481 research outputs found
Experience in feeding coal into a liquefaction process development unit
A system for preparing coal slurry and feeding it into a high pressure liquefaction plant is described. The system was developed to provide supporting research and development for the Bureau of Mines coal liquefaction pilot plant. Operating experiences are included
Existence and Uniqueness of Tri-tronqu\'ee Solutions of the second Painlev\'e hierarchy
The first five classical Painlev\'e equations are known to have solutions
described by divergent asymptotic power series near infinity. Here we prove
that such solutions also exist for the infinite hierarchy of equations
associated with the second Painlev\'e equation. Moreover we prove that these
are unique in certain sectors near infinity.Comment: 13 pages, Late
Rational Solutions of the Painleve' VI Equation
In this paper, we classify all values of the parameters , ,
and of the Painlev\'e VI equation such that there are
rational solutions. We give a formula for them up to the birational canonical
transformations and the symmetries of the Painlev\'e VI equation.Comment: 13 pages, 1 Postscript figure Typos fixe
On the Linearization of the First and Second Painleve' Equations
We found Fuchs--Garnier pairs in 3X3 matrices for the first and second
Painleve' equations which are linear in the spectral parameter. As an
application of our pairs for the second Painleve' equation we use the
generalized Laplace transform to derive an invertible integral transformation
relating two its Fuchs--Garnier pairs in 2X2 matrices with different
singularity structures, namely, the pair due to Jimbo and Miwa and the one
found by Harnad, Tracy, and Widom. Together with the certain other
transformations it allows us to relate all known 2X2 matrix Fuchs--Garnier
pairs for the second Painleve' equation with the original Garnier pair.Comment: 17 pages, 2 figure
Temperature measurements of fusion plasmas produced by petawatt laser-irradiated D2-3He or CD4-3He clustering gases
Two different methods have been employed to determine the plasma temperature
in a laser-cluster fusion experiment on the Texas Petawatt laser. In the first,
the temperature was derived from time-of-flight data of deuterium ions ejected
from exploding D2 or CD4 clusters. In the second, the temperature was measured
from the ratio of the rates of two different nuclear fusion reactions occurring
in the plasma at the same time: D(d, 3He)n and 3He(d, p)4He. The temperatures
determined by these two methods agree well, which indicates that: i) The ion
energy distribution is not significantly distorted when ions travel in the
disassembling plasma; ii) The kinetic energy of deuterium ions, especially the
hottest part responsible for nuclear fusion, is well described by a
near-Maxwellian distribution.Comment: 13 pages, 4 figure
Experimental study of fusion neutron and proton yields produced by petawatt-laser-irradiated D2-3He or CD4-3He clustering gases
We report on experiments in which the Texas Petawatt laser irradiated a
mixture of deuterium or deuterated methane clusters and helium-3 gas,
generating three types of nuclear fusion reactions: D(d, 3He)n, D(d, t)p and
3He(d, p)4He. We measured the yields of fusion neutrons and protons from these
reactions and found them to agree with yields based on a simple cylindrical
plasma model using known cross sections and measured plasma parameters. Within
our measurement errors, the fusion products were isotropically distributed.
Plasma temperatures, important for the cross sections, were determined by two
independent methods: (1) deuterium ion time-of-flight, and (2) utilizing the
ratio of neutron yield to proton yield from D(d, 3He)n and 3He(d, p)4He
reactions, respectively. This experiment produced the highest ion temperature
ever achieved with laser-irradiated deuterium clusters.Comment: 16 pages, 6 figure
Measurement of the plasma astrophysical S factor for the 3He(D, p)4He reaction in exploding molecular clusters
The plasma astrophysical S factor for the 3He(D, p)4He fusion reaction was
measured for the first time at temperatures of few keV, using the interaction
of intense ultrafast laser pulses with molecular deuterium clusters mixed with
3He atoms. Different proportions of D2 and 3He or CD4 and 3He were mixed in the
gas jet target in order to allow the measurement of the cross-section for the
3He(D, p)4He reaction. The yield of 14.7 MeV protons from the 3He(D, p)4He
reaction was measured in order to extract the astrophysical S factor at low
energies. Our result is in agreement with other S factor parameterizations
found in the literature
Mass measurements of very neutron-deficient Mo and Tc isotopes and their impact on rp process nucleosynthesis
The masses of ten proton-rich nuclides, including the N=Z+1 nuclides 85-Mo
and 87-Tc, were measured with the Penning trap mass spectrometer SHIPTRAP.
Compared to the Atomic Mass Evaluation 2003 a systematic shift of the mass
surface by up to 1.6 MeV is observed causing significant abundance changes of
the ashes of astrophysical X-ray bursts. Surprisingly low alpha-separation
energies for neutron-deficient Mo and Tc are found, making the formation of a
ZrNb cycle in the rp process possible. Such a cycle would impose an upper
temperature limit for the synthesis of elements beyond Nb in the rp process.Comment: Link to online abstract:
http://link.aps.org/doi/10.1103/PhysRevLett.106.12250
The Hamiltonian Structure of the Second Painleve Hierarchy
In this paper we study the Hamiltonian structure of the second Painleve
hierarchy, an infinite sequence of nonlinear ordinary differential equations
containing PII as its simplest equation. The n-th element of the hierarchy is a
non linear ODE of order 2n in the independent variable depending on n
parameters denoted by and . We introduce new
canonical coordinates and obtain Hamiltonians for the and
evolutions. We give explicit formulae for these Hamiltonians showing that they
are polynomials in our canonical coordinates
Breakup of the proton halo nucleus 8B near barrier energies
The dynamics of a nuclear open quantum system could be revealed in the correlations between the breakup fragments of halo nuclei. The breakup mechanism of a proton halo nuclear system is of particular interest as the Coulomb polarization may play an important role, which, however, remains an open question. Here we use a highly efficient silicon detector array and measure the correlations between the breakup fragments of 8B incident on 120Sn at near-barrier energies. The energy and angular correlations can be explained by a fully quantum mechanical method based on the state-of-the-art continuum discretized coupled channel calculations. The results indicate that, compared to the neutron halo nucleus 6He, 8B presents distinctive reaction dynamics: the dominance of the elastic breakup. This breakup occurs mainly via the short-lived continuum states, almost exhausts the 7Be yield, indicating the effect of Coulomb polarization on the proton halo state. The correlation information reveals that the prompt breakup mechanism dominates, occurring predominantly on the outgoing trajectory. We also show that, as a large environment, the continuum of 8B breakup may not significantly influence elastic scattering and complete fusion.National Key R&D Program of China 2018YFA0404404National Natural Science Foundation of China U2167204, 12175314, 12235020, U18672122Continuous Basic Scientific Research WDJC-2019-13Leading Innovation Project LC192209000701, LC202309000201Basic Scientific Research Program JCKY2020201C002Ministerio de Ciencia e Innovación PID2020-114687GB-I00Junta de Andalucía P20_01247Korea government (MSIT) 2013M7A1A1075764, 2018R1A5A102556
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