Ultra low momentum neutron catalyzed nuclear reactions on metallic hydride surfaces

Ultra low momentum neutron catalyzed nuclear reactions in metallic hydride system surfaces are discussed. Weak interaction catalysis initially occurs when neutrons (along with neutrinos) are produced from the protons that capture “heavy” electrons. Surface electron masses are shifted upwards by localized condensed matter electromagnetic fields. Condensed matter quantum electrodynamic processes may also shift the densities of final states, allowing an appreciable production of extremely low momentum neutrons, which are thereby efficiently absorbed by nearby nuclei. No Coulomb barriers exist for the weak interaction neutron production or other resulting catalytic processes. PACS 24.60.-k, 23.20.Nx     

Status of the energy-buncher in the low-energy branch of the Super-FRS

An ion-optical study on the layout of the so-called energy-buncher stage in the low-energy branch of the planned fragment separator Super-FRS is presented. The main purpose of the energy-buncher is a significant reduction of the energy spread of the `hot' fragments at the exit of the separator. Alternatively, the central unit of the buncher—a large dispersive dipole system—can be used as a high-resolution spectrometer for secondary products of nuclear reactions. The proposed design provides a large degree of flexibility for different experimental scenarios with slowed-down low-energy or stopped exotic isotopes.     

Nuclear auger effect in muonic atoms

In a muonic atom electromagnetic transitions proceed via emission of X-rays, electrons from the atomic cloud (Auger electrons), or neutrons from the nucleus (nuclear Auger effect). We calculate the neutron spectrum for muonic ²⁰⁷Pb and ²⁰⁹Bi within a microscopic theory of nuclear reactions. The compound nucleus mechanism is dominant. Most of the neutrons arise from the E2 transition 3d → 1s. Agreement between experiment and calculation is achieved to within a factor of 2.     

Nuclear reactions triggered by laser-accelerated high-energy ions

A technique is suggested for triggering nuclear reactions by accelerating ions with a powerful ultrashort laser pulse in a plasma. The underlying idea of the suggested compact “reactor” is utilization of high-energy ions accelerated by the charge-separation electrostatic field in the direction perpendicular to the laser beam axis in a gas-filled capillary. Accelerated ions with energies of several MeV penetrating the target from the inside surface of a channel give rise to nuclear reactions which can be used to create a compact source of fast neutrons and neutrons of intermediate energies for generating various (short-and long-lived, light and heavy) isotopes, for generating gamma radiation over a broad energy range, for making sources of light ion and induced radioactivity. The yield of the corresponding nuclear reactions as a function of the laser beam parameters has been investigated. The suggested technique for triggering nuclear reactions provides a practical tool for studies of nuclear transformation on the pico-and nanosecond scales, which cannot be achieved using other methods. Zh. éksp. Teor. Fiz. 115, 2080–2090 (June 1999)     

Simulation of interactions of electrons and positrons with matter in MCU-PD code

The Monte Carlo method is used in the MCU code—an application package for solving equations of transport of neutrons, photons, electrons, and positrons. The code has a modular structure, and every working version of the code is formed from modules and submodules depending on the problem in question. The submodules BETA and BEG, included in the SOFIZM compound physical module of the MCU-PD code, are described: BETA submodule simulates interaction of electrons and positrons with matter and BEG submodule generates photons in the electron and positron reactions with matter. The library of constants which is involved in the MCUDB50 database and supports execution of the MCU-PD code is briefly characterized.     

Hard X-ray bursts and DD microfusion neutrons from complex plasmas of vacuum discharge

We create the random complex media of high-power density in low-energy nanosecond vacuum discharges. Hard X-ray emission efficiency, generation of energetic ions (∼1 MeV) and neutrons, trapping and releasing of fast ions and/or X-rays from interelectrode aerosol ensembles are the subject of our study. The neutrons from DD microfusion, as well as the modelling of some interstellar nuclear burning due to microexplosive nucleosynthesis are discussed. The value of neutron yield from DD fusion in interelectrode space varies and amounts to ∼10^{5–10 7}/4π per shot under ≈ 1 J of total energy deposited to create all discharge processes Article presented at the International Conference on the Frontiers of Plasma Physics and Technology, 9–14 December 2002, Bangalore, India.     

Formation and dynamics of relativistic electromagnetic solitons in plasmas containing high-and low-energy electron components

We present theoretical and numerical studies of the nonlinear interactions between intense electromagnetic waves in plasmas containing high-and low-energy electron components. Such plasmas are frequently observed in laser-plasma experiments, where the hot electron component is created by the acceleration of electrons by strong electrostatic waves that are created by the laser-induced Raman forward and backward instabilities. The two-component electron plasma is described by the Vlasov equation for the hot electrons and the hydrodynamic equations for the cold electrons, which are coupled nonlinearly to the electromagnetic wave equation and the Poisson equation for the potential. The present nonlinear system is shown to admit electromagnetic solitary waves correlated with a positive potential and trapped electron islands from the hot electron population. The text was submitted by the authors in English.     

Neutron-, ion-, and electron-energy spectra in a 1 kJ plasma focus

The neutron energy spectrum (4 Torr deuterium) was determined from 30 m flight histograms.—An average energy of approximately 100±20 keV of the neutron producing deuterons within an assumed cone angle of approximately 40 degrees along thez-axis was calculated by means of the target beam model.—Shadow bar techniques reveal that only 10% of the neutrons are produced in the ≈1 cm long focus.—Experimental time of flight analysis confirms that the ion spectrum extends from less than 70 to greater than 400 keV. The electron spectrum in 8 Torr hydrogen follows a ≈3 keV Boltzmann distribution, but demonstrates the presence of nonthermal >100 keV electrons.     

Dynamics of low-energy nuclear forces for electromagnetic and weak reactions with the deuteron in the Nambu-Jona-Lasinio model of light nuclei

A dynamics of low-energy nuclear forces is investigated for low-energy electromagnetic and weak nuclear reactions with the deuteron in the Nambu-Jona-Lasinio model of light nuclei by example of the neutron-proton radiative capture (M1-capture) n + p → D + γ, the photomagnetic disintegration of the deuteron γ + D → n + p and weak reactions of astrophysical interest. These are the solar proton burning p + p → D + e⁺ + ν _e, the pep-process p + e⁻ + p → D + ν _e and the neutrino and antineutrino disintegration of the deuteron caused by charged ν _e + D → e⁻ + p + p, + D → e⁺ + n + n and neutral ν _e() + D → ν _e() + n + p weak currents.     

Is astronomy possible with neutral ultrahigh energy cosmic ray particles existing in the standard model?

The recently observed correlation between HiRes stereo cosmic ray events with energies E ∼ 10¹⁹ eV and BL Lacertae objects occurs at an angle that strongly suggests that the primary particles are neutral. We analyze whether this correlation, if not a statistical fluctuation, can be explained within the Standard Model, i.e., assuming only known particles and interactions. We have not found a plausible process that can account for these correlations. The mechanism that comes closest—the conversion of protons into neutrons in the IR background of our Galaxy—still underproduces the required flux of neutral particles by about two orders of magnitude. The situation is different at E ∼ 10²⁰ eV, where the flux of cosmic rays at the Earth may contain up to a few percent of neutrons, indicating their extragalactic sources. The text was submitted by the authors in English.     

Semi-leptonic weak and electromagnetic interactions in nuclei:: Parity violations in electron scattering and weak neutral currents

A general result for the difference in differential cross sections for electron scattering between any two nuclear levels with incident longitudinally polarized right- and left-handed electrons is derived. This difference must involve the parity-violating weak interaction at least linearly and can be used to study weak neutral currents as pointed out by Feinberg. A V — A structure for the weak neutral currents is assumed with a semi-leptonic current-current interaction, and the electromagnetic interaction is treated in the one-photon-exchange approximation. The result is expressed in terms of the same set of reduced matrix elements of the multipoles of the nuclear currents which govern all electromagnetic and weak transitions between these levels. A previously developed unified analysis of semi-leptonic weak and electromagnetic interactions in nuclei which determines one-body transition densities, including their spin and spatial dependences, through electron scattering provides nuclear transitions to serve as known analyzers in testing the structure of this part of the weak interaction. Examples are given using Weinberg's model of the weak neutral currents. Feinberg's result for elastic scattering from spin-0 nuclei is rederived and two new examples using previously determined one-body densities are discussed : the 1⁺0 → 0⁺1 (3.56 MeV) transition in ⁶Li and the 0⁺0 → 1⁺ 1(15.1 MeV) transition in ¹²C.     

Weak neutral-current effects in electron-scattering coincidence experiments

Using a recently developed helicity analysis of electron-scattering coincidence experiments, we derive general expressions for the asymmetry in the coincidence cross section with polarized incident electrons. The asymmetry cross section is expressed in terms of the helicity components of the electromagnetic and weak neutral currents in the center-of-momentum frame. The asymmetry arises from an interference between the electromagnetic and weak neutral currents and from parity admixtures in the nuclear wave functions. In the limit of heavy, static nuclei, connection can be made to the usual multipole matrix elements of the electromagnetic and weak interactions. Some simple examples are discussed for the case where the reaction proceeds through a single intermediate resonance.     

Fullerenes as polyradicals

We present the investigation of the electronic structure of X₆₀ molecules (X=C, Si), containing 60 odd electrons with spin-dependent interaction between them. Conditions for the electrons to be excluded from the covalent pairing are discussed. A computational spin-polarized quantum-chemical scheme is suggested to evaluate four parameters—energy of radicalization, exchange integral, atom spin density, and squared spin— to characterize the effect quantitatively. A polyradical character of the species, weak for C₆₀ and strong for Si₆₀, is established.     

Mixing of neutral atoms and lepton number oscillations

We discuss oscillations of two neutral atoms which proceed with the violation of lepton number. One of the neutral atoms is stable, the other one represents a quasistationary state subjected to electromagnetic deexcitation. The system of neutral atoms exhibits oscillations similar to those of the system of neutral kaons and neutron-antineutron oscillations in the nuclear medium. The underlying mechanism is a transition of two protons and two bound electrons to two neutrons p + p + e _b ⁻ + e _b ⁻ ↔ n + n. A signature of the oscillations might be an electromagnetic deexcitation of the involved unstable nucleus and atomic shell with the electron holes. A resonant enhancement of the neutrinoless double electron capture takes place when the atomic masses tend to be degenerate. Qualitative estimates show that in searches for lepton number violation oscillations of atoms might be a possible alternative to the conventional mechanism of the neutrinoless double β decay process with emission of two electrons. The article is published in the original.     

Novel time-reversal tests in low-energy neutron propagation

Interesting time-reversal tests are possible for low-energy neutrons propagating in polarized materials. We present a class of tests, involving comparison of spin states, which avoid the difficulty of rotations induced by fields in the material. Such transmission experiments would permit the use of sensitive neutron-spin-measuring techniques and thus refined searches for T-violation in nuclear interactions.     

Parity nonconservation in deuteron photoreactions

We calculate the asymmetries in parity-nonconserving deuteron photodisintegration due to circularly polarized photons $ \vec \gamma d \to np $ \vec \gamma d \to np with the photon laboratory energy ranging from the threshold up to 10MeV and the radiative capture of thermal polarized neutrons by protons $ \vec np \to \gamma d $ \vec np \to \gamma d . We use the leading-order electromagnetic Hamiltonian neglecting the smaller nuclear exchange currents. Comparative calculations are done by using the Reid93 and Argonne v₁₈ potentials for the strong interaction and the DDH and FCDH “best” values for the weak couplings in a weak one-meson exchange potential. A weak NΔ transition potential is used to incorporate also the Δ(1232) -isobar excitation in the coupled-channels formalism.     

Neutronization and Protonization of Nuclei: Two Possible Ways of the Evolution of Astrophysical Objects and the Laboratory Electron-Nucleus Collapse

We consider the peculiarities of the fundamental nuclear transformations running both in the shell of a heavy star compressed by the strong gravitational field and during the laboratory electron-nucleus collapse where the compression occurs at the expense of the electron-nucleus interaction in a volume occupied by a degenerate electron gas, define their analogs, and analyze the differences. It is shown that the account of relativistic and nonlinear corrections to the Coulomb electron-nucleus interaction gives the possibility to realize two alternative ways for the evolution of the star matter which depend on both the rate of compression upon the gravitational collapse and the initial isotope composition of a star on the stage preceding the collapse. Upon the relatively slow compression of a heavy star in the process of gravitational collapse after the attainment of the threshold electron density, there occur the stage-by-stage neutronization of nuclei and the formation of a neutron star with a great concentration of neutrons and a low concentration of protons and electrons. This process is characterized by the presence of a bounded interval of the density of a relativistic degenerate gas of electrons (“the neutronization corridor”), in the scope of which the neutronization runs with a decrease in the Fermi energy and the release of energy in the form of fast neutrinos. At a higher electron density, the process of protonization becomes energy-gained. In this case, an increase in both the charge of nuclei and the concentration of degenerate electrons causes the continuous increase in the binding energy of electrons and nuclei which turns out to be more significant than the increase in the Fermi energy of electrons. The transition of nuclei through “the neutronization corridor” into “the protonization zone”, which ranges up to the nuclear density of a substance, is possible only in the case of a very fast compression of a heavy star. Such a process leads to the possibility of the formation of proton stars with a very small residual concentration of neutrons and a great (nuclear) concentration of protons and electrons. It is shown that analogous effects can be realized during the laboratory electron-nucleus collapse. Due to a microscopic size of the collapse zone, a great velocity of its formation, and a relatively low rate of neutronization, the passage of the electron-nucleus substance through “the neutronization corridor” weakly affects its state. In this case, the main mechanism of transformations is the process of protonization with a simultaneous increase in the concentration of degenerate electrons.     

Determination of Atomic Masses and Nuclear Binding Energies via Neutron Induced Reactions

Information on atomic masses and nuclear binding energies can be extracted from (n,p) and (n, α) reactions with thermal and resonance neutrons. This is illustrated by means of several selected examples. This revised version was published online in July 2006 with corrections to the Cover Date.     

Neutron- and muon-induced background in underground physics experiments

Background induced by neutrons in deep underground laboratories is a critical issue for all experiments looking for rare events, such as dark matter interactions or neutrinoless ββ decay. Neutrons can be produced either by natural radioactivity, via spontaneous fission or (α, n) reactions, or by interactions initiated by high-energy cosmic rays. In all underground experiments, Monte Carlo simulations of neutron background play a crucial role for the evaluation of the total background rate and for the optimization of rejection strategies. The Monte Carlo methods that are commonly employed to evaluate neutron-induced background and to optimize the experimental setup, are reviewed and discussed. Focus is given to the issue of reliability of Monte Carlo background estimates. We dedicate this work to the memory of our friend and colleague Nicola Ferrari, who prematurely passed away in July 2006.     

Inelastic final-state interactions in B → VV →π K processes

We study the final-state interactions in B →π K decays through B → VV →π K processes where the inelastic rescattering occurs via single pion exchange. The next-to-leading order low-energy effective Hamiltonian and Bauer-Stech-Wirbel (BSW) model are used to evaluate the weak transition matrix elements and final-state interactions. We found that the final-state interaction effects in B →ρ K^*→π K processes are significant. The Fleischer-Mannel relation for the Cabibbo-Kobayashi-Maskawa (CKM) angle γ can be significantly modified. Received: 13 August 1998