Physical Review C

We report a measurement of the differential cross section for the γn→π^-p process from the CLAS detector at Jefferson Laboratory in Hall B for photon energies between 1.0 and 3.5 GeV and pion center-of-mass (c.m.) angles (θ_c.m.) between 50° and 115°. We confirm a previous indication of a broa...

We present the self-consistent, nonperturbative analysis of isospin mixing using the nuclear density functional approach and the rediagonalization of the Coulomb interaction in the good-isospin basis. The unphysical isospin violation on the mean-field level, caused by the neutron excess, is eliminat...

The double-differential cross sections for the ⁴⁸Ca(p,n) and ⁴⁸Ti(n,p)/span> reactions were measured at 300 MeV. A multipole decomposition technique was applied to the spectra to extract the Gamow-Teller (GT) components. The integrated GT strengths up to an excitation energy of 30 MeV in ⁴⁸Sc are 15.3±...

The 1789 keV state in ³⁰Mg was identified as the first excited 0⁺ state via its electric monopole (E0) transition to the ground state. The measured small value of ρ²(E0,0₂⁺→0₁⁺)=(26.2±7.5)×10^-3 implies within a two-level model a small mixing of competing configurations with largely different i...

We determine the Galactic production rate of strangelets as a canonical input to calculations of the measurable cosmic ray flux of strangelets by performing simulations of strange star mergers and combining the results with recent estimates of stellar binary populations. We find that the flux depend...

A neutron or proton excess in nuclei leads to an isovector-vector mean field which, through its coupling to the quarks in a bound nucleon, implies a shift in the quark distributions with respect to the Bjorken scaling variable. We show that this result leads to an additional correction to the NuTeV ...

The nuclides ^104–108Sn, ^106–110Sb, ^108,109Te, and ¹¹¹I at the expected endpoint of the astrophysical rp process have been produced in ⁵⁸Ni+^natNi fusion-evaporation reactions at IGISOL and their mass values were precisely measured with the JYFLTRAP Penning trap mass spectrometer. For ¹⁰⁶Sb, sup>108Sb...

In recent years, many heavy mesons and charmonia were observed which do not fit in the conventional quark model expectations. Some of them are proposed to be hadronic molecules. Here we investigate the consequences of heavy-quark spin symmetry on these heavy-meson hadronic molecules. Heavy-quark spi...

The lifetimes of the first excited states of the N=30 isotones ⁵⁰Ca and ⁵¹Sc have been determined using the Recoil Distance Doppler Shift method in combination with the CLARA-PRISMA spectrometers. This is the first time such a method is applied to measure lifetimes of neutron-rich nuclei populated v...

We present the first Gogny-Hartree-Fock-Bogoliubov (HFB) model which reproduces nuclear masses with an accuracy comparable with the best mass formulas. In contrast with the Skyrme-HFB nuclear-mass models, an explicit and self-consistent account of all the quadrupole correlation energies are included...

The ³He(α,γ)⁷Be reaction presently represents the largest nuclear uncertainty in the predicted solar neutrino flux and has important implications on the big bang nucleosynthesis, i.e., the production of primordial ⁷Li. We present here the results of an experiment using the recoil separator ERNA (E...

We have produced laser-cooled crystals of ²³²Th³⁺ in a linear rf Paul trap. This is the first time that a multiply charged ion has been laser cooled. Our work opens an avenue for excitation of the nuclear transition in a trapped, cold ²²⁹Th³⁺ ion. Laser excitation of nuclear states would establish a...

We report the first detailed study of the relative importance of the stripping and diffraction mechanisms involved in nucleon knockout reactions, by the use of a coincidence measurement of the residue and fast proton following one-proton knockout reactions. The measurements used the S800 spectrograp...

I study the diffuse flux of electron antineutrinos from stellar collapses with direct black hole formation (failed supernovae). This flux is more energetic than that from successful supernovae, and therefore it might contribute substantially to the total diffuse flux above realistic detection thresh...

The effects of strong longitudinal color electric fields on the open charm production in nucleus-nucleus (A+A) collisions at 200A  GeV are investigated within the framework of the HIJING/BB̅ v2.0 model. A threefold increase of the effective string tension due to in-medium effects in A+...

Two particle correlation data from the BNL Relativistic Heavy Ion Collider have provided detailed femtoscopic information describing pion emission. In contrast with the success of hydrodynamics in reproducing other classes of observables, these data had avoided description with hydrodynamic-based ap...

The NA60 experiment at the CERN Super Proton Synchrotron has studied dimuon production in 158A  GeV In-In collisions. The strong excess of pairs above the known sources found in the complete mass region 0.2lt;Mlt;2.6  GeV has previously been interpreted as thermal radiation. We now present...

A new method of optical pumping in an ion beam cooler buncher has been developed to selectively enhance ionic metastable state populations. The technique permits the study of elements previously inaccessible to laser spectroscopy and has been applied here to the study of Nb. Model independent mean-s...

The rotational band structure of ²⁵⁵Lr has been investigated using advanced in-beam γ-ray spectroscopic techniques. To date, ²⁵⁵Lr is the heaviest nucleus to be studied in this manner. One rotational band has been unambiguously observed and strong evidence for a second rotational structure was foun...

The atomic masses of ¹³⁰Te and ¹³⁰Xe have been obtained by measuring cyclotron frequency ratios of pairs of triply charged ions simultaneously trapped in a Penning trap. The results, with 1 standard deviation uncertainty, are M(¹³⁰Te)=129.906 222 744(16)   u and M(¹³⁰Xe)=129.903 509 3...

A Comment on the Letter by B. C. Liu and B. S. Zou, Phys. Rev. Lett. 96, 042002 (2006).

The gluonic contribution to the nuclear modification factor R_AA is investigated for central Au+Au collisions at sqrt[s] =200  AGeV employing a perturbative QCD-based parton cascade including radiative processes. A flat quenching pattern is found up to transverse momenta of 30 GeV, which is slig...

The effect of initial correlations between nucleons on the nuclear breakup mechanism is studied. A quantum transport theory which extends the standard mean-field approach is developed to incorporate short range pairing correlation as well as direct nucleon-nucleon collisions. A time evolution of the...

We show that if a flavorless vector meson remains bound after deconfinement, and if its limiting velocity in the quark-gluon plasma is subluminal, then this meson produces a distinct peak in the spectrum of thermal photons emitted by the plasma. We also demonstrate that this effect is a universal pr...

Mountains on rapidly rotating neutron stars efficiently radiate gravitational waves. The maximum possible size of these mountains depends on the breaking strain of the neutron star crust. With multimillion ion molecular dynamics simulations of Coulomb solids representing the crust, we show that the ...

Inclusive measurements of pion production in proton-proton collisions in the forward direction were undertaken at 400 and 600 MeV at the cooler synchrotron (COSY) at Forschungszentrum Julich using the Big Karl spectrograph. The high resolution in the π⁺ momentum ensured that there was an unambiguou...

The fission probability of ²³²U has been measured using the ²³¹Pa(³He,df) reaction with an energy resolution of 11 keV in the excitation energy region of E^*=4.0-6.4 MeV. A number of sub-barrier fission resonances have been observed for the first time in the excitation energy range below E^*=4.8 MeV a...

Two high-lying states in ¹⁵F and ¹⁶Ne, unbound with respect to one-proton (1p) and two-proton (2p) emissions, have been observed in the fragmentation of ¹⁷Ne at intermediate energies. They undergo mainly sequential emissions of protons via intermediate states in ¹⁴O and ¹⁵F and have decay energies o...

Photoabsorption cross sections σ_γ up to the neutron-separation energy S_n were measured for the stable even-mass isotopes ^92-100Mo in photon-scattering experiments. The photon-scattering data were analyzed in a novel way by taking into account the intensity of unresolved levels at high excitation e...

Chopped-beam techniques and γ-ray spectroscopy with Gammasphere have been used to measure the lifetime of the 1112-keV 8^- isomeric state in ¹⁷⁴Er. The value obtained of τ=5.8(4) s corresponds to a reduced hindrance of f_ν=98 for the 163-keV E1 transition to the 8⁺ state of the ground-state band, i...

Excited states of the neutron-deficient nucleus ¹⁷⁵Hg, populated using fusion-evaporation reactions, are reported for the first time. The spin and parity of the ground state has been determined to be I^π=7/2^- through measurements of the α decay to the daughter nucleus ¹⁷¹Pt. A structure based on an...

Neutron hole states in the exotic N=27 isotope ⁴⁴Cl have been populated using the intermediate-energy single-neutron knockout reaction ⁹Be(⁴⁵Cl,⁴⁴Cl)X. The momentum distribution of the residual ⁴⁴Cl nuclei after direct population of the ground state is consistent with removal of an l=1/span> neutron. This...

In view of recent data from the Thomas Jefferson National Accelerator Facility (JLab) on inclusive electron scattering off nuclei at high momentum transfer (Q²≳1 GeV²) and their current analysis, it is shown that, if the scaling variable is properly chosen, the analysis in terms of scaling funct...

α-particle (quartet) condensation in homogeneous spin-isospin symmetric nuclear matter is investigated. The usual Thouless criterion for the critical temperature is extended to the quartet case. The in-medium four-body problem is strongly simplified by the use of a momentum-projected mean-field ans...

The electromagnetic transitions of the doublet bands with different triaxiality parameter γ are discussed in the particle rotor model with πh_11/2⊗νh_11/2^-1 configuration. It is found that B(M1) staggering as well as the resulting B(M1)/B(E2) and B(M1)_in/B(M1)_out staggering are sensitive to the t...

We performed self-consistent Hartree-Fock plus random-phase approximation (HF+RPA) calculations for charge-exchange 1⁺ states in ⁹⁰Zr and ²⁰⁸Pb by using Skyrme interactions with tensor terms. We employed a parameter set in which the tensor terms are added to the SGII interaction. It is pointed out t...

We present evidence for a new supersymmetric quartet in the A~190 region of the nuclear mass table. New experimental information on transfer and neutron capture reactions to the odd-odd nucleus ¹⁹⁴Ir strongly suggests the existence of a new supersymmetric quartet, consisting of the ^192,193Os and ^193...

Gamma rays de-exciting isomeric states in the neutron-rich nucleus ₇₆¹⁹⁸Os₁₂₂ have been observed following relativistic projectile fragmentation of a 1 GeV per nucleon ²⁰⁸Pb beam. The ground-state band has properties compatible with oblate deformation. The evolution of the structure of Os isotopes c...

Excited states in ²⁵⁶Rf were populated via the ²⁰⁸Pb(⁵⁰Ti,2n) fusion–evaporation reaction. Delayed γ-ray and electron decay spectroscopy was performed and three isomeric states in ²⁵⁶Rf have been identified. A fourth low-energy nonyrast state was identified from the γ-ray decay of one of the hig...

Neutron and proton evaporation spectra from the ⁶Li+⁵⁵Mn and d+⁵⁹Co reactions have been analyzed with the Hauser-Feshbach approach using different input models for nuclear level densities of ⁶⁰Ni and ⁶⁰Co nuclei. It has been found that models with a Fermi-gas like temperature dependence fail to repr...

Internal conversion coefficients have been measured for transitions following the decay of the 32 μs isomer in the neutron-deficient isotope ¹⁸⁹Pb. The main branch at 337 keV to the 25/2⁺ excited state is shown to be of E3 multipolarity with a strength of about 24 W.u. This, together with multipola...

Neutrino-induced reactions on ⁵⁶Fe and ⁵⁶Ni are investigated based on a new shell-model Hamiltonian for pf shell. The calculated charged current reaction cross section on ⁵⁶Fe induced by decay-at-rest (DAR) neutrinos is shown to be consistent with the observation. The Gamow-Teller strength in ⁵⁶Ni i...

In heavy-ion collisions, isoscaling provides a method for studying the evolution of nuclear symmetry energy as a function of excitation energy. One challenge in using isoscaling is to accurately determine the neutron-to-proton ratio (N/Z) of the fragmenting source. Isoscaling results are presented f...

Precise measurements of the reaction cross sections (σ_R) for ¹²C on Be, C, and Al targets and ¹¹Be on Be targets were performed in the energy range between 30 and 400 MeV/nucleon. The energy dependencies of σ_R for ¹²C, ¹¹Be, and ⁸B were compared to Glauber-type calculations performed using reliabl...

Nuclear thermodynamic observables such as temperature, freeze-out volume, and specific heat as obtained from isotopic ratios in hot disassembled nuclear matter are examined in the light of the S-matrix approach to the nuclear equation of state. The values of the observables, as extracted without inc...

Complete fusion excitation function for the ⁶Li+¹⁴⁴Sm reaction has been measured at near barrier energies by the activation technique. Coupled-channel calculations show an enhancement in fusion cross section at energies below the barrier compared to the one-dimensional barrier penetration model calc...

The effect of the crystal lattice on nuclear fusion reactions p+d→³He taking place in internal conversion channels is studied. Fusionable particles solved in the investigated crystalline material form a sublattice. Fusion reaction is generated by a flux of incoming fusionable particles. The calcul...

The mass of ¹¹Li has been determined from Q-value measurements of the ¹H(¹¹Li,⁹Li)³H reaction. The experiment was performed at TRIUMF laboratory with the GANIL active target MAYA. Energy-energy and angle-angle kinematics reconstruction give a Q value of 8.119(22) MeV for the reaction. The derived ¹¹...

Based on a dynamical Langevin equation coupled with a statistical decay model, we calculate the excess of the prescission neutron multiplicity of the heavy nuclei ²⁴⁰Cf, ²⁴⁶Cf, ²⁵²Cf, and ²⁴⁰U over that predicted by the standard statistical model as a function of the postsaddle dissipation strength....

Relativistic Heavy Ion Collider experiments exhibit correlations peaked in relative azimuthal angle and extended in rapidity. Called the ridge, this peak occurs both with and without a jet trigger. We argue that the untriggered ridge arises when particles formed by flux tubes in an early Glasma stag...

We have implemented the Tsallis statistics in a Blast-Wave model (TBW) and applied it to midrapidity transverse-momentum spectra of identified particles measured at BNL Relativistic Heavy Ion Collider (RHIC). This new TBW function fits the RHIC data very well for p_Tlt;3 GeV/c. We observed that the ...

Nonmesonic decay of kaonic nuclei is investigated under a Λ(1405) doorway picture in which the K̅ absorptions in nuclei take place through the Λ(1405) resonance. Calculating Λ(1405)N→YN transitions with one-meson exchange, we find that the nonmesonic decay ratio Γ_ΛN/Γ_Σ⁰N depends s...

We study the leading electroweak corrections in the precision measurement of the strange form factors. Specifically, we calculate the two-boson exchange (TBE), two-photon exchange (TPE) plus γZ exchange (γZE), and corrections with Δ(1232) excitation to the parity-violating asymmetry of the elasti...

The Q_EC value of the superallowed β emitter ²⁶Si has been measured with the JYFLTRAP Penning trap facility to be 4840.85(10) keV which is ten times more precise than any previous measurement. This leaves only the branching ratio to be improved before the Ft value of ²⁶Si can be used to test the con...

Using a beam of the radioactive isotope ²⁵Al, produced with the new RESOLUT facility, we measured the direct (d,n) proton-transfer reaction leading to low-lying proton resonances in ²⁶Si. We observed the lowest l=0 proton resonance, identified with the 3⁺ state at 5.914-MeV excitation energy. This r...

The fission probability of ²³²U has been measured using the ²³¹Pa(³He,df) reaction with an energy resolution of 11 keV in the excitation energy region of E^*=4.0-6.4 MeV. A number of sub-barrier fission resonances have been observed for the first time in the excitation energy range below E^*=4.8 MeV a...

The nonlinear σ model that includes vector meson contributions is utilized for the study of nuclear matter. Here, the σ meson degree of freedom is eliminated by the condition that σ²+π² is invariant under both chiral transformation and isospin rotation. The nuclear matter consists of nucleons, p...

The nucleus ⁷⁷Ge was studied through the ⁷⁶Ge(¹³C,¹²C)⁷⁷Ge reaction at a sub-Coulomb energy. The angular distributions of γ rays depopulating excited states in ⁷⁷Ge were measured in order to constrain spin and parity assignments. Some of these assignments are of use in connection with neutrinoless ...

Two high-lying states in ¹⁵F and ¹⁶Ne, unbound with respect to one-proton (1p) and two-proton (2p) emissions, have been observed in the fragmentation of ¹⁷Ne at intermediate energies. They undergo mainly sequential emissions of protons via intermediate states in ¹⁴O and ¹⁵F and have decay energies o...

Photoabsorption cross sections σ_γ up to the neutron-separation energy S_n were measured for the stable even-mass isotopes ^92-100Mo in photon-scattering experiments. The photon-scattering data were analyzed in a novel way by taking into account the intensity of unresolved levels at high excitation e...

Chopped-beam techniques and γ-ray spectroscopy with Gammasphere have been used to measure the lifetime of the 1112-keV 8^- isomeric state in ¹⁷⁴Er. The value obtained of τ=5.8(4) s corresponds to a reduced hindrance of f_ν=98 for the 163-keV E1 transition to the 8⁺ state of the ground-state band, i...

The angular distributions of γ rays and α particles from oriented ²⁵⁰Bk, ^253,254Es, and ²⁵⁵Fm nuclei were investigated to extract hyperfine interaction information for these actinide impurities in an iron host lattice. The hyperfine field of einsteinium in iron was found to be |B_hf(EsFe̲ ...

The low lying states in ¹²⁸Ba have been investigated for the first time with the ¹³⁰Ba(p,t)¹²⁸Ba reaction. The experiment was performed at the Munich Q3D magnetic spectrograph with a 25-MeV proton beam and a high-resolution, 1.5-m-long focal plane detector. As a result of this experiment 27 excited ...

We introduce an iterative importance truncation scheme that aims at reducing the dimension of the model space of configuration interaction approaches by an a priori selection of the physically most relevant basis states. Using an importance measure derived from multiconfigurational perturbation theo...

We exploit a model describing the breakup of weakly bound nuclei that can be used as a laboratory for testing different prescriptions that have been advanced in the literature to take into account the nearby presence of continuum states. In the model, we follow the evolution of a single-particle wav...

The longitudinal momentum distributions of the cross sections of heavy projectile-like residues after fast, direct two-like-nucleon knockout reactions are discussed. Both the two-nucleon inelastic breakup (stripping) and the stripping-diffraction removal events are considered. We show that, because ...

Characteristic signatures of statistical Coulomb fragmentation of highly excited nuclear systems are analyzed. It is found that in many important aspects, they coincide with perceived signatures of phase transitions in confined hypothetical pseudomicrocanonical systems and, therefore, may give rise ...

The elastic scattering of the halo nucleus ⁶He from heavy targets at incident energies near the Coulomb barrier displays a marked deviation from the standard Fresnel-type diffraction behavior. This deviation is due to the strong Coulomb dipole breakup coupling produced by the Coulomb field of the he...

Fusion data for ⁴⁸Ca+⁹⁶Zr are analyzed by coupled-channels calculations. Puzzling features of a previous analysis are eliminated by applying a potential that has a shallow pocket in the entrance channel. Thus the observed S factor for fusion, which develops a maximum at low energy, can be reproduced...

High transverse momentum (P_T) γ-hadron correlations are currently being regarded as the “golden channel” for the study of the medium produced in ultrarelativistic heavy-ion collisions by means of hard probes. This is for several reasons, all linked to the fact that because of the smallness of t...

The nuclear modification factor R_AA of nonphotonic electrons in Au+Au collisions at sqrt[s_NN] =200 GeV is studied by considering the decays of heavy-flavor hadrons produced in a quark coalescence model. Although an enhanced Λ_c/D⁰ ratio is predicted by the coalescence model, it is peaked at small tr...

Anisotropic transverse flow patterns that are observed in relativistic heavy ion collisions can be added to the available microscopic Monte Carlo event generators as a final state modification to the azimuthal angles of the particles, which are generated isotropically. The method proposed for this p...

We present a microscopic calculation of the ⁶He β-decay into the ground state of ⁶Li. To this end, we use chiral perturbation theory at next-to-next-to-next-to-leading order to describe the nuclear weak-currents. The nuclear wave functions are derived from the J-matrix inverse scattering nucleon-...

The stellar (n,γ) cross section of ⁴⁰Ca at kT=25 keV has been measured with a combination of the activation technique and accelerator mass spectrometry (AMS). This combination is required when direct off-line counting of the produced activity is compromised by the long half-life and/or missing γ-r...

The cross sections of the ³He(α,α)³He and ³He(α,γ)⁷Be reactions are studied at low energies using a simple two-body model in combination with a double-folding potential. At very low energies the capture cross section is dominated by direct s-wave capture. However, at energies of several MeV the ...

Using molecular dynamics simulations, we determine the structure of neutron star crust made of rapid proton capture nucleosynthesis material. We find a regular body-centered cubic lattice, even with the large number of impurities that are present. Low-charge-Z impurities tend to occupy interstitial ...

Modern experiments with heavy ion-leptons collisions open the possibility to measure the deviation of a cross section of small angles electron(positron)-ion elastic scattering from the Rutherford formula due to multiple virtual photons exchange. The charge asymmetry and the polarization of the scatt...

We investigate the connection between the Breit and infinite momentum frames and show that when the nucleon matrix element of the time component of the electromagnetic current, which yields G_E in the Breit frame, is boosted to the infinite momentum (or light-front) frame, the quantity F₁ is obtained...

Nonmesonic decay of kaonic nuclei is investigated under a Λ(1405) doorway picture in which the K̅ absorptions in nuclei take place through the Λ(1405) resonance. Calculating Λ(1405)N→YN transitions with one-meson exchange, we find that the nonmesonic decay ratio Γ_ΛN/Γ_Σ⁰N depends s...

The polarization charges in 44,46,48Ti are studied by the microscopic particle-vibration model and used to investigate the electric quadrupole transitions of the yrast terminating bands. The validity of the common used empirical effective charges in the pf shell model calculations is confirmed. The B(E2,I I-2) and electromagnetic moments are reasonably well reproduced comparing with experimental results. It is found that the globally decreasing B(E2) is accompanied with convergence of valence particles into 1f7/2 shell when approaching the terminating states. The I=6+ state in 48Ti shows an exotic behavior with irregularity of B(E2) and sign change of electromagnetic moments, which is related to neutron dominant prolate shape.

Patterns of shape-phase transition in the proton-neutron coupled systems are studied within the SD-pair shell model. The results show that some transitional patterns in the SD-pair shell model are similar to the U(5)-SU(3), U(5)-SO(6) transitions with signatures of the critical point symmetry of the interacting boson model.

Two-nucleon separation energies are differences of binding energies. They provide important information on the relative stability of nuclei and, in particular, on shell gaps. In this work, the behaviour of the decrements (change of slope) of two-nucleon separation energies has been studied. It has been shown that the bulk of this decrement at a shell-gap consists mainly of twice the difference of two effective single particle energies, plus a pairing correction. The decrement of the two-nucleon separation energies has a maximum (spike) for N=Z nuclei. A comparison with values calculated by using a seniority binding energy formula shows that the spike is due to the Wigner energy. The evolution with nuclear mass of the isospin dependence of the Wigner energy is discussed.

We investigate the a-decay half-lives of the exotic N=125, 126,127 isotones by the generalized density-dependent cluster model (GDDCM) in combination with the microscopic two-level model. The decay widths are calculated using the overlap integral of the quasi-bound state wave function, the scattering state wave function, as well as the difference of potentials, instead of using the simple semiclassical WKB method along with the Bohr-Sommerfeld quantization condition. The a-preformation factors are evaluated by the Z-dependent formula based on the two-level model, where the closed shell effect is included. The calculated half-lives of a transitions to both ground states and excited states are found to be in good agreement with the experimental data.

We study the one-neutron removal strength of the 7He ground state, which provides us with the 6He-n component in 7He. The He isotopes are described base on the 4He+Xn cluster model (X=1,2,3). The complex scaling method is applied to describe not only the Gamow resonances but also the non-resonant continuum states of valence neutrons, with the correct boundary condition of particle decays. The one-neutron removal strength of 7He into the unbound states of 6He is calculated using the complex-scaled Green's function, in which a complex-scaled complete set of the 4He+n+n states is adopted. Using this framework, we investigate resonant and non-resonant contributions of the strength, which individually produce specific structures in the distributions. In addition, we can propose the method to obtain the real-value strength using the complex values of spectroscopic factors of Gamow states. As a result, the 6He(2+) resonance is found to give the largest contribution.

The 64Zn(t,3He) reaction has been studied by using a secondary triton beam of 115 MeV/nucleon to extract the Gamow-Teller transition-strength distribution to 64Cu. The results were compared with shell-model calculations with the pf-shell effective interactions KB3G and GXPF1A and with existing data from the 64Zn(d,2He) reaction. Whereas the experimental results exhibited good consistency, neither of the theoretical predictions managed to reproduce the data. The implications for electron-capture rates during late stellar evolution were investigated. The rates based on the theoretical strength distributions are lower by factors of 3.5-5 compared to the rates based on experimental strength distributions.

An experiment of a 29S beam bombarding on a 197Au target at an energy of 49.2 MeV/u has been performed to study the two-proton correlated emission from 29S excited states. Complete-kinematics measurements were carried out in the experiment. The relative momentum, opening angle, and relative energy of two protons, as well as the invariant mass of final system were deduced by the relativistic-kinematics reconstruction. The 27Si-p-p coincident events were picked out under strict conditions and the phenomenon of p-p correlations were observed among these events. The mechanisms of two-proton emission were analyzed in a simple schematic model, in which the extreme decay modes like 2He cluster emission, three-body phase-space decay and two-body sequential emission were taken in to account. Associated with the Monte Carlo simulations, the present results show that two-proton emitted from the excited states between 9.6 MeV and 10.4 MeV exhibits the features of 2He cluster decay with the branching ratio of 29+10-11%.

Elastic and inelastic scattering of 240 MeV sup 6 Li particles from sup 24 Mg and sup 28 Si were measured with the MDM spectrometer. Optical potential parameters for sup 6 Li + sup 24 Mg and sup 6 Li + sup 28 Si scattering systems were obtained by fitting elastic scattering with two different folding model potentials as well as W-S potentials. E0-E3 giant resonance strength distributions for sup 28 Si and sup 24 Mg were obtained. E0 strength corresponding to 34 24 106 sup + 34 sub -24 of the EWSR was identified in sup 24 Mg and 35 20 80+sup +35 sub -20% was found for sup 28 Si between Ex = 8.0 to 40.0 MeV.

The electric dipole excitation of various nuclei is calculated with a Random Phase Approximation phenomenological approach. The evolution of the strength distribution in various groups of isotopes, oxygen, calcium, zirconium and tin, is studied. The neutron excess produces E1 strength in the low energy region. Indexes to measure the collectivity of the excitation are defined. We studied the behavior of proton and neutron transition densities to determine the isoscalar or isovector nature of the excitation. We observed that in medium-heavy nuclei the low-energy E1 excitation has characteristics rather different that those exhibited by the giant dipole resonance. This new type of excitation can be identified as pygmy dipole resonance.

The multipole mixing ratios of DI=1 transitions between levels in rotational bands built on single particle states in odd neutron nuclei are dependent on the configurations of the states. In particular, the mixing ratio can be used to distinguish between several possible single particle configurations if interpreted with the particle-axial-rotor model. This work features the first determination of the ground state configurations of 109,111Ru. The single particle structures of the ground states of 101Zr and 103,105,107Mo as well as excited states in 103,107Mo are also investigated, with a new result found in 107Mo.

Quasi-elastic scattering measurements at large backward angle have been carried out for the 6Li + 232Th system at energies around Coulomb barrier. Barrier distribution has been obtained from the excitation function data. Coupled channel calculations using a double folding potential as the bare potential has been performed. The disagreement between data and theoretical predictions shows a large breakup effect in the quasi-elastic scattering of a weakly bound projectile on a deformed target.

The fragment production cross sections of secondary neutron-rich beams of , , and isotopes at energies of about 95 nbsp;have been measured. We compare the measured cross sections to EPAX, an empirical parameterization of fragmentation cross sections. A reasonable agreement of the experimental data and EPAX predictions suggests that EPAX parameterization used for stable beams seems to be valid for unstable neutron-rich ion beams. EPAX tends to over-estimate the yields of neutron-rich isotopes. This problem is amplified when neutron-rich radioactive beams are employed, leading to overly optimistic estimates of the production of neutron-rich isotopes.

We have analyzed the 16O+16O inelastic scattering to the single 21+ and 31- channels at the incident energies of Elab=350 MeV and 1120 MeV by the microscopic coupled-channel calculation. We have found that the strong rotational coupling among the channels of the a+12Cg.s. type cluster states plays an important role to reproduce the angular distribution of the 21+ channel for both energies. We also found that the coupling with the 02+, 21+ and 41+ channels as well as those among the shell channels has a large effect on the 31- channel cross sections at Elab=350 MeV. However, their absolute values could not be reproduced by our calculation, unless we assumed that the strengths of the 31- 02+, 21+, 41+ transitions were unphysically strong.

Inclusive nucleon spectra from deuteron breakup reactions on 7Li are analyzed in terms of the continuum discretized coupled channels theory for elastic breakup process and the Glauber model for nucleon stripping process. Both theoretical models use the same phenomenological nucleon optical potential of 7Li and have no other free parameters. The calculations reproduce well a prominent bump observed around half the incident energy in experimental inclusive spectra of 40 MeV (d,xn) and 100 MeV (d,xp) reactions at forward angles. The analysis shows that the stripping process is more important than the elastic breakup process in deuteron breakup reactions on 7Li.

The cross sections for formation of 92Nbm in 93Nb(n,2n)92Nbm reaction induced by 9 to 24MeV neutrons have been theoretically estimated using Talys-1.0 computer program. The variations of the cross sections with the level densities and effective imaginary potential were also studied to obtain the best fit of excitation function. It is observed that the theoretical cross sections match fairly well with the experimental cross sections reported in literature only when both contributions from negative and positive parity levels of 92Nb are considered. The results of the present study reveal that the approach of the earlier worker to neglect the contributions of the low lying negative parity energy levels in the formation of 92Nbm, in order to match the theoretical cross sections with the experimental cross sections cannot be an obvious solution, particularly when the gamma rays emitted by 92Nb nuclei in the transition from negative parity levels have been measured.

Break-up fragmentation patterns together with kinetic and configurational energy fluctuations are investigated in the framework of a microcanonical model with fragment degrees of freedom over a broad excitation energy range. As far as fragment partitioning is approximately preserved, energy fluctuations are found to be rather insensitive to both the way in which the freeze-out volume is constrained and the trajectory followed by the system in the excitation energy - freeze-out volume space. Due to hard-core repulsion, the freeze-out volume is found to be populated un-uniformly, its highly depleted core giving the source a bubble-like structure. The most probable localization of the largest fragments in the freeze-out volume may be inferred experimentally from their kinematic properties, largely dictated by Coulomb repulsion.

Recently the NA60 collaboration has reported the transverse mass spectra of dimuons coming from In-In collisions at 158 GeV/A. The measured yields display a strong invariant mass dependence not typical of radial flow, suggesting that different sources contribute in different mass regions. We interpret the dimuon transverse mass spectra from an early thermalized partonic phase and hadronic phase constrained by the strictures of broken chiral symmetry. Each phase develops a specific transverse momentum dependence by hydrodynamical expansion. We show that a measurement of the momentum anisotropy at NA60 could provide information on the dominant emission source (hadronic or partonic) in the intermediate mass region 1.5 M 3.0 GeV.

Much effort has been invested on effective-field-theoretical studies of the near-threshold NNNNp reactions and, in order to deal with the somewhat large three-momentum transfers involved, the momentum counting scheme (MCS) was proposed as an alternative to the usual Weinberg counting scheme. Given the fact that a quantitative explanation of the existing high-precision NN NNp data requires a careful examination of higher chiral order contributions to the transition operator, we make a detailed numerical investigation of the convergence property of MCS for a pilot case of the pp ppp0 reaction. Our study indicates that MCS is superior to the Weinberg scheme in identifying dominant higher order contributions to the NN NNp reactions.

The response of the QCD vacuum to very large static external magnetic fields (q B >> LQCD2) is studied. In this regime, the magnetization of the QCD vacuum is naturally described via perturbative QCD. Combining pQCD and the Schwinger proper time formalism, we calculate the magnetization of the QCD vacuum due to a strong magnetic field at leading order (one-loop) to be proportional to B logB. We show that the leading perturbative correction (two-loop) vanishes.

We present an equation of state and composition of low-density supernova matter composed of light nuclei with mass number A 13. We work within the quasiparticle gas model, which accounts for bound states with decay timescales larger than the relevant timescale of supernova and protoneutron star evolution. The mean-field contribution is included in terms of Skyrme density functional. Deuterons, tritons, and 3H(e) nuclei appear in matter in concentrations that are substantially higher than those of heavier nuclei. We calculate the critical temperature of deuteron condensation in such matter, and demonstrate that the appearance of clusters substantially lowers the critical temperature.

In astrophysical environments, the long-lived (T1/2 = 37.6 Gy) ground state of nbsp;can communicate with a short-lived (T1/2 = 3.664 h) isomeric level through thermal excitations. Thus, the lifetime of nbsp;in an astrophysical environment can be quite different than in the laboratory. We examine the possibility that the rate of equilibration can be enhanced via K-mixing of two levels near keV and estimate the relevant g-decay rates. We use this result to illustrate the effect of K-mixing on the effective stellar half-life. We also present a network calculation that includes the equilibrating transitions allowed by K-mixing. Even a small amount of K-mixing will decrease the timescale for equilibration during an nbsp;triggered by the nbsp;neutron source.

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