Search

Data on the vector analyzing power A y and the tensor analyzing powers A yy , A xx , and A xz in the reaction $\vec d$ d → 3H p at the deuteron energy of 200 MeV are presented over a full angular range in the c.m. frame. The signs of the tensor analyzing powers for forward and backward scattering are found to be sensitive to the D/S wave ratio in 3H and in the deuteron. High-precision experimental data are compared with the results of theoretical calculations performed on the basis of the multiple-scatteringmodel by using standard wave functions for the three-nucleon bound states and for the deuteron.

The data on the vector A y and tensor A yy , A xx , A xz analyzing powers for the $$ \vec d $$ d → 3H p reaction have been obtained at the energy of the initial deuteron of 200MeV in the angular range of 0–95 degrees in the c.m.s. The calculations performed within one-nucleon exchange model with the use of the standard three-nucleon bound state wave functions fail to reproduce the data on the tensor analyzing powers.

The investigation of the spin structure of d, 3H, and 3He has been performed at the RIKEN acceleration research facility and VBLHE. Vector A y and tensor A yy , A xx , A xz analyzing powers for $$ \vec d $$ d → 3Hen and $$ \vec d $$ d → 3Hp are presented at 270 MeV. Themirror channels (3Hen and 3Hp) are comparedto each other in order to find possible manifestation of charge-symmetry breaking. The preliminary results on the polarization observables for $$ \vec d $$ d → 3Hp at 200MeV are also presented. The obtained data are compared with one-nucleon-exchange calculations.As a byproduct, $$ \vec d $$ d → pX and $$ \vec d $$ 12C → pX breakup reactions are investigated at 140, 200, and 270MeV. The experimental data on $$ \vec d $$ p elastic scattering were obtained at 270, 880, and 2000 MeV at the Nuclotron. The polarization of the deuteron beam was measured at 270 MeV at the internal target station. The preliminary data on the vector A y and tensor A yy , A xx analyzing powers for the $$ \vec d $$ p elastic scattering at 880 MeV are presented. The calculations on A y , A yy , and A xx analyzing powers for the $$ \vec d $$ p elastic scattering at 880 MeV were performed in the framework of the multiple-scattering model.

The data on the tensor Ayy, Axx, Axz and vector Ay analyzing powers in the dd->3Hen obtained at Td= 270 MeV in the angular range 0 - 110 degrees in the c.m. are presented. The observed negative sign of the tensor analyzing powers Ayy, Axx and Axz at small angles clearly demonstrate the sensitivity to the ratio of the D and S wave component of the 3He wave function. However, the one-nucleon exchange calculations by using the standard 3He wave functions have failed to reproduce the strong variation of the tensor analyzing powers as a function of the angle in the c.m., Comment: 8 pages, 7 figures, 4 tables. Submitted to EPJA

The 12 C( d ⇒ , α ) 10 B * [2 + ] reaction at 0 ∘ has been proposed as a new tool to calibrate the deuteron beam polarization at intermediate energies. The absolute values of the deuteron polarizations were extracted for the first time by using this reaction at 270 and 140 MeV deuteron energies. The analyzing powers for the d ⇒ –p elastic scattering, which is used as a secondary reaction of a polarimetry, were determined by the new method.

Dibaryons which have a very narrow decay width, called super-narrow dibaryons, are searched for by the p + d scattering at E p = 295 MeV. The experiment was carried out at the Research Center for Nuclear Physics employing a two-arm magnetic spectrometer. A good mass resolution of 0.95 MeV and background free condition have been achieved. No resonance has been observed in the mass region of 1896–1914 MeV. The upper limits of the dibaryon production cross section have been determined.

Cross section, tensor analyzing power T 20 , and vector polarization correlation coefficient C y , y for the 3 He( d , p ) 4 He reaction have been measured at 0° and E d =140, 200, and 270 MeV. The data are compared with a calculation based on an impulse approximation taking the D-state admixtures in deuteron, 3 He, and 4 He explicitly into account. The reasonable agreement with the data is understood as a consequence of a close connection between the 3 He( d , p ) 4 He reaction and the d + N backward scattering.

The cross section, the deuteron vector ${A}_{y}^{d}$ and tensor analyzing powers ${A}_{\mathrm{ij}}$, the polarization transfer coefficients ${K}_{\mathrm{ij}}^{{y}^{\ensuremath{'}}}$, and the induced polarization ${P}^{{y}^{\ensuremath{'}}}$ were measured for the $\mathrm{dp}$ elastic scattering at 270 MeV. The cross section and ${A}_{y}^{d}$ are well reproduced by Faddeev calculations with modern data-equivalent nucleon-nucleon forces plus the Tucson-Melbourne three-nucleon force. In contrast, ${A}_{\mathrm{ij}}$, ${K}_{\mathrm{ij}}^{{y}^{\ensuremath{'}}}$, or ${P}^{{y}^{\ensuremath{'}}}$ are not described by such calculations. These facts indicate the deficiencies in the spin dependence of the Tucson-Melbourne force and call for extended three-nucleon force models.

A complete set of analyzing powers for the $\stackrel{P\vec}{d}d\ensuremath{\rightarrow}{}^{3}\text{H}p$ reaction at the kinetic beam energy of 200 MeV has been measured in the full angular range in the c.m. frame. The observed signs of the tensor analyzing powers ${A}_{yy}$, ${A}_{xx}$, and ${A}_{xz}$ at forward and backward directions have clearly demonstrated the sensitivity to the ratio of the $D$- and $S$-wave components of the triton and deuteron, respectively. The new high-precision data are compared with the prediction of the relativistic multiple-scattering model by using standard wave functions of the three-nucleon bound state and of the deuteron.

Precise measurements of the deuteron to proton polarization transfer coefficients for the d-p elastic scattering have been made at 135 MeV/u at RIKEN Accelerator Research Facility. The obtained results are compared with the Faddeev calculations based on modern nucleon-nucleon forces together with Tucson-Melbourne Tucson-Melbourne' and Urbana–Argonne type of three nucleon forces.

Data for the deuteron analyzing powers in the dd→3Hen(3Hp) reactions obtained at 140–270 MeV are discussed. The observed negative sign of the tensor analyzing powers Ayy, Axx and Axz at small angles clearly demonstrate the sensitivity to the ratio of the D and S state components of the 3He wave function. The behavior of the tensor analyzing powers at backward angles is sensitive to the short‐range spin structure of the deuteron. However, the one‐nucleon exchange calculations using standard 3He and deuteron wave functions fail to reproduce the strong variation of the tensor analyzing powers as a function of angle in the cms. Sensitivity to relativistic effects is also discussed.

Precise measurements of the deuteron to proton polarization transfer coefficients for the d-p elastic scattering has been made at 135 MeV/u at RIKEN Accelerator Research Facility. The obtained results are compared with the Faddeev calculations based on modern nucleon-nucleon forces together with Tucson-Melbourne, Tucson-Melbourne' and Urbana-Argonne type of three nucleon forces.

Dibaryons which have a very narrow decay width, called super-narrow dibaryons, are searched for by the p+d scattering at Ep = 295 MeV . The experiment was carried out at the Research Center for Nuclear Physics employing a two-arm magnetic spectrometer. A good mass resolution of 0.95 MeV and background free condition have been achieved. No resonance has been observed in the mass region of 1896–1914 MeV. The upper limits of the dibaryon production cross section have been determined.

A complete set of polarization transfer coefficients has been measured for the quasi‐elastic 12C(p,n) reaction at a bombarding energy of 345 MeV and laboratory scattering angles of 16°, 22°, and 27°. The spin‐longitudinal IDq and spin‐transverse IDp polarized cross sections are deduced. The theoretically expected enhancement in the spin‐longitudinal mode is observed. The observed IDq is consistent with the pionic enhanced IDq evaluated in a distorted wave impulse approximation (DWIA) calculation employing a random phase approximation (RPA) response function. On the contrary, the theoretically predicted quenching in the spin‐transverse mode is not observed. The observed IDp is not quenched, but rather enhanced in comparison with the DWIA+RPA calculation. Two‐step contributions are responsible in part for the enhancement of ID p.

Precise measurements of the deuteron to proton polarization transfer coefficients for the d‐p elastic scattering has been made at 135 MeV/u at RIKEN Accelerator Research Facility. The obtained results are compared with the Faddeev calculations based on modern nucleon‐nucleon forces together with Tucson‐Melbourne, Tucson‐Melbourne′ and Urbana‐Argonne type of three nucleon forces.

Nucleon-nucleon decoupled dibaryons below the pion emission threshold have been investigated by the $p\stackrel{\ensuremath{\rightarrow}}{d}\mathrm{pdX}$ and $p\stackrel{\ensuremath{\rightarrow}}{d}\mathrm{ppX}$ reactions at ${E}_{p}=300 \mathrm{MeV}.$ Such dibaryons are predicted to either decay into a deuteron or two nucleons by emitting a $\ensuremath{\gamma}$ ray and consequently have a very narrow width of less than 1 keV. The experiment was carried out at the Research Center for Nuclear Physics employing a two-arm magnetic spectrometer. A mass resolution of 0.95 MeV and background-free condition have been achieved. No resonance was found in either the $d+\ensuremath{\gamma}$ or $p+n+\ensuremath{\gamma}$ decay channels within the mass region of 1896\char21{}1914 MeV. Upper limits for the dibaryon production cross section are presented.

Precise measurements of deuteron vector and tensor analyzing powers ${A}_{y}^{d},$ ${A}_{\mathrm{xx}},$ ${A}_{\mathrm{yy}},$ and ${A}_{\mathrm{xz}}$ in $d\ensuremath{-}p$ elastic scattering were performed via ${}^{1}\mathrm{H}(\stackrel{\ensuremath{\rightarrow}}{d},d)p$ and ${}^{1}\mathrm{H}(\stackrel{\ensuremath{\rightarrow}}{d},p)d$ reactions at three incoming deuteron energies of ${E}_{d}^{\mathrm{lab}}=140,$ 200, and $270 \mathrm{MeV}.$ A wide range of center-of-mass angles from $\ensuremath{\approx}10\ifmmode^\circ\else\textdegree\fi{}$ to $180\ifmmode^\circ\else\textdegree\fi{}$ was covered. The cross section was measured at 140 and 270 MeV at the same angles. These high precision data were compared with theoretical predictions based on exact solutions of three-nucleon Faddeev equations and modern nucleon-nucleon potentials combined with three-nucleon forces. Three-body interactions representing a wide range of present day models have been used: the Tucson-Melbourne $2\ensuremath{\pi}$-exchange model, a modification thereof closer to chiral symmetry, the Urbana IX model, and a phenomenological spin-orbit ansatz. Large three-nucleon force effects are predicted, especially at the two higher energies. However, only some of them, predominantly $d\ensuremath{\sigma}/d\ensuremath{\Omega}$ and ${A}_{y}^{d},$ are supported by the present data. For tensor analyzing powers the predicted effects are in drastic conflict to the data, indicating defects of the present day three-nucleon force models.

An (n, p) facility has been constructed at the Research Center for Nuclear Physics. The polarized neutron beam, produced by the 7Li(p,n) reaction, bombards the (n,p) targets placed in the multi-wire drift chamber (MWDC) box. The scattering position is detected by the MWDC and the momentum of the outgoing proton is analyzed by the Large Acceptance Spectrometer (see K. Yako et al. in RCNP annual report 1999). A commissioning run has been performed by using the np scattering. About 2×106/sec neutrons were produced in the target area of 20H×30W (mm2). The typical n-beam polarization was 0.15. The energy resolution of the measurement was 1.4 MeV and the measured differential cross sections are consistent with the known values. By using this facility, the measurement for the 90Zr(n,p)90Y reaction at 300 MeV has been carried out as well as the nd elastic scattering measurement at 250 MeV.

The differential cross sections and vector analyzing powers for the nd elastic scattering at En=250 MeV have been measured at θcm=85°−180°. Our aims are to study the three-nucleon force (3NF) without ambiguities from the Coulomb effect. The data are compared to the results of Faddeev calculations using modern nucleon-nucleon (NN) forces with and without 3NF. It is found that the calculations better reproduce the cross sections by including the 3NF but still underestimate the data.

The 12C(d,α)10B*(2+) reaction at 0° is proposed as a new standard for the deuteron beam polarization at an intermediate energy region. The absolute value of the polarization is measured using this reaction at 270 and 140 MeV deuteron energies for the first time. The obtained beam polarization is used for the calibration of the analyzing powers for the d-p elastic scattering which we use as a polarimetry. The result is almost consistent with the data of the previous calibrations.

A complete set of polarization transfer coefficients has been measured for quasielastic (p,n) reactions on 2H and 12C at a bombarding energy of 346 MeV and laboratory scattering angles of 16°, 22°, and 27°. The spin-longitudinal IDq and spin-transverse IDp polarized cross sections are deduced. The theoretically expected enhancement in the spin-longitudinal mode is observed. The observed IDq is consistent with the pionic enhanced IDq evaluated in a distorted wave impulse approximation (DWIA) calculation employing a random phase approximation (RPA) response function. On the contrary, the theoretically predicted quenching in the spin-transverse mode is not observed. The observed IDp is not quenched, but rather enhanced in comparison with the DWIA+RPA calculation.

Spin-flip probabilities and the differential cross sections for the 26Mg(3He,t)26Al*(1+;1.058 MeV) reaction have been measured at E3He=177 MeV. This is the first spin-flip probability data for the (3He,t) reaction in the energy region above 20 MeV/A. The data are compared with distorted wave Born approximation calculations by using the 3He-n effective interaction extracted from the differential cross sections.

Precise data were obtained for the cross sections as well as the vector and tensor analyzing powers for the deuteron-proton elastic scattering at 270 MeV covering the scattering angles θ cm = 10° – 180°. In addition, the tensor-to-vector polarization transfer coefficients K xx y′ – K yy y′ have been measured for the first time at θ cm = 120°, 130° and 150°. These results have been compared to the Faddeev calculations with and without the three nucleon force.

We have measured the cross sections and the polarization observables for the 3He(d,p)4He reaction at E d =140, 200, and 270 MeV. This work aims to investigate the high momentum component of deuteron D-state wave function and the mechanism for the one-nucleon transfer reaction at intermediate energies. The measurement was carried out by using the spectrograph SMART at RIKEN Accelerator Research Facility. A cryogenic 3He gas target with a density of 6.6×1020 cm−3 was bombarded by a polarized deuteron beam. The data are compared with the calculation based on the one-nucleon exchange approximation.

For backward elastic scattering of deuterons by ${}^{3}\mathrm{He},$ cross sections $\ensuremath{\sigma},$ and tensor analyzing power ${T}_{20}$ are measured at ${E}_{d}=140\ensuremath{-}270$ MeV. The data are analyzed by the plane wave impluse approximation (PWIA) and by the general formula which includes virtual excitations of other channels, with the assumption of the proton transfer from ${}^{3}\mathrm{He}$ to the deuteron. Using ${}^{3}\mathrm{He}$ wave functions calculated by the Faddeev equation, the PWIA describes global features of the experimental data, while the virtual excitation effects are important for quantitative fits to the ${T}_{20}$ data. Theoretical predictions on ${T}_{20},$ ${K}_{y}^{y}$ (polarization transfer coefficient), and ${C}_{\mathrm{yy}}$ (spin correlation coefficient) are provided up to GeV energies.