Isoscalar Giant Resonance Research Articles

Isoscalar Giant Resonances of 120Sn in the QuasiparticleRelativistic Random Phase Approximation

The quasiparticle relativistic random phase approximation (QRRPA)is formulated based on the relativistic mean field ground state inthe response function formalism. The pairing correlations aretaken into account in the Bardeen–Cooper–Schrieffer approximation with aconstant pairing gap. The numerical calculations are performed in thecase of various isoscalar giant resonances of nucleus 120Sn withparameter set NL3. The calculated results show that the QRRPAapproach could satisfactorily reproduce the experimental data ofthe energies of low-lying states.

Shape fluctuations in a Fermi system with nonlinear dissipativity

The contribution of thermal fluctuations to the widths of isoscalar giant multipole resonances (GMR) in heated nuclei is studied. Starting from the collisional kinetic equation, it is shown that an additional contribution to the nuclear friction and the corresponding GMR widths arises due to the nonlinear dissipativity effect. It is also shown that the magnitude of the contributions of the thermal fluctuations to the nuclear friction coefficient and the GMR widths do not exceed 20%.

The effect of deformation in the isoscalar giant dipole resonance

Background-free inelastic scattering spectra have been obtained for144,148,150,152,154Sm with 386 MeV α particles at forward angles (including 0°) to investigate the effect of deformation on the isoscalar giant dipole resonance. The strength distributions for isoscalar giant resonances have been extracted via a multipole decomposition analysis using angular distributions calculated in the framework of the density-dependent single-folding model. The effects of deformation are found to be different for the low- and high-excitation energy components of the isoscalar giant dipole resonance. Evidence has been obtained for the theoretically-predicted mixing between the isoscalar giant dipole resonance and the high energy octupole resonance.

The effect of deformation in the isoscalar giant dipole resonance

Background-free inelastic scattering spectra have been obtained for 144,148,150,152,154 Sm with 386 MeV α particles at forward angles (including 0°) to investigate the effect of deformation on the isoscalar giant dipole resonance. The strength distributions for isoscalar giant resonances have been extracted via a multipole decomposition analysis using angular distributions calculated in the framework of the density-dependent single-folding model. The effects of deformation are found to be different for the low- and high-excitation energy components of the isoscalar giant dipole resonance. Evidence has been obtained for the theoretically-predicted mixing between the isoscalar giant dipole resonance and the high energy octupole resonance.

Isoscalar giant dipole resonance for several nuclei with A ≥ 90

The giant resonance region in several nuclei in A ≥ 90 have been re-measured using 240 MeV α particle scattering with a detector provides that both horizontal and vertical angles. Slice analyses with multipole fits were performed and strength due to both low and high energy components of the isoscalar giant dipole resonance (ISGDR) was identified. E1 strengths for the high energy component corresponding to 70±15%,68±15% and 67±14% of the isoscalar E1 energy-weighted sum rule were identified, with centroid energies of 26.3±0.6 MeV, 24.7±0.6 MeV and 21.7±0.6 MeV for90Zr,144Sm and208Pb, respectively. The centroid of the high energy component of the strength distribution is in closer agreement with the microscopic prediction generated using compressibilities obtained from the isoscalar giant monopole resonance data.

The isoscalar giant dipole resonance: A status report

The current status of the experimental work on the Isoscalar Giant Dipole Resonance (ISGDR) is reviewed. Results are presented from recent measurements at RCNP, Osaka, using small-angle inelastic scattering of 400 MeV α particles, and the implications of these results on the determination of nuclear incompressibility are discussed.

Theoretical understanding of the nuclear incompressibility: where do we stand?

The status of the theoretical research on the compressional modes of finite nuclei and the incompressibility K ∞ of nuclear matter, is reviewed. It is argued that the recent experimental data on the Isoscalar Giant Monopole Resonance (ISGMR) allow extracting the value of K ∞ with an uncertainity of about ± 12 MeV. Non-relativistic (Skyrme, Goguy) and relativistic mean field models predict for K ∞ values which are significantly different from one another, namely ≈ 220–235 and 250–270 MeV respectively. It is shown that the solution of this puzzle requires a better determination of the symmetry energy at, and around, saturation. The role played by the experimental data of the Isoscalar Giant Dipole Resonance (ISGDR) is also discussed.

Theoretical understanding of the nuclear incompressibility: where do we stand?

The status of the theoretical research on the compressional modes of finite nuclei and the incompressibility K ∞ of nuclear matter, is reviewed. It is argued that the recent experimental data on the Isoscalar Giant Monopole Resonance (ISGMR) allow extracting the value of K ∞ with an uncertainity of about ± 12 MeV. Non-relativistic (Skyrme, Goguy) and relativistic mean field models predict for K ∞ values which are significantly different from one another, namely ≈ 220–235 and 250–270 MeV respectively. It is shown that the solution of this puzzle requires a better determination of the symmetry energy at, and around, saturation. The role played by the experimental data of the Isoscalar Giant Dipole Resonance (ISGDR) is also discussed.

The isoscalar giant dipole resonance: A status report

The current status of the experimental work on the Isoscalar Giant Dipole Resonance (ISGDR) is reviewed. Results are presented from recent measurements at RCNP, Osaka, using small-angle inelastic scattering of 400 MeV α particles, and the implications of these results on the determination of nuclear incompressibility are discussed.

Particle decay of the isoscalar giant dipole resonance inPb

The direct particle decay of the isoscalar giant dipole resonance (ISGDR) has been studied in208Pb using the (α, α′p) and (α, α′n) reactions at a bombarding energy of 200 MeV. The direct-decay channels of proton and neutron emissions were observed in coincidence with the scattered α-particles in order to study the population of proton-hole states in207T1 and neutron-hole states in207Pb. The results of the partial and total branching ratios allowed us to test recently performed continuum-RPA (CRPA) calculations for the ISGDR and thereby to learn about its microscopic structure.

Isoscalar giant dipole resonance for several nuclei with A ≥ 90

Isoscalar giant dipole resonance for several nuclei with A ≥ 90

Particle decay of the isoscalar giant dipole resonance inPb

The direct particle decay of the isoscalar giant dipole resonance (ISGDR) has been studied in208Pb using the (α, α′p) and (α, α′n) reactions at a bombarding energy of 200 MeV. The direct-decay channels of proton and neutron emissions were observed in coincidence with the scattered α-particles in order to study the population of proton-hole states in207T1 and neutron-hole states in207Pb. The results of the partial and total branching ratios allowed us to test recently performed continuum-RPA (CRPA) calculations for the ISGDR and thereby to learn about its microscopic structure.

The effect of deformation in the isoscalar giant dipole resonance

Background-free inelastic scattering spectra have been obtained for 144,148,150,152,154Sm with 386 MeV α particles at forward angles (including 0°) to investigate the effect of deformation on the isoscalar giant dipole resonance. The strength distributions for isoscalar giant resonances have been extracted via a multipole decomposition analysis using angular distributions calculated in the framework of the density-dependent single-folding model. The effects of deformation are found to be different for the low- and high-excitation energy components of the isoscalar giant dipole resonance. Evidence has been obtained for the theoretically-predicted mixing between the isoscalar giant dipole resonance and the high energy octupole resonance.

Isoscalar giant dipole resonance for several nuclei with A ≥ 90

The giant resonance region in several nuclei in A ≥ 90 have been re-measured using 240 MeV α particle scattering with a detector provides that both horizontal and vertical angles. Slice analyses with multipole fits were performed and strength due to both low and high energy components of the isoscalar giant dipole resonance (ISGDR) was identified. E1 strengths for the high energy component corresponding to 70±15%,68±15% and 67±14% of the isoscalar E1 energy-weighted sum rule were identified, with centroid energies of 26.3±0.6 MeV, 24.7±0.6 MeV and 21.7±0.6 MeV for 90Zr, 144Sm and 208Pb, respectively. The centroid of the high energy component of the strength distribution is in closer agreement with the microscopic prediction generated using compressibilities obtained from the isoscalar giant monopole resonance data.

Theoretical understanding of the nuclear incompressibility: where do we stand?

The status of the theoretical research on the compressional modes of finite nuclei and the incompressibility K ∞ of nuclear matter, is reviewed. It is argued that the recent experimental data on the Isoscalar Giant Monopole Resonance (ISGMR) allow extracting the value of K ∞ with an uncertainity of about ± 12 MeV. Non-relativistic (Skyrme, Goguy) and relativistic mean field models predict for K ∞ values which are significantly different from one another, namely ≈ 220–235 and 250–270 MeV respectively. It is shown that the solution of this puzzle requires a better determination of the symmetry energy at, and around, saturation. The role played by the experimental data of the Isoscalar Giant Dipole Resonance (ISGDR) is also discussed.

The isoscalar giant dipole resonance: A status report

The current status of the experimental work on the Isoscalar Giant Dipole Resonance (ISGDR) is reviewed. Results are presented from recent measurements at RCNP, Osaka, using small-angle inelastic scattering of 400 MeV α particles, and the implications of these results on the determination of nuclear incompressibility are discussed.

Particle decay of the isoscalar giant dipole resonance in 208Pb

The direct particle decay of the isoscalar giant dipole resonance (ISGDR) has been studied in 208Pb using the (α, α′ p) and (α, α′ n) reactions at a bombarding energy of 200 MeV. The direct-decay channels of proton and neutron emissions were observed in coincidence with the scattered α-particles in order to study the population of proton-hole states in 207T1 and neutron-hole states in 207Pb. The results of the partial and total branching ratios allowed us to test recently performed continuum-RPA (CRPA) calculations for the ISGDR and thereby to learn about its microscopic structure.

Systematic study ofL⩽3giant resonances in Sm isotopes via multipole decomposition analysis

Background-free inelastic scattering spectra have been obtained for five Sm isotopes with $386\text{\ensuremath{-}}\text{MeV}$ $\ensuremath{\alpha}$ particles at forward angles (including $0\ifmmode^\circ\else\textdegree\fi{}$) to investigate the effect of deformation on the compressional-mode giant resonances. The strength distributions for the $L\ensuremath{\leqslant}3$ isoscalar giant resonances have been extracted via a multipole decomposition analysis using angular distributions calculated in the framework of the density-dependent single-folding model. We observed a splitting of the giant monopole resonance because of its mixing with the giant quadrupole resonance. For the isoscalar giant dipole resonance, the observed effects of deformation are different for the low- and high-excitation-energy components. Evidence has been obtained for the theoretically predicted mixing between the isoscalar giant dipole resonance and the high energy octupole resonance.

Direct proton decay of the isoscalar giant dipole resonance

The direct proton decay of the isoscalar giant dipole resonance (ISGDR) has been studied in 208Pb using the (α,α′p) reaction at a bombarding energy of 200 MeV. Through observation of direct-decay protons from the ISGDR in coincidence with scattered α-particles, the population of proton–hole states in 207Tl was studied, allowing us to test recently performed continuum-RPA (CRPA) calculations for the ISGDR and thereby to learn about its microscopic structure. The energy and width of the ISGDR were also determined to be 22.1±0.3 MeV and 3.8±0.8 MeV, respectively. A new resonance of quadrupole character was observed at Ex=26.9±0.7 MeV with a width of 6.0±1.3 MeV.

Current status of the nuclear matter incompressibility coefficient as deduced from data on compression modes

We review the current status of the nuclear matter incompressibility coefficient, K nm , as deduced from experimental data on excitation cross sections, σ( E), for the isoscalar giant monopole resonance (ISGMR) and the isoscalar giant dipole resonance (ISGDR). We present results of microscopic calculations for the σ( E) of the ISGMR and the ISGDR, providing a resolution of the long standing problem concerning the value of K nm , deduced from the ISGDR data.