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1. Clarifying the radiative decay of the Hoyle state with charged-particle spectroscopy

Author

D. Dell’Aquila, I. Lombardo, L. Redigolo, M. Vigilante, F. Angelini, L. Baldesi, S. Barlini, A. Best, A. Camaiani, G. Casini, C. Ciampi, M. Cicerchia, M. D’Andrea, J. Diklić, D. Fabris, B. Gongora Servin, A. Gottardo, F. Gramegna, G. Imbriani, T. Marchi, A. Massara, D. Mengoni, A. Ordine, L. Palada, G. Pasquali, S. Piantelli, E. Pilotto, D. Rapagnani, M. Sigmund, A. Stefanini, D. Stramaccioni, D. Tagnani, I. Tišma, S. Valdré, G. Verde, and N. Vukman

Subjects
Medicine, Science
Abstract

Abstract A detailed knowledge of the decay properties of the so called Hoyle state in the $$^{12}$$ 12 C nucleus ( $$E_x=7.654$$ E x = 7.654 MeV, $$0^+$$ 0 + ) is required to calculate the rate at which carbon is forged in typical red-giant stars. This paper reports on a new almost background-free measurement of the radiative decay branching ratio of the Hoyle state using advanced charged particle coincidence techniques. The exploitation, for the first time in a similar experiment, of a bidimensional map of the coincidence efficiency allows to reach an unitary value and, consequently, to strongly reduce sources of systematic uncertainties. The present results suggest a value of the radiative branching ratio of $$\Gamma _{rad}/\Gamma _{tot}=4.2(6)\cdot 10^{-4}$$ Γ rad / Γ tot = 4.2 ( 6 ) · 10 - 4 . This finding helps to resolve the tension between recent data published in the literature.

Published
2024
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2. CLYC as a neutron detector in low background conditions

Author

J. Plaza, V. Bécares, D. Cano-Ott, C. Gómez, T. Martínez, E. Mendoza, A. Pérez de Rada, V. Pesudo, J. C. Sáez-Vergara, R. Santorelli, D. Villamarín, A. Ianni, C. Peña, J. Balibrea-Correa, A. Boeltzig, and G. Imbriani

Subjects
Astrophysics, QB460-466, Nuclear and particle physics. Atomic energy. Radioactivity, QC770-798
Abstract

Abstract We report on the thermal neutron flux measurements carried out at the Laboratorio Subterráneo de Canfranc (LSC) with two commercial $$2^{\prime \prime } \times 2^{\prime \prime }$$ 2 ″ × 2 ″ CLYC detectors. The measurements were performed as part of an experimental campaign at LSC with $$^{3}$$ 3 He detectors, for establishing the sensitivity limits and use of CLYCs in low background conditions. A careful characterization of the intrinsic $$\alpha $$ α and $$\gamma $$ γ -ray background in the detectors was required and done with dedicated measurements. It was found that the $$\alpha $$ α activities in the two CLYC crystals differ by a factor of three, and the use of Monte Carlo simulations and a Bayesian unfolding method allowed us to determine the specific $$\alpha $$ α activities from the $$^{238}$$ 238 U and $$^{232}$$ 232 Th decay chains. The simulations and unfolding also revealed that the $$\gamma $$ γ -ray background registered in the detectors is dominated by the intrinsic activity of the components of the detector such as the aluminum housing and photo-multiplier and that the activity within the crystal is low in comparison. The data from the neutron flux measurements with the two detectors were analyzed with different methodologies: one based on an innovative $$\alpha $$ α /neutron pulse shape discrimination method and one based on the subtraction of the intrinsic $$\alpha $$ α background that masks the neutron signals in the region of interest. The neutron sensitivity of the CLYCs was calculated by Monte Carlo simulations with MCNP6 and GEANT4. The resulting thermal neutron fluxes are in good agreement with complementary flux measurement performed with $$^{3}$$ 3 He detectors, but close to the detection limit imposed by the intrinsic $$\alpha $$ α activity.

Published
2023
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3. Direct measurements of low-energy resonance strengths of the 23Na(p,γ)24Mg reaction for astrophysics

Author

A. Boeltzig, A. Best, F.R. Pantaleo, G. Imbriani, M. Junker, M. Aliotta, J. Balibrea-Correa, D. Bemmerer, C. Broggini, C.G. Bruno, R. Buompane, A. Caciolli, F. Cavanna, T. Chillery, G.F. Ciani, P. Corvisiero, L. Csedreki, T. Davinson, R.J. deBoer, R. Depalo, A. Di Leva, Z. Elekes, F. Ferraro, E.M. Fiore, A. Formicola, Zs. Fülöp, G. Gervino, A. Guglielmetti, C. Gustavino, Gy. Gyürky, I. Kochanek, M. Lugaro, P. Marigo, R. Menegazzo, V. Mossa, F. Munnik, V. Paticchio, R. Perrino, D. Piatti, P. Prati, L. Schiavulli, K. Stöckel, O. Straniero, F. Strieder, T. Szücs, M.P. Takács, D. Trezzi, M. Wiescher, and S. Zavatarelli

Subjects
Physics, QC1-999
Abstract

The NeNa and the MgAl cycles play a fundamental role in the nucleosynthesis of asymptotic giant branch stars undergoing hot bottom burning. The Na23(p,γ)24Mg reaction links these two cycles and a precise determination of its rate is required to correctly estimate the contribution of these stars to the chemical evolution of various isotopes of Na, Mg and Al. At temperatures of 50≲T≲110MK, narrow resonances at Ep=140 and 251keV are the main contributors to the reaction rate, in addition to the direct capture that dominates in the lower part of the temperature range. We present new measurements of the strengths of these resonances at the Laboratory for Underground Nuclear Astrophysics (LUNA). We have used two complementary detection approaches: high efficiency with a 4π BGO detector for the 140keV resonance, and high resolution with a HPGe detector for the 251keV resonance. Thanks to the reduced cosmic ray background of LUNA, we were able to determine the resonance strength of the 251keV resonance as ωγ=482(82)μeV and observed new gamma ray transitions for the decay of the corresponding state in Mg24 at Ex=11931keV. With the highly efficient BGO detector, we observed a signal for the 140keV resonance for the first time in a direct measurement, resulting in a strength of ωγ140=1.46−0.53+0.58neV (68% CL). Our measurement reduces the uncertainty of the Na23(p,γ)24Mg reaction rate in the temperature range from 0.05 to 0.1GK to at most −35%+50% at 0.07GK. Accordingly, our results imply a significant reduction of the uncertainties in the nucleosynthesis calculations. Keywords: Experimental nuclear astrophysics, Underground nuclear physics, Hydrogen burning, Stellar evolution

Published
2019
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4. Improved astrophysical rate for the 18O(p,α)15N reaction by underground measurements

Author

C.G. Bruno, M. Aliotta, P. Descouvemont, A. Best, T. Davinson, D. Bemmerer, A. Boeltzig, C. Broggini, A. Caciolli, F. Cavanna, T. Chillery, G.F. Ciani, P. Corvisiero, R. Depalo, A. Di Leva, Z. Elekes, F. Ferraro, A. Formicola, Zs. Fülöp, G. Gervino, A. Guglielmetti, C. Gustavino, Gy. Gyürky, G. Imbriani, M. Junker, M. Lugaro, P. Marigo, R. Menegazzo, V. Mossa, F.R. Pantaleo, D. Piatti, P. Prati, K. Stöckel, O. Straniero, F. Strieder, T. Szücs, M.P. Takács, and D. Trezzi

Subjects
Physics, QC1-999
Abstract

The 18O(p,α)15N reaction affects the synthesis of 15N, 18O and 19F isotopes, whose abundances can be used to probe the nucleosynthesis and mixing processes occurring deep inside asymptotic giant branch (AGB) stars. We performed a low-background direct measurement of the 18O(p,α)15N reaction cross-section at the Laboratory for Underground Nuclear Astrophysics (LUNA) from center of mass energy Ec.m.=340 keV down to Ec.m.=55 keV, the lowest energy measured to date corresponding to a cross-section of less than 1 picobarn/sr. The strength of a key resonance at center of mass energy Er=90 keV was found to be a factor of 10 higher than previously reported. A multi-channel R-matrix analysis of our and other data available in the literature was performed. Over a wide temperature range, T=0.01–1.00 GK, our new astrophysical rate is both more accurate and precise than recent evaluations. Stronger constraints can now be placed on the physical processes controlling nucleosynthesis in AGB stars with interesting consequences on the abundance of 18O in these stars and in stardust grains, specifically on the production sites of oxygen-rich Group II grains. Keywords: Stellar hydrogen burning, Hydrostatic stellar nucleosynthesis

Published
2019
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5. Cross section of the reaction 18O(p,γ)19F at astrophysical energies: The 90 keV resonance and the direct capture component

Author

A. Best, F.R. Pantaleo, A. Boeltzig, G. Imbriani, M. Aliotta, J. Balibrea-Correa, D. Bemmerer, C. Broggini, C.G. Bruno, R. Buompane, A. Caciolli, F. Cavanna, T. Chillery, G.F. Ciani, P. Corvisiero, L. Csedreki, T. Davinson, R.J. deBoer, R. Depalo, A. Di Leva, Z. Elekes, F. Ferraro, E.M. Fiore, A. Formicola, Zs. Fülöp, G. Gervino, A. Guglielmetti, C. Gustavino, Gy. Gyürky, M. Junker, I. Kochanek, M. Lugaro, P. Marigo, R. Menegazzo, V. Mossa, V. Paticchio, R. Perrino, D. Piatti, P. Prati, L. Schiavulli, K. Stöckel, O. Straniero, F. Strieder, T. Szücs, M.P. Takács, D. Trezzi, M. Wiescher, and S. Zavatarelli

Subjects
Physics, QC1-999
Abstract

The observation of oxygen isotopes in giant stars sheds light on mixing processes operating in their interiors. Due to the very strong correlation between nuclear burning and mixing processes it is very important to reduce the uncertainty on the cross sections of the nuclear reactions that are involved. In this paper we focus our attention on the reaction O18(p,γ)19F. While the O18(p,α)15N channel is thought to be dominant, the (p,γ) channel can still be an important component in stellar burning in giants, depending on the low energy cross section. So far only extrapolations from higher-energy measurements exist and recent estimates vary by orders of magnitude. These large uncertainties call for an experimental reinvestigation of this reaction. We present a direct measurement of the O18(p,γ)19F cross section using a high-efficiency 4π BGO summing detector at the Laboratory for Underground Nuclear Astrophysics (LUNA). The reaction cross section has been directly determined for the first time from 140 keV down to 85 keV and the different cross section components have been obtained individually. The previously highly uncertain strength of the 90 keV resonance was found to be 0.53 ± 0.07 neV, three orders of magnitude lower than an indirect estimate based on nuclear properties of the resonant state and a factor of 20 lower than a recently established upper limit, excluding the possibility that the 90 keV resonance can contribute significantly to the stellar reaction rate. Keywords: Experimental nuclear astrophysics, Underground nuclear physics, Hydrogen burning, Stellar evolution

Published
2019
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7. Advances in radiative capture studies at LUNA with a segmented BGO detector

Author

J Skowronski, R M Gesuè, A Boeltzig, G F Ciani, D Piatti, D Rapagnani, M Aliotta, C Ananna, F Barile, D Bemmerer, A Best, C Broggini, C G Bruno, A Caciolli, M Campostrini, F Cavanna, P Colombetti, A Compagnucci, P Corvisiero, L Csedreki, T Davinson, R Depalo, A Di Leva, Z Elekes, F Ferraro, A Formicola, Zs Fülöp, G Gervino, A Guglielmetti, C Gustavino, Gy Gyürky, G Imbriani, M Junker, M Lugaro, P Marigo, E Masha, R Menegazzo, V Paticchio, R Perrino, P Prati, V Rigato, L Schiavulli, R S Sidhu, O Straniero, T Szücs, and S Zavatarelli

Subjects
Nuclear and High Energy Physics, gamma-ray total absorption spectroscopy, radiation shielding and background reduction, nuclear astrophysics experiment, activation measurement, segmented bismuth germanium oxide (BGO) detector, Settore FIS/04 - Fisica Nucleare e Subnucleare
Abstract

Studies of charged-particle reactions for low-energy nuclear astrophysics require high sensitivity, which can be achieved by means of detection setups with high efficiency and low backgrounds, to obtain precise measurements in the energy region of interest for stellar scenarios. High-efficiency total absorption spectroscopy is an established and powerful tool for studying radiative capture reactions, particularly if combined with the cosmic background reduction by several orders of magnitude obtained at the Laboratory for Underground Nuclear Astrophysics (LUNA). We present recent improvements in the detection setup with the Bismuth Germanium Oxide (BGO) detector at LUNA, aiming to reduce high-energy backgrounds and increase the summing detection efficiency. The new design results in enhanced sensitivity of the BGO setup, as we demonstrate and discuss in the context of the first direct measurement of the 65 keV resonance (E x = 5672 keV) of the 17O(p,γ)18F reaction. Moreover, we show two applications of the BGO detector, which exploit its segmentation. In the case of complex γ-ray cascades, e.g. the de-excitation of E x = 5672 keV in 18F, the BGO segmentation allows to identify and suppress the beam-induced background signals that mimic the sum peak of interest. We demonstrate another new application for such a detector in form of in situ activation measurements of a reaction with β + unstable product nuclei, e.g. the 14N(p,γ)15O reaction.

Published
2023
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9. Direct measurements of the $$^{12}$$C+$$^{12}$$C reactions cross-sections towards astrophysical energies

Author

L. Morales-Gallegos, M. Aliotta, L. Gialanella, A. Best, C. G. Bruno, R. Buompane, T. Davinson, M. De Cesare, A. Di Leva, A. D’Onofrio, J. G. Duarte, L. R. Gasques, G. Imbriani, G. Porzio, D. Rapagnani, M. Romoli, F. Terrasi, Morales-Gallegos, L., Aliotta, M., Gialanella, L., Best, A., Bruno, C. G., Buompane, R., Davinson, T., De Cesare, M., Di Leva, A., D'Onofrio, A., Duarte, J. G., Gasques, L. R., Imbriani, G., Porzio, G., Rapagnani, D., Romoli, M., and Terrasi, F.

Subjects
Nuclear and High Energy Physics, Experimental Nuclear Astrophysics Carbon burning in stars, ASTROFÍSICA
Abstract

Carbon fusion reactions $$^{12}$$ 12 C($$^{12}$$ 12 C,p)$$^{23}$$ 23 Na and $$^{12}$$ 12 C($$^{12}$$ 12 C,$$\alpha $$ α )$$^{20}$$ 20 Ne play a key role in the evolution of massive stars and in explosive scenarios such as type-Ia supernovae and super-bursts in binary stars. A direct determination of their cross sections is extremely challenging and discrepancies exist between different data sets in the literature. Here we report the results of a direct measurement performed at the CIRCE Tandem Accelerator Laboratory in Caserta (Italy), using $$\varDelta E-E$$ Δ E - E detectors for unambiguous charge identification. Cross sections were measured in the energy range $$E_{\mathrm{c.m.}} =2.51{-}4.36$$ E c . m . = 2.51 - 4.36 MeV with energy steps between 10 and 25 keV in the centre of mass. To our knowledge these represent the finest energy steps to date. Results are presented in the form of partial and summed astrophysical $${\tilde{S}}$$ S ~ -factors for individual proton- and $$\alpha $$ α -particle channels. Branching ratios of individual proton- and $$\alpha $$ α -particle groups were found to vary significantly with energy. Angular distributions, albeit limited to three angles, were also found to be non-isotropic, which could be a potential explanation for the discrepancies observed among different data sets. Further efforts are ongoing to extend measurements to lower energies.

Published
2022
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11. Introduction to experimental nuclear astrophysics

Author

A. Formicola and G. Imbriani

Subjects
Physics, Nuclear physics, 010308 nuclear & particles physics, Nucleosynthesis, 0103 physical sciences, Underground laboratory, Nuclear astrophysics, Measure (physics), General Physics and Astronomy, 010306 general physics, 01 natural sciences
Abstract

The present contribution aims to present some general features of the experimental approaches in Nuclear Astrophysics. After a general introduction on light elements nucleosynthesis and on how to determine the reaction rates in a stellar environment, we will focus our attention on underground experiments aimed to directly measure nuclear cross sections of astrophysics interest. We will discuss the 14N(p, $ \gamma$ )15O and 12C + 12C reactions, underlying the advantages in approaching these measurements in a deep underground laboratory, as the Laboratori Nazionali del Gran Sasso.

Published
2019
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12. Erratum: Three New Low-Energy Resonances in the ^{22}Ne(p,γ)^{23}Na Reaction [Phys. Rev. Lett. 115, 252501 (2015)]

Author

F, Cavanna, R, Depalo, M, Aliotta, M, Anders, D, Bemmerer, A, Best, A, Boeltzig, C, Broggini, C G, Bruno, A, Caciolli, P, Corvisiero, T, Davinson, A, di Leva, Z, Elekes, F, Ferraro, A, Formicola, Zs, Fülöp, G, Gervino, A, Guglielmetti, C, Gustavino, Gy, Gyürky, G, Imbriani, M, Junker, R, Menegazzo, V, Mossa, F R, Pantaleo, P, Prati, D A, Scott, E, Somorjai, O, Straniero, F, Strieder, T, Szücs, M P, Takács, and D, Trezzi

Abstract

This corrects the article DOI: 10.1103/PhysRevLett.115.252501.

Published
2018

14. Cross section measurement ofN14(p,γ)O15in the CNO cycle

Author

A. Kontos, Ethan Uberseder, P. J. LeBlanc, Joachim Görres, G. Imbriani, A. Best, Q. Li, Michael Wiescher, and Richard deBoer

Subjects
Physics, Excitation function, CNO cycle, 010308 nuclear & particles physics, Resonance, 01 natural sciences, Excited state, 0103 physical sciences, Production (computer science), Atomic physics, 010306 general physics, Ground state, Energy source, Energy (signal processing)
Abstract

Background: The CNO cycle is the main energy source in stars more massive than our sun; it defines the energy production and the cycle time that lead to the lifetime of massive stars, and it is an important tool for the determination of the age of globular clusters. In our sun about 1.6% of the total solar neutrino flux comes from the CNO cycle. The largest uncertainty in the prediction of this CNO flux from the standard solar model comes from the uncertainty in the $^{14}\mathrm{N}(p,\ensuremath{\gamma})^{15}\mathrm{O}$ reaction rate; thus, the determination of the cross section at astrophysical temperatures is of great interest.Purpose: The total cross section of the $^{14}\mathrm{N}(p,\ensuremath{\gamma})^{15}\mathrm{O}$ reaction has large contributions from the transitions to the ${E}_{x}=6.79\phantom{\rule{4pt}{0ex}}\mathrm{MeV}$ excited state and the ground state of $^{15}\mathrm{O}$. The ${E}_{x}=6.79\phantom{\rule{4pt}{0ex}}\mathrm{MeV}$ transition is dominated by radiative direct capture, while the ground state is a complex mixture of direct and resonance capture components and the interferences between them. Recent studies have concentrated on cross-section measurements at very low energies, but broad resonances at higher energy may also play a role. A single measurement has been made that covers a broad higher-energy range but it has large uncertainties stemming from uncorrected summing effects. Furthermore, the extrapolations of the cross section vary significantly depending on the data sets considered. Thus, new direct measurements have been made to improve the previous high-energy studies and to better constrain the extrapolation.Methods: Measurements were performed at the low-energy accelerator facilities of the nuclear science laboratory at the University of Notre Dame. The cross section was measured over the proton energy range from ${E}_{p}=0.7$ to 3.6 MeV for both the ground state and the ${E}_{x}=6.79\phantom{\rule{4.pt}{0ex}}\mathrm{MeV}$ transitions at ${\ensuremath{\theta}}_{\text{lab}}={0}^{\ensuremath{\circ}}$, ${45}^{\ensuremath{\circ}}$, ${90}^{\ensuremath{\circ}}$, ${135}^{\ensuremath{\circ}}$, and ${150}^{\ensuremath{\circ}}$. Both TiN and implanted-$^{14}\mathrm{N}$ targets were utilized. $\ensuremath{\gamma}$ rays were detected by using an array of high-purity germanium detectors.Results: The excitation function as well as angular distributions of the two transitions were measured. A multichannel $R$-matrix analysis was performed with the present data and is compared with previous measurements. The analysis covers a wide energy range so that the contributions from broad resonances and direct capture can be better constrained.Conclusion: The astrophysical $S$ factors of the ${E}_{x}=6.79\phantom{\rule{4.pt}{0ex}}\mathrm{MeV}$ and the ground-state transitions were extrapolated to low energies with the newly measured differential-cross-section data. Based on the present work, the extrapolations yield ${S}_{6.79}(0)=1.29\ifmmode\pm\else\textpm\fi{}0.04(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.09(\mathrm{syst})\phantom{\rule{4pt}{0ex}}\mathrm{keV}\phantom{\rule{0.16em}{0ex}}\mathrm{b}$ and ${S}_{\text{g.s.}}(0)=0.42\ifmmode\pm\else\textpm\fi{}0.04(\mathrm{stat})\phantom{\rule{4pt}{0ex}}\mathrm{keV}\phantom{\rule{0.16em}{0ex}}\mathrm{b}$. While significant improvement and consistency is found in modeling the ${E}_{x}=6.79\phantom{\rule{4.pt}{0ex}}\mathrm{MeV}$ transition, large inconsistencies in both the $R$-matrix fitting and the low-energy data are reaffirmed for the ground-state transition. Reflecting this, a systematic uncertainty of ${}_{\ensuremath{-}0.19}^{+0.09}\phantom{\rule{4pt}{0ex}}\mathrm{keV}\phantom{\rule{0.16em}{0ex}}\mathrm{b}$ is recommended for the ground-state transition.

Published
2016
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15. Ultra-sensitive γ-ray spectroscopy set-up for investigating primordial lithium problem

Author

Daniel Bemmerer, A. DiLeva, C. Broggini, C. Gustavino, A. Formicola, Tamás Szücs, A. Boeltzig, Oscar Straniero, Z. Elekes, Marialuisa Aliotta, Gy. Gyürky, G. Gervino, F. Cavanna, P. Corvisiero, Rosanna Depalo, A. Best, A. Guglielmetti, Zs. Fülöp, David Scott, M. Junker, G. Imbriani, M. Anders, Paolo Prati, C. G. Bruno, Roberto Menegazzo, Thomas Davinson, Antonio Caciolli, Davide Trezzi, F. Ferraro, Gervino, G., Gustavino, C., Trezzi, D., Aliotta, M., Anders, M., Boeltzig, A., Bemmerer, D., Best, A., Broggini, C., Bruno, C., Caciolli, A., Cavanna, F., Corvisiero, P., Davinson, T., Depalo, R., Dileva, A., Elekes, Z., Ferraro, F., Formicola, A., Fülöp, Zs., Guglielmetti, A., Gyürky, Gy., Imbriani, G., Junker, M., Menegazzo, R., Prati, P., Scott, D. A., Straniero, O., and Szücs, T.

Subjects
Nuclear reaction, Physics, Nuclear and High Energy Physics, Spectrometer, 010308 nuclear & particles physics, chemistry.chemical_element, Underground Physic, 01 natural sciences, Spectral line, Semiconductor detector, Lithium problem, Nuclear physics, Deuterium, chemistry, Gamma spectroscopy, 0103 physical sciences, Neutron, Lithium, 010306 general physics, Spectroscopy, Instrumentation, Gamma spectroscopy Underground Physics Lithium problem, Nuclear and High Energy Physic
Abstract

To precisely determine BBN 6 Li production, the cross-section of the nuclear reaction 2 H(α, γ) 6 Li must be directly measured within the astrophysical energy range of 30–400 keV. This measure requires an ultra-low γ-ray background in the experimental set-up. We have realized the conditions matching these very strict requirements at LUNA, the deep underground accelerator laboratory active in the INFN Gran Sasso National Laboratory (LNGS), Italy: the γ-ray spectrometer background has been reduced down to reach unmatched low levels, comparable to the good ones experienced in dedicated off-line underground ultra low γ counting rate. We present and discuss the γ-ray background reduction reached in the HpGe spectrometer, where most of the remaining γ-ray background seen in the spectra are coming from the energetic deuterons scattered in the gas target by the α beam. Thanks to the low neutron environmental background at LUNA, the effect of this weak flux of 2–3 MeV neutrons on HpGe detectors has been studied in details and the results are presented and discussed.

Published
2016

16. Impact of a revised 25Mg(p, γ)26Al reaction rate on the operation of the Mg-Al cycle

Author

O. Straniero, G. Imbriani, F. Strieder, D. Bemmerer, C. Broggini, A. Caciolli, P. Corvisiero, H. Costantini, S. Cristallo, A. Dileva, A. Formicola, Elekes Z. Fülöp, G. Gervino, A. Guglielmetti, C. Gustavino, G. Gyürky, M. Junker, A. Lemut, B. Limata, M. Marta, C. Mazzocchi, R. Menegazzo, L. Piersanti, P. Prati, V. Roca, C. Rolfs, C. Rossi Alvarez, E. Somorjai, H. P. Trautvetter, H. P., TERRASI, Filippo, O., Straniero, G., Imbriani, F., Strieder, D., Bemmerer, C., Broggini, A., Caciolli, P., Corvisiero, H., Costantini, S., Cristallo, A., Dileva, A., Formicola, Elekes Z., Fülöp, G., Gervino, A., Guglielmetti, C., Gustavino, G., Gyürky, M., Junker, A., Lemut, B., Limata, M., Marta, C., Mazzocchi, R., Menegazzo, L., Piersanti, P., Prati, V., Roca, C., Rolf, C., Rossi Alvarez, E., Somorjai, Terrasi, Filippo, H. P., Trautvetter, and H., P.

Published
2013

17. Electron screening in d(d, p)t for deuterated metals: temperature effects

Author

F Raiola, the LUNA Collaboration, B Burchard, Z Fülöp, G Gyürky, S Zeng, J Cruz, A Di Leva, B Limata, M Fonseca, H Luis, M Aliotta, H W Becker, C Broggini, A DÒnofrio, L Gialanella, G Imbriani, A P Jesus, M Junker, J P Ribeiro, V Roca, C Rolfs, M Romano, E Somorjai, F Strieder, F Terrasi, F., Raiola, the LUNA, Collaboration, B., Burchard, Z., Fülöp, G., Gyürky, S., Zeng, J., Cruz, DI LEVA, Antonino, Limata, BENEDICTA NORMANNA, M., Fonseca, H., Lui, M., Aliotta, H. W., Becker, C., Broggini, A., Dònofrio, L., Gialanella, Imbriani, Gianluca, A. P., Jesu, M., Junker, J. P., Ribeiro, Roca, Vincenzo, C., Rolf, Romano, Mario, E., Somorjai, F., Strieder, and F., Terrasi

Subjects
Physics, Nuclear and High Energy Physics, Hydrogen, Screening effect, Analytical chemistry, chemistry.chemical_element, Metal, symbols.namesake, Deuterium, chemistry, visual_art, Atom, visual_art.visual_art_medium, symbols, Solubility, Atomic physics, Valence electron, Debye model
Abstract

The electron screening in the d(d, p)t reaction has been studied for the deuterated metal Pt at a sample temperature T = 20 ◦C–340 ◦C and for Co at T = 20 ◦C and 200 ◦C. The enhanced electron screening decreases with increasing temperature, where the data agree with the plasma model of Debye applied to the quasi-free metallic electrons. The data represent the first observation of a temperature dependence of a nuclear cross section. We also measured the screening effect for the deuterated metal Ti (an element of group 4 of the periodic table) at T = −10 ◦C–200 ◦C: above 50 ◦C, the hydrogen solubility dropped to values far below 1 and a large screening effect became observable. Similarly, all metals of groups 3 and 4 and the lanthanides showed a solubility of a few per cent at T=200 ◦C (compared to T=20 ◦C) and a large screening also became observable. Within the Debye model, the deduced number of valence electrons per metallic atom agrees with the corresponding number from the Hall coefficient, for all metals investigated. (Some figures in this article are in colour only in the

Published
2005
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18. The 25Mg(p, γ) 26Al reaction at low astrophysical energies.Physics Letters B707(2012)60

Author

F. Strieder, B. Limata, A. Formicola, G. Imbriani, M. Junker, D. Bemmerer, C. Broggini, A. Caciolli, P. Corvisiero, H. Costantini, A. DiLeva, Z. Elekes, Z. Fülöp, G. Gervino, A. Guglielmetti, C. Gustavino, G. Gyürky, A. Lemut, M. Marta, C. Mazzocchi, R. Menegazzo, P. Prati, V. Roca, C. Rolfs, C. Rossi Alvarez, E. Somorjai, O. Straniero, H. P. Trautvetter, TERRASI, Filippo, F., Strieder, B., Limata, A., Formicola, G., Imbriani, M., Junker, D., Bemmerer, C., Broggini, A., Caciolli, P., Corvisiero, H., Costantini, A., Dileva, Z., Eleke, Z., Fülöp, G., Gervino, A., Guglielmetti, C., Gustavino, G., Gyürky, A., Lemut, M., Marta, C., Mazzocchi, R., Menegazzo, P., Prati, V., Roca, C., Rolf, C., Rossi Alvarez, E., Somorjai, O., Straniero, Terrasi, Filippo, and H. P., Trautvetter

Published
2012

19. Revision of the 15N(p, γ)16O reaction rate and oxygen abundance in H-burning zones Astronomy & Astrophysics 533(2011)

Author

A. Caciolli, C. Mazzocchi, V. Capogrosso, D. Bemmerer, C. Broggini, P. Corvisiero, H. Costantini, Z. Elekes, A. Formicola, Z.s. Fülöp, G. Gervino, A. Guglielmetti, C. Gustavino, G.y. Gyürky, G. Imbriani, M. Junker, A. Lemut, M. Marta, R. Menegazzo, S. Palmerini, P. Prati, V. Roca, C. Rolfs, C. Rossi Alvarez, E. Somorjai, O. Straniero, F. Strieder, H. P. Trautvetter, A. Vomiero, TERRASI, Filippo, A., Caciolli, C., Mazzocchi, V., Capogrosso, D., Bemmerer, C., Broggini, P., Corvisiero, H., Costantini, Z., Eleke, A., Formicola, Fülöp, Z. s., G., Gervino, A., Guglielmetti, C., Gustavino, Gyürky, G. y., G., Imbriani, M., Junker, A., Lemut, M., Marta, R., Menegazzo, S., Palmerini, P., Prati, V., Roca, C., Rolf, C., Rossi Alvarez, E., Somorjai, O., Straniero, F., Strieder, Terrasi, Filippo, H. P., Trautvetter, and A., Vomiero

Subjects
stars: AGB and post-AGB – nuclear reactions, nucleosynthesis, abundances – novae – cataclysmic variables
Abstract

Context. The NO cycle takes place in the deepest layer of a H-burning core or shell, when the temperature exceeds T 30 × 106 K. The O depletion observed in some globular cluster giant stars, always associated with a Na enhancement, may be due to either a deep mixing during the red giant branch (RGB) phase of the star or to the pollution of the primordial gas by an early population of massive asymptotic giant branch (AGB) stars, whose chemical composition was modified by the hot bottom burning. In both cases, the NO cycle is responsible for the O depletion. Aims. The activation of this cycle depends on the rate of the 15N(p, γ)16O reaction. A precise evaluation of this reaction rate at temperatures as low as experienced in H-burning zones in stellar interiors is mandatory to understand the observed O abundances. Methods. We present a new measurement of the 15N(p, γ)16O reaction performed at LUNA covering for the first time the center of mass energy range 70−370 keV, which corresponds to stellar temperatures between 65 × 106 K and 780 × 106 K. This range includes the 15N(p, γ)16O Gamow-peak energy of explosive H-burning taking place in the external layer of a nova and the one of the hot bottom burning (HBB) nucleosynthesis occurring in massive AGB stars. Results. With the present data, we are also able to confirm the result of the previous R-matrix extrapolation. In particular, in the temperature range of astrophysical interest, the new rate is about a factor of 2 smaller than reported in the widely adopted compilation of reaction rates (NACRE or CF88) and the uncertainty is now reduced down to the 10% level.

Published
2011

20. The N14(p,γ)O15 reaction studied with a composite germanium detector Physical Review C83(2011)045804

Author

M. Marta, A. Formicola, D. Bemmerer, C. Broggini, A. Caciolli, P. Corvisiero, H. Costantini, Z. Elekes, Z. Fülöp, G. Gervino, A. Guglielmetti, C. Gustavino, G. Gyürky, G. Imbriani, M. Junker, A. Lemut, B. Limata, C. Mazzocchi, R. Menegazzo, P. Prati, V. Roca, C. Rolfs, C. Rossi Alvarez, E. Somorjai, O. Straniero, F. Strieder, H. P. Trautvetter, A. Vomiero, TERRASI, Filippo, M., Marta, A., Formicola, D., Bemmerer, C., Broggini, A., Caciolli, P., Corvisiero, H., Costantini, Z., Eleke, Z., Fülöp, G., Gervino, A., Guglielmetti, C., Gustavino, G., Gyürky, G., Imbriani, M., Junker, A., Lemut, B., Limata, C., Mazzocchi, R., Menegazzo, P., Prati, V., Roca, C., Rolf, C., Rossi Alvarez, E., Somorjai, O., Straniero, F., Strieder, Terrasi, Filippo, H. P., Trautvetter, and A., Vomiero

Published
2011

21. Constraining the S factor of N15(p,γ)O16 at astrophysical energies

Author

P. J. Leblanc, G. Imbriani, J. Görres, M. Junker, R. Azuma, M. Beard, D. Bemmerer, A. Best, C. Broggini, A. Caciolli, P. Corvisiero, H. Costantini, M. Couder, R. Deboer, Z. Elekes, S. Falahat, A. Formicola, Z. Fülöp, G. Gervino, A. Guglielmetti, C. Gustavino, G. Gyürky, F. Käppeler, A. Kontos, R. Kuntz, H. Leiste, A. Lemut, Q. Li, B. Limata, M. Marta, C. Mazzocchi, R. Menegazzo, S. O'Brien, A. Palumbo, P. Prati, V. Roca, C. Rolfs, C. Rossi Alvarez, E. Somorjai, E. Stech, O. Straniero, F. Strieder, W. Tan, H. P. Trautvetter, E. Uberseder, M. Wiescher, TERRASI, Filippo, P. J., Leblanc, G., Imbriani, J., Görre, M., Junker, R., Azuma, M., Beard, D., Bemmerer, A., Best, C., Broggini, A., Caciolli, P., Corvisiero, H., Costantini, M., Couder, R., Deboer, Z., Eleke, S., Falahat, A., Formicola, Z., Fülöp, G., Gervino, A., Guglielmetti, C., Gustavino, G., Gyürky, F., Käppeler, A., Konto, R., Kuntz, H., Leiste, A., Lemut, Q., Li, B., Limata, M., Marta, C., Mazzocchi, R., Menegazzo, S., O'Brien, A., Palumbo, P., Prati, V., Roca, C., Rolf, C., Rossi Alvarez, E., Somorjai, E., Stech, O., Straniero, F., Strieder, W., Tan, Terrasi, Filippo, H. P., Trautvetter, E., Uberseder, and M., Wiescher

Published
2010

22. An actively vetoed Clover gamma-detector for nuclear astrophysics at LUNA. Eur. Phys. J. A44(2010)513-519

Author

T. SZUCS, D. BEMMERER, C. BROGGINI, A. CACIOLLI, F. CONFORTOLA, P. CORVISIERO, Z. ELEKES, A. FORMICOLA, Z.S. FULOP, G. GERVINO, A. GUGLIELMETTI, C. GUSTAVINO, G.Y. GYURKY, G. IMBRIANI, M. JUNKER, A. LEMUT, M. MARTA, C. MAZZOCCHI, R. MENEGAZZO, P. PRATI, V. ROCA, C. ROLFS, C. ROSSI ALVAREZ, E. SOMORJAI, O. STRANIERO, F. STRIEDER, H. P. TRAUTVETTER, TERRASI, Filippo, T., Szuc, D., Bemmerer, C., Broggini, A., Caciolli, F., Confortola, P., Corvisiero, Z., Eleke, A., Formicola, Fulop, Z. S., G., Gervino, A., Guglielmetti, C., Gustavino, Gyurky, G. Y., G., Imbriani, M., Junker, A., Lemut, M., Marta, C., Mazzocchi, R., Menegazzo, P., Prati, V., Roca, C., Rolf, C., ROSSI ALVAREZ, E., Somorjai, O., Straniero, F., Strieder, Terrasi, Filippo, and H. P., Trautvetter

Published
2010

23. New experimental study of low-energy (p,γ) resonances in magnesium isotopes. Phys. Rev. C82(2010)015801

Author

B. LIMATA, F. STRIEDER, A. FORMICOLA, G. IMBRIANI, M. JUNKER, H. W. BECKER, D. BEMMERER, A. BEST, R. BONETTI, C. BROGGINI, A. CACIOLLI, P. CORVISIERO, H. COSTANTINI, A. DILEVA, Z. ELEKES, Z.S. FÜLÖP, G. GERVINO, A. GUGLIELMETTI, C. GUSTAVINO, G.Y. GYÜRKY, A. LEMUT, M. MARTA, C. MAZZOCCHI, R. MENEGAZZO, P. PRATI, V. ROCA, C. ROLFS, C. ROSSI ALVAREZ, C. SALVO, E. SOMORJAI, O. STRANIERO, AND H. P. TRAUTVETTER, TERRASI, Filippo, B., Limata, F., Strieder, A., Formicola, G., Imbriani, M., Junker, H. W., Becker, D., Bemmerer, A., Best, R., Bonetti, C., Broggini, A., Caciolli, P., Corvisiero, H., Costantini, A., Dileva, Z., Eleke, Fülöp, Z. S., G., Gervino, A., Guglielmetti, C., Gustavino, Gyürky, G. Y., A., Lemut, M., Marta, C., Mazzocchi, R., Menegazzo, P., Prati, V., Roca, C., Rolf, C., ROSSI ALVAREZ, C., Salvo, E., Somorjai, O., Straniero, Terrasi, Filippo, and AND H. P., Trautvetter

Published
2010

24. Impact of the uncertainty in alpha-captures on 22Ne on the weak s-process in massive stars

Author

Marco Pignatari, G. Imbriani, J. Görres, M. Wiescher, M. Beard, Raphael Hirschi, Richard deBoer, N. Nishimura, F. Herwig, Nishimura, N., Hirschi, R., Pignatari, M., Herwig, F., Beard, M., Imbriani, G., Görres, J., Deboer, R. J., and Wiescher, M.

Subjects
Physics, stellar evolution, s-proce, Metallicity, 020206 networking & telecommunications, 02 engineering and technology, Giant star, 7. Clean energy, Nuclear physics, Physics and Astronomy (all), Stars, Nucleosynthesis, 0202 electrical engineering, electronic engineering, information engineering, Neutron source, Astrophysics::Solar and Stellar Astrophysics, 020201 artificial intelligence & image processing, Neutron, s-process, Astrophysics::Galaxy Astrophysics, Oxygen-16
Abstract

Massive stars at solar metallicity contribute to the production of heavy elements with atomic masses between A = 60 and A = 90 via the so called weak s process (which takes place during core He and shell C burning phases). Furthermore recent studies have shown that rotation boosts the s process production in massive stars at low metallicities with a production that may reach the barium neutron magic peak. These results are very sensitive to neutron source and neutron poison reaction rates. For the weak s process the main neutron source is the reaction 22Ne(alphan)25Mg which is in competition with 22Ne(alphagamma)26Mg. The uncertainty of both rates strongly affects the nucleosynthesis predictions from stellar model calculations. In this study we investigate the impact of the uncertainty in alpha captures on 22Ne on the s process nucleosynthesis in massive stars both at solar and at very low metallicity. For this purpose we post process with the Nugrid mppnp code non rotating and rotating evolutionary models 25Msun; stars at two different metallicities: Z = Zsun; and Z = 10 5Zsun; respectively. Our results show that uncertainty of 22Ne(alphan)25Mg and 22Ne(alphagamma)26Mg rates have a significant impact on the final elemental production especially for metal poor rotating models. Beside uncertainties in the neutron source reactions for fast rotating massive stars at low metallicity we revisit the impact of the neutron poisoning effect by the reaction chain 16O(ngamma)17O(alphagamma)21Ne in competition with the 17O(alphan)20Ne recycling the neutrons captured by 16O.

Published
2014
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25. The 3He(α,γ)7Be S-factor at solar energies: the prompt &gamma experiment at LUNA

Author

H. COSTANTINI, D. BEMMERER, F. CONFORTOLA, A. FORMICOLA, G.Y. GYURKY, P. BEZZON, R. BONETTI, C. BROGGINI, P. CORVISIERO, Z. ELEKES, Z.S. FULOP, G. GERVINO, A. GUGLIELMETTI, C. GUSTAVINO, G. IMBRIANI, M. JUNKER, M. LAUBENSTEIN, A. LEMUT, B. LIMATA, V. LOZZA, M. MARTA, R. MENEGAZZO, P. PRATI, V. ROCA, C. ROLFS, C. ROSSI ALVAREZ, E. SOMORJAI, O. STRANIERO, F. STRIEDER, H. P. TRAUTVETTER, TERRASI, Filippo, H., Costantini, D., Bemmerer, F., Confortola, A., Formicola, Gyurky, G. Y., P., Bezzon, R., Bonetti, C., Broggini, P., Corvisiero, Z., Eleke, Fulop, Z. S., G., Gervino, A., Guglielmetti, C., Gustavino, G., Imbriani, M., Junker, M., Laubenstein, A., Lemut, B., Limata, V., Lozza, M., Marta, R., Menegazzo, P., Prati, V., Roca, C., Rolf, C., ROSSI ALVAREZ, E., Somorjai, O., Straniero, F., Strieder, Terrasi, Filippo, and H. P., Trautvetter

Published
2008

26. 3He(alpha,gamma)7Be cross section at low energies

Author

G.Y. GYÜRKY, F. CONFORTOLA, H. COSTANTINI, A. FORMICOLA, D. BEMMERER, R. BONETTI, C. BROGGINI, P. CORVISIERO, Z. ELEKES, Z.S. FÜLÖP, G. GERVINO, A. GUGLIELMETTI, C. GUSTAVINO, G. IMBRIANI, M. JUNKER, M. LAUBENSTEIN, A. LEMUT, B. LIMATA, M. MARTA, R. MENEGAZZO, P. PRATI, V. ROCA, C. ROLFS, C. ROSSI ALVAREZ, E. SOMORJAI, O. STRANIERO, F. STRIEDER, F. TERRASI, H. P. TRAUTVETTER, LOZZA, VALENTINA, Gyürky, G. Y., F., Confortola, H., Costantini, A., Formicola, D., Bemmerer, R., Bonetti, C., Broggini, P., Corvisiero, Z., Eleke, Fülöp, Z. S., G., Gervino, A., Guglielmetti, C., Gustavino, G., Imbriani, M., Junker, M., Laubenstein, A., Lemut, B., Limata, Lozza, Valentina, M., Marta, R., Menegazzo, P., Prati, V., Roca, C., Rolf, C., ROSSI ALVAREZ, E., Somorjai, O., Straniero, F., Strieder, F., Terrasi, and H. P., Trautvetter

Subjects
Astrophysics (astro-ph), FOS: Physical sciences, Nuclear Experiment (nucl-ex), Astrophysics, Nuclear Experiment
Abstract

The flux of 7Be and 8B neutrinos from the Sun and the production of 7Li via primordial nucleosynthesis depend on the rate of the 3He(alpha,gamma)7Be reaction. In extension of a previous study showing cross section data at 127 - 167 keV center of mass energy, the present work reports on a measurement of the 3He(alpha,gamma)7Be cross section at 106 keV performed at Italy's Gran Sasso underground laboratory by the activation method. This energy is closer to the solar Gamow energy than ever reached before. The result is sigma = 0.567 +- 0.029(stat) +- 0.016(syst) nbarn. The data are compared with previous activation studies at high energy, and a recommended S(0) value for all 3He(alpha,gamma)7Be activation studies, including the present work, is given., Accepted for publication in PRC

Published
2007

27. Astrophysical S factor of the 3He(alpha,gamma)7Be reaction measured at low energy via detection of prompt and delayed gamma rays

Author

F. CONFORTOLA, D. BEMMERER, H. COSTANTINI, A. FORMICOLA, G.Y. GYÜRKY, P. BEZZON, R. BONETTI, C. BROGGINI, P. CORVISIERO, Z. ELEKES, Z.S. FÜLÖP, G. GERVINO, A. GUGLIELMETTI, C. GUSTAVINO, G. IMBRIANI, M. JUNKER, M. LAUBENSTEIN, A. LEMUT, B. LIMATA, M. MARTA, R. MENEGAZZO, P. PRATI, V. ROCA, C. ROLFS, C. ROSSI ALVAREZ, E. SOMORJAI, O. STRANIERO, F. STRIEDER, F. TERRASI, H. P. TRAUTVETTER, LOZZA, VALENTINA, F., Confortola, D., Bemmerer, H., Costantini, A., Formicola, Gyürky, G. Y., P., Bezzon, R., Bonetti, C., Broggini, P., Corvisiero, Z., Eleke, Fülöp, Z. S., G., Gervino, A., Guglielmetti, C., Gustavino, G., Imbriani, M., Junker, M., Laubenstein, A., Lemut, B., Limata, Lozza, Valentina, M., Marta, R., Menegazzo, P., Prati, V., Roca, C., Rolf, C., ROSSI ALVAREZ, E., Somorjai, O., Straniero, F., Strieder, F., Terrasi, and H. P., Trautvetter

Published
2007

28. Activation measurement of the 3He(a,g)7Be cross section at low energy

Author

D. BEMMERER, F. CONFORTOLA, H. COSTANTINI, A. FORMICOLA, G. GYU, RKY, R. BONETTI, C. BROGGINI, P. CORVISIERO, Z. ELEKES, Z. FU, LOP, G. GERVINO, A. GUGLIELMETTI, C. GUSTAVINO, G. IMBRIANI, M. JUNKER, M. LAUBENSTEIN, A. LEMUT, B. LIMATA, V. LOZZA, M. MARTA, R. MENEGAZZO, P. PRATI, V. ROCA, C. ROLFS, C. ROSSI ALVAREZ, E. SOMORJAI, O. STRANIERO, F. STRIEDER, H. P. TRAUTVETTER, TERRASI, Filippo, D., Bemmerer, F., Confortola, H., Costantini, A., Formicola, G., Gyu, Rky, R., Bonetti, C., Broggini, P., Corvisiero, Z., Eleke, Z., Fu, Lop, G., Gervino, A., Guglielmetti, C., Gustavino, G., Imbriani, M., Junker, M., Laubenstein, A., Lemut, B., Limata, V., Lozza, M., Marta, R., Menegazzo, P., Prati, V., Roca, C., Rolf, C., ROSSI ALVAREZ, E., Somorjai, O., Straniero, F., Strieder, Terrasi, Filippo, and H. P., Trautvetter

Published
2006

29. Low energy measurement of the 14N(p,γ)15O total cross section at the LUNA underground facility

Author

D. BEMMERER, F. CONFORTOLA, H. COSTANTINI, A. FORMICOLA, G. GYU, RKY, R. BONETTI, C. BROGGINI, P. CORVISIERO, Z. ELEKES, Z. FU, LOP, G. GERVINO, A. GUGLIELMETTI, C. GUSTAVINO, G. IMBRIANI, M. JUNKER, M. LAUBENSTEIN, A. LEMUT, B. LIMATA, V. LOZZA, M. MARTA, R. MENEGAZZO, P. PRATI, V. ROCA, C. ROLFS, C. ROSSI ALVAREZ, E. SOMORJAI, O. STRANIERO, F. STRIEDER, H. P. TRAUTVETTER, TERRASI, Filippo, D., Bemmerer, F., Confortola, H., Costantini, A., Formicola, G., Gyu, Rky, R., Bonetti, C., Broggini, P., Corvisiero, Z., Eleke, Z., Fu, Lop, G., Gervino, A., Guglielmetti, C., Gustavino, G., Imbriani, M., Junker, M., Laubenstein, A., Lemut, B., Limata, V., Lozza, M., Marta, R., Menegazzo, P., Prati, V., Roca, C., Rolf, C., ROSSI ALVAREZ, E., Somorjai, O., Straniero, F., Strieder, Terrasi, Filippo, and H. P., Trautvetter

Published
2006

30. Study of beam heating effects in a gas target through Rutherford scattering

Author

M. MARTA, F. CONFORTOLA, D. BEMMERER, C. BOIANO, R. BONETTI, C. BROGGINI, M. CASANOVA, P. CORVISIERO, H. COSTANTINI, Z. ELEKES, A. FORMICOLA, Z. FULOP, G. GERVINO, A. GUGLIELMETTI, C. GUSTAVINO, G. GYURKY, G. IMBRIANI, M. JUNKER, A. LEMUT, B. LIMATA, R. MENEGAZZO, P. PRATI, V. ROCA, C. ROLFS, M. ROMANO, C. ROSSI ALVAREZ, E. SOMORJAI, F. STRIEDER, H. P. TRAUTVETTER, TERRASI, Filippo, M., Marta, F., Confortola, D., Bemmerer, C., Boiano, R., Bonetti, C., Broggini, M., Casanova, P., Corvisiero, H., Costantini, Z., Eleke, A., Formicola, Z., Fulop, G., Gervino, A., Guglielmetti, C., Gustavino, G., Gyurky, G., Imbriani, M., Junker, A., Lemut, B., Limata, R., Menegazzo, P., Prati, V., Roca, C., Rolf, M., Romano, C., ROSSI ALVAREZ, E., Somorjai, F., Strieder, Terrasi, Filippo, and H. P., Trautvetter

Published
2006

31. Recent results of the 14N(p,g)measurement at LUNA

Author

H. COSTANTINI, C. ANGULO, D. BEMMERER, R. BONETTI, C. BROGGINI, F. CONFORTOLA, P. CORVISIERO, J. CRUZ, A. FORMICOLA, Z. FÜLÖP, G. GERVINO, A. GUGLIELMETTI, C. GUSTAVINO, G. GYÜRKY, G. IMBRIANI, A. P. JESUS, M. JUNKER, B. LIMATA, R. MENEGAZZO, P. PRATI, V. ROCA, C. ROLFS, M. ROMANO, C. ROSSI ALVAREZ, F. SCHÜMANN, E. SOMORJAI, O. STRANIERO, F. STRIEDER, H. P. TRAUTVETTER, TERRASI, Filippo, H., Costantini, C., Angulo, D., Bemmerer, R., Bonetti, C., Broggini, F., Confortola, P., Corvisiero, J., Cruz, A., Formicola, Z., Fülöp, G., Gervino, A., Guglielmetti, C., Gustavino, G., Gyürky, G., Imbriani, A. P., Jesu, M., Junker, B., Limata, R., Menegazzo, P., Prati, V., Roca, C., Rolf, M., Romano, C., ROSSI ALVAREZ, F., Schümann, E., Somorjai, O., Straniero, F., Strieder, Terrasi, Filippo, and H. P., Trautvetter

Published
2005

32. The LUNA II 400 kV accelerator

Author

A. FORMICOLA, G. IMBRIANI, M. JUNKER, D. BEMMERER, R. BONETTI, C. BROGGINI, C. CASELLA, P. CORVISIERO, H. COSTANTINI, G. GERVINO, C. GUSTAVINO, A. LEMUT, P. PRATI, V. ROCA, C. ROLFS, M. ROMANO, D. SCHURMANN, F. STRIEDER, H. P. TRAUTVETTER, S. ZAVATARELLI, TERRASI, Filippo, A., Formicola, G., Imbriani, M., Junker, D., Bemmerer, R., Bonetti, C., Broggini, C., Casella, P., Corvisiero, H., Costantini, G., Gervino, C., Gustavino, A., Lemut, P., Prati, V., Roca, C., Rolf, M., Romano, D., Schurmann, F., Strieder, Terrasi, Filippo, H. P., Trautvetter, and S., Zavatarelli

Published
2003

33. R-matrix analysis of16O compound nucleus reactions

Author

Richard deBoer, Michael Wiescher, Ethan Uberseder, Joachim Görres, P. J. LeBlanc, and G. Imbriani

Subjects
Physics, Nuclear and High Energy Physics, medicine.anatomical_structure, Radiative capture, medicine, Physical chemistry, Nucleus, R-matrix
Published
2013
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35. A new measuremets of the E1 amplitude in the 12C(alfa,gamma)16O reaction'

Author

L. GIALANELLA, M. ALIOTTA, U. GREIFE, D. ROGALLA, C. ROLFS, F. SCHUEMANN F. STRIEDER, S. THEIS, H. P. TRAUTVETTER, L. CAMPAJOLA, G. IMBRIANI V. ROCA, A. D'ONOFRIO, C. SABBARESE, F. TERRASI, C. AGODI, R. ALBA, A. DEL ZOPPO, P. FIGURA, P. SAPIENZA, C. SPITALERI, G. GYURKY, E. SOMORJAI, ROMANO, MARIO, L., Gialanella, M., Aliotta, U., Greife, D., Rogalla, C., Rolf, F. SCHUEMANN F., Strieder, S., Thei, H. P., Trautvetter, L., Campajola, G. IMBRIANI V., Roca, Romano, Mario, A., D'Onofrio, C., Sabbarese, F., Terrasi, C., Agodi, R., Alba, A., DEL ZOPPO, P., Figura, P., Sapienza, C., Spitaleri, G., Gyurky, and E., Somorjai

Published
2001

37. A new measurement of the E1 amplitude in 12C(α,γ)16O. Nuclear Physics A688(2001)254

Author

GIALANELLA, Lucio, M. ALIOTTA, D. ROGALLA, C. ROLFS, F. SCHUMANN, F. STRIEDER, S. THEIS, H. P. TRAUTVETTER, L. CAMPAJOLA, G. IMBRIANI, V. ROCA, M. ROMANO, D'ONOFRIO, Antonio, SABBARESE, Carlo, C. AGODI, R. ALBA, A. DEL ZOPPO, P. FIGUERA, P. SAPIENZA, C. SPITALERI, G. GYURKY, E. SOMORJAI, U. GREIFE, TERRASI, Filippo, Gialanella, Lucio, M., Aliotta, D., Rogalla, C., Rolf, F., Schumann, F., Strieder, S., Thei, H. P., Trautvetter, L., Campajola, G., Imbriani, V., Roca, M., Romano, D'Onofrio, Antonio, Sabbarese, Carlo, Terrasi, Filippo, C., Agodi, R., Alba, A., DEL ZOPPO, P., Figuera, P., Sapienza, C., Spitaleri, G., Gyurky, E., Somorjai, and U., Greife

Published
2001

38. Proton capture on 17O and its astrophysical implications

Author

Manoel Couder, Ethan Uberseder, Joachim Görres, D. Schürmann, Q. Li, Edward Stech, G. Imbriani, Donald Robertson, A. Best, Richard deBoer, A. Kontos, Michael Wiescher, A., Konto, J., Görre, Best, Andrea, M., Couder, R., Deboer, Imbriani, Gianluca, Q., Li, D., Robertson, D., Schürmann, E., Stech, E., Uberseder, and M., Wiescher

Subjects
Physics, Experimental Nuclear Physic, Nuclear and High Energy Physics, Work (thermodynamics), Range (particle radiation), Proton, 010308 nuclear & particles physics, Resonance, FOS: Physical sciences, 7. Clean energy, 01 natural sciences, Lower energy, Nuclear physics, Reaction rate, Cross section (physics), 13. Climate action, Nucleosynthesis, 0103 physical sciences, Shell Hydrogen burning in stars, Nuclear Experiment (nucl-ex), 010306 general physics, Nuclear Astrophysic, Nuclear Experiment
Abstract

The reaction $^{17}$O$(p,\gamma)^{18}$F influences hydrogen-burning nucleosynthesis in several stellar sites, such as red giants, asymptotic giant branch (AGB) stars, massive stars and classical novae. In the relevant temperature range for these environments ($T_{9}=0.01-0.4), the main contributions to the rate of this reaction are the direct capture process, two low lying narrow resonances ($E_{r}=65.1$ and 183 keV) and the low-energy tails of two broad resonances ($E_{r}=557$ and 677 keV). Previous measurements and calculations give contradictory results for the direct capture contribution which in turn increases the uncertainty of the reaction rate. In addition, very few published cross section data exist for the high energy region that might affect the interpretation of the direct capture and the contributions of the broad resonances in the lower energy range. This work aims to address these issues. The reaction cross section was measured in a wide proton energy range ($E_{c.m.}=345$ - 1700 keV) and at several angles ($\theta_{lab}=0^{\circ},45^{\circ},90^{\circ},135^{\circ}$). The observed primary $\gamma$-transitions were used as input in an $R$-matrix code in order to obtain the contribution of the direct capture and the two broad resonances to the low-energy region. The extrapolated S-factor from the present data is in good agreement with the existing literature data in the low-energy region. A new reaction rate was calculated from the combined results of this work and literature S-factor determinations. Resonance strengths and branchings are reported for several $^{18}$F states. We were able to extrapolate the astrophysical S-factor of the reaction $^{17}$O$(p,\gamma)^{18}$F at low energies from cross section data taken at higher energies. No significant changes in the nucleosynthesis are expected from the newly calculated reaction rate., Comment: Accepted in Physical Review C

Published
2012

39. Elastic scattering of protons from 15N

Author

Ethan Uberseder, P. J. LeBlanc, Michael Wiescher, S. O'Brien, S. Falahat, Richard deBoer, G. Imbriani, Joachim Görres, R., Deboer, P., Leblanc, S., Falahat, Imbriani, Gianluca, J., Görre, S., O’Brien, E., Uberseder, and M., Wiescher

Subjects
Elastic scattering, Physics, Nuclear and High Energy Physics, Proton, Order (ring theory), Nuclear reaction, CNO cycle, Excited state, Yield ratio, Atomic physics, Experimental nuclear physic, Energy (signal processing), Excitation, Spin-½
Abstract

Background: Resonances observed through elastic scattering of protons on ${}^{15}$N can provide information about the partial widths, spin parities, and energies of excited states in ${}^{16}$O near the proton separation energy. This is the same energy region important for the nuclear astrophysics reactions ${}^{15}$N${(p,\ensuremath{\gamma})}^{16}$O and ${}^{15}$N${(p,\ensuremath{\alpha})}^{12}$C. While previous measurements have been made, they are limited in scope, especially in their angular coverage. Purpose: Obtain additional ${}^{15}$N${(p,p)}^{15}$N reaction data which can be used in a global multiple-channel $R$-matrix analysis of the ${}^{16}$O compound nucleus in order to better constrain the level parameters of states which contribute to the reaction ${}^{15}$N${(p,\ensuremath{\gamma})}^{16}$O. Methods: Measure the excitation functions of ${}^{15}$N${(p,p)}^{15}$N over an energy range from ${E}_{p}$ $=$ 0.6 to 1.8 MeV at laboratory angles of 90${}^{\ensuremath{\circ}}$, 105${}^{\ensuremath{\circ}}$, 135${}^{\ensuremath{\circ}}$, 150${}^{\ensuremath{\circ}}$, and 165${}^{\ensuremath{\circ}}$. The reaction ${}^{15}$N${(p,{\ensuremath{\alpha}}_{0})}^{12}$C was measured concurrently. Results: Ratios of the excitation functions were extracted from the yield data. Resonances were identified in the yield ratio data which correspond to previously reported levels in ${}^{16}$O. An $R$-matrix analysis, which fits the present data as well as previous measurements from the literature simultaneously, finds reasonable agreement between the current measurements and those in the literature. Conclusions: The additional data from this measurement will be combined with previous literature data in a comprehensive $R$-matrix analysis of reactions which populate ${}^{16}$O over a similar energy region.

Published
2012

40. Constraining theSfactor ofN15(p,γ)O16at astrophysical energies

Author

A. Guglielmetti, E. Somorjai, C. Mazzocchi, Q. Li, Mary Beard, Antonio Caciolli, Manoel Couder, Daniel Bemmerer, H. Costantini, C. Gustavino, M. Junker, S. O'Brien, Michael Wiescher, Carlo Broggini, R. Menegazzo, R. E. Azuma, Richard deBoer, Vincenzo Roca, A. Lemut, R. Kuntz, A. Formicola, S. Falahat, Joachim Görres, M. Marta, G. Imbriani, A. Kontos, F. Käppeler, H. P. Trautvetter, B. Limata, Frank Strieder, Edward Stech, P. J. LeBlanc, Zs. Fülöp, C. Rolfs, Oscar Straniero, A. Best, Filippo Terrasi, A. Palumbo, Paolo Prati, Gy. Gyürky, H. Leiste, Z. Elekes, P. Corvisiero, Wanpeng Tan, Ethan Uberseder, G. Gervino, and C. Rossi Alvarez

Subjects
Physics, Nuclear reaction, Nuclear and High Energy Physics, CNO cycle, 010308 nuclear & particles physics, S-factor, Gamma ray, 7. Clean energy, 01 natural sciences, 0103 physical sciences, Atomic physics, 010306 general physics, Ground state, Energy (signal processing), Radioactive decay, Oxygen-16
Abstract

The {sup 15}N(p,{gamma}){sup 16}O reaction represents a breakout reaction linking the first and second cycles of the CNO cycles redistributing the carbon and nitrogen abundances into the oxygen range. The reaction is dominated by two broad resonances, at E{sub p}=338 and 1028 keV, and a direct capture contribution to the ground state of {sup 16}O. Interference effects between these contributions both in the low-energy region (E{sub p}

Published
2010
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41. CNO hydrogen burning studied deep underground

Author

D. Bemmerer, F. Confortola, A. Lemut, R. Bonetti, C. Broggini, P. Corvisiero, H. Costantini, J. Cruz, A. Formicola, Zs. Fülöp, G. Gervino, A. Guglielmetti, C. Gustavino, Gy. Gyürky, G. Imbriani, A. P. Jesus, M. Junker, B. Limata, R. Menegazzo, P. Prati, V. Roca, D. Rogalla, C. Rolfs, M. Romano, C. Rossi Alvarez, F. Schümann, E. Somorjai, O. Straniero, F. Strieder, F. Terrasi, and H. P. Trautvetter

Published
2010
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42. Towards a high-precision measurement of the 3He(α, γ)7Be cross section at LUNA

Author

H. Costantini, D. Bemmerer, P. Bezzon, R. Bonetti, C. Broggini, M. L. Casanova, F. Confortola, P. Corvisiero, J. Cruz, Z. Elekes, A. Formicola, Zs. Fülop, G. Gervino, C. Gustavino, A. Guglielmetti, Gy. Gyürky, G. Imbriani, A. P. Jesus, M. Junker, A. Lemut, M. Marta, R. Menegazzo, P. Prati, E. Roc, C. Rolfs, M. Romano, C. Rossi Alvarez, F. Schümann, E. Somorjai, O. Straniero, F. Strieder, F. Terrasi, and H. P. Trautvetter

Published
2010
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43. Stellar and primordial nucleosynthesis of 7Be: measurement of 3He(alpha,gamma)7Be

Author

A, Di Leva, L, Gialanella, R, Kunz, D, Rogalla, D, Schürmann, F, Strieder, M, De Cesare, N, De Cesare, A, D'Onofrio, Z, Fülöp, G, Gyürky, G, Imbriani, G, Mangano, A, Ordine, V, Roca, C, Rolfs, M, Romano, E, Somorjai, and F, Terrasi

Abstract

The 3He(alpha,gamma)7Be reaction presently represents the largest nuclear uncertainty in the predicted solar neutrino flux and has important implications on the big bang nucleosynthesis, i.e., the production of primordial 7Li. We present here the results of an experiment using the recoil separator ERNA (European Recoil separator for Nuclear Astrophysics) to detect directly the 7Be ejectiles. In addition, off-beam activation and coincidence gamma-ray measurements were performed at selected energies. At energies above 1 MeV a large discrepancy compared to previous results is observed both in the absolute value and in the energy dependence of the cross section. Based on the available data and models, a robust estimate of the cross section at the astrophysical relevant energies is proposed.

Published
2008

45. Deep blue emitting ZnS/ZnSe multiple quantum well lasers grown by MOVPE on (001)GaAs

Author

C. Zanotti-Fregonara, Filippo Romanato, Lucio Calcagnile, Giancarlo Salviati, A. V. Drigo, M. Mazzer, Anna Maria Mancini, Paola Prete, Nico Lovergine, G. Imbriani, R. Cingolani, Gabriella Leo, M., Mazzer, L., Calcagnile, G., Leo, G., Salviati, C., Zanotti Fregonara, Lovergine, Nicola, Prete, Paola, G., Imbriani, Cingolani, Roberto, Mancini, Anna Maria, F., Romanato, and Drigo, Antonio

Subjects
Materials science, lasing, business.industry, Mechanical Engineering, Condensed Matter Physics, Laser, ZnS/ZnSe multiple quantum well, Active layer, law.invention, Mechanics of Materials, law, luminescence, Optoelectronics, General Materials Science, Metalorganic vapour phase epitaxy, Stimulated emission, Blue emitting laser, Luminescence, business, Layer (electronics), Quantum well, MOVPE growth, Molecular beam epitaxy
Abstract

The optimisation of ZnSe/ZnS multi-quantum-wells grown by metal-organic vapour phase epitaxy (MOVPE) for lasers was carried out with the help of structural and electro-optical characterisation techniques. Good-quality quantum wells were obtained using a lower growth temperature (315 °C) with respect to the ZnS buffer layer (342 °C). Although even the best samples contain a high density of microtwins crossing the active layer, the luminescence efficiency is quite good and the threshold for the stimulated emission at 10 K is as low as 170 kW cm −2 .

Published
1997

46. Enhanced d(d,p)t fusion reaction in metals

Author

F. Raiola, B. Burchard, Zs. Fülöp, Gy. Gyürky, S. Zeng, J. Cruz, A. Di Leva, B. Limata, M. Fonseca, H. Luis, M. Aliotta, H. W. Becker, C. Broggini, A. D’Onofrio, L. Gialanella, G. Imbriani, A. P. Jesus, M. Junker, J. P. Ribeiro, V. Roca, C. Rolfs, M. Romano, E. Somorjai, F. Strieder, and F. Terrasi

Published
2006
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47. Recent results at LUNA, using a solid target

Author

G. Imbriani, A. Formicola, and H. Costantini

Subjects
Nuclear physics, Physics, Range (particle radiation), CNO cycle, Solar neutrino, Globular cluster, Radiative capture, Extrapolation, High Energy Physics::Experiment, Nuclear Experiment, Radioactive decay, R-matrix
Abstract

The determination of the astrophysical S‐factor of the 14N(p,γ)15O reaction is of great interest because this reaction represents the bottleneck of the CNO cycle, which in turn has a large influence on the determination of the age of globular clusters and also plays a role in the estimation of the Solar neutrino fluxes. We have performed a new underground measurement (LUNA, Gran Sasso Laboratory, Italy) using a high resolution set‐up, extending the investigated energy range down to Ecm=130 keV. This allowed a more reliable extrapolation to astrophysical energies, using an R‐matrix fit to the decay to different final states in 15O.

Published
2006
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48. Change of the 7Be electron capture half-life in metallic environments

Author

B. WANG, S. YAN, B. LIMATA, F. RAIOLA, M. ALIOTTA, H. W. BECKER, J. CRUZ, N. DE CESARE, D'ONOFRIO, Antonio, Z. FU, LO, P, L. GIALANELLA, G. GYU, RKY, G. IMBRIANI, A. JESUS, J. P. RIBEIRO, V. ROCA, D. ROGALLA, C. ROLFS, M. ROMANO, D. SCHU, RMANN, E. SOMORJAI, F. STRIEDER, TERRASI, Filippo, Wang, B., Yan, S., Limata, B., Raiola, F., Aliotta, M., Becker, H. W., Cruz, J., DE CESARE, N., D'Onofrio, Antonio, Fu, Z., Lo, P, Gialanella, L., Gyu, G., Rky, Imbriani, G., Jesus, A., Ribeiro, J. P., Roca, V., Rogalla, D., Rolfs, C., Romano, M., Schu, D., Rmann, Somorjai, E., Strieder, F., and Terrasi, Filippo

Published
2006

50. First direct measurement of the total cross-section of C-12(alpha,gamma)O-16

Author

D. SCHURMANN, A. DILEVA, L. GIALANELLA, D. ROGALLA, F. STRIEDER, N. DECESARE, A, D'ONOFRIO, G. IMBRIANI, R. KUNZ, LUBRITTO, Carmine, A. ORDINE, V. ROCA, C. ROLFS, M. ROMANO, F. SCHUMANN, H. P. TRAUTVETTER, TERRASI, Filippo, Schurmann, D., Dileva, A., Gialanella, L., Rogalla, D., Strieder, F., Decesare, N., D'Onofrio, A, Imbriani, G., Kunz, R., Lubritto, Carmine, Ordine, A., Roca, V., Rolfs, C., Romano, M., Schumann, F., Terrasi, Filippo, and Trautvetter, H. P.

Abstract

The total cross-section of 12C(α,γ)16O was measured for the first time by a direct and ungated detection of the 16O recoils. This measurement in inverse kinematics using the recoil mass separator ERNA in combination with a windowless He gas target allowed to collect data with high precision in the energy range E = 1.9 to 4.9 MeV. The data represent new information for the determination of the astrophysical S(E) factor.

Published
2005

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