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20 results on '"Boston AJ"'

1. Evolution of structure and shapes in Er158 to ultrahigh spin

Author

Simpson, J, Riley, MA, Pipidis, A, Paul, ES, Wang, X, Nolan, PJ, Sharpey-Schafer, JF, Aguilar, A, Appelbe, DE, Ayangeakaa, AD, Boston, AJ, Boston, HC, Campbell, DB, Carpenter, MP, Chiara, CJ, Choy, PTW, Clark, RM, Cromaz, M, Evans, AO, Fallon, P, Garg, U, Görgen, A, Hartley, DJ, Janssens, RVF, Joss, DT, Judson, DS, Kondev, FG, Lauritsen, T, Lee, IY, Macchiavelli, AO, Matta, JT, Ollier, J, Petri, M, Revill, JP, Riedinger, LL, Rigby, SV, Teal, C, Twin, PJ, Unsworth, C, Ward, D, Zhu, S, and Ragnarsson, I

Subjects
Nuclear and Plasma Physics, Synchrotrons and Accelerators, Physical Sciences, Nuclear and plasma physics
Abstract

The level structure of Er158 has been studied using the Gammasphere spectrometer via the Cd114(Ca48,4n) reaction at 215 MeV with both thin (self-supporting) and thick (backed) targets. The level scheme has been considerably extended with more than 200 new transitions and six new rotational structures, including two strongly coupled high-K bands. Configuration assignments for the new structures are based on their observed alignments, B(M1)/B(E2) ratios of reduced transition probabilities, excitation energies, and comparisons with neighboring nuclei and theoretical calculations. With increasing angular momentum, this nucleus exhibits Coriolis-induced alignments of both neutrons and protons before it then undergoes a rotation-induced transition from near-prolate collective rotation to a noncollective oblate configuration. This transition occurs via the mechanism of band termination around spin 45ħ in three rotational structures. Two distinct lifetime branches, consistent with the crossing of a collective "fast"rotational structure by an energetically favored "slow"terminating sequence, are confirmed for the positive-parity states, and similar behavior is established in the negative-parity states. Weak-intensity, high-energy transitions are observed to feed into the terminating states. At the highest spins, three collective bands with high dynamic moments of inertia and large quadrupole moments were identified. These bands are interpreted as triaxial strongly deformed structures and mark a return to collectivity at ultrahigh spin.

Published
2023

3. Evidence of Partial Seniority Conservation in the $\pi{g}_{9/2}$ Shell for the $N=50$ Isotones

Author

Perez-Vidal, Rm, Gadea, A, Domingo-Pardo, C, Gargano, A, Valiente-Dobon, Jj, Clement, E, Lemasson, A, Coraggio, L, Siciliano, M, Szilner, S, Bast, M, Braunroth, T, Collado, J, Corina, A, Dewald, A, Doncel, M, Dudouet, J, de France, G, Fransen, C, Gonzalez, V, Huyuk, T, Jacquot, B, John, Pr, Jungclaus, A, Kim, Yh, Korichi, A, Labiche, M, Lenzi, S, Li, H, Ljungvall, J, Lopez-Martens, A, Mengoni, D, Michelagnoli, C, Muller-Gatermann, C, Napoli, Dr, Navin, A, Quintana, B, Ramos, D, Rejmund, M, Sanchis, E, Simpson, J, Stezowski, O, Wilmsen, D, Zielinska, M, Boston, Aj, Barrientos, D, Bednarczyk, P, Benzoni, G, Birkenbach, B, Boston, Hc, Bracco, A, Cederwall, B, Cullen, Dm, Didierjean, F, Eberth, J, Gottardo, A, Goupil, J, Harkness-Brennan, Lj, Hess, H, Judson, Ds, Kaskas, A, Korten, W, Leoni, S, Menegazzo, R, Million, B, Nyberg, J, Podolyak, Z, Pullia, A, Ralet, D, Recchia, F, Reiter, P, Rezynkina, K, Salsac, Md, Senyigit, M, Sohler, D, Theisen, C, Verney, D, Grand Accélérateur National d'Ions Lourds (GANIL), 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), Institut de Physique des 2 Infinis de Lyon (IP2I Lyon), 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), Institut Laue-Langevin (ILL), Laboratoire de Physique des 2 Infinis Irène Joliot-Curie (IJCLab), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, Institut Pluridisciplinaire Hubert Curien (IPHC), and Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Subatomär fysik, [PHYS.NUCL]Physics [physics]/Nuclear Theory [nucl-th], Nuclear Physics - Theory, Atom and Molecular Physics and Optics, Subatomic Physics, Atom- och molekylfysik och optik
Abstract

International audience; The reduced transition probabilities for the $4^+_1 \to 2^+_1$ and $2^+_1 \to 0^+_1$ transitions in $^{92}$Mo and $^{94}$Ru and for the $4^+_1 \to 2^+_1$ and $6^+_1 \to 4^+_1$ transitions in $^{90}$Zr have been determined in this experiment making use of a multinucleon transfer reaction. These results have been interpreted on the basis of realistic shell-model calculations in the $f_{5/2}, p_{3/2}, p_{1/2},$ and $g_{9/2}$ proton valence space. Only the combination of extensive lifetime information and large scale shell-model calculations allowed the extent of the seniority conservation in the $N=50 g_{9/2}$ orbital to be understood. The conclusion is that seniority is largely conserved in the first $\pi{g}_{9/2}$ orbital.

Published
2022

4. Evidence for enhanced neutron-proton correlations from the level structure of the N = Z+1 nucleus Tc-87(43)44

Author

Liu, X, Cederwall, B, Qi, C, Wyss, RA, Aktas, O, Ertoprak, A, Zhang, W, Clement, E, de France, G, Ralet, D, Gadea, A, Goasduff, A, Jaworski, G, Kuti, I, Nyako, BM, Nyberg, J, Palacz, M, Wadsworth, R, Valiente-Dobon, JJ, Al-Azri, H, Nyberg, A Atac, Back, T, de Angelis, G, Doncel, M, Dudouet, J, Gottardo, A, Jurado, M, Ljungvall, J, Mengoni, D, Napoli, DR, Petrache, CM, Sohler, D, Timar, J, Barrientos, D, Bednarczyk, P, Benzoni, G, Birkenbach, B, Boston, AJ, Boston, HC, Burrows, I, Charles, L, Ciemala, M, Crespi, FCL, Cullen, DM, Desesquelles, P, Domingo-Pardo, C, Eberth, J, Erduran, N, Erturk, S, Gonzalez, V, Goupil, J, Hess, H, Huyuk, T, Jungclaus, A, Korten, W, Lemasson, A, Leoni, S, Maj, A, Menegazzo, R, Million, B, Perez-Vidal, RM, Podolyak, Zs, Pullia, A, Recchia, F, Reiter, P, Saillant, F, Salsac, MD, Sanchis, E, Simpson, J, Stezowski, O, Theisen, C, and Zielinska, M

Published
2021

6. Nuclear structure of Au-181 studied via beta(+)/EC decay of Hg-181 at ISOLDE

Author

Sedlak, M, Venhart, M, Wood, JL, Matousek, V, Balogh, M, Boston, AJ, Cocolios, TE, Harkness-Brennan, LJ, Herzberg, R-D, Joss, DT, Judson, DS, Kliman, J, Page, RD, Patel, A, Petrik, K, and Veselsky, M

Subjects
RELEASE, Science & Technology, Physics, ALPHA-DECAY, Physics, Particles & Fields, ENERGY, Physics, Nuclear, EXCITED-STATES, SPIN, SHAPE COEXISTENCE, Physical Sciences, BETA-DECAY, PARTICLE, DATA SHEETS, TRANSITION
Abstract

ispartof: EUROPEAN PHYSICAL JOURNAL A vol:56 issue:6 status: published

Published
2020

7. Delayed or absent pi(h(11/2))(2) alignment in Xe-111

Author

Capponi, L, Smith, JF, Ruotsalainen, P, Scholey, C, Rahkila, P, Bianco, L, Boston, AJ, Boston, HC, Cullen, DM, Derkx, X, Drummond, MC, Grahn, T, Greenlees, PT, Grocutt, L, Hadinia, B, Jakobsson, U, Joss, DT, Julin, R, Juutinen, S, Labiche, M, Leino, M, Leach, KG, McPeake, C, Mulholland, KF, Nieminen, P, O'Donnell, D, Pa, ES ul, Peura, P, Sandzelius, M, Saren, J, Saygi, B, Sorri, J, Stolze, S, Thornthwaite, A, Taylor, MJ, and Uusitalo, J

Published
2020

8. Lifetime measurements in Ti-52,Ti-54 to study shell evolution toward N=32

Author

Goldkuhle, A, Fransen, C, Blazhev, A, Beckers, M, Birkenbach, B, Braunroth, T, Clement, E, Dewald, A, Dudouet, J, Eberth, J, Hess, H, Jacquot, B, Jolie, J, Kim, Y-H, Lemasson, A, Lenzi, SM, Li, HJ, Litzinger, J, Michelagnoli, C, Mueller-Gatermann, C, Singh, BS Nara, Perez-Vidal, RM, Ralet, D, Reiter, P, Vogt, A, Warr, N, Zell, KO, Atac, A, Barrientos, D, Barthe-Dejean, C, Benzoni, G, Boston, AJ, Boston, HC, Bourgault, P, Burrows, I, Cacitti, J, Cederwall, B, Ciemala, M, Cullen, DM, De France, G, Domingo-Pardo, C, Foucher, J-L, Fremont, G, Gadea, A, Gangnant, P, Gonzalez, V, Goupil, J, Henrich, C, Houarner, C, Jean, M, Judson, DS, Korichi, A, Korten, W, Labiche, M, Lefevre, A, Legeard, L, Legruel, F, Leoni, S, Ljungvall, J, Maj, A, Maugeais, C, Menager, L, Menard, N, Menegazzo, R, Mengoni, D, Million, B, Munoz, H, Napoli, DR, Navin, A, Nyberg, J, Ozille, M, Podolyak, Zs, Pullia, A, Raine, B, Recchia, F, Ropert, J, Saillant, F, Salsac, MD, Sanchis, E, Schmitt, C, Simpson, J, Spitaels, C, Stezowski, O, Theisen, Ch, Toulemonde, M, Tripon, M, Dobon, J-J Valiente, Voltolini, G, Zielinska, M, and Collaboration, AGATA

Published
2019

9. Spectroscopy of Hf-161 from low to high spin

Author

Mason, PJR, Simpson, J, Paul, ES, Riley, MA, Auranen, K, Badran, H, Baron, JS, Boston, AJ, Davis-Merry, T, Grahn, T, Greenlees, PT, Herzan, A, Jakobsson, U, Joss, DT, Julin, R, Juutinen, S, Konki, J, Leino, M, McPeake, C, Miller, SL, O'Neill, G, Pakarinen, J, Papadakis, P, Partanen, J, Peura, P, Rahkila, P, Ruotsalainen, P, Sandzelius, M, Saren, J, Scholey, C, Sharpey-Schafer, JF, Sinclair, L, Sorri, J, Stolze, S, Uusitalo, J, Villafani, K, Wearing, F, and Wright, JP

Published
2014

10. STRUCTURE OF Na-26 VIA A NOVEL TECHNIQUE USING (d, p gamma) WITH A RADIOACTIVE Na-25 BEAM

Author

Catford, WN, Celik, IC, Wilson, GL, Matta, A, Orr, NA, Diget, CA, Adsley, P, Al-Falou, H, Ashley, R, Austin, RAE, Ball, GC, Blackmon, JC, Boston, AJ, Boston, HC, Brown, SM, Cross, DS, Djongolov, M, Drake, TE, Hager, U, Fox, SP, Fulton, BR, Galinski, N, Garnsworthy, AB, Hackman, G, Jamieson, D, Kanungo, R, Leach, K, Martin, J-P, Orce, JN, Pearson, CJ, Porter-Peden, M, Sarazin, F, Sjue, S, Sumithrarachchi, C, Svensson, CE, Triambak, S, Unsworth, C, Wadsworth, R, Williams, SJ, Catford, WN, Celik, IC, Wilson, GL, Matta, A, Orr, NA, Diget, CA, Adsley, P, Al-Falou, H, Ashley, R, Austin, RAE, Ball, GC, Blackmon, JC, Boston, AJ, Boston, HC, Brown, SM, Cross, DS, Djongolov, M, Drake, TE, Hager, U, Fox, SP, Fulton, BR, Galinski, N, Garnsworthy, AB, Hackman, G, Jamieson, D, Kanungo, R, Leach, K, Martin, J-P, Orce, JN, Pearson, CJ, Porter-Peden, M, Sarazin, F, Sjue, S, Sumithrarachchi, C, Svensson, CE, Triambak, S, Unsworth, C, Wadsworth, R, and Williams, SJ

Abstract

States in 26Na were populated in the (d, pγ) reaction, induced by bombarding deuterium target nuclei with an intense reaccelerated beam of 25Na ions from the ISAC2 accelerator at TRIUMF. Gamma-rays were recorded in coincidence with protons and used to extract differential cross sections for 21 states up to the neutron decay threshold of 5 MeV. Results for levels below 3 MeV are discussed in detail and compared with shell model calculations and with previous work. The angular distributions of decay gamma-rays were measured for individual states and are compared to theoretically calculated distributions, highlighting some issues for future work.

Published
2015

11. Towards Na via (d,p) with SHARC and TIGRESS and a novel zero-degree detector

Author

Wilson, GL, Catford, Wilton, Brown, SM, Diget, CA, Adsley, P, Fox, SP, Fulton, BR, Wadsworth, R, Orr, NA, Al-Falou, H, Ball, GC, Churchman, RM, Cross, DS, Dech, J, Djongolov, M, Hager, U, Galinski, N, Garnsworthy, AB, Hackman, G, Orce, JN, Pearson, CJ, Sjue, S, Sumithrarachchi, C, Triambak, S, Williams, SJ, Ashley, R, Boston, AJ, Boston, HJ, Unsworth, C, Austin, RAE, Kanungo, R, Blackmon, JC, Chen, AA, Chen, J, Drake, TE, Martin, J-P, Porter-Peden, M, Sarazin, F, Jamieson, D, Leach, K, and Svensson, CE

Subjects
Nuclear Experiment
Abstract

Nucleon transfer experiments have in recent years begun to be exploited in the study of nuclei far from stability, using radioactive beams in inverse kinematics. New techniques are still being developed in order to perform these experiments. The present experiment is designed to study the odd-odd nucleus Na which has a high density of states and therefore requires gamma-ray detection to distinguish between them. The experiment employed an intense beam of up to 3×10 pps of Na at 5.0 MeV/nucleon from the ISAC-II facility at triumf. The new silicon array SHARC was used for the first time and was coupled to the segmented clover gamma-ray array TIGRESS. A novel thin plastic scintillator detector was employed at zero degrees to identify and reject reactions occurring on the carbon component of the (CD) target. The efficiency of the background rejection using this detector is described with respect to the proton and gamma-ray spectra from the (d,p) reaction. © Published under licence by IOP Publishing Ltd.

Published
2012

12. Storage ring at HIE-ISOLDE: Technical design report: Technical design report

Author

Grieser, M, Litvinov, YA, Raabe, R, Blaum, K, Blumenfeld, Y, Butler, PA, Wenander, F, Woods, PJ, Aliotta, M, Andreyev, A, Artemyev, A, Atanasov, D, Aumann, T, Balabanski, D, Barzakh, A, Batist, L, Bernardes, A-P, Bernhardt, D, Billowes, J, Bishop, S, Borge, M, Borzov, I, Bosch, F, Boston, AJ, Brandau, C, Catford, W, Catherall, R, Cederkäll, J, Cullen, D, Davinson, T, Dillmann, I, Dimopoulou, C, Dracoulis, G, Düllmann, CE, Egelhof, P, Estrade, A, Fischer, D, Flanagan, K, Fraile, L, Fraser, MA, Freeman, SJ, Geissel, H, Gerl, J, Greenlees, P, Grisenti, RE, Habs, D, von Hahn, R, Hagmann, S, Hausmann, M, He, JJ, Heil, M, Huyse, M, Jenkins, D, Jokinen, A, Jonson, B, Joss, DT, Kadi, Y, Kalantar-Nayestanaki, N, Kay, BP, Kiselev, O, Kluge, H-J, Kowalska, M, Kozhuharov, C, Kreim, S, Kröll, T, Kurcewicz, J, Labiche, M, Lemmon, RC, Lestinsky, M, Lotay, G, Ma, XW, Marta, M, Meng, J, Mücher, D, Mukha, I, Müller, A, Murphy, AS, Neyens, G, Nilsson, T, Nociforo, C, Nörtershäuser, W, Page, RD, Pasini, M, Petridis, N, Pietralla, N, Pfützner, M, Podolyák, Z, Regan, P, Reed, MW, Reifarth, R, Reiter, P, Repnow, R, Riisager, K, Rubio, B, Sanjari, MS, Savin, DW, Scheidenberger, C, Schippers, S, Schneider, D, Schuch, R, Schwalm, D, Schweikhard, L, Shubina, D, Siesling, E, Simon, H, Simpson, J, Smith, J, Sonnabend, K, Steck, M, Stora, T, Stöhlker, T, Sun, B, Surzhykov, A, Suzaki, F, Tarasov, O, Trotsenko, S, Tu, XL, Van Duppen, P, Volpe, C, Voulot, D, Walker, PM, Wildner, E, Winckler, N, Winters, DFA, Wolf, A, Xu, HS, Yakushev, A, Yamaguchi, T, Yuan, YJ, Zhang, YH, and Zuber, K

Subjects
Physics::Accelerator Physics, Nuclear Experiment
Abstract

We propose to install a storage ring at an ISOL-type radioactive beam facility for the first time. Specifically, we intend to setup the heavy-ion, low-energy ring TSR at the HIE-ISOLDE facility in CERN, Geneva. Such a facility will provide a capability for experiments with stored secondary beams that is unique in the world. The envisaged physics programme is rich and varied, spanning from investigations of nuclear ground-state properties and reaction studies of astrophysical relevance, to investigations with highly-charged ions and pure isomeric beams. The TSR might also be employed for removal of isobaric contaminants from stored ion beams and for systematic studies within the neutrino beam programme. In addition to experiments performed using beams recirculating within the ring, cooled beams can also be extracted and exploited by external spectrometers for high-precision measurements. The existing TSR, which is presently in operation at the Max-Planck Institute for Nuclear Physics in Heidelberg, is well-suited and can be employed for this purpose. The physics cases as well as technical details of the existing ring facility and of the beam and infrastructure requirements at HIE-ISOLDE are discussed in the present technical design report.

Published
2012

13. Structure of high-spin states in 100Pd

Author

Perez, GE, Sohler, D, Algora, A, Dombradi, Z, Nyako, BM, Timar, J, Zolnai, L, Wyss, R, Cederkall, J, Johnson, A, Kerek, A, Klamra, W, Norlin, LO, Lipoglavsek, M, Fahlander, C, Likar, A, Palacz, M, Atac, A, Nyberg, J, Persson, J, Gizon, A, Gizon, J, Boston, AJ, Paul, ES, Grawe, H, Schubart, R, Joss, DT, Juutinen, S, Makela, E, Kownacki, J, de Poli, M, Bednarczyk, P, de Angelis, G, Seweryniak, D, Foltescu, D, Roth, HA, Skeppstedt, O, Jerrestam, D, Shizuma, T, Sletten, G, Tormanen, S, Perez, GE, Sohler, D, Algora, A, Dombradi, Z, Nyako, BM, Timar, J, Zolnai, L, Wyss, R, Cederkall, J, Johnson, A, Kerek, A, Klamra, W, Norlin, LO, Lipoglavsek, M, Fahlander, C, Likar, A, Palacz, M, Atac, A, Nyberg, J, Persson, J, Gizon, A, Gizon, J, Boston, AJ, Paul, ES, Grawe, H, Schubart, R, Joss, DT, Juutinen, S, Makela, E, Kownacki, J, de Poli, M, Bednarczyk, P, de Angelis, G, Seweryniak, D, Foltescu, D, Roth, HA, Skeppstedt, O, Jerrestam, D, Shizuma, T, Sletten, G, and Tormanen, S

Published
2001

15. A Study of the Effects of Position Resolution and Energy Resolution on Compton Imaging using a Single Planar Strip Detector

Author

Wright, JP and Boston, AJ

Abstract

The feasibility of single element Compton imaging using a Double Sided Germanium Strip Detector (DSGSD) has been investigated, with potential use in assisting particle identification as part of Phase III DEGAS at DESPEC in mind. DEGAS is a proposed high-purity germanium tracking array for use in the DEcay SPECtroscopy (DESPEC) experiment at FAIR. The concept of γ-ray tracking within a DSGSD has been proved viable, with Compton images reconstructed from partial energy depositions within the detector volume. Using the raw positional information provided by the segmentation of the detector, initial source locations were unable to be resolved, with the resulting image displaying multiple ‘hotspots’ resulting from the selection criteria imposed. The causes of these features have been explored and explained in terms of scattering angles using the simulation package GAMOS. The effects of Pulse Shape Analysis, as a means of improving position sensitivity, have also been investigated, using a simulated database in con- junction with a grid search algorithm. Detailed electric field simulations were created, enabling a simulated pulse shape database to be generated using the ADL software package. Experimental data were sorted to locate potential Compton events, with charge pulses for each events stored using a digital electronics setup. Experimental pulses were compared to pulses from the simulated database using a FoM minimisation grid search algorithm. This improved the position resolution of interactions within the detector, thus improving the effectiveness of the resulting Compton reconstructions. With the application of PSA, initial source positions were located to within ∼ 10 mm, with the image resolution found to be of the order ∼ 100 mm for a range of initial γ-ray energies. Initial results appear promising, with future work required to improve the efficiency of the method. Additionally, Monte Carlo simulations have been performed to study the individual contributions of both energy and position resolution on the final reconstructed Compton image. Simulations were performed for three energy resolutions; 0, 3 and 50 keV, with a fixed position resolution of 2 × 2 × 10 mm, in addition to three position resolutions; 1, 2 and 5 mm3, with a fixed energy resolution of 5 keV. The results of these showed that the position sensitivity of the detector has a much more significant impact of both the location and resolution of the reconstructed Compton image.

16. High-Precision Spectroscopy of ^{20}O Benchmarking Ab Initio Calculations in Light Nuclei.

Author

Zanon I, Clément E, Goasduff A, Menéndez J, Miyagi T, Assié M, Ciemała M, Flavigny F, Lemasson A, Matta A, Ramos D, Rejmund M, Achouri L, Ackermann D, Barrientos D, Beaumel D, Benzoni G, Boston AJ, Boston HC, Bottoni S, Bracco A, Brugnara D, de France G, de Sereville N, Delaunay F, Desesquelles P, Didierjean F, Domingo-Prato C, Dudouet J, Eberth J, Fernández D, Fougères C, Gadea A, Galtarossa F, Girard-Alcindor V, Gonzales V, Gottardo A, Hammache F, Harkness-Brennan LJ, Hess H, Judson DS, Jungclaus A, Kaşkaş A, Kim YH, Kuşoğlu A, Labiche M, Leblond S, Lenain C, Lenzi SM, Leoni S, Li H, Ljungvall J, Lois-Fuentes J, Lopez-Martens A, Maj A, Menegazzo R, Mengoni D, Michelagnoli C, Million B, Napoli DR, Nyberg J, Pasqualato G, Podolyak Z, Pullia A, Quintana B, Recchia F, Regueira-Castro D, Reiter P, Rezynkina K, Rojo JS, Salsac MD, Sanchis E, Şenyiğit M, Siciliano M, Sohler D, Stezowski O, Theisen C, Utepov A, Valiente-Dobón JJ, Verney D, and Zielinska M

Abstract

The excited states of unstable ^{20}O were investigated via γ-ray spectroscopy following the ^{19}O(d,p)^{20}O reaction at 8  AMeV. By exploiting the Doppler shift attenuation method, the lifetimes of the 2_{2}^{+} and 3_{1}^{+} states were firmly established. From the γ-ray branching and E2/M1 mixing ratios for transitions deexciting the 2_{2}^{+} and 3_{1}^{+} states, the B(E2) and B(M1) were determined. Various chiral effective field theory Hamiltonians, describing the nuclear properties beyond ground states, along with a standard USDB interaction, were compared with the experimentally obtained data. Such a comparison for a large set of γ-ray transition probabilities with the valence space in medium similarity renormalization group ab initio calculations was performed for the first time in a nucleus far from stability. It was shown that the ab initio approaches using chiral effective field theory forces are challenged by detailed high-precision spectroscopic properties of nuclei. The reduced transition probabilities were found to be a very constraining test of the performance of the ab initio models.

Published
2023
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17. Search for 22 Na in novae supported by a novel method for measuring femtosecond nuclear lifetimes.

Author

Fougères C, de Oliveira Santos F, José J, Michelagnoli C, Clément E, Kim YH, Lemasson A, Guimarães V, Barrientos D, Bemmerer D, Benzoni G, Boston AJ, Böttger R, Boulay F, Bracco A, Čeliković I, Cederwall B, Ciemala M, Delafosse C, Domingo-Pardo C, Dudouet J, Eberth J, Fülöp Z, González V, Gottardo A, Goupil J, Hess H, Jungclaus A, Kaşkaş A, Korichi A, Lenzi SM, Leoni S, Li H, Ljungvall J, Lopez-Martens A, Menegazzo R, Mengoni D, Million B, Mrázek J, Napoli DR, Navin A, Nyberg J, Podolyák Z, Pullia A, Quintana B, Ralet D, Redon N, Reiter P, Rezynkina K, Saillant F, Salsac MD, Sánchez-Benítez AM, Sanchis E, Şenyiğit M, Siciliano M, Smirnova NA, Sohler D, Stanoiu M, Theisen C, Valiente-Dobón JJ, Ujić P, and Zielińska M

Abstract

Classical novae are thermonuclear explosions in stellar binary systems, and important sources of 26 Al and 22 Na. While γ rays from the decay of the former radioisotope have been observed throughout the Galaxy, 22 Na remains untraceable. Its half-life (2.6 yr) would allow the observation of its 1.275 MeV γ-ray line from a cosmic source. However, the prediction of such an observation requires good knowledge of its nucleosynthesis. The 22 Na(p, γ) 23 Mg reaction remains the only source of large uncertainty about the amount of 22 Na ejected. Its rate is dominated by a single resonance on the short-lived state at 7785.0(7) keV in 23 Mg. Here, we propose a combined analysis of particle-particle correlations and velocity-difference profiles to measure femtosecond nuclear lifetimes. The application of this method to the study of the 23 Mg states, places strong limits on the amount of 22 Na produced in novae and constrains its detectability with future space-borne observatories., (© 2023. This is a U.S. Government work and not under copyright protection in the US; foreign copyright protection may apply.)

Published
2023
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18. Evidence of Partial Seniority Conservation in the πg_{9/2} Shell for the N=50 Isotones.

Author

Pérez-Vidal RM, Gadea A, Domingo-Pardo C, Gargano A, Valiente-Dobón JJ, Clément E, Lemasson A, Coraggio L, Siciliano M, Szilner S, Bast M, Braunroth T, Collado J, Corina A, Dewald A, Doncel M, Dudouet J, de France G, Fransen C, González V, Hüyük T, Jacquot B, John PR, Jungclaus A, Kim YH, Korichi A, Labiche M, Lenzi S, Li H, Ljungvall J, López-Martens A, Mengoni D, Michelagnoli C, Müller-Gatermann C, Napoli DR, Navin A, Quintana B, Ramos D, Rejmund M, Sanchis E, Simpson J, Stezowski O, Wilmsen D, Zielińska M, Boston AJ, Barrientos D, Bednarczyk P, Benzoni G, Birkenbach B, Boston HC, Bracco A, Cederwall B, Cullen DM, Didierjean F, Eberth J, Gottardo A, Goupil J, Harkness-Brennan LJ, Hess H, Judson DS, Kaşkaş A, Korten W, Leoni S, Menegazzo R, Million B, Nyberg J, Podolyak Z, Pullia A, Ralet D, Recchia F, Reiter P, Rezynkina K, Salsac MD, Şenyiğit M, Sohler D, Theisen C, and Verney D

Abstract

The reduced transition probabilities for the 4_{1}^{+}→2_{1}^{+} and 2_{1}^{+}→0_{1}^{+} transitions in ^{92}Mo and ^{94}Ru and for the 4_{1}^{+}→2_{1}^{+} and 6_{1}^{+}→4_{1}^{+} transitions in ^{90}Zr have been determined in this experiment making use of a multinucleon transfer reaction. These results have been interpreted on the basis of realistic shell-model calculations in the f_{5/2}, p_{3/2}, p_{1/2}, and g_{9/2} proton valence space. Only the combination of extensive lifetime information and large scale shell-model calculations allowed the extent of the seniority conservation in the N=50 g_{9/2} orbital to be understood. The conclusion is that seniority is largely conserved in the first πg_{9/2} orbital.

Published
2022
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19. Isospin Properties of Nuclear Pair Correlations from the Level Structure of the Self-Conjugate Nucleus ^{88}Ru.

Author

Cederwall B, Liu X, Aktas Ö, Ertoprak A, Zhang W, Qi C, Clément E, de France G, Ralet D, Gadea A, Goasduff A, Jaworski G, Kuti I, Nyakó BM, Nyberg J, Palacz M, Wadsworth R, Valiente-Dobón JJ, Al-Azri H, Ataç Nyberg A, Bäck T, de Angelis G, Doncel M, Dudouet J, Gottardo A, Jurado M, Ljungvall J, Mengoni D, Napoli DR, Petrache CM, Sohler D, Timár J, Barrientos D, Bednarczyk P, Benzoni G, Birkenbach B, Boston AJ, Boston HC, Burrows I, Charles L, Ciemala M, Crespi FCL, Cullen DM, Désesquelles P, Domingo-Pardo C, Eberth J, Erduran N, Ertürk S, González V, Goupil J, Hess H, Huyuk T, Jungclaus A, Korten W, Lemasson A, Leoni S, Maj A, Menegazzo R, Million B, Perez-Vidal RM, Podolyak Z, Pullia A, Recchia F, Reiter P, Saillant F, Salsac MD, Sanchis E, Simpson J, Stezowski O, Theisen C, and Zielińska M

Abstract

The low-lying energy spectrum of the extremely neutron-deficient self-conjugate (N=Z) nuclide _{44}^{88}Ru_{44} has been measured using the combination of the Advanced Gamma Tracking Array (AGATA) spectrometer, the NEDA and Neutron Wall neutron detector arrays, and the DIAMANT charged particle detector array. Excited states in ^{88}Ru were populated via the ^{54}Fe(^{36}Ar,2nγ)^{88}Ru^{*} fusion-evaporation reaction at the Grand Accélérateur National d'Ions Lourds (GANIL) accelerator complex. The observed γ-ray cascade is assigned to ^{88}Ru using clean prompt γ-γ-2-neutron coincidences in anticoincidence with the detection of charged particles, confirming and extending the previously assigned sequence of low-lying excited states. It is consistent with a moderately deformed rotating system exhibiting a band crossing at a rotational frequency that is significantly higher than standard theoretical predictions with isovector pairing, as well as observations in neighboring N>Z nuclides. The direct observation of such a "delayed" rotational alignment in a deformed N=Z nucleus is in agreement with theoretical predictions related to the presence of strong isoscalar neutron-proton pair correlations.

Published
2020
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20. Pseudospin Symmetry and Microscopic Origin of Shape Coexistence in the ^{78}Ni Region: A Hint from Lifetime Measurements.

Author

Delafosse C, Verney D, Marević P, Gottardo A, Michelagnoli C, Lemasson A, Goasduff A, Ljungvall J, Clément E, Korichi A, De Angelis G, Andreoiu C, Babo M, Boso A, Didierjean F, Dudouet J, Franchoo S, Gadea A, Georgiev G, Ibrahim F, Jacquot B, Konstantinopoulos T, Lenzi SM, Maquart G, Matea I, Mengoni D, Napoli DR, Nikšić T, Olivier L, Pérez-Vidal RM, Portail C, Recchia F, Redon N, Siciliano M, Stefan I, Stezowski O, Vretenar D, Zielinska M, Barrientos D, Benzoni G, Birkenbach B, Boston AJ, Boston HC, Cederwall B, Charles L, Ciemala M, Collado J, Cullen DM, Désesquelles P, de France G, Domingo-Pardo C, Eberth J, González V, Harkness-Brennan LJ, Hess H, Judson DS, Jungclaus A, Korten W, Lefevre A, Legruel F, Menegazzo R, Million B, Nyberg J, Quintana B, Ralet D, Reiter P, Saillant F, Sanchis E, Theisen C, and Valiente Dobon JJ

Abstract

Lifetime measurements of excited states of the light N=52 isotones ^{88}Kr, ^{86}Se, and ^{84}Ge have been performed, using the recoil distance Doppler shift method and VAMOS and AGATA spectrometers for particle identification and gamma spectroscopy, respectively. The reduced electric quadrupole transition probabilities B(E2;2^{+}→0^{+}) and B(E2;4^{+}→2^{+}) were obtained for the first time for the hard-to-reach ^{84}Ge. While the B(E2;2^{+}→0^{+}) values of ^{88}Kr, ^{86}Se saturate the maximum quadrupole collectivity offered by the natural valence (3s, 2d, 1g_{7/2}, 1h_{11/2}) space of an inert ^{78}Ni core, the value obtained for ^{84}Ge largely exceeds it, suggesting that shape coexistence phenomena, previously reported at N≲49, extend beyond N=50. The onset of collectivity at Z=32 is understood as due to a pseudo-SU(3) organization of the proton single-particle sequence reflecting a clear manifestation of pseudospin symmetry. It is realized that the latter provides actually reliable guidance for understanding the observed proton and neutron single particle structure in the whole medium-mass region, from Ni to Sn, pointing towards the important role of the isovector-vector ρ field in shell-structure evolution.

Published
2018
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