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Title: The Interaction of 6He with 197Au and 206Pb

Abstract

Excitation functions have been measured for evaporation residues from compound nuclei formed in the interaction of 6He with 197Au and 206Pb. The transfer reactions leading to 194Au, 196Au and 198Au were also studied for the case of 6He + 197Au. The experiments were performed at the JINR accelerator complex for radioactive beams DRIBs, capable of providing 6He beams of about 10 AMeV maximum energy and an intensity of up to 2x107 pps. The stacked foil activation technique was used directly in the beam extracted from the cyclotron or in the focal plane of the magnetic spectrometer MSP-144. The identification of the reaction products was done by their radioactive {gamma}- or {alpha}-decay. The fusion reactions with the evaporation of two neutrons were characterized by an increase in the cross section compared to statistical model calculations. The analysis of the data in the framework of the statistical model for the decay of excited nuclei when the sequential fusion of 6He was taken into account has shown good agreement between the experimental and the calculated values of the cross sections for the case of sub-Coulomb-barrier fusion in the 206Pb+6He reaction. At the Coulomb barrier unusually high cross section was measured for the productionmore » of 198Au, whereas only an upper limit was determined for the formation of 199Au. Possible mechanisms of formation and decay of transfer reaction products are discussed.« less

Authors:
; ; ; ; ; ;  [1]
  1. Joint Institute for Nuclear Research, 141980 Dubna (Russian Federation)
Publication Date:
OSTI Identifier:
21061838
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 912; Journal Issue: 1; Conference: International symposium on exotic nuclei, Khanty-Mansiysk (Russian Federation), 17-22 Jul 2006; Other Information: DOI: 10.1063/1.2746580; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
73 NUCLEAR PHYSICS AND RADIATION PHYSICS; ALPHA DECAY; COMPOUND NUCLEI; COULOMB FIELD; EXCITATION FUNCTIONS; GOLD 194; GOLD 196; GOLD 197 TARGET; GOLD 198; GOLD 199; HEAVY ION FUSION REACTIONS; HELIUM 6 REACTIONS; JINR; LEAD 206 TARGET; NEUTRONS; RADIOACTIVE ION BEAMS; STATISTICAL MODELS; TRANSFER REACTIONS

Citation Formats

Penionzhkevich, Yu. E., Kalpakchieva, R., Kulko, A. A., Lukyanov, S. M., Maslov, V. A., Skobelev, N. K., and Sobolev, Yu. G. The Interaction of 6He with 197Au and 206Pb. United States: N. p., 2007. Web. doi:10.1063/1.2746580.
Penionzhkevich, Yu. E., Kalpakchieva, R., Kulko, A. A., Lukyanov, S. M., Maslov, V. A., Skobelev, N. K., & Sobolev, Yu. G. The Interaction of 6He with 197Au and 206Pb. United States. doi:10.1063/1.2746580.
Penionzhkevich, Yu. E., Kalpakchieva, R., Kulko, A. A., Lukyanov, S. M., Maslov, V. A., Skobelev, N. K., and Sobolev, Yu. G. Tue . "The Interaction of 6He with 197Au and 206Pb". United States. doi:10.1063/1.2746580.
@article{osti_21061838,
title = {The Interaction of 6He with 197Au and 206Pb},
author = {Penionzhkevich, Yu. E. and Kalpakchieva, R. and Kulko, A. A. and Lukyanov, S. M. and Maslov, V. A. and Skobelev, N. K. and Sobolev, Yu. G.},
abstractNote = {Excitation functions have been measured for evaporation residues from compound nuclei formed in the interaction of 6He with 197Au and 206Pb. The transfer reactions leading to 194Au, 196Au and 198Au were also studied for the case of 6He + 197Au. The experiments were performed at the JINR accelerator complex for radioactive beams DRIBs, capable of providing 6He beams of about 10 AMeV maximum energy and an intensity of up to 2x107 pps. The stacked foil activation technique was used directly in the beam extracted from the cyclotron or in the focal plane of the magnetic spectrometer MSP-144. The identification of the reaction products was done by their radioactive {gamma}- or {alpha}-decay. The fusion reactions with the evaporation of two neutrons were characterized by an increase in the cross section compared to statistical model calculations. The analysis of the data in the framework of the statistical model for the decay of excited nuclei when the sequential fusion of 6He was taken into account has shown good agreement between the experimental and the calculated values of the cross sections for the case of sub-Coulomb-barrier fusion in the 206Pb+6He reaction. At the Coulomb barrier unusually high cross section was measured for the production of 198Au, whereas only an upper limit was determined for the formation of 199Au. Possible mechanisms of formation and decay of transfer reaction products are discussed.},
doi = {10.1063/1.2746580},
journal = {AIP Conference Proceedings},
number = 1,
volume = 912,
place = {United States},
year = {Tue May 22 00:00:00 EDT 2007},
month = {Tue May 22 00:00:00 EDT 2007}
}
  • The properties of the remnant resulting from the emission of prompt particles in the interaction of 1A GeV {sup 197}Au+C interactions have been compared with intranuclear cascade and Boltzmann-Uehling-Uhlenback transport calculations. The number of first-stage particles and the energy spectra of first-stage protons are also compared. Both models can fit the general but not the detailed features of the data. (c) 1999 The American Physical Society.
  • Excitation functions have been measured for the fusion reaction 197Au({alpha}xn)201-xnTl with the evaporation of x neutrons (0{<=}x{<=}3) in the energy range 14-36 MeV. The induced-activation method was used for registration and identification of the reaction products. The experimental cross sections for the (1-3)-neutron evaporation residues are in good agreement with the results known from literature. For the radiation capture reaction 197Au({alpha},{gamma})201Tl, the upper limit was obtained essentially lower. The excitation functions for the measured reactions are compared with calculations in the frame of the statistical model, as well as with formerly measured similar data with a 6He beam.
  • The 4He(6He,2{alpha})2n reaction was studied in experiments designed for the observation of a quasi-free scattering (QFS) occurring between the {alpha} core of the Borromean 6He nuclei and the 4He target nuclei. The helium gas target cooled down to 14 K was bombarded by a 25A MeV secondary beam of 6He nuclei produced at the fragment separator ACCULINNA (Dubna). The data were analyzed with the use of the Plane Wave Impulse Approximation (PWIA) and the three-body wave function of 6He and taking into account the n - n final state interaction. Correlation obtained in the reaction exit channel between the momentummore » values characteristic to the {alpha}-2n and n-n subsystems were found to be consistent with the PWIA predictions. This suggests that QFS could be suitable for the study of other Borromean nuclei.« less
  • We report on the rapidity and centrality dependence of proton and anti-proton transverse mass distributions from {sup 197}Au + {sup 197}Au collisions at {radical}s{sub NN} = 130 GeV as measured by the STAR experiment at RHIC. Our results are from the rapidity and transverse momentum range of |y| < 0.5 and 0.35 < p{sub t} < 1.00 GeV/c. For both protons and anti-protons, transverse mass distributions become more convex from peripheral to central collisions demonstrating characteristics of collective expansion. The measured rapidity distributions and the mean transverse momenta versus rapidity are flat within |y| < 0.5. Comparisons of our datamore » with results from model calculations indicate that in order to obtain a consistent picture of the proton(anti-proton) yields and transverse mass distributions the possibility of pre-hadronic collective expansion may have to be taken into account.« less
  • Initial eccentricity and eccentricity fluctuations of the interaction volume created in relativistic collisions of deformed {sup 197}Au and {sup 238}U nuclei are studied using optical and Monte-Carlo (MC) Glauber simulations. It is found that the non-sphericity noticeably influences the average eccentricity in central collisions and eccentricity fluctuations are enhanced due to deformation. Quantitative results are obtained for Au+Au and U+U collisions at energy {radical}s{sub NN} = 200 GeV.