Direct experimental evidence for strong admixture of different parity states in "1"1Li

Peripheral fragmentation of a 287 MeV/u beam of the halo nucleus "1"1Li incident on a carbon target has been studied in a fragment-neutron coincidence experiment. The momentum distribution of the "1"0Li fragments gives access to the momentum distribution of the removed neutron in "1"1Li. From the shape of the distribution, the (1s_1_/_2)"2 contribution to the mixture of (1s_1_/_2)"2 and (0p_1_/_2)"2 components in the ground-state wave function was determined to be 45#+-#10%. The angular correlation between the knocked out neutron and the one from the decay of "1"0Li shows a skew distribution signalling interference of these two different parity states. (orig.)22 refs.Available from TIB Hannover: RO 801(99-22) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

A large area scintillating fiber detector for relativistic heavy ions

A scintillating fiber detector for relativistic heavy ions with an active area of 50 x 50 cm"2 has been developed and was tested with various ion beams (1#<=#Z#<=#92). A count rates of up to 10"5 particles/s, the position resolution was found to be determined by the fiber width of 1 mm; depending on the nuclear charge of the beam, efficiencies between 89% and 100% and time resolutions between 800 and 200 ps (FWHM) were obtained. (orig.)SIGLEAvailable from TIB Hannover: RO 801(97-60) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Large electron polarization of H-like "2"0Ne-ions traversing Gd foils at very high velocities

Copy held by FIZ Karlsruhe; available from UB/TIB Hannover / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Invariant mass spectrum and #alpha# - n correlation function studied in the fragmentation of "6He on a carbon target

Momentum distributions and invariant mass spectra from the breakup of "6He ions with an energy of 250 MeV/u interacting with a carbon target have been studied. The data were used to extract information about the reaction mechanism which is influenced by the structure of "6He. It is found that the dominant reaction mechanism is a two-step process: knock out of one neutron followed by the decay of the "5He resonance. The shape of the (#alpha#+n) two-body invariant mass spectrum is interpreted as mainly reflecting the "5He ground state which is a J "#pi# =3/2"- resonance. However, no evidence for correlations between #alpha# particles and neutrons is observed in the momentum widths of the distributions. It is demonstrated that a combined analysis of the two-body invariant mass spectrum and an appropriate correlation function may be used to determine the properties of the intermediate resonance. (orig.)Available from TIB Hannover: RO 801(97-61) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Invariant-mass spectroscopy of "1"0Li and "1"1Li

Break-up of secondary "1"1Li ion beams (280 MeV/nucleon) on C and Pb targets into "9Li and neutrons is studied experimentally. Cross sections and neutron multiplicity distributions are obtained, characterizing different reaction mechanisms. Invariant-mass spectroscopy for "1"1Li and "1"0Li is performed. The E1 strength distribution, deduced from electromagnetic excitation of "1"1Li up to an excitation energy of 4 MeV comprises #approx#8% of the Thomas-Reiche-Kuhn energy-weighted sum-rule strength. Two low-lying resonance-like structures are observed for "1"0Li at decay energies of 0.21(5) and 0.62(10) MeV, the former one carrying 26(10)% of the strength and likely to be associated with an s-wave neutron decay. A strong di-neutron correlation in "1"1Li can be discarded. Calculations in a quasi-particle RPA approach are compared with the experimental results for "1"0Li and "1"1Li. (orig.)SIGLEAvailable from TIB Hannover: RO 801(97-14) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Neutron momentum distribution from ''core break-up'' reactions of halo nuclei

Neutron angular distributions from violent break-up reactions of "1"1Li and "1"1Be have been measured at 28 MeV/u and 280 MeV/u and at 41 MeV/u and 460 MeV/u, respectively. The derived neutron momentum distributions show a narrow component in transverse momentum that is within uncertainties independent of beam energy and target charge. This component is suggested to be simply related to the momentum distribution of the loosely bound halo neutron(s) in the projectiles. (orig.)SIGLEAvailable from TIB Hannover: RO 801(95-02) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

"6He and neutron momentum distributions from "8He in nuclear break-up reactions at 240 MeV/u

Neutron and "6He momentum distributions from "8He break-up reactions in a C-target have been measured at 240 MeV/u. The two-neutron removal cross section was found to be #sigma#_-_2_n=0.27#+-#0.03 b. The nature of the momentum distributions is interpreted in some simple reaction scenarios. (orig.)32 refs.SIGLEAvailable from TIB Hannover: RO 801(96-04) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman