Precision data are presented for the break-up reaction, H2(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 H2(p→,He2)n channel. These results are compared to the H2(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.
A selection of measured cross sections and vector analyzing powers,
A
x
and
A
y
, are presented for the
p
→
d
break-up reaction. The data are taken with a polarized proton beam with a kinetic energy ...of 135 MeV using the Big Instrument for Nuclear-polarization Analysis (BINA) at KVI, the Netherlands. With this setup,
A
x
is extracted for the first time for a large range of energies as well as polar and azimuthal angles of the two outgoing protons. For most of the configurations, the results at small and large relative azimuthal angles differ in behavior when comparing experimental data with the theoretical calculations. We also performed a more global comparison of our data with theoretical calculations. The cross-section results show huge values of
χ
2
/d.o.f.. The absolute values of
χ
2
/d.o.f. for the components of vector analyzing powers,
A
x
and
A
y
, are smaller than the ones for the cross section, partly due to larger uncertainties for these observables. However, also for these observables no satisfactory agreement is found for all angular combinations. This implies that the present models of a three-nucleon force are not able to provide a satisfactory description of experimental data.
Vector-analyzing powers,
A
x
and
A
y
, of the proton–deuteron break-up reaction have been measured by using a polarized-proton beam at 135 MeV impinging on a liquid-deuterium target. For the ...experiment, the big instrument for nuclear-polarization analysis (BINA) was used at KVI, Groningen, the Netherlands. The data are compared to the predictions of Faddeev calculations using state-of-the-art two- and three-nucleon potentials. Our data are reasonably well described by calculations for the kinematical configurations at which the three-nucleon force (3NF) effect is predicted to be small. However, striking discrepancies are observed at specific configurations, in particular in the cases of symmetric configurations, where the relative azimuthal angle between the two protons is small which corresponds to the
d
(
p
→
,
2
He
)
n
channel. The vector-analyzing powers of these configurations are compared to the proton–deuteron elastic scattering to study the spin–isospin sensitivity of the 3NF models. The results are compared to the earlier results of the proton–deuteron break-up reaction at 190 MeV proton-beam energy
1
. Disagreement is observed for both proton-beam energies between data and calculations which points to a deficiency in the treatment of spin–isospin part of the 3NF.
A measurement of the analyzing powers for the
2
H
(
p
→
,
p
p
)
n
break-up reaction was carried out at KVI exploiting a polarized-proton beam at an energy of
135
MeV
. The scattering angles and ...energies of the final-state protons were measured using the Big Instrument for Nuclear-polarization Analysis (BINA) with a nearly
4
π
geometrical acceptance. In this work, we analyzed a large number of kinematical geometries including forward–forward configurations in which both the final-state particles scatter to small polar angles and backward–forward configurations in which one of the final-state particles scatters to large polar angles. The results are compared with Faddeev calculations based on modern nucleon–nucleon (NN) and three-nucleon (3N) potentials. Discrepancies between polarization data and theoretical predictions are observed for configurations corresponding to small relative azimuthal angles between the two final-state protons. These configurations show a large sensitivity to 3N force effects.
Understanding of the exact nature of three-nucleon forces is the most challenging topic in the field of nuclear physics. Three-nucleon break-up reaction is a good tool to look into the underlying ...dynamics of the nuclear force, thanks to its rich kinematical phase space which has different levels of sensitivity to three-nucleon force effects. The recent studies on few-nucleon systems have revealed that the current nuclear force models cannot describe nucleon-deuteron scattering data accurately. In the present work, the analyzing powers of the proton-deuteron break-up reaction obtained using a 190 MeV polarized proton beam will be discussed. We present for the first time the vector analyzing powers for the kinematics in which one of the protons scatters to intermediate and large scattering angles at this energy. The results show a fairly good agreement with various theoretical predictions for both intermediate and large scattering angles of the break-up phase space.
Detailed measurements of five-fold differential cross sections and a rich set of vector and tensor analyzing powers of the
2
H
(
d
,
d
p
)
n
break-up process using polarized deuteron-beam energy of ...65 MeV/nucleon with a liquid-deuterium target are presented. The experiment was conducted at the AGOR facility at KVI using the BINA 4
π
-detection system. We discuss the analysis procedure including a thorough study of the systematic uncertainties. The results can be used to examine upcoming state-of-the-art calculations in the four-nucleon scattering domain, and will, thereby, provide further insights into the dynamics of three- and four-nucleon forces in few-nucleon systems. The results of coplanar configurations are compared with the results of recent theoretical calculations based on the Single-Scattering Approximation (SSA). Through these comparisons, the validity of SSA approximation is investigated in the Quasi-Free (QF) region.
We present measurements of differential cross sections and analyzing powers for the elastic
2
H
(
d
,
d
)
d
scattering process. The data were obtained using a 130 MeV polarized deuteron beam. Cross ...sections and spin observables of the elastic scattering process were measured at the AGOR facility at KVI using two independent setups, namely BINA and BBS. The data harvest at setups are in excellent agreement with each other and allowed us to carry out a thorough systematic analysis to provide the most accurate data in elastic deuteron-deuteron scattering at intermediate energies. The results can be used to confront upcoming state-of-the-art calculations in the four-nucleon scattering domain, and will, thereby, provide further insights in the dynamics of three- and four-nucleon forces in few-nucleon systems.
The role of pions in the nuclear interaction has been studied in pionic fusion experiments using the AGOR accelerator facility at KVI. Pionic fusion is a highly coherent process in which two nuclei ...fuse to a united nucleus and the available centre-of-mass (C.M.) energy is emitted through the pion channel. The examined reactions were 4He(3He, π0)7Be and 6Li(4He, π0)10B⁎ and both reactions were performed at C.M. energies about 10 MeV above the coherent pion production threshold. Here, the experimental results for the 6Li(4He, π0)10B⁎ reaction will be presented and discussed. In order to provide sensitivity to the full dynamics and relevant processes involved in the pionic fusion reaction, almost the full angular distribution of neutral pions has been determined. In a phenomenological analysis, the contributions of Legendre polynomials to reproduce the behaviour of the angular distribution have been studied. The results of this analysis confirm the importance of the clustering correlations for the 6Li(4He, π0)10B⁎ reaction. The mass dependence of the pionic fusion reaction is in agreement with the results of the existing models extrapolated to this reaction.
Crystallization of nanosize Fe36Cr12Mo10 phase during annealing process of amorphous Fe55−xCr18Mo7B16C4Nbx (X=0, 3, 4) alloys and also growth mechanisms were studied by X-ray diffraction and ...differential scanning calorimetric tests as well as TEM observations. Results of TEM observations showed that Fe36Cr12Mo10 phase crystallized in the structures of the alloys in separated perlitic colonies. Furthermore, it is proposed that Fe36Cr12Mo10 phase crystallized in the alloys in mottled morphology and about average size of 10nm. In addition, kinetic investigations revealed that not only nucleation frequencies but also growth rates were reduced simultaneously by Nb alloying in the alloys.
► We show the effects of Nb alloying on crystallization process in new kinds of Fe-based amorphous alloys. ► For the first time, we discern the unique morphology of Fe36Cr12Mo10 phase in Fe55−xCr18Mo7B16C4Nbx (X=0, 3, 4) alloys. ► We show the effects of Nb addition on decreasing nucleation frequency and growth rate in the alloys. ► Increasing both nucleation and growth activation energies by Nb alloying ► Increasing of the crystallization temperatures and activation energies after Nb addition
A radiative deuteron–proton capture experiment was carried out at KVI using polarized-deuteron beams at incident energies of 55, 66.5, and 90 MeV/nucleon. Vector and tensor-analyzing powers were ...obtained for a large angular range. The results are interpreted with the help of Faddeev calculations, which are based on modern two- and three-nucleon potentials. Our data are described well by the calculations, and disagree significantly with the observed tensor anomaly at RCNP.
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