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Astrophysical($ALPHA$, $GAMMA$) reaction in inverse kinematics; Electron screening effect in the beta-decay
Ujic P., de Oliveira F., Lagoyannis A., Mertzimekis T.J., Harissopulos S. et al
Dans Journal of Physics: Conference Series - Nuclear Physics in Astrophysics V, Eilat : Israël (2011) - http://hal.in2p3.fr/in2p3-00675011
Physique/Physique Nucléaire Expérimentale
Astrophysical($ALPHA$, $GAMMA$) reaction in inverse kinematics; Electron screening effect in the beta-decay
P. Ujic1, F. de Oliveira1, A. Lagoyannis, T.J. Mertzimekis, S. Harissopulos, P. Demetriou, A. Spyrou, C. Stodel1, M.G. Saint-Laurent1, O. Kamalou1, A. Lefebvre-Schuhl2, S. Grevy1, L. Caceres1, M. Lewitowicz1, M.A. Amthor1, L. Perot3, A. Coc2, V. Tatischeff2, J. Kiener2, O. Sorlin1, A. Lepailleur1, M. Assié1, B. Bastin1, N.L. Achouri4, R. Borcea, C. Borcea, M. Stanoiu, G. De France1, E. Clement1, A. Pautrat5, A. Buta, L. Gaudefroy, V. Meot, I. Deloncle2
1 :  GANIL - Grand Accélérateur National d'Ions Lourds
http://www.ganil-spiral2.eu
CNRS : UPR3266 – IN2P3 – CEA : DSM/GANIL
Bvd Henri Becquerel - BP 55027 - 14076 CAEN CEDEX 5
France
2 :  CSNSM - Centre de Spectrométrie Nucléaire et de Spectrométrie de Masse
http://www-csnsm.in2p3.fr/
CNRS : UMR8609 – IN2P3 – Université Paris XI - Paris Sud
batiments 104 et 108 - 91405 Orsay Campus
France
3 :  IPNO - Institut de Physique Nucléaire d'Orsay
http://ipnweb.in2p3.fr
CNRS : UMR8608 – IN2P3 – Université Paris XI - Paris Sud
IPN - 15, rue Georges Clemenceau - 91406 ORSAY CEDEX
France
4 :  LPCC - Laboratoire de Physique Corpusculaire de Caen
http://www.lpc-caen.in2p3.fr/
CNRS : UMR6534 – IN2P3 – Université de Caen Basse-Normandie – Ecole Nationale Supérieure d'Ingénieurs de Caen
ENSICAEN - 6, boulevard du Marechal Juin 14050 Caen Cedex
France
5 :  CRISMAT - Laboratoire de cristallographie et sciences des matériaux
http://www-crismat.ensicaen.fr
CNRS : UMR6508 – Université de Caen Basse-Normandie – Ecole Nationale Supérieure d'Ingénieurs de Caen
6 Bvd du maréchal Juin 14050 CAEN CEDEX 4
France
CSNSM AN
Structure nucléaire
CSNSM SNO
The abundance calculations of the p-nuclei produced in explosive stellar sites rely on the Hauser-Feshbach (HF) theory with the alpha-article optical model potential (α-OMP) one of its major ingredients. To date, most of the (α, γ) cross sections measured show that HF calculations can be wrong by a factor of ten or more especially when phenomenological α-OMP are employed. To investigate the relevant uncertainties entering the HF calculations and furthermore develop global microscopic α-OMPs, systematic (α, γ) cross-section measurements are necessary. This led us to perform a feasibility study of (α, γ) measurements in inverse kinematics that will allow us to employ also radioactive beams in the future. Hence, the 4He(78Kr,γ)82Sr reaction was studied using the LISE3 spectrometer to separate the 82Sr recoils from the primary 78Kr beam. Although an excellent rejection factor > 1010 was achieved, the position of the ions of interest was unexpectedly masked by a secondary beam of high intensity. Given these, new setup improvements are proposed to remove the pollutant ions. Recently, many experiments were conducted in order to study the influence of the environment (especially in a metallic material) on the decay probability of radioactive nuclei. Additionally, hydrogen-like fusion reactions were performed indicating a change in the cross-section due to the influence of the Coulomb field screening induced by quasi-free electrons in metals. This was explained by the Debye screening model which treats metallic electrons within Maxwell-Boltzmann statistics. We measured the decay rate of 19O in metallic, insulating and superconducting environments whereas the electrons in the superconductors should obey the Bose-Einstein statistics. The decay rate measurement was supported by a branching ratios measurement. We found that the effect on the decay rate, if any, is less than the 0.1%, far below the theoretical predictions.

Communications avec actes
2012
2011
Journal of Physics: Conference Series
internationale
337
012015

Nuclear Physics in Astrophysics V
Eilat
Israël
03/04/2011
08/04/2011

GANIL 2012-028 A; CSNSM AN, CSNSM SNO
23.40.-s, 25.75.-q, 21.60.Gx, 27.10.+h, 24.10.Ht, 95.30.Cq
Nuclear physics – Particle physics and field theory – Astrophysics and astroparticles