R. A. Rice

Extended parameterization of nuclear-reaction cross sections for few-nucleon nuclei

We present a series of extended parametric fits to the S-factors and, therefore, the cross sections, for the light-nuclei fusion reactions D(D, p)T, D(D, n)3He, 3He(D, p)4He and T(D, n)4He. These fits constitute a family of continuous functions valid over a very wide range of energies (∼ 0 to ∼50 MeV) that may be used in reaction-rate and other calculations involving these reactions. Thus, they have a much more extended range of applicability compared to previous similar fits.

The Role of Velocity Distribution in Cold Deuterium-Deuterium Fusion

AbstractReaction rates from recent electrochemical fusion experiments have been found to be as many as seventy orders of magnitude larger than those obtained from simple calculations involving an extrapolated low-energy deuterium-deuterium (D-D) cross section and a sharp velocity distribution. However, if an appropriate Maxwell-Boltzmann velocity distribution is used in place of the conventional sharp (mono-energetic) velocity distribution, the calculated reaction rate increases by as much as fifty to sixty orders of magnitude. Furthermore, the center-of-mass energy at which the D-D cross section is evaluated for given D-D energy is much larger than that used in the conventional calculations due to the higher energy components in the Maxwell-Boltzmann distribution. Finally, the above results are not significantly affected if a reasonable high-energy cutoff Ec is included in the velocity distribution.

Conventional nuclear physics solution of the solar neutrino problem

A basic and inherently simple alternative explanation of the solar neutrino problem is proposed based upon conventional nuclear physics. Our results for the tunneling factor, astrophysicalS-factor, and our resolution are compared with rather speculative solutions commonly attempted by accepting the customary ingredients of the standard solar model. We present a more realistic solution of nuclear Coulomb barrier tunneling together with a more precise parametric representation of the astrophysical functionS. We determineS from high-energy (>100 keV)7Be(p, γ)8B experimental cross-section data using the new tunneling factor. This leads to a low-energy fusion cross section that is lower than previous estimates by ∼26–36%, decreasing the anticipated neutrino flux close to experimentally detected values. This may resolve the missing solar neutrino flux problem.

Cluster-impact fusion and effective deuteron temperature.

Temperature and kinematic line broadening are the primary contributions to the width of the proton energy spectrum measured in cluster-impact fusion experiments. By ascertaining these two contributions, we have determined an effective temperature for the high-velocity deuteron component that is responsible for the measured fusion yield. The extracted effective temperature is substantially higher than conventional estimates, and implies that cluster-impact fusion is hot fusion on an atomic scale. The proton spectrum rules out contaminants in explaining the high yield.

THEORIES OF CLUSTER-IMPACT FUSION WITH ATOMIC AND MOLECULAR CLUSTER BEAMS

Apparently disparate experimental results have been obtained for deuterium-deuterium (D-D) fusion products from the impact of atomic and molecular cluster beams on deuterated targets. Unexpectedly high fusion rates observed with beams of D2O clusters in the energy range 10–1000 eV per deuteron have been a formidable challenge to theoretical physics with previous attempts to explain these surprisingly high yields being unsuccessful. A further challenge exists because the resultant models also do not explain why fusion is not observed in similar experiments with beams of D clusters. We present a theory in which heavy atomic partners in the molecule play a vital role in producing the observed rates, and which can also explain the apparently conflicting experimental results.

Cluster-impact fusion with cluster beams

Recent experiments in which beams of D2O clusters impact on deuterated targets have been observed to produce higher than expected deuterium-deuterium (D-D) fusion rates, whereas similar experiments with pure D clusters produced no observable D-D fusion. We present a theoretical model capable of explaining these apparently conflicting experimental results. Our calculations indicate that heavy atoms such as O in the cluster, and Ti, Zr, or C in the target are essential for obtaining high fusion rates and D energy enhancement by double Rutherford backscattering in the experiments as conducted. We predict the conditions for obtaining comparable yields from D, D2O, and H2O clusters and propose a set of experimental tests.

The role of the low-energy proton-deuteron fusion cross section in physical processes

In this paper, the authors calculate the proton-deuterium (p-D) fusion reaction rate at low energies (E {le} 2 keV in the center-of-mass frame) for a Maxwell- Boltzmann velocity distribution and compare it to those for other reactions involving hydrogen isotopes. It is shown that p-D fusion dominates competing reactions for E {le} 8 eV in the center-of-mass frame. The implications for various physical processes are discussed.

Shock-wave impact fusion with cluster beams

Abstract A theoretical model is presented for shock-wave cluster impact fusion that can explain and predict DD fusion rates for D 2 O, H 2 O, and D cluster beams impacting on deuterated targets, e.g. TiD, (C 2 D 4 ) n , and ZrD 1.65 . Two physically reasonable parameters, obtained from one set of data, are used as input in the general theory to provide predictions for different targets and projectiles. This theory in the form of a universal scaling equation explains and reproduces the observed fusion rates as a function of cluster beam composition and energy.

Comments on “Electron Transitions on Deep Dirac Levels I”

In a recent paper, the authors claim the existence of deeply bound electron energy levels in hydrogen-like atoms resulting from previously neglected solutions of both the relativistic Schrodinger and Dirac equations. In this letter, we show that these solutions are unphysical, and thus, these deeply bound energy levels cannot exist. The radial part of the relativistic Schrodinger equation for a point Coulomb potential e<t>(r) = —Ze/r is

Hot plasma shock‐wave theory of cluster‐impact fusion

This paper demonstrates that cluster‐impact fusion can be understood as ‘‘hot fusion’’ on a microscopically small atomic scale. We show that it is improbable to account for the data as an artifact of contamination. By means of theoretical analysis based on a universal scaling equation, our high temperature model is shown to be consistent with the known data of recent deuteron‐deuteron fusion experiments in which clusters of D2O, H2O, and D are accelerated onto deuterated targets. Furthermore, we show that the line broadening of the experimentally obtained proton spectrum supports our prediction of the high temperature in the impact region. Although we have focused on a temperature enhancing shock‐wave model, our methodology and scaling equation are sufficiently general to encompass additional processes such as pinch instability heating. We estimate the present efficiency of this process, and predict higher efficiencies for various experimental conditions.