D. Bazin

Identification of the doubly-magic nucleus 100Sn in the reaction 112Sn+natNi at 63 MeV/nucleon

Abstract We report on the production of the doubly-magic nucleus 100 Sn and other proton-rich nuclei in the A ∼ 100 region in the reaction 112 Sn + nat Ni at 63 MeV/nucleon. The experiment was carried out using the high acceptance device SISSI and the Alpha and LISE3 spectrometers at GANIL. The identification of the reaction products ( A , Z and Q ) was made using the measurements of time-of-flight, energy-loss and kinetic energy.

β-Delayed neutron emission of the isotopes 20C, 40,41,42P, 43,44S☆

Abstract Very neutron-rich isotopes have been produced by the fragmentation of 55 MeV/u 48 Ca projectiles from GANIL onto a 181 Ta target. The nuclei were separated by means of the doubly achromatic spectrometer LISE and implanted into a semiconductor telescope for identification in Z and A . Their β-delayed neutron radioactivity is observed by means of a 4π β -n coincidence detector. The results include first measurements of the half-life T 1 2 and the neutron emission probability P n for the isotopes 20 C, 40,41,42 p and 43,44 S. They are compared to current theoretical predictions.

Total and 2n-removal cross sections of the neutron-rich isotopes 8,9,11Li☆

Abstract Total interaction cross sections have been measured for 8 Li on C and Pb targets, for 9 Li on C, Al, Cu, Sn and Pb targets, as well as for 11 Li on C, Sn and Pb targets at about 80 MeV/nucleon. In addition, 2n-removal cross sections for 11 Li have been extracted. These measurements are used to determine the nuclear and the electromagnetic part of the cross sections for the different projectile-target combinations. The experimental results are compared to different model calculations. These comparisons allow one to draw conclusions on the matter density distribution of the neutron-rich lithium isotope 11 Li. By comparing our data on the electromagnetic dissociation of 11 Li with all the other data available in the literature, we are able to put constraints on the dipole-strength distribution in 11 Li.

Measurement and QRPA calculation of the β-delayed neutron emission of 21,22N and 23,24O☆

Abstract Neutron-rich isotopes of nitrogen and oxygen have been produced as projectile-like fragments in the reaction of a 44 MeV/u 48 Ca beam with a 173mg/cm 2 181 Ta target. The fragments have been analyzed by the doubly achromatic spectrometer LISE and implanted in a semiconductor identification telescope, surrounded by a 4π neutron detector in order to observe their radioactive decay. The β-delayed neutron emission has been measured for the isotopes 21,22 N and 23,24 O for the first time and the β-half-lives T 1 2 and delayed neutron-emission probabilities P n are determined. These values are discussed within the framework of a QRPA calculation. The influence of the decay energy Q β used in the calculation is examined, indicating the reliability of predicted matrix elements. Furthermore, P n values are calculated and compared to the experimental data.

Identification of 100Sn and others proton drip-line nuclei in the reaction 112Sn(63 MeV/nucl.)+natNrmNi

Abstract Six new neutron-deficient nuclei 103Sb, 104Sb, 98In, 91Pd, 89Rh and 87Ru have been identified among the products of quasi-fragmentation of a 112Sn beam (63 MeV/nucl.), in addition to the previously reported 100Sn and 102Sn. Decays of over forty short-lived ( T 1 2 from ≈50 ns to 70μ s ) isomeric states including new isomer 66mAs were observed in the same reaction.

β-Delayed neutron emission of15B,18C,19,20N,34,35Al and39P

The isotopes15B,18C,19,20N,34,35Al and39P have been produced as projectile-like fragments from the interaction of a86Kr beam of 45 MeV/u from GANIL with a181Ta target. Separated by the 0° magnetic analyser LISE, the nuclei are identified by means of aΔE- E semiconductor telescope. It is surrounded, in a geometry close to 4π, by a thin plastic scintillator (NE 102) and a large volume liquid scintillator (NE 213) for the detection of betas and neutrons, respectively, from the decay of the implanted nuclei. By observation of theβ-delayed neutrons, the half-livesT1/2 and neutron emission probabilitiesPn have been measured. TheT1/2 of18C,20N,35Al,39P and Pn of18C,19,20N,34,35Al and39P are determined for the first time. For the isotopes17C,36,37Si and38P upper limits of Pn are deduced.

Production of isomeric44V and42Sc in high energy heavy ion reactions

Beta-coincidentγ-rays were measured from implanted44V and42Sc nuclei. These were selected after58Ni+nickel reactions by means of the LISE3 spectrometer at GANIL. The production of the isomeric states was identified by detecting their typicalβ-delayedγ-ray cascades. From the intensities of the detectedγ-lines the ratio between isomer and ground-state production of44V follows to be 1 to 3.0(4).

First observation of the neutron-rich nuclei42Si,45, 46P,48S, and51Cl from the interaction of 44 MeV/u48Ca +64Ni

Five new very neutron-rich isotopes,42Si,45,46P,48S and51Cl, are identified from the interaction of a 44 MeV/u48Ca beam with a64Ni target.

Particle stability of the isotopes sup 26 O and sup 32 Ne in the reaction 44 MeV/nucleon sup 48 Ca+Ta

An attempt has been made to synthesize the extremely neutron-rich isotope {sup 26}O in the nuclear reaction 44 MeV/nucleon {sup 48}Ca+Ta. Use was made of magnetic separation and identification methods including time-of-flight and {Delta}{ital E},{ital E} measurements. The {sup 26}O nucleus appears to be unstable against particle emission since no events attributable to the {sup 26}O nucleus were observed at a level one order of magnitude lower than that predicted from the extrapolated yields. The previously unobserved isotope {sup 32}Ne was found to be particle stable and the isotope {sup 31}Ne particle unstable. Neutron-separation energies calculated with different models are tabulated.

Particle stability of the isotopesO26andNe32in the reaction 44 MeV/nucleonCa48+Ta

An attempt has been made to synthesize the extremely neutron-rich isotope {sup 26}O in the nuclear reaction 44 MeV/nucleon {sup 48}Ca+Ta. Use was made of magnetic separation and identification methods including time-of-flight and {Delta}{ital E},{ital E} measurements. The {sup 26}O nucleus appears to be unstable against particle emission since no events attributable to the {sup 26}O nucleus were observed at a level one order of magnitude lower than that predicted from the extrapolated yields. The previously unobserved isotope {sup 32}Ne was found to be particle stable and the isotope {sup 31}Ne particle unstable. Neutron-separation energies calculated with different models are tabulated.