| 1. |
- Rudolph, Dirk, et al.
(författare)
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Rotational Bands in the Semi-magic Nucleus 57Ni
- 2010
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Ingår i: Journal of Physics G: Nuclear and Particle Physics. - : IOP Publishing. - 0954-3899 .- 1361-6471. ; 37:7
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Tidskriftsartikel (refereegranskat)abstract
- Two rotational bands have been identified and characterized in the proton-magic N = Z + 1 nucleus Ni-57. These bands complete the systematics of well-and superdeformed rotational bands in the light nickel isotopes starting from doubly magic Ni-56 to Ni-60. High-spin states in Ni-57 have been produced in the fusion-evaporation reaction Si-28(S-32, 2p1n)Ni-57 and studied with the gamma-ray detection array GAMMASPHERE operated in conjunction with detectors for evaporated light charged particles and neutrons. The features of the rotational bands in Ni-57 are compared to those of neighbouring isotopes and interpreted by means of configuration-dependent cranked Nilsson-Strutinsky calculations. The two observed high-spin bands are considered signature partners and assigned to configurations with one 1g(9/2) proton and one 1g(9/2) neutron, resulting in an unambiguous understanding of the energetically favoured signature alpha = -1/2 band but a somewhat less satisfactory description of the signature alpha = +1/2 band.
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| 2. |
- Abelev, B., et al.
(författare)
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Technical Design Report for the Upgrade of the ALICE Inner Tracking System
- 2014
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Ingår i: Journal of Physics G: Nuclear and Particle Physics. - : IOP Publishing. - 0954-3899 .- 1361-6471. ; 41:8
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Tidskriftsartikel (refereegranskat)abstract
- LICE (A Large Ion Collider Experiment) is studying the physics of strongly interacting matter, and in particular the properties of the Quark–Gluon Plasma (QGP), using proton–proton, proton–nucleus and nucleus–nucleus collisions at the CERN LHC (Large Hadron Collider). The ALICE Collaboration is preparing a major upgrade of the experimental apparatus, planned for installation in the second long LHC shutdown in the years 2018–2019. A key element of the ALICE upgrade is the construction of a new, ultra-light, high-resolution Inner Tracking System (ITS) based on monolithic CMOS pixel detectors. The primary focus of the ITS upgrade is on improving the performance for detection of heavy-flavour hadrons, and of thermal photons and low-mass di-electrons emitted by the QGP. With respect to the current detector, the new Inner Tracking System will significantly enhance the determination of the distance of closest approach to the primary vertex, the tracking efficiency at low transverse momenta, and the read-out rate capabilities. This will be obtained by seven concentric detector layers based on a 50 μm thick CMOS pixel sensor with a pixel pitch of about 30×30 μm2. This document, submitted to the LHCC (LHC experiments Committee) in September 2013, presents the design goals, a summary of the R&D activities, with focus on the technical implementation of the main detector components, and the projected detector and physics performance.
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| 3. |
- Abelev, B., et al.
(författare)
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Upgrade of the ALICE Experiment Letter Of Intent
- 2014
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Ingår i: Journal of Physics G: Nuclear and Particle Physics. - : IOP Publishing. - 0954-3899 .- 1361-6471. ; 41:8
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Tidskriftsartikel (refereegranskat)abstract
- ALICE (A Large Ion Collider Experiment) is studying the physics of strongly interacting matter, and in particular the properties of the Quark–Gluon Plasma (QGP), using proton–proton, proton–nucleus and nucleus–nucleus collisions at the CERN LHC (Large Hadron Collider). The ALICE Collaboration is preparing a major upgrade of the experimental apparatus, planned for installation in the second long LHC shutdown in the years 2018–2019. These plans are presented in the ALICE Upgrade Letter of Intent, submitted to the LHCC (LHC experiments Committee) in September 2012. In order to fully exploit the physics reach of the LHC in this field, high-precision measurements of the heavy-flavour production, quarkonia, direct real and virtual photons, and jets are necessary. This will be achieved by an increase of the LHC Pb–Pb instant luminosity up to 6×1027 cm−2s−1 and running the ALICE detector with the continuous readout at the 50 kHz event rate. The physics performance accessible with the upgraded detector, together with the main detector modifications, are presented.
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| 4. |
- Armesto, Nestor, et al.
(författare)
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Mass effect and coherence in medium-induced QCD radiation off a q(q)over-bar antenna
- 2011
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Ingår i: Journal of Physics G: Nuclear and Particle Physics. - : IOP Publishing. - 0954-3899 .- 1361-6471. ; 38:12
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Tidskriftsartikel (refereegranskat)abstract
- The medium-induced one-gluon radiation spectrum off a massive quark-antiquark (q (q) over bar) antenna traversing a colored QCD medium is calculated in this contribution. The gluon spectrum off the antenna computed at first order in the opacity expansion is collinear finite but infrared divergent, which is different from the result obtained from an independent emitter which is both infrared and collinear finite. The interference between emitters dominates the soft gluon radiation when the antenna opening angle is small and the emitted gluon is soft, whereas the antenna behaves like a superposition of independent emitters when the opening angle is large and the radiated gluon is hard. As a phenomenological consequence, we investigate the energy lost by the projectiles due to the radiation. In general, the size of the mass effects is similar in both cases.
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| 5. |
- Avsar, E., et al.
(författare)
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Eccentricity and elliptic flow in pp collisions at the LHC
- 2011
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Ingår i: Journal of Physics G: Nuclear and Particle Physics. - : IOP Publishing. - 0954-3899 .- 1361-6471. ; 38:12
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Tidskriftsartikel (refereegranskat)abstract
- High-multiplicity proton-proton collisions at the LHC may exhibit collective phenomena such as elliptic flow. We study this issue using DIPSY, a brand-new Monte Carlo event generator which features almost-NLO BFKL dynamics and describes the transverse shape of the proton including all fluctuations. We predict the eccentricity of the collision as a function of the multiplicity and estimate the magnitude of elliptic flow. We suggest that flow can be signaled by a sign change in the four-particle azimuthal correlation.
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| 6. |
- Borge, M. J. G., et al.
(författare)
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Rare beta p decays in light nuclei
- 2013
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Ingår i: Journal of Physics G: Nuclear and Particle Physics. - : IOP Publishing. - 0954-3899 .- 1361-6471. ; 40:3, s. art.no. 035109-
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Tidskriftsartikel (refereegranskat)abstract
- Beta-delayed proton emission may occur at very low rates in the decays of the light nuclei Be-11 and B-8. This paper explores the potential physical significance of such decays, estimates their rates and reports on first attempts to detect them: an experiment at ISOLDE/CERN gives a branching ratio for Be-11 of ( 2.5 +/- 2.5) x 10(-6) and an experiment at JYFL a 95% confidence upper limit of 2.6 x 10(-5) for B-8.
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| 7. |
- Ershov, S. N., et al.
(författare)
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Halo formation and breakup: lessons and open questions
- 2010
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Ingår i: Journal of Physics G: Nuclear and Particle Physics. - : IOP Publishing. - 0954-3899 .- 1361-6471. ; 37:6
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Tidskriftsartikel (refereegranskat)abstract
- A quarter of a century's concerted international work in halo physics has resulted in an extended nuclear paradigm encompassing the limits of existence of cold nuclei and also structures beyond-continuum structures of open (nuclear) quantum systems. Realistic working models, based on cluster constituents, have sprung out of the very nature of halo phenomena, in particular from the three-body Borromean property of two-neutron halos, the lack of low-lying binary breakup channels. This has provided transparency and possibility for insight into new quantum behaviour, also in continua beyond driplines-a focus of this status assessment. Breakup spectra and progressively exclusive correlation cross sections can be computed and show, where relevant data exist, not only that general agreement is encouraging but also that some exclusive observables exhibit significant disagreement that has to be clarified. Progress in studies of two-proton emitters has provided another pathway beyond driplines, where again few-body theory appears promising.
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| 8. |
- Forssen, Christian, 1974, et al.
(författare)
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Systematics of 2+ states in C isotopes from the no-core shell model
- 2013
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Ingår i: Journal of Physics G: Nuclear and Particle Physics. - : IOP Publishing. - 0954-3899 .- 1361-6471. ; 40:5, s. 055105-
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Tidskriftsartikel (refereegranskat)abstract
- We study low-lying states of even carbon isotopes in the range A = 10-20 within the large-scale no-core shell model. Using several accurate nucleon-nucleon (NN) as well as NN plus three-nucleon (NNN) interactions, we calculate excitation energies of the lowest 2(+) state, the electromagnetic B(E2; 2(1)(+) -> 0(1)(+)) transition rates, and the 2(1)(+) quadrupole moments as well as selected electromagnetic transitions among other states. Recent experimental campaigns to measure 2(+)-state lifetimes indicate an interesting evolution of nuclear structure that pose a challenge to reproduce theoretically from first principles. Our calculations do not include any effective charges or other fitting parameters. However, calculated results extrapolated to infinite model spaces are also presented. The model-dependence of those results is discussed. Overall, we find good agreement with the experimentally observed trends, although our extrapolated B(E2; 2(1)(+) -> 0(1)(+)) value for C-16 is lower compared to the most recent measurements. Relative transition strengths from higher excited states are investigated and the influence of NNN forces is discussed. In particular for 16C we find a remarkable sensitivity of the transition rates from higher excited states to the details of the nuclear interactions.
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| 9. |
- Hamamoto-Kuroda, Ikuko
(författare)
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Change of shell structure and magnetic moments of odd-N deformed nuclei towards the neutron drip line
- 2010
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Ingår i: Journal of Physics G: Nuclear and Particle Physics. - : IOP Publishing. - 0954-3899 .- 1361-6471. ; 37:5
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Tidskriftsartikel (refereegranskat)abstract
- Examples of the change of neutron shell structure in both weakly bound and resonant neutron one-particle levels in nuclei towards the neutron drip line are exhibited. It is shown that the shell-structure change due to the weak binding may lead to the deformation of those nuclei with the neutron numbers N approximate to 8, 20, 28 and 40, which are known to be magic numbers in stable nuclei. Nuclei in the 'island of inversion' are most easily and in a simple manner understood in terms of deformation. As an example of spectroscopic properties other than single-particle energies, magnetic moments of some weakly bound possibly deformed odd-N nuclei with neutron numbers close to those traditional magic numbers are given, which are calculated using the wavefunction of the last odd particle in deformed Woods-Saxon potentials.
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| 10. |
- Hoischen, Robert, et al.
(författare)
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Isomeric Mirror States as Probes for Effective Charges in the Lower pf Shell
- 2011
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Ingår i: Journal of Physics G: Nuclear and Particle Physics. - : IOP Publishing. - 0954-3899 .- 1361-6471. ; 38:3
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Tidskriftsartikel (refereegranskat)abstract
- Following the fragmentation of a 550 MeV u(-1)primary beam of Ni-58, time-and energy-correlated gamma decays from isomeric states in neutron-deficient nuclei in the 1f(7/2) shell have been identified using the GSI fragment separator in combination with the RISING Ge-detector array. The results on isomers in the mirror pairs Ti-43(22)21-Sc-43(21)22 (I-pi = 3/2(+) and 19/2(-)), Cr-45(24)21-Sc-45(21)24 (I-pi = 3/2(+)) and V-45(23)22-Ti-45(22)23 (I-pi = 3/2(-)) are discussed in the framework of large scale pf and sdpf shell-model calculations, the former in conjunction with isospin symmetry breaking effects with emphasis on effective charges.
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