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Petrache, C. M., Lv, B. F., Astier, A., Dupont, E., Wang, Y. K., Zhang, S. Q., . . . Andreoiu, C. (2018). Evidence of chiral bands in even-even nuclei. Physical Review C: Covering Nuclear Physics, 97(4), Article ID 041304.
Open this publication in new window or tab >>Evidence of chiral bands in even-even nuclei
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2018 (English)In: Physical Review C: Covering Nuclear Physics, ISSN 2469-9985, E-ISSN 2469-9993, Vol. 97, no 4, article id 041304Article in journal (Refereed) Published
Abstract [en]

Evidence for chiral doublet bands has been observed for the first time in the even-even nucleus Nd136. One chiral band was firmly established. Four other candidates for chiral bands were also identified, which can contribute to the realization of the multiple pairs of chiral doublet bands (MχD) phenomenon. The observed bands are investigated by the constrained and tilted axis cranking covariant density functional theory (TAC-CDFT). Possible configurations have been explored. The experimental energy spectra, angular momenta, and B(M1)/B(E2) values for the assigned configurations are globally reproduced by TAC-CDFT. Calculated results support the chiral interpretation of the observed bands, which correspond to shapes with maximum triaxiality induced by different multiquasiparticle configurations in Nd136.

Place, publisher, year, edition, pages
American Physical Society, 2018
National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-229638 (URN)10.1103/PhysRevC.97.041304 (DOI)000431992700001 ()2-s2.0-85046626065 (Scopus ID)
Funder
Swedish Research Council, 621-2014-5558EU, FP7, Seventh Framework Programme, 262010 (ENSAR)
Note

QC 20180605

Available from: 2018-06-05 Created: 2018-06-05 Last updated: 2018-06-05Bibliographically approved
Ertoprak, A., Cederwall, B., Qi, C., Doncel, M., Jakobsson, U., Nyako, B. M., . . . Xiao, Z. G. (2018). M1 and E2 transition rates from core-excited states in semi-magic Ru-94. European Physical Journal A, 54(9), Article ID 145.
Open this publication in new window or tab >>M1 and E2 transition rates from core-excited states in semi-magic Ru-94
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2018 (English)In: European Physical Journal A, ISSN 1434-6001, E-ISSN 1434-601X, Vol. 54, no 9, article id 145Article in journal (Refereed) Published
Abstract [en]

Lifetimes of high-spin states have been measured in the semi-magic (N = 50) nucleus Ru-94. Excited states in Ru-94 were populated in the Ni-58(Ca-40, 4p)Ru-94* fusion-evaporation reaction at the Grand Accelerateur National d'Ions Lourds (GANIL) accelerator complex. DSAM lifetime analysis was performed on the Doppler broadened line shapes in energy spectra obtained from gamma-rays emitted while the residual nuclei were slowing down in a thick 6 mg/cm(2) metallic Ni-58 target. In total eight excited-state lifetimes in the angular momentum range I = (13-20)h have been measured, five of which were determined for the first time. The corresponding B(M1) and B(E2) reduced transition strengths are discussed within the framework of large-scale shell model calculations to study the contribution of different particle-hole configurations, in particular for analyzing contributions from core-excited configurations.

Place, publisher, year, edition, pages
Springer, 2018
National Category
Subatomic Physics
Identifiers
urn:nbn:se:kth:diva-234570 (URN)10.1140/epja/i2018-12581-7 (DOI)000443091000003 ()2-s2.0-85052645166 (Scopus ID)
Funder
Swedish Research Council, 621-2014-5558Swedish Research Council, 621-2012-3805Swedish Research Council, 621-2013-4323Göran Gustafsson Foundation for Research in Natural Sciences and Medicine
Note

QC 20180917

Available from: 2018-09-19 Created: 2018-09-19 Last updated: 2018-09-19Bibliographically approved
Boso, A., Lenzi, S. M., Recchia, F., Bonnard, J., Zuker, A. P., Aydin, S., . . . Valiente-Dobon, J. J. (2018). Neutron Skin Effects in Mirror Energy Differences: The Case of Mg-23-Na-23. Physical Review Letters, 121(3), Article ID 032502.
Open this publication in new window or tab >>Neutron Skin Effects in Mirror Energy Differences: The Case of Mg-23-Na-23
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2018 (English)In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 121, no 3, article id 032502Article in journal (Refereed) Published
Abstract [en]

Energy differences between analogue states in the T = 1/2 Mg-23-Na-23 mirror nuclei have been measured along the rotational yrast bands. This allows us to search for effects arising from isospin-symmetrybreaking interactions (ISB) and/or shape changes. Data are interpreted in the shell model framework following the method successfully applied to nuclei in the f(7/2) shell. It is shown that the introduction of a schematic ISB interaction of the same type of that used in the f(7/2) shell is needed to reproduce the data. An alternative novel description, applied here for the first time, relies on the use of an effective interaction deduced from a realistic charge-dependent chiral nucleon-nucleon potential. This analysis provides two important results: (i) The mirror energy differences give direct insight into the nuclear skin; (ii) the skin changes along the rotational bands are strongly correlated with the difference between the neutron and proton occupations of the s(1/2) "halo" orbit.

Place, publisher, year, edition, pages
American Physical Society, 2018
National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-232764 (URN)10.1103/PhysRevLett.121.032502 (DOI)000439286800004 ()2-s2.0-85050384281 (Scopus ID)
Note

QC 20180807

Available from: 2018-08-07 Created: 2018-08-07 Last updated: 2018-08-07Bibliographically approved
Litzinger, J., Blazhev, A., Dewald, A., Didierjean, F., Duchene, G., Fransen, C., . . . Vogt, A. (2018). Transition probabilities in neutron-rich Se-80,Se-82 and the role of the nu g(9/2) orbital. Physical Review C: Covering Nuclear Physics, 97(4), Article ID 044323.
Open this publication in new window or tab >>Transition probabilities in neutron-rich Se-80,Se-82 and the role of the nu g(9/2) orbital
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2018 (English)In: Physical Review C: Covering Nuclear Physics, ISSN 2469-9985, E-ISSN 2469-9993, Vol. 97, no 4, article id 044323Article in journal (Refereed) Published
Abstract [en]

Transition probabilities of intermediate-spin yrast and non-yrast excitations in Se-80,Se-82 were investigated in a recoil distance Doppler-shift (RDDS) experiment performed at the Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Legnaro. The Cologne Plunger device for deep inelastic scattering was used for the RDDS technique and was combined with the AGATA Demonstrator array for the gamma-ray detection and coupled to the PRISMA magnetic spectrometer for an event-by-event particle identification. In Se-80, the level lifetimes of the yrast (6(1)(+)) and (8(1)(+)) states and of a non-yrast band feeding the yrast 4(1)(+) state are determined. A spin and parity assignment of the head of this sideband is discussed based on the experimental results and supported by large-scale shell-model calculations. In Se-82, the level lifetimes of the yrast 6(1)(+) state and the yrare 4(2)(+) state and lifetime limits of the yrast (10(1)(+)) state and of the 5(1)(-) state are determined. Although the experimental results contain large uncertainties, they are interpreted with care in terms of large-scale shell-model calculations using the effective interactions JUN45 and jj44b. The excited states' wave functions are investigated and discussed with respect to the role of the neutron g(9/2) orbital.

Place, publisher, year, edition, pages
American Physical Society, 2018
National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-230544 (URN)10.1103/PhysRevC.97.044323 (DOI)000431992700002 ()2-s2.0-85046622604 (Scopus ID)
Note

QC 20180723

Available from: 2018-07-23 Created: 2018-07-23 Last updated: 2018-07-23Bibliographically approved
Jentschel, M., Blanc, A., de France, G., Koster, U., Leoni, S., Mutti, P., . . . Zielinska, M. (2017). EXILL - a high-efficiency, high-resolution setup for gamma-spectroscopy at an intense cold neutron beam facility. Journal of Instrumentation, 12, Article ID P11003.
Open this publication in new window or tab >>EXILL - a high-efficiency, high-resolution setup for gamma-spectroscopy at an intense cold neutron beam facility
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2017 (English)In: Journal of Instrumentation, ISSN 1748-0221, E-ISSN 1748-0221, Vol. 12, article id P11003Article in journal (Refereed) Published
Abstract [en]

In the EXILL campaign a highly efficient array of high purity germanium (HPGe) detectors was operated at the cold neutron beam facility PF1B of the Institut Laue-Langevin (ILL) to carry out nuclear structure studies, via measurements of gamma-rays following neutron-induced capture and fission reactions. The setup consisted of a collimation system producing a pencil beam with a thermal capture equivalent flux of about 10(8) ns(-1)cm(2) at the target position and negligible neutron halo. The targetwas surrounded by an array of eight to ten anti-Compton shielded EXOGAMClover detectors, four to six anti-Compton shielded large coaxial GASP detectors and two standard Clover detectors. For a part of the campaign the array was combined with 16 LaBr3:(Ce) detectors from the FATIMA collaboration. The detectorswere arranged in an array of rhombicuboctahedron geometry, providing the possibility to carry out very precise angular correlation and directional-polarization correlation measurements. The triggerless acquisition system allowed a signal collection rate of up to 6 x 10(5) Hz. The data allowed to set multi-fold coincidences to obtain decay schemes and in combination with the FATIMA array of LaBr3:(Ce) detectors to analyze half-lives of excited levels in the pico-to microsecond range. Precise energy and efficiency calibrations of EXILL were performed using standard calibration sources of Ba-133, Co-60 and Eu-152 as well as data from the reactions Al-27(n, gamma)Al-28 and Cl-35(n,gamma)Cl-36 in the energy range from 30 keV up to 10MeV.

Place, publisher, year, edition, pages
IOP PUBLISHING LTD, 2017
Keywords
Instrumentation for neutron sources, Gamma detectors (scintillators, CZT, HPG, HgI etc), Spectrometers
National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-217938 (URN)10.1088/1748-0221/12/11/P11003 (DOI)000414625700003 ()
Note

QC 20171121

Available from: 2017-11-21 Created: 2017-11-21 Last updated: 2017-11-24Bibliographically approved
Singh, B., Erni, W., Krusche, B., Steinacher, M., Walford, N., Liu, H., . . . Semenov-Tian-Shansky, K. M. (2017). Feasibility study for the measurement of pi N transition distribution amplitudes at (P)over-barANDA in (P)over-barp -> J/psi pi(0). Physical Review D: covering particles, fields, gravitation, and cosmology, 95(3), Article ID 032003.
Open this publication in new window or tab >>Feasibility study for the measurement of pi N transition distribution amplitudes at (P)over-barANDA in (P)over-barp -> J/psi pi(0)
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2017 (English)In: Physical Review D: covering particles, fields, gravitation, and cosmology, ISSN 2470-0010, E-ISSN 2470-0029, Vol. 95, no 3, article id 032003Article in journal (Refereed) Published
Abstract [en]

The exclusive charmonium production process in (P) over barp annihilation with an associated pi 0 meson (p) over barp -> J/psi pi(0) is studied in the framework of QCD collinear factorization. The feasibility of measuring this reaction through the J/psi -> e(+) e(-) decay channel with the AntiProton ANnihilation at DArmstadt ((P) over bar ANDA) experiment is investigated. Simulations on signal reconstruction efficiency as well as the background rejection from various sources including the (P) over barp -> pi(+)pi(-)pi(0) and (p) over barp -> J/psi pi(0)pi(0) reactions are performed with PANDAROOT, the simulation and analysis software framework of the (P) over bar ANDA experiment. It is shown that the measurement can be done at (P) over bar ANDA with significant constraining power under the assumption of an integrated luminosity attainable in four to five months of data taking at the maximum design luminosity.

National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-204693 (URN)10.1103/PhysRevD.95.032003 (DOI)000393744600003 ()2-s2.0-85021668121 (Scopus ID)
Funder
EU, FP7, Seventh Framework Programme, HP3 GA283286Swedish Research Council
Note

QC 20170602

Available from: 2017-06-02 Created: 2017-06-02 Last updated: 2017-11-29Bibliographically approved
Boso, A., Lenzi, S. M., Recchia, F., Bonnard, J., Aydin, S., Bentley, M. A., . . . Valiente-Dobon, J. J. (2017). ISOSPIN SYMMETRY BREAKING IN MIRROR NUCLEI Mg-23-Na-23. Paper presented at Zakopane Conference on Nuclear Physics - Extremes of the Nuclear Landscape, AUG 28-SEP 04, 2016, Zakopane, POLAND. Acta Physica Polonica B, 48(3), 313-318
Open this publication in new window or tab >>ISOSPIN SYMMETRY BREAKING IN MIRROR NUCLEI Mg-23-Na-23
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2017 (English)In: Acta Physica Polonica B, ISSN 0587-4254, E-ISSN 1509-5770, Vol. 48, no 3, p. 313-318Article in journal (Refereed) Published
Abstract [en]

Mirror energy differences (MED) are a direct consequence of isospin symmetry breaking. Moreover, the study of MED has proved to give valuable information of several nuclear structure properties. We present the results of an experiment performed in GANIL to study the MED in mirror nuclei Mg-23-Na-23 up to high spin. The experimental values are compared with state-of-the-art shell model calculations. This permits to enlighten several nuclear structure properties, such as the way in which the nucleons alignment proceeds, the radius variation with J, the role of the spin-orbit interaction and the importance of isospin symmetry breaking terms of nuclear origin.

Place, publisher, year, edition, pages
Jagiellonian University Press, 2017
National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-206295 (URN)10.5506/APhysPolB.48.313 (DOI)000398717500011 ()
Conference
Zakopane Conference on Nuclear Physics - Extremes of the Nuclear Landscape, AUG 28-SEP 04, 2016, Zakopane, POLAND
Note

QC 20170508

Available from: 2017-05-08 Created: 2017-05-08 Last updated: 2017-05-08Bibliographically approved
Ralet, D., Bäck, T., Cederwall, B., Doncel, M., Ghazi Moradi, F., Zielinska, M. & et al., . (2017). Lifetime measurement of neutron-rich even-even molybdenum isotopes. Physical Review C: Covering Nuclear Physics, 95(3), Article ID 034320.
Open this publication in new window or tab >>Lifetime measurement of neutron-rich even-even molybdenum isotopes
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2017 (English)In: Physical Review C: Covering Nuclear Physics, ISSN 2469-9985, E-ISSN 2469-9993, Vol. 95, no 3, article id 034320Article in journal (Refereed) Published
Abstract [en]

Background: In the neutron-rich A approximate to 100 mass region, rapid shape changes as a function of nucleon number as well as coexistence of prolate, oblate, and triaxial shapes are predicted by various theoretical models. Lifetime measurements of excited levels in the molybdenum isotopes allow the determination of transitional quadrupole moments, which in turn provides structural information regarding the predicted shape change. Purpose: The present paper reports on the experimental setup, the method that allowed one to measure the lifetimes of excited states in even-even molybdenum isotopes from mass A = 100 up to mass A = 108, and the results that were obtained. Method: The isotopes of interest were populated by secondary knock-out reaction of neutron-rich nuclei separated and identified by the GSI fragment separator at relativistic beam energies and detected by the sensitive PreSPEC-AGATA experimental setup. The latter included the Lund-York-Cologne calorimeter for identification, tracking, and velocity measurement of ejectiles, and AGATA, an array of position sensitive segmented HPGe detectors, used to determine the interaction positions of the gamma ray enabling a precise Doppler correction. The lifetimes were determined with a relativistic version of the Doppler-shift-attenuation method using the systematic shift of the energy after Doppler correction of a gamma-ray transition with a known energy. This relativistic Doppler-shift-attenuation method allowed the determination of mean lifetimes from 2 to 250 ps. Results: Even-even molybdenum isotopes from mass A = 100 to A = 108 were studied. The decays of the low-lying states in the ground-state band were observed. In particular, two mean lifetimes were measured for the first time: tau = 29.7(-9.1)(+11.3) ps for the 4(+) state of Mo-108 and tau = 3.2(-0.7)(+ 0.7) ps for the 6(+) state of Mo-102. Conclusions: The reduced transition strengths B(E2), calculated from lifetimes measured in this experiment, compared to beyond-mean-field calculations, indicate a gradual shape transition in the chain of molybdenum isotopes when going from A = 100 to A = 108 with a maximum reached at N = 64. The transition probabilities decrease for Mo-108 which may be related to its well-pronounced triaxial shape indicated by the calculations.

Place, publisher, year, edition, pages
AMER PHYSICAL SOC, 2017
National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-207464 (URN)10.1103/PhysRevC.95.034320 (DOI)000399143200002 ()2-s2.0-85016484924 (Scopus ID)
Note

QC 20170519

Available from: 2017-05-19 Created: 2017-05-19 Last updated: 2017-11-29Bibliographically approved
Doncel, M., Cederwall, B., Qi, C., Li, H. J., Jakobsson, U., Auranen, K., . . . Uusitalo, J. (2017). Lifetime measurements of excited states in W-162 and W-164 and the evolution of collectivity in rare-earth nuclei. Physical Review C: Covering Nuclear Physics, 95(4), Article ID 044321.
Open this publication in new window or tab >>Lifetime measurements of excited states in W-162 and W-164 and the evolution of collectivity in rare-earth nuclei
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2017 (English)In: Physical Review C: Covering Nuclear Physics, ISSN 2469-9985, E-ISSN 2469-9993, Vol. 95, no 4, article id 044321Article in journal (Refereed) Published
Abstract [en]

Lifetimes of the first excited 2(+) states in the extremely neutron- deficient W-162 and W-164 nuclei have been measured using the recoil distance Doppler shift technique. Experimental B(E2) data for the isotopic chains of hafnium, tungsten, and osmium, from the midshell region near the beta-stability line towards the N = 82 closed shell and the most neutron-deficient nuclides, are compared with predictions of nuclear deformations and 2(1)(+) -> 0(g.s)(.+) reduced transition strengths from different classes of state-of-the-art theoretical model calculations. The results reveal striking differences and deficiencies in the predictive power of current nuclear structure models.

Place, publisher, year, edition, pages
American Physical Society, 2017
National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-207673 (URN)10.1103/PhysRevC.95.044321 (DOI)000400140500006 ()2-s2.0-85018532567 (Scopus ID)
Funder
Swedish Research Council, 621-2014-5558EU, FP7, Seventh Framework Programme, 262010 ENSAR
Note

QC 20170601

Available from: 2017-06-01 Created: 2017-06-01 Last updated: 2017-11-29Bibliographically approved
Ertoprak, A., Cederwall, B., Jakobsson, U., Nyako, B. M., Nyberg, J., Davies, P., . . . Xiao, Z. G. (2017). LIFETIME MEASUREMENTS WITH THE DOPPLER SHIFT ATTENUATION METHOD USING A THICK HOMOGENEOUS PRODUCTION TARGET - VERIFICATION OF THE METHOD. Paper presented at Zakopane Conference on Nuclear Physics - Extremes of the Nuclear Landscape, AUG 28-SEP 04, 2016, Zakopane, POLAND. Acta Physica Polonica B, 48(3), 325-329
Open this publication in new window or tab >>LIFETIME MEASUREMENTS WITH THE DOPPLER SHIFT ATTENUATION METHOD USING A THICK HOMOGENEOUS PRODUCTION TARGET - VERIFICATION OF THE METHOD
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2017 (English)In: Acta Physica Polonica B, ISSN 0587-4254, E-ISSN 1509-5770, Vol. 48, no 3, p. 325-329Article in journal (Refereed) Published
Abstract [en]

Doppler Shift Attenuation Method (DSAM) analysis of excited-state lifetimes normally employs thin production targets mounted on a thick stopper foil ("backing") serving to slow down and stop the recoiling nuclei of interest in a well-defined manner. Use of a thick, homogeneous production target leads to a more complex analysis as it results in a substantial decrease in the energy of the incident projectile which traverses the target with an associated change in the production cross section of the residues as a function of penetration depth. Here, a DSAM lifetime analysis using a thick homogeneous target has been verified using the Doppler broadened lineshapes of gamma rays following the decay of highly excited states in the semi-magic (N = 50) nucleus Ru-94. Lifetimes of excited states in the Ru-94 nucleus have been obtained using a modified version of the LINESHAPE package from the Doppler broadened lineshapes resulting from the emission of the gamma rays, while the residual nuclei were slowing down in the thick (6 mg/cm(2)) metallic Ni-58 target. The results have been validated by comparison with a previous measurement using a different (RDDS) technique.

Place, publisher, year, edition, pages
Jagiellonian University Press, 2017
National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-206296 (URN)10.5506/APhysPolB.48.325 (DOI)000398717500013 ()2-s2.0-85017146840 (Scopus ID)
Conference
Zakopane Conference on Nuclear Physics - Extremes of the Nuclear Landscape, AUG 28-SEP 04, 2016, Zakopane, POLAND
Note

QC 20170508

Available from: 2017-05-08 Created: 2017-05-08 Last updated: 2017-11-09Bibliographically approved
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ORCID iD: ORCID iD iconorcid.org/0000-0003-1771-2656

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