Evidence for a spin-aligned neutron-proton paired phase from the level structure of Pd-92

B. Cederwall; F. Ghazi Moradi; T. Back; A. Johnson; J. Blomqvist; E. Clement; G. de France; R Wadsworth; K. Andgren; K. Lagergren; A. Dijon; G. Jaworski; R. Liotta; C. Qi; B. M. Nyako; J. Nyberg; M. Palacz; H. Al-Azri; A. Algora; G. de Angelis; A. Atac; S. Bhattacharyya; T. Brock; J. R. Brown; P. Davies; A. Di Nitto; Zs. Dombradi; A. Gadea; J. Gal; B. Hadinia; F. Johnston-Theasby; P. Joshi; K. Juhasz; R. Julin; A. Jungclaus; G. Kalinka; S. O. Kara; A. Khaplanov; J. Kownacki; G. La Rana; S. M. Lenzi; J. Molnar; R. Moro; D. R. Napoli; B. S. Nara Singh; A. Persson; F. Recchia; M. Sandzelius; J. -N. Scheurer; G. Sletten; D. Sohler; P. -A. Soderstrom; M. J. Taylor; J. Timar; J. J. Valiente-Dobon; E. Vardaci; S. Williams

doi:10.1038/nature09644

Evidence for a spin-aligned neutron-proton paired phase from the level structure of Pd-92

B. Cederwall, F. Ghazi Moradi, T. Back, A. Johnson, J. Blomqvist, E. Clement, G. de France, R Wadsworth, K. Andgren, K. Lagergren, A. Dijon, G. Jaworski, R. Liotta, C. Qi, B. M. Nyako, J. Nyberg, M. Palacz, H. Al-Azri, A. Algora, G. de AngelisA. Atac, S. Bhattacharyya, T. Brock, J. R. Brown, P. Davies, A. Di Nitto, Zs. Dombradi, A. Gadea, J. Gal, B. Hadinia, F. Johnston-Theasby, P. Joshi, K. Juhasz, R. Julin, A. Jungclaus, G. Kalinka, S. O. Kara, A. Khaplanov, J. Kownacki, G. La Rana, S. M. Lenzi, J. Molnar, R. Moro, D. R. Napoli, B. S. Nara Singh, A. Persson, F. Recchia, M. Sandzelius, J. -N. Scheurer, G. Sletten, D. Sohler, P. -A. Soderstrom, M. J. Taylor, J. Timar, J. J. Valiente-Dobon, E. Vardaci, S. Williams

Physics

Research output: Contribution to journal › Article › peer-review

Abstract

Shell structure and magic numbers in atomic nuclei were generally explained by pioneering work(1) that introduced a strong spin-orbit interaction to the nuclear shell model potential. However, knowledge of nuclear forces and the mechanisms governing the structure of nuclei, in particular far from stability, is still incomplete. In nuclei with equal neutron and proton numbers (N = Z), enhanced correlations arise between neutrons and protons (two distinct types of fermions) that occupy orbitals with the same quantum numbers. Such correlations have been predicted to favour an unusual type of nuclear superfluidity, termed isoscalar neutron-proton pairing(2-6), in addition to normal isovector pairing. Despite many experimental efforts, these predictions have not been confirmed. Here we report the experimental observation of excited states in the N = Z = 46 nucleus Pd-92. Gamma rays emitted following the Ni-58(Ar-36,2n)Pd-92 fusion-evaporation reaction were identified using a combination of state-of-the-art high-resolution c-ray, charged-particle and neutron detector systems. Our results reveal evidence for a spin-aligned, isoscalar neutron-proton coupling scheme, different from the previous prediction(2-6). We suggest that this coupling scheme replaces normal superfluidity (characterized by seniority coupling(7,8)) in the ground and low-lying excited states of the heaviest N = Z nuclei. Such strong, isoscalar neutron-proton correlations would have a considerable impact on the nuclear level structure and possibly influence the dynamics of rapid proton capture in stellar nucleosynthesis.

Original language	English
Pages (from-to)	68-71
Number of pages	4
Journal	Nature
Volume	469
Issue number	7328
DOIs	https://doi.org/10.1038/nature09644
Publication status	Published - 6 Jan 2011

Keywords

SHELL-MODEL DESCRIPTION
GENERALIZED SENIORITY
RICH NUCLEI
ISOSPIN
STATES

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http://www.nature.com/nature/journal/v469/n7328/full/nature09644.html

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Cederwall, B., Moradi, F. G., Back, T., Johnson, A., Blomqvist, J., Clement, E., de France, G., Wadsworth, R., Andgren, K., Lagergren, K., Dijon, A., Jaworski, G., Liotta, R., Qi, C., Nyako, B. M., Nyberg, J., Palacz, M., Al-Azri, H., Algora, A., ... Williams, S. (2011). Evidence for a spin-aligned neutron-proton paired phase from the level structure of Pd-92. Nature, 469(7328), 68-71. https://doi.org/10.1038/nature09644

@article{25c14c17a16845888cc5bf5ebe65975d,

title = "Evidence for a spin-aligned neutron-proton paired phase from the level structure of Pd-92",

abstract = "Shell structure and magic numbers in atomic nuclei were generally explained by pioneering work(1) that introduced a strong spin-orbit interaction to the nuclear shell model potential. However, knowledge of nuclear forces and the mechanisms governing the structure of nuclei, in particular far from stability, is still incomplete. In nuclei with equal neutron and proton numbers (N = Z), enhanced correlations arise between neutrons and protons (two distinct types of fermions) that occupy orbitals with the same quantum numbers. Such correlations have been predicted to favour an unusual type of nuclear superfluidity, termed isoscalar neutron-proton pairing(2-6), in addition to normal isovector pairing. Despite many experimental efforts, these predictions have not been confirmed. Here we report the experimental observation of excited states in the N = Z = 46 nucleus Pd-92. Gamma rays emitted following the Ni-58(Ar-36,2n)Pd-92 fusion-evaporation reaction were identified using a combination of state-of-the-art high-resolution c-ray, charged-particle and neutron detector systems. Our results reveal evidence for a spin-aligned, isoscalar neutron-proton coupling scheme, different from the previous prediction(2-6). We suggest that this coupling scheme replaces normal superfluidity (characterized by seniority coupling(7,8)) in the ground and low-lying excited states of the heaviest N = Z nuclei. Such strong, isoscalar neutron-proton correlations would have a considerable impact on the nuclear level structure and possibly influence the dynamics of rapid proton capture in stellar nucleosynthesis.",

keywords = "SHELL-MODEL DESCRIPTION, GENERALIZED SENIORITY, RICH NUCLEI, ISOSPIN, STATES",

author = "B. Cederwall and Moradi, {F. Ghazi} and T. Back and A. Johnson and J. Blomqvist and E. Clement and {de France}, G. and R Wadsworth and K. Andgren and K. Lagergren and A. Dijon and G. Jaworski and R. Liotta and C. Qi and Nyako, {B. M.} and J. Nyberg and M. Palacz and H. Al-Azri and A. Algora and {de Angelis}, G. and A. Atac and S. Bhattacharyya and T. Brock and Brown, {J. R.} and P. Davies and {Di Nitto}, A. and Zs. Dombradi and A. Gadea and J. Gal and B. Hadinia and F. Johnston-Theasby and P. Joshi and K. Juhasz and R. Julin and A. Jungclaus and G. Kalinka and Kara, {S. O.} and A. Khaplanov and J. Kownacki and {La Rana}, G. and Lenzi, {S. M.} and J. Molnar and R. Moro and Napoli, {D. R.} and Singh, {B. S. Nara} and A. Persson and F. Recchia and M. Sandzelius and Scheurer, {J. -N.} and G. Sletten and D. Sohler and Soderstrom, {P. -A.} and Taylor, {M. J.} and J. Timar and Valiente-Dobon, {J. J.} and E. Vardaci and S. Williams",

year = "2011",

month = jan,

day = "6",

doi = "10.1038/nature09644",

language = "English",

volume = "469",

pages = "68--71",

journal = "Nature",

issn = "0028-0836",

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number = "7328",

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Cederwall, B, Moradi, FG, Back, T, Johnson, A, Blomqvist, J, Clement, E, de France, G, Wadsworth, R, Andgren, K, Lagergren, K, Dijon, A, Jaworski, G, Liotta, R, Qi, C, Nyako, BM, Nyberg, J, Palacz, M, Al-Azri, H, Algora, A, de Angelis, G, Atac, A, Bhattacharyya, S, Brock, T, Brown, JR, Davies, P, Di Nitto, A, Dombradi, Z, Gadea, A, Gal, J, Hadinia, B, Johnston-Theasby, F, Joshi, P, Juhasz, K, Julin, R, Jungclaus, A, Kalinka, G, Kara, SO, Khaplanov, A, Kownacki, J, La Rana, G, Lenzi, SM, Molnar, J, Moro, R, Napoli, DR, Singh, BSN, Persson, A, Recchia, F, Sandzelius, M, Scheurer, J-N, Sletten, G, Sohler, D, Soderstrom, P-A, Taylor, MJ, Timar, J, Valiente-Dobon, JJ, Vardaci, E & Williams, S 2011, 'Evidence for a spin-aligned neutron-proton paired phase from the level structure of Pd-92', Nature, vol. 469, no. 7328, pp. 68-71. https://doi.org/10.1038/nature09644

TY - JOUR

T1 - Evidence for a spin-aligned neutron-proton paired phase from the level structure of Pd-92

AU - Cederwall, B.

AU - Moradi, F. Ghazi

AU - Back, T.

AU - Johnson, A.

AU - Blomqvist, J.

AU - Clement, E.

AU - de France, G.

AU - Wadsworth, R

AU - Andgren, K.

AU - Lagergren, K.

AU - Dijon, A.

AU - Jaworski, G.

AU - Liotta, R.

AU - Qi, C.

AU - Nyako, B. M.

AU - Nyberg, J.

AU - Palacz, M.

AU - Al-Azri, H.

AU - Algora, A.

AU - de Angelis, G.

AU - Atac, A.

AU - Bhattacharyya, S.

AU - Brock, T.

AU - Brown, J. R.

AU - Davies, P.

AU - Di Nitto, A.

AU - Dombradi, Zs.

AU - Gadea, A.

AU - Gal, J.

AU - Hadinia, B.

AU - Johnston-Theasby, F.

AU - Joshi, P.

AU - Juhasz, K.

AU - Julin, R.

AU - Jungclaus, A.

AU - Kalinka, G.

AU - Kara, S. O.

AU - Khaplanov, A.

AU - Kownacki, J.

AU - La Rana, G.

AU - Lenzi, S. M.

AU - Molnar, J.

AU - Moro, R.

AU - Napoli, D. R.

AU - Singh, B. S. Nara

AU - Persson, A.

AU - Recchia, F.

AU - Sandzelius, M.

AU - Scheurer, J. -N.

AU - Sletten, G.

AU - Sohler, D.

AU - Soderstrom, P. -A.

AU - Taylor, M. J.

AU - Timar, J.

AU - Valiente-Dobon, J. J.

AU - Vardaci, E.

AU - Williams, S.

PY - 2011/1/6

Y1 - 2011/1/6

N2 - Shell structure and magic numbers in atomic nuclei were generally explained by pioneering work(1) that introduced a strong spin-orbit interaction to the nuclear shell model potential. However, knowledge of nuclear forces and the mechanisms governing the structure of nuclei, in particular far from stability, is still incomplete. In nuclei with equal neutron and proton numbers (N = Z), enhanced correlations arise between neutrons and protons (two distinct types of fermions) that occupy orbitals with the same quantum numbers. Such correlations have been predicted to favour an unusual type of nuclear superfluidity, termed isoscalar neutron-proton pairing(2-6), in addition to normal isovector pairing. Despite many experimental efforts, these predictions have not been confirmed. Here we report the experimental observation of excited states in the N = Z = 46 nucleus Pd-92. Gamma rays emitted following the Ni-58(Ar-36,2n)Pd-92 fusion-evaporation reaction were identified using a combination of state-of-the-art high-resolution c-ray, charged-particle and neutron detector systems. Our results reveal evidence for a spin-aligned, isoscalar neutron-proton coupling scheme, different from the previous prediction(2-6). We suggest that this coupling scheme replaces normal superfluidity (characterized by seniority coupling(7,8)) in the ground and low-lying excited states of the heaviest N = Z nuclei. Such strong, isoscalar neutron-proton correlations would have a considerable impact on the nuclear level structure and possibly influence the dynamics of rapid proton capture in stellar nucleosynthesis.

AB - Shell structure and magic numbers in atomic nuclei were generally explained by pioneering work(1) that introduced a strong spin-orbit interaction to the nuclear shell model potential. However, knowledge of nuclear forces and the mechanisms governing the structure of nuclei, in particular far from stability, is still incomplete. In nuclei with equal neutron and proton numbers (N = Z), enhanced correlations arise between neutrons and protons (two distinct types of fermions) that occupy orbitals with the same quantum numbers. Such correlations have been predicted to favour an unusual type of nuclear superfluidity, termed isoscalar neutron-proton pairing(2-6), in addition to normal isovector pairing. Despite many experimental efforts, these predictions have not been confirmed. Here we report the experimental observation of excited states in the N = Z = 46 nucleus Pd-92. Gamma rays emitted following the Ni-58(Ar-36,2n)Pd-92 fusion-evaporation reaction were identified using a combination of state-of-the-art high-resolution c-ray, charged-particle and neutron detector systems. Our results reveal evidence for a spin-aligned, isoscalar neutron-proton coupling scheme, different from the previous prediction(2-6). We suggest that this coupling scheme replaces normal superfluidity (characterized by seniority coupling(7,8)) in the ground and low-lying excited states of the heaviest N = Z nuclei. Such strong, isoscalar neutron-proton correlations would have a considerable impact on the nuclear level structure and possibly influence the dynamics of rapid proton capture in stellar nucleosynthesis.

KW - SHELL-MODEL DESCRIPTION

KW - GENERALIZED SENIORITY

KW - RICH NUCLEI

KW - ISOSPIN

KW - STATES

UR - http://www.scopus.com/inward/record.url?scp=78650974098&partnerID=8YFLogxK

U2 - 10.1038/nature09644

DO - 10.1038/nature09644

M3 - Article

SN - 0028-0836

VL - 469

SP - 68

EP - 71

JO - Nature

JF - Nature

IS - 7328

ER -

Evidence for a spin-aligned neutron-proton paired phase from the level structure of Pd-92

Abstract

Keywords

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