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Author |
Morales, A.I. et al |
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Title |
Type II shell evolution in A=70 isobars from the N >= 40 island of inversion |
Type |
Journal Article |
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Year |
2017 |
Publication |
Physics Letters B |
Abbreviated Journal |
Phys. Lett. B |
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Volume |
765 |
Issue  |
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Pages |
328-333 |
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Keywords |
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Abstract |
The level structures of Co-70 and Ni-70, populated from the Chi decay of Fe-70, have been investigated using beta-delayed gamma-ray spectroscopy following in-flight fission of a U-238 beam. The experimental results are compared to Monte-Carlo Shell-Model calculations including the pf + g(9/2) + d(5/2) orbitals. The strong population of a (1(+)) state at 274 keV in Co-70 is at variance with the expected excitation energy of 1 MeV from near spherical single-particle estimates. This observation indicates a dominance of prolate deformed intruder configurations in the low-lying levels, which coexist with the normal near spherical states. It is shown that the 13 decay of the neutron-rich A = 70 isobars from the new island of inversion to the Z = 28 closed-shell regime progresses in accordance with a newly reported type of shell evolution, the so-called Type II, which involves many particle-hole excitations across energy gaps. |
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Address |
[Morales, A. I.; Benzoni, G.; Nishimura, S.; Avigo, R.; Blasi, N.; Bracco, A.; Camera, F.; Ceruti, S.; Crespi, F. C. L.; Wieland, O.] Ist Nazl Fis Nucl, Sez Milano, Via Celoria 16, I-20133 Milan, Italy, Email: Ana.Morales@ific.uv.es |
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Publisher |
Elsevier Science Bv |
Place of Publication |
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Language |
English |
Summary Language |
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Abbreviated Series Title |
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Series Volume |
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ISSN |
0370-2693 |
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Conference |
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Notes |
WOS:000393627800044 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
3010 |
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Author |
BRIKEN Collaboration (Tarifeño-Saldivia, A. et al); Tain, J.L.; Domingo-Pardo, C.; Agramunt, J.; Algora, A.; Morales, A.I.; Rubio, B.; Tolosa, A. |
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Title |
Conceptual design of a hybrid neutron-gamma detector for study of beta-delayed neutrons at the RIB facility of RIKEN |
Type |
Journal Article |
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Year |
2017 |
Publication |
Journal of Instrumentation |
Abbreviated Journal |
J. Instrum. |
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Volume |
12 |
Issue |
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Pages |
P04006 - 22pp |
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Keywords |
Detector modelling and simulations I (interaction of radiation with matter, interaction; of photons with matter, interaction of hadrons with matter, etc); Instrumentation for radioactive beams (fragmentation devices; fragment and isotope, separators incl. ISOL; isobar separators; ion and atom traps; weak-beam diagnostics; radioactive-beam ion sources); Neutron detectors (cold, thermal, fast neutrons) |
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Abstract |
BRIKEN is a complex detection system to be installed at the RIB-facility of the RIKEN Nishina Center. It is aimed at the detection of heavy-ion implants, β-particles, γ-rays and β-delayed neutrons. The whole detection setup involves the Advanced Implantation Detection Array (AIDA), two HPGe Clover detectors and a large set of 166 counters of 3He embedded in a high-density polyethylene matrix. This article reports on a novel methodology developed for the conceptual design and optimisation of the 3He-tubes array, aiming at the best possible performance in terms of neutron detection. The algorithm is based on a geometric representation of two selected parameters of merit, namely, average neutron detection efficiency and efficiency flatness, as a function of a reduced number of geometric variables. The response of the detection system itself, for each configuration, is obtained from a systematic MC-simulation implemented realistically in Geant4. This approach has been found to be particularly useful. On the one hand, due to the different types and large number of 3He-tubes involved and, on the other hand, due to the additional constraints introduced by the ancillary detectors for charged particles and gamma-rays. Empowered by the robustness of the algorithm, we have been able to design a versatile detection system, which can be easily re-arranged into a compact mode in order to maximize the neutron detection performance, at the cost of the gamma-ray sensitivity. In summary, we have designed a system which shows, for neutron energies up to 1(5) MeV, a rather flat and high average efficiency of 68.6%(64%) and 75.7%(71%) for the hybrid and compact modes, respectively. The performance of the BRIKEN system has been also quantified realistically by means of MC-simulations made with different neutron energy distributions. |
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Address |
[Tarifeno-Saldivia, A.] UPC, Barcelona, Spain, Email: ariel.esteban.tarifeno@upc.edu |
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Publisher |
Iop Publishing Ltd |
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English |
Summary Language |
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Original Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
1748-0221 |
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Expedition |
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Conference |
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Notes |
WOS:000405067800006 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
3209 |
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Author |
Morales, A.I. et al |
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Title |
Is seniority a partial dynamic symmetry in the first νg(9/2) shell? |
Type |
Journal Article |
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Year |
2018 |
Publication |
Physics Letters B |
Abbreviated Journal |
Phys. Lett. B |
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Volume |
781 |
Issue |
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Pages |
706-712 |
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Keywords |
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Abstract |
The low-lying structures of the midshell vg(9/2) Ni isotopes Ni-72 and Ni-74 have been investigated at the RIBF facility in RIKEN within the EURICA collaboration. Previously unobserved low-lying states were accessed for the first time following beta decay of the mother nuclei Co-72 and Co-74. As a result, we provide a complete picture in terms of the seniority scheme up to the first (8(+)) levels for both nuclei. The experimental results are compared to shell-model calculations in order to define to what extent the seniority quantum number is preserved in the first neutron g(9/2) shell. We find that the disappearance of the seniority isomerism in the (8(1)(+)) states can be explained by a lowering of the seniority-four (6(+)) levels as predicted years ago. For Ni-74, the internal de-excitation pattern of the newly observed (6(2)(+)) state supports a restoration of the normal seniority ordering up to spin J = 4. This property, unexplained by the shell-model calculations, is in agreement with a dominance of the single-particle spherical regime near Ni-78. |
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Address |
[Morales, A. I.; Avigo, R.; Bracco, A.; Camera, F.; Ceruti, S.; Crespi, F. C. L.] Univ Milan, Dipartimento Fis, Via Celoria 16, I-20133 Milan, Italy, Email: Ana.Morales@ific.uv.es |
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Corporate Author |
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Thesis |
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Publisher |
Elsevier Science Bv |
Place of Publication |
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Editor |
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Language |
English |
Summary Language |
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Original Title |
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Series Editor |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0370-2693 |
ISBN |
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Area |
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Expedition |
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Conference |
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Notes |
WOS:000435653100092 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
3635 |
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Author |
BRIKEN Collaboration (Tolosa-Delgado, A. et al); Agramunt, J.; Tain, J.L.; Algora, A.; Domingo-Pardo, C.; Morales, A.I.; Rubio, B. |
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Title |
Commissioning of the BRIKEN detector for the measurement of very exotic beta-delayed neutron emitters |
Type |
Journal Article |
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Year |
2019 |
Publication |
Nuclear Instruments & Methods in Physics Research A |
Abbreviated Journal |
Nucl. Instrum. Methods Phys. Res. A |
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Volume |
925 |
Issue |
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Pages |
133-147 |
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Keywords |
Beta-delayed neutrons; Neutron and beta counters; Analysis methodology; Background correction |
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Abstract |
A new detection system has been installed at the RIKEN Nishina Center (Japan) to investigate decay properties of very neutron-rich nuclei. The setup consists of three main parts: a moderated neutron counter, a detection system sensitive to the implantation and decay of radioactive ions, and gamma-ray detectors. We describe here the setup, the commissioning experiment and some selected results demonstrating its performance for the measurement of half-lives and beta-delayed neutron emission probabilities. The methodology followed in the analysis of the data is described in detail. Particular emphasis is placed on the correction of the accidental neutron background. |
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Address |
[Tolosa-Delgado, A.; Agramunt, J.; Tain, J. L.; Algora, A.; Domingo-Pardo, C.; Morales, A., I; Rubio, B.] CSIC, Inst Fis Corpuscular, E-46980 Paterna, Spain, Email: tain@ific.uv.es |
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Corporate Author |
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Thesis |
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Publisher |
Elsevier Science Bv |
Place of Publication |
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Editor |
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Language |
English |
Summary Language |
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Original Title |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0168-9002 |
ISBN |
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Medium |
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Area |
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Conference |
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Notes |
WOS:000460539400018 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
3939 |
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Author |
Saha, S.; Arici, T.; Gerl, J.; Gorska, M.; Pietralla, N.; Davinson, T.; Morales, A.I.; Podolyak, Z. |
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Title |
On the 6-detection efficiency of a combined Si and plastic stack detector for DESPEC |
Type |
Journal Article |
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Year |
2020 |
Publication |
Nuclear Instruments & Methods in Physics Research A |
Abbreviated Journal |
Nucl. Instrum. Methods Phys. Res. A |
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Volume |
975 |
Issue |
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Pages |
164196 - 8pp |
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Keywords |
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Abstract |
A Geant4 simulation has been carried out in order to determine the beta-detection efficiency of a rare isotope beam implantation setup, for decay spectroscopy experiments, comprising a number of Double Sided Silicon Strip Detectors (DSSSDs) and two plastic scintillation detectors placed upstream and downstream. The absolute efficiency for the emitted beta-particle detection from radioactive fragments implanted in the DSSSDs using fast-timing plastic-scintillator detector, is calculated. The detection efficiency of the setup has been studied with two different distances between the Si layers and plastics. The requirement for the thickness of the Si detector layers and its implication on the beta-detection efficiency has been investigated for 1 mm and 300 µm thickness of Si layers. The combined efficiency of DSSSD and plastic detectors were also simulated for two different thicknesses of the DSSSD. |
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Address |
[Saha, S.; Arici, T.; Gerl, J.; Gorska, M.] GSI Helmholtzzentrum Schwerionenforsch, Planckstr 1, D-64291 Darmstadt, Germany, Email: Sudipta_Saha@uml.edu |
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Corporate Author |
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Thesis |
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Publisher |
Elsevier |
Place of Publication |
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Editor |
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Language |
English |
Summary Language |
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Original Title |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0168-9002 |
ISBN |
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Area |
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Expedition |
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Conference |
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Notes |
WOS:000539967000003 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
4427 |
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