D. Shapira*
Physics Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.
Recibido el 10 de marzo de 2010
Aceptado el 31 de agosto de 2010
Abstract
]]> One of the stated goals for proposed and existing facilities that produce and accelerate radioactive ion beams is to explore and achieve a new understanding of the reactions mechanisms leading to the synthesis of the heaviest nuclei. Nuclear synthesis of two large nuclei into a single entity is a complex multistep process. The beam intensities of radioactive ions accelerated at present day facilities are not sufficient to synthesize super heavy elements. However the study of the iso–spin dependence of nuclear synthesis and the many processes competing with it can be carried out at present day facilities. Of special interest are cases where the interacting nuclei and the synthesized product are extremely neutron–rich. The effects of neutron excess on the reaction processes leading to the formation of the synthesized nucleus that emerged in earlier studies are poorly understood and sometimes counter intuitive. Results from measurements performed at HRIBF, as well as our plans for future measurements and the equipment being prepared will be presented.Keywords: Fusion reactions; superheavy synthesis; radioactive ion beams.
Resumen
Uno de los objetivos declarados de los laboratorios que producen y haces acelerados de iones radioactivos es el de explorar y obtener un Nuevo entendimiento de los mecanismos de reacción que conducen a la síntesis de núcleos más pesados. La fusión de dos núcleos pesados en una sola entidad es un proceso complejo de varios pasos. Las intensidades de los haces radioactivos acelerados actualmente no son suficientes para sintetizar elementos superpesados. Sin embargo, el estudio de la dependencia de isoespín de esta síntesis nuclear y los muchos procesos que compiten puede llevarse a cabo con los haces existentes. De interés especial son los casos donde los núcleos en interacción y los productos sintetizados son extremadamente ricos en neutrones. Los efectos del exceso de neutrones en los mecanismos de reaccion involucrados en la síntesis de nuevos núcleos, continúan siendo pobremente entendidos, e incluso llegan a ser contra intuitivos. Aquí presentamos resultados de medidas llevadas a cabo en HRIBF, así como nuestros planes para medidas futuras y el equipo que para ese efecto se esta preparando.
Descriptores: Reacciones de fusión; síntesis de núcleos superpesados; haces de iones radioactivos.
PACS: 25.70.Jj; 24.60.Dr; 25.60.Pj
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]]>References
1. D. Stracener, NIMA 521 (2004) 126. [ Links ]
2. J.J. Cowan et. al., Phys. Rep. C 208 (1991) 267. [ Links ]
3. W. Loveland, Phys. Rev. C 76 (2007) 014612. [ Links ]
4. Yu. Ts. Oganessian et al., Phys. Rev. C 69 (2004) 054608; [ Links ] S. Hoffman et al., Nucl. Phys. News 72 (2004) 733. [ Links ]
5. S. Bjornholm and W.J. Swiatecki, Nucl. Phys. A 391 (1982) 471. [ Links ]
6. C. C. Sahm et al., Nucl. Phys. A 441 (1985) 316; [ Links ] Z. Phys. A 319 (1984)113. [ Links ]
7. A.M. Vinodkumar et al., Phys. Rev. C74 (2006) 064612; [ Links ] Phys. Rev. C 78 (2008) 054608. [ Links ]
8. G. Fazio et al., Phys. Rev. C 72 (2005) 064614. [ Links ]
9. D. Shapira et al., NIMA 551 (2005) 330. [ Links ]
10. "Tracking fission–like products from collisions with radioactive heavy ion beams" A proposal submitted in response to the DOE Research Program Announcement LAB 08–10, "Research Opportunities at Rare Isotope Beam Facilities." D. Shapira, J.F. Liang, C.J. Gross, R.L. Varner, ORNL Physics Division. E. Chavez–Lomeli, UNAM Institute of Physics. W. Loveland, Chemistry Dept. Oregon State Univ. J.J. Kolata, UND Dept of Physics and Astronomy. A.L. Caraley, Dept of Physics, SUNY, Oswego. [ Links ]
11. NSCL TPC workshop Dec. 6 (2007). Presentation available on the web at http://www.nscl.msu.edu/~bickley/TPCWorkshop/ [ Links ]
*. This manuscript has been authored by UT–Battelle, LLC, under Contract No. DE–AC05–00OR22725 with the U.S. Department of Energy's Office of Nuclear Physics. The United States Government retains and the publisher, by accepting the article for publication, acknowledges that the United States Government retains a non–exclusive, paid–up, irrevocable, worldwide license to publish or reproduce the published form of this manuscript, or allow others to do so, for United States Government purposes.
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