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7Be decays via electron capture and therefore its half-life is expected to depend on the electron density at the nucleus. We measured the 7Be half-life in palladium, tungsten, zirconium and tantalum metals, in order to investigate the influence of the quasi-free electrons in metals on the probability of electron capture. The 7Be samples were obtained implanting a 4.85MeV pure radioactive 7Be ion beam. The 7Be half-life was determined measuring the 478keV gamma decay following the electron capture by means of HPGe detectors. In order to reduce systematic errors, we planned to perform independent measurements in three different laboratories: Naples (Italy), Bochum (Germany) and Debrecen (Hungary). On the basis of the first results, we do not find a 7Be half-life change within the experimental errors of 0.4%. [ABSTRACT FROM AUTHOR]

The Trojan Horse Method (THM) was applied to the 3He+ 7Li interaction in order to investigate the quasi-free 7Li(p,α)4He reaction. The three-body experiment was performed at 33 MeV corresponding to a 7Li-p relative energy ranging from 50keV to 7MeV. The extracted 7Li(p,α)4He quasi-free cross-section was compared with the behavior of direct data, as well as with the result of a previous THM investigation on the 7Li(p,α)4He reaction off the neutron in 2H. A good agreement between data sets shows up throughout the energy range investigated, providing a very important validity test of the pole approximation for the THM. [ABSTRACT FROM AUTHOR]

The elastic scattering cross section of 106Cd (α,α)106Cd has been measured with high accuracy at energies of E c.m. ≈ 15.5, 17, and 19MeV. The optical potential for the system 106Cd ⊗ α has been derived at energies above and below the Coulomb barrier. Predictions for the 106Cd (α,γ)110Sn capture cross section at astrophysically relevant energies are presented and compared to the experimental data measured recently. [ABSTRACT FROM AUTHOR]

The proton capture cross-sections of the two most proton-rich, stable isotopes of cadmium have been measured for the first time in the energy range relevant to the astrophysical p-process. The 106Cd (p,γ)107In and 108Cd (p,γ)109In cross-sections have been determined using the activation technique. Highly enriched as well as natural Cd targets have been irradiated with proton beams from both the Van de Graaff and Cyclotron accelerators of the ATOMKI. The cross-sections have been derived by measuring the γ-radiation following the β-decay of the 107In and 109In reaction products. The measurements were carried out in the energy range between 2.4 and 4.8MeV which is the relevant energy region (Gamow window) for the astrophysical p-process. Preliminary results are presented here and are compared with the predictions of the Hauser-Feshbach statistical model calculations using the NON-SMOKER code. [ABSTRACT FROM AUTHOR]

The 112Sn(α,γ)116Te reaction cross-section has been measured to test the applicability of statistical models, especially NON-SMOKER in the energy range of importance for the astrophysical p-process nucleosynthesis. The measurements were carried out at the Notre Dame FN Tandem Van de Graaff accelerator by means of the activation method. Enriched self-supporting foils were irradiated with alpha beams over the alpha bombarding energy range of 8MeV to 12MeV in 0.5MeV steps. The induced activity was measured with a pair of large volume Ge Clover detectors in close geometry to maximize the detection efficiency. The preliminary results are compared with recent statistical model predictions using the code NON-SMOKER. [ABSTRACT FROM AUTHOR]

An overview is given on the experimental nuclear physics aspects of the astrophysical p-process that is responsible for the production of the heavy proton-rich nuclei known as p-nuclei. The nuclear physics input of the p-process scenario involves the knowledge of radiative capture cross sections, mostly calculated by the Hauser–Feshbach statistical model. Our experiments test the reliability of the model calculations in the proton-rich region as well as provide experimental information on the cross sections relevant to the p-process.© 2004 MAIK “Nauka / Interperiodica”. [ABSTRACT FROM AUTHOR]

The absolute strengths of the Eα 1175 keV resonance in the 6Li(α, β)10B reaction and of the Eα = 814 keV resonance in the 7Li(α, γ )11B reaction have been measured to ωγ = 366 ± 38 meV and ωγ = 300 ± 32 meV, respectively, in good agreement with previous values. These resonances can be used to measure the absolute acceptance of the recoil separator ERNA to a precision of about 10%. [ABSTRACT FROM AUTHOR]

The electron screening effect in the d(d,p)t reaction has been studied for deuterated metals, insulators, and semiconductors, i.e. 58 samples in total. As compared to measurements performed with a gaseous D2 target, a large effect has been observed in most metals, while a small (gaseous) effect is found, e.g., for the insulators, semiconductors, and lanthanides. The periodic table provides the ordering of the observed small and large effects in the samples. An explanation of the large effects in metals is possibly provided by the classical plasma screening of Debye applied to the quasi-free metallic electrons. The data also provide information on the solubility of hydrogen in the samples. [ABSTRACT FROM AUTHOR]

In an earlier publication of Poyarkov and Sizov [1] an anomaly has been found in the position of some gamma lines from the decay of selected (p, γ) resonances, when observed in thick target experiments. No explanation was found for the effect. The reliability of their observation has been checked in the present work based on a repeated experiment for the case of the E =1699 keV resonance [4] in theC N reaction. Under the improved experimental conditions in this measurement the appearance of the anomaly has not been confirmed; with a more accurate energy position E =1688.7±0.7 keV the discrepancy between thin and thick target observations of the resonance has been resolved. [ABSTRACT FROM AUTHOR]

The cross section of the reactionGe( α, γ)Se has been measured over the bombarding energy range of 5.05 MeV < E < 7.80 MeV using single and coincidence gamma spectroscopy techniques. The experimental S-factor values are in agreement with theoretical statistical-model calculations. Reaction rates for theGe( α, γ)Se and the inverse ( γ, α) reactions have been determined for appropriate temperatures. [ABSTRACT FROM AUTHOR]

Excitation functions and forward-backward anisotropies have been measured for theLi( p, γ)Be capture reaction over the proton energy range E=100 to 1500 keV, using a 4π summing crystal and Ge(Li) detectors, respectively. The data show at all energies the presence of El and M1 capture amplitudes arising from the direct capture (DC) process and the E=441 and 1030 keV resonances, respectively. Due to the observed DC process, the present data increase significantly the reaction rates (up to a factor of 110) compared to values given in the compilation. The data and their analyses remove the recent criticism on DC model calculations, which had implied a significant reduction in the extrapolated S(E) factor forBe( p,γ)B and thus in the predicted flux of high-energy solar neutrinos; thus, the solar neutrino problem is still with us. [ABSTRACT FROM AUTHOR]

The fusion reactionsB( p, α)Be andB( p, α)Be have been studied over the c.m. energy range E=17 to 134 keV using intense proton beams and thick solid targets. In the case ofB( p, α)Be the low-energy data in terms of the astrophysical S( E) factor show an exponential enhancement (up to a factor of 1.9) due to the effects of electron screening, where the deduced screening potential is larger than expected. In the case ofB( p, α)Be the low-energy data exhibit an enhancement by more than a factor of 200, which cannot be explained by the effects of electron screening. The enhancement arises here from the high-energy tail of an expected s-wave resonance at E=10 keV. The results offer an improved prospect for this reaction as advanced fuel in future fusion reactors than previously envisioned. [ABSTRACT FROM AUTHOR]

The fusion reactionsLi( p, α)He,Li( d, α)He, andLi( p, α)He have been studied over the c.m. energy range E=10 to 1450 keV. Each reaction involved the use of hydrogen projectiles and LiF solid targets as well as Li projectiles and hydrogen molecular gas targets. In all cases the effects of electron screening on the low-energy fusion cross sections (exponential enhancement) have been observed; the effects are somewhat stronger in the case of atomic p or d projectiles compared to the case of molecular H or D gas targets. If isotopic effects on electron screening are negligible, all three reactions should exhibit the same enhancements for each set of experimental techniques. The measurements confirmed this expectation to a large extent. [ABSTRACT FROM AUTHOR]

The absolute cross section σ (E) of the radiative capture reaction p(7Be,γ)8B at the center-of-mass energy E = 992 keV has been measured using a radioactive 7Be ion beam and a windowless gas target system filled with H2 gas. The 8B residual nuclides were detected with a recoil separator consisting of momentum and velocity filters and a ΔE-E detector telescope. The 8B yield was observed concurrently with the 7Be + p elastic scattering yield, relating σ(E) to the Rutherford scattering cross section. The resulting value, σ(E) = 0.41 ± 0.11 μb, leads to an S(E) factor at zero energy of S(0) = 16 ± 4 eV b, in fair agreement with recommended values. [ABSTRACT FROM AUTHOR]

Differential cross sections for nonresonant radiative capture of low energy protons ( E = 1,348 keV and 1,370 keV) byNa nuclei exhibit features pointing to the virtual excitation of the giant dipole resonance (GDR) mode. Theoretical analysis carried out within the framework of the direct - semidirect capture model reveals an enhanced coupling of the GDR with the incident proton f-wave consistent with the microscopic structure of the GDR in the s-d shell nuclei. [ABSTRACT FROM AUTHOR]

The loss of 8Li recoil nuclei in 7Li(d,p)8Li has been measured using different backings and 7LiF target thicknesses as well as different deuteron energies. The results confirm essentially recent TRIM calculations. The losses are large (about 13%) for the combination of thin targets and heavy backings at Ed=0.80 MeV and increase with decreasing deuteron energy. The implications on the cross sections for 7Li(d,p)8Li and 7Be(p,γ)8B are discussed. [ABSTRACT FROM AUTHOR]