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1. Shell evolution beyond N = 50 and Z = 28 : spectroscopy of 81,82,83,84Zn

Author

Shand, C. M. and Podolyák, Zs

Subjects
539.7
Abstract

The exotic region of the nuclear chart around the doubly-magic 78Ni (Z = 28, N = 50) nucleus presents an excellent testing ground for our understanding of nuclear structure. The region around N = 50 plays an important role in the astrophysical rapid neutron- capture (r) process. The robustness of the N = 50 conventional magic number could affect current knowledge of nuclear abundances. Measurements of 2+ and 4+ states offer one of the first indications of shell structure and evolution. Measurements of low-lying states in 81,82,83,84Zn were performed. 82,84Zn are the first two even-even nuclei beyond 78Ni, thus are an important test for the strength of the doubly-magic 78Ni core. The Zn nuclei were measured in the first and second experimental campaigns of the SEASTAR (Shell Evolution and Search for Two-plus energies At the RIBF) project conducted at the RIBF, RIKEN, Japan. In-flight fragmentation-fission beams were produced using a 238U primary beam of 345 MeV/nucleon. The BigRIPS spectrometer was used to identify and select the secondary beams impinged onto a liquid hydrogen target. γ rays were detected using DALI2, an array of 186 NaI detectors surrounding the target. The MINOS system provided vertex reconstruction by tracking the outgoing protons in (p, 2p) proton knockout reactions. Reaction products were identified using the ZeroDegree spectrometer. The 2+ and 4+ states in 82Zn were measured, the 4+1 was observed for the first time in this work along with two additional states. The 2+ and 4+ in 84Zn were measured for the first time, extending the known Zn systematics to N = 54. Two new transitions were observed and assigned within 81Zn, while two tentative transitions were seen in 83Zn. Two state-of-the-art shell model calculations were performed: Ni78-II utilised an inert 78Ni core with a large valence space, while the MCSM calculation allowed core-breaking configurations with a limited neutron valence space. Comparisons of these calculations to the results and region systematics have revealed that the breaking of the 78Ni core provides a significant contribution to low-lying states in the direct vicinity of 78Ni. However, the inclusion of core-breaking configurations also needs to be met with an ample model space to accommodate near future measurements of nuclei in the region. Interactions need to be developed to enable such accommodations in current shell-model calculations.

Published
2017

2. Competition between allowed and first-forbidden β decays of At208 and expansion of the Po208 level scheme

Author

Brunet, M., Podolyák, Zs., Berry, T. A., Brown, B. A., Carroll, R. J., Lica, R., Sotty, Ch., Andreyev, A. N., Borge, M. J. G., Cubiss, J. G., Fraile, L. M., Fynbo, H. O. U., Gamba, E., Greenlees, P., Harkness-Brennan, L. J., Huyse, M., Judson, D. S., Konki, J., Kurcewicz, J., Lazarus, I., Madurga, M., Marginean, N., Marginean, R., Marroquin, I., Mihai, C., Nácher, E., Negret, A., Pascu, S., Page, R. D., Perea, A., Phrompao, J., Piersa, M., Pucknell, V., Rahkila, P., Rapisarda, E., Regan, P. H., Rotaru, F., Rudigier, M., Shand, C. M., Shearman, R., Simpson, E. C., Stora, T., Tengblad, O., Van Duppen, P., Vedia, V., Vinals, S., Wadsworth, R., Warr, N., and De Witte, H.

Subjects
electromagnetic transitions, beta decay, fysiikka, nuclear structure and decays
Abstract

The structure of 208Po populated through the EC/β+ decay of 208At is investigated using γ-ray spectroscopy at the ISOLDE Decay Station. The presented level scheme contains 27 new excited states and 43 new transitions, as well as a further 50 previously observed γ rays which have been (re)assigned a position. The level scheme is compared to shell model calculations. Through this analysis approximately half of the β-decay strength of 208At is found to proceed via allowed decay and half via first-forbidden decay. The first-forbidden transitions predominantly populate core excited states at high excitation energies, which is qualitatively understood using shell model considerations. This mass region provides an excellent testing ground for the competition between allowed and first-forbidden β-decay calculations, important for the detailed understanding of the nucleosynthesis of heavy elements. peerReviewed

Published
2021

3. Competition between Allowed and First-Forbidden $beta$ Decay: The Case of $^208Hgrightarrow^208Tl$

Author

Carroll, R. J., Podolyák, Zs., Berry, T., Grawe, H., Alexander, T., Andreyev, A. N., Ansari, S., Borge, M. J. G., Brunet, M., Creswell, J. R., Fraile, L. M., Fahlander, C., Fynbo, H. O. U., Gamba, E. R., Gelletly, W., Gerst, R.-B., Górska, M., Gredley, A., Greenlees, P. T., Harkness-Brennan, L. J., Huyse, M., Judge, S. M., Judson, D. S., Konki, J., Kurcewicz, J., Kuti, I., Lalkovski, S., Lazarus, I. H., Licifmmode ăelse ă, R., Lund, M., Madurga, M., Marginean, N., Marginean, R., Marroquin, I., Mihai, C., Mihai, R. E., Nácher, E., Negret, A., Nita, C., Pascu, S., Page, R. D., Patel, Z., Perea, A., Phrompao, J., Piersa, M., Pucknell, V., Rahkila, P., Rapisarda, E., Regan, P. H., Rotaru, F., Rudigier, M., Shand, C. M., Shearman, R., Stegemann, S., Stora, T., Sotty, Ch., Tengblad, O., Van Duppen, P., Vedia, V., Wadsworth, R., Walker, P. M., Warr, N., Wearing, F., and De Witte, H.

Published
2020

4. Octupole states in Tl-207 studied through beta decay

Author

Berry, T. A., Podolyak, Zs, Carroll, R. J., Lica, R., Brown, B. A., Grawe, H., Sotty, Ch, Timofeyuk, N. K., Alexander, T., Andreyev, A. N., Ansari, S., Borge, M. J. G., Brunet, M., Cresswell, J. R., Fahlander, C., Fraile, L. M., Fynbo, H. O. U., Gamba, E., Gelletly, W., Gerst, R-B, Gorska, M., Gredley, A., Greenlees, P., Harkness-Brennan, L. J., Huyse, M., Judge, S. M., Judson, D. S., Konki, J., Kowalska, M., Kurcewicz, J., Kuti, I., Lalkovski, S., Lazarus, I., Lund, M., Madurga, M., Marginean, N., Mihai, C., Mihai, R. E., Nacher, E., Negret, A., Nae, S., Nita, C., Pascu, S., Page, R. D., Patel, Z., Perea, A., Phrompao, J., Piersa, M., Pucknell, V., Rahkila, P., Rapisarda, E., Regan, P. H., Rotaru, F., Rudigier, M., Shand, C. M., Shearman, R., Simpson, E. C., Stegemann, S., Stora, T., Tengblad, O., Turturica, A., Van Duppen, P., Vedia, V., Walker, P. M., Warr, N., Wearing, F. P., De Witte, H., and Helsinki Institute of Physics

Subjects
114 Physical sciences
Abstract

The beta decay of Hg-207 into the single-proton-hole nucleus Tl-207 has been studied through gamma-ray spectroscopy at the ISOLDE Decay Station (IDS) with the aim of identifying states resulting from coupling of the pi s(1/2)(-1), pi d(3/2)(-1) and pi h(11/2)(-1) shell model orbitals to the collective octupole vibration. Twenty-two states were observed lying between 2.6 and 4.0 MeV, eleven of which were observed for the first time, and 78 new transitions were placed. Two octupole states (s(3/2)-coupled) are identified and three more states (d(3/2)-coupled) are tentatively assigned using spin-parity inferences, while further h(11/2)-coupled states may also have been observed for the first time. Comparisons are made with state-of-the-art large-scale shell model calculations and previous observations made in this region, and systematic underestimation of the energy of the octupole vibrational states is noted. We suggest that in order to resolve the difference in predicted energies for collective and noncollective t = 1 states (t is the number of nucleons breaking the Pb-208 core), the effect of t = 2 mixing may be reduced for octupole-coupled states. The inclusion of mixing with t = 0, 2, 3 excitations is necessary to replicate all t = 1 state energies accurately.

Published
2020

5. Octupole states in $^{207}TI$ studied through $\beta$ decay

Author

Berry, T. A., Podolyák, Zs., Carroll, R. J., Lică, R., Brown, B. A., Grawe, Hubert, Sotty, Ch., Timofeyuk, N. K., Alexander, T., Andreyev, A. N., Ansari, S., Borge, M. J. G., Brunet, M., Cresswell, J. R., Fahlander, C., Fraile, L. M., Fynbo, H. O. U., Gamba, E., Gelletly, W., Gerst, R.-B., Górska, M., Gredley, A., Greenlees, P., Harkness-Brennan, L. J., Huyse, M., Judge, S. M., Judson, D. S., Konki, J., Kowalska, M., Kurcewicz, J., Kuti, I., Lalkovski, S., Lazarus, I., Lund, M., Madurga, M., Mărginean, N., Mărginean, R., Marroquin, I., Mihai, C., Mihai, R. E., Nácher, E., Negret, A., Nae, S., Niţă, C., Pascu, S., Page, R. D., Patel, Z., Perea, A., Phrompao, J., Piersa, M., Pucknell, V., Rahkila, P., Rapisarda, E., Regan, P. H., Rotaru, F., Rudigier, M., Shand, C. M., Shearman, R., Simpson, E. C., Stegemann, S., Stora, T., Tengblad, O., Turturica, A., Van Duppen, P., Vedia, V., Walker, P. M., Warr, N., Wearing, F. P., and De Witte, H.

Subjects
ddc:530
Abstract

Physical review / C 101(5), 054311 (2020). doi:10.1103/PhysRevC.101.054311, Published by APS, Woodbury, NY

Published
2020
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6. Octupole states in 207Tl studied through β decay

Author

Berry, T A, Podolyák, Zs, Carroll, R J, Lică, R, Brown, B A, Grawe, H, Sotty, Ch, Timofeyuk, N K, Alexander, T, Andreyev, A N, Ansari, S, Borge, M J G, Brunet, M, Cresswell, J R, Fahlander, C, Fraile, L M, Fynbo, H O U, Gamba, E, Gelletly, W, Gerst, R B, Górska, M, Gredley, A, Greenlees, P, Harkness-Brennan, L J, Huyse, M, Judge, S M, Judson, D S, Konki, J, Kowalska, M, Kurcewicz, J, Kuti, I, Lalkovski, S, Lazarus, I, Lund, M, Madurga, M, Mărginean, N, Mărginean, R, Marroquin, I, Mihai, C, Mihai, R E, Nácher, E, Negret, A, Nae, S, Niţă, C, Pascu, S, Page, R D, Patel, Z, Perea, A, Phrompao, J, Piersa, M, Pucknell, V, Rahkila, P, Rapisarda, E, Regan, P H, Rotaru, F, Rudigier, M, Shand, C M, Shearman, R, Simpson, E C, Stegemann, S, Stora, T, Tengblad, O, Turturica, A, Van Duppen, P, Vedia, V, Walker, P M, Warr, N, Wearing, F P, and De Witte, H

Subjects
nucleon distribution, Nuclear Physics - Experiment, collective levels, beta decay, ydinfysiikka, nuclear structure and decays
Abstract

The β decay of 207Hg into the single-proton-hole nucleus 207Tl has been studied through γ-ray spectroscopy at the ISOLDE Decay Station (IDS) with the aim of identifying states resulting from coupling of the πs−11/2, πd−13/2, and πh−111/2 shell model orbitals to the collective octupole vibration. Twenty-two states were observed lying between 2.6 and 4.0 MeV, eleven of which were observed for the first time, and 78 new transitions were placed. Two octupole states (s1/2-coupled) are identified and three more states (d3/2-coupled) are tentatively assigned using spin-parity inferences, while further h11/2-coupled states may also have been observed for the first time. Comparisons are made with state-of-the-art large-scale shell model calculations and previous observations made in this region, and systematic underestimation of the energy of the octupole vibrational states is noted. We suggest that in order to resolve the difference in predicted energies for collective and noncollective t=1 states (t is the number of nucleons breaking the 208Pb core), the effect of t=2 mixing may be reduced for octupole-coupled states. The inclusion of mixing with t=0,2,3 excitations is necessary to replicate all t=1 state energies accurately.

Published
2020
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7. Competition between Allowed and First-Forbidden β Decay : The Case of Hg208→Tl208

Author

Carroll, R. J., Podolyák, Zs., Berry, T., Grawe, H., Alexander, T., Andreyev, A. N., Ansari, S., Borge, M. J. G., Brunet, M., Creswell, J. R., Fraile, L. M., Fahlander, C., Fynbo, H. O. U., Gamba, E. R., Gelletly, W., Gerst, R.-B., Górska, M., Gredley, A., Greenlees, P. T., Harkness-Brennan, L. J., Huyse, M., Judge, S. M., Judson, D. S., Konki, J., Kurcewicz, J., Kuti, I., Lalkovski, S., Lazarus, I. H., Lică, R., Lund, M., Madurga, M., Marginean, N., Marginean, R., Marroquin, I., Mihai, C., Mihai, R. E., Nácher, E., Negret, A., Nita, C., Pascu, S., Page, R. D., Patel, Z., Perea, A., Phrompao, J., Piersa, M., Pucknell, V., Rahkila, P., Rapisarda, E., Regan, P. H., Rotaru, F., Rudigier, M., Shand, C. M., Shearman, R., Stegemann, S., Stora, T., Sotty, Ch., Tengblad, O., Van Duppen, P., Vedia, V., Wadsworth, R., Walker, P. M., Warr, N., Wearing, F., and De Witte, H.

Subjects
Nuclear Theory, Nuclear Experiment, ydinfysiikka, nuclear structure and decays
Abstract

The β decay of 208Hg into the one-proton hole, one neutron-particle 20881Tl127 nucleus was investigated at CERN-ISOLDE. Shell-model calculations describe well the level scheme deduced, validating the proton-neutron interactions used, with implications for the whole of the N>126, Z

Published
2020

8. Fast-timing measurements in the ground-state band of ¹¹⁴Pd

Author

Gamba, E. R., Bruce, A. M., Lalkovski, S., Rudigier, M., Bottoni, S., Carpenter, M. P., Zhu, S., Anderson, J. T., Ayangeakaa, A. D., Berry, T. A., Burrows, I., Gallardo, M. Carmona, Carroll, R. J., Copp, P., Cullen, D. M., Daniel, T., Martínez, G. Fernández, Greene, J. P., Gurgi, L. A., Hartley, D. J., Ilieva, R., Ilieva, S., Kondev, F. G., Kröll, T., Lane, G. J., Lauritsen, T., Lazarus, I., Lotay, G., Niţă, C. R., Podolyak, Zs., Pucknell, V., Reed, M., Regan, P. H., Rohrer, J., Sethi, J., Seweryniak, D., Shand, C. M., Simpson, J., Smoleń, M., Stefanova, E. A., Vedia, V., and Yordanov, O.

Abstract

Using a hybrid Gammasphere array coupled to 25 LaBr3(Ce) detectors, the lifetimes of the first three levels of the yrast band in ¹¹⁴Pd populated via ²⁵²Cf decay, have been measured. The measured lifetimes are τ₂+=103(10)ps, τ₄+=22(13)ps, and τ₆+≤10ps for the 2⁺₁, 4⁺₁, and 6⁺₁ levels, respectively. Palladium-114 was predicted to be the most deformed isotope of its isotopic chain, and spectroscopic studies have suggested it might also be a candidate nucleus for low-spin stable triaxiality. From the lifetimes measured in this work, reduced transition probabilities B(E2;J→J−2) are calculated and compared with interacting boson model, projected shell model, and collective model calculations from the literature. The experimental ratio RB(E₂)=B(E2;4⁺₁→2⁺₁)/B(E2;2⁺₁→0⁺₁)=0.80(42) is measured for the first time in ¹¹⁴Pd and compared with the known values RB(E₂) in the palladium isotopic chain: the systematics suggest that, for N=68, a transition from γ-unstable to a more rigid γ-deformed nuclear shape occurs.

Published
2019

9. Investigation of the Δn = 0 selection rule in Gamow-Teller transitions : The β-decay of 207 Hg

Author

Berry, T. A., Podolyák, Zs, Carroll, R. J., Lică, R., Grawe, H., Timofeyuk, N. K., Alexander, T., Andreyev, A. N., Ansari, S., Borge, M. J.G., Creswell, J., Fahlander, C., Fraile, L. M., Fynbo, H. O.U., Gelletly, W., Gerst, R. B., Górska, M., Gredley, A., Greenlees, P., Harkness-Brennan, L. J., Huyse, M., Judge, S. M., Judson, D. S., Konki, J., Kurcewicz, J., Kuti, I., Lalkovski, S., Lazarus, I., Lund, M., Madurga, M., Mărginean, N., Mărginean, R., Marroquin, I., Mihai, C., Mihai, R. E., Nácher, E., Nae, S., Negret, A., Niţă, C., Page, R. D., Pascu, S., Patel, Z., Perea, A., Pucknell, V., Rahkila, P., Rapisarda, E., Regan, P. H., Rotaru, F., Shand, C. M., Simpson, E. C., Sotty, Ch, Stegemann, S., Stora, T., Tengblad, O., Turturica, A., Van Duppen, P., Vedia, V., Wadsworth, R., Walker, P. M., Warr, N., Wearing, F., and De Witte, H.

Abstract

Gamow-Teller β decay is forbidden if the number of nodes in the radial wave functions of the initial and final states is different. This Δn=0 requirement plays a major role in the β decay of heavy neutron-rich nuclei, affecting the nucleosynthesis through the increased half-lives of nuclei on the astrophysical r-process pathway below both Z=50 (for N>82) and Z=82 (for N>126). The level of forbiddenness of the Δn=1ν1g 9/2 →π0g 7/2 transition has been investigated from the β − decay of the ground state of 207 Hg into the single-proton-hole nucleus 207 Tl in an experiment at the ISOLDE Decay Station. From statistical observational limits on possible γ-ray transitions depopulating the π0g 7/2 −1 state in 207 Tl, an upper limit of 3.9×10 −3 % was obtained for the probability of this decay, corresponding to log⁡ft>8.8 within a 95% confidence limit. This is the most stringent test of the Δn=0 selection rule to date.

Published
2019

10. Investigation of the Δn = 0 selection rule in Gamow-Teller transitions : The β-decay of 207Hg

Author

Berry, T. A., Podolyák, Zs., Carroll, R. J., Lică, R., Grawe, H., Timofeyuk, N. K., Alexander, T., Andreyev, A. N., Ansari, S., Borge, M. J. G., Creswell, J., Fynbo, H. O. U., Gelletly, W., Gerst, R.-B., Górska, M., Gredley, A., Greenlees, Paul, Harkness-Brennan, L. J., Huyse, M., Judge, S. M., Judson, D. S., Konki, Joonas, Kurcewicz, J., Kuti, I., Lalkovski, S., Lazarus, I., Lund, M., Madurga, M., Mărginean, N., Mărginean, R., Marroquin, I., Mihai, C., Mihai, R. E., Nácher, E., Nae, S., Negret, A., Niţă, C., Pascu, S., Page, R. D., Patel, Z., Perea, A., Pucknell, V., Rahkila, Panu, Rapisarda, E., Regan, P. H., Rotaru, F., Shand, C. M., Simpson, E. C., Sotty, Ch., Stegemann, S., Stora, T., Tengblad, O., Turturica, A., Van Duppen, P., Vedia, V., Wadsworth, R., Walker, P. M., Warr, N., Wearing, F., and De Witte, H.

Subjects
Gamow-Teller transitions, ydinfysiikka
Abstract

Gamow-Teller β decay is forbidden if the number of nodes in the radial wave functions of the initial and final states is different. This Δn = 0 requirement plays a major role in the β decay of heavy neutron-rich nuclei, affecting the nucleosynthesis through the increased half-lives of nuclei on the astrophysical r-process pathway below both Z = 50 (for N > 82) and Z = 82 (for N >126). The level of forbiddenness of the Δn = 1ν1g9/2 → π0g7/2 transition has been investigated from the β− decay of the ground state of 207Hg into the single-proton-hole nucleus 207Tl in an experiment at the ISOLDE Decay Station. From statistical observational limits on possible γ-ray transitions depopulating the π0g7/2−1 state in 207Tl, an upper limit of 3.9 × 10−3% was obtained for the probability of this decay, corresponding to log ft > 8.8 within a 95% confidence limit. This is the most stringent test of the Δn = 0 selection rule to date. peerReviewed

Published
2019

11. Doubly magic Pb 208: High-spin states, isomers, and E3 collectivity in the yrast decay

Author

Broda, R., Janssens, R. V. F., Iskra, L. W., Wrzesinski, J., Bogdan Fornal, Carpenter, M. P., Chiara, C. J., Cieplicka-Orynczak, N., Hoffman, C. R., Kondev, F. G., Krolas, W., Lauritsen, T., Podolyak, Zs, Seweryniak, D., Shand, C. M., Szpak, B., Walters, W. B., Zhu, S., and Brown, B. A.

Abstract

Yrast and near-yrast levels up to spin values in excess of I=30 have been delineated in the doubly magic Pb208 nucleus following deep-inelastic reactions involving Pb208 targets and, mostly, 430-MeV Ca48 and 1440-MeV Pb208 beams. The level scheme was established up to an excitation energy of 16.4 MeV, based on multifold γ-ray coincidence relationships measured with the Gammasphere array. Below the well-known, 0.5-μs 10+ isomer, ten new transitions were added to earlier work. The delineation of the higher parts of the level sequence benefited from analyses involving a number of prompt- and delayed-coincidence conditions. Three new isomeric states were established along the yrast line with Iπ=20- (10 342 keV), 23+ (11 361 keV), and 28- (13 675 keV), and respective half-lives of 22(3), 12.7(2), and 60(6) ns. Gamma transitions were also identified preceding in time the 28- isomer; however, only a few could be placed in the level scheme and no firm spin-parity quantum numbers could be proposed. In contrast, for most states below this 28- isomer, firm spin-parity values were assigned, based on total electron-conversion coefficients, deduced for low-energy (

Published
2017
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13. Validating (d,pγ) as a Surrogate for Neutron Capture.

Author

Ratkiewicz, A., Cizewski, J. A., Pain, S. D., Adekola, A. S., Burke, J. T., Casperson, R. J., Fotiades, N., McCleskey, M., Burcher, S., Shand, C. M., Austin, R. A. E., Baugher, T., Carpenter, M. P., Devlin, M., Escher, J. E., Hardy, S., Hatarik, R., Howard, M. E., Hughes, R. O., and Jones, K. L.

Subjects
NEUTRON capture, IRON, EXOTIC nuclei, NUCLEAR physics, NUCLEAR science
Abstract

The r-process is responsible for creating roughly half of the elements heavier than iron. It has recently become understood that the rates at which neutron capture reactions proceed at late times in the r-process may dramatically affect the final abundance pattern. However, direct measurements of neutron capture reaction rates on exotic nuclei are exceptionally difficult, necessitating the development of indirect approaches such as the surrogate technique. The (d,pγ) reaction at low energies was identified as a promising surrogate for the (n,γ) reaction, as both reactions share many characteristics. We report on a program to validate (d,pγ) as a surrogate for (n,γ) using 95Mo as a target. The experimental campaign includes direct measurements of the γ-ray intensities from the decay of excited states populated in the 95Mo(n,γ) and 95Mo(d,pγ) reactions. [ABSTRACT FROM AUTHOR]

Published
2015
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15. STRUCTURE OF 207Pb POPULATED IN 208Pb + 208Pb DEEP-INELASTIC COLLISIONS.

Author

SHAND, C. M., WILSON, E., PODOLYÁK, Z. S., GRAWE, H., BROWN, B. A., FORNAL, B., JANSSENS, R. V. F., BOWRY, M., BUNCE, M., CARPENTER, M. P., CARROLL, R. J., CHIARA, C. J., CIEPLICKA-ORYŃCZAK, N., DEO, A. Y., DRACOULIS, G. D., HOFFMAN, C. R., KEMPLEY, R. S., KONDEV, F. G., LANE, G. J., and LAURITSEN, T.

Subjects
*LEAD, *YRAST states, *INELASTIC collisions, *NUCLEAR structure, *GAMMASPHERE, *NUCLEAR shell theory, *NUCLEAR energy levels
Abstract

The yrast structure of 207Pb above the 13/2+ isomeric state has been investigated in deep-inelastic collisions of 208Pb and 208Pb at ATLAS, Argonne National Laboratory. New and previously observed transitions were measured using the Gammasphere detector array. The level scheme of 207Pb is presented up to ~ 6 MeV, built using coincidence and γ-ray intensity analyses. Spin and parity assignments of states were made, based on angular distributions and comparisons to shell model calculations. [ABSTRACT FROM AUTHOR]

Published
2015
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16. GAMMASPHERE AND ORRUBA: DUAL DETECTORS FOR EXPERIMENTAL STRUCTURE STUDIES.

Author

RATKIEWICZ, A., CIZEWSKI, J. A., HARDY, S., HOWARD, M. E., MANNING, B., SHAND, C. M., PAIN, S. D., BARDAYAN, D. W., MATOS, M., BLACKMON, J. C., CARPENTER, M. P., LISTER, C. J., SEWERYNIAK, D., ZHU, S., CHIPPS, K. A., JONES, K. L., KOZUB, R. L., and PETERS, W. A.

Subjects
GAMMASPHERE, NUCLEAR structure, NUCLEAR physics, QUASIPARTICLES, NEUTRONS
Published
2013

17. Field force data visualization: Developing an open mobile platform for integrated data access.

Author

McMorran, A. W., Rudd, S. E., Simmins, J. J., McCollough, N., and Shand, C. M.

Abstract

With the intention of supporting personnel in the field, this paper proposes a mobile application for data management and visualization. Taking advantage of modern mobile devices provides an inexpensive platform with built in sensors and power, providing field crews with important information regarding asset history, location and documentation while on the move. The use of such an application can also provide a platform for scheduling “real time” work requests and creating switching orders whilst in the vicinity of the asset, saving time and paper. [ABSTRACT FROM PUBLISHER]

Published
2012
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18. Addressing the challenge of data interoperability for off-line analysis of distribution networks in the Smart Grid.

Author

McMorran, A. W., Stewart, E. M., Shand, C. M., Rudd, S. E., and Taylor, G. A.

Abstract

As utilities move towards a more intelligent, autonomous distribution network with increased penetration of distributed generation there is a requirement for utilities and consultancies to analyze how these changes will affect network operation and performance under varying conditions. This requires a large amount of data and results to be moved on a frequent communications basis between applications from a number of different vendors, all of whom use their own proprietary data formats. This paper will discuss how these challenges are impacting off-line analysis of complex networks and how open standards can enable companies to efficiently share and exchange network models between incompatible applications. [ABSTRACT FROM PUBLISHER]

Published
2012
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19. Competition between Allowed and First-Forbidden β Decay: The Case of Hg 208 → Tl 208

Author

Carroll, R. J., Podolyák, Zs., Berry, T., Grawe, H., Alexander, T., Andreyev, A. N., Ansari, S., Borge, M. J. G., Brunet, M., Creswell, J. R., Fraile, L. M., Fahlander, C., Fynbo, H. O. U., Gamba, E. R., Gelletly, W., Gerst, R.-B., Górska, M., Gredley, A., Greenlees, P. T., Harkness-Brennan, L. J., Huyse, M., Judge, S. M., Judson, D. S., Konki, J., Kurcewicz, J., Kuti, I., Lalkovski, S., Lazarus, I. H., Lică, R., Lund, M., Madurga, M., Marginean, N., Marginean, R., Marroquin, I., Mihai, C., Mihai, R. E., Nácher, E., Negret, A., Nita, C., Pascu, S., Page, R. D., Patel, Z., Perea, A., Phrompao, J., Piersa, M., Pucknell, V., Rahkila, P., Rapisarda, E., Regan, P. H., Rotaru, F., Rudigier, M., Shand, C. M., Shearman, R., Stegemann, S., Stora, T., Sotty, Ch., Tengblad, O., Van Duppen, P., Vedia, V., Wadsworth, R., Walker, P. M., Warr, N., Wearing, F., and De Witte, H.

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20. Shell evolution beyond Z = 28 and N = 50: Spectroscopy of $^{81,82,83,84}$Zn

Author

Shand, C. M., Podolyák, Zs., Górska, M., Doornenbal, P., Obertelli, A., Nowacki, F., Otsuka, T., Sieja, K., Tostevin, J. A., Tsunoda, Y., Authelet, G., Baba, H., Calvet, D., Château, A., Chen, S., Corsi, A., Delbart, A., Gheller, J. M., Giganon, A., Gillibert, A., Isobe, T., Lapoux, V., Matsushita, M., Momiyama, S., Motobayashi, T., Niikura, M., Otsu, H., Paul, N., Péron, C., Peyaud, A., Pollacco, E. C., Roussé, J.-Y., Sakurai, H., Santamaria, C., Sasano, M., Shiga, Y., Steppenbeck, D., Takeuchi, S., Taniuchi, R., Uesaka, T., Wang, H., Yoneda, K., Ando, T., Arici, T., Blazhev, A., Browne, F., Bruce, A. M., Carroll, R. J., Chung, L. X., Cortés, M. L., Dewald, M., Ding, B., Dombrádi, Zs., Flavigny, F., Franchoo, S., Giacoppo, F., Gottardo, A., Hadyńska-Klęk, K., Jungclaus, A., Korkulu, Z., Koyama, S., Kubota, Y., Lee, J., Lettmann, M., Linh, B. D., Liu, J., Liu, Z., Lizarazo, C., Louchart, C., Lozeva, R., Matsui, K., Miyazaki, T., Moschner, K., Nagamine, M., Nakatsuka, N., Nishimura, S., Nita, C. R., Nobs, C. R., Olivier, L., Ota, S., Orlandi, R., Patel, Z., Regan, P. H., Rudigier, M., Şahin, E., Saito, T., Söderström, P.-A., Stefan, I., Sumikama, T., Suzuki, D., Vajta, Zs., Vaquero, V., Werner, V., Wimmer, K., Wu, J., and Xu, Z. Y.

Subjects
7. Clean energy
Abstract

Physics letters / B 773, 492 - 497 (2017). doi:10.1016/j.physletb.2017.09.001, Published by North-Holland Publ., Amsterdam

21. Octupole states in Tl 207 studied through β decay

Author

Berry, T. A., Podolyák, Zs, Carroll, R. J., Licǎ, R., Brown, B. A., Grawe, H., Sotty, Ch, Timofeyuk, N. K., Alexander, T., Andreyev, A. N., Ansari, S., Borge, M. J.G., Brunet, M., Cresswell, J. R., Fahlander, C., Fraile, L. M., Fynbo, H. O.U., Gamba, E., Gelletly, W., Gerst, R. B., Górska, M., Gredley, A., Greenlees, P., Harkness-Brennan, L. J., Huyse, M., Judge, S. M., Judson, D. S., Konki, J., Kowalska, M., Kurcewicz, J., Kuti, I., Lalkovski, S., Lazarus, I., Lund, M., Madurga, M., Mǎrginean, N., Mǎrginean, R., Marroquin, I., Mihai, C., Mihai, R. E., Nácher, E., Negret, A., Nae, S., Niţǎ, C., Pascu, S., Page, R. D., Patel, Z., Perea, A., Phrompao, J., Piersa, M., Pucknell, V., Rahkila, P., Rapisarda, E., Regan, P. H., Rotaru, F., Rudigier, M., Shand, C. M., Shearman, R., Simpson, E. C., Stegemann, S., Stora, T., Tengblad, O., Turturica, A., Van Duppen, P., Vedia, V., Walker, P. M., Warr, N., Wearing, F. P., and De Witte, H.

Abstract

The β decay of Hg207 into the single-proton-hole nucleus Tl207 has been studied through γ-ray spectroscopy at the ISOLDE Decay Station (IDS) with the aim of identifying states resulting from coupling of the πs1/2-1, πd3/2-1, and πh11/2-1 shell model orbitals to the collective octupole vibration. Twenty-two states were observed lying between 2.6 and 4.0 MeV, eleven of which were observed for the first time, and 78 new transitions were placed. Two octupole states (s1/2-coupled) are identified and three more states (d3/2-coupled) are tentatively assigned using spin-parity inferences, while further h11/2-coupled states may also have been observed for the first time. Comparisons are made with state-of-the-art large-scale shell model calculations and previous observations made in this region, and systematic underestimation of the energy of the octupole vibrational states is noted. We suggest that in order to resolve the difference in predicted energies for collective and noncollective t=1 states (t is the number of nucleons breaking the Pb208 core), the effect of t=2 mixing may be reduced for octupole-coupled states. The inclusion of mixing with t=0,2,3 excitations is necessary to replicate all t=1 state energies accurately.

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22. Octupole transitions in the 208Pb region.

Author

Podolyák, Zs, Shand, C. M., Wilson, E., Brown, B. A., Grawe, H., Chiara, C. J., Zhu, S., Fornal, B., Janssens, R. V. F., Bowry, M., Bunce, M., Carpenter, M. P., Cieplicka, N., Deo, A. Y., Dracoulis, G. D., Hoffman, C. R., Kempley, R. S., Kondev, F. G., Lane, G. J., and Lauritsen, T.

Published
2015
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23. Doubly magic 208Pb: High-spin states, isomers, and E3 collectivity in the yrast decay.

Author

Broda, R., Janssens, R. V. F., Iskra, Ł. W., Wrzesinski, J., Fornal, B., Carpenter, M. P., Chiara, C. J., Cieplicka-Oryńczak, N., Hoffman, C. R., Kondev, F. G., Królas, W., Lauritsen, T., Podolyak, Zs., Seweryniak, D., Shand, C. M., Szpak, B., Walters, W. B., Zhu, S., and Brown, B. A.

Subjects
*LEAD, *NUCLEAR isomers, *YRAST states
Abstract

Yrast and near-yrast levels up to spin values in excess of I=30ħ have been delineated in the doubly magic 208Pb nucleus following deep-inelastic reactions involving 208Pb targets and, mostly, 430-MeV 48Ca and 1440-MeV 208Pb beams. The level scheme was established up to an excitation energy of 16.4 MeV, based on multifold γ-ray coincidence relationships measured with the Gammasphere array. Below the well-known, 0.5-µs 10+ isomer, ten new transitions were added to earlier work. The delineation of the higher parts of the level sequence benefited from analyses involving a number of prompt- and delayed-coincidence conditions. Three new isomeric states were established along the yrast line with Ip=20-(10342 keV), 23+ (11361 keV), and 28- (13675 keV), and respective half-lives of 22(3), 12.7(2), and 60(6) ns. Gamma transitions were also identified preceding in time the 28- isomer; however, only a few could be placed in the level scheme and no firm spin-parity quantum numbers could be proposed. In contrast, for most states below this 28- isomer, firm spin-parity values were assigned, based on total electron-conversion coefficients, deduced for low-energy (<500keV) transitions from γ-intensity balances, and on measured γ-ray angular distributions. The latter also enabled the quantitative determination of mixing ratios. The transition probabilities extracted for all isomeric transitions in 208Pb have been reviewed and discussed in terms of the intrinsic structure of the initial and final levels involved. Particular emphasis was placed on the many observed E3 transitions as they often exhibit significant enhancements in strength [of the order of tens of Weisskopf units (W.u.)] comparable to the one seen for the neutron j15/2γg9/2 E3 transition in 209Pb. In this context, the enhancement of the 725-keV E3 transition (56 W.u.) associated with the decay of the highest-lying 28- isomer observed in this work remains particularly challenging to explain. Large-scale shell-model calculations were performed with two approaches, a first one where the 1, 2, and 3 particle-hole excitations do not mix with one another, and another more complex one, in which such mixing takes place. The calculated levels were compared with the data and a general agreement is observed for most of the 208Pb level scheme. At the highest spins and energies, however, the correspondence between theory and experiment is less satisfactory and the experimental yrast line appears to be more regular than the calculated one. This regularity is notable when the level energies are plotted versus the I(I+1) product and the observed, nearly linear, behavior was considered within a simple "rotational" interpretation. Within this approximate picture, the extracted moment of inertia suggests that only the 76 valence nucleons participate in the "rotation" and that the 132Sn spherical core remains inert. [ABSTRACT FROM AUTHOR]

Published
2017
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24. Competition between Allowed and First-Forbidden β Decay: The Case of ^{208}Hg→^{208}Tl.

Author

Carroll RJ, Podolyák Z, Berry T, Grawe H, Alexander T, Andreyev AN, Ansari S, Borge MJG, Brunet M, Creswell JR, Fraile LM, Fahlander C, Fynbo HOU, Gamba ER, Gelletly W, Gerst RB, Górska M, Gredley A, Greenlees PT, Harkness-Brennan LJ, Huyse M, Judge SM, Judson DS, Konki J, Kurcewicz J, Kuti I, Lalkovski S, Lazarus IH, Lică R, Lund M, Madurga M, Marginean N, Marginean R, Marroquin I, Mihai C, Mihai RE, Nácher E, Negret A, Nita C, Pascu S, Page RD, Patel Z, Perea A, Phrompao J, Piersa M, Pucknell V, Rahkila P, Rapisarda E, Regan PH, Rotaru F, Rudigier M, Shand CM, Shearman R, Stegemann S, Stora T, Sotty C, Tengblad O, Van Duppen P, Vedia V, Wadsworth R, Walker PM, Warr N, Wearing F, and De Witte H

Abstract

The β decay of ^{208}Hg into the one-proton hole, one neutron-particle &#95;{81}^{208}Tl&#95;{127} nucleus was investigated at CERN-ISOLDE. Shell-model calculations describe well the level scheme deduced, validating the proton-neutron interactions used, with implications for the whole of the N>126, Z<82 quadrant of neutron-rich nuclei. While both negative and positive parity states with spin 0 and 1 are expected within the Q&#95;{β} window, only three negative parity states are populated directly in the β decay. The data provide a unique test of the competition between allowed Gamow-Teller and Fermi, and first-forbidden β decays, essential for the understanding of the nucleosynthesis of heavy nuclei in the rapid neutron capture process. Furthermore, the observation of the parity changing 0^{+}→0^{-}β decay where the daughter state is core excited is unique, and can provide information on mesonic corrections of effective operators.

Published
2020
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25. Role of the Δ Resonance in the Population of a Four-Nucleon State in the ^{56}Fe→^{54}Fe Reaction at Relativistic Energies.

Author

Podolyák Z, Shand CM, Lalović N, Gerl J, Rudolph D, Alexander T, Boutachkov P, Cortés ML, Górska M, Kojouharov I, Kurz N, Louchart C, Merchán E, Michelagnoli C, Pérez-Vidal RM, Pietri S, Ralet D, Reese M, Schaffner H, Stahl C, Weick H, Ameil F, de Angelis G, Arici T, Carroll R, Dombrádi Z, Gadea A, Golubev P, Lettmann M, Lizarazo C, Mahboub D, Pai H, Patel Z, Pietralla N, Regan PH, Sarmiento LG, Wieland O, Wilson E, Birkenbach B, Bruyneel B, Burrows I, Charles L, Clément E, Crespi FC, Cullen DM, Désesquelles P, Eberth J, González V, Habermann T, Harkness-Brennan L, Hess H, Judson DS, Jungclaus A, Korten W, Labiche M, Maj A, Mengoni D, Napoli DR, Pullia A, Quintana B, Rainovski G, Reiter P, Salsac MD, Sanchis E, and Valiente Dóbon JJ

Abstract

The ^{54}Fe nucleus was populated from a ^{56}Fe beam impinging on a Be target with an energy of E/A=500  MeV. The internal decay via γ-ray emission of the 10^{+} metastable state was observed. As the structure of this isomeric state has to involve at least four unpaired nucleons, it cannot be populated in a simple two-neutron removal reaction from the ^{56}Fe ground state. The isomeric state was produced in the low-momentum (-energy) tail of the parallel momentum (energy) distribution of ^{54}Fe, suggesting that it was populated via the decay of the Δ^{0} resonance into a proton. This process allows the population of four-nucleon states, such as the observed isomer. Therefore, it is concluded that the observation of this 10^{+} metastable state in ^{54}Fe is a consequence of the quark structure of the nucleons.

Published
2016
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