Three-body break-up in deuteron-deuteron scattering at 65 MeV/nucleon

Abstract

Abstract. We successfully identified several multibody final states in deuteron-deuteron scattering at 65 MeV/nucleon at KVI using a unique and advanced detection system called BINA. This facility enabled us to perform cross sections and polarization measurements with an improved statistical and systematic precision. The analysis procedure and a part of the results of the three-body break-up channel in the deuteron-deuteron scattering at 65 MeV/nucleon are presented.The physics phenomena of nuclei are for a large part understood by considering the interaction between their building blocks, the nucleons. In 1935 Yukawa described the nucleon-nucleon (NN) force by the exchange of massive mesons [1] in analogy to the electromagnetic interaction which can be represented by the exchange of of a massless photon. Several phenomenological nucleonnucleon potentials have been derived based on Yukawa's theory and are able to reproduce the whole bulk of data points in neutron-proton and proton-proton scattering with extremely high precision. These so-called high-quality NN potentials are used in Faddeev equations [2,3] to give an exact solution of the scattering problem of the threenucleon system. Already, for the simplest three-nucleon system, the triton, an exact solution of the three-nucleon Faddeev equations employing two-nucleon forces (2NFs) underestimates the experimental binding energy [4], showing that 2NFs are not sufficient to describe the threenucleon system accurately. The existence of an additional force, the three-nucleon (3N) interaction, was predicted by Primakov [5] and confirmed by a comparison between precision data and state-of-the-art calculations. In general, adding 3NF effects to the NN potentials gives a better agreement between the cross section data of the protondeuteron scattering and corresponding calculations [6][7][8][9][10][11][12][13][14][15][16][17], whereas a similar comparison for the spin observables yields various discrepancies [7][8][9][18][19][20][21][22]. This demona e-mail: ramazani@kvi.nl strated that spin-dependent parts of the 3NFs are poorly understood and that more studies in this field are needed.The 3NF effects are in general small in the threenucleon system. A complementary approach is to examine heavier systems for which the 3NF effects are significantly enhanced in magnitude. For this, it was proposed to study the four-nucleon system since the experimental database in the four-nucleon system is presently poor in comparison with that of the three-nucleon system. Most of the available data have been measured at very low energies, in particular below the three-body break-up threshold of 2.2 MeV. Also, theoretical developments are evolving rapidly at low energies [23][24][25][26], but lag behind at higher energies. The experimental database at intermediate energies is very limited [27][28][29]. This situation calls for extensive four-nucleon studies at intermediate energies. The goal of our work was to perform a comprehensive measurement of the cross sections and spin observab...

Spin observables in the three-body break-up process near the quasi-free limit in deuteron–deuteron scattering

“…The polarization of the deuteron beam was measured as well in the low-energy beam line with a Lamb-Shift Polarimeter (LSP) [57]. The polarization values obtained with the LSP were found to be in an excellent agreement with the ones measured with BINA [52]. For a part of phase space in the dp elastic reaction in which both particles are scattered to the forward angles, data on T 20 were compared with the results of the threebody reaction in the deuteron-deuteron scattering.…”

“…Each configuration corresponds to a small region in the scattering angles of the deuteron and proton, their relative azimuthal angle, and their relative energy represented by the variable S as explained in detail in Ref. [52]. The five-fold differential cross section is at its maximum when the energy of the neutron is very small.…”

“…In the first experiment, a polarized beam of deuterons with a kinetic energy of 65 MeV/nucleon was impinged on a liquid deuterium target [56]. The elastic channel, the neutron transfer channel, and break-up channels leading to three-and four-body final states were uniquely identified using the information on the energies of the outgoing particles, their scattering angles, and their time-of-flight (TOF) [51,52]. We note that the three-body break-up channel in deuterondeuteron scattering is extremely rich in phase space even more than the p + d reaction since its final state is composed of nonidentical particles.…”

“…We made use of this reaction to check the systematic uncertainties and also to measure the polarization of the beam of deuterons [52]. The vector and tensor polarizations of the beam was determined by combining measurements of the azimuthal asymmetries of the reaction yield and the published data for iT 11 and T 22 .…”

“…The feasibility of identifying and measuring spin observables in the three-body break-up reaction in deuteron-deuteron scattering has been reported recently in Refs. [51,52].…”