Search

The results from studies of the differential cross section of elastic deuteron–proton scattering at 500–1000 MeV/nucleon on the Nuclotron Internal Targets Station are presented and compared to the available experimental data for similar energies, and to the results of theoretical calculations in the theory of relativistic multiple scattering.

The aim of the deuteron spin structure (DSS) experiment is to obtain polarization observables in dp elastic scattering and in dp breakup at large CMS angles (> 60°). The dp breakup reaction has been investigated by the scintillation detectors placed at the vicinity of the Internal Target Station (ITS) of Nuclotron. Calibration data have been obtained at the deuteron energy of 300 - 500 MeV. The main goal of this report is to present the calibration procedure of the ΔE - E detectors. Calibration coefficients are used to recover the deposited particle energy.

Analyzing power in elastic proton-proton scattering was obtained at the Nuclotron Internal Target Station using a polarized deuteron beam and a polyethylene target. The selection of useful events was performed using the time and amplitude information from scintillation counters. The asymmetry on hydrogen was obtained by the subtraction of the carbon background. The obtained analyzing power values are compared with the predictions of the partial-wave analysis SAID at the beam energies of 500 and 650 MeV/nucleon.

The the polarimeter upgrade program at the Nuclotron internal target is presented. This polarimeter is intended for polarization experiments to study of the spin structure of two- and three-nucleon systems. The simulation of the pd-elastic and pp-elastic scattering for 500 - 1000 MeV proton energy to optimize the experimental setup and the first test of new detectors are performed.

The results of measurements of the differential cross section for elastic deuteron–proton scattering at the energy of 700 MeV per nucleon that were performed at the internal target station of the nuclotron at the Joint Institute for Nuclear Research (JINR, Dubna) are presented. These data were obtained at angles in the range between 70◦ and 120◦ in the c.m. frame. The angular dependence obtained in this way is compared with world-averaged data at similar energies and with the results of theoretical calculations performed within the relativistic theory of multiple scattering.

Deuteron spin structure program is aimed on extraction of two and three nucleon forces information, including their spin dependent parts, from dp elastic and dp breakup processes investigated at intermediate energies. The dp elastic data were obtained at Internal Target Station of Nuclotron (JINR) in the energy range 400-1800 MeV using polarized deuteron beam. Strong sensitivity to the short range spin structure of the isoscalar nucleon-nucleon correlations is observed in deuteron analyzing powers. Preliminary results of the the cross section for the dp breakup reaction have been obtained at 400 MeV of deuteron energy.

Polarized and unpolarized data for the dp breakup reaction at deuteron energies of 270, 400 MeV and 300–500 MeV using \(\varDelta E - E\) technique are obtained. Dp elastic scattering has been investigated using polarized deuteron beam under various kinematic configurations in the angular range (\(65^{\circ }\)–\(135^{\circ }\)) in c.m. at deuteron energies of 400, 700, 800, 1000, 1100, 1300, 1500 and 1800 MeV. Preliminary results of analyzing powers obtained in dp elastic scattering at 800 MeV of deuteron energy are compared with the calculations based on relativistic multiple scattering model.

The results on the angular dependencies of the vectorAyand tensorAyyandAxxanalyzing powers in deuteron-proton elastic scattering at large scattering angles are presented. These data were obtained at internal target at the JINR Nuclotron in the energy range 400-1800 MeV using polarized deuteron beam from new polarized ion source. New data on the deuteron analyzing powers in the wide energy range demonstrate strong sensitivity to the short-range spin structure of the isoscalar nucleon-nucleon correlations observed earlier. The perspectives of further studies of the short-range correlations using carbon, polarized deuteron and proton beams are discussed.

The results of the Polarimeter upgrade at the Nuclotron internal target are presented. This Polarimeter is intended for experiments to study of the spin structure of two-nucleon and three- nucleon short-range correlations. The measurements are performed in the frame of the DSS project. The simulation of the pd-elastic and pp-elastic scattering for 500 - 1000 MeV proton energy to optimization of the experimental setup is performed.

The dp breakup reaction has been investigated by the scintillation detectors placed at the vicinity of Internal Target Station (ITS) of Nuclotron. Data have been obtained at the angles of 19° - 54° in the laboratory frame at the deuteron energy of 300 - 500 MeV in a various detector configurations in which the sensitivity to the three nucleon correlations and relativistic effects are assumed. Preliminary results of the five fold differential cross section for particular detector configurations of the dp breakup reaction at 400 MeV of deuteron energy have been obtained.

Experimental results concerning the kaon yield in the reaction d + Be → K±(0°) + X for values of the cumulative variable xc in the range between 0.88 and 1.37 are presented. Values in the region of xc ≥ 1 correspond to short nucleon-nucleon distances (deuteron-core region) at which nucleon wave functions begin overlapping each other, forming a cluster (flucton) where the hadron-matter density is higher than the average matter density in the nucleus. The behavior of the K+/K− yield ratio in this region may be interpreted within the hypothesis that the quark sea in nuclei becomes harder because of the presence of a flucton component in nuclear matter.

The main goal of the deuteron spin structure project is to investigate the spin structure of nucleon–nucleon and three nucleon short-range correlations via the measurements of the polarization observables in the deuteron induced reactions at intermediate energies at Nuclotron (Dubna, Russia). In this framework, dp nonmesonic breakup and dp elastic reactions are investigated using internal target station. The dp breakup data are obtained with the detection of two outgoing protons at the angles of $$19^{\circ }$$ – $$54^{\circ }$$ in lab. frame at the deuteron energies of 300–500 MeV. The data of dp elastic scattering for the deuteron energies up to 2000 MeV are obtained in angular range $$70^{\circ }$$ – $$120^{\circ }$$ in cm. The further perspectives of the investigations using polarized deuteron beam as well as the studies of the $${}^3{\mathrm{He}}(d,p){}^4{\mathrm{He}}$$ reaction are discussed.

A complex of detection equipment based on scintillation detectors for investigating dp elastic scattering at the internal target of the Nuclotron developed in the framework of the Deuteron Spin Structure (DSS) project is presented. The results of optimizing scintillation detectors and the results of test measurements of a deuteron beam of the Nuclotron are given.

Experimental results on the vector (A y ) and tensor (A yy ) analyzing powers in the fragmentation of 5- and 9-GeV/c polarized deuterons to high-momentum pions in the kinematical region corresponding to pion production on a strongly correlated nucleon pair (cumulative meson production) are presented. The angular and momentum dependences of A yy are not described by calculations performed in the impulse approximation by using standard deuteron wave functions. An explanation for our data should be sought on the basis of models that treat the deuteron at short distances (deuteron-core region) as a multiquark state—for example, a 6q cluster, whose high orbital angular momentum (D wave) leads to the observed strong dependence of the reaction tensor analyzing power A( $\vec d$ , π)X on the pion transverse momentum.

A design for a ΔE-E detector to investigate deuteron breakup in the Nuclotron-M internal target in a deuteron energy interval of 300–500 MeV is presented. The high-voltage power supply system of the PMT-63, which is based on the computer-controlled Wenzel Electronik module, is briefly described. A light-emitting diode (LED) monitoring system for the ΔE-E detector is considered. The results of testing the ΔE-E detector using cosmic muons and deuteron beams of the Nuclotron are presented.

The results of measurements and the handling procedure of data on the tensor polarization of the deuteron beam arising as the beam passes through matter obtained at the Nuclotron during the June 2008 run using an extracted unpolarized 5 GeV/c deuteron beam are described. The effect observed is compared with calculations made in the framework of the Glauber multiple-scattering theory.

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 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 tensor polarization of the deuteron beam arising as deuterons pass through a carbon target was measured. The experiment was performed with an extracted unpolarized 5-GeV/c deuteron beam of the Nuclotron. The effect observed is compared with the calculations made using the Glauber multiple scattering theory.

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.

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.

First results of a soft photon yield in nucleus-nuclear interactions at 3.5 GeV per nucleon are presented. These photons have been registered at Nuclotron (LHEP, JINR) by an electromagnetic calorimeter built in the SVD Collaboration. The obtained spectra confirm the excess yield in the energy region less than 50 MeV in comparison with theoretical predictions and agree with previous experiments at high-energy interactions., 5 pages, 3 figures, presented at the International Conference on New Photo-detectors July 6-9, 2015, Moscow, Troitsk, Russia

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.

The tensor analyzing power A y y in inclusive breakup of 9.0 GeV/c deuterons on hydrogen and carbon has been measured at different emission angles of protons. The data are compared to calculations within the framework of light-front dynamics by using different deuteron wave functions. The results suggest that the relativistic deuteron structure may depend on more than one independent variable.

A study of spin effects at fragmentation of 9 GeV polarized deuterons into high momentum pions d A → π (θ) X was for the first time performed at Dubna polarized deuteron facility. Large D -state effects were observed at fragmentation of tensor polarized deuterons into cumulative pions at non-zero emission angles.

The invariant differential cross section, the tensor analyzing power A yy , and the vector analyzing power A y for the reaction 9Be(d, p)X are measured at an initial deuteron momentum of 4.5 GeV/c and a proton detection angle of about 80 mrad. The data obtained for the differential cross section are consistent with the results of measurements at 3.5 and 5.78 GeV/c and a proton emission angle of 2.5°. The values found for the tensor analyzing power A yy are compared with similar data obtained previously for the deuteron-fragmentation process occurring on a carbon target at various values of the initial deuteron momentum and leading to proton emission at zero angle. The data on the differential cross section for the reaction 9Be(d, p)X can be satisfactorily described within the relativistic impulse approximation by using standard deuteron wave functions; however, the approach based on this conceptual framework proves to be inadequate in dealing with data on the tensor analyzing power. These results indicate that it is necessary either to change the method for describing the relativistic deuteron or to take into account additional mechanisms.

The tensor-analyzing power A yy in inclusive breakup of 4.5 GeV/c deuterons on beryllium has been measured at ∼ 80 mr of the detected proton angle. The analyzing power remains positive up to the highest measured momentum of the proton, that is in definitive contradiction with the predictions of the existing models based on the standard deuteron wave functions. The results suggest that the deuteron structure at short distances may depend on more than one independent variable.

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.

The experimental program on the study of deuteron-proton interaction at Internal Target at Nuclotron is discussed. Recent results on the deuteron vector and tensor analyzing powers in dp -elastic scattering obtained at intermediate energies are presented. The status of the DSS setup upgrade is reported.

The behavior of the inclusive cross sections for the cumulative production of π± mesons and protons in pA, DA, and 4HeA interactions is studied versus the atomic mass number of fragmenting nuclei. The primary-beam momenta were 4.5 GeV/c per nucleon. Secondary pions and protons were recorded with a fixed momentum of 0.5 GeV/c at an angle of 120°. Specifically, the experiment explored the fragmentation of D, He, 6Li, 7Li, C, Si, 58Ni, 64Ni, 64Zn, 114Sn, 124Sn, and Pb nuclei. The energy spectra of π+ and π− mesons and protons with momenta in the range 0.3–0.7 GeV/c (the emission angle being 120°) were measured in an 8.9-GeV/c proton beam for Ni, Zn, and Sn isotopes. The special features in the behavior of the cross sections are found and discussed, and a comparison is drawn with the results of other studies.

The tensor analyzing power T20 of the reaction d +A→π − (0°)+X has been measured in the fragmentation of 9 GeV tensor polarized deuterons into pions with momenta from 3.5 to 5.3 GeV/c on hydrogen, beryllium and carbon targets. This kinematic range corresponds to the region of cumulative hadron production with the cumulative variable xc from 1.08 to 1.76. The values of T20 have been found to be small and consistent with positive values. This contradicts the predictions based on a direct mechanism assuming NN collision between a high momentum nucleon in the deuteron and a target nucleon (NN→NNπ).

The tensor analyzing power A yy in inclusive breakup of 9 GeV/c deuterons on carbon has been measured at the detected proton angle of 85 mr. The analyzing power remains positive at the highest measured momentum of the proton in definite contradiction with the predictions of the existing models. The vector analyzing power A y has been obtained simultaneously with A yy .

The tensor analyzing power T 20 for the reaction d ↑ + 12 C → π ± (0°) + X has been measured with a polarized deuteron beam from 6.2 to 9.0 GeV/ c at a pion momentum3.0 GeV/ c . This experiment is focused on “cumulatively produced pions”, which are produced beyond the kinematically allowed limit for free nucleon-nucleon collisions. The measured values of T 20 turn out to be close to zero. They are in disagreement with the results of our impulse approximation calculation which is based on a single NN → πNN interaction and takes into account the internal motion of nucleons in the deuteron. Possible explanations of the result are discussed.

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.

Deuteron induced reactions at intermediate energies are investigated at Internal Target Station (ITS) of Nuclotron. The dp elastic scattering data have been accumulated in the angular range (70° - 120°) in c.m from 0.3 to 2.0 GeV of deuteron energy. Part of the obtained results of differential cross sections and analyzing powers of dp elastic scattering are compared with theoretical predictions based on relativistic multi-scattering model. The dp breakup data are obtained with the detection of two outgoing protons at the angles of (19° - 54°) in laboratory frame at the deuteron energies from 0.3 to 0.5 GeV in various detector configurations. One of the tools to study spin structure of short range correlations is the measurements of the cross section, tensor analyzing power T 20 and spin correlation parameter Cy,y in the d 3 He → p (0°)4 He reaction at the energies between 1.0 and 1.75 GeV using polarized 3 He target and extracted polarized deuteron beam from new polarized ion source at Nuclotron. For this purposes the feasibility study has been performed. Proposed experiments on extracted deuteron beam of Nuclotron is aimed to investigate: non-nucleonic degrees of freedom and baryonic resonances properties in the d(A,d(0°))X and d(A,π -(0°))X reactions at different energies, non-nucleonic degrees of freedom via the measurements of the tensor Ayy and vector Ay analyzing powers in d(A,π -)X reaction and polarization properties of the baryonic resonances in the d(A,d)X reaction and others. First measurement of vector and tensor polarization of new polarized ion source has been performed in June-July of 2016y.

The results of experiments on photon and π 0 pairs production in interactions of 5.5 GeV/c protons, 2.75 and 3.83 GeV/c per nucleon deuterons with carbon and copper nuclei are presented. As previously reported (see. [1] and references therein), along with π 0 and η mesons, a resonance structure in the invariant mass spectrum of two photons at Mγγ = 360 ± 7 ± 9 MeV is observed in the reaction dC → γ + γ + X at momentum 2.75 GeV/c per nucleon. Here are some results of testing the signal and results of statistical analysis of the experimental data which allow to explain the lack of appearance of the signal in other experiments [2, 3] and make predictions for possible appearances of the signal in upcoming experiments.

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

Data on the tensor and vector analyzing powers (A yy and A y , respectively) in the fragmentation of a 9-GeV/c deuteron on hydrogen and carbon nuclei at high proton transverse momenta are presented. These data are compared with the results of relevant calculations performed within light-front dynamics by using various deuteron wave functions. The best description of the data is attained with the relativistic deuteron wave function derived within field-theory light-front dynamics.

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

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.

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.

A high‐energy deuteron beam polarimeter based on the d‐p elastic scattering at backward angles has been constructed at Internal Target Station of Nuclotron at JINR. Calibration measurement of the analyzing powers Ay, Ayy, and Axx with polarized deuteron beams at 0.88 and 2.0 GeV was performed.

The Ayy data for deuteron inclusive breakup off hydrogen and carbon at a deuteron momentum of 9.0 GeV/c and large Pt of emitted protons are presented. The large values of Ayy independent of the target mass reflect the sensitivity of the data to the deuteron spin structure. The data obtained at fixed $x$ and plotted versus Pt clearly demonstrate the dependence of the deuteron spin structure at short internucleonic distances on two variables. The data are compared with the calculations using Paris, CD-Bonn and Karmanov's deuteron wave functions., Comment: 4 pages, 2 figures, talk given at the SPIN2004 Conf., 10-16 Oct. 2004, Triest, Italy

Tensor analyzing power T20 of the reaction dA→π(0°)X was measured in the fragmentation of 9 GeV deuterons into points with the momenta from 3.5 to 5.3 GeV/c at hydrogen, beryllium and carbon targets. This momentum range corresponds to region of cumulative pion production The values of T20 are found to be small and consistent with positive values in contradiction with the Impulse Approximation calculations based on assuming a direct mechanism of pion production (NN→NNπ). New data on tensor Ayy analyzing power for pion production at the non-zero angle (θπ=135,180mr) with pion transverse momenta up to Pt=0.8 GeV/c are presented. Ayy increases with rise of Pt in the cumulative region.

Vector Ay and tensor Ayy analyzing powers of the inelastic scattering of deuterons with the momenta of 4.5 GeV/c on 9Be and 9 GeV/c on 1H and 12C at an angle of ∼80 mr in the vicinity of the excitation of baryonic resonances with masses between 1200 and 2200 MeV/c2 have been measured. The values of parameter Ay suggest that the role of the spin‐dependent part of the NN → NN* elementary processes is significant. The new Ayy data are in good agreement with the previous data at 4.5, 5.5 and 9 GeV/c, obtained at a zero angle, in an overlapping region of t. The results of the experiments are compared with the calculations within the PWIA and ω‐meson exchange model. The data obtained show that polarization observables of (d,d′) reaction in the vicinity of the excitation of baryonic resonances may be used to study their properties.

The data on the tensor analyzing power Ayy in the deuteron breakup reaction on hydrogen and nuclei (9Be and 12C) obtained at 9 and 4.5 GeV/c up to proton transverse momenta of ∼900 MeV/c are presented. The data demonstrate an approximate independence on the A-value of the target, as well as on the deuteron initial momentum, when they are plotted versus variables α and pT, that describe the internal motion of nucleons in the deuteron. The results suggest that a deuteron structure function at short distances may depend on more than one independent variable unlike an ordinary wave function.

Tensor analyzing power T20 in dA→π(θ=0°)X has been measured at fragmentation of 9 GeV deuterons into pions with the momenta from 3.5 to 5.3 GeV/c at H-, Be-, and C-targets. This momentum range corresponds to region of cumulative pion production where the deuteron core structure up to r≃0.4 fm is probed. The values of T20 are found to be small and positive in contradiction with the Impulse Approximation calculations assuming a direct mechanism of pion production on high momentum nucleon in the deuteron (NN→NNπ). In this report we present new data on tensor Ayy analyzing powers at non-zero angles (θ=135,180mr) with pion transverse momenta up to Pt=0.8 GeV/c. Ayy increases with rise of Pt in the cumulative region reaching the magnitude of −0.4 at Pt=0.7–0.8 GeV/c.

Preliminary data on the tensor analyzing power A yy in breakup of 9 GeV/c deuterons on hydrogen and carbon nuclei at secondary proton transverse momenta up to ~ 900 MeV/c are presented. The results suggest that a deuteron structure function at short distances can depend on more than one independent variable unlike an ordinary wave function.

The tensor analyzing power A yy in inclusive breakup of 9 GeV/c deuterons on carbon has been measured at 85 mrad of the detected proton angle using polarized beam of the Synchrophasotron of the Laboratory for High Energies of JINR. The analyzing power A yy remains positive at the highest measured momentum of the proton in definite contradiction with the predictions based on the standard nucleon-nucleon potentials.

Tensor analyzing power T 20 of the reaction d ↑ A → π–(0°)X was measured in the fragmentation of 9 GeV deuterons into pions with momenta from 3.5 to 5.3 GeV/c on hydrogen, beryllium and carbon targets. This momentum range corresponds to the region of cumulative production with the cumulative variable x c from 1.08 to 1.76. The values of T 20 were found to be small and consistent with positive values in contradiction with the predictions based on a direct mechanism assuming N N collision between a high momentum nucleon in the deuteron and a target nucleon (N N → N N π).