| 1. |
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| 2. |
- Markenroth, Karin, 1973, et al.
(author)
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Crossing the dripline to N-11 using elastic resonance scattering
- 2000
-
In: Physical Review C - Nuclear Physics. - 2469-9985 .- 2469-9993. ; 6203:3
-
Journal article (peer-reviewed)abstract
- The level structure of the unbound nucleus N-11 has been studied by C-10+p elastic resonance scattering in inverse geometry with the LISE3 spectrometer at GANIL, using a C-10 beam with an energy of 9.0 MeV/ nucleon. An additional measurement was done at the A1200 spectrometer at MSU. The excitation function above the C-10+p threshold has been determined up to 5 MeV. A potential-model analysis revealed three resonance states at energies 1.27(-0.05)(+0.18) MeV (Gamma = 1.44 +/- 0.2 MeV), 2.01(-0.05)(+0.15) MeV (Gamma = 0.84 +/- 0.2 MeV), and 3.75 +/- 0.05 MeV (Gamma = 0.60 +/- 0.05 MeV) with the spin-parity assignments I-pi=1/2+,1/2,-,5/2+, respectively. Hence, N-11 is shown to have a ground state parity inversion completely analogous to its mirror partner Be-11. A narrow resonance in the excitation function at 4.33 +/- 0.05 MeV was also observed and assigned spin parity 3/2-.
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| 3. |
- Shergur, J., et al.
(author)
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beta-decay studies of Sn135-137 using selective resonance laser ionization techniques
- 2002
-
In: Physical Review C - Nuclear Physics. - 2469-9985 .- 2469-9993. ; 65:3
-
Journal article (peer-reviewed)abstract
- The decays of the very neutron rich Sn isotopes Sn135-137 were studied at CERN/ISOLDE using isotopic and isobaric selectivity achieved by the use of a resonance ionization laser ion source and mass spectroscopy, respectively. Neutron decay rates, gamma-ray singles, and gamma-gamma coincidence data were collected as a function of time. The half-life (T-1/2) and delayed neutron emission probability (P-n) values of 135 Sn were measured to be 530(20) ms and 21(3)%, respectively. For Sn-136, a T-1/2 of 250(30) ms was determined along with a P-n value of 30(5)%. For Sn-137, a T-1/2 of 190(60) ms and a P-n value of 58(15)% were deduced. Identification of low-energy transitions in Sb-135 was made possible by comparison of laser-on and laser-off gamma-ray spectra. Those data combined with gamma-gamma coincidence spectra were used to construct a level scheme for Sb-135 that includes an unexpectedly low first excited state at 282 keV. A ground state beta branch of 33.2% was measured by following the growth and decay of the Sb-135 daughter. Shell-model calculations are consistent with the observed Sb-135 level structure and can account for a lowered first excited state.
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| 4. |
- Weissman, L., et al.
(author)
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beta decay of Ar-49,Ar-50
- 2003
-
In: Physical Review C - Nuclear Physics. - 2469-9985 .- 2469-9993. ; 67:5
-
Journal article (peer-reviewed)abstract
- Information on gross beta-decay properties of neutron-rich noble gas isotopes Ar-49,Ar-50 was obtained at the PSB-ISOLDE facility at CERN using isobaric selectivity achieved by the combination of a plasma ion source with a cooled transfer line and subsequent mass separation. A doubly charged beam was used in the case of Ar-49 to suppress the corresponding multicharged background from heavier noble gas fission products. The comparison of the obtained data with results of quasiparticle random-phase approximation calculations indicates that the N=28 shell is not disturbed significantly for neutron-rich Ar nuclei. The obtained results are useful for better understanding of the origin of the Ca-48/Ca-46 isotopic anomaly discovered in inclusions from the Allende meteorite.
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| 5. |
- Weissman, L., et al.
(author)
-
beta(+) decay of Ga-61
- 2002
-
In: Physical Review C - Nuclear Physics. - 2469-9985 .- 2469-9993. ; 65:4, s. 054314-
-
Journal article (peer-reviewed)abstract
- The mirror beta(+) decay of Ga-61 was investigated by means of beta- and gamma-ray spectrometry at the ISOLDE-PSB facility using laser ionization and mass separation. The results for the Ga-61 half-life and the Q(EC) value are 168(3) ms and 9255(50) keV, respectively. The beta-decay strength to the ground and low-lying excited states of the daughter Zn-61 was deduced. The experimental results are in a good agreement with large-scale shell-model calculations.
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| 6. |
- Adcox, K, et al.
(author)
-
Event-by-event fluctuations in mean p(T) and mean E(T) in root s(NN)=130 GeVAu+Au collisions
- 2002
-
In: Physical Review C (Nuclear Physics). - 0556-2813. ; 66:2
-
Journal article (peer-reviewed)abstract
- Distributions of event-by-event fluctuations of the mean transverse momentum and mean transverse energy near mid-rapidity have been measured in Au+Au collisions at roots(NN)=130 GeV at the Relativistic Heavy-Ion Collider. By comparing the distributions to what is expected for statistically independent particle emission, the magnitude of nonstatistical fluctuations in mean transverse momentum is determined to be consistent with zero. Also, no significant nonrandom fluctuations in mean transverse energy are observed. By constructing a fluctuation model with two event classes that preserve the mean and variance of the semi-inclusive p(T) or e(T) spectra, we exclude a region of fluctuations in roots(NN)=130 GeV Au+Au collisions.
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| 7. |
- Adler, SS, et al.
(author)
-
J/psi production in Au-Au collisions at root s(NN)=200 GeV
- 2004
-
In: Physical Review C (Nuclear Physics). - 0556-2813. ; 69:1
-
Journal article (peer-reviewed)abstract
- First results on charm quarkonia production in heavy ion collisions at the Relativistic Heavy Ion Collider (RHIC) are presented. The yield of J/psi's measured in the PHENIX experiment via electron-positron decay pairs at midrapidity for Au-Au reactions at roots(NN) = 200 GeV is analyzed as a function of collision centrality. For this analysis we have studied 49.3x10(6) minimum bias Au-Au reactions. We present the J/psi invariant yield dN/dy for peripheral and midcentral reactions. For the most central collisions where we observe no signal above background, we quote 90% confidence level upper limits. We compare these results with our J/psi measurement from proton-proton reactions at the same energy. We find that our measurements are not consistent with models that predict strong enhancement relative to binary collision scaling.
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| 8. |
- Aggarwal, MM, et al.
(author)
-
Centrality dependence of charged-neutral particle fluctuations in 158A (GeVPb)-Pb-208+Pb-208 collisions
- 2003
-
In: Physical Review C (Nuclear Physics). - 0556-2813. ; 67:4
-
Journal article (peer-reviewed)abstract
- Results on the study of localized fluctuations in the multiplicity of charged particles and photons produced in 158A GeV/c Pb+Pb collisions are presented for varying centralities. The charged versus neutral particle multiplicity correlations in common phase space regions of varying azimuthal sizes are analyzed by two different methods. Various types of mixed events are constructed to probe fluctuations arising from different sources. The measured results are compared to those from simulations and from mixed events. The comparison indicates the presence of nonstatistical fluctuations in both the charged particle and photon multiplicities in limited azimuthal regions. However, no correlated charged-neutral fluctuations, a possible signature of formation of disoriented chiral condensates, are observed. An upper limit on the production of disoriented chiral condensates is set.
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| 9. |
- Aggarwal, MM, et al.
(author)
-
Event-by-event fluctuations in particle multiplicities and transverse energy produced in 158A GeVPb plus Pb collisions
- 2002
-
In: Physical Review C (Nuclear Physics). - 0556-2813. ; 65:5
-
Journal article (peer-reviewed)abstract
- Event-by-event fluctuations in the multiplicities of charged particles and photons, and the total transverse energy in 158A GeV Pb+Pb collisions are studied for a wide range of centralities. For narrow centrality bins the multiplicity and transverse energy distributions are found to be near perfect Gaussians. The effect of detector acceptance on the multiplicity fluctuations has been studied and demonstrated to follow statistical considerations. The centrality dependence of the charged particle multiplicity fluctuations in the measured data has been found to agree reasonably well with those obtained from a participant model. However, for photons the multiplicity fluctuations have been found to be lower compared to those obtained from a participant model. The multiplicity and transverse energy fluctuations have also been compared to those obtained from the VENUS event generator.
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| 10. |
- Algora, A., et al.
(author)
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Pronounced Shape Change Induced by Quasiparticle Alignment
- 2000
-
In: Physical Review C (Nuclear Physics). - 0556-2813 .- 1089-490X. ; 61:3
-
Journal article (peer-reviewed)abstract
- Mean lifetimes of high-spin states of Kr-74 have been determined using the Doppler-shift attenuation method. The high-spin states were studied using the Ca-40(Ca-40, alpha 2p) reaction at a beam energy of 160 MeV with the GASP gamma-ray spectrometer. The ground-state band and negative parity side band show the presence of three different configurations in terms of transitional quadrupole deformations. A dramatic shape change was found along the ground-state band after the S-band crossing. The deduced quadrupole deformation changes are well reproduced by cranked Woods-Saxon Strutinsky calculations.
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| 11. |
- Andreoiu, Corina, et al.
(author)
-
Yrast Superdeformed Band in 59Cu
- 2000
-
In: Physical Review C (Nuclear Physics). - 0556-2813. ; 62:5, s. 513011-513015
-
Journal article (peer-reviewed)abstract
- High-spin states in 59Cu were populated using the fusion-evaporation reactions 28Si+40Ca at a beam energy of 125 MeV and 36Ar+28Si at a beam energy of 143 MeV. The Gammasphere array in conjunction with ancillary detector systems allowed for the identification of a superdeformed rotational band in 59Cu, which was firmly linked to low-spin yrast states. Using directional correlations of oriented states, a spin-parity assignment of Iπ = 25/2+ to the band head was possible. The average quadrupole moment of the band is measured to be Qt = (2.24±0.40) e b. The characteristics of the band are compared to neighboring nuclei and predictions of different mean-field theories.
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| 12. |
- Andreyev, A. N., et al.
(author)
-
In-beam and alpha-decay spectroscopy of Po-191 and evidence for triple shape coexistence at low energy in the daughter nucleus Pb-187
- 2002
-
In: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 66:1
-
Journal article (peer-reviewed)abstract
- Prompt gamma rays have been observed for the first time from the neutron-deficient nucleus Po-191 using the recoil-decay tagging technique at the RITU gas-filled separator. In addition improved alpha decay data have been measured for Po-191 and its daughter product Pb-187. The complementary gamma- and alpha-decay data point to the onset of oblate deformation in the light odd-mass Po nuclei by approaching the neutron midshell at N=104. The pattern of the favored and unfavored states observed on top of the 13/2(+) isomer in Po-191 indicates a change from the weak-coupling towards the strong-coupling scheme in Po-191m. In the daughter nucleus Pb-187, the 13/2(+) and 3/2(-) isomeric states become degenerate within the experimental accuracy. Evidence for triple shape coexistence at low energy has been found in the high-spin isomer in Pb-187. The results are supported by potential-energy surface calculations and by particle-plus-rotor calculations.
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| 13. |
- Andreyev, A. N., et al.
(author)
-
Shape-changing particle decays of Bi-185 and structure of the lightest odd-mass Bi isotopes
- 2004
-
In: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 69:5, s. 054308-
-
Journal article (peer-reviewed)abstract
- Proton and alpha decay of the proton-rich nuclide Bi-185 has been restudied in more detail in the complete fusion reaction Nb-93(Mo-95, 3n)Bi-185 at the velocity filter SHIP. The observed decay pattern of Bi-185 and of the heavier odd-mass isotopes Bi-187,Bi-189,Bi-191,Bi-193 are interpreted based on potential-energy surface calculations. It is shown that the experimental systematics of the particle decays and of the excited states in these nuclei (where known) can be explained by the prolate-oblate shape co-existence at low excitation energy. The observed state in Bi-185 is proposed to be of prolate nature, which is in contrast with the previously proposed oblate interpretation.
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| 14. |
- Asztalos, S. J., et al.
(author)
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Isotopic yields of neutron-rich nuclei from deep-inelastic reactions
- 2000
-
In: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 6101:1
-
Journal article (peer-reviewed)abstract
- We follow up on our earlier work involving a light projectile (Ca-48) to populate high spin states in neutron-rich nuclei with results from experiments involving a heavier projectile (Sm-154) fur the purposes of studying isotopic yields. These yields, which in some cases were mensurable down to a level of 0.1 of the total reaction cross section, are presented from three separate reactions. A trend in the isotopic yields towards N/Z equilibration is observed in one experiment having a large disparity in N/Z ratios between the projectile and target. In the two other reactions, where the N/Z driving force is less pronounced, the yields are instead clustered around the projectile and target nuclei. We present correlated projectilelike and targetlike fragment isotopic yields derived from gamma-gamma coincidences, a technique that enables one to partition the yield of an isotope according to the amount of neutron evaporation. Using this method we find that for the zero-neutron evaporation channel transfer occurs predominantly into the light fragment, consistent with the nature of the deep-inelastic mechanism. We further find that multiple-neutron evaporation contributes substantially to the yields of the isotopes.
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| 15. |
- Ban, Shufang, et al.
(author)
-
Density dependencies of interaction strengths and their influences on nuclear matter and neutron stars in relativistic mean field theory
- 2004
-
In: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 69:4
-
Journal article (peer-reviewed)abstract
- The density dependencies of various effective interaction strengths in the relativistic mean field are studied and carefully compared for nuclear matter and neutron stars. The influences of different density dependencies are presented and discussed on mean field potentials, saturation properties for nuclear matter, equations of state, maximum masses, and corresponding radii for neutron stars. Though the interaction strengths and the potentials given by various interactions are quite different in nuclear matter, the differences of saturation properties are subtle, except for NL2 and TM2, which are mainly used for light nuclei, while the properties by various interactions for pure neutron matter are quite different. To get an equation of state for neutron matter without any ambiguity, it is necessary to constrain the effective interactions either by microscopic many-body calculations for the neutron matter data or the data of nuclei with extreme isospin. For neutron stars, the interaction with large interaction strengths give strong potentials and large Oppenheimer-Volkoff (OV) mass limits. The density-dependent interactions DD-ME1 and TW-99 favor a large neutron population due to their weak rho-meson field at high densities. The OV mass limits calculated from different equations of state are 2.02-2.81M, and the corresponding radii are 10.78-13.27 km. After the inclusion of the hyperons, the corresponding values become 1.52-2.06M and 10.24-11.38 km.
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| 16. |
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| 17. |
- Bearden, IG, et al.
(author)
-
Particle production in central Pb+Pb collisions at 158A GeV/c
- 2002
-
In: Physical Review C (Nuclear Physics). - 0556-2813. ; 66:4
-
Journal article (peer-reviewed)abstract
- The NA44 experiment has measured single-particle inclusive spectra for charged pions, kaons, and protons as a function of transverse mass near midrapidity in 158A GeV/c Pb+Pb collisions. From the particle mass dependence of the observed m(T) distributions, we are able to deduce a value of about 120 MeV for the temperature at thermal freeze-out. From the observed ratios of the rapidity densities, we find values of the chemical potentials for light and strange quarks and a chemical freeze-out temperature of approximately 140 MeV.
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| 18. |
- Blazhev, A., et al.
(author)
-
Observation of a core-excited E4 isomer in Cd-98
- 2004
-
In: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 69
-
Journal article (peer-reviewed)abstract
- A core-excited I-pi=(12(+)) spin-gap isomer was identified in Cd-98 in an experiment at EUROBALL IV. It was found to feed the known I-pi=(8(+)) seniority isomer by an E4 transition. Half-lives of T-1/2=0.23 ((+4)(-3)) mus and 0.17 ((+6)(-4)) mus were measured for the two states at E-x=6635 keV and 2428 keV, respectively. From the excitation energy of the core-excited isomer a Sn-100 shell gap of 6.46(15) MeV is inferred. The measured E4 and E2 strengths, Sn-100 core excitations and the origin of empirical polarization charges are discussed in the framework of large-scale shell model calculations. An E2 polarization charge for protons of deltae(pi)
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| 19. |
- Blideanu, V., et al.
(author)
-
Nucleon-induced reactions at intermediate energies : New data at 96 MeV and theoretical status
- 2004
-
In: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 70:1, s. 014607-
-
Journal article (peer-reviewed)abstract
- Double-differential cross sections for light charged particle production (up to A=4) were measured in 96 MeV neutron-induced reactions, at the TSL Laboratory Cyclotron in Uppsala (Sweden). Measurements for three targets, Fe, Pb, and U, were performed using two independent devices, SCANDAL and MEDLEY. The data were recorded with low-energy thresholds and for a wide angular range (20°–160°). The normalization procedure used to extract the cross sections is based on the np elastic scattering reaction that we measured and for which we present experimental results. A good control of the systematic uncertainties affecting the results is achieved. Calculations using the exciton model are reported. Two different theoretical approaches proposed to improve its predictive power regarding the complex particle emission are tested. The capabilities of each approach is illustrated by comparison with the 96 MeV data that we measured, and with other experimental results available in the literature.
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| 20. |
- Bruce, A. M., et al.
(author)
-
Two-neutron alignment and shape changes in As-69
- 2000
-
In: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 6202:2
-
Journal article (peer-reviewed)abstract
- The nucleus As-69 was Studied using the Ca-40(S-32,3p)As-69 reaction at a beam energy of 105 MeV. An extension of the band built on the g(9/2) orbital was observed to exhibit a band crossing at a rotational frequency of 0.511 MeV with an associated alignment of 7 (h) over bar. This alignment is interpreted as being due to a pair of g(9/2) neutrons. Total Routhian surface calculations have been carried out which confirm that the shape of this nucleus changes from oblate at low spin to a triaxial prolate shape at intermediate spin.
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| 21. |
- Cardona, R., et al.
(author)
-
High-spin structure of normal-deformed bands in 84Zr
- 2003
-
In: Physical Review C - Nuclear Physics. - 0556-2813. ; 68, s. 1-024303
-
Journal article (peer-reviewed)abstract
- The reaction 58Ni(32S, α2p) at E lab= 135 MeV was used to populate high-spin states in 84Zr. The complete GAMMASPHERE and MICROBALL arrays were used to obtain clean γ- γ- γ line shapes to be analyzed by the Doppler shift attenuation method and to determine 27 lifetimes in the ground-state band and in two excited bands. Side-feeding times were also measured by comparing the line shapes gated with transitions above and below the state under study. The deduced electric quadrupole moments for the ground-state band are consistent with a very slow reduction with frequency with values ranging between 2.4(3) and 2.0(1)e b. The negative-parity bands feature also an approximate constancy of quadrupole moment with values similar to those in the ground-state band. Cranking calculations agree with this behavior in both parity bands and suggest an interpretation of the upper states in the ground-state band as part of a very slowly terminating band. Shell-dependent cranked Nilsson calculations explain a fourth γ cascade as pertaining to a noncollective structure terminating at I = 20+.
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| 22. |
- Carlsson, Gillis, et al.
(author)
-
Nuclear shell structure and rotational bands in Nb-86
- 2004
-
In: Physical Review C (Nuclear Physics). - 0556-2813. ; 70:2
-
Journal article (peer-reviewed)abstract
- The high spin structures in Nb-86 are analyzed using the cranked Nilsson-Strutinsky model. Energy versus spin curves as well as deformations and electric transition quadrupole moments are considered. It is concluded that different single-particle parameters compared with the standard values lead to better agreement with recent experimental results.
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| 23. |
- Chiara, CJ, et al.
(author)
-
Transition Quadrupole Moments in the Superdeformed Band of 40Ca
- 2003
-
In: Physical Review C (Nuclear Physics). - 0556-2813. ; 67:4
-
Journal article (peer-reviewed)abstract
- The transition quadrupole moments Q(t) for the superdeformed band in Ca-40 have been determined through thin-target Doppler-shift attenuation analyses. A best-fit value of Q(t)=1.30+/-0.05 e b is obtained when a single value is assumed for the entire band. Fitting separate quadrupole moments for in-band transitions decaying from the high-spin states and the presumably admixed low-spin states results in Q(t)(high)= 1.81(-0.26)(+0.41) e b and Q(t)(low)=1.18(-0.05)(+0.06) e b, respectively. Q(t) values extracted for individual transitions in a Doppler-broadened line-shape analysis also indicate smaller Q(t) values at lower spins. These results are consistent with the interpretation of this band as an eight-particle-eight-hole superdeformed band with a significant admixture of less-collective configurations at low spins.
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| 24. |
- Daehnick, W.W, et al.
(author)
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Spin correlations in polarized p polarized p -> p n pi+ production near threshold
- 2002
-
In: Physical Review C. Nuclear Physics. - : American Physical Society. - 0556-2813 .- 1089-490X. ; 65, s. 024003-1
-
Journal article (peer-reviewed)abstract
- A first measurement of longitudinell as well as transverse spin correlation coefficients for the reaction pp->pn pi+ is made using a polarized proton target and a polarized proton beam. We report kinematically complete measurements for this reaction at 32
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| 25. |
- Delion, D. S., et al.
(author)
-
High-spin proton emitters in odd-odd nuclei and shape changes
- 2003
-
In: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 68:5, s. 054603-
-
Journal article (peer-reviewed)abstract
- We present a formalism to describe proton emission from odd-odd nuclei based on a scatteringlike approach. Special emphasis is given to the case of transitions between states with different deformations. As an example we estimate the proton half-life of the odd-odd nucleus Cu-58 . Our calculations show that the change of deformation in the decay process has a significant influence on the half life. In addition, the angular momentum coupling of proton and neutron orbitals can result in an additional K hindrance of the decay. To fully account for the observed half life in Cu-58 , we propose shape mixing of the final state.
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| 26. |
- Delion, D. S., et al.
(author)
-
Proton emission from triaxial nuclei
- 2004
-
In: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 70:6, s. 061301-
-
Journal article (peer-reviewed)abstract
- Proton decay from triaxially deformed nuclei is investigated. The deformation parameters corresponding to the mother nucleus are determined microscopically and the calculated decay widths are used to probe the mean-field wave function. The proton wave function in the mother nucleus is described as a resonant state in a coupled-channel formalism. The decay width, as well as the angular distribution of the decaying particle, are evaluated and their dependence upon the triaxial deformation parameters is studied in the decay of Re-161 and Bi-185. It is found that the decay width is very sensitive to the parameters defining the triaxial deformation while the angular distribution is a universal function which does not depend upon details of the nuclear structure.
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| 27. |
- Devlin, M., et al.
(author)
-
Yrast Spectroscopy of 54Cr
- 2000
-
In: Physical Review C (Nuclear Physics). - 0556-2813. ; 61:1
-
Journal article (peer-reviewed)abstract
- High-spin levels in the heaviest stable isotope of chromium were observed following the fusion-evaporation reaction C-12(Ca-48, alpha 2n)Cr-54 at a beam energy of 157 MeV, using the GAMMASPHERE and MICROBALL detector arrays. Numerous yrast and near yrast levels are reported, and previously assigned 7(+) and 9(+) levels are suggested to be 5(+) and 7(+), respectively. The inferred level scheme is compared with shell model calculations.
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| 28. |
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| 29. |
- Dobaczewski, J., et al.
(author)
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T=0 neutron-proton pairing correlations in the superdeformed rotational bands around Zn-60
- 2003
-
In: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 67:3, s. 343081-3430810
-
Journal article (peer-reviewed)abstract
- The superdeformed bands in Cu-58, Cu-59, Zn-60, and Zn-61 are analyzed within the frameworks of the Skyrme-Hartree-Fock as well as Strutinsky-Woods-Saxon total Routhian surface methods with and without T = 1 pairing correlations between like particles. It is shown that a consistent description within these standard approaches cannot be achieved. A T = 0 neutron-proton pairing configuration mixing of signature-separated bands in Zn-60 is suggested as a possible solution to the problem.
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| 30. |
- Dutta, D, et al.
(author)
-
Nuclear transparency with the gamma n ->pi(-)p process in He-4
- 2003
-
In: Physical Review C (Nuclear Physics). - 0556-2813. ; 68:2: 021001
-
Journal article (peer-reviewed)abstract
- We have measured the nuclear transparency of the fundamental process gamman-->pi(-)p in He-4. These measurements were performed at Jefferson Lab in the photon energy range of 1.6-4.5 GeV and at theta(cm)(pi)=70degrees and 90degrees. These measurements are the first of their kind in the study of nuclear transparency in photoreactions. They also provide a benchmark test of Glauber calculations based on traditional models of nuclear physics. The transparency results suggest deviations from the traditional nuclear physics picture. The momentum transfer dependence of the measured nuclear transparency is consistent with Glauber calculations that include the quantum chromodynamics phenomenon of color transparency.
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| 31. |
- Döring, J., et al.
(author)
-
Band terminations in the valence space of 86Zr
- 2000
-
In: Physical Review C - Nuclear Physics. - 0556-2813. ; 61:3, s. 343101-343106
-
Journal article (peer-reviewed)abstract
- High-spin states in 86Zr up to 30+ and 27- were observed via the 58Ni(32S,4p) reaction at 135 MeV beam energy using the combined GAMMASPHERE and MICROBALL systems. Calculations performed with the configuration-dependent shell-correction approach show that these states are built from six g9/2 neutrons and at most four protons excited from the p1/2,p3/2,f5/2 subshells to the g9/2 subshell at small deformation. The highest observed states at 27- and 30+ are interpreted as band-terminating states with the latter having the highest spin available in the valence space for 86Zr.
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| 32. |
- Ekman, Jörgen, et al.
(author)
-
Core Excited States in the A=51 Mirror Nuclei
- 2004
-
In: Physical Review C (Nuclear Physics). - 0556-2813. ; 70:5
-
Journal article (peer-reviewed)abstract
- Three previously unknown high-energy gamma-ray transitions between 4.2 and 5.4 MeV were identified in the T-z=-1/2 nucleus Fe-51 following the fusion-evaporation reaction S-32(Si-28, 2alpha1n)Fe-51. These transitions represent decays of core excited states. The gamma rays were detected in the Ge detector array Gammasphere combined with the neutron detector system Neutron Shell and the charged-particle array Microball. The three transitions are related to the mirror transitions in the T-z= + 1 /2 nucleus Mn-51, and the resulting mirror-energy difference diagram is discussed with predictions from large-scale shell-model calculations.
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| 33. |
- Ekman, Jörgen, et al.
(author)
-
Evidence for a 1g9/2 Rotational Band in 51Mn
- 2002
-
In: Physical Review C (Nuclear Physics). - 0556-2813. ; 66:5, s. 513011-513015
-
Journal article (peer-reviewed)abstract
- A terminating rotational band has been identified in Mn-51 following the Si-28(S-32,2alpha1p)Mn-51 fusion-evaporation reaction at 130 MeV beam energy. Spins and tentative positive parities of the band members are assigned based on angular distribution and correlation measurements of transitions, which connect the rotational structure with previously known yrast states. Configuration-dependent cranked Nilsson-Strutinsky calculations suggest a configuration of the band, which comprises one particle in the 1g(9/2) intruder orbit.
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| 34. |
- Ekman, Jörgen, et al.
(author)
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Gamma-ray Spectroscopy of Core-excited States in 51Mn
- 2004
-
In: Physical Review C (Nuclear Physics). - 0556-2813. ; 70:1
-
Journal article (peer-reviewed)abstract
- The level scheme of Mn-51 has been investigated using the Si-28(S-32 2alpha1p)Mn-51 fusion-evaporation reaction at 125 MeV beam energy. The gamma rays were detected in the Ge-detector array Gammasphere, which was coupled to the 4pi-charged-particle detector Microball and the Neutron Shell for the coincident detection of evaporated particles. Over 100 new gamma-ray transitions connecting some 50 excited states have been identified. Most of the states are built on particle-hole excitations across the shell gaps at particle number N=Z=28. The rich experimental data allows for a 'comprehensive comparison of core-excited states with results from large-scale shell-model calculations, which are known to provide excellent predictions for the lower-lying yrast and near-yrast levels in 1f(7/2) nuclei.
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| 35. |
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| 36. |
- Fahlander, Claes, et al.
(author)
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Excited States in 103Sn: Neutron Single-particle Energies with Respect to 100Sn
- 2001
-
In: Physical Review C (Nuclear Physics). - 0556-2813 .- 1089-490X. ; 63:2
-
Journal article (peer-reviewed)abstract
- Gamma-ray lines from Sn-103 have been identified for the first time using EUROBALL and ancillary detectors. The level scheme of Sn-103 has been established by means of particle-gated gamma gamma coincidences. The energy spacing between the g(7/2) and d(5/2) neutron single-particle orbitals is determined from the excited states in Sn-103.
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| 37. |
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| 38. |
- Gayou, O., et al.
(author)
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Measurements of the elastic electromagnetic form factor ratio μpGEp/GMp via polarization transfer
- 2001
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In: Physical Review C: covering nuclear physics. - 2469-9985. ; 64:3
-
Journal article (peer-reviewed)abstract
- We present measurements of the ratio of the proton elastic electromagnetic form factors, μpGEp/GMp. The Jefferson Lab Hall A Focal Plane Polarimeter was used to determine the longitudinal and transverse components of the recoil proton polarization in ep elastic scattering; the ratio of these polarization components is proportional to the ratio of the two form factors. These data reproduce the observation of Jones et al. [Phys. Rev. Lett. 84, 1398 (2000)], that the form factor ratio decreases significantly from unity above Q2=1GeV2.
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| 39. |
- Ghetti, R., et al.
(author)
-
Influence of multiple sources on the two-neutron correlation function in Ni-induced, intermediate energy, heavy ion reactions
- 2001
-
In: Physical Review C. Nuclear Physics. - : American Physical Society. - 0556-2813 .- 1089-490X. ; 64:1
-
Journal article (peer-reviewed)abstract
- The strength of the neutron-neutron correlation function from the E=45AMeV58Ni+27Al, natNi, and 197Au reactions depends on the neutron parallel velocity. This indicates the presence of multiple sources of neutron emission. We find these sources consistent with a dissipative, binary reaction mechanism as it is described by, e.g., Boltzmann-Uehling-Uhlenbeck calculations.
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| 40. |
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| 41. |
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| 42. |
- Ghetti, Roberta, et al.
(author)
-
Isospin effects on two-particle correlation functions in E/A=61 MeV Ar-36+Sn-112,Sn-124 reactions
- 2004
-
In: Physical Review C (Nuclear Physics). - 0556-2813. ; 69:3
-
Journal article (peer-reviewed)abstract
- Small-angle, two-particle correlation functions have been measured for Ar-36+Sn-112,Sn-124 collisions at E/A=61 MeV. Total momentum gated neutron-proton (np) and proton-proton (pp) correlations are stronger for the Sn-124 target. Some of the correlation functions for particle pairs involving deuterons or tritons (nd, pt, and nt) also show a dependence on the isospin of the emitting source.
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| 43. |
- Ghetti, Roberta, et al.
(author)
-
Two-particle correlation functions in projectilelike emission experiments at very forward angles
- 2004
-
In: Physical Review C (Nuclear Physics). - 0556-2813. ; 70:2
-
Journal article (peer-reviewed)abstract
- Projectilelike fragment emission is studied via two-particle correlation functions, constructed from coincidence data detected at very forward angles (0.7degreesless than or equal totheta(lab)less than or equal to7degrees) in the E/A=44 and 77 MeV Ar-40+Al-27 reactions. The shape of the proton-proton correlation function is unexpected. Possible origins of this effect are discussed and a way to reestablish the expected shape is presented.
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| 44. |
- Gladnishki, KA, et al.
(author)
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Angular Momentum Population in the Projectile Fragmentation of 238U at 750 MeV/nucleon
- 2004
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In: Physical Review C (Nuclear Physics). - 0556-2813. ; 69:2
-
Journal article (peer-reviewed)abstract
- A systematic study of the population probabilities of nanosecond and microsecond isomers produced following the projectile fragmentation of U-238 at 750 MeV/nucleon has been undertaken at the SIS/FRS facility at GSI. Approximately 15 isomeric states in neutron-deficient nuclei around A similar to 190 were identified and the corresponding. isomeric ratios determined. The results are compared with a model based on the statistical abrasion-ablation description of relativistic fragmentation and simple assumptions concerning gamma cascades in the final nucleus (sharp cutoff). This model represents an upper limit for the population of isomeric states in relativistic projectile fragmentation. When the decay properties of the states above the isomer are taken into account, as opposed to the sharp cutoff approximation, a good agreement between the experimental and calculated angular momentum population is obtained.
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| 45. |
- Gorgen, A, et al.
(author)
-
Quadrupole moments of wobbling excitations in Lu-163
- 2004
-
In: Physical Review C (Nuclear Physics). - 0556-2813. ; 69:3
-
Journal article (peer-reviewed)abstract
- Lifetimes of states in the triaxial strongly deformed bands of Lu-163 have been measured with the Gammasphere spectrometer using the Doppler-shift attenuation method. The bands have been interpreted as wobbling-phonon excitations from the characteristic electromagnetic properties of the transitions connecting the bands. Quadrupole moments are extracted for the zero-phonon yrast band and, for the first time, for the one-phonon wobbling band. The very similar results found for the two bands suggest a similar intrinsic structure and support the wobbling interpretation. While the in-band quadrupole moments for the bands show a decreasing trend towards higher spin, the ratio of the interband to the in-band transition strengths remains constant. Both features can be understood by a small increase in triaxiality towards higher spin. Such a change in triaxiality is also found in cranking calculations, to which the experimental results are compared.
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| 46. |
- Greiff, J, et al.
(author)
-
Pion production in dp -> dN pi reactions with deuteron projectiles - art. no. 064002
- 2000
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In: PHYSICAL REVIEW C. - : AMERICAN PHYSICAL SOC. - 0556-2813. ; 6206:6, s. 4002-
-
Journal article (peer-reviewed)abstract
- Kinematically complete events have been studied for the reactions dp-->dp pi (0) and dp-->dn pi (+) at projectile energies between 437 and 559 MeV. The measurement covers a range of pion momenta eta =p(pi ,c.m.)(max)/m(pi)c from near the production thresh
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| 47. |
- Gueorguieva, E., et al.
(author)
-
High-spin states in Au-191 : Evidence for triaxial shape?
- 2003
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In: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 68:5, s. 543081-5430814
-
Journal article (peer-reviewed)abstract
- The level scheme of Au-191 was considerably extended to high spin using gamma spectroscopy with the Eurogam-II array and internal conversion measurements with the Orsay electron spectrometer. Several bands that appear as strongly coupled were associated with low- Omega configurations in Au-191 . Using total routhian surface and cranked shell model calculations it was shown that these bands have a rotation-aligned nature and are most likely generated by the nonaxiallity of the nucleus induced by the odd proton. The predictions for the presence of such bands in Au-191 and in the oblate nuclei in the Pt-Au-Hg region found excellent agreement with the experimental data, as well as the predictions for their alignments and band-crossing frequencies in Au-191 .
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| 48. |
- Gueorguieva, E., et al.
(author)
-
Sets of rotation-aligned bands indicating nonaxiality in Au-190
- 2004
-
In: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 69:4, s. 044320-
-
Journal article (peer-reviewed)abstract
- The level scheme of Au-190 was extended up to high spin using gamma spectroscopy with the Eurogam-II array and internal conversion measurements with the electron- gamma spectrometer of Orsay. Several sets of rotation-aligned bands were found and associated with high- j, low- K configurations. According to the total Routhian surface and cranked shell model calculations these bands are caused by the nonaxiality of the nuclear deformation (gammaless than or equal to-70degrees). Furthermore, very good agreement was obtained between the experimental data and the theoretical predictions for the properties of these bands, such as alignments, band-crossing frequencies, and signature inversion, thus supporting the suggested nonaxial shapes.
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| 49. |
- Hadinia, Baharak, et al.
(author)
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First identification of gamma-ray transitions in 107Te
- 2004
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In: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 70:6, s. 064314-1-064314-4
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Journal article (peer-reviewed)abstract
- Gamma-ray transitions in Te-107 have been identified for the first time. The experiment, which utilized the recoil decay tagging technique, was performed at the accelerator laboratory of the University of Jyvaskyla, Finland. Prompt gamma rays produced in Ni-58(Cr-52,3n)Te-107(*) reactions were detected by the JUROGAM gamma-ray spectrometer. The gamma rays belonging to Te-107 were selected based on the recoil identification provided by the RITU gas-filled recoil separator and the GREAT focal plane spectrometer. A first excited state at 90 keV, tentatively of g(7/2) character, is proposed.
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| 50. |
- Hamamoto-Kuroda, Ikuko
(author)
-
Dominance of low-l component in weakly bound deformed single-neutron orbits
- 2004
-
In: Physical Review C (Nuclear Physics). - 0556-2813. ; 69:4
-
Journal article (peer-reviewed)abstract
- Calculating single-particle (Nilsson) levels in axially symmetric quadrupole-deformed potentials in coordinate space, the structure of weakly bound neutron orbits is studied in the absence of pair correlation. It is shown that in the wave functions of Omega(pi)=1/2(+) orbits, where Omega expresses the projection of the particle angular momentum along the symmetry axis, the l=0 (s(1/2)) component becomes overwhelmingly dominant as the binding energy of the orbits approaches zero, irrespective of the size of the deformation and the kind of Nilsson orbits. Consequently, all Omega(pi)=1/2(+) levels become practically unavailable for both deformation and many-body pair correlation, when the levels approach continuum or lie in the continuum.
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