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We present the first triaxial beyond-mean-field study of the excitation spectra of even-even superheavy nuclei. As representative examples, we have chosen the members of the α-decay chains of 292Lv and 294Og, the heaviest even-even nuclei which have been synthesized so far using 48Ca-induced fusion-evaporation reactions. In our calculations, the effective finite-range density-dependent Gogny force is used and the angular-momentum and particle-number symmetries are restored. Configuration-mixing calculations are performed to determine ground- and excited-state deformations and to establish the collective band structures of these nuclei. Rapidly varying characteristics are predicted for the members of both decay chains, which are further accentuated when compared to the predictions of simple collective models. Based on the present calculations, the prospect of observing α-decay fine structures in future experiments is discussed

19 pags., 14 figs., 3 tabs., A γ-ray spectroscopic study of Po212 was performed at the Grand Accélérateur National d'Ions Lourds, using the inverse kinematics α-transfer reaction C12(Pb208,Po212)Be8 and the AGATA spectrometer. A careful analysis based on γγ coincidence relations allowed us to establish 14 new excited states in the energy range between 1.9 and 3.3 MeV. None of these states, however, can be considered as candidates for the levels with spins and parities of 1- and 2- and excitation energies below 2.1 MeV, which have been predicted by recent α-cluster model calculations. A systematic comparison of the experimentally established excitation scheme of Po212 with shell-model calculations was performed. This comparison suggests that the six states with excitation energies (spins and parities) of 1744 (4-), 1751 (8-), 1787 (6-), 1946 (4-), 1986 (8-), and 2016 (6-) keV, which previously were interpreted as α-cluster states, may in fact be of positive parity and belong to low-lying shell-model multiplets. This reinterpretation of the structure of Po212 is supported by experimental information with respect to the linear polarization of γ rays, which suggests a magnetic character of the 432-keV γ ray decaying from the state at an excitation energy of 1787 keV to the 61+ yrast state, and exclusive reaction cross sections., This project has received funding from the European Union’s Horizon 2020 research and innovation programme under Grant Agreement No. 654002 and FEDER funds. We furthermore acknowledge support from the Spanish Ministerio de Ciencia, Inovación y Universidades under contracts FPA2014-57196-C5, FPA2017-84756-C4, and SEV-2014-0398, the Generalitat Valenciana under Grant No. PROMETEO/2019/005, the Swedish Research Council (Vetenskapsrådet, VR 2016-3969), and the German BMBF under Contracts No. 05P18PKFN9 and No. 05P19PKFNA.

5 pags., 4 figs., The low-lying excited states in the neutron-deficient N=Z+1 nucleus Tc444387 have been studied via the fusion-evaporation reaction Fe54(Ar36, 2n1p)Tc87 at the Grand Accélérateur National d'Ions Lourds (GANIL), France. The AGATA spectrometer was used in conjunction with the auxiliary NEDA, Neutron Wall, and DIAMANT detector arrays to measure coincident prompt γ rays, neutrons, and charged particles emitted in the reaction. A level scheme of Tc87 from the (9/2g.s.+) state to the (33/21+) state was established based on six mutually coincident γ-ray transitions. The constructed level structure exhibits a rotational behavior with a sharp backbending at ω≈0.50 MeV. A decrease in alignment frequency and increase in alignment sharpness in the odd-mass isotonic chains around N=44 is proposed as an effect of the enhanced isoscalar neutron-proton interactions in odd-mass nuclei when approaching the N=Z line., This work was supported by the Swedish Research Council under Grants No. 621-2014-5558 and No. 2019-04880, the EU 7th Framework Programme, Integrating Activities Transnational Access, Project No. 262010 ENSAR, the UK STFC under Grants No. ST/L005727/1 and No. ST/P003885/1, the Polish National Science Centre, Grants No. 2017/25/B/ST2/01569, No. COPIN-INFN, No. COPIN-IN2P3, and No. COPIGAL projects, the National Research, Development and Innovation Fund of Hungary (Project No. K128947), the European Regional Development Fund (Contract No. GINOP-2.3.3-15-2016-00034), the Hungarian National Research, Development and Innovation Office - NKFIH, Contract No. PD124717, the Ministerio de Ciencia e Innovación and Generalitat Valenciana, Spanish, under Grants No. SEV-2014-0398, No. FPA2017-84756-C4, and No. PROMETEO/2019/005 and by the EU FEDER funds. X.L. gratefully acknowledges support from the China Scholarship Council, Grant No. 201700260183 for his stay in Sweden.

(c) Consejo Superior de Investigaciones Científicas Licencia Creative Commons 3.0 España (by-nc), Presentamos un estudio de la situación de las científicas del área de Ciencia y Tecnologías Físicas en el CSIC, El estudio incluye datos numéricos en cuanto a presencia porcentual de mujeres en las distintas escalas y comisiones de evaluación, así como testimonios personales, reflexiones y consideraciones generales. Se pone de manifiesto el bajo porcentaje de investigadoras en esta Área, Se concluye el estudio con una serie de recomendaciones.

Linear polarization measurements have been performed for gamma rays in Ru-91 produced with the Ni-58(Ar-36,2p1n gamma)Ru-91 reaction at a beam energy of 111 MeV. The EXOGAM Ge clover array has been used to measure the gamma-gamma coincidences, gamma-ray linear polarization, and gamma-ray angular distributions. The polarization sensitivity of the EXOGAM clover detectors acting as Compton polarimeters has been determined in the energy range 0.3-1.3 MeV. Several transitions have been observed for the first time. Measurements of linear polarization and angular distribution have led to the firm assignments of spin differences and parity of high-spin states in Ru-91. More specifically, calculations using a semiempirical shell model were performed to understand the structures of the first and second (21/2(+)) and (17/2(+)) levels. The results are in good agreement with the experimental data, supporting the interpretation of the nonyrast (21/2(+)) and (17/2(+)) states in terms of the J(max) and J(max) - 2 members of the seniority-three nu(g(9/2))(-3) multiplet., The authors would like to thank the operators of the GANIL cyclotrons for providing the 36Ar beam. We would also like to thank the EXOGAM Collaboration for use of the clover Ge detector array, the DIAMANT Collaboration for use of the charged particle detector system, and the European gamma-ray Spectroscopy Pool for use of the neutron detector system. We acknowledge funding support from the French-Polish LEA COPIGAL and the IN2P3-Polish laboratories COPIN Agreement No. 06-122, from the UK STFC, from the Swedish Research Council (Contracts No. 2007-4067 and No. 2008-5793), from the Goran Gustafsson Foundation, from the OTKA under Contract No. K100835, and from the Bolyai Janos Foundation. AG has been supported by the Generalitat Valenciana, Spain, under Grant No. PROMETEO/2010/101 and by MINECO, Spain, under Grants No. AIC-D-2011-0746 and No. FPA2011-29854. AJ acknowledge financial support from the Spanish Ministerio de Ciencia e Innovacion under Contract No. FPA2011-29854-C04. ZY acknowledges the support from the Chinese Academy of Sciences, China.

The high-velocity transient-field (HVTF) technique was used to measure the g factor of the 2+ state of 72Zn produced as a radioactive beam. The transient-field strength was probed at high velocity in ferromagnetic iron and gadolinium hosts using 76Ge beams. The potential of the HVTF method is demonstrated and the difficulties that need to be overcome for a reliable use of the TF technique with high-Z, high-velocity radioactive beams are revealed. The polarization of K-shell vacancies at high velocity, which shows more than an order of magnitude difference between Z=20 and Z=30 is discussed. The g-factor measurement hints at the theoretically predicted transition in the structure of the Zn isotopes near N=40. ©2012 American Physical Society, This work was supported by the EU FP6 contract no. EURONS N◦RII3-CT-2004-506065, by the IAP Program, P6/23 BriX, Belgian Science Policy, by the Bulgarian Science Fund DID-02/16 and DFNR-02/5, by the Spanish Ministerio de Ciencia e Innovación under contract nos. FPA2007-66069 and FPA2009-13377-C02-02, the Spanish Consolider-Ingenio 2010 Programme CPAN (CSD2007-00042), and by the AustralianResearch Council Discovery Grant No. DP0773273.The work of E.F. has been supported in part by the ExtreMe Matter Institute EMMI.

Isomeric states in the semimagic 128-130Sn isotopes were populated in the fragmentation of a Xe136 beam on a Be9 target at an energy of 750 A•MeV. The decay of an isomeric state in Sn128 at an excitation energy of 4098 keV has been observed. Its half live has been determined to be T 1/2=220(30) ns from the time distributions of the delayed γ rays emitted in its decay. γγ coincidence relations were analyzed in order to establish the decay pattern of the newly established state toward the known (7-) and (10+) isomers at excitation energies of 2092 and 2492 keV, respectively. Based on a comparison with results of state-of-the-art shell-model calculations the new isomeric state is proposed to have the νh11/2-3d3/2-1 configuration with the four neutron holes in Sn132 maximally aligned to a total spin of Iπ=15-. © 2011 American Physical Society., We acknowledge financial support from the Spanish Ministerio de Ciencia e Innovacion under Contracts No. ´ FPA2007-66069 and No. FPA2009-13377-C02-02, the Spanish Consolider-Ingenio 2010 Programme CPAN (CSD2007- 00042), the German Federal Ministry of Education and Research (06KY205I), the Swedish Science Council, STFC/EPSRC (UK), the Polish Ministry of Science and Higher Education (N N202 309135), and the EU Access to Large Scale Facilities Programme (EURONS, EU Contract No. 506065).

The g factors of the first excited 2+ states in the 112 ,114,116,122,124Sn isotopes have been measured with high accuracy using the transient field technique in combination with Coulomb excitation in inverse kinematics. The experimental results are discussed in a qualitative way on the basis of empirical single-particle g factors of the relevant proton and neutron orbitals and are compared to a number of different theoretical calculations. The results are found to be best described by shell-model calculations in an extended configuration space. Clear evidence for the contribution of neutron pair excitations from the 1d3/2 to the 0h11/2 orbital to the wave function of the 21+ state in 122,124Sn has been obtained. © 2011 American Physical Society., This work has been supported by the Spanish Ministerio de Ciencia e Innovacion under Contracts No. FPA2007-66069 and No. FPA2009-13377-C02-02, the Spanish ConsoliderIngenio 2010 Programme CPAN (Contract No. CSD2007- 00042), and the German BMBF under Grant No. 06DA214I.

The relativistic projectile fragmentation of a 750 MeV per nucleon beam of Ag107 was used to populate isomeric states in neutron-deficient nuclei around A=80-90. Reaction products were separated and unambiguously identified using the GSI FRagment Separator (FRS) and its ancillary detectors. At the final focal plane, the fragments were slowed from relativistic energies by means of an aluminium degrader and implanted in a passive stopper in the center of the high-efficiency, high-granularity Stopped Rare Isotope Spectroscopic INvestigation at GSI (RISING) germanium array. This allowed the identification of excited states in the N=Z nuclei 4386Tc and, for the first time, 4182Nb. Isomeric states have also been identified for the first time in Tc87,88, and a previously unreported isomer was observed in Nb84. Experimental results are presented along with a discussion on the structure of these nuclei based on interpretations provided by several theoretical models. © 2009 The American Physical Society., Sponsored by the EPSRC (UK) and STFC (UK), The Swedish Research Council, The Polish Ministry of Science and Higher Education (Grant Nos. P03B03030 and N N202 309135), the Bulgarian Science Fund VUF06/05, the US Department of Energy (Grant Nos. DE-FG02-91ER-40609 and DE-AC02-06CH11357), the Spanish Ministerio de Educación y Ciencia (Project Nos. FPA2005-00696 and FPA2007-66069), the German Federal Ministry of Education, the Hungarian Scientific Research Fund (Contract No. K68801), research under Grant No. 06KY205I, and EURONS (European Commision Contract No. 506065). Chinese Major State Basic Development Program through Grant No. 2007CB815005 and the Natural Science Foundation of China under Contract No. 10875077.Nexia Solutions Ltd, a subsidiary of BNFL, for financial support.

17 pages, 9 figures, 6 tables.-- PACS nrs.: 21.10.Tg; 21.10.Re; 21.10.Ky; 27.90.+b., Lifetimes of excited states in 229Th, populated in the β decay of 229Ac, have been measured using the advanced time-delayed βγ γ (t) method. Half-lives of 14 states have been determined including 11 of them for the first time. Twenty-seven new γ lines have been introduced into the β-decay scheme of 229Ac based on results of γγ coincidence measurements. Reduced transition probabilities have been determined for more than 70 γ transitions in 229Th. Average |D0| values of 0.029(1), 0.077(3), and 0.024(5) e fm have been deduced for the lowest Kπ =1/2±, 3/2±, and 5/2± parity partner bands, respectively. Excited states in 229Th and experimental transition rates have been interpreted within the quasiparticle-plus-phonon model. The half-life of the 3.5-eV, 3/2+ isomeric state is predicted to be about 10 h. Potential energy surfaces on the (β2, β3) plane for the lowest single quasiparticle configurations in 229Th have been calculated using the Strutinsky method., This work has been supported in part by Grant No. 1 P03B 059 27 from the Polish Committee for Scientific Research(KBN) (for theoretical calculations), the Swedish Research Council, the research plan MSM0021620834 provided by the Ministry of Education of the Czech Republic, and the Spanish CICYT under Project No. FPA2002-04181-C04-02. Support by the European Commission through the HPRI-CT-1999-00018 project and by the ISOLDE Collaboration are also acknowledged. Fast timing detectors and electronics have been provided by the Fast Timing Pool of Electronics. One of us (E.R.) would like to thank the OSIRIS group for its generous hospitality and for financial support during her stay in Studsvik.

A total absorption spectrometer, dedicated to the study of very short-lived atomic species, has been built and installed at the CERN/ISOLDE mass separator. The beta decay of the neutron-deficient Kr-74 nucleus has been studied using this new device. The Gamow-Teller strength distribution has been observed over most of the Q(EC) window, and a total strength of 0.69(3) g(A)(2)/4pi has been measured for states with excitation energy below 3 MeV. Shape mixing in the Kr-74 ground state is inferred from a comparison of the experimental strength distribution with self-consistent, deformed, quasiparticle-random-phase-approximation calculations.

A novel method of deducing the deformation of the N=Z nucleus 76Sr is presented. It is based on the comparison of the experimental Gamow-Teller strength distribution B(GT) from its beta decay with the results of QRPA calculations. This method confirms previous indications of the strong prolate deformation of this nucleus in a totally independent way. The measurement has been carried out with a large Total Absorption gamma Spectrometer, 'Lucrecia', newly installed at CERN-ISOLDE.

18 págs.; 17 figs.; 3 tabs. ; PACS number(s): 23.20.Lv, 23.20.En, 27.70.1q, 21.60.Cs, The incomplete fusion reactions 7Li→158,160Gd at beam energies of 8 MeV/nucleon have been used to study the first band crossing region in the heavy stable Dy isotopes 160,162Dy. The γ rays were detected in the GASP spectrometer in coincidence with fast charged particles detected in the ISIS silicon ball. We succeeded to observe the first backbending in 162Dy at a crossing frequency of ℏ ω ≈ 350 keV, a value much higher than expected from other nuclei in this mass region. Moreover, for the first time in a nucleus with a very large interaction strength, the yrare band in 160Dy could be established up to rather high spin (I= 20ℏ) allowing for a precise determination of the interaction strength between the ground state and the Stockholm band, |Vg-S| = 219(2) keV. Together with |Vg-S| = 14(2) kev determined for the corresponding interaction in 162Dy, a full oscillation of the strengths from one node to the next could be observed within an isotopic chain. In addition to the ground state and Stockholm bands, many other known bands in the two nuclei were considerably extended to higher spin and the experimental results are compared to calculations within the projected shell model. ©2002 The American Physical Society, This work has been supported by Deutsches Bundesministerium fur Bildung, Wissenschaft, Forschung und Technologie (BMBF). A.J. acknowledges support by the Deutsche Forschungsgemeinschaft (DFG).

Tesis doctoral inédita leída en la Universidad Autónoma de Madrid, Facultad de Ciencias, Departamento de Física Teórica. Fecha de lectura: 28-10-2021

Tesis doctoral inédita leída en la Universidad Autónoma de Madrid, Facultad de Ciencias, Departamento de Física Teórica. Fecha de lectura: 16-11-2018, This thesis is focussed on the region around the doubly magic nucleus 132Sn (Z=50 and N=82). The nuclei situated in this region of the nuclear chart are of great interest both for nuclear structure investigations and nuclear astrophysics. By studying these systems, information about the evolution of nucleon-nucleon correlations, quadrupole collectivity and single-particle energies can be obtained. New experimental information allows the test of different nuclear models and examine their validity in this region of the nuclear chart. In order to study the neutron-rich nuclei located in the vicinity of 132Sn, in April 2015 an experiment was carried out at the Radioactive Isotope Beam Factory at the RIKEN Nishina Center, Japan. The radioactive beam was produced by the in-flight abrasion fission of a primary beam of 238U at 345 MeV/u bombarding a 4-mm-thick beryllium target. The exotic nuclei to be investigated were selected and identified using the BigRIPS in-flight separator. After the selection and identification, the neutron-rich radioactive isotopes were transported to the focal point, F8, where they impinged on two different reaction targets of carbon and gold. Surrounding these targets was the DALI2 spectrometer, which was used to detect the rays emitted by the decay of excited states in several N=82-84, Z 50 isotopes. Finally, the reaction products exited the target and were identified by the ZeroDegree spectrometer. The reduced transition probability B(E2; 0+1 ! 2+1 ) for the first excited 2+ state of the neutronrich 136Te nucleus, with two protons and two neutrons outside the 132Sn core, was determined via Coulomb excitation in inverse kinematics at intermediate energies. A value of B(E2) = 0.191(26) e2b2 was extracted from measured differential cross sections on gold and carbon targets in order to take into account both the Coulomb and the nuclear excitation contributions. Our experimental B(E2) value is compared to the previous values from literature and to different theoretical calculations. In addition, 133Sn was studied via the one-neutron knockout from a 134Sn projectile. Besides the known rays emitted from the decay of the single-particle states, additional -ray strength was observed above the neutron separation energy, extending up to about 5.5 MeV. These excited states are interpreted as neutron-hole states that are populated through the removal of a neutron from the closed N=50-82 shell of the 134Sn projectile. The ability of -ray emission to compete with neutron decay is explained taking into account the structure of the initial and final states, and the resultant wave-function overlap. Lastly, experimental inclusive cross sections for the multiple knockout of neutrons and protons were derived from different projectiles at energies around 165 MeV/u. The experimental values have been compared to predictions from state-of-the-art calculations based on a Monte Carlo description of the cascade and evaporation processes obtained with the INCL-ABLA reaction code

Tesis doctoral inédita. Universidad Autónoma de Madrid, Facultad de Ciencias, Departamento de Física Teórica. Fecha de Lectura