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  • 1. Akkoyun, S.
    et al.
    Algora, A.
    Alikhani, B.
    Ameil, F.
    de Angelis, G.
    Arnold, L.
    Astier, A.
    Ataç, Ayşe
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Aubert, Y.
    Aufranc, C.
    Austin, A.
    Aydin, S.
    Azaiez, F.
    Badoer, S.
    Balabanski, D. L.
    Barrientos, D.
    Baulieu, G.
    Baumann, R.
    Bazzacco, D.
    Beck, F. A.
    Beck, T.
    Bednarczyk, P.
    Bellato, M.
    Bentley, M. A.
    Benzoni, G.
    Berthier, R.
    Berti, L.
    Beunard, R.
    Lo Bianco, G.
    Birkenbach, B.
    Bizzeti, P. G.
    Bizzeti-Sona, A. M.
    Le Blanc, F.
    Blasco, J. M.
    Blasi, N.
    Bloor, D.
    Boiano, C.
    Borsato, M.
    Bortolato, D.
    Boston, A. J.
    Boston, H. C.
    Bourgault, P.
    Boutachkov, P.
    Bouty, A.
    Bracco, A.
    Brambilla, S.
    Brawn, I. P.
    Brondi, A.
    Broussard, S.
    Bruyneel, B.
    Bucurescu, D.
    Burrows, I.
    Buerger, A.
    Cabaret, S.
    Cahan, B.
    Calore, E.
    Camera, F.
    Capsoni, A.
    Carrio, F.
    Casati, G.
    Castoldi, M.
    Cederwall, Bo
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Cercus, J. -L
    Chambert, V.
    El Chambit, M.
    Chapman, R.
    Charles, L.
    Chavas, J.
    Clement, E.
    Cocconi, P.
    Coelli, S.
    Coleman-Smith, P. J.
    Colombo, A.
    Colosimo, S.
    Commeaux, C.
    Conventi, D.
    Cooper, R. J.
    Corsi, A.
    Cortesi, A.
    Costa, L.
    Crespi, F. C. L.
    Cresswell, J. R.
    Cullen, D. M.
    Curien, D.
    Czermak, A.
    Delbourg, D.
    Depalo, R.
    Descombes, T.
    Desesquelles, P.
    Detistov, P.
    Diarra, C.
    Didierjean, F.
    Dimmock, M. R.
    Doan, Q. T.
    Domingo-Pardo, C.
    Doncel, M.
    Dorangeville, F.
    Dosme, N.
    Drouen, Y.
    Duchene, G.
    Dulny, B.
    Eberth, J.
    Edelbruck, P.
    Egea, J.
    Engert, T.
    Erduran, M. N.
    Erturk, S.
    Fanin, C.
    Fantinel, S.
    Farnea, E.
    Faul, T.
    Filliger, M.
    Filmer, F.
    Finck, Ch.
    de France, G.
    Gadea, A.
    Gast, W.
    Geraci, A.
    Gerl, J.
    Gernhaeuser, R.
    Giannatiempo, A.
    Giaz, A.
    Gibelin, L.
    Givechev, A.
    Goel, N.
    Gonzalez, V.
    Gottardo, A.
    Grave, X.
    Grebosz, J.
    Griffiths, R.
    Grint, A. N.
    Gros, P.
    Guevara, L.
    Gulmini, M.
    Goergen, A.
    Ha, H. T. M.
    Habermann, T.
    Harkness, L. J.
    Harroch, H.
    Hauschild, K.
    He, C.
    Hernandez-Prieto, A.
    Hervieu, B.
    Hess, H.
    Hueyuek, T.
    Ince, E.
    Isocrate, R.
    Jaworski, G.
    Johnson, Arne
    Jolie, J.
    Jones, P.
    Jonson, B.
    Joshi, P.
    Judson, D. S.
    Jungclaus, A.
    Kaci, M.
    Karkour, N.
    Karolak, M.
    Kaskas, A.
    Kebbiri, M.
    Kempley, R. S.
    Khaplanov, Anton
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Klupp, S.
    Kogimtzis, M.
    Kojouharov, I.
    Korichi, A.
    Korten, W.
    Kroell, Th.
    Kruecken, R.
    Kurz, N.
    Ky, B. Y.
    Labiche, M.
    Lafay, X.
    Lavergne, L.
    Lazarus, I. H.
    Leboutelier, S.
    Lefebvre, F.
    Legay, E.
    Legeard, L.
    Lelli, F.
    Lenzi, S. M.
    Leoni, S.
    Lermitage, A.
    Lersch, D.
    Leske, J.
    Letts, S. C.
    Lhenoret, S.
    Lieder, R. M.
    Linget, D.
    Ljungvall, J.
    Lopez-Martens, A.
    Lotode, A.
    Lunardi, S.
    Maj, A.
    van der Marel, J.
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Mariette, Y.
    Marginean, N.
    Marginean, R.
    Maron, G.
    Mather, A. R.
    Meczynski, W.
    Mendez, V.
    Medina, P.
    Melon, B.
    Menegazzo, R.
    Mengoni, D.
    Merchan, E.
    Mihailescu, L.
    Michelagnoli, C.
    Mierzejewski, J.
    Milechina, Larissa
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Million, B.
    Mitev, K.
    Molini, P.
    Montanari, D.
    Moon, S.
    Morbiducci, F.
    Moro, R.
    Morrall, P. S.
    Moeller, O.
    Nannini, A.
    Napoli, D. R.
    Nelson, L.
    Nespolo, M.
    Ngo, V. L.
    Nicoletto, M.
    Nicolini, R.
    Le Noa, Y.
    Nolan, P. J.
    Norman, M.
    Nyberg, J.
    Obertelli, A.
    Olariu, A.
    Orlandi, R.
    Oxley, D. C.
    Ozben, C.
    Ozille, M.
    Oziol, C.
    Pachoud, E.
    Palacz, M.
    Palin, J.
    Pancin, J.
    Parisel, C.
    Pariset, P.
    Pascovici, G.
    Peghin, R.
    Pellegri, L.
    Perego, A.
    Perrier, S.
    Petcu, M.
    Petkov, P.
    Petrache, C.
    Pierre, E.
    Pietralla, N.
    Pietri, S.
    Pignanelli, M.
    Piqueras, I.
    Podolyak, Z.
    Le Pouhalec, P.
    Pouthas, J.
    Pugnere, D.
    Pucknell, V. F. E.
    Pullia, A.
    Quintana, B.
    Raine, R.
    Rainovski, G.
    Ramina, L.
    Rampazzo, G.
    La Rana, G.
    Rebeschini, M.
    Recchia, F.
    Redon, N.
    Reese, M.
    Reiter, P.
    Regan, P. H.
    Riboldi, S.
    Richer, M.
    Rigato, M.
    Rigby, S.
    Ripamonti, G.
    Robinson, A. P.
    Robin, J.
    Roccaz, J.
    Ropert, J. -A
    Rosse, B.
    Rossi Alvarez, C.
    Rosso, D.
    Rubio, B.
    Rudolph, D.
    Saillant, F.
    Sahin, E.
    Salomon, F.
    Salsac, M. -D
    Salt, J.
    Salvato, G.
    Sampson, J.
    Sanchis, E.
    Santos, C.
    Schaffner, H.
    Schlarb, M.
    Scraggs, D. P.
    Seddon, D.
    Senyigit, M.
    Sigward, M. -H
    Simpson, G.
    Simpson, J.
    Slee, M.
    Smith, J. F.
    Sona, P.
    Sowicki, B.
    Spolaore, P.
    Stahl, C.
    Stanios, T.
    Stefanova, E.
    Stezowski, O.
    Strachan, J.
    Suliman, G.
    Soderstrom, P. -A
    Tain, J. L.
    Tanguy, S.
    Tashenov, Stanislav
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Theisen, Ch.
    Thornhill, J.
    Tomasi, F.
    Toniolo, N.
    Touzery, R.
    Travers, B.
    Triossi, A.
    Tripon, M.
    Tun-Lanoe, K. M. M.
    Turcato, M.
    Unsworth, C.
    Ur, C. A.
    Valiente-Dobon, J. J.
    Vandone, V.
    Vardaci, E.
    Venturelli, R.
    Veronese, F.
    Veyssiere, Ch.
    Viscione, E.
    Wadsworth, R.
    Walker, P. M.
    Warr, N.
    Weber, C.
    Weisshaar, D.
    Wells, D.
    Wieland, O.
    Wiens, A.
    Wittwer, G.
    Wollersheim, H. J.
    Zocca, F.
    Zamfir, N. V.
    Zieblinski, M.
    Zucchiatti, A.
    AGATA-Advanced GAmma Tracking Array2012In: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 668, p. 26-58Article in journal (Refereed)
    Abstract [en]

    The Advanced GAmma Tracking Array (AGATA) is a European project to develop and operate the next generation gamma-ray spectrometer. AGATA is based on the technique of gamma-ray energy tracking in electrically segmented high-purity germanium crystals. This technique requires the accurate determination of the energy, time and position of every interaction as a gamma ray deposits its energy within the detector volume. Reconstruction of the full interaction path results in a detector with very high efficiency and excellent spectral response. The realisation of gamma-ray tracking and AGATA is a result of many technical advances. These include the development of encapsulated highly segmented germanium detectors assembled in a triple cluster detector cryostat, an electronics system with fast digital sampling and a data acquisition system to process the data at a high rate. The full characterisation of the crystals was measured and compared with detector-response simulations. This enabled pulse-shape analysis algorithms, to extract energy, time and position, to be employed. In addition, tracking algorithms for event reconstruction were developed. The first phase of AGATA is now complete and operational in its first physics campaign. In the future AGATA will be moved between laboratories in Europe and operated in a series of campaigns to take advantage of the different beams and facilities available to maximise its science output. The paper reviews all the achievements made in the AGATA project including all the necessary infrastructure to operate and support the spectrometer.

  • 2. Al-Khatib, A.
    et al.
    Singh, A. K.
    Hubel, H.
    Bringel, P.
    Burger, A.
    Neusser, A.
    Schonwasser, G.
    Cederwall, Bo
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Lagergren, Karin
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Gorgen, A.
    et al.,
    High-spin states in Ba-1242005In: Acta Physica Polonica B, ISSN 0587-4254, E-ISSN 1509-5770, Vol. 36, no 4, p. 1029-1032Article in journal (Refereed)
    Abstract [en]

    High-spin states in Ba-124 were populated using the Ni-64 (Ni-64,4n) Ba-124 reaction at beam energies of 255 and 261 MeV. Gamma-ray coincidences were measured using the EUROBALL detector array. The charged-particle detector array DIAMANT provided channel selection. The previously known rotational bands are extended to higher spins. Five new hands are observed, one of them extends up to the spin 40h region.

  • 3. Al-Khatib, A.
    et al.
    Singh, A. K.
    Hubel, H.
    Bringel, P.
    Cederwall, Bo
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Redon, N.
    et al,
    Competition between collective and noncollective excitation modes at high spin in Ba-1242006In: Physical Review C. Nuclear Physics, ISSN 0556-2813, E-ISSN 1089-490X, Vol. 74, no 1Article in journal (Refereed)
    Abstract [en]

    High-spin states in Ba-124 were investigated in two experiments using the Ni-64(Ni-64, 4n)Ba-124 reaction at three different beam energies. In-beam gamma-ray coincidences were measured with the Euroball and Gammasphere detector arrays. In the experiment with Euroball, the CsI detector array Diamant was employed to discriminate against charged-particle channels. Six new rotational bands were observed in Ba-124, and previously known bands were extended to higher spins. One of the bands shows a transition from collective to noncollective behavior at high spins. Configuration assignments are suggested on the basis of comparison with cranked shell model and cranked Nilsson-Strutinsky calculations.

  • 4.
    Andgren, Karin
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Lifetime measurements of excited states in 165Lu and 107Cd2006Licentiate thesis, comprehensive summary (Other scientific)
    Abstract [en]

    Measuring lifetimes of excited nuclear states can give important information on the internal structure of the nucleus. This thesis is based on two experiments performed in Italy and in the USA in order to deduce the lifetimes of excited states in 165Lu and 107Cd. The lifetimes were measured using the Recoil Distance Method and the reduced transition probabilities between states have been calculated from the lifetimes in a model independent way. In the analysis of the data from the experiment on 165Lu, the shape of the nucleus is investigated using a collective rotational model to describe the observed excited states. A possibility of a triaxial shape of this nucleus is discussed. In the second experiment the obtained reduced transition probabilities for the nucleus 107Cd are compared to theoretical predictions for vibrational and rotational excitation modes

  • 5.
    Andgren, Karin
    et al.
    KTH, School of Engineering Sciences (SCI), Physics.
    Cederwall, Bo
    KTH, School of Engineering Sciences (SCI), Physics.
    Bäck, Torbjörn
    KTH, School of Engineering Sciences (SCI), Physics.
    Hadinia, Baharak
    KTH, School of Engineering Sciences (SCI), Physics.
    Johnson, Arne
    KTH, School of Engineering Sciences (SCI), Physics.
    Khaplanov, Anton
    KTH, School of Engineering Sciences (SCI), Physics.
    Sandzelius, Mikael
    KTH, School of Engineering Sciences (SCI), Physics.
    Wyss, Ramon
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    gamma-ray spectroscopy of At-1972008In: Physical Review C. Nuclear Physics, ISSN 0556-2813, E-ISSN 1089-490X, Vol. 78, no 4, p. 044328-1-044328-8Article in journal (Refereed)
    Abstract [en]

    Excited states of the extremely neutron-deficient nucleus At-197 have been studied in an in-beam experiment using the fusion-evaporation reaction Sn-118(Kr-82,p2n)At-197. gamma rays belonging to At-197 feeding the I-pi=(9/2(-)) ground state, as well as gamma rays feeding the 311-keV I-pi=(13/2(+)) isomer, decaying via the emission of gamma rays, and the 52-keV I-pi=(1/2(+)) alpha-decaying isomer have been identified using the recoil-alpha-decay tagging technique. Total Routhian surface calculations predict a near-spherical shape for the (9/2(-)) ground state and oblate shapes with beta(2) around -0.2 for the (1/2(+)) and the (13/2(+)) states. These predictions agree with our experimental findings.

  • 6.
    Andgren, Karin
    et al.
    KTH, School of Engineering Sciences (SCI), Physics.
    Cederwall, Bo
    KTH, School of Engineering Sciences (SCI), Physics.
    Hadinia, Baharak
    KTH, School of Engineering Sciences (SCI), Physics.
    Johnson, Arne
    KTH, School of Engineering Sciences (SCI), Physics.
    Khaplanov, Anton
    KTH, School of Engineering Sciences (SCI), Physics.
    Sandzelius, Mikael
    KTH, School of Engineering Sciences (SCI), Physics.
    Wyss, Ramon
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    et al.,
    Excited states in the neutron-deficient nuclei Rn-197,Rn-199,Rn-2012008In: Physical Review C. Nuclear Physics, ISSN 0556-2813, E-ISSN 1089-490X, Vol. 77, no 5, p. 054303-1-054303-7Article in journal (Refereed)
    Abstract [en]

    Excited states of the extremely neutron-deficient radon isotopes with N = 111, 113, 115 have been studied for the first time in a series of in-beam experiments performed at the Accelerator Laboratory of the University of Jyvaskyla. The reactions used were: Sn-118(Kr-82, 3n)Rn-197, Sn-120(Kr-82, 3n)Rn-199, Sm-150(Cr-52, 3n)Rn-199, and Sn-122(Kr-82, 3n)Rn-201. The gamma rays emitted from excited states in the different isotopes were identified using the recoil-alpha-decay tagging technique. The estimated cross section for the production of Rn-197(m) was 7(3) nb, which is the lowest cross section reported so far for an in-beam study. The energies of the (17/2(+)) levels built on the isomeric (13/2(+)) states in Rn-197,Rn-199,Rn-201 indicate a transition from an anharmonic vibrational structure toward a rotational structure at low spins for these nuclei. However, the transition is not as sharp as predicted by theory.

  • 7. Andreyev, A. N.
    et al.
    Antalic, S.
    Ackermann, D.
    Franchoo, S.
    Hessberger, F. P.
    Hofmann, S.
    Huyse, M.
    Kojouharov, I.
    Kindler, B.
    Kuusiniemi, P.
    Lesher, S. R.
    Lommel, B.
    Mann, R.
    Munzenberg, G.
    Nishio, K.
    Page, R. D.
    Ressler, J. J.
    Streicher, B.
    Saro, S.
    Sulignano, B.
    Van Duppen, P.
    Wiseman, D.
    Wyss, Ramon
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    alpha-decay of the new isotope Po-187: Probing prolate structures beyond the neutron mid-shell at N=1042006In: Physical Review C. Nuclear Physics, ISSN 0556-2813, E-ISSN 1089-490X, Vol. 73, no 4, p. 044324-Article in journal (Refereed)
    Abstract [en]

    The new neutron-deficient isotope Po-187 has been identified in the complete fusion reaction Ti-46+Sm-144 -> Po-187+3n at the velocity filter SHIP. Striking features of the Po-187 alpha decay are the strongly-hindered decay to the spherical ground state and unhindered decay to a surprisingly low-lying deformed excited state at 286 keV in the daughter nucleus Pb-183. Based on the potential energy surface calculations, the Po-187 ground state and the 286 keV excited state in Pb-183 were interpreted as being of prolate origin. The systematic deviation of the alpha-decay properties in the lightest odd-A Po isotopes relative to the smooth behavior in the even-A neighbors is discussed. Improved data for the decay of Bi-187(m,g) were also obtained.

  • 8. Andreyev, A. N.
    et al.
    Antalic, S.
    Huyse, M.
    Van Duppen, P.
    Ackermann, D.
    Bianco, L.
    Cullen, D. M.
    Darby, I. G.
    Franchoo, S.
    Heinz, S.
    Hessberger, F. P.
    Hofmann, S.
    Kojouharov, I.
    Kindler, B.
    Leppanen, A. P.
    Lommel, B.
    Mann, R.
    Muenzenberg, G.
    Pakarinen, J.
    Page, R. D.
    Ressler, J. J.
    Saro, S.
    Streicher, B.
    Sulignano, B.
    Thomson, J.
    Wyss, Ramon
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    alpha decay of the new isotopes Rn-193,Rn-1942006In: Physical Review C. Nuclear Physics, ISSN 0556-2813, E-ISSN 1089-490X, Vol. 74, no 6, p. 064303-Article in journal (Refereed)
    Abstract [en]

    The new neutron-deficient isotopes Rn-193,Rn-194 have been identified in the complete fusion reaction Cr-52+Sm-144 -> Rn-196(*) at the velocity filter SHIP. The alpha-decay energy and half-life value of Rn-194 were determined to be E-alpha=7700(10) keV and T-1/2=0.78(16) ms, respectively. For Rn-193 the half-life of T-1/2=1.15(27) ms and two alpha lines at E-alpha 1=7685(15) keV, I-alpha 1=74(20)% and E-alpha 2=7875(20) keV, I-alpha 2=26(12)% were found. The decay pattern of Rn-193, which is substantially different from that of the heavier odd-A Rn isotopes, provides first experimental evidence for the long-predicted deformation in the very neutron-deficient Rn nuclei.

  • 9. Andreyev, A. N.
    et al.
    Huyse, M.
    Van Duppen, P.
    Qi, Chong
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Liotta, Roberto J.
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Antalic, S.
    Ackermann, D.
    Franchoo, S.
    Heßberger, F. P.
    Hofmann, S.
    Kojouharov, I.
    Kindler, B.
    Kuusiniemi, P.
    Lesher, S. R.
    Lommel, B.
    Mann, R.
    Nishio, K.
    Page, R. D.
    Streicher, B.
    Šáro, Š.
    Sulignano, B.
    Wiseman, D.
    Wyss, Ramon A .
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Signatures of the Z=82 shell closure in alpha-decay process2013In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 110, no 24, article id 242502Article in journal (Refereed)
    Abstract [en]

    In recent experiments at the velocity filter Separator for Heavy Ion reaction Products (SHIP) (GSI, Darmstadt), an extended and improved set of α-decay data for more than 20 of the most neutron-deficient isotopes in the region from lead to thorium was obtained. The combined analysis of this newly available α-decay data, of which the Po186 decay is reported here, allowed us for the first time to clearly show that crossing the Z=82 shell to higher proton numbers strongly accelerates the α decay. From the experimental data, the α-particle formation probabilities are deduced following the Universal Decay Law approach. The formation probabilities are discussed in the framework of the pairing force acting among the protons and the neutrons forming the α particle. A striking resemblance between the phenomenological pairing gap deduced from experimental binding energies and the formation probabilities is noted. These findings support the conjecture that both the N=126 and Z=82 shell closures strongly influence the α-formation probability.

  • 10. Antalic, S.
    et al.
    Andreyev, A. N.
    Ackermann, D.
    Bianco, L.
    Cullen, D.
    Darby, I.
    Franchoo, S.
    Heinz, S.
    Hessberger, F. P.
    Hofmann, S.
    Huyse, M.
    Kindler, B.
    Kojouharov, I.
    Leppanen, A. P.
    Lesher, S. R.
    Lommel, B.
    Mann, R.
    Muenzenberg, G.
    Nishio, K.
    Page, R. D.
    Pakarinen, J.
    Ressler, J. J.
    Saro, S.
    Streicher, B.
    Sulignano, B.
    Thomson, J.
    Van Duppen, P.
    Venhart, M.
    Wiseman, D.
    Wyss, Ramon
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    The new isotopes in Po-Rn region2007In: Acta Physica Polonica B, ISSN 0587-4254, E-ISSN 1509-5770, Vol. 38, no 4, p. 1557-1560Article in journal (Refereed)
    Abstract [en]

    This contribution reviews the results of the recent experiments at the velocity filter SHIP in GSI Darmstadt obtained in the region of neutron deficient isotopes from lead to radon. The data for new very neutron-deficient isotopes Po-187, Rn-193,Rn-194 and their decay properties are presented. The isotopes were produced and identified in the complete fusion reactions Ti-46+Sm-144 -> Po-187+3n and Cr-52+Sm-144 -> Rn-194,Rn-193+2,3n.

  • 11.
    Arzhanov, Alexander
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Gogny-Hartree-Fock-Bogolyubov Nuclear Mass Models with Application to r-Process Stellar Nucleosynthesis2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • 12. Ashley, S. F.
    et al.
    Regan, P. H.
    Andgren, Karin
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    McCutchan, E. A.
    Zamfir, N. V.
    Amon, L.
    Cakirli, R. B.
    Casten, R. F.
    Clark, R. M.
    Gelletly, W.
    Gürdal, G.
    Keyes, K. L.
    Meyer, D. A.
    Erduran, M. N.
    Papenberg, A.
    Pietralla, N.
    Plettner, C.
    Rainovski, G.
    Ribas, R. V.
    Thomas, N. J.
    Vinson, J.
    Warner, D. D.
    Werner, V.
    Williams, E.
    Liu, H. L.
    Xu, F. R.
    Intrinsic state lifetimes in Pd-103 and Cd-106,Cd-1072007In: Physical Review C. Nuclear Physics, ISSN 0556-2813, E-ISSN 1089-490X, Vol. 76, no 6, p. 064302-Article in journal (Refereed)
    Abstract [en]

    The mean-lifetimes, tau, of various medium-spin excited states in Pd-103 and Cd-106,Cd-107 have been deduced using the Recoil Distance Doppler Shift technique and the Differential Decay Curve Method. In Cd-106, the mean-lifetimes of the I-pi=12(+) state at E-x=5418 keV and the I-pi=11(-) state at E-x=4324 keV have been deduced as 11.4(17)ps and 8.2(7)ps, respectively. The associated beta(2) deformation within the axially-symmetric deformed rotor model for these states are 0.14(1) and 0.14(1), respectively. The beta(2) deformation of 0.14(1) for the I-pi=12(+) state in Cd-106 compares with a predicted beta(2) value from total Routhian surface (TRS) calculations of 0.17. In addition, the mean-lifetimes of the yrast I-pi = 15(-)/2 states in Pd-103 (at E-x=1262 keV) and Cd-107 (at E-x=1360 keV) have been deduced to be 31.2(44)ps and 31.4(17)ps, respectively, corresponding to beta(2) values of 0.16(1) and 0.12(1) assuming axial symmetry. Agreement with TRS calculations are good for Pd-103 but deviate for that predicted for Cd-107.

  • 13. Augustyniak, W.
    et al.
    Barion, L.
    Barsov, S.
    Bechstedt, U.
    Benati, P.
    Bertelli, S.
    Carassiti, V.
    Chiladze, D.
    Ciullo, G.
    Contalbrigo, M.
    Dalpiaz, P. F.
    Dymov, S.
    Engels, R.
    Erwen, W.
    Fiorini, M.
    Gaisser, M.
    Gebel, R.
    Goslaswski, P.
    Grigoriev, K.
    Guidoboni, G.
    Kacharava, A.
    Khoukaz, A.
    Kulikov, A.
    Kleines, H.
    Langenberg, G.
    Lehrach, A.
    Lenisa, P.
    Lomidze, N.
    Lorentz, B.
    Macharashvili, G.
    Maier, R.
    Marianski, B.
    Martin, S.
    McHedlishvili, D.
    Merzliakov, S.
    Meshkov, I. N.
    Meyer, H. O.
    Mielke, M.
    Mikirtychiants, M.
    Mikirtychiants, S.
    Nass, A.
    Nekipelov, M.
    Nikolaev, N.
    Nioradze, M.
    Oellers, D.
    Papenbrock, M.
    Pappalardo, L.
    Pesce, A.
    Polyanskiy, A.
    Prasuhn, D.
    Rathmann, F.
    Sarkadi, J.
    Smirnov, A.
    Seyfarth, H.
    Shmakova, V.
    Statera, M.
    Steffens, E.
    Stein, H. J.
    Stockhorst, H.
    Straatman, H.
    Ströher, H.
    Tabidze, M.
    Tagliente, G.
    Thörngren Engblom, Pia
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Trusov, S.
    Trzcinski, A.
    Valdau, Y.
    Vasiliev, A.
    von Würtemberg, K. M.
    Weidemann, C.
    Wüstner, P.
    Zupranski, P.
    Polarization of a stored beam by spin-filtering2012In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 718, no 1, p. 64-69Article in journal (Refereed)
    Abstract [en]

    The PAX Collaboration has successfully performed a spin-filtering experiment with protons at the COSY-ring. The measurement allowed the determination of the spin-dependent polarizing cross section, that compares well with the theoretical prediction from the nucleon-nucleon potential. The test confirms that spin-filtering can be adopted as a method to polarize a stored beam and that the present interpretation of the mechanism in terms of the proton-proton interaction is correct. The outcome of the experiment is of utmost importance in view of the possible application of the method to polarize a beam of stored antiprotons.

  • 14. Backstrom, E.
    et al.
    Gurell, J.
    Royen, P.
    Mannervik, S.
    Norlin, Lars-Olov
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Blackwell-Whitehead, R.
    Hartman, H.
    Nilsson, H.
    The FERRUM project: metastable lifetimes in Cr II2012In: Monthly notices of the Royal Astronomical Society, ISSN 0035-8711, E-ISSN 1365-2966, Vol. 420, no 2, p. 1636-1639Article in journal (Refereed)
    Abstract [en]

    Parity forbidden radiative transitions from metastable levels are observed in spectra of low-density astrophysical plasmas. These lines are used as probes of the physical conditions, made possible due to the long lifetime of their upper level. In a joint effort, the FERRUM project aims to obtain new and accurate atomic data for the iron-group elements, and part of this project concerns forbidden lines. The radiative lifetimes of the metastable energy levels 3 d4(a 3 D)4 s c4 D 5/2 and 3 d4(a 3 D)4 s c4 D 7/2 of singly ionized chromium have been measured. The experiment has been performed at the ion storage ring CRYRING. We employed a laser-probing technique developed for measuring long lifetimes. In this article, we present the lifetimes of these levels to be t5/2= 1.28(16) s and t7/2= 1.37(7) s, respectively. A comparison with previous theoretical work shows good agreement and the result is discussed in a theoretical context.

  • 15. Bagdasarian, Z.
    et al.
    Stephenson, E. J.
    Thörngren Engblom, Pia
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Wuestner, P.
    Measuring the polarization of a rapidly precessing deuteron beam2014In: Physical Review Special Topics. Accelerators and Beams, ISSN 1098-4402, E-ISSN 1098-4402, Vol. 17, no 5, p. 052803-Article in journal (Refereed)
    Abstract [en]

    This paper describes a time-marking system that enables a measurement of the in-plane (horizontal) polarization of a 0.97-GeV/c deuteron beam circulating in the Cooler Synchrotron (COSY) at the Forschungszentrum Julich. The clock time of each polarimeter event is used to unfold the 120-kHz spin precession and assign events to bins according to the direction of the horizontal polarization. After accumulation for one or more seconds, the down-up scattering asymmetry can be calculated for each direction and matched to a sinusoidal function whose magnitude is proportional to the horizontal polarization. This requires prior knowledge of the spin tune or polarization precession rate. An initial estimate is refined by resorting the events as the spin tune is adjusted across a narrow range and searching for the maximum polarization magnitude. The result is biased toward polarization values that are too large, in part because of statistical fluctuations but also because sinusoidal fits to even random data will produce sizable magnitudes when the phase is left free to vary. An analysis procedure is described that matches the time dependence of the horizontal polarization to templates based on emittance-driven polarization loss while correcting for the positive bias. This information will be used to study ways to extend the horizontal polarization lifetime by correcting spin tune spread using ring sextupole fields and thereby to support the feasibility of searching for an intrinsic electric dipole moment using polarized beams in a storage ring. This paper is a combined effort of the Storage Ring EDM collaboration and the JEDI collaboration.

  • 16.
    Ban, Shufang
    et al.
    KTH, School of Engineering Sciences (SCI), Physics.
    Meng, J.
    Satula, W.
    Wyss, Ramon
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Nuclear symmetry energy in relativistic mean field theory2006In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 633, no 2-3, p. 231-236Article in journal (Refereed)
    Abstract [en]

    The physical origin of the nuclear symmetry energy is studied within the relativistic mean field (RMF) theory. Based on the nuclear binding energies calculated with and without mean isovector potential for several isobaric chains we confirm earlier Skyrme-Hartree-Fock result that the nuclear symmetry energy strength depends on the mean level spacing epsilon(A) and an effective mean isovector potential strength K(A). A detailed analysis of the isospin dependence of these two components contributing to the nuclear symmetry energy reveals a quadratic dependence due to the mean-isoscalar potential, similar to epsilon T-2, and, completely unexpectedly, the presence of a strong linear component similar to kappa T(T + 1 + epsilon/kappa) in the isovector potential. The latter generates a nuclear symmetry energy in RMF theory that is proportional to E-sym similar to T(T + 1) at variance to the non-relativistic calculation. The origin of the linear term in RMF theory needs to be further explored.

  • 17.
    Bhagwat, A.
    et al.
    UM DAE Ctr Excellence Basic Sci, Mumbai 400098, Maharashtra, India.;AlbaNova Univ Ctr, Dept Nucl Phys, KTH Royal Inst Technol, S-10691 Stockholm, Sweden..
    Liotta, Roberto
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics. KTH, School of Biotechnology (BIO), Centres, Albanova VinnExcellence Center for Protein Technology, ProNova.
    Cluster emission from superheavy nuclei2018In: European Physical Journal A, ISSN 1434-6001, E-ISSN 1434-601X, Vol. 54, no 11, article id 200Article in journal (Refereed)
    Abstract [en]

    The process leading to cluster emission from superheavy nuclei in the range 100 122 has been systematically investigated. This topic is of importance because it opens up the possibility of identifying superheavy elements through deposition of clusters in the detection system. In this paper we evaluate the cluster decay half lives by considering the cluster as a particle. The motion of this particle in the field induced by the daughter nucleus is determined by solving the corresponding Schrodinger equation imposing outgoing boundary conditions (Gamow state). The corresponding Wood-Saxon potential is fitted to obtain the energies provided by a mass formula that has been established recently to have a very high degree of precision. The resulting expression for the decay width is exact, i.e. no approximation besides the assumption of a preformed cluster is introduced. It is found that the heavy cluster emission probability in the superheavy region is much smaller than the corresponding a emission probability.

  • 18. Bhagwat, A.
    et al.
    Vinas, X.
    Centelles, M.
    Schuck, P.
    Wyss, Ramon
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Microscopic-macroscopic approach for binding energies with the Wigner-Kirkwood method. II. Deformed nuclei2012In: Physical Review C. Nuclear Physics, ISSN 0556-2813, E-ISSN 1089-490X, Vol. 86, no 4, p. 044316-Article in journal (Refereed)
    Abstract [en]

    The binding energies of deformed even-even nuclei have been analyzed within the framework of a recently proposed microscopic-macroscopic model. We have used the semiclassical Wigner-Kirkwood (h) over bar expansion up to fourth order, instead of the usual Strutinsky averaging scheme, to compute the shell corrections in a deformed Woods-Saxon potential including the spin-orbit contribution. For a large set of 561 even-even nuclei with Z >= 8 and N >= 8, we find an rms deviation from the experiment of 610 keV in binding energies, comparable to the one found for the same set of nuclei using the finite range droplet model of Moller and Nix (656 keV). As applications of our model, we explore its predictive power near the proton and neutron drip lines as well as in the superheavy mass region. Next, we systematically explore the fourth-order Wigner-Kirkwood corrections to the smooth part of the energy. It is found that the ratio of the fourth-order to the second-order corrections behaves in a very regular manner as a function of the asymmetry parameter I = (N - Z)/A. This allows us to absorb the fourth-order corrections into the second-order contributions to the binding energy, which enables us to simplify and speed up the calculation of deformed nuclei.

  • 19. Bhagwat, A.
    et al.
    Vinas, X.
    Wyss, Ramon
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Schuck, P.
    WIGNER-KIRKWOOD METHOD FOR MICROSCOPIC-MACROSCOPIC CALCULATION OF BINDING ENERGIES2010In: International Journal of Modern Physics E, ISSN 0218-3013, Vol. 19, no 4, p. 747-758Article in journal (Refereed)
    Abstract [en]

    We propose to use the semi-classical Wigner-Kirkwood (h) over bar expansion to calculate shell corrections for spherical and deformed nuclei. The expansion is carried out up to fourth order in (h) over bar. A systematic study of Wigner-Kirkwood averaged energies is presented as a function of the deformation degrees of freedom. The shell corrections, along with the pairing energies obtained by using the Lipkin-Nogami scheme are used in the microscopic-macroscopic approach to calculate binding energies. The macroscopic part is obtained from a liquid drop formula with six adjustable parameters. Considering a set of 367 spherical nuclei, the liquid drop parameters are adjusted to reproduce the experimental binding energies, which yields a rms deviation of 630 keV.

  • 20. Bhagwat, A.
    et al.
    Viñas, X.
    Centelles, M.
    Schuck, P.
    Wyss, Ramon
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Recent developments in the Wigner - Kirkwood mass formula2013In: International Conference on Recent Trends in Nuclear Physics-2012 (ICRTNP-2012), 2013, p. 20-24Conference paper (Refereed)
    Abstract [en]

    The recently proposed microscopic - macroscopic model for nuclear masses, based on the shell corrections obtained by using the semi - classical Wigner - Kirkwood (WK) ℏ expansion of one body quantal partition function, has been extended to the even - even deformed nuclei. The nuclear potential is assumed to be deformed Woods - Saxon with spin - orbit contribution. The Coulomb potential is obtained by folding charge densities. The resulting partition function is expanded upto the fourth order in ℏ to obtain averaged energies. The shell corrections thus obtained along with pairing energies determined within the framework of the Lipkin - Nogami scheme constitute microscopic part of the model. The macroscopic part is obtained from a liquid drop formula, with nine adjustable parameters. These parameters are fitted by considering a large set of 561 even - even nuclei with Z ≥ 8 and N ≥ 8. The fit yields rms deviation of merely 610 keV from the corresponding experimental masses. A few applications of the mass formula are presented and discussed in this paper.

  • 21. Bhagwat, A.
    et al.
    Viñas, X.
    Centelles, M.
    Wyss, Ramon A.
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Schuck, P.
    Microscopic-Macroscopic Mass Calculations with Wigner-Kirkwood expansion2011In: International EFES-IN2P3 Conference on "Many Body Correlations from Dilute to Dense Nuclear Systems", MBC 2011, ISSN 1742-6588, Vol. 321, no 1, p. 012053-Article in journal (Refereed)
    Abstract [en]

    The systematic study and calculation of ground state nuclear masses continues to be one of the active and important areas of research in nuclear physics. The present work is an attempt to determine the ground state masses of nuclei spanning the entire periodic table, using the Microscopic-Macroscopic approach. The semi-classical Wigner-Kirkwood (WK) expansion method is used to calculate shell corrections for spherical and deformed nuclei. The expansion is achieved upto the fourth order in . The shell corrections, along with the pairing energies obtained by using the Lipkin-Nogami scheme, constitute the microscopic part of the nuclear masses. The macroscopic part is obtained from a liquid drop formula with six adjustable parameters. It is shown that the Microscopic-Macroscopic mass calculation thus achieved, yields reliable description of ground state masses of nuclei across the periodic table. The present status of the WK mass calculations and the possible future perspectives are discussed.

  • 22. Bhagwat, A.
    et al.
    Wyss, Ramon
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Satuła, W.
    Meng, J.
    Gambhir, Y. K.
    Investigation of band termination in the lower fp shell within the cranked relativistic mean field model2013In: International Conference on Recent Trends in Nuclear Physics-2012 (ICRTNP 2012), 2013, p. 105-108Conference paper (Refereed)
    Abstract [en]

    The excitation energy difference (ΔE) between the terminating states built on the f7/2 n and d3/2 -1f 7/2 n+1 configurations (here, 'n' denotes the number of valence particles outside the 40Ca core and the particle hole excitation across the magic gap 20 is of proton type) in the lower fp shell are studied systematically within the framework of the cranked relativistic mean field model. The ΔE thus defined, depends predominantly on the f 7/2 - d3/2 shell gap, and its evolution as a function of neutron - proton asymmetry. The latter, in turn, depends on the isoscalar - isovector balance in the spin - orbit potential. Therefore, a systematic investigation of the difference ΔE is expected to test quantitatively the predicted shell gaps as a function of isospin. We find that: 1) the conventional NL3 parameter set over estimates the ΔE values, implying that the said shell gap is over - estimated in this parametrization and 2) the largest deviation between the calculated and the experimental values of ΔE is obtained for the nucleus with the smallest asymmetry value in the set of nuclei considered, and that the deviation decreases with increasing asymmetry, indicating that the in RMF parametrization considered, the isoscalar - isovector balance in the spin - orbit potential requires improvement. We carry out a re - fit of the RMF parameters to attempt a remedy to these two problems. We find that in addition to the binding energies and charge radii, if a constraint is put on the f7/2 - d3/2 shell gap in the fit to the Lagrangian parameters, the overall agreement of ΔE with the experiment improves significantly, without disturbing the agreement already achieved for the bulk properties of the nuclei spanning the entire periodic table. At a finer level, however, it is found that the isoscalar - isovector balance in the spin orbit interaction is required to be improved further. A detailed work in this direction is in progress.

  • 23.
    Bhagwat, Ameeya
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Simple nuclear mass formula2014In: Physical Review C. Nuclear Physics, ISSN 0556-2813, E-ISSN 1089-490X, Vol. 90, no 6, p. 064306-Article in journal (Refereed)
    Abstract [en]

    A simple formula for ground state nuclear masses based on the microscopic-macroscopic approach is proposed. Considering a set of 2353 nuclei with Z >= 8 and N >= 8, the formula yields an rms deviation of just 266 keV. A few applications, including the loosely bound proton rich nuclei, superheavy nuclei, and cluster emitters, are presented and discussed, establishing the reliability of the proposed formula. The present investigation has a major advantage: it allows one to reliably parametrize the fluctuating part of the ground state energy. This result is very interesting and important, since the fluctuating part of the energy is related directly to the trace formula, which in turn encodes the interaction itself.

  • 24.
    Bhagwat, Ameeya
    et al.
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Gambhir, Y. K.
    Microscopic description of measured reaction cross sections at low projectile energies2006In: Physical Review C. Nuclear Physics, ISSN 0556-2813, E-ISSN 1089-490X, Vol. 73, no 2, p. 024604-Article in journal (Refereed)
    Abstract [en]

    Systematic and consistent microscopic description of measured reaction cross sections at low projectile en-ergies is presented. Finite-range Glauber model (GM-F) along with the Coulomb modification is used. The required inputs, namely the neutron and proton density distributions of the relevant projectiles and the targets, are calculated in the relativistic mean field framework. The GM-F reproduces the experiment well. At high projectile energies both the GM-F and the zero-range Glauber model in the optical limit (GM-Z) yield almost identical results; however, the GM-F in general is superior at low projectile energies, as expected.

  • 25.
    Bhagwat, Ameeya
    et al.
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Gambhir, Y. K.
    Microscopic description of recently measured reaction cross sections of neutron-rich nuclei in the vicinity of the N=20 and N=28 closed shells2008In: Physical Review C. Nuclear Physics, ISSN 0556-2813, E-ISSN 1089-490X, Vol. 77, no 2, p. 027602-Article in journal (Refereed)
    Abstract [en]

    The reaction cross sections for neutron-rich nuclei with 7 <= Z <= 18 on a Si-28 target at intermediate energies (30-65A MeV) are calculated and are compared with the corresponding recently reported new measurements. A finite-range Glauber model along with a Coulomb modification is used. The required nucleon density distributions of the relevant projectiles and the targets are obtained in the relativistic mean field framework. The calculations reproduce the experiment well. A simple phenomenological modification of the zero-range Glauber model is proposed to incorporate the finite-range effects. This one-parameter expression is found to reproduce the experimental reaction cross sections quite well.

  • 26.
    Bhagwat, Ameeya
    et al.
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Gambhir, Y. K.
    Recently measured reaction cross sections with low energy fp-shell nuclei as projectiles: Microscopic description2006In: Physical Review C. Nuclear Physics, ISSN 0556-2813, E-ISSN 1089-490X, Vol. 73, no 5, p. 054601-Article in journal (Refereed)
    Abstract [en]

    The finite range Glauber model along with the Coulomb modification is used to analyze recently measured reaction cross sections with neutron-deficient Ga, Ge, As, Se, and Br isotopes as low-energy projectiles incident on Si-28 target. The required input, namely the neutron and proton density distributions of the relevant projectiles and the target, are calculated in the relativistic mean-field framework. Though the calculations qualitatively agree with the experiment, on the average, slightly overestimate the cross sections. A phenomenological expression with a single parameter is proposed that consistently improves the agreement with the experiment.

  • 27.
    Bhagwat, Ameeya
    et al.
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Gambhir, Y. K.
    Systematics of strong absorption radii and its relevance to the calculation of reaction cross sections2009In: Journal of Physics G: Nuclear and Particle Physics, ISSN 0954-3899, E-ISSN 1361-6471, Vol. 36, no 2, p. 025105-Article in journal (Refereed)
    Abstract [en]

    Based on the detailed analysis of the reaction cross sections obtained using the finite range Glauber model, a systematic study of strong absorption radii is carried out. A simple phenomenological expression is proposed to calculate reaction cross sections directly using the average nucleon-nucleon cross section for a given target-projectile combination at given energy. Reliability of the model expression is demonstrated through a variety of illustrative examples.

  • 28.
    Bhagwat, Ameeya
    et al.
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Gambhir, Y. K.
    The alpha-nucleus potential for fusion and decay2008In: Journal of Physics G: Nuclear and Particle Physics, ISSN 0954-3899, E-ISSN 1361-6471, Vol. 35, no 6, p. 065109-Article in journal (Refereed)
    Abstract [en]

    The alpha-nucleus fusion cross sections at energies around and below the barrier and the alpha-decay half lives are calculated in the semi-classical WKB approach using the same microscopic as well as empirical alpha-nucleus potentials. The microscopic potential is generated within the double-folding framework using M3Y nucleon-nucleon interaction along with the required neutron and proton density distributions calculated in the relativistic mean field theory. It is found that in spite of the excellent results for the half lives the fusion cross sections are underestimated by almost a factor of 3. However, the experimental fusion cross sections can be reproduced by introducing a norm factor (overall multiplicative factor to the potential) 1.3 but this then worsens the agreement for half lives. To verify this observation and for comparison the calculations are repeated using some of the representative empirical potentials available in the literature. The same conclusion emerged. The present study thus indicates that the same alpha-nucleus potential may yield accurate description for both the alpha-nucleus fusion cross sections and alpha-decay half lives only with the introduction of additional parameter(s).

  • 29.
    Bhagwat, Ameeya
    et al.
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics. UM-DAE Centre for Excellence in Basic Sciences, India.
    Liotta, Roberto
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Cluster decay in the superallowed alpha decay region2017In: Physical Review C: Covering Nuclear Physics, ISSN 2469-9985, E-ISSN 2469-9993, Vol. 96, no 3, article id 031302Article in journal (Refereed)
    Abstract [en]

    The emissions of a particles and protons are the dominant decay channels in the neutron-deficient nuclei corresponding to the sdg major shell. The possibility of cluster emission is explored here. It is shown that the cluster decay mode has a small yet sizable branching ratio.

  • 30.
    Bhagwat, Ameeya
    et al.
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics. UM-DAE Centre for Excellence in Basic Sciences, Mumbai, India.
    Liotta, Roberto
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Consistent description of the cluster-decay phenomenon in transactinide nuclei2015In: Physical Review C. Nuclear Physics, ISSN 0556-2813, E-ISSN 1089-490X, Vol. 92, no 4Article in journal (Refereed)
    Abstract [en]

    Systematic investigation of the known even-even transactinide cluster emitters has been carried out by considering the cluster as a point particle and using the exact quantum mechanical treatment of the decay process. It is shown that the cluster decay phenomenon can be described reasonably well using a simple Woods-Saxon mean field. Sensitivity of the half-lives on various aspects of the mean field has been investigated in detail.

  • 31.
    Bhagwat, Ameeya
    et al.
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Vinas, X.
    Centelles, M.
    Schuck, P.
    Wyss, Ramon
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Microscopic-macroscopic approach for binding energies with the Wigner-Kirkwood method2010In: Physical Review C. Nuclear Physics, ISSN 0556-2813, E-ISSN 1089-490X, Vol. 81, no 4, p. 044321-Article in journal (Refereed)
    Abstract [en]

    The semiclassical Wigner-Kirkwood h expansion method is used to calculate shell corrections for spherical and deformed nuclei. The expansion is carried out up to fourth order in h. A systematic study of Wigner-Kirkwood averaged energies is presented as a function of the deformation degrees of freedom. The shell corrections, along with the pairing energies obtained by using the Lipkin-Nogami scheme, are used in the microscopic-macroscopic approach to calculate binding energies. The macroscopic part is obtained from a liquid drop formula with six adjustable parameters. Considering a set of 367 spherical nuclei, the liquid drop parameters are adjusted to reproduce the experimental binding energies, which yields a root mean square (rms) deviation of 630 keV. It is shown that the proposed approach is indeed promising for the prediction of nuclear masses.

  • 32. Bianco, L.
    et al.
    Page, R. D.
    Darby, I. G.
    Joss, D. T.
    Simpson, J.
    Al-Khalili, J. J.
    Cannon, A. J.
    Cederwall, Bo
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Eeckhaudt, S.
    Erturk, S.
    Gall, B.
    Hornillos, M. B. Gomez
    Grahn, T.
    Greenlees, P. T.
    Hadinia, Baharak
    KTH, School of Engineering Sciences (SCI), Physics.
    Heyde, K.
    Jakobsson, U.
    Jones, P. M.
    Julin, R.
    Juutinen, S.
    Ketelhut, S.
    Labiche, M.
    Leino, M.
    Leppanen, A. -P
    Nyman, M.
    O'Donnell, D.
    Paul, E. S.
    Petri, M.
    Peura, P.
    Puurunen, A.
    Rahkila, P.
    Ruotsalainen, P.
    Sandzelius, Mikael
    KTH, School of Engineering Sciences (SCI), Physics.
    Sapple, P. J.
    Saren, J.
    Scholey, C.
    Smirnova, N. A.
    Steer, A. N.
    Stevenson, P. D.
    Suckling, E. B.
    Thomson, J.
    Uusitalo, J.
    Venhart, M.
    Discovery of W-157 and Os-1612010In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 690, no 1, p. 15-18Article in journal (Refereed)
    Abstract [en]

    The nuclides W-157 and Os-161 have been discovered ill reactions of Ni-58 ion beams with a Cd-106 target. The Os-161 alpha-decay energy and half-life were 6890 +/- 12 keV and 640 +/- 60 mu s. The daughter W-157 nuclei beta-decayed with a half-life of 275 +/- 40 ms, populating both low-lying alpha-decaying states in Ta-157, which is consistent with a 7/2(-) ground state in W-157. Fine structure observed in the alpha decay of Os-161 places the lowest excited state in W-157 with 1(pi) = 9/2(-) at 318 +/- 30 key. The branching ratio of 5.5(-2.2)(+3.1)% indicates that Os-161 also has a 7/2(-) ground state. Shell-model calculations analysing the effects of monopole shifts and a tensor force on the relative energies of 2f(7/2) and 1h(9/2) neutron states in N = 83 isotones are presented. (C) 2010 Elsevier B.V. All rights reserved.

  • 33. Bianco, L.
    et al.
    Page, R. D.
    Joss, D. T.
    Simpson, J.
    Cederwall, Bo
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Hornillos, M. B. G.
    Greenlees, P. T.
    Hadinia, B.
    Jakobsson, U.
    Jones, P. M.
    et al,
    alpha-Decay branching ratios measured by gamma-ray tagging2008In: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 597, no 2-3, p. 189-191Article, review/survey (Refereed)
    Abstract [en]

    The nuclides Pt168-170 were produced by bombarding isotopically enriched Mo-92,Mo-94 targets with 336, 348 MeV Kr-78 ions. Prompt gamma rays were detected at the target position and provided a selection criterion for the Pt168-170 nuclei. This technique enables the problem of the background from higher-energy alpha decays in the spectrum to be circumvented. The Pt nuclei were separated in flight using the gas-filled separator RITU and implanted into the GREAT spectrometer, which was used to study subsequent alpha decays. The alpha-decay branching ratios of Os164-166 were deduced from the fraction of selected Pt168-170 nuclei correlated with a decays Of Os164-166. The resulting branching ratios agree with the literature values but can have improved precision.

  • 34. Biémont, É.
    et al.
    Ellmann, A.
    Lundin, P.
    Mannervik, S.
    Norlin, Lars-Olov
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Palmeri, P.
    Quinet, P.
    Rostohar, D.
    Royen, P.
    Schef, P.
    Decay of metastable states in NdII2007In: European Physical Journal D: Atomic, Molecular and Optical Physics, ISSN 1434-6060, E-ISSN 1434-6079, Vol. 41, no 2, p. 211-219Article in journal (Refereed)
    Abstract [en]

    The difficulty associated with an accurate determination of transition rates for forbidden lines in lowly ionized heavy elements is illustrated in the case of Nd II. We have investigated the radiative decay of the low-lying metastable levels in Nd+ including the two levels 4f(4)(I-5) 5d K-6(11/2) and 4f(4)(I-5) 5d I-6(13/2). In these two particular cases, using di. erent theoretical approaches, we. nd that the decay is dominated by the M1 channels but that the E2 contributions are of the same order of magnitude. These levels have also been studied experimentally by lifetime measurements with the heavy ion storage ring CRYRING of Stockholm University. The difficulties encountered when performing such experiments are underlined and discussed.

  • 35. Boso, A.
    et al.
    Lenzi, S. M.
    Recchia, F.
    Bonnard, J.
    Aydin, S.
    Bentley, M. A.
    Cederwall, Bo
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Clement, E.
    De France, G.
    Di Nitto, A.
    Dijon, A.
    Doncel, Maria
    KTH, School of Engineering Sciences (SCI), Physics.
    Ghazi Moradi, Farnaz
    KTH, School of Engineering Sciences (SCI), Physics.
    Gottardo, A.
    Henry, T.
    Huyuk, T.
    Jaworski, G.
    John, P. R.
    Juhasz, K.
    Kuti, I.
    Melon, B.
    Mengoni, D.
    Michelagnoli, C.
    Modamio, V.
    Napoli, D. R.
    Nyako, B. M.
    Nyberg, J.
    Palacz, M.
    Valiente-Dobon, J. J.
    ISOSPIN SYMMETRY BREAKING IN MIRROR NUCLEI Mg-23-Na-232017In: Acta Physica Polonica B, ISSN 0587-4254, E-ISSN 1509-5770, Vol. 48, no 3, p. 313-318Article in journal (Refereed)
    Abstract [en]

    Mirror energy differences (MED) are a direct consequence of isospin symmetry breaking. Moreover, the study of MED has proved to give valuable information of several nuclear structure properties. We present the results of an experiment performed in GANIL to study the MED in mirror nuclei Mg-23-Na-23 up to high spin. The experimental values are compared with state-of-the-art shell model calculations. This permits to enlighten several nuclear structure properties, such as the way in which the nucleons alignment proceeds, the radius variation with J, the role of the spin-orbit interaction and the importance of isospin symmetry breaking terms of nuclear origin.

  • 36. Brehwens, Karl
    et al.
    Bajinskis, Ainars
    Staaf, Elina
    Haghdoost, Siamak
    Cederwall, Bo
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Wojcik, Andrzej
    A new device to expose cells to changing dose rates of ionising radiation2011In: Radiation Protection Dosimetry, ISSN 0144-8420, E-ISSN 1742-3406, Vol. 148, no 3, p. 366-371Article in journal (Refereed)
    Abstract [en]

    In many exposure scenarios to ionising radiation, the dose rate is not constant. Despite this, most in vitro studies aimed at investigating the effects of ionising radiation are carried out exposing samples at constant dose rates. Consequently, very little data exist on the biological effects of exposures to changing dose rates. This may be due to technical limitations of standard irradiation facilities, but also to the fact that the importance of research in this area has not been appreciated. We have recently shown that cells exposed to a decreasing dose rate suffer higher levels of cytogenetic damage than do cells exposed to an increasing or a constant dose rate. To further study the effects of changing dose rates, a new device was constructed that permits the exposure of cell samples in tubes, flasks or Petri dishes to changing dose rates of X-rays. This report presents the technical data, performance and dosimetry of this novel device.

  • 37.
    Bäck, Torbjörn
    et al.
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Qi, Chong
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Cederwall, Bo
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Liotta, Roberto
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Ghazi Moradi, Farnaz
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Johnson, Arne
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Wyss, Ramon
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Wadsworth, R.
    Transition probabilities near Sn-100 and the stability of the N, Z=50 shell closure2013In: Physical Review C. Nuclear Physics, ISSN 0556-2813, E-ISSN 1089-490X, Vol. 87, no 3, p. 031306-Article in journal (Refereed)
    Abstract [en]

    Recent B(E2; 0(g.s.)(+) -> 2(1)(+)) measurements in light tin isotopes have revealed surprisingly large values relative to standard shell model predictions, generating an unexpected asymmetry in the B(E2) values with respect to the neutron midshell. This effect has triggered various speculations as to its origin, such as a possible weakening of the N, Z = 50 shell closure. Here we present new shell model calculations to investigate the origin of the observed asymmetric character of the B(E2) values in the tin isotopes. By including the effects of the neutron g(9/2) orbital below the N = 50 shell gap it is shown that Pauli blocking effects may play an important role near the N = 50 shell closure. A new set of single-particle energies and monopole interactions, fitted to the experimental data in the region, together with the isospin-dependent effective charge suggested by Bohr and Mottelson is shown to reproduce the experimental transition rate values in the Sn isotopic chain.

  • 38.
    Bäck, Torbjörn
    et al.
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Qi, Chong
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Cederwall, Bo
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Liotta, Roberto
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Moradi, Farnaz Ghazi
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Johnson, Arne
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Wyss, Ramon
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Wadsworth, R.
    The B(E2;0(gs)(+) -> 2(+)) systematics of Sn and Te isotopes in light of data in the light Sn region including a recent measurement in Te-108 using the combined recoil-decay-tagging-recoil-distance Doppler technique2012In: Physica Scripta, ISSN 0031-8949, E-ISSN 1402-4896, Vol. T150, p. 014003-Article in journal (Refereed)
    Abstract [en]

    An experimental technique combining the well-established alpha/p-decay-recoil-tagging method with a differential plunger has recently been successful in producing results in the neutron-deficient region near Sn-100. This experimental technique is briefly presented here and the result of a recent measurement for Te-108 is put in the context of the systematics of B(E-2) values for the Te and Sn isotopic chains. New state-of-the-art shell-model calculations are presented for the Sn data, and possible explanations for the unusually large B(E-2) values for the Sn isotopes near the N = 50 shell closure are given.

  • 39.
    Bäck, Torbjörn
    et al.
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Qi, Chong
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Ghazi Moradi, Farnaz
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Cederwall, Bo
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Johnson, Arne
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Liotta, Roberto
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Wyss, Ramon
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Al-Azri, H.
    Bloor, D.
    Brock, T.
    Wadsworth, R.
    Grahn, T.
    Greenlees, P. T.
    Hauschild, K.
    Herzan, A.
    Jacobsson, U.
    Jones, P. M.
    Julin, R.
    Juutinen, S.
    Ketelhut, S.
    Leino, M.
    Lopez-Martens, A.
    Nieminen, P.
    Peura, P.
    Rahkila, P.
    Rinta-Antila, S.
    Ruotsalainen, P.
    Sandzelius, M.
    Saren, J.
    Scholey, C.
    Sorri, J.
    Uusitalo, J.
    Go, S.
    Ideguchi, E.
    Cullen, D. M.
    Procter, M. G.
    Braunroth, T.
    Dewald, A.
    Fransen, C.
    Hackstein, M.
    Litzinger, J.
    Rother, W.
    Lifetime measurement of the first excited 2(+) state in (108)Te2011In: Physical Review C. Nuclear Physics, ISSN 0556-2813, E-ISSN 1089-490X, Vol. 84, no 4, p. 041306-Article in journal (Refereed)
    Abstract [en]

    The lifetime of the first excited 2(+) state in the neutron deficient nuclide (108)Te has been measured for the first time, using a combined recoil decay tagging and recoil distance Doppler shift technique. The deduced reduced transition probability is B(E2;0(g.s.)(+) -> 2(+)) = 0.39(-0.04)(+0.05)e(2)b(2). Compared to previous experimental data on neutron deficient tellurium isotopes, the new data point constitutes a large step (six neutrons) toward the N = 50 shell closure. In contrast to what has earlier been reported for the light tin isotopes, our result for tellurium does not show any enhanced transition probability with respect to the theoretical predictions and the tellurium systematics including the new data is successfully reproduced by state-of-the-art shell model calculations.

  • 40. Caballero, L.
    et al.
    Kleinheinz, P.
    Rubio, B.
    Algora, A.
    Blomqvist, Jan-Erik
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Dewald, A.
    Fitzler, A.
    Gadea, A.
    Jolie, J.
    Julin, R.
    Linnemann, A.
    Lunardi, S.
    Menegazzo, R.
    Möller, O.
    Nácher, E.
    Piiparinen, M.
    Yates, S. W.
    Two-phonon octupole excitation in 146Gd2006In: AIP Conf. Proc., 2006, p. 213-216Conference paper (Refereed)
    Abstract [en]

    The excited states in 146Gd have been re-investigated with the 144Sm(α,2n) reaction using a modern Ge γ-ray array including a polarimeter. Amongst the non-yrast states populated in this reaction we have identified the aligned 6 + member of the two-phonon octupole quartet from the observation of the E3 branching to the one phonon 3 - state. Our results represent the first observation of a 6 +→ 3 -→0 + E3 cascade in an even-even nucleus.

  • 41. Caceres, L.
    et al.
    Gorska, M.
    Jungclaus, A.
    Pfutzner, M.
    Grawe, H.
    Nowacki, F.
    Sieja, K.
    Pietri, S.
    Rudolph, D.
    Podolyak, Zs.
    Regan, P. H.
    Werner-Malento, E.
    Detistov, P.
    Lalkovski, S.
    Modamio, V.
    Walker, J.
    Andgren, Karin
    KTH, School of Engineering Sciences (SCI), Physics.
    Bednarczyk, P.
    Benlliure, J.
    Benzoni, G.
    Bruce, A. M.
    Casarejos, E.
    Cederwall, Bo
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Crespi, F. C. L.
    Doornenbal, P.
    Geissel, H.
    Gerl, J.
    Grebosz, J.
    Hadinia, Bahrak
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Hellstrom, M.
    Hoischen, R.
    Ilie, G.
    Khaplanov, Anton
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Kmiecik, M.
    Kojouharov, I.
    Kumar, R.
    Kurz, N.
    Maj, A.
    Mandal, S.
    Montes, F.
    Martinez-Pinedo, G.
    Myalski, S.
    Prokopowicz, W.
    Schaffner, H.
    Simpson, G. S.
    Steer, S. J.
    Tashenov, S.
    Wieland, O.
    Wollersheim, H. J.
    Spherical proton-neutron structure of isomeric states in Cd-1282009In: Physical Review C. Nuclear Physics, ISSN 0556-2813, E-ISSN 1089-490X, Vol. 79, no 1, p. 011301-Article in journal (Refereed)
    Abstract [en]

    The gamma-ray decay of isomeric states in the even-even nucleus Cd-128 has been observed. The nucleus of interest was produced both by the fragmentation of Xe-136 and the fission of U-238 primary beams. The level scheme was unambiguously constructed based on.. coincidence relations in conjunction with detailed lifetime analysis employed for the first time on this nucleus. Large-scale shell-model calculations, without consideration of excitations across the N = 82 shell closure, were performed and provide a consistent description of the experimental level scheme. The structure of the isomeric states and their decays exhibit coexistence of proton, neutron, and strongly mixed configurations due to p. interaction in overlapping orbitals for both proton and neutron holes.

  • 42. Carroll, R. J.
    et al.
    Andgren, Karin
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Cederwal, Bo
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Doncel, Maria
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Hadinia, Baharak
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics. Department of Physics, University of Guelph, Guelph, ON, Canada.
    Jacobsson, Ulrika
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics. University of Jyväskylä, Department of Physics, Jyväskylä, Finland.
    Sandzelius, Mikael
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Taylor, M. J.
    Thornthwaite, A.
    et al.,
    Excited states in the proton-unbound nuclide Ta-1582016In: Physical Review C. Nuclear Physics, ISSN 0556-2813, E-ISSN 1089-490X, Vol. 93, no 3, article id 034307Article in journal (Refereed)
    Abstract [en]

    Excited states in the neutron-deficient odd-odd proton-unbound nuclide Ta-158 have been investigated in two separate experiments. In the first experiment, Ir-166 nuclei were produced in the reactions of 380 MeV Kr-78 ions with an isotopically enriched Mo-92 target. The alpha-decay chain of the 9(+) state in Ir-166 was analyzed. Fine structure in the a decay of the 9(+) state in Re-162 established a 66 keV difference in excitation energy between the lowest-lying 9(+) and 10(+) states in Ta-158. Higher-lying states in Ta-158 were populated in the reactions of 255 MeV Ni-58 ions with an isotopically enriched Pd-102 target. Gamma-ray decay paths that populate, depopulate, and bypass a 19(-) isomeric state have been identified. The general features of the deduced level scheme are discussed and the prospects for observing proton emission branches from excited states are considered.

  • 43. Carroll, R. J.
    et al.
    Page, R. D.
    Joss, D. T.
    Uusitalo, J.
    Darby, I. G.
    Andgren, Karin
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Cederwall, Bo
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Eeckhaudt, S.
    Grahn, T.
    Gray-Jones, C.
    Greenlees, P. T.
    Hadinia, Baharak
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Jones, P. M.
    Julin, R.
    Juutinen, S.
    Leino, M.
    Leppänen, A. -P
    Nyman, M.
    O'Donnell, D.
    Pakarinen, J.
    Rahkila, P.
    Sandzelius, M.
    Sarén, J.
    Scholey, C.
    Seweryniak, D.
    Simpson, J.
    Competing decay modes of a high-spin isomer in the proton-unbound nucleus 158Ta2015In: Acta Physica Polonica B, ISSN 0587-4254, E-ISSN 1509-5770, Vol. 46, no 3, p. 695-698Article in journal (Refereed)
    Abstract [en]

    An isomeric state at high spin and excitation energy was recently observed in the proton-unbound nucleus 158Ta. This state was observed to decay by both α and γ decay modes. The large spin change required to decay via γ-ray emission incurs a lifetime long enough for α decay to compete. The α decay has an energy of 8644(11) keV, which is among the highest observed in the region, a partial half-life of 440(70) μs and changes the spin by 11h. In this paper, additional evidence supporting the assignment of this α decay to the high-spin isomer in 158Ta will be presented.

  • 44.
    Cederwall, Bo
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Development of a multimodality sensor for spectral photon counting CT, standard CT and PET2011In: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 648, no Suppl 1, p. S72-S74Article in journal (Refereed)
    Abstract [en]

    A prototype sensor module for multimodality medical imaging applications requiring awide intensity range has been developed. It consists of a silicon photomultiplier (SiPM)-scintillator sensor connected to a 100 kHz bandwidth current amplifier integrated with afour stage energy discriminator and a charge sensitive preamplifier. The electronics design allows for simultaneous read out of current level and discriminatory information of single photon energy or, optionally, high-resolution energy information via the charge preamplifier. This single-channel device is a proof-of-principle system designed primarily for combined spectral photon counting computed tomography (CT)/standard CT or combined with positron emission tomography (PET).

  • 45.
    Cederwall, Bo
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    NCNP 2011: Nordic Conference on Nuclear Physics 2011 (Stockholm, Sweden, 13-17 June 2011)2012In: Physica Scripta, ISSN 0031-8949, E-ISSN 1402-4896, Vol. T150, p. 010101-Article in journal (Other academic)
  • 46.
    Cederwall, Bo
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    System and method for photon detection2007Patent (Other (popular science, discussion, etc.))
  • 47.
    Cederwall, Bo
    et al.
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Ghazi Moradi, Farnaz
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Bäck, Torbjörn
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Johnson, Arne
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Blomqvist, Jan-Erik
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Clément, E.
    Grand Accélérateur National d´lons Lourds, Cean Cedex, France.
    de France, G.
    Grand Accélérateur National d´lons Lourds, Cean Cedex, France.
    Wadsworth, R.
    Department of Physics, University of York, UK.
    Andgren, Karin
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Lagergren, Karin
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Dijon, A.
    Grand Accélérateur National d´lons Lourds, Cean Cedex, France.
    Jaworski, G.
    Heavy Ion Laboratory, Univeristy of Warsaw, Warsaw, Poland.
    Liotta, Roberto
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Qi, Chong
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Nyakó, B. M.
    Institute of Nuclear Research of the Hungarian Academy of Sciences, Debrecen, Hungary.
    Nyberg, J.
    Department of Physics and Astronomy, Uppsala University, Uppsala, Sweden.
    Palacz, M.
    Heavy Ion Laboratory, Univeristy of Warsaw, Warsaw, Poland.
    Al-Azri, H.
    Department of Physics, University of York, UK.
    Algora, A.
    IFIC, CSIC University of Valencia, Valencia, Spain.
    de Angelis, G.
    Instituto Nazionael di Fisica Nucleare, Laboratori Nazionali di Legnaro, Legnaro, Italy.
    Atac, Ayse
    KTH, School of Engineering Sciences (SCI).
    Bhattacharyya, S.
    Grand Accélérateur National d´lons Lourds, Cean Cedex, France.
    Brock, T.
    Department of Physics, University of York, York, UK.
    Brown, J. R.
    Department of Physics, University of York, York, UK.
    Davies, P.
    Department of Physics, University of York, York, UK.
    Di Nitto, A.
    Dipartimento di Scienze Fisiche, Universitá di Napoli and Instituto Nazionale di Fisica Nucleare, Napoli, Italy.
    Dombrádi, Zs.
    Institute of Nuclear Research of the Hungarian Academy of Science, Debrecen, Hungary.
    Gadea, A.
    IFIC, CSIC, University of Valencia, Valencia, Spain.
    Gál, J.
    Institute of Nuclear Research of the Hungarian Academy of Science, Debrecen, Hungary.
    Hadinia, Baharak
    KTH, School of Engineering Sciences (SCI), Physics.
    Johnston-Theasby, F.
    Department of Physics, University of York, York, UK.
    Joshi, P.
    Department of Physics, University of York, York, UK.
    Juhász, K.
    Department of Information Technology, Universty of Debrecen, Debrecen, Hungary.
    Julin, R.
    Department of Physics, University of Jyväskylä, Jyväskylä, Finland.
    Jungclaus, A.
    Instituto de Estructura de la Materia, Madrid, Spain .
    Kalinka, G.
    Institute of Nuclear Research of the Hungarian Academy of Sciences, Debrecen, Hungary.
    Kara, S. O.
    Department of Physics, Ankara University, Tandogan Ankarar, Turkey.
    Khaplanov, Anton
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Kownacki, J.
    Heavy Ion Laboratory, Universty of Warsaw, Warsaw, Poland.
    La Rana, G.
    Dipartimento di Scienze Fisiche, Universitá di Napoli and Instituto Nazionale di Fisica Nucleare, Napoli, Italy.
    Lenzi, S. M.
    Dipartimento di Fisica dell'Universitá di Padova and Instituto Nazionale di Fisica Nucleare, Sezione di Padova, Padova, Italy.
    Molnár, J.
    Institute of Nuclear Research of the Hungarian Academy of Sciences, Debrecen, Hungary.
    Moro, R.
    Dipartimento di Scienze Fisiche, Universitá di Napoli and Instituto Nazionale di Fisica Nucleare, Napoli, Italy.
    Napoli, D. R.
    Instituto Nazionale di Fisica Nucleare, Laboratori Natzionali di Legnaro, Legnaro, Italy.
    Nara Singh, B. S.
    Department of Physics, University of York, York, UK.
    Persson, Andreas
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Recchia, F.
    Dipartimento di Fisica dell'Universitá di Padova and Instituto Nazionale di Fisica Nucleare, Sezione di Padova, Padova, Italy.
    Sandzelius, Mikael
    KTH, School of Engineering Sciences (SCI), Physics.
    Scheurer, J. -N
    Université Bordeaux, Centre d'Etudes Nucléaires de Bordeaux Gradignan, Gradignan, France.
    Sletten, G.
    The Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark.
    Sohler, D.
    Institute of Nuclear Research of the Hungarian Academy of Sciences, Debrecen, Hungary.
    Söderström, P. -A
    Department of Physics and Astromony, Uppsala University, Uppsala, Sweden.
    Taylor, M. J.
    Department of Physics, University of York, York, UK.
    Timár, J.
    Institute of Nuclear Research of the Hungarian Academy of Sciences, Debrecen, Hungary.
    Valiente-Dobón, J. J.
    instituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Legnaro, Legnaro, Italy.
    Vardaci, E.
    Dipartimento di Scienze Fisiche, Universitá di Napoli and Instituto Nazionale di Fisica Nucleare, Napoli, Italy.
    Williams, S.
    TRIUMF, Vancouver, British Columbia, Canada.
    Evidence for a spin-aligned neutron-proton paired phase from the level structure of 92Pd2011In: Nature, ISSN 0028-0836, E-ISSN 1476-4687, Vol. 469, no 7328, p. 68-71Article in journal (Refereed)
    Abstract [en]

    Shell structure and magic numbers in atomic nuclei were generally explained by pioneering work(1) that introduced a strong spin-orbit interaction to the nuclear shell model potential. However, knowledge of nuclear forces and the mechanisms governing the structure of nuclei, in particular far from stability, is still incomplete. In nuclei with equal neutron and proton numbers (N = Z), enhanced correlations arise between neutrons and protons (two distinct types of fermions) that occupy orbitals with the same quantum numbers. Such correlations have been predicted to favour an unusual type of nuclear superfluidity, termed isoscalar neutron-proton pairing(2-6), in addition to normal isovector pairing. Despite many experimental efforts, these predictions have not been confirmed. Here we report the experimental observation of excited states in the N = Z = 46 nucleus Pd-92. Gamma rays emitted following the Ni-58(Ar-36,2n)Pd-92 fusion-evaporation reaction were identified using a combination of state-of-the-art high-resolution c-ray, charged-particle and neutron detector systems. Our results reveal evidence for a spin-aligned, isoscalar neutron-proton coupling scheme, different from the previous prediction(2-6). We suggest that this coupling scheme replaces normal superfluidity (characterized by seniority coupling(7,8)) in the ground and low-lying excited states of the heaviest N = Z nuclei. Such strong, isoscalar neutron-proton correlations would have a considerable impact on the nuclear level structure and possibly influence the dynamics of rapid proton capture in stellar nucleosynthesis.

  • 48.
    Cederwall, Bo
    et al.
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Sandzelius, Mikael
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Andgren, Karin
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Khaplanov, Anton
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Wyss, Ramon
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Evidence for enhanced collectivity in Te-I-Xe nuclei near the N=Z=50 double shell closure2007In: PROTON EMITTING NUCLEI AND RELATED TOPICS / [ed] Ferreira, LS; Arumugam, P, MELVILLE, USA: AMER INST PHYSICS , 2007, Vol. 961, p. 156-162Conference paper (Refereed)
    Abstract [en]

    Gamma-ray transitions have been identified for the first time in the extremely neutron-deficient T-z = 1 nuclide Xe-110 and the energies of the three lowest excited states in the ground-state band have been deduced. A level scheme has also been constructed for the proton-unbound, T-z = 3/2 nuclide I-109, exhibiting band structures built on g(7/2) and h(11/2) states in a weakly deformed, triaxial nucleus. In addition, a third band is proposed to be bui It oil a g(7/2) orbital coupled to an octupole-vibrational phonon of the Te-108 core. The results were obtained in a recoil-decay tagging experiment using the Ni-58(Fe-54,2n/p2n) reaction at a beam energy of 195 MeV. The experiment was performed using the highly efficient JUROGAM y-ray spectrometer in conjunction with the RITU gas-filled recoil separator and the GREAT focal -plane spectrometer. The results on Xe-110 establish a breaking of the normal trend of increasing first excited 2(+) and 4(+) level energies as a function of decreasing neutron number as the N = 50 major shell gap is approached for the neutron-deficient Xe isotopes. This unusual feature is suggested to be an effect of enhanced collectivity, possibly arising from isoscalar n-p interactions becoming increasingly important close to the N = Z line. Features in the low-lying levels of Te-106 and I-109, showing similar trends, are also discussed.

  • 49.
    Changizi, Sara A.
    et al.
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Qi, Chong
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Wyss, Ramon
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Empirical pairing gaps, shell effects, and di-neutron spatial correlation in neutron-rich nuclei2015In: Nuclear Physics A, ISSN 0375-9474, E-ISSN 1873-1554, Vol. 940, p. 210-226Article in journal (Refereed)
    Abstract [en]

    The empirical pairing gaps derived from four different odd-even mass staggering formulas are compared. By performing single-j shell and multi-shell seniority model calculations as well as by using the standard HFB approach with Skyrme force we show that the simplest three-point formula δC(3)(N)=12[B(N,Z)+B(N-2,Z)-2B(N-1,Z)] can provide a good measure of the neutron pairing gap in even-N nuclei. It removes to a large extent the contribution from the nuclear mean field as well as contributions from shell structure details. It is also less contaminated by the Wigner effect for nuclei around N=Z. We also show that the strength of δC(3)(N) can serve as a good indication of the two-particle spatial correlation in the nucleus of concern and that the weakening of δC(3)(N) in some neutron-rich nuclei indicates that the di-neutron correlation itself is weak in these nuclei.

  • 50.
    Changizi, Sara A.
    et al.
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Qi, Chong
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Physics.
    Odd-even staggering in neutron drip line nuclei2016In: Nuclear Physics A, ISSN 0375-9474, E-ISSN 1873-1554, Vol. 951, p. 97-115Article in journal (Refereed)
    Abstract [en]

    We have done systematic Hartree-Fock-Bogoliubov calculations in coordinate space on the one-quasi-particle energies and binding energy odd-even staggering (OES) in semi-magic nuclei with the zero-range volume, mixed and surface pairing forces in order to explore the influence of their density dependence. The odd-N isotopes are calculated within the blocking scheme. The strengths for the pairing forces are determined in two schemes by fitting locally to reproduce pairing gap in 120Sn and globally to all available data on the OES of semi-magic nuclei with Z≥8. In the former calculations, there is a noticeable difference between the neutron mean gaps in neutron-rich O, Ca, Ni and Sn isotopes calculated with the surface pairing and those with the mixed and volume pairing. The difference gets much smaller if the globally optimized pairing strengths are employed. The heavier Pb isotopes show the opposite trend. Moreover, large differences between the mean gap and the OES may be expected in both calculations when one goes towards the neutron drip line.

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