Coulomb excitation of exotic nuclei and segmented germanium detectors
- Department of Physics and Astronomy and National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, Michigan 48824 (United States)
The experimental technique of intermediate-energy Coulomb excitation allows for in-beam {gamma}-ray spectroscopy of {beta}-unstable nuclei far from stability. The large velocity ({nu}/c{approx_equal}0.25-0.6) of radioactive beams prepared by in-flight separation techniques allows the use of thick secondary targets (100-1000 mg/cm{sup 2}) and measurements can be performed in a few days with beam rates as low as 10 particles/s. In a single experiment one can simultaneously measure the energy of excited bound states with respect to the ground state in exotic nuclei as well as the Coulomb excitation cross section to excite these states. This cross section is a direct function of the electromagnetic matrix elements B(E{lambda}) and B(M{lambda}) and can be used--together with the measured excitation energies--to study experimentally the evolution of nuclear shells far from stability. Since inelastic scattering to a bound state is indicated through the presence of a photon, which is emitted from the moving projectile, the large Doppler shift of the detected photon energy requires the use of position-sensitive photon detectors. Until now, photon detectors used in intermediate-energy Coulomb excitation experiments were primarily based on scintillation detectors. This limited the achievable energy resolution to about {delta}E/E=6%. With the advent of highly-segmented large-volume germanium detectors it will be possible within the next year to perform in-beam {gamma}-ray spectroscopy experiments with fast exotic beams and to achieve energy resolutions comparable to the intrinsic energy resolution of germanium detectors ({delta}E/E=0.2%). Segmented germanium detector arrays, including the one under construction at the NSCL, are described and their possible applications at present and future radioactive ion-beam facilities will be discussed.
- OSTI ID:
- 21207736
- Journal Information:
- AIP Conference Proceedings, Vol. 455, Issue 1; Conference: ENAM 98: 2. international conference on exotic nuclei and atomic masses, Bellaire, MI (United States), 23-27 Jun 1998; Other Information: DOI: 10.1063/1.57319; (c) 1998 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0094-243X
- Country of Publication:
- United States
- Language:
- English
Similar Records
Future Gamma-Detector Arrays for Radioactive Beam Applications
Precision lifetime measurements of exotic nuclei based on Doppler-shift techniques