Neutron and Gamma Decays of Giant Resonances in 2°8Pb Excited by 381 MeV 17O Ions PDF Download
Are you looking for read ebook online? Search for your book and save it on your Kindle device, PC, phones or tablets. Download Neutron and Gamma Decays of Giant Resonances in 2°8Pb Excited by 381 MeV 17O Ions PDF full book. Access full book title Neutron and Gamma Decays of Giant Resonances in 2°8Pb Excited by 381 MeV 17O Ions by . Download full books in PDF and EPUB format.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :
Get Book Here
Book Description
Coincidence experiments designed to study the decay of giant resonances (GR) can, in principle, provide information on the microscopic structure of the giant resonance region to supplement the large body of singles inelastic electron and hadron scattering data which has been acquired over the last decade. Furthermore, such coincidence experiments can benefit from the large cross sections for excitation of the isoscalar GR by inelastic scattering of heavy ions without suffering from problems which appear to limit the usefulness of heavy ions in singles experiments. This paper is a preliminary report on the use of the ORNL Spin Spectrometer, a 4.pi., segmented NaI gamma ray spectrometer to study the neutron and gamma decay of the GR region (E* approx. 9-20 MeV) in 2°8Pb. Results are presented and discussed. (WHK).
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :
Get Book Here
Book Description
Coincidence experiments designed to study the decay of giant resonances (GR) can, in principle, provide information on the microscopic structure of the giant resonance region to supplement the large body of singles inelastic electron and hadron scattering data which has been acquired over the last decade. Furthermore, such coincidence experiments can benefit from the large cross sections for excitation of the isoscalar GR by inelastic scattering of heavy ions without suffering from problems which appear to limit the usefulness of heavy ions in singles experiments. This paper is a preliminary report on the use of the ORNL Spin Spectrometer, a 4.pi., segmented NaI gamma ray spectrometer to study the neutron and gamma decay of the GR region (E* approx. 9-20 MeV) in 2°8Pb. Results are presented and discussed. (WHK).
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :
Get Book Here
Book Description
Experiments on 2°8Pb bombarded by 17O at 22 MeV/nucleon (ORNL) and 84 MeV nucleon (GANIL) are reviewed. Inelastically scattered projectiles were detected at forward angles in coincidence with gamma rays seen in NaI (ORNL) or in BaF2 (GANIL). The 17O were identified by 6 Si telescopes covering THETA = 11. 5/degree/--14.5/degree/ (ORNL) or by the focal-plane detector system of the energy-loss spectrometer SPEG, set to accept THETA = 1. 5/degree/--5.0/degree/ (GANIL). The .gamma.-ray data provide information on the multipole character of various parts of the giant resonance region, matrix elements between the GR region and low-lying states in 2°8Pb, and the relative contribution of direct and compound process to .gamma.0 decay. At the higher energy the 9--15 MeV GR region is excited very strongly. The isovector giant dipole is dominant over most of the angles studied. Significant contributions from the isoscalar giant quadrupole and monopole resonances are also present. Decomposition of the GR into L = 1, 2, and 0 components was based on coincidences with the overwhelmingly dipole .gamma.0 transitions. The magnitude (1.7 +- 0.2%) and energy distribution of the .gamma.0 branch can be reproduced well by a parameter-free calculation. The .gamma.0 decay of the isoscalar giant quadrupole resonance is more easily observed at the lower energy. The .gamma.0 angular correlations confirm the presence of E2 radiation from states in the 9--11 MeV region. The B(E2) implies that the ratio of neutron to proton matrix elements is consistent with the expected value of N/Z. This conclusion is confirmed by evidence form Coulomb-nuclear interference in the singles data at 84 MeV/nucleon. Photon decays to excited states indicate that 4 and/or 6/sup +/ strength is present around 9--10 MeV, and are consistent with a monopole contribution from 12.5--15.5 MeV. 20 refs., 14 figs.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :
Get Book Here
Book Description
The neutron decay of the giant multipole resonance region between 9 to 15 MeV in 2°8Pb has been studied. The giant resonances were excited by inelastic scattering of 17O at 380 MeV. Neutrons from 2°8Pb and .gamma. rays from 2°7Pb were detected in the ORNL Spin Spectrometer and the 17O in .delta. E-E silicon detector telescopes. The neutron branching ratios for the decay to the ground state and to the low lying excited states of 2°7Pb were measured as a function of the excitation energy of 2°8Pb and compared to Hauser-Feshbach calculations. Evidence for non statistical neutron decay to selected single-hole states, and to hole-surface vibration and hole-pairing vibration coupled states was found. 18 refs., 1 tab., 5 figs.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :
Get Book Here
Book Description
Results from studies of gamma decay of giant resonances in 2°8Pb and 9°Zr following inelastic excitation by 22 and 84 MeV/nucleon 17O ions are presented. Data on ground state decay of isoscalar giant quadrupole and isovector giant dipole resonances are presented and compared with calculations. Decays from resonances to low lying excited states are also discussed. Preliminary results from an attempt to isolate the isovector quadrupole resonance in 2°8Pb using its gamma decay are presented.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :
Get Book Here
Book Description
Inelastic scattering of medium energy heavy ions provides very large cross sections and peak-to-continuum ratios for excitation of giant resonances. For energies above about 50 MeV/nucleon, giant resonances are excited primarily through Coulomb excitation, which is indifferent to isospin, thus providing a good probe for the study of isovector giant resonances. The extremely large cross sections available from heavy ion excitation permit the study of rare decay modes of the giant resonances. In particular, recent measurements have been made of the photon decay of giant resonances following excitation by 22 and 84 MeV/nucleon 17O projectiles. The singles results at 84 MeV/nucleon yield peak cross sections for the isoscalar giant quadrupole resonance and the isovector giant dipole resonance of approximately 0.8 and 3 barns/sr, respectively. Data on the ground state decay of the isoscalar giant quadrupole and isovector giant dipole resonances are presented and compared with calculations. Decays to low-lying excited states are also discussed. Preliminary results from an experiment to isolate the 2°8Pb isovector quadrupole resonance using its gamma decay are presented. 22 refs., 19 figs., 1 tab.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :
Get Book Here
Book Description
Inelastic scattering of medium energy heavy ions provides very large cross sections and peak-to-continuum ratios for excitation of giant resonances. For energies above about 50 MeV/nucleon, giant resonances are excited primarily through Coulomb excitation, which is indifferent to isospin, thus providing a good probe for the study of isovector giant resonances. The extremely large cross sections available from heavy ion excitation permit the study of rare decay modes of the photon decay of giant resonances following excitation by 22 and 84 MeV/nucleon 17O projectiles. The singles results at 84 MeV/nucleon yield peak cross sections for the isoscalar giant quadrupole resonance and the isovector giant dipole resonance of approximately 0.8 and 3 barns/sr, respectively. Data on the ground state decay of the isoscalar giant quadrupole and isovector giant dipole resonances are presented and compared with calculations. Decays to low-lying excited states are also discussed. Preliminary results from an experiment to isolate the 2°8Pb isovector quadrupole resonance using its gamma decay are presented.
Author: J. J. (Niels Bohr Institutet) Gaardhøje
Publisher:
ISBN:
Category :
Languages : en
Pages :
Get Book Here
Book Description
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :
Get Book Here
Book Description
The role of intermediate energy heavy ions in the study of giant multipole resonances is explored, with emphasis on gamma decay coincidence experiments. Experiments on 2°8Pb bombarded by 22 MeV/nucleon and 84 MeV/nucleon 17O are discussed and compared. The role of Coulomb excitation in the 84 MeV/nucleon data is emphasized and some consequences for study of isovector resonance strength are explored. A comparison of the excitation and decay of the isovector giant dipole resonance in 2°8Pb and 2°9Bi excited with 84 MeV/nucleon 17O scattering is presented. 19 refs., 15 figs., 1 tab.
