M. Ramírez

Effect of the breakup on the fusion and elastic scattering of weakly bound projectiles on {sup 64}Zn

We study the behavior of the fusion, breakup, reaction, and elastic scattering of different projectiles on {sup 64}Zn, at near and above barrier energies. We present fusion and elastic scattering data with the tightly bound {sup 16}O and the stable weakly bound {sup 6}Li, {sup 7}Li, and {sup 9}Be projectiles. The data are analyzed by coupled channel calculations. The total fusion cross sections for these systems are not affected by the breakup process at energies above the barrier. The elastic (noncapture) breakup cross section is important at energies close to and above the Coulomb barrier and increases the reaction cross sections. In addition, we show that the breakup process at near and below barrier energies is responsible for the vanishing of the usual threshold anomaly of the optical potential and gives rise to a new type of anomaly.

No evidence of break-up effects on the fusion of 9Be with medium-light nuclei

Abstract Fusion cross sections were measured for the 9 Be + 27 Al and 19 F + 9 Be , 12C systems, at energies above the Coulomb barrier, in order to investigate the possible effect of fusion hindrance due to the break-up of the weakly bound nuclei. Comparisons with one-dimensional barrier penetration models and with other similar systems, where no break-up is expected to occur, show no evidence of fusion hindrance.

Examination of nuclear measurement conditions in cold fusion experiments

The recent announcement of electrochemically induced nuclear fusion [1,2] has generated great interest and activity within the scientific community. In particular, there are several aspects related to the work of ref. 1 which are not fully understood and therefore deserve further investigation. One of them is the huge discrepancy between the amount of measured heat and the intensity of the supposedly accompanying nuclear radiation, namely neutrons and gamma rays. In view of the fact that the detection of nuclear radiation in the context of an electrochemical process is perhaps the most unequivocal fingerprint for the occurrence of fusion, we feel that a careful re-evaluation of the measurement conditions may be needed. In order to address this question, in the present paper we report on an attempt to observe this phenomenon and on the possible problems related to the detection techniques.

The AMS system and research program at the TANDAR laboratory

Abstract Several aspects of the AMS program at the TANDAR laboratory are discussed. The current activities are focused on environmental and cosmological applications. One of the projects has been the study of the global fallout of the radioisotope 36Cl and its latitudinal distribution in the southern hemisphere. We have also undertaken some of the preparatory work to measure the concentration of several radioisotopes in extraterrestrial samples obtained from a meteorite fall in northern Argentina. An important fraction of our effort in pursuing these studies has been the optimization of the technique in our 20 UD tandem. We discuss the results of recent tests carried out to evaluate the current capabilities of the accelerator regarding general stability, predictability and transmission efficiency, following the upgrading and adaptation activities.

The AMS program at the TANDAR accelerator

Abstract The accelerator mass spectrometry (AMS) program that is under development using the 20UD electrostatic accelerator TANDAR at Buenos Aires is presented. Tests and measurements in order to evaluate and to improve the accelerator performance are described. Preliminary measurements have been done by tuning 14C beams using as detection system a ΔE-ER telescope. For the detection of heavier isotopes some new developments are being currently implemented in a quadrupole-dipole-dipole (QDD) magnetic spectrometer. Furthermore, work is in progress to construct a time-of-flight system using two micro-channel plates prior to the entrance to the QDD spectrometer.

Initial tests of the magnetic spectrometer at the TANDAR accelerator

Abstract A new magnetic spectrometer has started operating at the 20 UD tandem accelerator of the TANDAR laboratory. A large acceptance angle and the ability to handle a broad range of energies and masses are its main characteristics. The associated detection system consists of a multiwire vertical drift chamber, an ionization chamber and a plastic scintillator. The complete device was tested using the scattering of 12 C, 16 O, and 32 S on 197 Au, and 16 O beams on 120 Sn. A summary of the most important features of the system and the results of the tests are presented.

Fusion cross sections for the 6,7Li+27Al, 9Be+27Al systems

We present the results of total fusion cross sections measurements for the 6,7Li + 27Al, 9Be + 27Al, systems at energies above and below the Coulomb barrier (0.8Vb ⩽ E ⩽ 2.0Vb). The experimental evidence at the measured energy regime show that the total fusion cross sections of 6Li and 9Be with a light mass target are not affected by the break‐up process. The elastic break up cross sections for the 6Li + 27Al system were also measured and the results are being presented in this issue. The data for the 7Li + 27Al system are still being analyzed and therefore these results should be considered preliminary.

Fusion cross section measurements for systems 6Li + 27Al,64Zn at near-barrier energies

Fusion cross-sections were measured for the 6Li+27 Al,64 Zn and 9Be+64Zn systems at energies around the Coulomb barrier, in order to study the influence of the break-up of weakly bound nuclei on the fusion process.