0000000001230983
AUTHOR
María José García Borge
showing 47 related works from this author
Proton dripline studies at ISOLDE: 31Ar and 9C
2002
In this contribution examples of the application of new technologies to disentangle the mechanism of $\beta$-delayed multiparticle emission are given. In particular the mechanism of $\beta$2p-emission from $^{31}$Ar has been resolved and proved to be sequential, a preview of $^{9}$C-decay data is discussed.
Search for forbidden?-decays of the drip line nucleus12Be
1994
Beta-coincidentγ-rays have been measured from implanted pure samples of12Be separated at the LISE3 spectrometer at GANIL. An intensity of 0.040(26) % can be estimated for the branching ratio of the isospin forbidden pure-Fermi transition to the 0+ excited state of12B and of 0.008(6)% of the transition to the 1−1 excited state. Both are taken to represent upper limits. The half-life has been re-measured to be 26.1(2.4) ms.
High-Statistics Sub-Barrier Coulomb Excitation of $^{106,108,110}$Sn
2020
International audience; A Coulomb excitation campaign on $^{106,108,110}$Sn at 4.4–4.5 MeV/u was launched at the HIE-ISOLDE facility at CERN. Larger excitation cross sections and γ-ray statistics were achieved compared to previous experiments at ∼2.8 MeV/u. More precise $(B(E2;0_{1}^{ + } \to 2_{1}^{ + }))$ values, lifetimes of states via the Doppler shift attenuation method, and new $(B(E2;0_{1}^{ + } \to 2_{x}^{ + })), (B(E2;2_{1}^{ + } \to 4_{1}^{ + }))$ and $(Q(2_{1}^{ + }))$ values from the new Miniball data will be obtained and applied to test modern nuclear structure theories.
Three-body correlations in electromagnetic dissociation of Borromean nuclei: The 6He case
2005
20 pages, 2 tables, 9 figures, 1 appendix.-- PACS nrs.: 25.60.-t; 27.20.+n; 25.70.De; 25.75.Gz.-- Printed version published Sep 5, 2005.
STUDIES OF 12C USING β-DECAYS
2008
The nuclear structure of states in 12 C have been a subject of interest for both theory and experiment since the early days of nuclear physics. Many open questions remain, especially concerning the existence and properties of 0+ and 2+ states in the triple alpha continuum. A series of experiments have been performed using β-decay of 12 N and 12 B to probe these states. The latest experiment was performed at KVI using an implantation method, measuring the sum energy of the three α-particles directly. Preliminary results from this experiment will be presented.
On the nuclear structure of 229Ra
1992
14 pages, 3 tables, 6 figures.
Systematic investigation of the drip-line nuclei 11Li and 14Be and their unbound subsystems 10Li and 13Be
2007
Fragmentation reactions in a carbon target with beams of 11Li and 14Be at relativistic energies have been studied in a kinematically complete experiment at the ALADIN-LAND setup at GSI. Excited states in 11Li and 14Be were obtained from the data in the inelastic channel. The measured cross sections with the core nucleus in the final state show that in the 14Be case core polarization plays an important role. In the one-neutron knockout channels the measured angular correlations between fragment and neutron are asymmetric, which demonstrates the presence of states with different parities in the 11Li and 14Be ground states. For 10Li a low-lying virtual s-state, a p-state and evidence for a d-s…
Nuclear shape transition in neutron-deficient gold isotopes
1987
4 pages, 1 table, 4 figures.
New information on 12C states from the decays of 12N and 12B
2003
Abstract The properties of states in 12 C above the 3α-threshold are of high current interest for nuclear astrophysics and for the nuclear many-body problem in general. We have initiated a series of experiments aimed at elucidating this region by using the β-decays of 12 N and 12 B. By applying the ISOL method for producing these radioactive isotopes, in combination with modern segmented charged particle detectors, our approach has significant advantages over previous studies of this region.
The new neutron-rich isotope228Rn
1989
2 pages, 1 table, 2 figures.-- PACS nrs.: 23.90.+w; 27.90.+b.-- Section: Short Notes.
Investigation of the Δn = 0 selection rule in Gamow-Teller transitions: The β-decay of 207Hg
2019
5 pags., 3 figs., 1 tab. -- Open Access funded by Creative Commons Atribution Licence 4.0
Two- and three-body correlations: breakup of halo nuclei
2004
4 pages, 2 figures.
Decay studies of the long-lived states in Tl-186
2020
9 pags., 12 figs., 3 tabs.
Two-proton emission in the decay of Ar-31
1998
18 pages, 7 figures, 2 tables.-- PACS nrs.: 23.40.Hc; 27.30.+t.
Octupole states in Tl207 studied through β decay
2020
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 st…
Light exotic isotopes: recent beam developments and physics applications at ISOLDE
2002
This paper is divided in three parts: (i) the measurement of yields and decay losses of Li and Be isotopes released from a thin foil tantalum target at the CERN/ISOLDE PS-Booster; (ii) results from beta-decay experiments on Be-12 and Be-14, an improved half-life of 21.49(3) ms has been obtained for Be-12; (iii) the beta-decay of C-9. An outline of the analysis procedure to determine the branching at high excitation energies is given. The ground-state branch has been determined to 54.1(15)%.
News on 12C from beta-decay studies
2004
We discuss the importance of the spectroscopic properties of the resonances of 12C just above the 3α-threshold, and review the existing experimental information of this region with emphasis on O+ and 2+ states. A new experimental approach for studying the β-decays of 12B and 12N is presented based on techniques developed in the context of Radioactive beam (rare isotope) physics. Finally preliminary results from an ongoing analysis of two recent experiments are given. © 2004 Published by Elsevier B.V.
The nuclear structure of $^{223}$Fr
1991
Abstract The γ-rays following the β− decay of 223Rn have been investigated by means of γ-ray singles including multispectrum analysis, and γγ-coincidence measurements using Ge detectors. Multipolarities of 38 transitions in 223Fr have been established by measuring conversion electrons with a mini-orange electron spectrometer. Most of the observed transitions could be placed in a level scheme comprising 53 excited states of 223Fr. The level structure is interpreted in terms of K π = 3 2 ± and 1 2 ± parity doublet bands, and a second K π = 3 2 ± higher-lying parity doublet. The experimental data are compared with the theoretical predictions of the reflection-asymmetric rotor model.
Searching for the 5H resonance in the t+n+n system
2003
19 pages, 7 figures, 2 tables, 2 appendices.-- PACS nrs.: 27.10.+h; 25.60.Gc.-- Printed version published Jul 28, 2003.
The β2p decay mechanism of Ar
2000
We have measured the beta-decay of Ar-31 with a high granularity setup sensitive to multiparticle decay branches. Two-proton emission is observed from the isobaric analog state in Cl-31 to the four lowest states in P-29 and furthermore from a large number of states fed in Gamow-Teller transitions. The mechanism of two-proton emission is studied via energy and angular correlations between the two protons. In all cases the mechanism is found to be sequential yielding information about states in S-30 up to 8 MeV excitation energy. Improved data on the beta-delayed one-proton branches together with the two-proton data provide precise information about the beta-strength distribution up to 15 MeV…
The β-decay approach for studying 12C
2008
6 pags., 3 figs. -- 9th International Conference on Clustering Aspects of Nuclear Structure and Dynamics (CLUSTERS'07) 3–7 September 2007, Stratford upon Avon, UK
Search for stable octupole deformation in $^{225}$Fr
1996
Levels in $^{225}$Fr have been studied by $\gamma$-ray and conversion-electron spectroscopy following the $\beta$-decay of $^{225}$Rn, and by the $^{226}$Ra(t,$\alpha$)$^{225}$Fr single-proton-pickup reaction. Multipolarities were obtained for $\sim$ 50 $\gamma$-transitions, and a level scheme was established in which definite spin-parity values were determined for over 20 of the 48 levels. Although low-lying rotational bands of both parities exist for $K=1/2$ and $K=3/2$, there is no experimental evidence to claim these are parity doublets. E1 strengths connecting the $K^\pi=3/2^\pm$ bands are intermediate between those for nuclides which are reflection symmetric and those claimed to be oc…
Influences on the triple alpha process beyond the Hoyle state
2010
7 pags., 3 figs. -- International Symposium on Nuclear Astrophysics - Nuclei in the Cosmos - IX, 25-30 June 2006, CERN
β decay studies of n-rich Cs isotopes with the ISOLDE Decay Station
2017
R. Lica et al. -- 14 pags., 7 figs., tab. -- Open Access funded by Creative Commons Atribution Licence 3.0
First Accurate Normalization of the β -delayed α Decay of N16 and Implications for the C12(α,γ)O16 Astrophysical Reaction Rate
2018
The C-12(alpha,gamma)O-16 reaction plays a central role in astrophysics, but its cross section at energies relevant for astrophysical applications is only poorly constrained by laboratory data. The reduced a width, gamma(11), of the bound 1(-) level in O-16 is particularly important to determine the cross section. The magnitude of gamma(11) is determined via sub-Coulomb a-transfer reactions or the beta-delayed a decay of N-16, but the latter approach is presently hampered by the lack of sufficiently precise data on the beta-decay branching ratios. Here we report improved branching ratios for the bound 1(-) level [b(beta,11) = (5.02 +/- 0.10) x 10(-2)] and for beta-delayed alpha emission [b(…
Clarification of the Three-Body Decay ofC12(12.71 MeV)
2003
Using $\ensuremath{\beta}$ decays of a clean source of $^{12}\mathrm{N}$ produced at the IGISOL facility, we have measured the breakup of the $^{12}\mathrm{C}$ (12.71 MeV) state into three $\ensuremath{\alpha}$ particles with a segmented particle detector setup. The high quality of the data permits solving the question of the breakup mechanism of the 12.71 MeV state, a longstanding problem in few-body nuclear physics. Among existing models, a modified sequential model fits the data best, but systematic deviations indicate that a three-body description is needed.
Precise branching ratios to unbound 12C states from 12N and 12B β-decays
2009
6 pages, 2 tables, 4 figures.--PACS nrs.: 21.45.-v; 23.40.-s; 27.20.+n; 21.60.De.--Printed version published Aug 3, 2009
Study of exotic decay of Cs isotope close to the proton drip line
2020
6 pags., 6 figs. -- 27th International Nuclear Physics Conference (INPC2019) 29 July - 2 August 2019, Glasgow, UK
Spectroscopy with β2p and β-ν recoil shifts
2002
9 pages, 4 figures.-- Printed version published Apr 22, 2002.
Enhanced Quadrupole and Octupole Strength in Doubly Magic Sn132
2018
The first 2+ and 3- states of the doubly magic nucleus Sn132 are populated via safe Coulomb excitation employing the recently commissioned HIE-ISOLDE accelerator at CERN in conjunction with the highly efficient MINIBALL array. The Sn132 ions are accelerated to an energy of 5.49 MeV/nucleon and impinged on a Pb206 target. Deexciting γ rays from the low-lying excited states of the target and the projectile are recorded in coincidence with scattered particles. The reduced transition strengths are determined for the transitions 0g.s.+→21+, 0g.s.+→31-, and 21+→31- in Sn132. The results on these states provide crucial information on cross-shell configurations which are determined within large-sca…
Competition between Allowed and First-Forbidden β Decay: The Case of Hg208→Tl208
2020
The β decay of ^{208}Hg into the one-proton hole, one neutron-particle _{81}^{208}Tl_{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_{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…
Sudden change in the nuclear charge distribution of very light gold isotopes
1987
4 pages, 3 tables, 2 figures.-- PACS nrs.: 21.10.Ft, 21.10.Ky, 27.70.+q.
Properties of the 12C 10 MeV state determined through β-decay
2005
16 pages, 1 table, 10 figures.-- PACS nrs.: 23.40.-s; 26.20.+f; 27.20.+n.-- Printed version published Oct 3, 2005.
Halo excitations in fragmentation of He at 240 MeV/u on carbon and lead targets
2000
Dissociation of a 240 MeV/u beam of He-6, incident on carbon and lead targets, has been studied in kinematically complete experiments to investigate low-lying excitation modes in the halo nucleus He-6. It is shown that alignment effects characterize the inelastic scattering and allow an unambiguous assignment of the spin of a narrow resonance observed in the excitation energy spectrum. The differential cross sections for the He-6 inelastic scattering on carbon and lead targets were deduced from the measured moments of the two neutrons and the a-particle. An analysis of these distributions shows that quadrupole and, possibly, monopole excitations characterize the hadronic interaction, while …
Projectile coulomb excitation with fast radioactive beams
1995
We report a search for gamma rays emanating from Coulomb excitation of fast (30-46 MeV/u) radioactive projectiles He-8, Be-11,Be-12,Be-14 interacting with a lead target. These are clearly identified by their Doppler shift. The 320 keV 1/2(-) --> 1/2(+)gamma transition from Be-11 was observed with a cross-section of 191 +/- 26 mb which is noticeably less than expected from the known lifetime and in the perturbation limit of pure Coulomb excitation. In the other nuclei rather stringent upper limits of 0.01 to 0.2 Weisskopf units, are placed on the hypothetical transition to 1(-) states.
Branching ratios in theβdecays ofN12andB12
2009
Absolute branching ratios to unbound states in C-12 populated in the beta decays of N-12 and B-12 are reported. Clean sources of N-12 and B-12 were obtained using the isotope separation on-line (ISOL) method. The relative branching ratios to the different populated states were extracted using single-alpha as well as complete kinematics triple-alpha spectra. These two largely independent methods give consistent results. Absolute normalization is achieved via the precisely known absolute branching ratio to the bound 4.44 MeV state in C-12. The extracted branching ratios to the unbound states are a factor of three more precise than previous measurements. Branching ratios in the decay of Na-20 …
Two-proton decay of the isobaric analogue state of Ar-31
1998
8 pages, 1 table, 4 figures.-- Journal issue title: "Nucleus-Nucleus Collisions".
Population of lead isotopes in binary reactions using a Rb 94 radioactive beam
2020
8 pags., 9 figs.
Breakup channels forC12triple-αcontinuum states
2009
The triple-alpha-particle breakup of states in the triple-alpha continuum of C-12 has been investigated by way of coincident detection of all three alpha particles of the breakup. The states have been fed in the beta decay of N-12 and B-12, and the alpha particles measured using a setup that covers all of the triple-alpha phase space. Contributions from the breakup through the Be-8(0(+)) ground state as well as other channels-interpreted as breakup through excited energies in Be-8-have been identified. Spins and parities of C-12 triple-alpha continuum states are deduced from the measured phase-space distributions for breakup through Be-8 above the ground state by comparison to a fully symme…
8He-6He: a comparative study of nuclear fragmentation reactions
2001
19 pages, 3 tables, 6 figures.-- PACS nrs.: 27.20.+n; 24.70.+s; 25.06.-t.-- Available online Dec 4, 2000.
He-8 - He-6: a comparative study of electromagnetic fragmentation reactions
2002
14 pages, 1 table, 2 figures.-- PACS nrs.:27.20.+n; 24.70.+.-- Available online Oct 8, 2001.
β decay of In133 : γ emission from neutron-unbound states in Sn133
2019
Excited states in Sn-133 were investigated through the beta decay of In-133 at the ISOLDE facility. The ISOLDE Resonance Ionization Laser Ion Source (RILIS) provided isomer-selective ionization for In-133, allowing us to study separately, and in detail, the beta-decay branch of In-133 J(pi)= (9/2(+)) ground state and its J(pi) = (1/2(-)) isomer.Thanks to the large spin difference of the two beta-decaying states of In-133, it is possible to investigate separately the lower and higher spin states in the daughter, Sn-133, and thus to probe independently different single-particle and single-hole levels. We report here new gamma transitions observed in the decay of In-133, including those assign…
The SPEDE spectrometer
2017
8 pags., 10 figs., 2 tabs.
Longitudinal and transverse momentum distributions of 9Li fragments from break-up of 11Li
1995
7 pages, 3 figures, 1 table.
Dissociation of 8He into 6He + n + X at 240 MeV/u
1995
4 pages, 3 figures, 2 tables.
First Accurate Normalization of the beta-delayed alpha Decay of N-16 and Implications for the C-12(alpha,gamma)O-16 Astrophysical Reaction Rate
2018
6 pags., 4 figs. -- Open Access funded by Creative Commons Atribution Licence 4.0
First -decay spectroscopy of and new -decay branches of
2021
19 pags., 14 figs., 3 tabs.