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42 results on '"Ovejas, J. D."'

1. Decay study of $^{11}$Be with an Optical TPC detector

Author

Sokołowska, N., Guadilla, V., Mazzocchi, C., Ahmed, R., Borge, M., Cardella, G., Ciemny, A. A., Cosentino, L. G., De Filippo, E., Fedosseev, V., Fijałkowska, A., Fraile, L. M., Geraci, E., Giska, A., Gnoffo, B., Granados, C., Janas, Z., Janiak, Ł., Johnston, K., Kamiński, G., Korgul, A., Kubiela, A., Maiolino, C., Marsh, B., Martorana, N. S., Miernik, K., Molkanov, P., Ovejas, J. D., Pagano, E. V., Pirrone, S., Pomorski, M., Quynh, A. M., Riisager, K., Russo, A., Russotto, P., Świercz, A., Viñals, S., Wilkins, S., and Pfützner, M.

Subjects
Nuclear Experiment
Abstract

The $\beta$ decay of one-neutron halo nucleus $^{11}$Be was investigated using the Warsaw Optical Time Projection Chamber (OTPC) detector to measure $\beta$-delayed charged particles. The results of two experiments are reported. In the first one, carried out in LNS Catania, the absolute branching ratio for $\beta$-delayed $\alpha$ emission was measured by counting incoming $^{11}$Be ions stopped in the detector and the observed decays with the emission of $\alpha$ particle. The result of 3.27(46)\% is in good agreement with the literature value. In the second experiment, performed at the HIE-ISOLDE facility at CERN, bunches containing several hundreds of $^{11}$Be ions were implanted into the OTPC detector followed by the detection of decays with the emission of charged particles. The energy spectrum of $\beta$-delayed $\alpha$ particles was determined in the full energy range. It was analysed in the R-matrix framework and was found to be consistent with the literature. The best description of the spectrum was obtained assuming that the two $3/2^+$ and one $1/2^+$ states in $^{11}$B are involved in the transition. The search for $\beta$-delayed emission of protons was undertaken. Only the upper limit for the branching ratio for this process of $(2.2 \pm 0.6_{\rm stat} \pm 0.6_{\rm sys}) \times 10^{-6}$ could be determined. This value is in conflict with the result published in [Ayyad et al. Phys. Rev. Lett. 123, 082501 (2019)] but does agree with the limit reported in [Riisager et al., Eur. Phys. J. A (2020) 56:100], Comment: 16 pages, 18 figures, submitted to Phys. Rev. C

Published
2024

2. Study of the $^7$Be($d$,$^3$He)$^6$Li* reaction at 5 MeV/u

Author

Ali, Sk M., Gupta, D., Kundalia, K., Maity, S., Saha, Swapan K, Tengblad, O., Ovejas, J. D., Perea, A., Martel, I., Cederkall, J., Park, J., and Moro, A. M.

Subjects
Nuclear Experiment
Abstract

The measurement of the $^7$Be($d$,$^3$He)$^6$Li* transfer cross section at 5 MeV/u is carried out. The population of the 2.186 MeV excited state of $^6$Li in this reaction channel is observed for the first time. The experimental angular distributions have been analyzed in the finite range DWBA and coupled-channel frameworks. The effect of the $^7$Be($d$,$^3$He)$^6$Li reaction on both the $^6$Li and $^7$Li abundances are investigated at the relevant big-bang nucleosynthesis energies. The excitation function is calculated by TALYS and normalized to the experimental data. The $S$ factor of the ($d$,$^3$He) channel from the present work is about 50$\%$ lower than existing data at nearby energies. At big-bang energies, the $S$ factor is about three orders of magnitude smaller than that of the ($d,p$) channel. The ($d$,$^3$He) reaction rate is found to have a less than 0.1$\%$ effect on the $^{6,7}$Li abundances., Comment: 7 pages, 5 figures

Published
2024
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3. Simultaneous $\gamma$-ray and electron spectroscopy of $^{182,184,186}$Hg isotopes

Author

Stryjczyk, M., Andel, B., Cubiss, J. G., Rezynkina, K., Rodríguez, T. R., García-Ramos, J. E., Andreyev, A. N., Pakarinen, J., Van Duppen, P., Antalic, S., Berry, T., Borge, M. J. G., Clisu, C., Cox, D. M., De Witte, H., Fraile, L. M., Fynbo, H. O. U., Gaffney, L. P., Harkness-Brennan, L. J., Huyse, M., Illana, A., Judson, D. S., Konki, J., Kurcewicz, J., Lazarus, I., Lica, R., Madurga, M., Marginean, N., Marginean, R., Mihai, C., Mosat, P., Nacher, E., Negret, A., Ojala, J., Ovejas, J. D., Page, R. D., Papadakis, P., Pascu, S., Perea, A., Podolyák, Zs., Próchniak, L., Pucknell, V., Rapisarda, E., Rotaru, F., Sotty, C., Tengblad, O., Vedia, V., Viñals, S., Wadsworth, R., Warr, N., and Wrzosek-Lipska, K.

Subjects
Nuclear Experiment, Nuclear Theory
Abstract

Background: The mercury isotopes around $N=104$ are a well-known example of nuclei exhibiting shape coexistence. Mixing of configurations can be studied by measuring the monopole strength $\rho^2(E0)$, however, currently the experimental information is scarce and lacks precision, especially for the $I^\pi \rightarrow I^\pi$ ($I \neq 0$) transitions. Purpose: The goals of this study were to increase the precision of the known branching ratios and internal conversion coefficients, to increase the amount of available information regarding excited states in $^{182,184,186}$Hg and to interpret the results in the framework of shape coexistence using different models. Method: The low-energy structures in $^{182,184,186}$Hg were populated in the $\beta$ decay of $^{182,184,186}$Tl, produced at ISOLDE and purified by laser ionization and mass separation. The $\gamma$-ray and internal conversion electron events were detected by five germanium clover detectors and a segmented silicon detector, respectively, and correlated in time to build decay schemes. Results: In total, 193, 178 and 156 transitions, including 144, 140 and 108 observed for the first time in a $\beta$-decay experiment, were assigned to $^{182,184,186}$Hg, respectively. Internal conversion coefficients were determined for 23 transitions, out of which 12 had an $E0$ component. Extracted branching ratios allowed the sign of the interference term in $^{182}$Hg as well as $\rho^2(E0;0^+_2\rightarrow 0^+_1)$ and $B(E2;0^+_2\rightarrow 2^+_1)$ in $^{184}$Hg to be determined. By means of electron-electron coincidences, the $0^+_3$ state was identified in $^{184}$Hg. The experimental results were qualitatively reproduced by five theoretical approaches, the IBM with configuration mixing with two different parametrizations, the General Bohr Hamiltonian, the BMF model and the SCCM model. However, a quantitative description is lacking., Comment: 21 pages, 30 figures, accepted for publication in Physical Review C

Published
2023
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4. Study of elastic and inelastic scattering of $^7$Be + $^{12}$C at 35 MeV

Author

Kundalia, K., Gupta, D., Ali, Sk M., Saha, Swapan K, Tengblad, O., Ovejas, J. D., Perea, A., Martel, I., Cederkall, J., Park, J., Szwec, S., and Moro, A. M.

Subjects
Nuclear Experiment, Nuclear Theory
Abstract

The elastic and inelastic scattering of $^7$Be from $^{12}$C have been measured at an incident energy of 35 MeV. The inelastic scattering leading to the 4.439 MeV excited state of $^{12}$C has been measured for the first time. The experimental data cover an angular range of $\theta_{cm}$ = 15$^{\circ}$-120$^{\circ}$. Optical model analyses were carried out with Woods-Saxon and double-folding potential using the density dependent M3Y (DDM3Y) effective interaction. The microscopic analysis of the elastic data indicates breakup channel coupling effect. A coupled-channel analysis of the inelastic scattering, based on collective form factors, show that mutual excitation of both $^7$Be and $^{12}$C is significantly smaller than the single excitation of $^{12}$C. The larger deformation length obtained from the DWBA analysis could be explained by including the excitation of $^7$Be in a coupled-channel analysis. The breakup cross section of $^7$Be is estimated to be less than 10$\%$ of the reaction cross section. The intrinsic deformation length obtained for the $^{12}$C$^*$ (4.439 MeV) state is $\delta _2$ = 1.37 fm. The total reaction cross section deduced from the analysis agrees very well with Wong's calculations for similar weakly bound light nuclei on $^{12}$C target., Comment: 8 pages, 5 figures

Published
2022
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5. Resonance excitations in $^7$Be(d,p)$^8$Be$^\ast$ to address the cosmological lithium problem

Author

Ali, Sk M., Gupta, D., Kundalia, K., Saha, Swapan K., Tengblad, O., Ovejas, J. D., Perea, A., Martel, I., Cederkall, J., Park, J., and Szwec, S.

Subjects
Nuclear Experiment
Abstract

The anomaly in lithium abundance is a well-known unresolved problem in nuclear astrophysics. A recent revisit to the problem tried the avenue of resonance enhancement to account for the primordial $^7$Li abundance in standard big-bang nucleosynthesis (BBN). Prior measurements of the $^7$Be(d,p)$^8$Be* reaction could not account for the individual contributions of the different excited states involved, particularly at higher energies close to the Q-value of the reaction. We carried out an experiment at HIE-ISOLDE, CERN to study this reaction at E$_{cm}$ = 7.8 MeV, populating excitations up to 22 MeV in $^8$Be for the first time. The angular distributions of the several excited states have been measured and the contributions of the higher excited states in the total cross section at the relevant big-bang energies were obtained by extrapolation to the Gamow window using the TALYS code. The results show that by including the contribution of the 16.63 MeV state, the maximum value of the total S-factor inside the Gamow window comes out to be 167 MeV b as compared to earlier estimate of 100 MeV b. However, this still does not account for the lithium discrepancy., Comment: 5 pages, 5 figures

Published
2022
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6. Decay studies of the long-lived states in $^{186}$Tl

Author

Stryjczyk, M., Andel, B., Andreyev, A. N., Cubiss, J., Pakarinen, J., Rezynkina, K., Van Duppen, P., Antalic, S., Berry, T., Borge, M. J. G., Clisu, C., Cox, D. M., De Witte, H., Fraile, L. M., Fynbo, H. O. U., Gaffney, L. P., Harkness-Brennan, L. J., Huyse, M., Illana, A., Judson, D. S., Konki, J., Kurcewicz, J., Lazarus, I., Lica, R., Madurga, M., Marginean, N., Marginean, R., Mihai, C., Mosat, P., Nacher, E., Negret, A., Ojala, J., Ovejas, J. D., Page, R. D., Papadakis, P., Pascu, S., Perea, A., Podolyák, Zs., Pucknell, V., Rapisarda, E., Rotaru, F., Sotty, Ch., Tengblad, O., Vedia, V., Viñals, S., Wadsworth, R., Warr, N., and Wrzosek-Lipska, K.

Subjects
Nuclear Experiment
Abstract

Decay spectroscopy of the long-lived states in $^{186}$Tl has been performed at the ISOLDE Decay Station at ISOLDE, CERN. The $\alpha$ decay from the low-spin $(2^-)$ state in $^{186}$Tl was observed for the first time and a half-life of $3.4^{+0.5}_{-0.4}$ s was determined. Based on the $\alpha$-decay energy, the relative positions of the long-lived states were fixed, with the $(2^-)$ state as the ground state, the $7^{(+)}$ state at 77(56)~keV and the $10^{(-)}$ state at 451(56) keV. The level scheme of the internal decay of the $^{186}$Tl($10^{(-)}$) state ($T_{1/2} = 3.40(9)$ s), which was known to decay solely through emission of 374 keV $\gamma$-ray transition, was extended and a lower-limit for the $\beta$-decay branching $b_\beta > 5.9(3)\%$ was determined. The extracted retardation factors for the $\gamma$ decay of the $10^{(-)}$ state were compared to the available data in neighboring odd-odd thallium isotopes indicating the importance of the $\pi d_{3/2}$ shell in the isomeric decay and significant structure differences between $^{184}$Tl and $^{186}$Tl., Comment: 10 pages, 12 figures

Published
2020
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7. Measurement of the $2^+\rightarrow 0^+$ ground-state transition in the $\beta$ decay of $^{20}$F

Author

Kirsebom, O. S., Hukkanen, M., Kankainen, A., Trzaska, W. H., Strömberg, D. F., Martínez-Pinedo, G., Andersen, K., Bodewits, E., Canete, L., Cederkäll, J., Enqvist, T., Eronen, T., Fynbo, H. O. U., Geldhof, S., de Groote, R., Jenkins, D. G., Jokinen, A., Joshi, P., Khanam, A., Kostensalo, J., Kuusiniemi, P., Moore, I., Munch, M., Nesterenko, D. A., Ovejas, J. D., Penttilä, H., Pohjalainen, I., Reponen, M., Rinta-Antila, S., Riisager, K., de Roubin, A., Schotanus, P., Srivastava, P. C., Suhonen, J., Swartz, J. A., Tengblad, O., Vilen, M., Vińals, S., and Äystö, J.

Subjects
Nuclear Experiment
Abstract

We report the first detection of the second-forbidden, non-unique, $2^+\rightarrow 0^+$, ground-state transition in the $\beta$ decay of $^{20}$F. A low-energy, mass-separated $^{20}\rm{F}^+$ beam produced at the IGISOL facility in Jyv\"askyl\"a, Finland, was implanted in a thin carbon foil and the $\beta$ spectrum measured using a magnetic transporter and a plastic-scintillator detector. The $\beta$-decay branching ratio inferred from the measurement is $b_{\beta} = [ 0.41\pm 0.08\textrm{(stat)}\pm 0.07\textrm{(sys)}] \times 10^{-5}$ corresponding to $\log ft = 10.89(11)$, making this one of the strongest second-forbidden, non-unique $\beta$ transitions ever measured. The experimental result is supported by shell-model calculations and has significant implications for the final evolution of stars that develop degenerate oxygen-neon cores. Using the new experimental data, we argue that the astrophysical electron-capture rate on $^{20}$Ne is now known to within better than 25% at the relevant temperatures and densities., Comment: 13 pages, 16 figures, 4 tables

Published
2018
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10. Suppression of Coulomb-nuclear interference in the near-barrier elastic scattering of 17Ne from 208Pb

Author

European Commission, National Science Centre (Poland), Ministerio de Ciencia e Innovación (España), #NODATA#, Martel, I. [0000-0002-4895-2305], Ovejas, J. D., Martel, I., Dell'Aquila, D., Acosta, L., Aguado, J. L., de Angelis, G., García Borge, María José, Briz, José Antonio, Chbihi, A., Colucci, G., Díaz-Martín, C., Figuera, P., Galaviz, D., García-Ramos, C., Gómez-Galán, J. A., Gonzales, C. A., Goyal, N., Keeley, N., Kemper, K. W., Kurtukian-Nieto, T., Malenica, D. J., Mazzocco, M., Nurkić, D., Orduz, A. K., Ortiz, A., Palada, L., Parascandolo, C., Di Pietro, A., Rodriguez, A. M., Rusek, K., Salguero, F., Sánchez-Benítez, A. M., Sánchez-Raya, M., Sánchez-Segovia, J., Soić, N., Soramel, F., Stanoiu, M., Tengblad, Olof, Vukman, N., Xarepe, M., European Commission, National Science Centre (Poland), Ministerio de Ciencia e Innovación (España), #NODATA#, Martel, I. [0000-0002-4895-2305], Ovejas, J. D., Martel, I., Dell'Aquila, D., Acosta, L., Aguado, J. L., de Angelis, G., García Borge, María José, Briz, José Antonio, Chbihi, A., Colucci, G., Díaz-Martín, C., Figuera, P., Galaviz, D., García-Ramos, C., Gómez-Galán, J. A., Gonzales, C. A., Goyal, N., Keeley, N., Kemper, K. W., Kurtukian-Nieto, T., Malenica, D. J., Mazzocco, M., Nurkić, D., Orduz, A. K., Ortiz, A., Palada, L., Parascandolo, C., Di Pietro, A., Rodriguez, A. M., Rusek, K., Salguero, F., Sánchez-Benítez, A. M., Sánchez-Raya, M., Sánchez-Segovia, J., Soić, N., Soramel, F., Stanoiu, M., Tengblad, Olof, Vukman, N., and Xarepe, M.

Abstract

The proton drip-line nucleus 17Ne is considered a good candidate for a Borromean two-proton halo with a 15O + p + p structure. Angular distributions of the elastic scattering and inclusive 15O production for a 136 MeV 17Ne beam incident on a 208Pb target were measured for the first time at the SPIRAL1 facility, GANIL. Use of the GLORIA detector array allowed high-resolution data over a wide angular range from 20∘ up to 95∘ in the laboratory frame to be obtained. The elastic scattering angular distribution shows similarities with those for both 6He and 20Ne at equivalent collision energies with respect to the corresponding Coulomb barriers, exhibiting the suppression of the Coulomb rainbow peak characteristic of strong coupling. Optical model and coupled channel fits suggest that this is due to a combination of coupling to low-lying quadrupole resonances and Coulomb dipole coupling to the low-lying continuum, although their relative importance depends on the relevant B(E2) values which remain to be firmly determined.

Published
2023

11. A prototype of pCT scanner: first tests

Author

Briz J. A., Posadillo I., Távora V.G., Nácher E., Borge M.J.G., Tengblad O., Perea A., Ortiz A., Ovejas J. D., and Viñals S.

Subjects
proton, proton therapy, proton computed tomography, particle tracking, silicon detectors, dssd, scintillators, labr3, Physics, QC1-999
Abstract

Proton therapy technique for cancer treatment offers a high selectivity with respect to conventional radiotherapy with X- and γ-rays due to the properties of the interaction of protons with matter. Very accurate and precise treatment plans and a good control on the dose deposition are required to exploit the full potential of the technique. The substitution of the currently used X-ray Computed Tomography (xCT) by proton Computed Tomography (pCT) in the design of treatment plans would allow for a reduction in proton range uncertainties. This would make possible an important improvement in the accuracy and precision of treatment plans. With this aim, a prototype of pCT scanner is under study. It includes two tracking detectors which provide information on the proton trajectories and a residual energy detector to determine the energy loss while traversing the object scanned. A proof-of-concept experiment has been performed using low-energy protons and a simplified prototype with only the two tracking detectors. The results obtained in the measurement are presented and discussed.

Published
2021
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13. Resonance Excitations in Be 7 (d,p) Be∗ 8 to Address the Cosmological Lithium Problem

Author

European Commission, Indian Space Research Organisation, Agencia Estatal de Investigación (España), Ministerio de Ciencia, Innovación y Universidades (España), Swedish Research Council, Royal Physiographic Society of Lund, Institute for Basic Science (South Korea), Academy of Finland, Ali, S.M., Gupta, D., Kundalia, K., Saha, S.K., Tengblad, Olof, Ovejas, J. D., Perea, Ángel, Martel, Ismael, Cederkall, J., Park, J., Szwec, S., European Commission, Indian Space Research Organisation, Agencia Estatal de Investigación (España), Ministerio de Ciencia, Innovación y Universidades (España), Swedish Research Council, Royal Physiographic Society of Lund, Institute for Basic Science (South Korea), Academy of Finland, Ali, S.M., Gupta, D., Kundalia, K., Saha, S.K., Tengblad, Olof, Ovejas, J. D., Perea, Ángel, Martel, Ismael, Cederkall, J., Park, J., and Szwec, S.

Abstract

The anomaly in lithium abundance is a well-known unresolved problem in nuclear astrophysics. A recent revisit to the problem tried the avenue of resonance enhancement to account for the primordial Li7 abundance in standard big-bang nucleosynthesis. Prior measurements of the Be7(d,p)Be∗8 reaction could not account for the individual contributions of the different excited states involved, particularly at higher energies close to the Q value of the reaction. We carried out an experiment at HIE-ISOLDE, CERN to study this reaction at Ec.m.=7.8 MeV, populating excitations up to 22 MeV in Be8 for the first time. The angular distributions of the several excited states have been measured and the contributions of the higher excited states in the total cross section at the relevant big-bang energies were obtained by extrapolation to the Gamow window using the talys code. The results show that by including the contribution of the 16.63 MeV state, the maximum value of the total S factor inside the Gamow window comes out to be 167 MeV b as compared to earlier estimate of 100 MeV b. However, this still does not account for the lithium discrepancy.

Published
2022

14. Resonance Excitations in 7Be(d,p)8Be* to Address the Cosmological Lithium Problem

Author

Ali, Sk M., Gupta, D., Kundalia, K., Saha Swapan, K., Tengblad, O., Ovejas, J. D., Perea, A., Martel, I., Cederkall, J., Park, J., and Szwec, S.

Subjects
isotoopit, litium, astrofysiikka, alkuräjähdys, beryllium, ydinfysiikka
Abstract

The anomaly in lithium abundance is a well-known unresolved problem in nuclear astrophysics. A recent revisit to the problem tried the avenue of resonance enhancement to account for the primordial 7Li abundance in standard big-bang nucleosynthesis. Prior measurements of the 7Be(d,p)8Be∗ reaction could not account for the individual contributions of the different excited states involved, particularly at higher energies close to the Q value of the reaction. We carried out an experiment at HIE-ISOLDE, CERN to study this reaction at Ec.m.=7.8 MeV, populating excitations up to 22 MeV in 8Be for the first time. The angular distributions of the several excited states have been measured and the contributions of the higher excited states in the total cross section at the relevant big-bang energies were obtained by extrapolation to the Gamow window using the talys code. The results show that by including the contribution of the 16.63 MeV state, the maximum value of the total S factor inside the Gamow window comes out to be 167 MeV b as compared to earlier estimate of 100 MeV b. However, this still does not account for the lithium discrepancy. peerReviewed

Published
2022

15. Study of elastic and inelastic scattering of 7Be + 12C at 35 MeV

Author

Kundalia, Kabita, Gupta, Dhruba, Ali, Sk M., Saha, Swapan K., Tengblad, Olof, Ovejas, J. D., Perea, Ángel, Martel Bravo, Ismael, Moro Muñoz, Antonio Matías, Universidad de Sevilla. Departamento de Física Atómica, Molecular y Nuclear, European Union (UE). H2020, Indian Space Research Organisation (ISRO), Ministerio de Ciencia e Innovación (MICIN). España, Swedish Research Council, Institute for Basic Sciencie (Korea), Academy of Finland, and Junta de Andalucía

Abstract

The elastic and inelastic scattering of 7Be from 12C have been measured at an incident energy of 35 MeV. The inelastic scattering leading to the 4.439 MeV excited state of 12C has been measured for the first time. The experimental data cover an angular range of θcm = 15∘-120∘. Optical model analyses were carried out with Woods-Saxon and double-folding potential using the density dependent M3Y (DDM3Y) effective interaction. The microscopic analysis of the elastic data indicates breakup channel coupling effect. A coupled-channel analysis of the inelastic scattering, based on collective form factors, shows that mutual excitation of both 7Be and 12C is significantly smaller than the single excitation of 12C. The larger deformation length obtained from the DWBA analysis could be explained by including the excitation of 7Be in a coupled-channel analysis. The breakup cross section of 7Be is estimated to be less than 10% of the reaction cross section. The intrinsic deformation length obtained for the 12C⁎ (4.439 MeV) state is δ2 = 1.37 fm. The total reaction cross section deduced from the analysis agrees very well with Wong's calculations for similar weakly bound light nuclei on 12C target. European Union H2020 654002 (ENSAR2) Indian Space Research Organisation ISRO/RES/2/378/15-16. O Ministerio de Ciencia e Innovación PID2019-104390GB-I00, PGC2018-095640-B-I00, PID2020-114687GB-I00 Swedish Research Council VR-2017-00637, VR-2017- 03986 Institute for Basis Sciencie IBS-R031-D1 Academy of Finland 307685 Junta de Andalucía FQM-160, P20_01247

Published
2022

16. Probing proton halo effects in the 8B+64Zn collision around the Coulomb barrier

Author

European Commission, Istituto Nazionale di Fisica Nucleare, Ministerio de Ciencia, Innovación y Universidades (España), Sparta, Roberta, Pietro, A. di, Figuera, P., Tengblad, Olof, Moro, A.M., Martel, Ismael, Fernández-García, J. P., Lei, J., Acosta, Luis, Borge, María José G., Bruni, G., Cederkäll, Joakim, Davinson, Thomas, Ovejas, J. D., Fraile, Luis M., Galaviz, D., Halkjaer Jensen, Jesper, Jonson, Björn, Cognata, M. La, Perea, Ángel, Sánchez-Benítez, A. M., Soic, Neven, Viñals, S., European Commission, Istituto Nazionale di Fisica Nucleare, Ministerio de Ciencia, Innovación y Universidades (España), Sparta, Roberta, Pietro, A. di, Figuera, P., Tengblad, Olof, Moro, A.M., Martel, Ismael, Fernández-García, J. P., Lei, J., Acosta, Luis, Borge, María José G., Bruni, G., Cederkäll, Joakim, Davinson, Thomas, Ovejas, J. D., Fraile, Luis M., Galaviz, D., Halkjaer Jensen, Jesper, Jonson, Björn, Cognata, M. La, Perea, Ángel, Sánchez-Benítez, A. M., Soic, Neven, and Viñals, S.

Abstract

Proton halo effects in the B+Zn reaction at an energy around 1.5 times the Coulomb barrier have been studied at HIE-ISOLDE CERN using, for the first time, the only existing postaccelerated B beam. This, together with the use of a high granularity and large solid angle detection system, allowed for a careful mapping of the elastic angular distribution, especially in the Coulomb-nuclear interference region. Contrary to what is observed for the one-neutron halo nucleus Be on the same target in a similar energy range, the analysis of the elastic scattering angular distribution shows only a modest suppression of the Coulomb-nuclear interference peak, with no remarkable enhancement of the total reaction cross-section. Inclusive angular and energy distributions of Be produced in direct reaction processes have also been measured. The comparison of these data with the results of theoretical calculations for the elastic and non-elastic breakup contributions indicate that both processes are important. Overall, the experimental data suggest a B collision dynamics at the barrier very different from the one of neutron halo nuclei, showing only modest effects of coupling to continuum. This behaviour can be interpreted as due to the presence of the additional Coulomb interactions halo-core and halo-target together with the presence of the centrifugal barrier felt by the valence proton of B.

Published
2021

17. The experiments to determine the electron capture and β-decay of 8B into the highly excited states of 8Be

Author

Vinals, S., Borge, M. J.G., Tengblad, O., Nácher, E., Benito, J., Figuera, P., Fraile, L. M., Fynbo, H. O.U., Gad, A., Jensen, J., Jonson, B., Lica, R., Marroquín, I., Munch, M., Nilsson, T., Ovejas, J. D., Perea, A., Riisager, K., Smain, S., and Sotty, C.

Abstract

The main goal of this work is to study the structure of the highest energy states in 8Be populated following the β+-decay and the electron capture (EC) of 8B. With this aim, two experiments were performed at ISOLDE-CERN in 2017 and 2018. The first experiment had the aim to resolve the 2+ doublet at 16.6 and 16.9 MeV, in order to study their isospin mixing. The second experiment aimed to determine a value or give an experimental upper limit to the branching ratio of the exotic EC-p decay. In this paper, we present the experimental setups and we discuss the analysis and present the preliminary results obtained so far.

Published
2020

18. Decay studies of the long-lived states in 186 Tl

Author

Stryjczyk, M., Andel, B., Andreyev, A. N., Cubiss, J., Pakarinen, J., Rezynkina, K., Van Duppen, P., Antalic, S., Berry, T., Borge, M. J.G., Clisu, C., Cox, D. M., De Witte, H., Fraile, L. M., Gaffney, L. P., Harkness-Brennan, L. J., Huyse, M., Illana, A., Judson, D. S., Konki, J., Kurcewicz, J., Lazarus, I., Lica, R., Madurga, M., Marginean, N., Marginean, R., Mihai, C., Mosat, P., Nacher, E., Negret, A., Ojala, J., Ovejas, J. D., Page, R. D., Papadakis, P., Pascu, S., Perea, A., Podolyák, Zs, Pucknell, V., Rapisarda, E., Rotaru, F., Sotty, C., Tengblad, O., Vedia, V., Viñals, S., Wadsworth, R., Warr, N., and Wrzosek-Lipska, K.

Subjects
High Energy Physics::Experiment
Abstract

Decay spectroscopy of the long-lived states in Tl186 has been performed at the ISOLDE Decay Station at ISOLDE, CERN. The α decay from the low-spin (2-) state in Tl186 was observed for the first time and a half-life of 3.4-0.4+0.5 s was determined. Based on the α-decay energy, the relative positions of the long-lived states were fixed, with the (2-) state as the ground state, the 7(+) state at 77(56) keV, and the 10(-) state at 451(56) keV. The level scheme of the internal decay of the Tl186(10(-)) state [T1/2=3.40(9) s], which was known to decay solely through emission of 374-keV γ-ray transition, was extended and a lower limit for the β-decay branching bβ>5.9(3)% was determined. The extracted retardation factors for the γ decay of the 10(-) state were compared to the available data in neighboring odd-odd thallium isotopes indicating the importance of the πd3/2 shell in the isomeric decay and significant structure differences between Tl184 and Tl186.

Published
2020

19. Decay studies of the long-lived states in Tl186

Author

Stryjczyk, M., Andel, B., Andreyev, A. N., Cubiss, J., Pakarinen, J., Rezynkina, K., Van Duppen, P., Antalic, S., Berry, T., Borge, M. J. G., Clisu, C., Cox, D. M., De Witte, H., Fraile, L. M., Fynbo, H. O. U., Gaffney, L. P., Harkness-Brennan, L. J., Huyse, M., Illana, A., Judson, D. S., Konki, J., Kurcewicz, J., Lazarus, I., Lica, R., Madurga, M., Marginean, N., Marginean, R., Mihai, C., Mosat, P., Nacher, E., Negret, A., Ojala, J., Ovejas, J. D., Page, R. D., Papadakis, P., Pascu, S., Perea, A., Podolyák, Zs., Pucknell, V., Rapisarda, E., Rotaru, F., Sotty, C., Tengblad, O., Vedia, V., Viñals, S., Wadsworth, R., Warr, N., and Wrzosek-Lipska, K.

Subjects
lifetimes and widths, alpha decay, electromagnetic transitions, High Energy Physics::Experiment, isomer decays, ydinfysiikka, nuclear structure and decays
Abstract

Decay spectroscopy of the long-lived states in 186Tl has been performed at the ISOLDE Decay Station at ISOLDE, CERN. The α decay from the low-spin (2−) state in 186Tl was observed for the first time and a half-life of 3.4+0.5−0.4 s was determined. Based on the α-decay energy, the relative positions of the long-lived states were fixed, with the (2−) state as the ground state, the 7(+) state at 77(56) keV, and the 10(−) state at 451(56) keV. The level scheme of the internal decay of the 186Tl(10(−)) state [T1/2=3.40(9) s], which was known to decay solely through emission of 374-keV γ-ray transition, was extended and a lower limit for the β-decay branching bβ>5.9(3)% was determined. The extracted retardation factors for the γ decay of the 10(−) state were compared to the available data in neighboring odd-odd thallium isotopes indicating the importance of the πd3/2 shell in the isomeric decay and significant structure differences between 184Tl and 186Tl. peerReviewed

Published
2020

20. Decay studies of the long-lived states in Tl-186

Author

Stryjczyk, M., Andel, B., Andreyev, A. N., Cubiss, J., Pakarinen, J., Rezynkina, K., Van Duppen, P., Antalic, S., Berry, T., Borge, M. J. G., Clisu, C., Cox, D. M., De Witte, H., Fraile, L. M., Fynbo, H. O. U., Gaffney, L. P., Harkness-Brennan, L. J., Huyse, M., Illana, A., Judson, D. S., Konki, J., Kurcewicz, J., Lazarus, I, Lica, R., Madurga, M., Marginean, N., Marginean, R., Mihai, C., Mosat, P., Nacher, E., Negret, A., Ojala, J., Ovejas, J. D., Page, R. D., Papadakis, P., Pascu, S., Perea, A., Podolyak, Zs, Pucknell, V, Rapisarda, E., Rotaru, F., Sotty, C., Tengblad, O., Vedia, V., Vinals, S., Wadsworth, R., Warr, N., Wrzosek-Lipska, K., Stryjczyk, M., Andel, B., Andreyev, A. N., Cubiss, J., Pakarinen, J., Rezynkina, K., Van Duppen, P., Antalic, S., Berry, T., Borge, M. J. G., Clisu, C., Cox, D. M., De Witte, H., Fraile, L. M., Fynbo, H. O. U., Gaffney, L. P., Harkness-Brennan, L. J., Huyse, M., Illana, A., Judson, D. S., Konki, J., Kurcewicz, J., Lazarus, I, Lica, R., Madurga, M., Marginean, N., Marginean, R., Mihai, C., Mosat, P., Nacher, E., Negret, A., Ojala, J., Ovejas, J. D., Page, R. D., Papadakis, P., Pascu, S., Perea, A., Podolyak, Zs, Pucknell, V, Rapisarda, E., Rotaru, F., Sotty, C., Tengblad, O., Vedia, V., Vinals, S., Wadsworth, R., Warr, N., and Wrzosek-Lipska, K.

Abstract

Decay spectroscopy of the long-lived states in Tl-186 has been performed at the ISOLDE Decay Station at ISOLDE, CERN. The a decay from the low-spin (2(-)) state in Tl-186 was observed for the first time and a half-life of 3.4(-0.)(4)(+0.5) s was determined. Based on the alpha-decay energy, the relative positions of the long-lived states were fixed, with the (2(-)) state as the ground state, the 7((+)) state at 77(56) keV, and the 10((-)) state at 451(56) keV. The level scheme of the internal decay of the Tl-186(10((-))) state [T-1/2 = 3.40(9) s], which was known to decay solely through emission of 374-keV gamma-ray transition, was extended and a lower limit for the beta-decay branching b(beta) > 5.9(3)% was determined. The extracted retardation factors for the gamma decay of the 10((-) )state were compared to the available data in neighboring odd-odd thallium isotopes indicating the importance of the pi d(3/2) shell in the isomeric decay and significant structure differences between Tl-184 and Tl-186.

Published
2020

21. The experiments to determine the electron capture and ß-decay of 8B into the highly excited states of 8Be.

Author

Ministerio de Economía y Competitividad (España), European Commission, Víñals, S., García Borge, María José, Tengblad, Olof, Nácher, Enrique, Benito, J., Figuera, P., Fraile, Luis M., Fynbo, H.O.U., Gad, A., Jensen, J., Jonson, B., Lică, R., Marroquín, I., Munch, M., Nilsson, T., Ovejas, J. D., Perea, Ángel, Riisager, K., Smain, S., Sotty, C., Ministerio de Economía y Competitividad (España), European Commission, Víñals, S., García Borge, María José, Tengblad, Olof, Nácher, Enrique, Benito, J., Figuera, P., Fraile, Luis M., Fynbo, H.O.U., Gad, A., Jensen, J., Jonson, B., Lică, R., Marroquín, I., Munch, M., Nilsson, T., Ovejas, J. D., Perea, Ángel, Riisager, K., Smain, S., and Sotty, C.

Abstract

The main goal of this work is to study the structure of the highest energy states in 8Be populated following the ß+-decay and the electron capture (EC) of 8B. With this aim, two experiments were performed at ISOLDE-CERN in 2017 and 2018. The first experiment had the aim to resolve the 2+ doublet at 16.6 and 16.9 MeV, in order to study their isospin mixing. The second experiment aimed to determine a value or give an experimental upper limit to the branching ratio of the exotic EC-p decay. In this paper, we present the experimental setups and we discuss the analysis and present the preliminary results obtained so far.

Published
2020

22. Study of the scattering of 15C at energies around the Coulomb barrier.

Author

Consejo Superior de Investigaciones Científicas (España), Ministerio de Ciencia, Innovación y Universidades (España), Ministerio de Economía y Competitividad (España), Fundação para a Ciência e a Tecnologia (Portugal), European Commission, Universidad Nacional Autónoma de México, Ovejas, J. D., Knyazev, A., Martel, Ismael, Tengblad, Olof, García Borge, María José, Cederkall, J., Keeley, N., Rusek, K., García-Ramos, C., Pérez, T., Acosta, L.A., Arokiaraj, A.A., Babo, M., Cap, T., Ceylan, N., Angelis, G. de, Pietro, A. di, Fernández, J.P., Figuera, P., Fraile, Luis M., Fynbo, H., Galaviz, D., Jensen, J.H., Jonson, B., Kotak, R., Kurtukian-Nieto, T., Madurga, Miguel, Marquínez-Durán, G., Munch, M., Orduz, A.K., Honório, R., Pakou, A., Peralta, L., Perea, Ángel, Raabe, R., Renaud, M., Riisager, K., Sánchez-Benítez, A.M., Sánchez-Segovia, J., Sgouros, O., Soukeras, V., Teubig, P., Víñals, S., Wolinska-Cichocka, M., Wolski, R., Yang, J., Consejo Superior de Investigaciones Científicas (España), Ministerio de Ciencia, Innovación y Universidades (España), Ministerio de Economía y Competitividad (España), Fundação para a Ciência e a Tecnologia (Portugal), European Commission, Universidad Nacional Autónoma de México, Ovejas, J. D., Knyazev, A., Martel, Ismael, Tengblad, Olof, García Borge, María José, Cederkall, J., Keeley, N., Rusek, K., García-Ramos, C., Pérez, T., Acosta, L.A., Arokiaraj, A.A., Babo, M., Cap, T., Ceylan, N., Angelis, G. de, Pietro, A. di, Fernández, J.P., Figuera, P., Fraile, Luis M., Fynbo, H., Galaviz, D., Jensen, J.H., Jonson, B., Kotak, R., Kurtukian-Nieto, T., Madurga, Miguel, Marquínez-Durán, G., Munch, M., Orduz, A.K., Honório, R., Pakou, A., Peralta, L., Perea, Ángel, Raabe, R., Renaud, M., Riisager, K., Sánchez-Benítez, A.M., Sánchez-Segovia, J., Sgouros, O., Soukeras, V., Teubig, P., Víñals, S., Wolinska-Cichocka, M., Wolski, R., and Yang, J.

Abstract

The neutron rich carbon isotope 15C is the only known case of an almost "pure" 2s1/2 single-neutron halo ground state configuration. At collision energies around the Coulomb barrier the reaction dynamics is expected to be dominated by single neutron transfer and breakup. To investigate these effects, we have measured the scattering of 15C with a 208Pb target at 65 MeV at the HIE-ISOLDE facility in CERN (Geneva, Switzerland). The preliminary data demonstrates the presence of a strong long-range absorption pattern in the angular distribution of the elastic cross section. The results are discussed in the framework of Optical Model calculations.

Published
2020

23. The most accurate determination of the 8B half-life

Author

Ministerio de Economía y Competitividad (España), European Commission, Viñals, S., Nácher, Enrique, Tengblad, Olof, Benito, J., García Borge, María José, Figuera, P., Fraile, Luis M., Fynbo, H.O.U., Gad, A., Jensen, J., Jonson, B., Lică, R., Marroquín, I., Munch, M., Nilsson, T., Ovejas, J. D., Perea, Ángel, Riisager, K., Smain, S., Sotty, C., Ministerio de Economía y Competitividad (España), European Commission, Viñals, S., Nácher, Enrique, Tengblad, Olof, Benito, J., García Borge, María José, Figuera, P., Fraile, Luis M., Fynbo, H.O.U., Gad, A., Jensen, J., Jonson, B., Lică, R., Marroquín, I., Munch, M., Nilsson, T., Ovejas, J. D., Perea, Ángel, Riisager, K., Smain, S., and Sotty, C.

Abstract

Beta decay is a primary source of information of the structure of a nucleus. An accurate measurement of the half-life of a nucleus is essential for the proper determination of the reduced Gammow-Teller transition probability B(GT). In this work, we present an experiment using a compact set-up of Si-telescope detectors to measure the half-life of the B nucleus. Three independent measurements have been analysed, obtaining the values 771.9(17) ms, 773.9(18) ms, and 770.9(27) ms. The value of the half-life obtained as the weighted averaged with the previous published measures is 771.17(94) ms which is a factor 3.2 of improvement in the uncertainty of the half-life.

Published
2020

24. Halo effects in the low-energy scattering of 15C with heavy targets

Author

European Organization for Nuclear Research, Ministerio de Economía y Competitividad (España), Ministerio de Ciencia, Innovación y Universidades (España), European Commission, Ovejas, J. D., Knyazev, A., Martel, Ismael, Tengblad, Olof, García Borge, María José, Cederkäll, J., Keeley, N., Rusek, K., García-Ramos, C., Acosta, L.A., Arokiaraj, A.A., Babo, M., Cap, T., Ceylan, N., Angelis, G. de, Pietro, A. di, Fernández, J.P., Figuera, P., Fraile, Luis M., Fynbo, H., Galaviz, D., Jensen, J.H., Jonson, B., Kotak, R., Kurtukian-Nieto, T., Madurga, Miguel, Marquínez-Durán, G., Munch, M., Orduz, A.K., Honório, R., Pakou, A., Pérez, T., Peralta, L., Perea, Ángel, Raabe, R., Renaud, M., Riisager, K., Sánchez-Benítez, A.M., Sánchez-Segovia, J., Sgouros, O., Soukeras, V., Teubig, P., Viñals, S., Wolinska-Cichocka, M., Wolski, R., Yang, J., European Organization for Nuclear Research, Ministerio de Economía y Competitividad (España), Ministerio de Ciencia, Innovación y Universidades (España), European Commission, Ovejas, J. D., Knyazev, A., Martel, Ismael, Tengblad, Olof, García Borge, María José, Cederkäll, J., Keeley, N., Rusek, K., García-Ramos, C., Acosta, L.A., Arokiaraj, A.A., Babo, M., Cap, T., Ceylan, N., Angelis, G. de, Pietro, A. di, Fernández, J.P., Figuera, P., Fraile, Luis M., Fynbo, H., Galaviz, D., Jensen, J.H., Jonson, B., Kotak, R., Kurtukian-Nieto, T., Madurga, Miguel, Marquínez-Durán, G., Munch, M., Orduz, A.K., Honório, R., Pakou, A., Pérez, T., Peralta, L., Perea, Ángel, Raabe, R., Renaud, M., Riisager, K., Sánchez-Benítez, A.M., Sánchez-Segovia, J., Sgouros, O., Soukeras, V., Teubig, P., Viñals, S., Wolinska-Cichocka, M., Wolski, R., and Yang, J.

Abstract

The neutron-rich carbon isotope C was postulated to be a halo nucleus (S = 1215 keV, S = 9395 keV) according to different high-energy experiments. If so, it would be the only halo nucleus exhibiting a "pure" s-wave structure of the ground state. At low collision energies, the effect of this halo structure should manifest as a strong absorption pattern in the angular distribution of the elastic cross section, with a total suppression of the nuclear rainbow due to the large neutron transfer and breakup probabilities, enhanced by the halo configuration. The IS619 experiment, carried out at the HIE-ISOLDE facility at CERN (Switzerland), is the first dynamical study of this nucleus at energies around the Coulomb barrier. It aims to probe the halo structure via the measurement of the elastic cross section on a high-Z Pb target. Preliminary results of the elastic cross section are discussed and compared to Optical Model calculations.

Published
2020

25. Measurement of the 2+ -> 0+ ground-state transition in the beta decay of 20F

Author

Kirsebom, O. S., Hukkanen, M., Kankainen, A., Trzaska, W. H., Stroemberg, D. F., Martinez-Pined, G., Andersen, K., Bodewits, E., Brown, B. A., Canete, L., Cederkall, J., Enqvist, T., Eronen, T., Fynbo, H. O. U., Geldhof, S., de Groote, R., Jenkins, D. G., Jokinen, A., Joshi, P., Khanam, A., Kostensalo, J., Kuusiniemi, P., Langanke, K., Moore, D, Munch, M., Nesterenko, D. A., Ovejas, J. D., Penalla, H., Pohjalainen, L., Reponen, M., Rinta-Antila, S., Riisager, K., de Roubin, A., Schotanus, P., Srivastava, P. C., Suhonen, J., Swartz, J. A., Tengblad, O., Vilen, M., Vinals, S., and Aysto, J.

Subjects
ELEMENTS
Abstract

We report the first detection of the second-forbidden, nonunique, 2(+) -> 0(+), ground-state transition in the beta decay of F-20. A low-energy, mass-separated F-20(+) beam produced at the IGISOL facility in Jyvaskyla, Finland, was implanted in a thin carbon foil and the beta spectrum measured using a magnetic transporter and a plastic-scintillator detector. The beta-decay branching ratio inferred from the measurement is b(beta) = [0.41 +/- 0.08(stat) +/- 0.07(sys)] x 10(-5) corresponding to log ft = 10.89(11), making this one of the strongest second-forbidden, nonunique beta transitions ever measured. The experimental result is supported by shell-model calculations and has significant implications for the final evolution of stars that develop degenerate oxygen-neon cores. Using the new experimental data, we argue that the astrophysical electron-capture rate on Ne-20 is now known to within better than 25% at the relevant temperatures and densities.

Published
2019

26. Measurement of the 2+→0+ ground-state transition in the β decay of F 20

Author

Kirsebom, O. S., Hukkanen, M., Kankainen, A., Trzaska, W. H., Strömberg, D. F., Martínez-Pinedo, G., Andersen, K., Bodewits, E., Brown, B. A., Canete, L., Cederkäll, J., Enqvist, T., Eronen, T., Fynbo, H. O.U., Geldhof, S., De Groote, R., Jenkins, D. G., Jokinen, A., Joshi, P., Khanam, A., Kostensalo, J., Kuusiniemi, P., Langanke, K., Moore, I., Munch, M., Nesterenko, D. A., Ovejas, J. D., Penttilä, H., Pohjalainen, I., Reponen, M., Rinta-Antila, S., Riisager, K., De Roubin, A., Schotanus, P., Srivastava, P. C., Suhonen, J., Swartz, J. A., Tengblad, O., Vilen, M., Vínals, S., Aÿstö, J., Dalhousie University, University of Jyväskylä, GSI Helmholtzzentrum Schwerionenforschung, Aarhus University, SCIONIX Holland BV, Michigan State University, Lund University, University of Oulu, University of York, Department of Applied Physics, Consejo Superior de Investigaciones Cientificas (CSIC), Indian Institute of Technology System, Aalto-yliopisto, and Aalto University

Subjects
ELEMENTS, High Energy Physics::Experiment
Abstract

openaire: EC/H2020/654002/EU//ENSAR2 We report the first detection of the second-forbidden, nonunique, 2(+) -> 0(+), ground-state transition in the beta decay of F-20. A low-energy, mass-separated F-20(+) beam produced at the IGISOL facility in Jyvaskyla, Finland, was implanted in a thin carbon foil and the beta spectrum measured using a magnetic transporter and a plastic-scintillator detector. The beta-decay branching ratio inferred from the measurement is b(beta) = [0.41 +/- 0.08(stat) +/- 0.07(sys)] x 10(-5) corresponding to log ft = 10.89(11), making this one of the strongest second-forbidden, nonunique beta transitions ever measured. The experimental result is supported by shell-model calculations and has significant implications for the final evolution of stars that develop degenerate oxygen-neon cores. Using the new experimental data, we argue that the astrophysical electron-capture rate on Ne-20 is now known to within better than 25% at the relevant temperatures and densities.

Published
2019

28. Transfer and breakup reactions involving 7Be at ISOLDE

Author

Ali, Sk. M., Gupta, D., Kundalia, Kabita, Saha, Swapan K., Tengblad, Olof, Ovejas, J. D., Perea, Ángel, Martel, Ismael, Cederkall, Joakim, Park, Joochun, and Szwec, Stuart

Abstract

CERN Europe/Zurich, 5-6 diciembre 2019

Published
2019

29. Study of the scattering of 15C at energies around the Coulomb barrier

Author

Ovejas, J D, primary, Knyazev, A, additional, Martel, I, additional, Tengblad, O, additional, Borge, M J G, additional, Cederkall, J, additional, Keeley, N, additional, Rusek, K, additional, García-Ramos, C, additional, Pérez, T, additional, Acosta, L A, additional, Arokiaraj, A A, additional, Babo, M, additional, Cap, T, additional, Ceylan, N, additional, Angelis, G De, additional, Pietro, A Di, additional, Fernández, J P, additional, Figuera, P, additional, Fraile, L, additional, Fynbo, H, additional, Galaviz, D, additional, Jensen, J H, additional, Jonson, B, additional, Kotak, R, additional, Kurtukian, T, additional, Madurga, M, additional, Marquínez-Durán, G, additional, Munch, M, additional, Orduz, A K, additional, Honório, R, additional, Pakou, A, additional, Peralta, L, additional, Perea, A, additional, Raabe, R, additional, Renaud, M, additional, Riisager, K, additional, Sánchez-Benítez, A M, additional, Sánchez-Segovia, J, additional, Sgouros, O, additional, Soukeras, V, additional, Teubig, P, additional, Viñals, S, additional, Wolinska-Cichocka, M, additional, Wolski, R, additional, and Yang, J, additional

Published
2020
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30. The experiments to determine the electron capture and β-decay of 8B into the highly excited states of 8Be

Author

Viñals, S, primary, Borge, M J G, additional, Tengblad, O, additional, Nácher, E, additional, Benito, J, additional, Figuera, P, additional, Fraile, L M, additional, Fynbo, H O U, additional, Gad, A, additional, Jensen, J, additional, Jonson, B, additional, Lica, R, additional, Marroquín, I, additional, Munch, M, additional, Nilsson, T, additional, Ovejas, J D, additional, Perea, A, additional, Riisager, K, additional, Smain, S, additional, and Sotty, C, additional

Published
2020
Full Text
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31. Measurement of the 2+→0+ ground-state transition in the β decay of F20

Author

Kirsebom, O. S., primary, Hukkanen, M., additional, Kankainen, A., additional, Trzaska, W. H., additional, Strömberg, D. F., additional, Martínez-Pinedo, G., additional, Andersen, K., additional, Bodewits, E., additional, Brown, B. A., additional, Canete, L., additional, Cederkäll, J., additional, Enqvist, T., additional, Eronen, T., additional, Fynbo, H. O. U., additional, Geldhof, S., additional, de Groote, R., additional, Jenkins, D. G., additional, Jokinen, A., additional, Joshi, P., additional, Khanam, A., additional, Kostensalo, J., additional, Kuusiniemi, P., additional, Langanke, K., additional, Moore, I., additional, Munch, M., additional, Nesterenko, D. A., additional, Ovejas, J. D., additional, Penttilä, H., additional, Pohjalainen, I., additional, Reponen, M., additional, Rinta-Antila, S., additional, Riisager, K., additional, de Roubin, A., additional, Schotanus, P., additional, Srivastava, P. C., additional, Suhonen, J., additional, Swartz, J. A., additional, Tengblad, O., additional, Vilen, M., additional, Vínals, S., additional, and Äystö, J., additional

Published
2019
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32. Electron Capture of 8B into highly excited states of 8Be

Author

García Borge, María José, Víñals, S., Gad, A., Figuera, P., Fraile, L., Fynbo, H., Jensen, J., Jonson, B., Lică, R., Marroquín, I., Munch, M., Nácher, Enrique, Nilsson, T., Ovejas, J. D., Perea, Ángel, Refsgaard, J., Riisager, K., Sotty, C., and Tengblad, Olof

Abstract

INPC 2019, Scottish Event Campus, Glasgow, UK, 29 July – 2 August 2019. -- http://inpc2019.iopconfs.org/home

Published
2019

34. Measurement of the 2$^+$ → 0$^+$ ground-state transition in the β decay of $^{20}$F

Author

Kirsebom, O. S., Hukkanen, M., Cederkäll, J., Enqvist, T., Eronen, T., Fynbo, H. O. U., Geldhof, S., de Groote, R., Jenkins, D. G., Jokinen, A., Joshi, P., Khanam, A., Kankainen, A., Kostensalo, J., Kuusiniemi, P., Langanke, K., Moore, I., Munch, M., Nesterenko, D. A., Ovejas, J. D., Penttilä, H., Pohjalainen, I., Reponen, M., Trzaska, W. H., Rinta-Antila, S., Riisager, K., de Roubin, A., Schotanus, P., Srivastava, P. C., Suhonen, J., Swartz, J. A., Tengblad, O., Vilen, M., Vínals, S., Strömberg, D. F., Äystö, J., Martínez-Pinedo, G., Andersen, K., Bodewits, E., Brown, B. A., and Canete, L.

Subjects
ddc:530
Published
2019

36. Resonance excitations in the $^{7}$Be + d experiment at CERN ISOLDE

Author

Ali, Sk M, Gupta, D, Kundalia, K, Saha, Swapan K, Tengblad, O, Ovejas, J D, Perea, A, Martel, I, Cederkall, J, Park, J, and Szwec, S

Subjects
Nuclear Physics - Theory, Nuclear Physics - Experiment
Abstract

The Big Bang Nucleosynthesis (BBN) theory has been very successful in predicting the observed abundances of light elements like $^2$H, ${3,4}$He. There is, however, a serious discrepancy of a factor of about four in the observed abundance of $^7$Li as compared to that predicted by the BBN theory [1−2]. The high precision measurement of the baryon to photon ratio η by the Wilkinson Microwave Anisotropy Probe (WMAP) and recent observations of metal poor halo stars shows that the $^7$Li abundance predicted by the BBN theory is about $5.12 \times 10^{10}$, whereas the observed value is about $1.23 \times 10^{10}$. This anomaly has been unsolved for decades and is well known. Several avenues have been searched for a solution, of which the resonance excitations in reactions with $^7$Be appear to be very attractive [3].

Published
2019

37. Elastic scattering of p-halo 8B beam close to the Coulomb barrier

Author

Sparta, Roberta, Figuera, P., Pietro, A. di, Tengblad, Olof, Fernández-García, J. P., Acosta-Sánchez, Luis Armando, Bjorn, Jonson, García Borge, María José, Bruni, Giovanni, Davison, Thomas, Ovejas, J. D., Fraile, Luis M., Galaviz, D., Halkjaer Jensen, Jesper, La Cognata, Marco, Martel, Ismael, Perea, Ángel, Sánchez-Benítez, Ángel, Soic, Neven, and Víñals, S.

Abstract

CERN Europe/Zurich, 5-6 diciembre 2019

Published
2019

38. Measurement of the 2+→0+ ground-state transition in the β decay of 20F

Author

Kirsebom, O. S., Hukkanen, M., Kankainen, A., Trzaska, W. H., Strömberg, D. F., Martínez-Pinedo, G., Andersen, K., Bodewits, E., Brown, B. A., Canete, L., Cederkäll, J., Enqvist, T., Eronen, T., Fynbo, H. O. U., Geldhof, S., de Groote, R., Jenkins, D. G., Jokinen, A., Joshi, P., Khanam, A., Kostensalo, J., Kuusiniemi, P., Langanke, K., Moore, I., Munch, M., Nesterenko, D. A., Ovejas, J. D., Penttilä, H., Pohjalainen, I., Reponen, M., Rinta-Antila, S., Riisager, K., de Roubin, A., Schotanus, P., Srivastava, P. C., Suhonen, J., Swartz, J. A., Tengblad, O., Vilen, M., Vínals, S., and Äystö, J.

Subjects
High Energy Physics::Experiment, ydinfysiikka
Abstract

We report the first detection of the second-forbidden, nonunique, 2+→0+, ground-state transition in the β decay of 20F. A low-energy, mass-separated 20F+ beam produced at the IGISOL facility in Jyväskylä, Finland, was implanted in a thin carbon foil and the β spectrum measured using a magnetic transporter and a plastic-scintillator detector. The β-decay branching ratio inferred from the measurement is bβ=[0.41±0.08(stat)±0.07(sys)]×10−5 corresponding to logft=10.89(11), making this one of the strongest second-forbidden, nonunique β transitions ever measured. The experimental result is supported by shell-model calculations and has significant implications for the final evolution of stars that develop degenerate oxygen-neon cores. Using the new experimental data, we argue that the astrophysical electron-capture rate on 20Ne is now known to within better than 25% at the relevant temperatures and densities. peerReviewed

Published
2019

39. Searching for ß-delayed protons from 11 Be

Author

Sokolowska, Natalia Anna, García Borge, María José, Ciemny, Aleksandra, Dominik, W., Fijalkowska, A., Fraile, L.M., Giska, Amanda, Janas, Z., Janiak, U., Kaminski, G., Korgul, A. B., Kubiela, Adam, Mazzocchi, Ch., Miernik, K., Pfutzner, M. L., Pomorski, Marcin, and Ovejas, J. D.

Abstract

ISOLDE Workshop and Usersmeeting. Wednesday 05 December - Friday 07 December 2018 .CERN ( ISOLDE User Support. PH Departmen - CERN/CH-1211 Geneve 23). --.https://indico.cern.ch/event/736872/contributions/

Published
2018

40. Near Coulomb barrier scattering of 15C on 208Pb

Author

Ovejas, J. D.

Abstract

International Scientific Meeting on Nuclear Physics. 18th-22th June, La Rábida, Huelva. (Spain) (2018). Basic concepts in Nuclear Physics: theory, experiments, and applications. -. http://institucional.us.es/rabida/index.php/home-mainmenu-1

Published
2018

41. HALO EFFECTS IN THE LOW-ENERGY SCATTERING OF 15C WITH HEAVY TARGETS.

Author

OVEJAS, J. D., KNYAZEV, A., MARTEL, I., TENGBLAD, O., BORGE, M. J. G., CEDERKÄLL, J., KEELEY, N., RUSEK, K., GARCÍA-RAMOS, C., ACOSTA, L. A., AROKIARAJ, A. A., BABO, M., CAP, T., CEYLAN, N., DE ANGELIS, G., DI PIETRO, A., FERNÁNDEZ, J. P., FIGUERA, P., FRAILE, L., and FYNBO, H.

Subjects
*CARBON isotopes, *NEUTRONS, *RAINBOWS
Abstract

The neutron-rich carbon isotope 15C was postulated to be a halo nucleus (Sn = 1215 keV, S2n = 9395 keV) according to different high-energy experiments. If so, it would be the only halo nucleus exhibiting a “pure” s-wave structure of the ground state. At low collision energies, the effect of this halo structure should manifest as a strong absorption pattern in the angular distribution of the elastic cross section, with a total suppression of the nuclear rainbow due to the large neutron transfer and breakup probabilities, enhanced by the halo configuration. The IS619 experiment, carried out at the HIE-ISOLDE facility at CERN (Switzerland), is the first dynamical study of this nucleus at energies around the Coulomb barrier. It aims to probe the halo structure via the measurement of the elastic cross section on a high-Z 208Pb target. Preliminary results of the elastic cross section are discussed and compared to Optical Model calculations. [ABSTRACT FROM AUTHOR]

Published
2020
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42. THE MOST ACCURATE DETERMINATION OF THE 8B HALF-LIFE.

Author

VIÑALS, S., NÁCHER, E., TENGBLAD, O., BENITO, J., BORGE, M. J. G., FIGUERA, P., FRAILE, L. M., FYNBO, H. O. U., GAD, A., JENSEN, J., JONSON, B., LICA, R., MARROQUÍN, I., MUNCH, M., NILSSON, T., OVEJAS, J. D., PEREA, A., RIISAGER, K., SMAIN, S., and SOTTY, C.

Subjects
BETA decay, INFORMATION resources, DETECTORS
Abstract

Beta decay is a primary source of information of the structure of a nucleus. An accurate measurement of the half-life of a nucleus is essential for the proper determination of the reduced Gammow–Teller transition probability B(GT). In this work, we present an experiment using a compact set-up of Si-telescope detectors to measure the half-life of the 8B nucleus. Three independent measurements have been analysed, obtaining the values 771.9(17) ms, 773.9(18) ms, and 770.9(27) ms. The value of the half-life obtained as the weighted averaged with the previous published measures is 771.17(94) ms which is a factor 3.2 of improvement in the uncertainty of the half-life. [ABSTRACT FROM AUTHOR]

Published
2020
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