Alessandra Guglielmetti

LUNA: Nuclear Astrophysics Deep Underground

Nuclear astrophysics strives for a comprehensive picture of the nuclear reactions responsible for synthesizing chemical elements and for powering the stellar evolution engine. Deep underground in the Gran Sasso National Laboratory, the cross sections of the key reactions of the proton-proton chain and of the carbon-nitrogen-oxygen cycle have been measured right down to the energies of astrophysical interest. The salient features of underground nuclear astrophysics are summarized here. We review the main results obtained by LUNA during the past 20 years and discuss their influence on our understanding of the properties of the neutrino, the Sun, and the universe itself. Future directions of underground nuclear astrophysics toward the study both of helium and carbon burning and of stellar neutron sources in stars are outlined.

Electron screening effect in the reactions 3He(d, p)4He and d(3He, p)4He

The cross section of the reactions 3He(d, p)4He and d(3He, p)4He has been measured at the center-of-mass energies E=5 to 60 keV and 10 to 40 keV, respectively. The experiments were performed to determine the magnitude of the electron screening effect leading to the respective electron-screening potential energy Ue=219±7 and 109±9 eV, which are both significantly higher than the respective values from atomic physics models, Ue=120 and 65 eV.

A new setup for the underground study of capture reactions

For the study of astrophysically relevant capture reactions in the underground laboratory LUNA a newsetup of high sensitivity has been implemented. The setup includes a windowless gas target, a 4p BGO summing crystal, and beam calorimeters. The setup has been recently used to measure the d(p,g) 3 He cross-section for the first time within its solar Gamowpeak, i.e. dow n to 2.5 keV c.m. energy. The features of the optimized setup are described. r 2002 Elsevier Science B.V. All rights reserved.

Energy response of LR-115 cellulose nitrate to alpha-particle beams

Abstract By using α-particle beams from a Van de Graaff accelerator we have determined the energy response of LR-115 film. This information was subsequently used to optimize, by means of a numerical simulation, the thickness of the energy degrader in a typical radon sampler.

Determination of the Gamow–Teller strength function for the neutron-deficient isotopes 104–107In

Abstract The Gamow–Teller β decays of the neutron-deficient indium isotopes 104–107 In have been investigated by using total absorption γ -ray spectrometry on mass-separated sources. The experimental Gamow–Teller strength, deduced as a function of the excitation energy in the daughter nuclei 104–107 Cd, is compared to shell-model predictions.

Calibration of BP-1 phosphate glass with heavy-ion beams

Abstract Calibrations of BP-1 phosphate glass by means of 2.5 MeV amu-1 heavy-ion beams ranging from 12C to 24Mg, and for different etchants, are presented. The response of this glass to heavy ions is compared with that of other solid state nuclear track detectors.

From the Discovery of Cluster Radioactivity to Future Perspectives

A brief historical overview on the experimental work done in recent years on cluster radioactivity is given. The experimental techniques are discussed and a few most representative cases are presented. A few open problems are discussed, as far as the experimental and the theoretical interpretations are concerned.

The rp-process and new measurements of β-delayed proton decay of light Ag and Cd isotopes

Abstract Recent network calculations suggest that a high temperature rp-process could explain the abundances of light Mo and Ru isotopes, which have long challenged models of p-process nuclide production. Important ingredients to network calculations involving unstable nuclei near and at the proton drip line are β-halflives and decay modes, i.e., whether or not β-delayed proton decay takes place. Of particular importance to these network calculation are the proton-rich isotopes 96 Ag, 98 Ag, 96 Cd and 98 Cd. We report on recent measurements of β-delayed proton branching ratios for 96 Ag, 98 Ag, and 98 Cd at the on-line mass separator at GSI.

Measurement of exotic decay half lives with track detectors

Abstract Track detectors used in experimental studies of heavy ion radioactivity are briefly reviewed with particular emphasys on a recently developed phosphate glass, BP1. In addition we report on a new measurement of the 232 U 24 Ne + 208 Pb decay rate, which allows to update previous results for Ne emission from 234 U and 235 U.

The LUNA-MV Project at Gran Sasso Underground Laboratory

Since 1991, in the Gran Sasso underground Laboratory [1], in between the three main experimental halls where large collaborations run experiments on neutrinos and dark matter, a relatively small co...