Deuteron Pair Research Articles

A study of the effects of the cathode configuration on the plasma kinetics and neutron emission of plasma-focus discharges in deuterium

The differences in performance of a 1.9 kJ plasma-focus device PACO assembled with three different cathode configurations are experimentally qualified. In particular, the current sheath kinetics and the neutron yield operating with deuterium gas are systematically studied for the whole range of neutron-producing pressures, and the measurements are analyzed searching for relations between relevant physical magnitudes. The pinching time was found correlated with the dimensionless driver parameter, and this feature was found statistically independent of the cathode. The variation of the inductance jump associated with the radial collapse stage is used to estimate the effective pinch length, mm, and radius, mm. The maximum production in a single shot was registered for the smallest cathode radius, 41 mm, whereas the intermediate cathode radius, 45 mm, scored better in average. In all configurations, the neutrons per deuteron pair correlates fairly well with an estimation of the effective equilibrium temperature of the pinch, which suggests a prevalence of thermonuclear neutrons measured perpendicularly to the focus axis.

The hydrogen anomaly problem in neutron Compton scattering

Neutron Compton scattering (also called ‘deep inelastic scattering of neutrons’, DINS) is a method used to study momentum distributions of light atoms in solids and liquids. It has been employed extensively since the start-up of intense pulsed neutron sources about 25 years ago. The information lies primarily in the width and shape of the Compton profile and not in the absolute intensity of the Compton peaks. It was therefore not immediately recognized that the relative intensities of Compton peaks arising from scattering on different isotopes did not always agree with values expected from standard neutron cross-section tables. The discrepancies were particularly large for scattering on protons, a phenomenon that became known as ‘the hydrogen anomaly problem’. The present paper is a review of the discovery, experimental tests to prove or disprove the existence of the hydrogen anomaly and discussions concerning its origin. It covers a twenty-year-long history of experimentation, theoretical treatments and discussions. The problem is of fundamental interest, since it involves quantum phenomena on the subfemtosecond time scale, which are not visible in conventional thermal neutron scattering but are important in Compton scattering where neutrons have two orders of magnitude times higher energy. Different H-containing systems show different cross-section deficiencies and when the scattering processes are followed on the femtosecond time scale the cross-section losses disappear on different characteristic time scales for each H-environment. The last section of this review reproduces results from published papers based on quantum interference in scattering on identical particles (proton or deuteron pairs or clusters), which have given a quantitative theoretical explanation both regarding the H-cross-section reduction and its time dependence. Some new explanations are added and the concluding chapter summarizes the conditions for observing the specific quantum phenomena observed in neutron Compton scattering on protons and deuterons in condensed systems.

Fast atoms and negative chain-cluster fragments from laser-induced Coulomb explosions in a super-fluid film of ultra-dense deuterium D(−1)

Fragments from laser-induced Coulomb explosions (CE) in a thin super-fluid film of ultra-dense deuterium D(−1) on a vertical surface are now observed by both negative and positive time-of-flight mass spectrometry. The so-called normal phase of the super-fluid is probably associated with D4 clusters and gives only neutral atomic fragments with a kinetic energy from the CE of 945 eV. The super-fluid phase is associated with long chain clusters D2N with N deuteron pairs and gives cluster fragments by CE mainly with a kinetic energy of 315 eV from the central cleavage in a neutral, positive or negative form. This indicates that the chain clusters are standing perpendicularly to the surface. The fragment charge state is influenced by the external field, which indicates efficient charge transfer processes.

Effects of Entanglement on the Scattering Intensity of Neutron Compton Scattering by a Proton Pair in Solids

We calculate scattering functions S(q-->,omega) of neutron Compton scattering (NCS) for a proton (deuteron) pair in the entangled state caused by the indistinguishability of particles. From the calculation, it is concluded that the effect of entanglement on the scattering intensity is undetectable in NCS experiments because of their high energy transfer and broad energy resolution.

QUANTUM COHERENCE IN NEUTRON SCATTERING ON PROTONS

Several recent observations of closely spaced hydrogen nuclei in condensed matter systems — water, polymers and metal hydrides — indicate that they cannot be considered as independent quantum objects when observed over very short time intervals. According to these measurements, pairs (or possibly small clusters) of protons or deuterons seem to be quantum correlated, and are able to preserve their mutual quantum phase relations over times of the order of femtoseconds even in strongly perturbing liquid or solid environments. These new experimental results are mainly based on scattering of neutrons with time windows in the atto- and femtosecond range, but there also exists corroborating evidence from other spectroscopies. When the width of the observational time window is increased above a characteristic value, the quantum coherence effects are seen to disappear. This time limit marks the onset of decoherence as the mutual phase relations between the particles are gradually lost. Possible reasons for short-time entanglement of nuclei in condensed matter systems, as well as mechanisms for its decoherence will be discussed.

Observation of a nearly isotropic, high-energy Coulomb explosion group in the fragmentation ofD2by short laser pulses

We have used momentum spectroscopy to examine the production of deuteron pairs in the double ionization of ${\mathrm{D}}_{2}$ molecules by a fast $(<200 \mathrm{fs}),$ moderately intense $[(0.65--8.0)\ifmmode\times\else\texttimes\fi{}{10}^{14} \mathrm{W}/{\mathrm{cm}}^{2}]$ laser pulse. By measuring in coincidence the momentum vectors of both deuterons, we have isolated, at the lowest laser power density, a weak ionization channel characterized by Coulomb-explosion deuterons with a sum energy near 10 eV. This is much higher than has been seen in previous studies. The angular distribution of these deuterons is nearly isotropic, in contrast to previous observations that the deuterons are strongly peaked along the laser polarization. These new observations suggest a previously unobserved ionization mechanism.

An indication of slowing down of hydrogen atom transfer in isotopically mixed hydrogen bonds of benzoic acid crystals

Benzoic acid molecules form a dimeric unit of carboxyl groups in the crystalline phase and two acid protons form a pair. In the case of a proton/deuteron mixed hydrogen-bond system, proton–deuteron pairs (HD pairs) as dimers may exist in a stochastic distribution probability depending on the mole fraction of deuteron. Transfer rates of proton and deuteron in the HD pairs were investigated by spin–lattice relaxation rate T1−1 of proton and deuteron NMR, respectively, for a series of different mole fractions of deuteron in the hydrogen bonds. For the measurement of the spin–lattice relaxation rate of the proton, 17O was enriched to provide an additional relaxation pathway and enhance the signature of the HD pairs in the spin–lattice relaxation. The rates of proton and deuteron transfer in the HD pairs were in between those of the proton transfer in fully protonated specimen (HH pairs) and the deuteron transfer in fully deuterated specimen (DD pairs). This result indicates that H and D in the HD pairs transfer in a concerted manner within the time-scale of NMR (10−6–10−10 s). Here we found an interesting result that the transfer rate of the HD pairs in the high-temperature region decreased as the mole fraction of deuteron of hydrogen bonds in the crystal was increased from 0.13 to 0.96. This result is semiquantitative at present and the precise value of the transfer rate may depend on the method of analysis. However, an estimation of the decrease is almost one order of magnitude at 200 K. Although this effect should be strictly confirmed by other experiments, an indirect geometrical isotope effect for the hydrogen bond length and/or some dynamic correlation among dimers may be responsible for this phenomenon. Copyright © 2001 John Wiley & Sons, Ltd.

Observation ofd-dFusion Neutrons during Degassing of Deuterium-Loaded Palladium

Experiments with two massive deuterium-loaded palladium samples designed to search for deuteron-deuteron (d-d) fusion during thermal degassing are described. In the heavier of the two samples, which has a total mass of [approximately] 0.5 kg, during deuterium expulsion from the metal, a significant neutron excess count rate was detected by two independent NE-213 scintillation neutron detectors. The maximum time-dependent excess count rate corresponds to a d-d reaction rate of (3 [+-] 1) [times] 10[sup [minus]25] per deuteron pair per second. From detector pulse height spectra, the energy of the neutrons is determined to be [approximately] 2.5 MeV, as expected for d-d fusion neutrons. 10 refs., 10 figs., 2 tabs.

Cluster-impact fusion: Yields from binary-collision sequences

Abstract Theory is developed for dd fusion resulting from the impact of accelerated clusters of D2O on deuterated solid targets. Sequences of collisions between D atoms and heavy atoms of the beam and target are studied as a mechanism for quickly increasing the relative velocities of pairs of deuterons. Fusion yields are calculated as a sum over 10 such sequences. Calculated yields are many orders of magnitude smaller than the results reported by Beuhler, Friedlander, and Friedman. Implications of these differences are discussed.

Search for the cold fusion d(d, 4He) in electrolysis of D 2O

A search for high-energy α-particlesfrom the reaction d+d+Pd|Ti| → 4He+Pd′|Ti′| has been carried out using track detectors CR-39 and silicon surface barrier detectors. The upper limit of the investigated partial reaction rate has been estimated per deuteron pair: λ(d+d+Pd|Ti| → 4He+Pd′|Ti′|vb) ⩽ 8 × 10 −27 s −1 .

Cold fusion in palladium: a more realistic calculation.

The Thomas-Fermi-Mott equation is modified to take account of the fact that conduction electrons in a metal may be considered to have an effective mass at wave-numbers comparable with or less than the inverse Debye screening length, but they should be considered to have the free-electron mass at much larger wavenumbers. This modification allows for a more realistic calculation of the fusion rate of deuteron pairs in palladium, this rate being 10(-23) sec-1, comparable with some experimental results. The Oppenheimer-Phillips process enhances the rate by a factor of 2.262.

Further Measurements on Electrolytic Cold Fusion with D2O and Palladium at Gran Sasso Laboratory

This paper reports on several experiments performed at the Gran Sasso Laboratory on an 0.8-cm-diam {times} 5-cm-long, hyperpure, high-temperature vacuum-annealed palladium rod used as a cathode for electrolytic infusion of D{sub 2}O and 0.1 M LiOH with regular additions of gaseous CO{sub 2} at a current density of 60 mA/cm{sup 2}. In the very low background radiation environment, several gamma bursts lasting up to 15 min were detected whose intensity, in terms of cold fusion, was {gt}10{sup {minus} 20} fusion/(deuteron pair {center dot} s). Under normal background conditions, none of these burst signals would have been detected with statistical significance. The shape and intensity of these signals are quite similar to those detected previously.

Once more about cold nuclear fusion

Results of the experiments on the search for cold nuclear d-d fusion in chemically pure titanium are given both for electrolysis of heavy water D 2O and for titanium saturation with deuterium gas. The saturation took place at a temperature of 77 K and pressures of 50 and 150 atm. A series of experiments with temperature varying from 1 to 600 atm was carried out. The limiting values of the partial rate of the nuclear reaction of d-d fusion with neutron production were obtained per deuteron pair (at 95% confidence level): λ f ⩽8×10 -27 s -1 (experiment with deuterium gas).

More cold fusion in metals: corrected calculations and other considerations.

A simple model of a metal containing deuterons is considered. The example of palladium is treated in detail. In contrast to a previous calculation, it is shown that the effect of screening of Coulomb fields by conduction electrons is sufficient to allow a deuteron pair to fuse at a rate of 10(-18) sec-1, five powers of 10 larger than some experimental results. It is shown that the Oppenheimer-Phillips process enhances the rate by a factor of 1.77. Difficulties with applying the model to titanium are discussed.

Cold fusion in metals

A simple model of a metal containing deuterons is considered. The example of palladium is treated in detail. It is shown that the effect of screening of Coulomb fields by conduction electrons is sufficient to allow deuteron pairs to fuse at rates of 10(-30) sec(-1), seven orders of magnitude smaller than those reported by Jones et al. [Jones, S. E., Palmer, E. P., Czirr, J. B., Decker, D. L., Jensen, G. L., Thorne, J. M., Taylor, S. F. & Rafelski, J. (1989) Nature (London) 388, 737-740].

Virtual-State Internal Nuclear Fusion in Metal Lattices

A model of deuterium-deuterium (D-D) fusion in metal lattices is presented based on two phenomena: (a) reactions between virtual-state pairs of deuterons “bound” by electrons of high effective mass m* and (b) deuterium energy upscattering by fast ions from fusion or tritium reactions with virtual-state nuclear structure groups in palladium nuclei. Since m* is a decreasing function of deuterium ion bulk density n0, the exponential barrier tunneling factor decreases rapidly with m*. As a result, the fusion rate reaches a maximum at a loading density above zero but less than saturation. This can explain observations of transient neutron output from the (3He,n) branch of D-D fusion. At low energy, D-D reactions favor the (T,p) branch. Fast product tritium may be captured by palladium isotopes to form excited-state Ag*, removing tritium from the system and preventing deuterium-tritium fusion. This may decay by alpha or proton emission, yielding fast ions and excited state Rh* or Pd*. Fast ion collisional “trapping” may occur at Fermi electron speeds, enhancing in situ upscattering and yielding increased D-D reaction rates. Analysis of the dynamics of these processes suggests conditions for exponential growth.

Can solid-state effects enhance the cold-fusion rate?

RECENTLY two groups1,2 have reported finding experimental evidence for an unexpectedly high rate of nuclear fusion at room temperature during the process of electrolytic deposition of deuterium on palladium1,2 and titanium2. To achieve the rate of neutron production (∼10−23s−1 per deuteron pair) cited in ref. 2 (and a fortiori, that inferred in ref. 1) requires the solid-state environment to produce either an unusual enhancement of the fusion reaction rate or a large suppression of the Coulomb barrier between deuterons. The latter would presumably arise from some kind of sophisticated many-body screening effect in Pd or Ti, perhaps associated with quasiparticles of large effective mass2. Here we point out that within the framework of the lowest-order Born-Oppenheimer approximation, a very severe constraint is imposed on all such screening mechanisms in solids in equilibrium by the observable binding affinity of 4He atoms for the metal in question. Unless the latter is quite anomalous, the Coulomb barrier penetration in a solid in equilibrium cannot be enhanced anywhere near the magnitude required to explain the fusion rates inferred from the experiments.

The effect of cholesterol on lipid dynamics and packing in diether phosphatidylcholine bilayers. X-ray diffraction and 2H-NMR study

In order to compare the lipid packing, conformation and dynamics of ether- and ester-linked phosphatidylcholines in the presence of equimolar concentrations of cholesterol, multilamellar dispersions of these lipid-sterol mixtures were investigated by X-ray diffraction and 2H-NMR. A comparison of the X-ray diffraction patterns at 22° C of 1,2- di-O- hexadecyl-sn- glycero-3- phosphocholine (DHPC) and 1,2- dipalmitoyl-sn- glycero-3- phosphocholine (DPPC) dispersions, each containing 50 mol% cholesterol, demonstrate that the structural characteristics of DHPC and DPPC bilayers in the presence of cholesterol are essentially indistinguishable by X-ray diffraction. In contradistinction to the similar structural characteristics of DHPC and DPPC in the presence of cholesterol, the low-angle lamellar reflections of DHPC at 22° C in the absence of cholesterol are indicative of an interdigitated phase, demonstrating that cholesterol facilitates the conversion from an interdigitated to a non-interdigitated phase. Above T c in each lipid-sterol mixture, the quadrupolar splittings from the α-methylene segments of 1,2[1′,1′- 2H 2]DHPC and 1,2[2′,2′- 2H 2]DPPC indicate that both chain inequivalence and magnetic inequivalence of any particular α-C 2H 2 deuteron pair are preserved and actually enhanced in the presence of cholesterol. Lowering of the temperature below T c in 1,2[2′,2′- 2H 2]DPPC/cholesterol dispersions leads to a progressive intensity loss of the sn-2 chain components, a thermotropic effect which is not observed in the corresponding components of the 1,2[1′,1′- 2H 2]DHPC/cholesterol spectra.

One-dimensional ordering of deuterium in solution in yttrium

Diffuse neutron scattering measurements on a single crystal of alpha -YD0.17 indicate an order-disorder transition between 170 K and 280 K. Above 280 K, a broad ridge of scattering intensity in a plane normal to the (00l) direction at l approximately 4/3 indicates that the deuterons have formed pairs on next-nearest tetrahedral sites along the c direction of the yttrium host lattice. As the temperature is lowered through the transition region, the feature becomes narrower and more intense and shifts somewhat closer to the l=4/3 position. This behaviour can be largely explained by a simple model that assumes a repulsive hard-core plus long-range attractive potential between deuteron pairs along lines in the c direction. As the temperature is reduced these interactions cause the deuterons to arrange themselves in lines along this direction, each line being uncorrelated with all other such lines. The origin of the interaction is presumably electronic and may lie in the nature of the Fermi surface of yttrium.

Signs of deuteron quadrupole coupling constants from COSY-2D spectra of solids

It is shown how the signs of the quadrupole coupling constants (QCCs) of deuterons can be determined from the multiplet structures of the cross peaks in COSY-2D spectra of deuterons in molecular crystals or any other ordered sample. Multiplets arise as a result of dipolar couplings between pairs of deuterons. The 21) multiplet of a cross peak of a dipolar-coupled pair of deuterons consists of a 3 × 3 array of component lines. If the mixing pulse of the COSY sequence is a 90° pulse the multiplet is insensitive to the signs of the deuteron QCCs. If, however, the mixing pulse is a 54°44′ pulse only four of the nine components are strong. These are located in one of the four corners of the 3 × 3 array. In which comer of the 3 × 3 array the four strong peaks appear depends on the relative signs of the dipolar and quadrupolar splittings D, Δω Q1 and Δω Q2. This can be used as a fingerprint for the relative signs of D, D, Δω Q1 and Δω Q2. The experimental conditions of the procedure are explored in an experiment on a single crystal of fully deuterated potassium oxalate monohydrate.