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11 results on '"A.J. Boston"'

1. Pairing-quadrupole interplay in the neutron-deficient tin nuclei: First lifetime measurements of low-lying states in 106,108Sn

Author

M. Siciliano, J.J. Valiente-Dobón, A. Goasduff, F. Nowacki, A.P. Zuker, D. Bazzacco, A. Lopez-Martens, E. Clément, G. Benzoni, T. Braunroth, F.C.L. Crespi, N. Cieplicka-Oryńczak, M. Doncel, S. Ertürk, G. de France, C. Fransen, A. Gadea, G. Georgiev, A. Goldkuhle, U. Jakobsson, G. Jaworski, P.R. John, I. Kuti, A. Lemasson, T. Marchi, D. Mengoni, C. Michelagnoli, T. Mijatović, C. Müller-Gatermann, D.R. Napoli, J. Nyberg, M. Palacz, R.M. Pérez-Vidal, B. Sayği, D. Sohler, S. Szilner, D. Testov, M. Zielińska, D. Barrientos, B. Birkenbach, H.C. Boston, A.J. Boston, B. Cederwall, J. Collado, D.M. Cullen, P. Désesquelles, C. Domingo-Pardo, J. Dudouet, J. Eberth, F.J. Egea-Canet, V. González, L.J. Harkness-Brennan, H. Hess, D.S. Judson, A. Jungclaus, W. Korten, M. Labiche, A. Lefevre, S. Leoni, H. Li, A. Maj, R. Menegazzo, B. Million, A. Pullia, F. Recchia, P. Reiter, M.D. Salsac, E. Sanchis, O. Stezowski, and Ch. Theisen

Subjects
Lifetime, Nuclear structure, Multi-nucleon transfer, Light Sn, Tracking array, Physics, QC1-999
Abstract

The lifetimes of the low-lying excited states 2+ and 4+ have been directly measured in the neutron-deficient 106,108Sn isotopes. The nuclei were populated via a deep-inelastic reaction and the lifetime measurement was performed employing a differential plunger device. The emitted γ rays were detected by the AGATA array, while the reaction products were uniquely identified by the VAMOS++ magnetic spectrometer. Large-Scale Shell-Model calculations with realistic forces indicate that, independently of the pairing content of the interaction, the quadrupole force is dominant in the B(E2;21+→0g.s.+) values and it describes well the experimental pattern for 104−114Sn; the B(E2;41+→21+) values, measured here for the first time, depend critically on a delicate pairing-quadrupole balance, disclosed by the very precise results in 108Sn.

Published
2020
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2. Evidence of octupole-phonons at high spin in 207Pb

Author

D. Ralet, E. Clément, G. Georgiev, A.E. Stuchbery, M. Rejmund, P. Van Isacker, G. de France, A. Lemasson, J. Ljungvall, C. Michelagnoli, A. Navin, D.L. Balabanski, L. Atanasova, A. Blazhev, G. Bocchi, R. Carroll, J. Dudouet, E. Dupont, B. Fornal, S. Franchoo, C. Fransen, C. Müller-Gatermann, A. Goasduff, A. Gadea, P.R. John, D. Kocheva, T. Konstantinopoulos, A. Korichi, A. Kusoglu, S.M. Lenzi, S. Leoni, R. Lozeva, A. Maj, R. Perez, N. Pietralla, C. Shand, O. Stezowski, D. Wilmsen, D. Yordanov, D. Barrientos, P. Bednarczyk, B. Birkenbach, A.J. Boston, H.C. Boston, I. Burrows, B. Cederwall, M. Ciemala, J. Collado, F. Crespi, D. Cullen, H.J. Eberth, J. Goupil, L. Harkness, H. Hess, A. Jungclaus, W. Korten, M. Labiche, R. Menegazzo, D. Mengoni, B. Million, J. Nyberg, Zs. Podolyák, A. Pullia, B. Quintana Arnés, F. Recchia, P. Reiter, F. Saillant, M.D. Salsac, E. Sanchis, C. Theisen, J.J. Valiente Dobon, and O. Wieland

Subjects
Physics, QC1-999
Abstract

A lifetime measurement of the 19/2− state in 207Pb has been performed using the Recoil Distance Doppler-Shift (RDDS) method. The nuclei of interest were produced in multi-nucleon transfer reactions induced by a 208Pb beam impinging on a 100Mo enriched target. The beam-like nuclei were detected and identified in terms of their atomic mass number in the VAMOS++ spectrometer while the prompt γ rays were detected by the AGATA tracking array. The measured large reduced transition probability B(E3,19/2−→13/2+)=40(8) W.u. is the first indication of the octupole phonon at high spin in 207Pb. An analysis in terms of a particle-octupole-vibration coupling model indicates that the measured B(E3) value in 207Pb is compatible with the contributions from single-phonon and single particle E3 as well as E3 strength arising from the double-octupole-phonon 6+ state, all adding coherently. A crucial aspect of the coupling model, namely the strong mixing between single-hole and the phonon-hole states, is confirmed in a realistic shell-model calculation. Keywords: AGATA spectrometer, γ-Ray tracking, VAMOS++ spectrometer, Plunger device, Nuclear deformation, Octupole phonon

Published
2019
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3. Isospin dependence of electromagnetic transition strengths among an isobaric triplet

Author

A. Boso, S.A. Milne, M.A. Bentley, F. Recchia, S.M. Lenzi, D. Rudolph, M. Labiche, X. Pereira-Lopez, S. Afara, F. Ameil, T. Arici, S. Aydin, M. Axiotis, D. Barrientos, G. Benzoni, B. Birkenbach, A.J. Boston, H.C. Boston, P. Boutachkov, A. Bracco, A.M. Bruce, B. Bruyneel, B. Cederwall, E. Clement, M.L. Cortes, D.M. Cullen, P. Désesquelles, Zs. Dombràdi, C. Domingo-Pardo, J. Eberth, C. Fahlander, M. Gelain, V. González, P.R. John, J. Gerl, P. Golubev, M. Górska, A. Gottardo, T. Grahn, L. Grassi, T. Habermann, L.J. Harkness-Brennan, T.W. Henry, H. Hess, I. Kojouharov, W. Korten, N. Lalović, M. Lettmann, C. Lizarazo, C. Louchart-Henning, R. Menegazzo, D. Mengoni, E. Merchan, C. Michelagnoli, B. Million, V. Modamio, T. Moeller, D.R. Napoli, J. Nyberg, B.S. Nara Singh, H. Pai, N. Pietralla, S. Pietri, Zs. Podolyak, R.M. Perez Vidal, A. Pullia, D. Ralet, G. Rainovski, M. Reese, P. Reiter, M.D. Salsac, E. Sanchis, L.G. Sarmiento, H. Schaffner, L.M. Scruton, P.P. Singh, C. Stahl, S. Uthayakumaar, J.J. Valiente-Dobón, and O. Wieland

Subjects
Physics, QC1-999
Abstract

Electric quadrupole matrix elements, Mp, for the Jπ=2+→0+, ΔT=0, T=1 transitions across the A=46 isobaric multiplet 46Cr-46V-46Ti have been measured at GSI with the FRS-LYCCA-AGATA setup. This allows direct insight into the isospin purity of the states of interest by testing the linearity of Mp with respect to Tz. Pairs of nuclei in the T=1 triplet were studied using identical reaction mechanisms in order to control systematic errors. The Mp values were obtained with two different methodologies: (i) a relativistic Coulomb excitation experiment was performed for 46Cr and 46Ti; (ii) a “stretched target” technique was adopted here, for the first time, for lifetime measurements in 46V and 46Ti. A constant value of Mp across the triplet has been observed. Shell-model calculations performed within the fp shell fail to reproduce this unexpected trend, pointing towards the need of a wider valence space. This result is confirmed by the good agreement with experimental data achieved with an interaction which allows excitations from the underlying sd shell. A test of the linearity rule for all published data on complete T=1 isospin triplets is presented.

Published
2019
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4. Shell evolution approaching the N=20 island of inversion: Structure of 26Na

Author

G.L. Wilson, W.N. Catford, N.A. Orr, C.Aa. Diget, A. Matta, G. Hackman, S.J. Williams, I.C. Celik, N.L. Achouri, H. Al Falou, R. Ashley, R.A.E. Austin, G.C. Ball, J.C. Blackmon, A.J. Boston, H.C. Boston, S.M. Brown, D.S. Cross, M. Djongolov, T.E. Drake, U. Hager, S.P. Fox, B.R. Fulton, N. Galinski, A.B. Garnsworthy, D. Jamieson, R. Kanungo, K.G. Leach, J.N. Orce, C.J. Pearson, M. Porter-Peden, F. Sarazin, E.C. Simpson, S. Sjue, D. Smalley, C. Sumithrarachchi, S. Triambak, C. Unsworth, and R. Wadsworth

Subjects
81V35, Nuclear structure, 26Na, γ-Ray transitions, Transfer reactions, Shell migration, Physics, QC1-999
Abstract

The levels in 26Na with single particle character have been observed for the first time using the d(25Na, pγ) reaction at 5 MeV/nucleon. The measured excitation energies and the deduced spectroscopic factors are in good overall agreement with (0+1)ħω shell model calculations performed in a complete spsdfp basis and incorporating a reduction in the N=20 gap. Notably, the 1p3/2 neutron configuration was found to play an enhanced role in the structure of the low-lying negative parity states in 26Na, compared to the isotone 28Al. Thus, the lowering of the 1p3/2 orbital relative to the 0f7/2 occurring in the neighbouring Z=10 and 12 nuclei – 25,27Ne and 27,29Mg – is seen also to occur at Z=11 and further strengthens the constraints on the modelling of the transition into the island of inversion.

Published
2016
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9. The use of EXOGAM for in-beam spectroscopy of proton drip-line nuclei with radioactive ion beams

Author

M. Petri, E.S. Paul, P.J. Nolan, A.J. Boston, H.C. Boston, R.J. Cooper, M.R. Dimmock, S. Gros, B.M. McGuirk, G. Turk, D. Guinet, Ph. Lautesse, M. Meyer, N. Redon, B. Rossé, Ch. Schmitt, O. Stézowski, S. Bhattacharyya, G. De France, G. Mukherjee, F. Rejmund, H. Savajols, J.N. Scheurer, J. Gál, J. Molnár, B.M. Nyakó, J. Timár, L. Zolnai, K. Juhász, A. Astier, I. Deloncle, M.G. Porquet, A. Prévost, V.F.E. Pucknell, R. Wadsworth, P. Joshi, G. La Rana, R. Moro, M. Trotta, E. Vardaci, G. Hackman, G.C. Ball, Oliver Lodge Laboratory, University of Liverpool, Institut de Physique Nucléaire de Lyon (IPNL), Centre National de la Recherche Scientifique (CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), Grand Accélérateur National d'Ions Lourds (GANIL), Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), Centre d'Etudes Nucléaires de Bordeaux Gradignan (CENBG), Université Sciences et Technologies - Bordeaux 1-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Institute for Nuclear Research and Nuclear Energy, Bulgarian Academy of Sciences (BAS), Department of Information Technology, University of Debrecen, Centre de Spectrométrie Nucléaire et de Spectrométrie de Masse (CSNSM), Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Sud - Paris 11 (UP11), STFC Daresbury Laboratory, Daresbury Laboratory, Department of Physics, University of York [York, UK], Istituto Nazionale di Fisica Nucleare, Sezione di Napoli (INFN, Sezione di Napoli), Istituto Nazionale di Fisica Nucleare (INFN), TRIUMF [Vancouver], EXOGAM, M., Petri, E. S., Paul, P. J., Nolan, A. J., Boston, H. C., Boston, R. J., Cooper, M. R., Dimmock, S., Gro, B. M., Mcguirk, G., Turk, D., Guinet, Lautesse, P. h., M., Meyer, N., Redon, B., Rossé, Schmitt, C. h., O., Stézowski, S., Bhattacharyya, G., De France, G., Mukherjee, F., Rejmund, H., Savajol, J. N., Scheurer, J., Gál, J., Molnár, B. M., Nyakó, J., Timár, L., Zolnai, K., Juhász, A., Astier, I., Deloncle, M. G., Porquet, A., Prévost, V. F. E., Pucknell, R., Wadsworth, P., Joshi, LA RANA, Giovanni, Moro, RENATA EMILIA MARIA, M., Trotta, Vardaci, Emanuele, G., Hackman, G. C. B. a. l., L., Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Université Sciences et Technologies - Bordeaux 1 (UB)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), University of Debrecen Egyetem [Debrecen], and Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Radioactive ion beams, Nuclear and High Energy Physics, Proton, Fizikai tudományok, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], 01 natural sciences, DIAMANT, Nuclear physics, EXOGAM, Recoil, Természettudományok, 0103 physical sciences, proton drip-line nuclei, 010306 general physics, Spectroscopy, Nuclear Experiment, Instrumentation, Line (formation), Physics, in-beam spectroscopy, Spectrometer, 010308 nuclear & particles physics, DIAMANT array of CsI charged-particle detectors, VAMOS, Physics::Accelerator Physics, Segmented Clover germanium detector, Linear polarisation, Atomic physics, Radioactive ion beam, EXOGAM array of HPGe detectors, Beam (structure)
Abstract

International audience; One of the first fusion–evaporation experiments using radioactive ion beams was performed at GANIL in order to study proton-rich nuclei of the light rare-earth region. The low production cross-section of the exotic species of interest, in combination with the low intensity of the beam and its induced background, demanded the use of a highly efficient experimental setup. This consisted of the EXOGAM γ-ray spectrometer coupled for the first time with both the DIAMANT charged-particle array and the VAMOS recoil spectrometer. In this report the experimental challenges of such studies will be discussed and the experimental achievements of the in-beam spectroscopy of proton drip-line nuclei using EXOGAM will be presented.

Published
2009

10. Application of the Broad Energy Germanium detector: A technique for elucidating β -decay schemes which involve daughter nuclei with very low energy excited states

Author

M. Venhart, D. S. Judson, M. Sedlák, Adarsh Patel, L. J. Harkness-Brennan, Kristian Petrík, J. L. Wood, M. Veselský, Š. Motyčák, Vladislav Matoušek, A.J. Boston, R.-D. Herzberg, R. D. Page, Thomas Elias Cocolios, D. T. Joss, and J. Kliman

Subjects
Physics, Nuclear and High Energy Physics, Large Hadron Collider, Isotope, 010308 nuclear & particles physics, Detector, chemistry.chemical_element, Germanium, 01 natural sciences, Semiconductor detector, Nuclear physics, chemistry, Excited state, 0103 physical sciences, Density of states, Physics::Accelerator Physics, High Energy Physics::Experiment, Atomic physics, Nuclear Experiment, 010306 general physics, Instrumentation, Excitation
Abstract

A technique for elucidating β -decay schemes of isotopes with a large density of states at low excitation energy has been developed, in which a Broad Energy Germanium (BEGe) detector is used in conjunction with coaxial hyper-pure germanium detectors. The power of this technique is demonstrated using the example of 183 Hg decay. Mass-separated samples of 183 Hg were produced by a deposition of the low-energy radioactive-ion beam delivered by the ISOLDE facility at CERN. The excellent energy resolution of the BEGe detector allowed γ -ray energies to be determined with a precision of a few tens of eV, which was sufficient for the analysis of the Rydberg-Ritz combinations (in conjunction with γ - γ coincidences) in the level scheme. The timestamped structure of the data was used for unambiguous separation of γ rays arising from the decay of 183 Hg from those due to the daughter decays.

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11. Characterisation of an AGATA symmetric prototype detector

Author

L. Nelson, H. C. Boston, Matthew Richard Dimmock, C. Parisel, P. J. Nolan, C. Santos, J.R. Cresswell, I.H. Lazarus, P. Medina, J. Simpson, A. J. Boston, Département Recherches Subatomiques (DRS-IPHC), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Louis Pasteur - Strasbourg I-Centre National de la Recherche Scientifique (CNRS), A.J. Boston, J. Vossebeld, P.P. Allport, P.J. Nolan and C.J. Hall, and AGATA

Subjects
Nuclear and High Energy Physics, Photon, Physics::Instrumentation and Detectors, [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], computer.software_genre, Tracking (particle physics), 01 natural sciences, 07.85.Nc, 29.30.-h, 29.30.Kv, 29.40.Gx, Collimated light, PSA, Optics, γ Ray tracking, 0103 physical sciences, Digital acquisition, 010306 general physics, Instrumentation, Physics, Digital electronics, 010308 nuclear & particles physics, business.industry, Detector, HPGe detectors, Simulation software, Pulse (physics), E-field simulation, AGATA, business, computer
Abstract

International audience; The Advanced GAmma Tracking Array (AGATA) symmetric prototype detector has been tested at the University of Liverpool. A 137Ce source, collimated to a 2 mm diameter, was scanned across the front face of the detector and data were acquired utilising digital electronics. Pulse shapes from a selection of well-defined photon interaction positions have been analysed to investigate the position sensitivity of the detector. Furthermore, the application of the electric field simulation software, Multi Geometry Simulation (MGS) to generate theoretical pulse shapes for AGATA detectors has been presented.

Published
2005

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