terms of cranked Woods-Saxon single-particle calculations are discussed., NR 2015

Published
1995
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24. CONFIRMATION OF THE SUPERDEFORMED BAND IN PB-192

Author

ASZTALOS, SJ, FALLON, P, CLARK, RM, BECKER, JA, BERNSTEIN, LA, Cederwall, Bo, DELEPLANQUE, MA, DIAMOND, RM, FARRIS, LP, HENRY, EA, KELLY, WH, LEE, IY, MACCHIAVELLI, AO, STEPHENS, FS, ASZTALOS, SJ, FALLON, P, CLARK, RM, BECKER, JA, BERNSTEIN, LA, Cederwall, Bo, DELEPLANQUE, MA, DIAMOND, RM, FARRIS, LP, HENRY, EA, KELLY, WH, LEE, IY, MACCHIAVELLI, AO, and STEPHENS, FS

Abstract

High-spin states in Pb-192 were populated via the reaction Yb-173(Mg-24,5n) at a beam energy of 140 MeV, and the resulting gamma-rays were deteced using GAMMA-SPHERE. A previously observed superdeformed band in Pb-192 has been confirmed., NR 2915

Published
1995
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25. IDENTICAL SUPERDEFORMED BAND IN DY-151 - FURTHER EVIDENCE FOR THE PSEUDOSPIN COUPLING SCHEME

Author

NISIUS, D, JANSSENS, RVF, FALLON, P, CROWELL, B, AHMAD, I, BEAUSANG, CW, CARPENTER, MP, CEDERWALL, BO, DALY, PJ, DELEPLANQUE, MA, DIAMOND, RM, GASSMANN, D, GRABOWSKI, ZW, HENRY, RG, KHOO, TL, LAURITSEN, T, LEE, IY, MACCHIAVELLI, AO, MAYER, RH, STEPHENS, FS, TWIN, PJ, NISIUS, D, JANSSENS, RVF, FALLON, P, CROWELL, B, AHMAD, I, BEAUSANG, CW, CARPENTER, MP, CEDERWALL, BO, DALY, PJ, DELEPLANQUE, MA, DIAMOND, RM, GASSMANN, D, GRABOWSKI, ZW, HENRY, RG, KHOO, TL, LAURITSEN, T, LEE, IY, MACCHIAVELLI, AO, MAYER, RH, STEPHENS, FS, and TWIN, PJ

Abstract

One of the four new excited superdeformed bands found in Dy-151 is characterized by transition energies that lie midway between the gamma-ray energies of the yrast superdeformed band in Dy-152. This result adds significant new information on the issue of ''identical'' bands, as it confirms predictions based on the strong coupling model and the pseudospin coupling scheme., NR 20151210

Published
1995
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26. HIGH-K BANDS IN THE YB-166 REGION

Author

OLIVEIRA, JRB, FRAUENDORF, S, DELEPLANQUE, MA, CEDERWALL, BO, DIAMOND, RM, MACCHIAVELLI, AO, STEPHENS, FS, BURDE, J, DRAPER, JE, DUYAR, C, RUBEL, E, BECKER, JA, HENRY, EA, BRINKMAN, MJ, KUHNERT, A, STOYER, MA, WANG, TF, OLIVEIRA, JRB, FRAUENDORF, S, DELEPLANQUE, MA, CEDERWALL, BO, DIAMOND, RM, MACCHIAVELLI, AO, STEPHENS, FS, BURDE, J, DRAPER, JE, DUYAR, C, RUBEL, E, BECKER, JA, HENRY, EA, BRINKMAN, MJ, KUHNERT, A, STOYER, MA, and WANG, TF

Abstract

High-K bands have been observed in the Yb-166,Yb-167,Yb-168 isotopes following the Sn-124(Ca-48,xn gamma) reaction. The nu h(11/2) bend in Yb-167 has been extended to higher spins. The high-K bands in the even-even isotopes were observed for the first time and show very high B(M1)/B(E2) ratios. Configuration assignments for the new bands are proposed. The results are interpreted within the tilted cranking model., NR 20151210

Published
1994
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27. EXCITATIONS IN DOUBLY-MAGIC SUPERDEFORMED PB-194

Author

HUGHES, JR, BECKER, JA, BRINKMAN, MJ, FARRIS, LP, HENRY, EA, HOFF, RW, STOYER, MA, Cederwall, Bo, DELEPLANQUE, MA, DIAMOND, RM, FALLON, P, LEE, IY, MACCHIAVELLI, AO, STEPHENS, FS, BERNSTEIN, LA, YOUNES, W, JIN, HQ, DRAPER, JE, DUYAR, C, RUBEL, E, KELLY, WH, VO, DT, HUGHES, JR, BECKER, JA, BRINKMAN, MJ, FARRIS, LP, HENRY, EA, HOFF, RW, STOYER, MA, Cederwall, Bo, DELEPLANQUE, MA, DIAMOND, RM, FALLON, P, LEE, IY, MACCHIAVELLI, AO, STEPHENS, FS, BERNSTEIN, LA, YOUNES, W, JIN, HQ, DRAPER, JE, DUYAR, C, RUBEL, E, KELLY, WH, and VO, DT

Abstract

A new superdeformed band with an intensity similar to 5% relative to the yrast superdeformed band has been observed in Pb-194. Evidence for a second new band corresponding to the signature partner is also presented. These bands were observed with GAMMASPHERE early implementation via the Yb-174(Mg-25, 5n) reaction at a beam energy of 130 MeV. The rotational characteristics of the new bands suggest an interpretation involving particle-hole excitations in the doubly-magic Pb-194 superdeformed core. The results are compared to neighboring nuclei and recent theoretical calculations, and possible configurations are suggested., NR 2015

Published
1994
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28. GAMMA-RAY SPECTROSCOPY USING DEEP-INELASTIC REACTIONS

Author

BECKER, JA, Cederwall, Bo, DELEPLANQUE, MA, DIAMOND, RM, FALLON, P, HUA, PF, LEE, IY, MACCHIAVELLI, AO, SALADIN, JX, SARANTITES, DG, SOBOTKA, LG, STEPHENS, FS, WOZNIAK, GJ, YU, CH, BECKER, JA, Cederwall, Bo, DELEPLANQUE, MA, DIAMOND, RM, FALLON, P, HUA, PF, LEE, IY, MACCHIAVELLI, AO, SALADIN, JX, SARANTITES, DG, SOBOTKA, LG, STEPHENS, FS, WOZNIAK, GJ, and YU, CH

Abstract

NR 2015

Published
1994

29. LIFETIME MEASUREMENT IN EXCITED AND YRAST SUPERDEFORMED BANDS IN A=190 REGION

Author

HUGHES, JR, AHMAD, I, BECKER, JA, BRINKMAN, MJ, CARPENTER, MP, Cederwall, Bo, DELEPLANQUE, MA, DIAMOND, RM, DRAPER, JE, DUYAR, C, FALLON, P, HARFENIST, S, HENRY, EA, HENRY, RG, HOFF, RW, JANSSENS, RVF, KHOO, TL, LAURITSEN, T, LEE, IY, RUBEL, E, STEPHENS, FS, STOYER, MA, HUGHES, JR, AHMAD, I, BECKER, JA, BRINKMAN, MJ, CARPENTER, MP, Cederwall, Bo, DELEPLANQUE, MA, DIAMOND, RM, DRAPER, JE, DUYAR, C, FALLON, P, HARFENIST, S, HENRY, EA, HENRY, RG, HOFF, RW, JANSSENS, RVF, KHOO, TL, LAURITSEN, T, LEE, IY, RUBEL, E, STEPHENS, FS, and STOYER, MA

Abstract

NR 2015

Published
1994

30. NEW FEATURES OF SUPERDEFORMED BANDS IN HG-194

Author

Cederwall, Bo, JANSSENS, RVF, BRINKMAN, MJ, LEE, IY, AHMAD, I, BECKER, JA, CARPENTER, MP, CROWELL, B, DELEPLANQUE, MA, DIAMOND, RM, DRAPER, JE, DUYAR, C, FALLON, P, FARRIS, LP, HENRY, EA, HENRY, RG, HUGHES, JR, KHOO, TL, LAURITSEN, T, MACCHIAVELLI, AO, RUBEL, E, STEPHENS, FS, STOYER, MA, SATULA, W, WIEDENHOEVER, I, WYSS, R, Cederwall, Bo, JANSSENS, RVF, BRINKMAN, MJ, LEE, IY, AHMAD, I, BECKER, JA, CARPENTER, MP, CROWELL, B, DELEPLANQUE, MA, DIAMOND, RM, DRAPER, JE, DUYAR, C, FALLON, P, FARRIS, LP, HENRY, EA, HENRY, RG, HUGHES, JR, KHOO, TL, LAURITSEN, T, MACCHIAVELLI, AO, RUBEL, E, STEPHENS, FS, STOYER, MA, SATULA, W, WIEDENHOEVER, I, and WYSS, R

Abstract

Two new features of superdeformed (SD) bands in the A almost-equal-to 190 region emerge from a study of Hg-194 with the Gammasphere detector array. A decrease of the dynamic moment of inertia is observed for rotational frequencies HBARomega greater-than-or-equal-to 0.4 MeV, confirming long standing expectations based on mean field calculations with pairing. Evidence for a small staggering in the SD transition energies is also observed, suggesting the presence of terms with fourfold symmetry in the SD Hamiltonian., NR 2015

Published
1994
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31. LIFETIME MEASUREMENT IN EXCITED AND YRAST SUPERDEFORMED BANDS IN HG-194

Author

HUGHES, JR, AHMAD, I, BECKER, JA, BRINKMAN, MJ, CARPENTER, MP, Cederwall, Bo, DELEPLANQUE, MA, DIAMOND, RM, DRAPER, JE, DUYAR, C, FALLON, P, HARFENIST, S, HENRY, EA, HENRY, RG, HOFF, RW, JANSSENS, RVF, KHOO, TL, LAURITSEN, T, LEE, IY, RUBEL, E, STEPHENS, FS, STOYER, MA, HUGHES, JR, AHMAD, I, BECKER, JA, BRINKMAN, MJ, CARPENTER, MP, Cederwall, Bo, DELEPLANQUE, MA, DIAMOND, RM, DRAPER, JE, DUYAR, C, FALLON, P, HARFENIST, S, HENRY, EA, HENRY, RG, HOFF, RW, JANSSENS, RVF, KHOO, TL, LAURITSEN, T, LEE, IY, RUBEL, E, STEPHENS, FS, and STOYER, MA

Abstract

Nuclear level lifetimes have been measured in two superdeformed bands in Hg-194 using the Doppler-shift attenuation method. Average transition quadrupole moments derived from the life-times of an excited and yrast superdeformed bands are Q(t) = 17.6(30) and 17.2(20) eb, respectively. The Doppler shifts of the excited band relative to the yrast band indicate a slight difference in quadrupole moments [+4(5)%], assuming similar side feeding. These results imply that the second well is stable and rigid with respect to the particle excitation responsible for this excited band., NR 2015

Published
1994
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32. LIFETIME MEASUREMENTS IN THE REGULAR DELTA-I = 1 OBLATE BAND IN PB-197

Author

HUGHES, JR, BECKER, JA, BRINKMAN, MJ, HENRY, EA, HOFF, RW, STOYER, MA, WANG, TF, Cederwall, Bo, DELEPLANQUE, MA, DIAMOND, RM, FALLON, P, LEE, IY, OLIVEIRA, JRB, STEPHENS, FS, CIZEWSKI, JA, BERNSTEIN, LA, DRAPER, JE, DUYAR, C, RUBEL, E, KELLY, WH, VO, D, HUGHES, JR, BECKER, JA, BRINKMAN, MJ, HENRY, EA, HOFF, RW, STOYER, MA, WANG, TF, Cederwall, Bo, DELEPLANQUE, MA, DIAMOND, RM, FALLON, P, LEE, IY, OLIVEIRA, JRB, STEPHENS, FS, CIZEWSKI, JA, BERNSTEIN, LA, DRAPER, JE, DUYAR, C, RUBEL, E, KELLY, WH, and VO, D

Abstract

Lifetimes of states in the regular DELTAI = 1 band in 197Pb have been measured with the Doppler-shift attenuation method. Excited states in 197Pb were populated using the Sm-154(48Ca, 5n) reaction at E(b) = 210 MeV. The target consisted of 1 mg/cm2 Sm-154 evaporated onto a 10 mg/cm2 Au backing. Discernible lineshapes for gamma rays in the energy range 300 < E(gamma) < 500 keV in the regular band were observed in a spectroscopic study with the 20 Ge-detector array, HERA. Level lifetimes were obtained from a lineshape analysis. Averaged reduced transition strengths, B(M1) approximately 1.7 W.u. and B(E2) approximately 18 W.u., are deduced and these are compared with theoretical predictions for the suggested configuration of this band., NR 2015

Published
1993
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33. NEW OBLATE BAND IN HG-196 WITH QUENCHED M1 STRENGTH

Author

Cederwall, Bo, DELEPLANQUE, MA, AZAIEZ, F, DIAMOND, RM, FALLON, P, KORTEN, W, LEE, IY, MACCHIAVELLI, AO, OLIVEIRA, JRB, STEPHENS, FS, KELLY, WH, VO, DT, BECKER, JA, BRINKMAN, MJ, HENRY, EA, HUGHES, JR, KUHNERT, A, STOYER, MA, WANG, TF, DRAPER, JE, DUYAR, C, RUBEL, E, DEBOER, J, Cederwall, Bo, DELEPLANQUE, MA, AZAIEZ, F, DIAMOND, RM, FALLON, P, KORTEN, W, LEE, IY, MACCHIAVELLI, AO, OLIVEIRA, JRB, STEPHENS, FS, KELLY, WH, VO, DT, BECKER, JA, BRINKMAN, MJ, HENRY, EA, HUGHES, JR, KUHNERT, A, STOYER, MA, WANG, TF, DRAPER, JE, DUYAR, C, RUBEL, E, and DEBOER, J

Abstract

High-spin states in the nucleUs Hg-196 were populated in the reaction (Os(Be,5n))-Os-192 at a beam energy of 65 MeV. A regular rotational-like DELTAI = 1 band has been observed up to an excitation energy of E* almost-equal-to 8.7 MeV and spin I almost-equal-to 30hBAR. This is the second observation of a band of this character in a mercury isotope. The experimental results are compared with mean field calculations and semiclassical estimates based on the Donau-Frauendorf formalism. The mercury bands show significantly lower B(M1)/B(E2) branching ratios as compared with similar bands in light lead nuclei. This difference may be more readily explained by a difference in single-particle structure rather than by large differences in deformation between the lead and mercury configurations., NR 2015

Published
1993
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34. COLLECTIVE OBLATE BANDS IN PB NUCLEI

Author

HENRY, EA, BECKER, JA, HUGHES, JR, BRINKMAN, MJ, WANG, TF, STOYER, MA, KUHNERT, A, DIAMOND, RM, STEPHENS, FS, DELEPLANQUE, MA, FALLON, P, LEE, IY, Cederwall, Bo, CIZEWSKI, JA, BERNSTEIN, LA, HENRY, EA, BECKER, JA, HUGHES, JR, BRINKMAN, MJ, WANG, TF, STOYER, MA, KUHNERT, A, DIAMOND, RM, STEPHENS, FS, DELEPLANQUE, MA, FALLON, P, LEE, IY, Cederwall, Bo, CIZEWSKI, JA, and BERNSTEIN, LA

Abstract

NR 2015

Published
1993

35. SUPERDEFORMATION IN AU-191

Author

VO, DT, KELLY, WH, WOHN, FK, HILL, JC, DELEPLANQUE, MA, DIAMOND, RM, STEPHENS, FS, OLIVEIRA, JRB, BURDE, J, MACCHIAVELLI, AO, DEBOER, J, Cederwall, Bo, LEE, IY, FALLON, P, BECKER, JA, HENRY, EA, BRINKMAN, MJ, KUHNERT, A, STOYER, MA, HUGHES, JR, DRAPER, JE, DUYAR, C, RUBEL, E, VO, DT, KELLY, WH, WOHN, FK, HILL, JC, DELEPLANQUE, MA, DIAMOND, RM, STEPHENS, FS, OLIVEIRA, JRB, BURDE, J, MACCHIAVELLI, AO, DEBOER, J, Cederwall, Bo, LEE, IY, FALLON, P, BECKER, JA, HENRY, EA, BRINKMAN, MJ, KUHNERT, A, STOYER, MA, HUGHES, JR, DRAPER, JE, DUYAR, C, and RUBEL, E

Abstract

A superdeformed band has been observed for the first time in an Au isotope. The reaction used was B-11 + W-186, demonstrating that very light ions can be used to populate superdeformed (SD) bands at high angular momentum. The band is assigned to 191Au. The gamma-ray energies are at the quarter-point energies of the 192Hg SD band, indicating that it is ''identical'' to that of 192Hg., NR 2015

Published
1993
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36. EVIDENCE FOR M1 TRANSITIONS BETWEEN SUPERDEFORMED STATES IN HG-193

Author

FALLON, P, BURDE, J, Cederwall, Bo, DELEPLANQUE, MA, DIAMOND, RM, LEE, IY, OLIVEIRA, JRB, STEPHENS, FS, BECKER, JA, BRINKMAN, MJ, HENRY, EA, KUHNERT, A, STOYER, MA, DRAPER, JE, DUYAR, C, RUBEL, E, FALLON, P, BURDE, J, Cederwall, Bo, DELEPLANQUE, MA, DIAMOND, RM, LEE, IY, OLIVEIRA, JRB, STEPHENS, FS, BECKER, JA, BRINKMAN, MJ, HENRY, EA, KUHNERT, A, STOYER, MA, DRAPER, JE, DUYAR, C, and RUBEL, E

Abstract

Two-way decay has been observed between superdeformed bands in Hg193. it is proposed the decays have M 1 multipolarity and connect signature partner bands. Candidates for the two-way gamma decays connecting superdeformed bands are observed for the first time., NR 2015

Published
1993
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37. HIGH-SPIN SPECTROSCOPY OF HF-168

Author

BECK, EM, DELEPLANQUE, MA, DIAMOND, RM, MCDONALD, RJ, STEPHENS, FS, BACELAR, JC, DRAPER, JE, and KVI - Center for Advanced Radiation Technology

Published
1987

39. Band structure of Ge-68

Author

Ward, D., Svensson, Ce, Ragnarsson, I., Baktash, C., Bentley, Ma, Cameron, Ja, Michael Patten Carpenter, Clark, Rm, Cromaz, M., Deleplanque, Ma, Devlin, M., Diamond, Rm, Fallon, P., Flibotte, S., Galindo-Uribarri, A., Haslip, Ds, Janssens, Rvf, Lampman, T., Lane, Gj, Lee, Iy, Lerma, F., Macchiavelli, Ao, Paul, Sd, Radford, D., Rudolph, D., Sarantites, Dg, Schaly, B., Seweryniak, D., Stephens, Fs, Thelen, O., Vetter, K., Waddington, Jc, Wilson, Jn, and Yu, Ch

40. Fast rotation of the N = Z nucleus Ar-36

Author

Svensson, Ce, Macchiavelli, Ao, Juodagalvis, A., Poves, A., Ragnarsson, I., Aberg, S., Appelbe, DE, Austin, Rae, Baktash, C., Ball, Gc, Michael Patten Carpenter, Caurier, E., Clark, Rm, Cromaz, M., Deleplanque, Ma, Diamond, Rm, Fallon, P., Furlotti, M., Galindo-Uribarri, A., Janssens, Rvf, Lane, Gj, Lee, Iy, Lipoglavsek, M., Nowacki, F., Paul, Sd, Radford, Dc, Sarantites, Dg, Seweryniak, D., Stephens, Fs, Tomov, V., Vetter, K., Ward, D., and Yu, Ch

41. Collective rotational motion in the N=Z nucleus Ar-36

Author

Svensson, Ce, Macchiavelli, Ao, Juodagalvis, A., Poves, A., Ragnarsson, I., Aberg, S., Appelbe, DE, Austin, Rae, Baktash, C., Ball, Gc, Michael Patten Carpenter, Caurier, E., Clark, Rm, Cromaz, M., Deleplanque, Ma, Diamond, Rm, Fallon, P., Furlotti, M., Galindo-Uribarri, A., Janssens, Rvf, Lane, Gj, Lee, Iy, Lipoglavsek, M., Nowacki, F., Paul, Sd, Radford, Dc, Sarantites, Dg, Seweryniak, D., Stephens, Fs, Tomov, V., Vetter, K., Ward, D., and Yu, Ch

42. COLLECTIVE OBLATE BANDS IN PB-196

Author

Hughes, Jr, Liang, Y., Janssens, Rvf, Kuhnert, A., Becker, Ja, Ahmad, I., Bearden, Ig, Brinkman, Mj, Burde, J., Carpenter, Mp, Cizewski, Ja, Daly, Pj, Deleplanque, Ma, Diamond, Rm, Draper, Je, Duyar, C., Bogdan Fornal, Garg, U., Grabowski, Zw, Henry, Ea, Henry, Rg, Hesselink, W., Kalantarnayestanaki, N., Kelly, Wh, Khoo, Tl, Lauritsen, T., Mayer, Rh, Nissius, D., Oliveira, Jrb, Plompen, Ajm, Reviol, W., Rubel, E., Soramel, F., Stephens, Fs, Stoyer, Ma, Vo, D., and Wang, Tf

Abstract

Evidence for collective oblate behavior in Pb196 is presented. One irregular and two regular bands of M1 transitions have been observed following the Er170(30Si,4n) and Yb176(26Mg,6n) reactions. Transitions linking the most intense regular band to the low-lying negative-parity yrast levels are observed, establishing excitation energies, spins, and probable parities of the band members. In contrast, no such transitions have been found for the irregular band and the weaker regular band. The bands are interpreted as corresponding to collective oblate rotation, arising mainly from deformation-aligned high-j, shape-driving quasiproton excitations across the Z=82 shell gap, coupled to rotation-aligned quasineutrons.

43. Multi-nucleon transfer reactions as a tool for spectroscopy of heavy nuclei

Author

Cocks, Jfc, Butler, Pa, Cann, Kj, Greenless, Pt, Jones, Gd, Smith, Jf, Jones, Pm, Julin, R., Juutinen, S., Muller, D., Piiparinen, M., Savelius, A., Broda, R., Bogdan Fornal, Ahmad, I., Blumenthal, Dj, Carpenter, Mp, Crowell, B., Janssens, Rvf, Khoo, Tl, Lauritsen, T., Nisius, D., Asztalos, S., Clark, Rm, Deleplanque, Ma, Diamond, Rm, Fallon, P., Lee, Iy, Macchiavelli, Ao, Macleod, Rw, Stephens, Fs, Bhattacharyya, P., and Zhang, Ct

44. Polymyxin Resistance in Clinical Isolates of K. pneumoniae in Brazil: Update on Molecular Mechanisms, Clonal Dissemination and Relationship With KPC-Producing Strains.

Author

Conceição-Neto OC, da Costa BS, Pontes LDS, Silveira MC, Justo-da-Silva LH, de Oliveira Santos IC, Teixeira CBT, Tavares E Oliveira TR, Hermes FS, Galvão TC, Antunes LCM, Rocha-de-Souza CM, and Carvalho-Assef APD

Subjects
Brazil, Humans, Microbial Sensitivity Tests, Multilocus Sequence Typing, Polymyxins adverse effects, Polymyxins pharmacology, Polymyxins therapeutic use, Anti-Bacterial Agents pharmacology, Anti-Bacterial Agents therapeutic use, Colistin pharmacology, Colistin therapeutic use, Drug Resistance, Bacterial drug effects, Drug Resistance, Bacterial genetics, Klebsiella Infections epidemiology, Klebsiella Infections genetics, Klebsiella pneumoniae genetics, Klebsiella pneumoniae isolation & purification, beta-Lactamases genetics, beta-Lactamases therapeutic use
Abstract

In Brazil, the production of KPC-type carbapenemases in Enterobacteriales is endemic, leading to widespread use of polymyxins. In the present study, 502 Klebsiella pneumoniae isolates were evaluated for resistance to polymyxins, their genetic determinants and clonality, in addition to the presence of carbapenem resistance genes and evaluation of antimicrobial resistance. Resistance to colistin (polymyxin E) was evaluated through initial selection on EMB agar containing 4% colistin sulfate, followed by Minimal Inhibitory Concentration (MIC) determination by broth microdilution. The susceptibility to 17 antimicrobials was assessed by disk diffusion. The presence of bla KPC , bla NDM and bla OXA-48-like carbapenemases was investigated by phenotypic methods and conventional PCR. Molecular typing was performed by PFGE and MLST. Allelic variants of the mcr gene were screened by PCR and chromosomal mutations in the pmrA , pmrB , phoP , phoQ and mgrB genes were investigated by sequencing. Our work showed a colistin resistance frequency of 29.5% (n = 148/502) in K. pneumoniae isolates. Colistin MICs from 4 to >128 µg/mL were identified (MIC 50 = 64 µg/mL; MIC 90 >128 µg/mL). All isolates were considered MDR, with the lowest resistance rates observed for amikacin (34.4%), and 19.6% of the isolates were resistant to all tested antimicrobials. The bla KPC gene was identified in 77% of the isolates, in consonance with the high rate of resistance to polymyxins related to its use as a therapeutic alternative. Through XbaI -PFGE, 51 pulsotypes were identified. MLST showed 21 STs, with ST437, ST258 and ST11 (CC11) being the most prevalent, and two new STs were determined: ST4868 and ST4869. The mcr-1 gene was identified in 3  K. pneumoniae isolates. Missense mutations in chromosomal genes were identified, as well as insertion sequences in mgrB . Furthermore, the identification of chromosomal mutations in K. pneumoniae isolates belonging from CC11 ensures its success as a high-risk epidemic clone in Brazil and worldwide., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Conceição-Neto, da Costa, Pontes, Silveira, Justo-da-Silva, de Oliveira Santos, Teixeira, Tavares e Oliveira, Hermes, Galvão, Antunes, Rocha-de-Souza and Carvalho-Assef.)

Published
2022
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45. Order-to-chaos transition in rotational nuclei.

Author

Stephens FS, Deleplanque MA, Lee IY, Macchiavelli AO, Ward D, Fallon P, Cromaz M, Clark RM, Descovich M, Diamond RM, and Rodriguez-Vieitez E

Abstract

We have developed a new method to study the order-to-chaos transition in rotational nuclei. Correlations between successive gamma rays are used to determine the average complexity of the intermediate levels and thereby the ratio of the interaction potential between levels to the level spacing. The measured ratios, 0.15 to 1.5, span the range from nearly fully ordered to nearly fully chaotic.

Published
2005
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46. Evidence for a new type of shears mechanism in 106Cd.

Author

Simons AJ, Wadsworth R, Jenkins DG, Clark RM, Cromaz M, Deleplanque MA, Diamond RM, Fallon P, Lane GJ, Lee IY, Macchiavelli AO, Stephens FS, Svensson CE, Vetter K, Ward D, and Frauendorf S

Abstract

Lifetimes of states in the lowest lying positive parity band in 106Cd have been measured using the Doppler shift attenuation method. The deduced B(E2) transition rates show a marked decrease with increasing spin. Cranking and semiclassical model calculations suggest that the structure has the character of a shears-type band resulting from the coupling of g(9/2) proton holes to aligned pairs of h(11/2) and g(7/2) neutron particles. This is the first clear evidence for the phenomenon of "antimagnetic" rotation in nuclei.

Published
2003
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47. Rotational damping in ytterbium nuclei.

Author

Stephens FS, Deleplanque MA, Lee IY, Ward D, Fallon P, Cromaz M, Clark RM, Diamond RM, Macchiavelli AO, and Vetter K

Abstract

We have made the first clear measurements of rotational damping widths in nuclei. In a mixture of three Yb nuclei, these widths are 300 +/- 60 keV between 1.2 and 1.5 MeV gamma-ray energy [approximately (37-57)Planck's constant]. Compound damping and motional narrowing are discussed in connection with these results.

Published
2002
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48. Very extended shapes in the A--110 region.

Author

Clark RM, Fallon P, Görgen A, Cromaz M, Deleplanque MA, Diamond RM, Lane GJ, Lee IY, Macchiavelli AO, Ramos RG, Stephens FS, Svensson CE, Vetter K, Ward D, Carpenter MP, Janssens RV, and Wadsworth R

Abstract

High-angular-momentum states in 108Cd were populated via the (64)Ni((48)Ca,4n) reaction at a beam energy of 207 MeV. Gamma rays were detected using the Gammasphere array. A rotational band has been observed with a dynamic moment of inertia and deduced lower limit of the quadrupole moment suggesting a major-to-minor axis ratio larger than 1.8:1, placing it among the most deformed structures identified in any nucleus, to date.

Published
2001
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50. Shears bands in 193Pb.

Author

Baldsiefen G, Stoyer MA, Cizewski JA, McNabb DP, Younes W, Becker JA, Bernstein LA, Brinkman MJ, Farris LP, Henry EA, Hughes JR, Kuhnert A, Wang TF, Cederwall B, Clark RM, Deleplanque MA, Diamond RM, Fallon P, Lee IY, Macchiavelli AO, Oliveira J, Stephens FS, Burde J, Vo DT, and Frauendorf S

Published
1996
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