Deuterium Capture Research Articles

The peculiarities of implanted deuterium capture in Kh16N15M3T1 austenitic steel with different structure

The results of studying of implanted hydrogen (deuterium) capture in austenitic steel Kh16N15M3T1 are reported. The peculiarities and possibilities of using the nuclear reactions method for measuring deuterium capture are discussed. The traps of implanted atoms and their capture by the elements of steel structure under radiation damage are considered. It is shown that the segregation intensity depends on the initial structure of the samples. A method is proposed for separating the contribution from different types of traps - structure elements - to implanted deuterium capture in irradiated volume. The mechanism of formation and evolution of radiation-induced segregation is discussed.

Deuterium accumulation in tungsten under low-energy high-flux plasma exposure

The accumulation of deuterium implanted in tungsten is simulated within the framework of kinetic diffusion theory. The influence of the tungsten microstructure (dislocation density and impurity concentration) on the process of deuterium capture and accumulation is considered. It is established that, under the chosen irradiation conditions, deuterium accumulation in the near-surface region is determined by capture at defects formed during implantation. The deuterium concentration gradient, together with the material microstructure, determines its accumulation in tungsten. Variation in the dislocation density and impurity concentration does not affect the simulation results, which is, first, related to the fact that the model used does not contain alternative mechanisms for the formation and growth of vacancy clusters under the subthreshold irradiation mode. The simulation results are compared with experimental data, and ways of improving the model are discussed in order to explain the deuterium-saturation effect for high fluences (more than 1023 m−2).

Calculation of doublet capture rate for muon capture in deuterium within chiral effective field theory

The doublet capture rate Λ1/2 of the negative muon capture in deuterium is calculated employing the nuclear wave functions generated from accurate nucleon–nucleon (NN) potentials constructed at next-to-next-to-next-to-leading order of heavy-baryon chiral perturbation theory and the weak meson exchange current operator derived within the same formalism. All but one of the low-energy constants that enter the calculation were fixed from pion–nucleon and nucleon–nucleon scattering data. The low-energy constant dˆR (cD), which cannot be determined from the purely two-nucleon data, was extracted recently from the triton β-decay and the binding energies of the three-nucleon systems. The calculated values of Λ1/2 show a rather large spread for the used values of the dˆR. Precise measurement of Λ1/2 in the future will not only help to constrain the value of dˆR, but also provide a highly nontrivial test of the nuclear chiral EFT framework. Besides, the precise knowledge of the constant dˆR will allow for consistent calculations of other two-nucleon weak processes, such as proton–proton fusion and solar neutrino scattering on deuterons, which are important for astrophysics.

Muon capture in deuterium

Model dependence of the capture rates of the negative muon capture in deuterium is studied starting from potential models and the weak two-body meson exchange currents constructed in the tree approximation and also from an effective field theory. The tree one-boson exchange currents are derived from the hard pion chiral Lagrangians of the N Δ π ρ ω a 1 system. If constructed in conjunction with the one-boson exchange potentials, the capture rates can be calculated consistently. On the other hand, the effective field theory currents, constructed within the heavy baryon chiral perturbation theory, contain a low energy constant d ˆ R that cannot be extracted from data at the one-particle level nor determined from the first principles. Comparative analysis of the results for the doublet transition rate allows us to extract the constant d ˆ R .

Polarized proton pionic capture in deuterium as a probe of3Ndynamics

The proton analyzing power Ay in pion production reaction pd --> pi0 3He has been calculated including one- and two-body meson production mechanisms with a proper treatment of the three-nucleon dynamics and an accurate solution of the 3N bound-state problem for phenomenological two-nucleon potentials. In the region around the Delta resonance, the structure of the analyzing power can be understood once interference effects among amplitudes describing intermediate Delta N formation in different orbital states are considered along with the additional interference with the S-wave pion production amplitudes. Then, the inclusion of three-nucleon dynamics in the initial state produces the structure of the analyzing power that has been observed experimentally.

MUON CAPTURE IN DEUTERIUM

Muon capture in deuterium, μ-+ D →νμ+n+n, is a weak process of fundamental importance. The capture rate depends critically on the spin configuration of the initial (μ D ) state, which is in turn related closely to the availability of having two nearby deuteron nuclei. In this paper, we calculate the capture rates from the doublet [Formula: see text] and quartet [Formula: see text] hyperfine states. In addition to using the gaseous or liquid deuterium target, we wish also to propose to employ the deuterated target such as PdD or TiD to carry out the muon capture measurement, since it is known that the transition metals such as palladium (Pd) or titanium (Ti) has unusually high deuteron (hydrogen) absorption properties.

Bulk retention of deuterium in graphites exposed to deuterium plasma at high temperature

A highly ionized deuterium plasma with a low residual gas pressure and a high intensity D 2 +-ion beam were used for the study of deuterium retention in RG-Ti-91 and POCO AXF-5Q graphites. Deuterium retention in the samples was estimated by TDS during heating to 2000 K. Mechanical removal of a surface layer 100 μm thick was used to distinguish bulk and surface fractions of retained deuterium. The samples of RG-Ti and POCO graphites were exposed to a plasma with an ion flux of 3 × 10 17 D/cm 2 · s in the ‘Lenta’ plasma device for 10 to 10 4 s at residual deuterium pressure of 0.04 Pa at 1400 K. Under plasma exposure deuterium capture in RG-Ti graphite reached the saturation level at a fluence of 4 × 10 20 D/cm 2 while the bulk inventory was negligible. As for POCO graphite, deuterium retention increased with fluence and was equal to 18 appm in the bulk for a fluence of 7 × 10 21 D/cm 2. The same amount of deuterium in the bulk was obtained after gas exposure of POCO at an effective pressure of 0.8 Pa (1400 K, 6 h). With this result, the tritium concentration in the plasma-facing graphite materials can reach 1500 appm or 380 grams of tritium per ton of graphite. To understand the role of ion flux in generation of effective pressure, POCO was irradiated with 16 keV D 2 +-ions at 1400 K for 4 h to 8 × 10 20 D/cm 2 (ion flux was 6 × 10 16 D/cm 2 · s, residual deuterium pressure was 0.004 Pa). The results are discussed on the basis of structural differences for POCO and RG-Ti graphites.

Effect of carbon on the structure and deuterium capture and liberation from Fe-C alloys

Effect of carbon on the structure and deuterium capture and liberation from Fe-C alloys

Muon capture in deuterium and the meson exchange current effect

One-meson exchange current effect in reaction μ − + d → 2 n + v μ is calculated by using the weak axial current operator which satisfies the nuclear continuity equation up to the order 1 M 2 ( M is the nucleon mass). In the vector part of the weak nuclear interaction the vector-isovector pion exchange currents are also included. Their contribution is found to be non-negligible. The nuclear wave functions are generated from the Paris, Reid soft-core and Bonn potential models. Our result is compatible with the previous one, obtained with only the static axial exchange currents included.

Energetic neutron emission from μ −-capture in deuterium

The neutron spectrum from 25 to 52 MeV resulting from μ −-capture in liquid deuterium was measured by a time-of-flight technique. The spectrum near the end point exhibited an enhancement consistent with the meson-exchange-current calculations.

Exchange currents and extraction of ann and gP from negative MUON capture in deuterium

It is shown that the value of the neutron-neutron scattering length a nn extracted from the normalized differential neutron spectra measured in the reaction μ − + d → 2n + ν μ can be changed by up to ≈ −0.07 fm by the axial meson exchange current (MEC) effects, this being comparable in magnitude to the error in a nn due to the uncertainty of 0.2 fm in r nn. The kinematical region is found where the influence of these effects on the extraction of a nn is minimal. Due to the MEC effects, the value of g P obtained from the ratio of the quadruplet Γ q to the doublet Γ d transition rate is changed by ≈0.5 g A. We also confirm that the normalized neutron spectra are sensitive to a reasonably small variation of a nn.

Hard pions and axial meson exchange current effects in negative muon capture in deuterium

The contribution of the axial meson exchange current effects to the doublet transition rate in the reaction μ − + d → 2 n+ ν μ is calculated by using the minimal, chiral and approximately gauge invariant Lagrangian model for the A 1ρπ system. The contribution from the ρ-π weak decay process current usually considered is found to be nearly cancelled by that from the A 1 pole graph which is prescribed by the underlying invariance principles. Correct treatment of the N ∗ propagator in the N ∗ excitation current of the pion range leads to ≈ 30 % suppression of the N ∗ effect.

Muon capture in deuterium with realistic potentials

Abstract The transition rates for muon capture in deuterium are calculated using the Reid soft-core deuteron, and 1 S 0 and 3 P J (J = 0, 1, 2) neutron-neutron wave functions. The validity of the closure approximation and of the Omnes-Muskhelishvili method is studied. The off-shell effects admissible in a class of phase-shift-equivalent potentials by present experimental data are evaluated.

Muon-Capture Rates in Deuterium and the Weak Form Factors in the Timelike Region

The rates for muon capture in deuterium from the doublet and quartet states are calculated by the use of the elementary-particle treatment. The matrix elements of the vector and axial-vector currents are each constructed in terms of two independent form factors. The form factors describing the matrix element of the vector current are obtainesd in the spacelike region from electrodisintegration and photodisintegnation data by the use of the conserved- vector-current hypothesis. The form factors describing the matrix element of the axial-vector current are obtained in the spacelike region by the use of the hypothesis, of partial conversation of axial-vector current and arguments based on the impulse approximation. The capture rates are found to be sensitive to the behavior of the form factors near q/sup 2/ = m/sub mu //sup 2/. The capture rates from the doublet and quartet states are fou nd t, be GAMMA /sub d/ = 374 plus or minus 18 sec/sup -1/ and GAMMA /sub q/ = 6.07 plus or minus 0.04 sec/ sup muons plus :q1; muons minus :q1; gev range 10-100; It is shown that 25.6% of the contribution to GAMMA /sub d/ comes from the timelike region and that an analytic continuation of themore » dipole fit for the form factors to the timelike region from the spacelike region is consistent with experimental data. (auth)« less

Muon capture in deuterium

The muon capture in deuterium is studied by means of the impulse approximation with relativistic corrections. The deuteron is described by means of theS- andD-wave.

Relativistic treatment of muon capture in deuterium: Application to the determination of neutron-neutron scattering length and effective range

This paper is devoted to a relativistic calculation of muon capture in deuterium. The important effect of hyperfine structure is treated relativistically. The aim of this work is a determination of neutron-neutron scattering length and effective range. We use vertex functions to describe the proton-neutron-deuteron vertex and the Omnès method to compute the final-state interaction. It is shown that an accuracy of 2.5% in spectrum and capture rate must allow a determination of r os and a s with an accuracy of, respectively, ±0.2 fm and ±0.7 fm.

The influence of the neutron-neutron final-state interaction on the capture of muons by deuterons

The influence of the neutron-neutron final-state interaction on the μ capture in deuterium is calculated. It is shown that this process allows from the theoretical point of view a determination of the neutron-neutron scattering length with an accuracy of about 5%.

The non-mesic interactions of K − mesons in helium

The non-mesic capture processes of K − mesons in helium have been investigated using a model first developed in a previous work 1) for understanding the corresponding captures in deuterium. It is found that the calculated branching ratio for K − non-mesic transitions in helium is of the observed order of magnitude as was found to be the case for capture in deuterium. With this model it is shown that the close nuclear correlations in the helium nucleus are better represented by an Irving wave function than by a Gaussian wave function.

Erratum to: Λ-Nucleon scattering in K--deuterium capture reactions at rest

Erratum to: Λ-Nucleon scattering in K--deuterium capture reactions at rest

Gamma Rays from Neutron Capture in Helium-3 and Deuteron Capture in Deuterium

The gamma rays from the ${\mathrm{He}}^{3}(n, \ensuremath{\gamma}){\mathrm{He}}^{4}$ and the $\mathrm{D}(d, \ensuremath{\gamma}){\mathrm{He}}^{4}$ reaction have been observed. The gamma detector, a 3-in.\ifmmode\times\else\texttimes\fi{}4-in. NaI crystal, was surrounded by a plastic scintillator to eliminate the cosmic-ray background. A pileup rejection circuit was used to reduce the background from neutron induced reactions in the NaI. The cross section of the ${\mathrm{He}}^{3}(n, \ensuremath{\gamma}){\mathrm{He}}^{4}$ reaction at 4 MeV is $\ensuremath{\sigma}=5$ \ensuremath{\mu}b/sr at 90\ifmmode^\circ\else\textdegree\fi{}. The intensity ratio, $\frac{I(90\ifmmode^\circ\else\textdegree\fi{}}{I(45\ifmmode^\circ\else\textdegree\fi{})}\ensuremath{\approx}2$, agrees with that expected for electric dipole radiation ($\ensuremath{\Delta}M=0$). The $\mathrm{D}(d, \ensuremath{\gamma}){\mathrm{He}}^{4}$ reaction at 1.35 MeV has a cross section $\ensuremath{\sigma}=2\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}33}$ ${\mathrm{cm}}^{2}$/sr at 45\ifmmode^\circ\else\textdegree\fi{}.