Physics papers for your reading pleasure
Papers available for FTP
Jet -- clump interactions in quasars: Proceedings of the 4th International
Symposium Nuclei in the Cosmos, June 1996, Notre Dame/IN, USA, Eds.
J. Görres, G. Matthews, S. Shore and M. Wiescher,
Nucl. Phys. A 621 (1997) 584c-588c
Authors: J. Vandegriff(1), R.N. Boyd(1,2), G. Raimann(1), P. Osmer(2)
(1) Department of Physics, The Ohio State University, Columbus, OH 43210, USA
(2) Department of Astronomy, The Ohio State University, Columbus, OH 43210, USA
Some high redshift quasars (z~4) show strong emission lines for C,
N, and O, indicating high abundances of these elements. In this context,
we have explored the nucleosynthesis that would occur between a high energy
particle jet emanating from an Active Galactic Nucleus (AGN) and nearby
gas. CNO production proceeds through nuclides which result from collisions
between the jet and the gas. Final abundances of the CNO nuclides vary
widely over the densities studied, but reach and even exceed solar levels
for some combinations of temperature, density, and jet intensity and
duration.
The rp-process and new measurements of beta-delayed proton decay
of light Ag and Cd isotopes: Proceedings of the 4th International Symposium
Nuclei in the Cosmos, June 1996, Notre Dame/IN, USA, Eds.
J. Görres, G. Matthews, S. Shore and M. Wiescher,
Nucl. Phys. A 621 (1997) 215c-218c
Authors: G. Raimann(1), M.J. Balbes(1), R.N. Boyd(1,2), D. Cano-Ott(3),
R. Collatz(4), A. Guglielmetti(4), M. Hellström(4), M. Hencheck(5),
Z. Hu(4), Z. Janas(6), M. Karny(6), R. Kirchner(4), J. Morford(5),
D.J. Morrissey(7), E. Roeckl(4), K. Schmidt(4), J. Szerypo(6), A. Weber(4)
(1) Department of Physics, The Ohio State University, Columbus, OH 43210, USA
(2) Department of Astronomy, The Ohio State University, Columbus, OH 43210, USA
(3) Instituto de Fisica Corpuscular, 46100 Burjassot Valencia, Spain
(4) Gesellschaft für Schwerionenforschung, D-64291 Darmstadt, Germany
(5) School of Math & Science, Chadron State College, Chadron, NE 69337, USA
(6) Department of Physics, University of Warsaw, PL-00681 Warsaw, Poland
(7) Department of Chemistry, Michigan State University, East Lansing, MI 48824, USA
Recent network calculations suggest that a high temperature rp-process could
explain the abundances of light Mo and Ru isotopes, which have long challenged
models of p-process nuclide production. Important ingredients to network
calculations involving unstable nuclei near and at the proton drip line are
beta-halflives and decay modes, i.e., whether or not beta-delayed proton
decay takes place. Of particular importance to these network calculation are
the proton-rich isotopes 96Ag, 98Ag, 96Cd and 98Cd. We
report on recent measurements of beta-delayed proton branching ratios for
96Ag, 98Ag, and 98Cd at the on-line mass separator at GSI.
Authors: M. Hellström(1), Z. Hu(1), A. Weber(1), M. Hencheck(2),
M.J. Balbes(3), R.N. Boyd(3), D. Cano-Ott(4), R. Collatz(1), A. Guglielmetti(1),
Z. Janas(5), M. Karny(5), R. Kirchner(1), J. Morford(2), D.J. Morrissey(6),
G. Raimann(3), E. Roeckl(1), K. Schmidt(1), J. Szerypo(5)
(1) Gesellschaft für Schwerionenforschung, D-64291 Darmstadt, Germany
(2) School of Math & Science, Chadron State College, Chadron, NE 69337, USA
(3) Department of Physics, The Ohio State University, Columbus, OH 43210, USA
(4) Instituto de Fisica Corpuscular, 46100 Burjassot Valencia, Spain
(5) Department of Physics, University of Warsaw, PL-00681 Warsaw, Poland
(6) Department of Chemistry, Michigan State University, East Lansing, MI 48824, USA
Detailed information on the decay modes of very proton-rich heavy nuclei is a
prerequisite for p-process nucleosynthesis models. We have therefore measured
beta-delayed protons and gamma-rays from mass-separated sources of 96Ag, 98Ag
and 98Cd, and obtained beta-p branching ratios of 3.7(9)E-02, 1.1(+0.5-0.4)E-05
and .lt. 2.5E-04, respectively. The consequences of the experimental data for
rp-process calculations and the results from a statistical model are briefly
discussed.
Authors: T. Rauscher(1), G. Raimann(2)
(1) Institut fur theoretische Physik, Universitat Basel, Switzerland
(2) Department of Physics, The Ohio State University, Columbus, OH 43210, USA
The reactions 10B(p,alpha)7Be and 11B(p,alpha)8Be are studied at thermonuclear
energies using DWBA calculations. For both reactions, transitions to the ground
states and first excited states are investigated. In the case of
10B(p,alpha)7Be, a resonance at E_Res = 10 keV can be consistently described in
the potential model, thereby allowing the extension of the astrophysical
S-factor data to very low energies. Strong interference with a resonance at
about E_Res = 550 keV require a Breit-Wigner description of that resonance and
the introduction of an interference term for the reaction 10B(p,alpha_1)7Be*.
Two isospin T = 1 resonances (at E_Res1 = 149 keV and E_Res2 = 619 keV)
observed in the 11B + p reactions necessitate Breit-Wigner resonance and
interference terms to fit the data of the 11B(p,alpha)8Be reaction. S-factors
and thermonuclear reaction rates are given for each reaction. The present
calculation is the first consistent parametrization for the transition to the
ground states and first excited states at low energies.
Authors: M.J. Balbes(1), R.N. Boyd(2), G. Steigman(2),
and D. Thomas
(1)Trionix Research Laboratory, Inc., 8037 Bavaria Rd., Twinsburg, OH
44087(Formerly at Department of Physics, The Ohio State University,
Columbus, OH 43210)
(2)Department of Physics, The Ohio State University, Columbus, OH 43210
(Also Department of Astronomy, Ohio State University, Columbus, OH 43210)
This paper explores the Gnedin-Ostriker suggestion that a post-Big-Bang
photodissociation process may modify the primordial abundances of the light
elements. We consider several specific models and discuss the general features
that are necessary (but not necessarily sufficient) to make the model work. We
find that with any significant processing, the final D and 3He abundances,
which are independent of their initial standard big bang nucleosynthesis (SBBN)
values, rise quickly to a level several orders of magnitude above the
observationally inferred primordial values. Solutions for specific models show
that the only initial abundances that can be photoprocessed into agreement with
observations are those that undergo virtually no processing and are already in
agreement with observation. Thus it is unlikely that this model can work for
any non-trivial case unless an artificial density and/or photon distribution is
invoked.
Authors: J. Vandegriff(1), G. Raimann(1), R.N. Boyd(1,2),
M. Caffee(3), B. Ruiz(3)
(1) Department of Physics, The Ohio State University,
Columbus, OH 43210, USA
(2) Department of Astronomy, The Ohio State University,
Columbus, OH 43210, USA
(3) Lawrence Livermore National Laboratory,
Livermore, CA 94550, USA
A search for stable strange quark nuggets has been conducted in helium and
argon using a high sensitivity mass spectrometer. The search was guided by a
mass formula for strange quark nuggets which suggested that stable strange
helium might exist at a mass around 65 u. The chemical similarity of such
``strangelets'' to noble gas atoms and the gravitational unboundedness of
normal helium result in a large enhancement in the sensitivity of such a
search. An abundance limit of no more than 2 x 10^-11 strangelets per normal
nucleus is imposed by our search over a mass region from 42 to 82 u, with much
more stringent limits at most (non-integer) masses.
Authors: G. Raimann(1), A. Ozawa(2), R.N. Boyd(1,3),
F.R. Chloupek(1), M. Fujimaki(2), K. Kimura(4),
T. Kobayashi(2), J.J. Kolata(5), S. Kubono(6),
I. Tanihata(2), Y. Watanabe(2), K. Yoshida(2)
(1) Department of Physics, The Ohio State University,
Columbus, OH 43210, USA
(2) The Institute of Physical and Chemical Research (RIKEN),
Wako-shi, Saitama 351-01, Japan
(3) Department of Astronomy, The Ohio State University,
Columbus, OH 43210, USA
(4) Nagasaki Institute of Applied Science, Nagasaki,
Nagasaki 851-01, Japan
(5) Department of Physics, University of Notre Dame, Notre Dame,
IN 46556, USA
(6) Institute of Nuclear Study, University of Tokyo,
Tanashi, Tokyo 188, Japan
This paper is a study of the beta-delayed neutron decay of 17B using a
radioactive ion beam. The neutron energies, measured via time-of-flight, give
information on states in 17C above the 16C + neutron threshold. States in 17C
were found at excitation energies of 2.25(2) MeV, 2.64(2) MeV and 3.82(5) MeV,
and possibly at 1.18(1) MeV. These low lying states are of possible interest
for nuclear physics as well as for astrophysics.
Papers not available for FTP
Study of the beta-delayed neutron emission of 19C:
Nucl. Phys. A 592 (1995) 244-256
Authors: A. Ozawa, G. Raimann, R.N. Boyd, F.R. Chloupek, M. Fujimaki,
K. Kimura, T. Kobayashi, J.J. Kolata, S. Kubono, I. Tanihata, Y. Watanabe,
K. Yoshida
This paper studies the beta-delayed neutron emission of 19C with the hope of
observing states in 19N close enough to the 18N+n threshold to be of
astrophysical significance. Although transitions to three neutron-unbound
states in 19N have been observed, no states in the energy region of
astrophysical relevance were found. The 19C beta-decay branching ratios to he
observed states have been measured. All states show log(ft) values typical of
allowed transitions. The results are compared with shell-model predictions
carried out in the psd model space.
Identification of new nuclei near the proton drip line:
Phys. Rev. C 50 (1994) 4, 2219-2221
Authors: M. Hencheck, R.N. Boyd, M. Hellström, D.J. Morrisey,
M.J. Balbes, F.R. Chloupek, M. Fauerbach, C.A. Mitchell, R. Pfaff, C.F. Powell,
G. Raimann, B.M. Sherril, M. Steiner, J. Vandegriff, S.J. Yenello
Nine new very neutron-deficient isotopes of Ag, Pd, Rh, and Ru have been
identified among the reaction products of an E/A = 60 MeV 106Cd beam using the
A1200 projectile fragment separator at the National Superconducting Cyclotron
Laboratory. One of these isotopes, 94Ag, is among the heaviest N=Z nuclei
observed so far. The resulting mass spectra are presented and the astrophysical
implications of the stability towards proton emission of one of the new
isotopes, 95Ag, are discussed.
Reaction rates of proton and deuteron induced reactions on lithium:
Z. Phys. A 347 (1993) 73-74
Author: G. Raimann
This paper calculates reaction rates for recently available low-energy data on
7Li(p,alpha)4He, 6Li(p,3He)4He and 6Li(d,alpha)4He and compares them to
literature values. While the new rates are considered to be more accurate,
their absolute magnitude agrees within about 10% with the most recent
compilation.
Created by chloupek@mps.ohio-state.edu
Last modified November 24, 1997 (GR).
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