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1. Lifetime measurements of yrast states in ¹⁷⁸ Pt using the charge plunger method with a recoil separator

Author

Heery, J. (J.), Barber, L. (L.), Vilhena, J. (J.), Singh, B. S. (B. S. Nara), Herzberg, R. -. (R. -D.), Cullen, D. M. (D. M.), Mueller-Gatermann, C. (C.), Beeton, G. (G.), Bowry, M. (M.), Dewald, A. (A.), Grahn, T. (T.), Greenlees, P. T. (P. T.), Illana, A. (A.), Julin, R. (R.), Juutinen, S. (S.), Keatings, J. M. (J. M.), Leino, M. (M.), Luoma, M. (M.), O'Donnell, D. (D.), Ojala, J. (J.), Pakarinen, J. (J.), Rahkila, P. (P.), Ruotsalainen, P. (P.), Sandzelius, M. (M.), Saren, J. (J.), Sinclair, J. (J.), Smith, J. F. (J. F.), Sorri, J. (J.), Spagnoletti, P. (P.), Tann, H. (H.), Uusitalo, J. (J.), Zimba, G. (G.), Heery, J. (J.), Barber, L. (L.), Vilhena, J. (J.), Singh, B. S. (B. S. Nara), Herzberg, R. -. (R. -D.), Cullen, D. M. (D. M.), Mueller-Gatermann, C. (C.), Beeton, G. (G.), Bowry, M. (M.), Dewald, A. (A.), Grahn, T. (T.), Greenlees, P. T. (P. T.), Illana, A. (A.), Julin, R. (R.), Juutinen, S. (S.), Keatings, J. M. (J. M.), Leino, M. (M.), Luoma, M. (M.), O'Donnell, D. (D.), Ojala, J. (J.), Pakarinen, J. (J.), Rahkila, P. (P.), Ruotsalainen, P. (P.), Sandzelius, M. (M.), Saren, J. (J.), Sinclair, J. (J.), Smith, J. F. (J. F.), Sorri, J. (J.), Spagnoletti, P. (P.), Tann, H. (H.), Uusitalo, J. (J.), and Zimba, G. (G.)

Abstract

Lifetime measurements in \(^{178}\)Pt with excited states de-exciting through \(\gamma\)-ray transitions and internal electron conversions have been performed. Ionic charges were selected by the in-flight mass separator MARA and measured at the focal plane in coincidence with the \(4^{+}_{1}→2^{+}_{1}\) 257 keV γ-ray transition detected using the JUROGAM 3 spectrometer. The resulting charge-state distributions were analysed using the differential decay curve method (DDCM) framework to obtain a lifetime value of 430(20) ps for the \(2^{+}_{1}\) state. This work builds on a method that combines the charge plunger technique with the DDCM analysis. As an alternative analysis, ions were selected in coincidence with the \(^{178}\)Pt alpha decay (\(E_{\mathrm {alpha}} = 5.458(5)\) MeV) at the focal plane. Lifetime information was obtained by fitting a two-state Bateman equation to the decay curve with the lifetime of individual states defined by a single quadrupole moment. This yielded a lifetime value of 430(50) ps for the \(2^{+}_{1}\) state, and 54(6) ps for the \(4^{+}_{1}\) state. An analysis method based around the Bateman equation will become especially important when using the charge plunger method for the cases where utilising coincidences between prompt \(\gamma\) rays and recoils is not feasible.

Published
2021

2. Lifetime measurements of excited states in 169,171,173Os:persistence of anomalous B(E2) ratios in transitional rare earth nuclei in the presence of a decoupled i13/2 valence neutron

Author

Zhang, W. (W.), Cederwall, B. (B.), Doncel, M. (M.), Aktas, O. (O.), Ertoprak, A. (A.), Liotta, R. (R.), Qi, C. (C.), Grahn, T. (T.), Singh, B. S. (B. S. Nara), Cullen, D. M. (D. M.), Hodge, D. (D.), Giles, M. (M.), Stolze, S. (S.), Badran, H. (H.), Braunroth, T. (T.), Calverley, T. (T.), Cox, D. M. (D. M.), Fang, Y. D. (Y. D.), Greenlees, P. T. (P. T.), Hilton, J. (J.), Ideguchi, E. (E.), Julin, R. (R.), Juutinen, S. (S.), Raju, M. K. (M. Kumar), Li, H. (H.), Liu, H. (H.), Matta, S. (S.), Subramaniam, P. (P.), Modamio, V. (V), Pakarinen, J. (J.), Papadakis, P. (P.), Partanen, J. (J.), Petrache, C. M. (C. M.), Rahkila, P. (P.), Ruotsalainen, P. (P.), Sandzelius, M. (M.), Saren, J. (J.), Scholey, C. (C.), Sorri, J. (J.), Taylor, M. J. (M. J.), Uusitalo, J. (J.), Valiente-Dobon, J. J. (J. J.), Zhang, W. (W.), Cederwall, B. (B.), Doncel, M. (M.), Aktas, O. (O.), Ertoprak, A. (A.), Liotta, R. (R.), Qi, C. (C.), Grahn, T. (T.), Singh, B. S. (B. S. Nara), Cullen, D. M. (D. M.), Hodge, D. (D.), Giles, M. (M.), Stolze, S. (S.), Badran, H. (H.), Braunroth, T. (T.), Calverley, T. (T.), Cox, D. M. (D. M.), Fang, Y. D. (Y. D.), Greenlees, P. T. (P. T.), Hilton, J. (J.), Ideguchi, E. (E.), Julin, R. (R.), Juutinen, S. (S.), Raju, M. K. (M. Kumar), Li, H. (H.), Liu, H. (H.), Matta, S. (S.), Subramaniam, P. (P.), Modamio, V. (V), Pakarinen, J. (J.), Papadakis, P. (P.), Partanen, J. (J.), Petrache, C. M. (C. M.), Rahkila, P. (P.), Ruotsalainen, P. (P.), Sandzelius, M. (M.), Saren, J. (J.), Scholey, C. (C.), Sorri, J. (J.), Taylor, M. J. (M. J.), Uusitalo, J. (J.), and Valiente-Dobon, J. J. (J. J.)

Abstract

Lifetimes of low-lying excited states in the vi13/2⁺ bands of the neutron-deficient osmium isotopes 169,171,173Os have been measured for the first time using the recoil-distance Doppler shift and recoil-isomer tagging techniques. An unusually low value is observed for the ratio B(E2; 21/2⁺ → 17/2⁺) /B(E2; 17/2⁺ → 13/2⁺) in 169Os, similar to the “anomalously” low values of the ratio B(E2; 4⁺1 → 2⁺1 )/B(E2; 2⁺1 → 0⁺gs) previously observed in several transitional rare-earth nuclides with even numbers of neutrons and protons, including the neighboring 168,170Os. Furthermore, the evolution of B(E2; 21/2⁺→ 17/2⁺)/B(E2; 17/2⁺ → 13/2⁺) with increasing neutron number in the odd-mass isotopic chain 169,171,173Os is observed to follow the same trend as observed previously in the even-even Os isotopes. These findings indicate that the possible quantum phase transition from a seniority conserving structure to a collective regime as a function of neutron number suggested for the even-even systems is maintained in these odd-mass osmium nuclei, with the odd valence neutron merely acting as a “spectator”. As for the even-even nuclei, the phenomenon is highly unexpected for nuclei that are not situated near closed shells.

Published
2021

3. High-spin states of ²¹⁸Th

Author

O'Donnell, D. (D.), Page, R. D. (R. D.), Grahn, T. (T.), Ali, F. A. (F. A.), Auranen, K. (K.), Capponi, L. (L.), Carroll, R. J. (R. J.), Chishti, M. M. (M. M. R.), Drummond, M. C. (M. C.), Greenlees, P. T. (P. T.), Henderson, J. (J.), Herzan, A. (A.), Jakobsson, U. (U.), Joss, D. T. (D. T.), Julin, R. (R.), Juutinen, S. (S.), Konki, J. (J.), Labiche, M. (M.), Leino, M. (M.), Mason, P. J. (P. J. R.), McPeake, C. G. (C. G.), Pakarinen, J. (J.), Papadakis, P. (P.), Partanen, J. (J.), Peura, P. (P.), Rahkila, P. (P.), Revill, J. (J.), Ruotsalainen, P. (P.), Sandzelius, M. (M.), Saren, J. (J.), Saygi, B. (B.), Scholey, C. (C.), Simpson, J. (J.), Smith, J. F. (J. F.), Smolen, M. (M.), Sorri, J. (J.), Stolze, S. (S.), Sullivan, C. M. (C. M.), Thornthwaite, A. (A.), Uusitalo, J. (J.), Kumar, A. (A.), and Srivastava, P. C. (P. C.)

Subjects
fusion-evaporation reactions, gamma-ray spectroscopy, shell model, alpha-decay, Nuclear Experiment, thorium
Abstract

High-spin states in the N = 128 nucleus ²¹⁸Th have been investigated following fusion–evaporation reactions, using the recoil-decay tagging technique. Due to the short-lived nature of the ground state of ²¹⁸Th prompt γ rays have been correlated with the α decay of the daughter nucleus ²¹⁴Ra. The level scheme representing the decay of excited states has been extended to (16⁺) with the observation of six previously unreported transitions. The observations are compared with the results of shell model calculations and within the context of the systematics of neighbouring nuclei.

Published
2020

4. A charge plunger device to measure the lifetimes of excited nuclear states where transitions are dominated by internal conversion

Author

Barber, L. (L.), Heery, J. (J.), Cullen, D. M. (D. M.), Singh, B. S. (B. S. Nara), Herzberg, R.-D. (R.-D.), Müller-Gatermann, C. (C.), Beeton, G. (G.), Bowry, M. (M.), Dewald, A. (A.), Grahn, T. (T.), Greenlees, P. T. (P. T.), Illana, A. (A.), Julin, R. (R.), Juutinen, S. (S.), Keatings, J. M. (J. M.), Luoma, M. (M.), O’Donnell, D. (D.), Ojala, J. (J.), Pakarinen, J. (J.), Rahkila, P. (P.), Ruotsalainen, P. (P.), Sandzelius, M. (M.), Sarén, J. (J.), Sinclair, J. (J.), Smith, J. F. (J. F.), Sorri, J. (J.), Spagnoletti, P. (P.), Tann, H. (H.), Uusitalo, J. (J.), Vilhena, J. (J.), and Zimba, G. (G.)

Subjects
DDCM, Plunger, RDDS, Charge plunger, Nuclear-state lifetimes
Abstract

A charge plunger device has been commissioned based on the DPUNS plunger (Taylor et al., 2013) using the in-flight mass separator MARA at the University of Jyväskylä. The ¹⁵²Sm(³²S,4n)¹⁸⁰ reaction was used to populate excited states in ¹⁸⁰. A lifetime measurement of the state \(2_1^+\) was performed by applying the charge plunger technique, which relies on the detection of the charge state-distribution of recoils rather than the detection of the emitted γ rays. This state was a good candidate to test the charge plunger technique as it has a known lifetime and depopulates through a converted transition that competes strongly with γ-ray emission. The lifetime of the \(2_1^+\) state was measured to be 480(10)ps, which is consistent with previously reported lifetimes that relied on the standard γ-ray techniques. The charge plunger technique is a complementary approach to lifetime measurements of excited states that depopulate through both γ-ray emission and internal conversion. In cases where it is not possible to detect Doppler-shifted γ rays, for example, in heavy nuclei where internal conversion dominates, it may well be the only feasible lifetime analysis approach.

Published
2020

5. In-beam γ-ray and electron spectroscopy of ²⁴⁹,²⁵¹Md

Author

Briselet, R. (R.), Theisen, C. (Ch), Sulignano, B. (B.), Airiau, M. (M.), Auranen, K. (K.), Cox, D. M. (D. M.), Dechery, F. (F.), Drouart, A. (A.), Favier, Z. (Z.), Gall, B. (B.), Goigoux, T. (T.), Grahn, T. (T.), Greenlees, P. T. (P. T.), Hauschild, K. (K.), Herzan, A. (A.), Herzberg, R.-D. (R-D), Jakobsson, U. (U.), Julin, R. (R.), Juutinen, S. (S.), Konki, J. (J.), Leino, M. (M.), Lopez-Martens, A. (A.), Mistry, A. (A.), Nieminen, P. (P.), Pakarinen, J. (J.), Papadakis, P. (P.), Peura, P. (P.), Rey-Herme, E. (E.), Rahkila, P. (P.), Rubert, J. (J.), Ruotsalainen, P. (P.), Sandzelius, M. (M.), Saren, J. (J.), Scholey, C. (C.), Sorri, J. (J.), Stolze, S. (S.), Uusitalo, J. (J.), Vandebrouck, M. (M.), Ward, A. (A.), Zielinska, M. (M.), Bally, B. (B.), Bender, M. (M.), and Ryssens, W. (W.)

Abstract

The odd-Z ²⁵¹Md nucleus was studied using combined γ-ray and conversion-electron in-beam spectroscopy. Besides the previously observed rotational band based on the [521]1/2⁻ configuration, another rotational structure has been identified using γ−γ coincidences. The use of electron spectroscopy allowed the rotational bands to be observed over a larger rotational frequency range. Using the transition intensities that depend on the gyromagnetic factor, a [514]7/2⁻ single-particle configuration has been inferred for this band, i.e., the ground-state band. A physical background that dominates the electron spectrum with an intensity of ≃60% was well reproduced by simulating a set of unresolved excited bands. Moreover, a detailed analysis of the intensity profile as a function of the angular momentum provided a method for deriving the orbital gyromagnetic factor, namely \(g_{K}=0.69^{+0.19}_{−0.16}\) for the ground-state band. The odd-Z ²⁴⁹Md was studied using γ-ray in-beam spectroscopy. Evidence for octupole correlations resulting from the mixing of the Δl=Δj=3 [521]3/2⁻ and [633]7/2⁺ Nilsson orbitals were found in both ²⁴⁹,²⁵¹Md. A surprising similarity of the²⁵¹Md ground-state band transition energies with those of the excited band of ²⁵⁵Lr has been discussed in terms of identical bands. Skyrme-Hartree-Fock-Bogoliubov calculations were performed to investigate the origin of the similarities between these bands.

Published
2020

6. First candidates for γ vibrational bands built on the [505]11/2⁻ neutron orbital in odd-A Dy isotopes

Author

Majola, S. N. (S. N. T.), Sithole, M. A. (M. A.), Mdletshe, L. (L.), Hartley, D. (D.), Timar, J. (J.), Nyako, B. M. (B. M.), Allmond, J. M. (J. M.), Bark, R. A. (R. A.), Beausang, C. (C.), Bianco, L. (L.), Bucher, T. D. (T. D.), Bvumbi, S. P. (S. P.), Carpenter, M. P. (M. P.), Chiara, C. J. (C. J.), Cooper, N. (N.), Cullen, D. M. (D. M.), Curien, D. (D.), Dinoko, T. S. (T. S.), Gall, B. J. (B. J. P.), Garrett, P. E. (P. E.), Greenlees, P. T. (P. T.), Hirvonen, J. (J.), Jakobsson, U. (U.), Jones, P. M. (P. M.), Julin, R. (R.), Juutinen, S. (S.), Ketelhut, S. (S.), Kheswa, B. V. (B., V), Kondev, F. G. (F. G.), Korichi, A. (A.), Kulp, W. D. (W. D.), Lauritsen, T. (T.), Lawrie, E. A. (E. A.), Makhathini, L. (L.), Masiteng, P. L. (P. L.), Maqabuka, B. (B.), McCutchan, E. A. (E. A.), Miller, D. (D.), Miller, S. (S.), Minkova, A. (A.), Msebi, L. (L.), Mthembu, S. H. (S. H.), Ndayishimye, J. (J.), Nieminen, P. (P.), Ngcobo, P. Z. (P. Z.), Ntshangase, S. S. (S. S.), Orce, J. N. (J. N.), Peura, P. (P.), Rahkila, P. (P.), Redon, N. (N.), Riedinger, L. L. (L. L.), Riley, M. A. (M. A.), Roux, D. G. (D. G.), Ruotsalainen, P. (P.), Piot, J. (J.), Saren, J. (J.), Sharpey-Schafer, J. F. (J. F.), Scholey, C. (C.), Shirinda, O. (O.), Simpson, J. (J.), Sorri, J. (J.), Stefanescu, I. (I), Stolze, S. (S.), Uusitalo, J. (J.), Wang, X. (X.), Werner, V. (V), Wood, J. L. (J. L.), Yu, C.-H. (C-H), Zhu, S. (S.), Zimba, G. (G.), Majola, S. N. (S. N. T.), Sithole, M. A. (M. A.), Mdletshe, L. (L.), Hartley, D. (D.), Timar, J. (J.), Nyako, B. M. (B. M.), Allmond, J. M. (J. M.), Bark, R. A. (R. A.), Beausang, C. (C.), Bianco, L. (L.), Bucher, T. D. (T. D.), Bvumbi, S. P. (S. P.), Carpenter, M. P. (M. P.), Chiara, C. J. (C. J.), Cooper, N. (N.), Cullen, D. M. (D. M.), Curien, D. (D.), Dinoko, T. S. (T. S.), Gall, B. J. (B. J. P.), Garrett, P. E. (P. E.), Greenlees, P. T. (P. T.), Hirvonen, J. (J.), Jakobsson, U. (U.), Jones, P. M. (P. M.), Julin, R. (R.), Juutinen, S. (S.), Ketelhut, S. (S.), Kheswa, B. V. (B., V), Kondev, F. G. (F. G.), Korichi, A. (A.), Kulp, W. D. (W. D.), Lauritsen, T. (T.), Lawrie, E. A. (E. A.), Makhathini, L. (L.), Masiteng, P. L. (P. L.), Maqabuka, B. (B.), McCutchan, E. A. (E. A.), Miller, D. (D.), Miller, S. (S.), Minkova, A. (A.), Msebi, L. (L.), Mthembu, S. H. (S. H.), Ndayishimye, J. (J.), Nieminen, P. (P.), Ngcobo, P. Z. (P. Z.), Ntshangase, S. S. (S. S.), Orce, J. N. (J. N.), Peura, P. (P.), Rahkila, P. (P.), Redon, N. (N.), Riedinger, L. L. (L. L.), Riley, M. A. (M. A.), Roux, D. G. (D. G.), Ruotsalainen, P. (P.), Piot, J. (J.), Saren, J. (J.), Sharpey-Schafer, J. F. (J. F.), Scholey, C. (C.), Shirinda, O. (O.), Simpson, J. (J.), Sorri, J. (J.), Stefanescu, I. (I), Stolze, S. (S.), Uusitalo, J. (J.), Wang, X. (X.), Werner, V. (V), Wood, J. L. (J. L.), Yu, C.-H. (C-H), Zhu, S. (S.), and Zimba, G. (G.)

Abstract

Rotational structures have been measured using the Jurogam II and GAMMASPHERE arrays at low spin following the ¹⁵⁵Gd(α,2n)¹⁵⁷Dy and ¹⁴⁸Nd(¹²C,5n)¹⁵⁵Dy reactions at 25 and 65 MeV, respectively. We report high-K bands, which are conjectured to be the first candidates of a Kπ=2⁺γ vibrational band, built on the [505]11/2⁻ neutron orbital, in both odd-A155,157Dy isotopes. The coupling of the first excited K=0⁺ states or the so-called β vibrational bands at 661 and 676 keV in ¹⁵⁴Dy and ¹⁵⁶Dy to the [505]11/2− orbital, to produce a Kπ=11/2⁻ band, was not observed in both ¹⁵⁵Dy and ¹⁵⁷Dy, respectively. The implication of these findings on the interpretation of the first excited 0⁺ states in the core nuclei ¹⁵⁴Dy and ¹⁵⁶Dy are also discussed.

Published
2020

7. α-spectroscopy studies of the new nuclides ¹⁶⁵Pt and ¹⁷⁰Hg

Author

Hilton, J. (J.), Uusitalo, J. (J.), Saren, J. (J.), Page, R. D. (R. D.), Joss, D. T. (D. T.), AlAqeel, M. A. (M. A. M.), Badran, H. (H.), Briscoe, A. D. (A. D.), Calverley, T. (T.), Cox, D. M. (D. M.), Grahn, T. (T.), Gredley, A. (A.), Greenlees, P. T. (P. T.), Harding, R. (R.), Herzan, A. (A.), Higgins, I. E. (I. E.), Julin, R. (R.), Juutinen, S. (S.), Konki, J. (J.), Labiche, M. (M.), Leino, M. (M.), Lewis, M. C. (M. C.), Ojala, J. (J.), Pakarinen, J. (J.), Papadakis, P. (P.), Partanen, J. (J.), Rahkila, P. (P.), Ruotsalainen, P. (P.), Sandzelius, M. (M.), Scholey, C. (C.), Sorri, J. (J.), Sottili, L. (L.), Stolze, S. (S.), and Wearing, F. (F.)

Subjects
High Energy Physics::Experiment, Nuclear Experiment
Abstract

The new nuclides \(^{165}\mathrm{Pt}\) and \(^{170}\mathrm{Hg}\) were produced in the reactions \(^{92}\mathrm{Mo}(^{78}\mathrm{Kr},5n)\) and \(^{96}\mathrm{Ru}(^{78}\mathrm{Kr},4n)\) at bombarding energies of 418 MeV and 390 MeV, respectively. For \(^{170}\mathrm{Hg}\) an α-particle energy of \(E_{α} = 7590(30)\) keV and half-life of \(t_{1/2} = 0.08^{+0.40}_{−0.04}\)ms were deduced, while for \(^{165}\mathrm{Pt}\) the corresponding values were 7272(14) keV and \(0.26^{+0.26}_{−0.09}\)ms. Comparison of the reduced α-decay widths with systematics indicates that both α decays are unhindered. Although combining the measured α-decay Q values with extrapolated masses suggests that both new nuclides are unbound to two-proton emission by more than 1 MeV, their α-decay half-lives are too short for this decay mode to compete. Improved data were also obtained for \(^{166,167}\mathrm{Pt}\), produced via the \(^{96}\mathrm{Ru}(^{78}\mathrm{Kr},α4n)\) and \(^{96}\mathrm{Ru}(^{78}\mathrm{Kr},α3n)\) reactions at bombarding energies of 390 MeV and 418 MeV.

Published
2019

8. Shape coexistence in ¹⁷⁸Hg

Author

Mueller-Gatermann, C. (C.), Dewald, A. (A.), Fransen, C. (C.), Auranen, K. (K.), Badran, H. (H.), Beckers, M. (M.), Blazhev, A. (A.), Braunroth, T. (T.), Cullen, D. M. (D. M.), Fruet, G. (G.), Goldkuhle, A. (A.), Grahn, T. (T.), Greenlees, P. T. (P. T.), Herzan, A. (A.), Jakobsson, U. (U.), Jenkins, D. (D.), Jolie, J. (J.), Julin, R. (R.), Juutinen, S. (S.), Konki, J. (J.), Leino, M. (M.), Litzinger, J. (J.), Nomura, K. (K.), Pakarinen, J. (J.), Peura, P. (P.), Procter, M. G. (M. G.), Rahkila, P. (P.), Ruotsalainen, P. (P.), Sandzelius, M. (M.), Saren, J. (J.), Scholey, C. (C.), Sorri, J. (J.), Stolze, S. (S.), Taylor, M. J. (M. J.), Uusitalo, J. (J.), Zell, K. O. (K. O.), Mueller-Gatermann, C. (C.), Dewald, A. (A.), Fransen, C. (C.), Auranen, K. (K.), Badran, H. (H.), Beckers, M. (M.), Blazhev, A. (A.), Braunroth, T. (T.), Cullen, D. M. (D. M.), Fruet, G. (G.), Goldkuhle, A. (A.), Grahn, T. (T.), Greenlees, P. T. (P. T.), Herzan, A. (A.), Jakobsson, U. (U.), Jenkins, D. (D.), Jolie, J. (J.), Julin, R. (R.), Juutinen, S. (S.), Konki, J. (J.), Leino, M. (M.), Litzinger, J. (J.), Nomura, K. (K.), Pakarinen, J. (J.), Peura, P. (P.), Procter, M. G. (M. G.), Rahkila, P. (P.), Ruotsalainen, P. (P.), Sandzelius, M. (M.), Saren, J. (J.), Scholey, C. (C.), Sorri, J. (J.), Stolze, S. (S.), Taylor, M. J. (M. J.), Uusitalo, J. (J.), and Zell, K. O. (K. O.)

Abstract

Lifetime measurements of excited states in ¹⁷⁸Hg have been performed using the ¹⁰³Rh(⁷⁸Kr,p2n) reaction at a beam energy of 354 MeV. The recoil-decay tagging (RDT) technique was applied to select the ¹⁷⁸Hg nuclei and associate the prompt γ rays with the correlated characteristic ground-state α decay. Lifetimes of the four lowest yrast states of ¹⁷⁸Hg have been determined using the recoil distance Doppler-shift (RDDS) method. The experimental data are compared to theoretical predictions with focus on shape coexistence. The results confirm the shift of the deformed prolate structures to higher lying states but also indicate their increasing deformation with decreasing neutron number.

Published
2019

9. Prompt and delayed spectroscopy of ²⁰³At:observation of a shears band and a 29/2+ isomeric state

Author

Auranen, K. (K.), Uusitalo, J. (J.), Juutinen, S. (S.), Badran, H. (H.), Bisso, F. D. (F. Defranchi), Cox, D. (D.), Grahn, T. (T.), Greenlees, P. T. (P. T.), Herzáň, A. (A.), Jakobsson, U. (U.), Julin, R. (R.), Konki, J. (J.), Leino, M. (M.), Lightfoot, A. (A.), Mallaburn, M. J. (M. J.), Neuvonen, O. (O.), Pakarinen, J. (J.), Papadakis, P. (P.), Partanen, J. (J.), Rahkila, P. (P.), Sandzelius, M. (M.), Sarén, J. (J.), Scholey, C. (C.), Sorri, J. (J.), Stolze, S. (S.), and Wang, Y. K. (Y. K.)

Subjects
Nuclear Experiment
Abstract

Using fusion-evaporation reactions, a gas-filled recoil separator, recoil-gating technique and recoil-isomer decay tagging technique we have extended the level scheme of ²⁰³At (N = 118) significantly. We have observed an isomeric [τ=14.1(3)μs] state with a spin and parity of 29/2+. The isomeric state is suggested to originate from the π(h9/2)⊗∣∣²⁰²Po;11⁻⟩ coupling, and it is depopulated through 286 keV E2 and 366 keV E3 transitions. In addition, we have observed a cascade of magnetic-dipole transitions which is suggested to be generated by the shears mechanism.

Published
2018

10. Level structure above the 17⁺ isomeric state in ¹⁵²₆₉Tm₈₃

Author

Singh, B. S. (B. S. Nara), Cullen, D. M. (D. M.), Taylor, M. J. (M. J.), Srivastava, P. C. (P. C.), Isacker, P. V. (P. Van), Beeke, O. (O.), Dodson, B. (B.), Scholey, C. (C.), O’Donell, D. (D.), Jakobson, U. (U.), Grahn, T. (T.), Greenlees, P. T. (P. T.), Jones, P. M. (P. M.), Julin, R. (R.), Khan, S. (S.), Leino, M. (M.), Leppänen, A.-P. (A.-P.), Eeckhaudt, S. (S.), Mäntyniemi, K. (K.), Pakarinen, J. (J.), Peura, P. (P.), Rahkila, P. (P.), Sarén, J. (J.), Sorri, J. (J.), Uusitalo, J. (J.), and Venhart, M. (M.)

Subjects
Shell model, Electromagnetic transitions, Lifetimes & widths, Nuclear forces, Nuclear Theory, Nuclear Experiment, Isomer decays, Nuclear spin & parity
Abstract

Excited states above the 17⁺ isomeric state in the proton-rich nucleus ¹⁵²Tm were established by employing the recoil-isomer tagging technique. Data were collected using the JUROGAM gamma-ray array and the GREAT spectrometer together with the recoil ion transport unit (RITU) gas-filled recoil separator and analyzed to identify the prompt and delayed γ decays from the levels in ¹⁵²Tm. Shell-model calculations, either in a large valence space or in a reduced model space with five protons in the π0h₁₁/₂ orbital and one neutron in the ν1f₇/₂ orbital, agree with the observed energies of the yrast levels up to angular momentum J = 21. The observation of near degeneracies in the energy spectrum can be attributed to specific components of the proton-neutron interaction. The isomeric decay of the 17⁺ level is not reproduced in the shell-model calculations as it arises from a delicate balance between hindrance due to seniority selection rules and enhancement due to configuration mixing.

Published
2018

11. Evolution from γ-soft to stable triaxiality in ¹³⁶Nd as a prerequisite of chirality

Author

Lv, B. F. (B. F.), Petrache, C. M. (C. M.), Astier, A. (A.), Dupont, E. (E.), Lopez-Martens, A. (A.), Greenlees, P. T. (P. T.), Badran, H. (H.), Calverley, T. (T.), Cox, D. M. (D. M.), Grahn, T. (T.), Hilton, J. (J.), Julin, R. (R.), Juutinen, S. (S.), Konki, J. (J.), Leino, M. (M.), Pakarinen, J. (J.), Papadakis, P. (P.), Partanen, J. (J.), Rahkila, P. (P.), Sandzelius, M. (M.), Saren, J. (J.), Scholey, C. (C.), Sorri, J. (J.), Stolze, S. (S.), Uusitalo, J. (J.), Herzan, A. (A.), Cederwall, B. (B.), Ertoprak, A. (A.), Liu, H. (H.), Guo, S. (S.), Liu, M. L. (M. L.), Qiang, Y. H. (Y. H.), Wang, J. G. (J. G.), Zhou, X. H. (X. H.), Kuti, I. (I), Timar, J. (J.), Tucholski, A. (A.), Srebrny, J. (J.), and Andreoiu, C. (C.)

Abstract

The level structure of ¹³⁶Nd has been investigated using the ¹⁰⁰Mo(⁴⁰Ar, 4n) reaction and the JUROGAM II+RITU+GREAT setup. The level scheme has been extended significantly. Many new bands have been identified both at low and high spin, among which are five nearly degenerate bands interpreted as chiral partners. Excitation energies, spins, and parities of the previously known bands are revised and firmly established, and some previously known bands have been revised. Configurations are assigned to the observed bands based on cranked Nilsson-Strutinsky calculations. The band structure of ¹³⁶Nd is now clarified and the various types of single-particle and collective excitations are well understood.

Published
2018

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