Deuterium Target Research Articles

Potential for suprathermal chain reactions in degenerate deuterium plasmas at high densities

Abstract It is argued that fusion chain reactions in the D-D system are feasible with
supra-thermal deuterons in the MeV regime, with new generations of deuterons being
generated either via neutron-deuteron and proton-deuteron collisions, provided that fuel
densities in excess of 1000 gcm −3 are reached. The propagation of supra-thermal deuterons
in an infinite, dense deuterium target was studied using a Monte Carlo method that includes
multiple nuclear reactions, electron and ion stopping, along with neutron and proton
knock-ons. Prior studies into this system are extended and it is shown that : (a)dense
pure deuterium may be more supportive of chain reactions via refinements to the ion-ion
stopping number, (b) such chain reactions can be supported even when the target is electron
degenerate, and (c) the D-T reaction plays a critical role in sustaining these chain reactions.

Suprathermal-ion-driven fusion chain reactions in the pure deuterium system

It is argued that fusion chain reactions in the D-D system is feasible with supra-thermal deuterons in the MeV regime, with new generations of deuterons being generated either via neutron–deuteron or proton–deuteron collisions. The propagation of supra-thermal deuterons in an infinite, hot, dense deuterium target was studied using a Monte Carlo method that includes multiple nuclear reactions, electron and ion stopping, along with neutron and proton knock-ons. Over a wide range of densities we observed significant, albeit sub-critical chain reactions in the multi-keV temperature regime. At very high densities (over 1000 gcm−3) and temperatures (over 40 keV) we observed chain reactions that reached criticality. These results suggest that there is a case to re-assess the potential of inertial confinement fusion based on deuterium-heavy targets.

Cryogenic solid deuterium target formation to realize highly pure deuteron acceleration by high-intensity laser

In recent years, laser-driven neutron sources have attracted attention for their applications such as nondestructive analysis and the production of medical radioisotopes. One of the efficient neutron production methods is the use of the 9Be(d, n)10B reaction on a beryllium target with deuterons accelerated by laser–plasma interactions, since this is an exothermic reaction. For efficient deuteron acceleration, we have developed a formation system for solid deuterium targets. A millimeter thick solid deuterium target can be formed with the system. Before the laser shot, the solid deuterium target in the laser chamber can be mechanically moved to the laser irradiation point. We have demonstrated deuteron acceleration by the LFEX laser, and a highly pure deuteron pulse with energies of up to 6.2 MeV was measured with a Thomson parabola ion spectrometer.

Measurements of Neutrons Created in a Staged Z-Pinch With Krypton Liner and Deuterium Target at a 1-MA Pulsed Power Generator

Measurements of Neutrons Created in a Staged Z-Pinch With Krypton Liner and Deuterium Target at a 1-MA Pulsed Power Generator

Neutron polarisation transfer, [formula omitted], in π+ photoproduction off the proton, [formula omitted

We report a first measurement of the double-polarisation observable, Cx′, in π+ photoproduction off the proton. The Cx′ double-polarisation observable represents the transfer of polarisation from a circularly polarised photon beam to the recoiling neutron. The MAMI circularly polarised photon beam impinged on a liquid deuterium target cell, with reaction products detected in the Crystal Ball calorimeter. Ancillary apparatus surrounding the target provided tracking, particle identification and determination of recoil nucleon polarisation. The Cx′ observable is determined for photon energies 800-1400 MeV, providing new constraints on models aiming to elucidate the spectrum and properties of nucleon resonances. This is the first determination of any polarisation observable from the beam-recoil group of observables for this reaction. Inclusion of the new data in the database of the SAID partial wave analysis shifted the solution to a new global minima which, not only gives better agreement with the current data, but also improves the description of a range of other single and double polarisation observables for charged pion photoproduction.

Helicity dependent cross sections for the photoproduction of π0π± pairs from quasi-free nucleons

Photoproduction of π0π±-pairs from quasifree nucleons bound in the deuteron has been investigated to study the helicity dependence of this reaction. Measurements with a liquid deuterium target were used to extract the unpolarized cross sections for reactions on protons and neutrons. A deuterated, longitudinally polarized solid-butanol target, together with a circularly polarized photon beam, determined the double polarization observable E. From these results the spin-dependent cross sections σ1/2 and σ3/2, corresponding to the anti-parallel and parallel spin configurations of the beam photon and target nucleon, have been derived. The measurements were performed at the Mainz MAMI accelerator with tagged, circularly-polarized photon beams produced via bremsstrahlung from longitudinally polarized electron beams. The reaction products were detected with an almost 4π solid-angle covering calorimeter composed of the Crystal Ball and TAPS detectors, supplemented by plastic scintillation detectors for charged particle identification. The results are sensitive to sequential decays of nucleon resonances via intermediate states and also to the decay of nucleon resonances by emission of charged ρ mesons, and are compared to recent model results.

Measurement of the T20 component of tensor analyzing power for the incoherent π−-meson photoproduction on a deuteron

We present experimental results for T20 component of the tensor analyzing power for incoherent π− photoproduction on a deuteron. The experiment was performed on an internal tensor-polarized gas deuterium target of the VEPP-3 electron storage ring in 2021 using the proton-proton coincidence method. The data are compared with the results of numerical simulation.

First measurement of polarisation transfer [formula omitted] in deuteron photodisintegration

A first measurement of the polarisation transfer from a circularly-polarised photon to the final state neutron (Cx′n) in deuterium photodisintegration has been carried out. This quantity is determined over the photon energy range 370 – 700 MeV and for neutron centre-of-mass breakup angles ∼45−120∘. The polarisation of the final state neutrons was determined by an ancillary large-acceptance nucleon polarimeter, surrounding a cryogenic liquid deuterium target within the Crystal Ball detector at MAMI. The polarimeter characterised (n,p) charge exchange of the ejected neutrons to determine their polarisation. The new Cx′n data are also compared to a theoretical model based on nucleonic and nucleon resonance degrees of freedom constrained by the current world-database of deuterium photodisintegration measurements. Structures in Cx′n observed in the region of the d⁎(2380) could not be explained by conventional models of deuteron photodisintegration.

Measurement of the T20 Component of the Tensor Analyzing Power of the Incoherent Photoproduction of a π– Meson on a Deuteron

New results have been presented for the T20 component of the tensor analyzing power of the γd → ppπ– reaction measured in the photon energy range from 300 to 600 MeV. The data have been obtained from the statistical sample collected at the VEPP-3 accelerator in 2021. The T20 component has been separated using the asymmetry of the reaction yield, which is due to change in the sign of the tensor polarization of the deuterium target. The experimental data have been compared to the simulation within the spectator model including the interaction between particles in the final state.

Model independent approach to proton polarization in photodisintegration of deuteron

In addition to other photonuclear reactions, the study of photonuclear reactions on deuterium targets is important for laser physics, nuclear physics, astrophysics, and a number of applications, including non-destructive testing of nuclear materials. In this paper, we have carried out a model independent analysis of proton polarization in photodisintegration of deuterons with initially unpolarized beam and unpolarized target. The angular dependence of the polarization is studied by expressing it in terms of multipole amplitudes.

Extraction of ωn , ωp , and ϕN scattering lengths from ω and ϕ differential photoproduction cross sections on a deuterium target

In this study, we try to extract $\ensuremath{\omega}n$, $\ensuremath{\omega}p$, and $\ensuremath{\phi}N$ scattering lengths from the differential cross-section data of near-threshold $\ensuremath{\omega}$ and $\ensuremath{\phi}$ photoproductions at threshold ${t}_{\mathrm{thr}}$. The incoherent data of $\ensuremath{\omega}$ and $\ensuremath{\phi}$ photoproductions on deuterium target for scattering length extractions are provided by the CBELSA/TAPS Collaboration and LEPS Collaboration, respectively, where the deuteron is usually approximated as a weakly bound state of a quasifree neutron plus a quasifree proton. Under the vector meson dominance model and the assumption of energy independence of the differential cross section, we obtained the $|{\ensuremath{\alpha}}_{\ensuremath{\omega}{n}^{*}}|$ and $|{\ensuremath{\alpha}}_{\ensuremath{\omega}{p}^{*}}|$ of loosely bound neutron and proton in the deuteron to be 0.709 $\ifmmode\pm\else\textpm\fi{}$ 0.078 fm and 0.621 $\ifmmode\pm\else\textpm\fi{}$ 0.022 fm, respectively, at threshold ${t}_{\mathrm{thr}}$ for the first time by fitting the near-threshold data of $\ensuremath{\gamma}d$ $\ensuremath{\rightarrow}$ $\ensuremath{\omega}n(p)$ and $\ensuremath{\gamma}d$ $\ensuremath{\rightarrow}$ $\ensuremath{\omega}p(n)$. For a comparison study, we also extracted the scattering length $|{\ensuremath{\alpha}}_{\ensuremath{\omega}p}|$ of the free proton from the $\ensuremath{\omega}$ photoproduction on the hydrogen target by the CBELSA/TAPS Collaboration. With the near-threshold and incoherent $\ensuremath{\phi}$ photoproduction data of $\ensuremath{\gamma}d$ $\ensuremath{\rightarrow}$ $\ensuremath{\phi}pn$ by the LEPS Collaboration, we obtained scattering length $|{\ensuremath{\alpha}}_{\ensuremath{\phi}N}|$ of the bound nucleon inside the deuteron to be 0.109 $\ifmmode\pm\else\textpm\fi{}$ 0.008 fm at threshold ${t}_{\mathrm{thr}}$. The obtained $|{\ensuremath{\alpha}}_{\ensuremath{\omega}p}|$ and $|{\ensuremath{\alpha}}_{\ensuremath{\phi}N}|$ are basically in agreement with the experimental indications and the theoretical predictions within the current uncertainties.

Recoil proton polarization: A new discriminative observable for deeply virtual Compton scattering

Generalized parton distributions describe the correlations between the longitudinal momentum and the transverse position of quarks and gluons in a nucleon. They can be constrained by measuring photon leptoproduction observables, arising from the interference between Bethe-Heitler and deeply virtual Compton scattering (DVCS) processes. At leading-twist/leading-order, the amplitude of the latter is parametrized by complex integrals of the GPDs ${H,E,\stackrel{\texttildelow{}}{H},\stackrel{\texttildelow{}}{E}}$. As data collected on an unpolarized or longitudinally polarized target constrains $H$ and $\stackrel{\texttildelow{}}{H}$, $E$ is poorly known as it requires data collected with a transversely polarized target, which is very challenging to implement in fixed-target experiments. The only alternative considered so far has been DVCS on a neutron with a deuterium target, while assuming isospin symmetry and absence of final-state interactions. Today, we introduce the polarization of the recoil proton as a new DVCS observable, highly sensitive to $E$, which appears feasible for an experimental study at a high-luminosity facility such as Jefferson Lab.

JRC MONNET – the intense fast-neutron source for fundamental and application-driven research

MONNET is a fast-neutron source based on a 3.5 MV tandem accelerator, located at the Geel (BE) site of the Joint esearch Centre. It became operational in 2020. MONNET may deliver intense neutron beams in the energy range from 30 keV to 10.1 MeV and from 12.8 MeV to 24 MeV. Neutrons are generated by means of nuclear reactions in the target material (e.g. protons or deuterons on lithium-7, tritium or deuterium targets). MONNET delivers a neutron flux of up to 109 n/sr/s, depending on the producing reaction and the neutron energy. Neutron beams are essentially mono-energetic (∆En/En < 6% with En > 300 keV). The accelerator may also be used with proton and deuteron beams. Alpha beams will be offered soon. Photon beams are possible and presently under investigation. The research program ranges from cross section measurements, e.g. (n, f), (n, p), (n, α) as well as (p, p′), (p, n) and (p, γ), nuclear fission research, material studies (e.g. radiation-induced damage), to the investigation of advanced methods in nuclear technologies, safety and security. The MONNET neutron source offers beamtime to external user within the JRC EUFRAT Open Access program. Proposal evaluation by an independent panel is taking place up to two times per year.

Ultrashort pulsed neutron source driven by two counter-propagating laser pulses interacting with ultra-thin foil

Neutron production via D(d, n)<sup>3</sup>He nuclear reaction during the interaction of two counter-propagating circularly polarized laser pulses with ultra-thin deuterium target is investigated by particle-in-cell simulation and Monte Carlo method. It is found that the rotation direction and initial relative phase difference of laser electric field vector have important effects on deuterium foil compression and neutron characteristics. The reason is attributed to the net light pressure and the difference in transverse instability development. The highest neutron yield can be obtained by choosing two laser pulses with a relative phase difference of 0 and the same rotation direction of the electric field vector. When the relative phase difference is 0.5π or 1.5π and the rotation direction of electric field vector is different, the neutrons have a directional spatial distribution and the neutron yield only slightly decreases. For left-handed circularly polarized laser pulse and right-handed circularly polarized laser pulse, each with an intensity of 1.23 × 10<sup>21</sup> W/cm<sup>2</sup>, a pulse width of 33 fs and a relative phase difference of 0.5π, it is possible to produce a pulsed neutron source with a yield of 8.5 × 10<sup>4</sup> n, production rate of 1.2 × 10<sup>19</sup> n/s, pulse width of 23 fs and good forward direction as well as tunable spatial distribution. Comparing with photonuclear neutron source and beam target neutron source driven by ultraintense laser pulses, the duration of neutron source in our scheme decreases significantly, thereby possessing many potential applications such as neutron nuclear data measurement. Our scheme offers a possible method to obtain a compact neutron source with short pulse width, high production rate and good forward direction.

Prediction of Neutron Yield in Accelerator Tubes from the Data of Measurements with Test Deuterium Targets on a Disassembling Vacuum Bench

Prediction of Neutron Yield in Accelerator Tubes from the Data of Measurements with Test Deuterium Targets on a Disassembling Vacuum Bench

Measurement of the tensor analyzing power component T20 for the incoherent neutral-pion photoproduction on a deuteron

The paper contains new results for the ${T}_{20}$ component of the tensor analyzing power measured for the incoherent photoproduction of neutral pions on a deuteron, $\ensuremath{\gamma}d\ensuremath{\rightarrow}{\ensuremath{\pi}}^{0}pn$. The results are presented for photon energies ${E}_{\ensuremath{\gamma}}$ in the range from 300 to 600 MeV. The experimental statistics accumulated at the VEPP-3 accelerator complex in 2013 was used. To identify the events, the proton and two $\ensuremath{\gamma}$'s from the ${\ensuremath{\pi}}^{0}\ensuremath{\rightarrow}2\ensuremath{\gamma}$ decay were registered in coincidence. For determination of ${T}_{20}$, the asymmetry of the reaction yield associated with the sign change of the tensor polarization of the deuterium target was measured. The experimental results are compared with theoretical calculations based on the spectator model, including interaction of the final state particles.

Visible-light mediated catalytic asymmetric radical deuteration at non-benzylic positions

Site- and enantioselective incorporation of deuterium into organic compounds is of broad interest in organic synthesis, especially within the pharmaceutical industry. While catalytic approaches relying on two-electron reaction manifolds have allowed for stereoselective delivery of a formal deuteride (D–) or deuteron (D+) at benzylic positions, complementary strategies that make use of one-electron deuterium atom transfer and target non-benzylic positions remain elusive. Here we report a photochemical approach for asymmetric radical deuteration by utilizing readily available peptide- or sugar-derived thiols as the catalyst and inexpensive deuterium oxide as the deuterium source. This metal-free platform enables four types of deuterofunctionalization reactions of exocyclic olefins and allows deuteration at non-benzylic positions with high levels of enantioselectivity and deuterium incorporation. Computational studies reveal that attractive non-covalent interactions are responsible for stereocontrol. We anticipate that our findings will open up new avenues for asymmetric deuteration.

The neutron and proton mass radii from the vector meson photoproduction data on the deuterium target

In this study, we try to extract the mass radii of the neutron and the proton from the differential cross section data of near-threshold $$\omega $$ and $$\phi $$ photoproductions on deuterium target, which is often approximated as a quasi-free neutron plus a quasi-free proton. The incoherent data of $$\omega $$ and $$\phi $$ photoproductions are provided by CBELSA/TAPS collaboration and LEPS collaboration respectively, where the deuteron is disintegrated in the experiments to measure the properties of individual nucleons. Under the VMD model and the assumption of dipole gravitational form factor, we determined the loosely bound neutron and proton mass radii to be $$0.795\pm 0.092\mathrm (stat.)\pm 0.073\mathrm (syst.)$$ fm and $$0.744\pm 0.029\mathrm (stat.)\pm 0.042\mathrm (syst.)$$ fm respectively from the near-threshold data of $$\gamma d \rightarrow \omega n (p)$$ and $$\gamma d \rightarrow \omega p (n)$$ , for the first time. With the near-threshold and incoherent $$\phi $$ photoproduction data of $$\gamma d \rightarrow \phi p n$$ , we determined the average mass radius of the bound nucleon (neutron or proton) inside the deuteron to be $$0.755\pm 0.039\mathrm (stat.)\pm 0.039\mathrm (syst.)$$ fm, for the first time. For a comparison study, we also extracted the mass radius of the free proton from the $$\omega $$ photoproduction on the hydrogen target by CBELSA/TAPS collaboration. Based on our analysis results under the assumptions of VMD model and a low energy QCD theorem, we find that the neutron mass radius is consistent with the proton mass radius within the current statistical uncertainties, and that the nuclear modification on the nucleon mass radius is small inside the deuteron.

Use of Condensed Deuterium and Cryogenic Monodisperse Targets as Loads for Studying Megaampere Z-Pinches

Use of Condensed Deuterium and Cryogenic Monodisperse Targets as Loads for Studying Megaampere Z-Pinches

Use of Bayesian Optimization to understand the structure of nuclei

Monte Carlo simulations are widely used in nuclear physics to model experimental systems. In cases where there are significant unknown quantities, such as energies of states, an iterative process of simulating and fitting is often required to describe experimental data. We describe a Bayesian approach to fitting experimental data, designed for data from a 12Be(d,p) reaction measurement, using simulations made with GEANT4. Q-values from the 12C(d,p) reaction to well-known states in 13C are compared with simulations using BayesOpt. The energies of the states were not included in the simulation to reproduce the situation for 13Be where the states are poorly known. Both cases had low statistics and significant resolution broadening owing to large proton energy losses in the solid deuterium target. Excitation energies of the lowest three excited states in 13C were extracted to better than 90 keV, paving a way for extracting information on 13Be.