Search

We present a precise measurement of the cross section, proton and $\rm ^3He$ analyzing powers, and spin correlation coefficient $C_{y,y}$ for $p$-$\rm ^3He$ elastic scattering near 65 MeV, and a comparison with rigorous four-nucleon scattering calculations based on realistic nuclear potentials and a model with $\Delta$-isobar excitation. Clear discrepancies are seen in some of the measured observables in the regime around the cross section minimum. Theoretical predictions using scaling relations between the calculated cross section and the $\rm ^3 He$ binding energy are not successful in reproducing the data. Large sensitivity to the $NN$ potentials and rather small $\Delta$-isobar effects in the calculated cross section are noticed as different features from those in the deuteron-proton elastic scattering. The results obtained above indicate that $p$-$\rm ^3He$ scattering at intermediate energies is an excellent tool to explore nuclear interactions not accessible by three-nucleon scattering., Comment: 22 pages, 6 figures

We measured the cross section and the proton analyzing power A_yAy for pp–^33He elastic scattering at the angles \theta = 26.9^{\circ}θ=26.9∘–170.1^{\circ}170.1∘ in the center of mass system with a 65 MeV polarized proton beam. We compared the data with the rigorous numerical calculations based on the various nucleon–nucleon potentials. For the cross section, clear discrepancy is seen at the angles where the cross section takes minimum. For the proton analyzing power A_yAy, the calculations have moderate agreements with the data. In this proceedings, we show only the experimental results.

We performed the measurement of the cross section and the proton analyzing power \(A_y\) for p–\(^3\)He elastic scattering with a 65 MeV polarized proton beam at Research Center for Nuclear Physics (RCNP), Osaka University. The proton analyzing power \(A_y\) data are compared with the theoretical calculations based on the nucleon–nucleon potential (INOY04).

A set of differential cross-section data of the 1 H(d, pp)n breakup reaction at 130 MeV deuteron beam energy has been measured in the domain of very forward polar angles with the use of the Germanium Wall detector at the Forschungszentrum Julich. The data obtained for over 1000 kinematical points (112 geometries) are compared with the theoretical predictions based on various models of the three-nucleon (3N) dynamics. They comprise: the realistic nucleon-nucleon potentials alone or combined with the three-nucleon force (3NF), the coupled-channel calculations with the explicit treatment of the Δ-isobar excitation and finally, the potentials derived from chiral perturbation theory. In the part of the phase space studied, the Coulomb interaction between protons has a strong impact on the differential cross section of the breakup reaction. The strongest Coulomb effects are found in regions where the relative energy of the two protons is the smallest. In these regions the data are well reproduced exclusively by calculations which include the electromagnetic repulsion between protons. In spite of the dominance of the Coulomb force in the phase space studied, the contribution of 3NF effects is also observed.

We have measured a complete set of deuteron analyzing powers in deuteron–proton elastic scattering at 190, 250, and 294 MeV/nucleon. The obtained data are compared with the Faddeev calculations based on the modern nucleon–nucleon forces together with the Tucson-Melbourne’99, and UrbanaIX three nucleon forces. The data are also presented with the calculations based on the N4LO NN potentials of the chiral effective field theory.

We have measured all deuteron analyzing powers \({(A_{y}^{d}, A_{yy}, A_{xx}, A_{xz})}\) for deuteron-proton elastic scattering at 294 MeV/nucleon in order to study the properties of three nucleon forces (3 NFs). Measurement was made at in an angular range of \({\theta_{{\rm c.m.}} = 35.6^{\circ} - 163.0^{\circ}}\). Obtained data were compared with Faddeev calculations with and without the 3 NFs. At \({\theta_{{\rm c.m.}}\lesssim 120^{\circ}}\) all the data have general agreement with the calculations, while the measured data at \({\theta_{{\rm c.m.}} \gtrsim 120^{\circ}}\) are not explained by any theoretical calculations. These results were consistent with those at 250 MeV/nucleon.

With the aim of clarifying roles of the 3NFs in nuclei experimental programs with the polarized deuteron beam at intermediate energies are in progress at RIKEN RI Beam Factory. As the first step, we have measured a complete set of deuteron analyzing powers in deuteron–proton elastic scattering at 250 and 294 MeV/nucleon. The obtained data are compared with the Faddeev calculations based on the modern nucleon–nucleon forces together with the Tucson–Melbourne’99, and UrbanaIX three nucleon forces.

The review of the recent results on spin effects in few nucleon systems obtained at LHEP-JINR are presented. The data on the deuteron analyzing powers in different reactions in the wide energy range demonstrate the sensitivity to the spin structure of the light nuclei. The future plans on the studies with polarized deuterons from new polarized ion source at Nuclotron will be reported.

Recent results on the spin effects in deuteron inclusive breakup and deuteron-proton elastic scattering obtained at the Veksler and Baldin Laboratory of High Energies at JINR are reported. The experimental data have been obtained with the use of a high-energy polarized deuteron beam at the Synchrophasotron-Nuclotron Accelerator Complex. The covered energy range corresponds to the short internucleonic distances where the relativistic effects and non-nucleonic degrees of freedom can play a significant role.

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 preliminary results on the angular distributions of the vector A y and tensor A yy , A xx analyzing powers in dp elastic scattering at T d = 880MeV are presented. A region of center-of-mass system angles from 60° to 140° is covered. The experimental data are compared with the preliminary calculations obtained within framework of different theoretical approaches. The experiment has been performed at the Internal Target Station at Nuclotron within the framework of the program on the study of light nuclei spin structure proposed at JINR (Russia) and RIBF (Japan).

Recent experimental progress of the three-nucleon force study is shown placing an emphasis on the nucleon-deuteron elastic scattering at intermediate energies.

The cross sections and spin observables of the pd elastic scattering have been measured at 392 MeV. The results are compared with the prediction of Faddeev calculations with and without including a three nucleon force.

The differential cross sections and the vector analyzing powers for the nd elastic scattering at E n = 250 MeV have been measured for the study of the three-nucleon force (3NF) effects in the Coulomb-free system. To cover a wide angular region, the experiments were performed by using two different methods at the ( n , p ) facility and at the NTOF facility which constructed at the Research Center for Nuclear Physics (RCNP). The results were compared with theoretical predictions of the Faddeev calculations based on the modern nucleon-nucleon (NN) forces with the three-nucleon force (3NF). The inclusion of 3NFs leads to a good description of the cross section except for the backward angles. The results were also compared with the theoretical predictions with relativistic corrections. The direct data-to-data comparison of the cross sections of the nd and pd was performed.

Extensive studies of three-nucleon force (3NF) effects in elastic proton-deuteron scattering have been performed at KVI and elsewhere in the past. In the present work, we explored 3NF effects in the break-up scattering process by performing high precision measurement of vector analyzing powers and differential cross sections using a 190 MeV polarized-proton beam on a liquid deuterium target. The experiment was performed by exploiting a new detector called Big Instrument for Nuclear-polarization Analysis, BINA. Its unique design enables coverage of almost the complete reaction phase space. Preliminary differential cross sections and vector analyzing powers are presented and results are compared with state-of-the-art three-nucleon calculations.

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.

With the aim of clarifying roles of the 3NFs in nuclei experimental programs with the polarized deuteron beam at intermediate energies are in progress at RIKEN RI Beam Factory. As the first step, we have measured a complete set of deuteron analyzing powers in deuteron–proton elastic scattering at 250 and 294 MeV/nucleon. The obtained data are compared with the Faddeev calculations based on the modern nucleon–nucleon forces together with the Tucson–Melbourne’99, and UrbanaIX three nucleon forces.

A new high-energy beam polarimeter is proposed for Nuclotron, which uses the Internal Target Station (ITS). This polarimeter based on a measurement of asymmetry for the d–p elastic scattering will allow one to measure simultaneously both vector and tensor components of deuteron beam polarization. For this purpose an analyzing powers measurement for the d–p elastic scattering at energies T d = 0.88–2 GeV is proposed. The precise measurements of the deuteron analyzing powers over the energy range T d = 300–2000 MeV can give an irreplaceable clue to the study of the spin dependence of three nucleon forces.

The neutron–deuteron ( n d ) elastic scattering differential cross section has been measured at 95 MeV incident neutron energy. The neutron–proton ( n p ) differential cross section has also been measured for normalization purposes. An inclusion of three-nucleon forces gives a considerable improvement in the theoretical description of the nd data in the angular region of the cross-section minimum.

A polarized proton solid target has been developed at the Center for Nuclear Study, the University of Tokyo. The polarized target makes use of a large population difference among Zeeman sub-levels in the photo-excited triplet state of pentacene. We have successfully applied this polarized target to the first RI beam experiment, where a vector analyzing power for the proton- 6 He elastic scattering has been measured.

Several examples of recent experimental activities in Japan on the study of three-nucleon-force (3NF) effect via the nucleon-deuteron (Nd) elastic scattering at intermediate energies are reviewed. Discrepancies between the data and theoretical predictions are identified.

We have measured angular distributions of the differential cross-section, the analyzing power and all of the spin transfer coefficients K y y′ , K x x′ , K z x′ , K x z′ , and K z z′ for the pd elastic scattering at 250 MeV. These are the first measurements of a complete set of proton polarization observables for pd elastic scattering at intermediate energies. The present data are compared with theoretical predictions based on exact solutions of the three-nucleon Faddeev equations and modern realistic nucleon-nucleon potentials combined with three-nucleon forces (3NF), namely the Tucson-Melbourne (TM) 2π-exchange model, a modification thereof (TM′) closer to chiral symmetry, and the Urbana IX model.

Several examples of recent experimental activities in Japan on the study of three-nucleon-force effects via the Nd elastic scattering at intermediate energies are briefly reviewed. Differences between the data and theoretical predictions are identified.

To study the three-nucleon force (3NF) effects without ambiguities from the Coulomb effect, the differential cross sections and the vector analyzing powers for the [Formula: see text] elastic scattering at En = 245 MeV have been measured at θcm = 85° - 180°. The data are compared to the results of Faddeev calculations using modern nucleon-nucleon (NN) forces with and without 3NF. Additionally we have a plan to extend our measurement to the forward angular region where the Coulomb effect is expected to be large. We carried out the test experiment and measured the differential cross sections at θcm = 21°.

The cross sections and spin observables of the p+d elastic scattering have been measured at 392 MeV. The results are compared with the results of Faddeev calculations with and without including the three nucleon force.

The angular distributions of the cross section, the proton analyzing power and all of proton polarization transfer coefficients of [Formula: see text] elastic scattering were measured at 250 MeV. The present data are compared with theoretical predictions based on exact solutions of the three-nucleon Faddeev equations and modern realistic nucleon-nucleon potentials combined with three-nucleon forces. These results call for a better understanding of the spin structure of the three-nucleon force and very likely for a full relativistic treatment of the three-nucleon continuum.

Thick deuterated polyethylene (CD2) targets were produced by heating and pressing the CD2 powder. The thickness of the CD2 targets are from 24 to 560 mg / cm 2 . The uniformity of the target thickness is ±20 μm (2.2 mg / cm 2 ) . These targets were used as deuteron targets in the measurement of the n → +d elastic scattering at E n → =245 MeV .

New polarimeter based on the asymmetry measurement in dp-elastic scattering has been constructed at internal target at Nuclotron (JINR). The result on the deuteron analyzing powers Ay, Ayy and Axx in the deuteron-proton (dp) elastic scattering at the energies of 880 and 2000 MeV are presented. They are compared with different theoretical approaches.

A complete high-precision set of deuteron analyzing powers for elastic deuteron-proton (dp) scattering at 250 and 294 MeV/nucleon has been measured. These data and previously existing data sets for the cross section at similar energies are compared to the results of three-nucleon Faddeev calculations based on modern nucleon-nucleon (NN) potentials alone or combined with two models of three-nucleon forces: the Tucson-Melbourne 99 and Urbana IX. Large discrepancies between pure NN theory and data, which are not resolved by the current three-nucleon forces, were found at c.m. backward angles θc.m.≳120∘ for all the deuteron analyzing powers and the cross section. Because only small relativistic effects were found for the deuteron analyzing powers and the cross section, the inclusion of short-range components of the three-nucleon force is probably required to get a better description of the data.

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.

New vector analyzing-power data on (p) over right arrow+ d elastic scattering at E-p = 150 and 190 MeV have been measured. These an presented together with existing data and with recent (d) over right arrow + p vector and tensor analyzing power data at E-d = 270 MeV. The strong negative extremum of both vector analyzing powers A(y)(p) and A(y)(d) at theta(c.m.) similar or equal to 80 degrees-120 degrees is underestimated by Faddeev calculations using modern NN forces. Inclusion of the Tucson-Melbourne 3N force shifts the minima upwards, but with conflicting results for p A(y)(p), and leading to a good description for A(y)(d). An A(y)(p) puzzle, previously thought to exist at energies E-N less than or equal to 30 MeV only, appears to exist also at intermediate energies.

Vector analyzing powers for proton elastic scattering from 8He at 71 MeV/nucleon have been measured using a solid polarized proton target operated in a low magnetic field of 0.1 T. The spin-orbit potential obtained from a phenomenological optical model analysis is found to be significantly shallower and more diffuse than the global systematics of stable nuclei, which is an indication that the spin-orbit potential is modified for scattering involving neutron-rich nuclei. A close similarity between the matter radius and the root-mean-square radius of the spin-orbit potential is also identified., Comment: 6 pages, 4 figures, accepted for publication in Physical Review C Rapid Communication

The differential cross sections and the vector and tensor analyzing powers Ay, Ayy, Axx, and Axz for the d-p elastic scattering were measured at Edlab = 270 MeV over the c.m. angular range from 57° to 138°. The data are compared with a Faddeev calculation. A good description is obtained for all components of the analyzing powers, while a discrepancy of about 30% is found in the cross section around θc.m. = 120°.

Recent results on spin effects in few nucleon systems obtained at Nuclotron-JINR are presented. The data on the deuteron analyzing powers in different reactions in the wide energy range demonstrate the sensitivity to the short-range spin structure of the light nuclei. The future plans on the studies with polarized deuterons from new polarized ion source at Nuclotron will be reported.

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.

The vector Ay and tensor analyzing powers Ayy and Axx for dp- elastic scattering were measured at Td = 880 MeV over the c.m. angular range from 60 to 140 degrees at the JINR Nuclotron. The data are compared with predictions of different theoretical models based on the use of nucleon-nucleon forces only. The observed discrepancies of the measured analyzing powers from the calculations require the consideration of additional mechanisms., Comment: 5 pages,3 figures

Set of vector analyzing power data of the (d) over barp elastic scattering and H-1((d) over bar, pp)n breakup reactions at 130-MeV deuteron beam energy has been measured in the domain of very forward polar angles. The results are compared with theoretical predictions originating from various approaches: realistic nucleon-nucleon (NN) potentials and the NN potentials combined with a three-nucleon force (3NF) model and with predictions based on the ChPT framework. In case of the breakup process, none of the theoretical calculations reveal sensitivity to any of the dynamical effects such as 3NF or Coulomb interaction and they describe the experimental data equally well. For the elastic scattering, the Coulomb correction appears not negligible at very small theta(c.m.)(d). The effect seems to be confirmed by the data.

The quasi-elastic scattering (QES) process has been studied for the ( p , n ) reaction at 300 and 400 MeV. Energy spectra for targets ranging from 2 H to nat Pb have been obtained for a wide range of scattering angles corresponding to momentum transfers q = 1.0 – 2.4 fm −1 . Energy shift of the QES peak from that of 2 H to higher excitation energy is observed for all targets studied, with a gradual increase with target mass reaching almost a constant value of ∼26 MeV beyond 12 C. The mass dependence oo the effective neutron number ( N eff ) for the ( p , n ) QFS process is well represented by N eff = 0.85 N 0.5 over a wide mass range from 2 H to nat Pb except for 6 Li, 7 Li and 9 Be which deviate significantly. The analyzing powers of the QES peak region for the 12 C and 40 Ca targets are compared to those of the 2 H( p , n ) reaction at 300 and 400 MeV and found to be almost identical for q ≤ 1.5 fm −1 . Transverse polarization transfer coefficients at 0 degree D NN (0°) have been measured for the 1p shell nuclei at 300 MeV. Large negative D NN (0°) values are observed for the continuum region up to an excitation energy of 50 MeV irrespective of targets. The D NN (0°) values observed for the GT transitions are around −0.28 which indicates the contribution from the tensor interactions. The DWIA calculations well reproduce the observed D NN (0°) values.

The vector analyzing power has been measured for the elastic scattering of neutron-rich 6He from polarized protons at 71 MeV/nucleon making use of a newly constructed solid polarized proton target operated in a low magnetic field and at high temperature. Two approaches based on local one-body potentials were applied to investigate the spin-orbit interaction between a proton and a 6He nucleus. An optical model analysis revealed that the spin-orbit potential for 6He is characterized by a shallow and long-ranged shape compared with the global systematics of stable nuclei. A semimicroscopic analysis with a alpha+n+n cluster folding model suggests that the interaction between a proton and the alpha core is essentially important in describing the p+6He elastic scattering. The data are also compared with fully microscopic analyses using non-local optical potentials based on nucleon-nucleon g-matrices., 20 pages, 20 figures, accepted by Physical Review C

A complete high precision set of deuteron analyzing powers for elastic deuteron-proton ($dp$) scattering at 250 MeV/nucleon (MeV/N) has been measured. The new data are presented together with data from previous measurements at 70, 100, 135 and 200 MeV/N. They are compared with the results of three-nucleon (3N) Faddeev calculations based on modern nucleon-nucleon (NN) potentials alone or combined with two models of three nucleon forces (3NFs): the Tucson-Melbourne 99 (TM99) and Urbana IX. At 250 MeV/N large discrepancies between pure NN models and data, which are not resolved by including 3NFs, were found at c.m.\ backward angles of $\theta_{\rm c.m.}\gtrsim 120^\circ$ for almost all the deuteron analyzing powers. These discrepancies are quite similar to those found for the cross section at the same energy. We found small relativistic effects that cannot resolve the discrepancies with the data indicating that other, short-ranged 3NFs are required to obtain a proper description of the data., Comment: submitted to Phys. Rev. C

Vector analyzing power for the proton-{sup 6}He elastic scattering at 71 MeV/nucleon has been measured for the first time, with a newly developed polarized proton solid target, which works at a low magnetic field of 0.09 T. The results are found to be incompatible with a t-matrix folding model prediction. Comparisons of the data with g-matrix folding analyses clearly show that the vector analyzing power is sensitive to the nuclear structure model used in the reaction analysis. The {alpha}-core distribution in {sup 6}He is suggested to be a possible key for understanding the nuclear structure sensitivity.

The status and prospects of 2-nucleon and 3-nucleon short range correlations (SRCs) studies at Nuclotron-M (JINR) are presented. This program is focused on the investigations of the spin part of SRCs with polarized deuteron beam from new high intensity polarized deuterons ion source which is under development at JINR. The wide experimental program on the systematic studies of the polarization effects in dp- elastic scattering, dp- nonmesonic breakup, dd → 3Hen(3Hp) and d3He → p4He reactions sensitive to SRCs using both internal and extracted beam at Nuclotron-M is presented.

Precision data are presented for the break-up reaction, $^2{\rm H}(\vec p,pp)n$, within the framework of nuclear-force studies. The experiment was carried out at KVI using a polarized-proton beam of 190 MeV impinging on a liquid-deuterium target and by exploiting the detector, BINA. Some of the vector-analyzing powers are presented and compared with state-of-the-art Faddeev calculations including three-nucleon forces effect. Significant discrepancies between the data and theoretical predictions were observed for kinematical configurations which correspond to the $^2{\rm H}(\vec p,^2$He$)n$ channel. These results are compared to the $^2{\rm H}(\vec p,d)p$ reaction to test the isospin sensitivity of the present three-nucleon force models. The current modeling of two and three-nucleon forces is not sufficient to describe consistently polarization data for both isospin states., 4 pages, 3 figures, submitted to PRL

A deuteron beam polarimeter has been constructed at the Internal Target Station at the Nuclotron of JINR. The polarimeter is based on spin-asymmetry measurements in the d-p elastic scattering at large angles and the deuteron kinetic energy of 270 MeV. It allows to measure vector and tensor components of the deuteron beam polarization simultaneously., Comment: 15 pages, 9 figures

The structure of N—d low‐energy scattering states is described using the hyperspherical harmonics method with realistic Hamiltonian models, consisting of two‐ and three‐nucleon interactions. Both coordinate and momentum space two‐nucleon potential models are considered. Results for the zero‐energy N—d scattering lengths and for the p—d phase shift and mixing angle parameters at center‐of‐mass energy of 2 MeV are presented and discussed.

Measurements of analyzing powers Ay, Ayy, and Axx for d‐p elastic scattering were performed at Ed = 0.88 and 2.0 GeV using a high‐energy deuteron beam polarimeter at the Internal Target Station of the Nuclotron at JINR. The analyzing power data at 0.88 GeV are compared with several theoretical calculations.