Szilner, S. et al, & Gadea, A. (2011). Interplay between single-particle and collective excitations in argon isotopes populated by transfer reactions. Phys. Rev. C, 84(1), 014325–7pp.
Abstract: New gamma transitions have been identified in argon isotopes in (40)Ar + (208)Pb multiple transfer reactions by exploiting, in a fragment-gamma measurement, the new generation of magnetic spectrometers based on trajectory reconstruction coupled to large gamma arrays. The coupling of single-particle degrees of freedom to nuclear vibration quanta was discussed. The interpretation of the newly observed states within a particle-phonon coupling picture was used to consistently follow, via their excitation energies, the evolution of collectivity in odd Ar isotopes. The proposed level schemes are supported by the results of sd-pf shell-model calculations, which have been also employed to evaluate the strength functions of the populated states.
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Morales, A. I. et al, Agramunt, J., Algora, A., Gadea, A., Molina, F., & Rubio, B. (2011). Synthesis of N=127 isotones through (p,n) charge-exchange reactions induced by relativistic (208)Pb projectiles. Phys. Rev. C, 84(1), 011601–5pp.
Abstract: The production cross sections of four N = 127 isotones ((207)Hg, (206)Au, (205)Pt, and (204)Ir) have been measured using (p,n) charge-exchange reactions, induced in collisions of a (208)Pb primary beam at 1 A GeV with a Be target. These data allow one to investigate the use of a reaction mechanism to extend the limits of the chart of nuclides toward the important r-process nuclei in the region of the third peak of elemental abundance distribution.
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Dillmann, I., Coquard, L., Domingo-Pardo, C., Kappeler, F., Marganiec, J., Uberseder, E., et al. (2011). Cross sections for proton-induced reactions on Pd isotopes at energies relevant for the gamma process. Phys. Rev. C, 84(1), 015802–11pp.
Abstract: Proton-activation reactions on natural and enriched palladium samples were investigated via the activation technique in the energy range of E(p) = 2.75-9 MeV, close to the upper end of the respective Gamow window of the. process. We have determined cross sections for (102)Pd(p,gamma)(103)Ag, (104)Pd(p,gamma)(105)Ag, and (105)Pd(p,n)(105)Ag, as well as partial cross sections of (104)Pd(p,n)(104)Ag(g), (105)Pd(p,gamma)(106)Ag(m), (106)Pd(p,n)(106)Ag(m), and (110)Pd(p,n)(110)Ag(m) with uncertainties between 3% and 15% for constraining theoretical Hauser-Feshbach rates and for direct use in gamma-process calculations.
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Molina, R., Xiao, C. W., & Oset, E. (2012). J/psi reaction mechanisms and suppression in the nuclear medium. Phys. Rev. C, 86(1), 014604–9pp.
Abstract: Recent studies of the interaction of vector mesons with nuclei make possible and opportune the study of the interaction of the J/psi with nuclei and the investigation of the origin of the J/psi suppression in its propagation thorough a nuclear medium. We observe that the transition of J/psi N to VN with V being a light vector, rho, omega, phi, together with the inelastic channels, J/psi N -> (D) over bar Lambda(c) and J/psi N -> (D) over bar Sigma(c), leads to a particular shape of the inelastic cross section. Analogously, we consider the mechanisms where the exchanged D collides with a nucleon and gives pi Lambda(c) or pi Sigma(c). The cross section has a peak around root s = 4415 MeV, where the J/psi N couples to a resonance predicted recently. We study the transparency ratio for electron-induced J/psi production in nuclei at about 10 GeV and find that 30-35% of the J/psi produced in heavy nuclei are absorbed inside the nucleus. This ratio is in line with depletions of J/psi through matter observed in other reactions.
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ATLAS Collaboration(Aad, G. et al), Amoros, G., Cabrera Urban, S., Castillo Gimenez, V., Costa, M. J., Ferrer, A., et al. (2012). Measurement of the azimuthal anisotropy for charged particle production in root s(NN)=2.76 TeV lead-lead collisions with the ATLAS detector. Phys. Rev. C, 86(1), 014907–41pp.
Abstract: Differential measurements of charged particle azimuthal anisotropy are presented for lead-lead collisions at root sNN = 2.76 TeV with the ATLAS detector at the LHC, based on an integrated luminosity of approximately 8 μb(-1). This anisotropy is characterized via a Fourier expansion of the distribution of charged particles in azimuthal angle relative to the reaction plane, with the coefficients v(n) denoting the magnitude of the anisotropy. Significant v(2)-v(6) values are obtained as a function of transverse momentum (0.5 < p(T) < 20 GeV), pseudorapidity (|eta| < 2.5), and centrality using an event plane method. The v(n) values for n >= 3 are found to vary weakly with both eta and centrality, and their p(T) dependencies are found to follow an approximate scaling relation, v(n)(1/n)(p(T)) proportional to v(2)(1/2)(p(T)), except in the top 5% most central collisions. A Fourier analysis of the charged particle pair distribution in relative azimuthal angle (Delta phi = phi(a)-phi(b)) is performed to extract the coefficients v(n,n) = < cos n Delta phi >. For pairs of charged particles with a large pseudorapidity gap (|Delta eta = eta(a) – eta(b)| > 2) and one particle with p(T) < 3 GeV, the v(2,2)-v(6,6) values are found to factorize as v(n,n)(p(T)(a), p(T)(b)) approximate to v(n) (p(T)(a))v(n)(p(T)(b)) in central and midcentral events. Such factorization suggests that these values of v(2,2)-v(6,6) are primarily attributable to the response of the created matter to the fluctuations in the geometry of the initial state. A detailed study shows that the v(1,1)(p(T)(a), p(T)(b)) data are consistent with the combined contributions from a rapidity-even v(1) and global momentum conservation. A two-component fit is used to extract the v(1) contribution. The extracted v(1) isobserved to cross zero at pT approximate to 1.0 GeV, reaches a maximum at 4-5 GeV with a value comparable to that for v(3), and decreases at higher p(T).
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