Recoil Deuterons Research Articles

Measurement of the analyzing powers in vec{p}delastic and vec{p}n quasi-elastic scattering at small angles

.The analyzing powers in proton-deuteron elastic and proton-neutron quasi-elastic scattering have been measured at small angles using a polarized proton beam at the COSY storage ring incident on an unpolarized deuterium target. The data were taken at 796MeV and five higher energies from 1600MeV to 2400MeV. The analyzing power in pd elastic scattering was studied by detecting the low energy recoil deuteron in telescopes placed symmetrically in the COSY plane to the left and right of the beam whereas for pn quasi-elastic scattering a low energy proton was registered in one of the telescopes in coincidence with a fast scattered proton measured in the ANKE magnetic spectrometer. Though the experiment explores new domains, the results are consistent with the limited published information.

Neutron detection and [formula omitted]-ray suppression using artificial neural networks with the liquid scintillators BC-501A and BC-537

In this work we present a comparison between the two liquid scintillators BC-501A and BC-537 in terms of their performance regarding the pulse-shape discrimination between neutrons and γ rays. Special emphasis is put on the application of artificial neural networks. The results show a systematically higher γ-ray rejection ratio for BC-501A compared to BC-537 applying the commonly used charge comparison method. Using the artificial neural network approach the discrimination quality was improved to more than 95% rejection efficiency of γ rays over the energy range 150 to 1000 keV for both BC-501A and BC-537. However, due to the larger light output of BC-501A compared to BC-537, neutrons could be identified in BC-501A using artificial neural networks down to a recoil proton energy of 800 keV compared to a recoil deuteron energy of 1200 keV for BC-537. We conclude that using artificial neural networks it is possible to obtain the same γ-ray rejection quality from both BC-501A and BC-537 for neutrons above a low-energy threshold. This threshold is, however, lower for BC-501A, which is important for nuclear structure spectroscopy experiments of rare reaction channels where low-energy interactions dominates.

Implementation of the foil-on-hohlraum technique for the magnetic recoil spectrometer for time-resolved neutron measurements at the National Ignition Facility.

The next-generation Magnetic Recoil Spectrometer, called MRSt, will provide time-resolved measurements of the deuterium-tritium-neutron spectrum from inertial confinement fusion implosions at the National Ignition Facility. These measurements will provide critical information about the time evolution of the fuel assembly, hot-spot formation, and nuclear burn. The absolute neutron spectrum in the energy range of 12-16 MeV will be measured with high accuracy (∼5%), unprecedented energy resolution (∼100 keV) and, for the first time ever, time resolution (∼20 ps). Crucial to the design of the system is a CD conversion foil for the production of recoil deuterons positioned as close to the implosion as possible. The foil-on-hohlraum technique has been demonstrated by placing a 1-mm-diameter, 40-μm-thick CD foil on the hohlraum diagnostic band along the line-of-sight of the current time-integrated MRS system, which measured the recoil deuterons. In addition to providing validation of the foil-on-hohlraum technique for the MRSt design, substantial improvement of the MRS energy resolution has been demonstrated.

A New Measurement of 11Be(p,d) Transfer Reaction**Supported by the National Key Research and Development Program of China under Grant No 2018YFA0404403, and the National Natural Science Foundation of China under Grant Nos 11775004 and 11775036.

A new 11Be(p,d) transfer reaction experiment is performed in inverse kinematics with a radioactive 11Be beam at 26.9A MeV. Three low-lying states, namely the 0+ ground state, the 2+ state at Ex = 3.37 MeV, and the multiplet at around 6 MeV in 10Be, are populated by this one-neutron transfer reaction. These three states in 10Be are clearly discriminated from the Q-value spectrum, which is rebuilt from energies and angles of the recoil deuterons in coincidence with 10Be. A spectroscopic factor for each state is extracted by comparing the experimental differential cross sections to the theoretical calculation results using the finite range adiabatic distorted wave approximation method with different global nucleon-nucleus potentials. It is found that the newly extracted spectroscopic factors for the 0+ and 2+ states are consistent with the previous ones, but the factor for the multiplet is smaller than the value in the reference, and the possible reason is discussed.

Radiative corrections to polarization observables in elastic electron-deuteron scattering in leptonic variables

The model-independent QED radiative corrections to polarization observables in elastic scattering of unpolarized and longitudinally polarized electron beams by a deuteron target are calculated in leptonic variables. The experimental setup when the deuteron target is arbitrarily polarized is considered and the procedure for applying the derived results to the vector or tensor polarization of the recoil deuteron is discussed. The calculation is based on taking all essential Feynman diagrams into account, which results in the form of the Drell-Yan representation for the cross section, and the use of the covariant parameterization of the deuteron polarization state. Numerical estimates of the radiative corrections are given in the case where event selection allows undetected particles (photons and electron-positron pairs) and the restriction on the lost invariant mass is used.

Photoproduction of mesons off the deuteron: quasifree and coherent processes

Photoproduction of mesons off the deuteron has been investigated at a tagged photon beam of the Bonn ELSA accelerator with the combined Crystal Barrel - TAPS electromagnetic calorimeter for incident photon energies up to 2.5 GeV. The mesons have been detected in coincidence with recoil protons, neutrons and deuterons. This allow the measurement of meson production reactions off the quasifree nucleons bound in the deutron, as well as the coherent production off the deuteron. The comparison of quasifree proton reactions to free proton reactions can confirm or invalidate possible nuclear effects on the extracted cross section reactions. Furthermore the isospin composition of a resonance can be estimated from the comparison of quasifree proton and neutron reactions. The quasifree photoproduction of the η″ and π°η mesons off nucleons and the coherent photoproduction of π°η–pairs off the deuteron are discussed.

Experimental study of 4H in the reactions 2H(t, p) and 3H(t, d)

The 4H resonance was investigated in the transfer reactions 2H(t,p)4H and 3H(t,d)4H using cryogenic liquid targets of deuterium and tritium and 58 MeV triton beam. The multidetector system with a large angular acceptance was used to measure the recoil protons and deuterons in coincidences with tritons or neutrons from the decay of 4H. Data analysis involved careful considerations made for the competing processes of final state interaction and quasifree scattering. The experimental data show a peak with resonance parameters Eres=3.05±0.19 MeV and Γobs=4.18±1.02 MeV. The pole of S-matrix corresponding to the physical values of energy and width, E0=1.99±0.37 MeV and Γ0=2.85±0.3 MeV, has been extracted.

A Method of Measuring Hydrogen Isotopes in Surface Layers of Planetary Soils by Spectroscopy of Recoil Protons in Alpha Particle Elastic Scattering

A theoretical and experimental feasibility study of possible determination of the hydrogen and deuterium concentrations in the surface layers of planetary bodies is presented. The method under study is the recoil proton and deuteron spectrometry of forward scattering in the course of elastic interaction of alpha particles with the nuclei of hydrogen isotopes. The spectra of recoil protons and deuterons were recorded using a prototype model of a hydrogen spectrometer, and these spectra were used to determine the hydrogen concentrations in the samples of different compositions.

Exclusive measurement of coherent η-photoproduction from the deuteron

Coherent photoproduction of eta mesons from the deuteron has been measured from threshold up to incident photon energies of 750 MeV using the photon spectrometer TAPS at the tagged photon facility at the Mainz microtron MAMI. For the first time, differential coherent cross sections have been deduced from the coincident detection of the eta meson and the recoil deuteron. A missing energy analysis was used for the suppression of background events so that a very clean identification of coherent eta-photoproduction was achieved. The resulting cross sections agree with previous experimental results except for angles around 90 deg in the photon-deuteron cm-system where they are smaller. They are compared to various model calculations.

A neutron spectrometer for precise measurements of DT neutrons from 10 to 18 MeV at OMEGA and the National Ignition Facility

A model independent method to determine fuel 〈ρR〉 is to measure the energy spectrum and yield of elastically scattered primary neutrons in deuterium–tritium (DT) plasmas. As is the case for complementary methods to measure fuel 〈ρR〉 (in particular from knock-on deuterons and tritons [S. Skupsky and S. Kacenjar, J. Appl. Phys. 52, 2608 (1981); C. K. Li et al. (unpublished)]), minimizing the background is critical for successful implementation. To achieve this objective, a novel spectrometer for measurements of neutrons in the energy range 10–18 MeV is proposed. From scattered neutrons (10–13 MeV), the DT fuel 〈ρR〉 will be measured; from primary neutrons (∼14 MeV), the ion temperature and neutron yield will be determined; and from secondary neutrons, in the energy range 12–18 MeV, the fuel 〈ρR〉 in deuterium plasmas will be inferred at the National Ignition Facility. The instrument is based on a magnetic spectrometer with a neutron-to-deuteron (nd) conversion foil for production of deuteron recoils at nearly forward scattered angles. In its initial phase of implementation, CR-39 track detectors will be used in the focal plane to detect the recoil deuterons with extremely high spatial resolution. Besides simplicity, CR-39 track detectors will facilitate a highly accurate energy calibration. However, in a later implementation of the spectrometer design, the recoils will also be detected by an array of fast scintillation counters functioning in current mode. In either detection scheme, the detection efficiency is about 10−9 for measuring 14 MeV neutrons with an energy resolution of about 3%. Due to its large dynamic range, its relatively high efficiency, and a compliant design that allows for significant background rejection, this spectrometer can be effectively used, with very high resolution, at both OMEGA and the National Ignition Facility.

Measurement of tensor polarization in elastic electron-deuteron scattering at large momentum transfer

Tensor polarization observables ( t(20), t(21), and t(22)) have been measured in elastic electron-deuteron scattering for six values of momentum transfer between 0.66 and 1.7 (GeV/c)(2). The experiment was performed at the Jefferson Laboratory in Hall C using the electron High Momentum Spectrometer, a specially designed deuteron magnetic channel and the recoil deuteron polarimeter POLDER. The new data determine to much larger Q2 the deuteron charge form factors G(C) and G(Q). They are in good agreement with relativistic calculations and disagree with perturbative QCD predictions.

Tensor polarization in elastic electron-deuteron scattering to the highest possible momentum transfers

In elastic electron-deuteron scattering, the tensor polarization moments t 20 , t 21 and t 22 , together with the unpolarized cross-sections, have been measured up to a momentum transfer of 1.8 (GeV/c) 2 , or 6.8 fm −1 . The experiment was performed at Jefferson Laboratory using the recoil deuteron polarimeter POLDER. Preliminary results are presented and discussed, especially in view of their significance concerning the applicability of perturbative QCD to this exclusive process.

RBS analysis of deuterium distribution with coincidence detection of recoil particles

A novel analytical method of deuterium depth distribution is presented for a film target with thickness exceeding a few μm. The method is based on the Rutherford Backscattering Spectroscopy (RBS) combined with the Elastic Recoil Detection (ERD). The scattered protons are detected coincidentally with the recoil deuterons to eliminate protons scattered by substrate and impurity atoms. Energy of the coincident protons is then analyzed to deduce the deuterium distribution. Results of proof-of-principle experiments using a deuterated polyethylene film and a deuterium implanted titanium sample are presented, and effect of multiple scattering is discussed. The present method is applicable for targets with thickness of several μm which cannot be reached by conventional heavy-ion ERD using MV accelerators, and has an advantage that we can avoid deformation of hydrogen isotope distribution caused by irradiation of heavy ions.

Coherent vector meson production from deuterons

In this paper we discuss coherent photo- and leptoproduction of vector mesons from deuterons at intermediate (virtual) photon energies, 3 ≤ν≤ 30 GeV. We consider the scattering from unpolarized and polarized targets as well as processes where the polarization of the recoil deuteron is measured. Our main motivation results from the need for a quantitative analysis of the space-time structure of photon-induced processes. In this respect we suggest several possibilities to explore the characteristic longitudinal interaction length in coherent vector meson production. Furthermore, we outline methods for an investigation of color coherence effects. Besides the presentation of benchmark values for the maximal possible color coherence effect in various kinematic regions, we illustrate the anticipated phenomena within the color diffusion model. Finally we recall that the determination of vector meson-nucleon cross sections is not a closed issue. Besides being not known to a satisfying accuracy, they can be used to determine the strength of the D-state in low mass vector mesons.

Measurement of tensor polarization observables in the [formula omitted] reaction between 580 and 1300 MeV

During the last decade, our understanding of the πNN system has been improved with the measurement of double polarization observables [1]. In this experiment the recoil deuteron polarization produced in the H( p, d)π + reaction was measured with the POLDER polarimeter for incident protons of kinetic energies between 580 and 1300 MeV.

Differential cross sections for np → dX at 1.0 and 2.0 GeV

Inclusive deuteron spectra ( d 2σ dΩdp ) have been measured for the reaction np → dX at neutron energies of 1.0 and 2.0 GeV. A quasi-monochromatic neutron beam was used, along with a liquid hydrogen target. Recoil deuterons at laboratory angles from 3° to 15° were tracked in wire chambers surrounding a 1.5 T·m dipole magnetic field. Particle identification was achieved using time-of-flight and momentum measurements. The deuteron data are compared with the predictions of a one-nucleon-exchange model with σ meson production. At 2 GeV the missing mass spectra suggest the large role played by both the η and ϱ mesons in deuteron production.

Resolution of discrepancy between backward angle cross-section data for neutron-deuteron elastic scattering

High-accuracy differential cross-section data for neutron-deuteron elastic scattering at centre-of-mass backward angles in the range from 140° to 178° have been measured to accuracies better than ±3% for incident neutron energies of 8.0, 10.0, and 14.0 MeV. The measurements were made by detection of the recoil deuterons and protons from a mixed CD2-CH2 foil. The new data are compared to existing data and to three-nucleon calculations with the Bonn-B nucleon-nucleon potential. We conclude that the present measurements unambiguously resolve the discrepancies among previously reported data of the same type.

Analyzing power in neutron-deuteron elastic scattering at Elabn=3 MeV.

A measurement of the analyzing power ${\mathit{A}}_{\mathit{y}}$(\ensuremath{\theta}) in neutron-deuteron (n-d) elastic scattering below the deuteron breakup threshold is described, including a detailed discussion of the experimental apparatus and the treatment of systematic errors. The data provide a precise test of Faddeev calculations of the three-nucleon system and of the nucleon-nucleon interaction models used as inputs to these calculations. ${\mathit{A}}_{\mathit{y}}$ was measured at six angles from 44.5 \ifmmode^\circ\else\textdegree\fi{} c.m. to 145.7 \ifmmode^\circ\else\textdegree\fi{} c.m. to a precision of (7--13)\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}4}$. Polarized neutrons, produced by the $^{3}\mathrm{H}$(p\ensuremath{\rightarrow},n\ensuremath{\rightarrow}${)}^{3}$He reaction, were incident upon the target, a deuterated organic scintillator. Scattered neutrons were detected in fast coincidence with the recoil deuterons in the target. A computer simulation of the experiment was used to compensate for a number of systematic errors. Particularly important were corrections for neutron multiple scattering, accidental coincidences, and finite geometry effects. The ${\mathit{A}}_{\mathit{y}}$ data have a 2.2% scale factor uncertainty associated with uncertainty in the polarization of the incident neutron beam. The incident neutron polarization was measured in a separate experiment using n${\mathrm{\ensuremath{-}}}^{4}$He scattering from a liquid helium scintillator. The neutron polarization measurement also yielded an improved value for the polarization transfer coefficient [${\mathit{K}}_{\mathit{y}}^{\mathit{y}}$(${0}^{\mathrm{\ifmmode^\circ\else\textdegree\fi{}}}$)=0.650\ifmmode\pm\else\textpm\fi{}0.019] in the $^{3}\mathrm{H}$(p\ensuremath{\rightarrow},n\ensuremath{\rightarrow}${)}^{3}$He reaction at ${\mathit{E}}_{\mathrm{lab}}^{\mathit{p}}$=3.80 MeV. A comparison of the ${\mathit{A}}_{\mathit{y}}$ data to Faddeev calculations shows that the discrepancy in ${\mathit{A}}_{\mathit{y}}$ observed previously at higher energies continues below the breakup threshold. A comparsion of the ${\mathit{A}}_{\mathit{y}}$ data to a recent phase shift analysis of proton-deuteron (p-d) scattering indicates that observed differences between n-d and p-d analyzing powers are only partially explained by Coulomb effects.

Tensor polarization in elastic electron-deuteron scattering in the momentum transfer range 3.8

The tensor polarization of the recoil deuteron in elastic electron-deuteron scattering has been measured at the Bates Linear Accelerator Center at three values of four-momentum transfer [ital Q]=3.78, 4.22, and 4.62 fm[sup [minus]1], corresponding to incident electron energies of 653, 755, and 853 MeV. The scattered electrons and the recoil deuterons were detected in coincidence. The recoil deuterons were transported to a liquid hydrogen target to undergo a second scattering. The angular distribution of the [ital [rvec d]]-[ital p] scattering was measured using a polarimeter. The polarimeter was calibrated in an auxiliary experiment using a polarized deuteron beam at the Laboratoire National Saturne. A Monte Carlo procedure was used to generate interpolated calibration data because the energy spread in the deuteron energies in the Bates experiment spanned the range of deuteron energies in the calibration experiment. The extracted values of [ital t][sub 20] are compared to predictions of different theoretical models of the electromagnetic form factors of the deuteron: nonrelativistic and relativistic nucleon-meson dynamics, Skyrme model, quark models, and perturbative quantum chromodynamics. Along with the world data the structure functions [ital A]([ital Q]) and [ital B]([ital Q]) are used to separate the charge monopole and charge quadrupole form factors ofmore » the deuteron. A node in the charge monopole form factor is observed at [ital Q]=4.39[plus minus]0.16 fm[sup [minus]1].« less

Absolute differential cross sections and charge asymmetries for pi +/-d elastic scattering at 30, 50, and 65 MeV.

Absolute ${\mathrm{\ensuremath{\pi}}}^{\ifmmode\pm\else\textpm\fi{}}$d differential cross sections and charge asymmetries have been measured at incident pion energies of 30 and 50 MeV, using an active target of scintillator plastic to detect recoil deuterons in coincidence with scattered pions. In addition, a small set of data at 65 MeV was collected for comparision with the results of an earlier experiment performed by this group. Measurements at 50 MeV from the earlier experiment are compared with the results of the present experiment.