Exclusive breakup of Li7 incident on a proton target at 5.44A MeV

Abstract

An exclusive measurement of the breakup of 7 Li incident on a proton target was performed at 38.1 MeV (5.44 MeV/nucleon), probing the direct part of the excitation to the continuum. The two cluster constituents of 7 Li, 4 He, and 3 H, were recorded in coincidence in the MAGNEX spectrometer and a silicon detector respectively. Both detection systems were set at forward angles and the measurement of both kinematical solutions allowed the determination of a breakup angular distribution over a wide angular range in the center-of-mass frame. Comprehensive simulations provided the detection efficiency of the system and via the appropriate kinematics the transformation of the cross sections from the laboratory to the center-of-mass reference frame. The experimental results are analyzed and discussed together with previous elastic scattering data using the Continuum Discretized Coupled Channels (CDCC) framework and are found to be in satisfactory agreement. It was found that while the breakup cross section was dominated by the nonresonant component, the most important influence on the elastic scattering was due to coupling to the 7/2 − resonance of 7 Li.

Study of continuum excitation by light weakly bound projectiles on proton target

“…The same conclusion remains valid even at the lower energy of 16 MeV where although the resonant breakup is alsmost zero, its coupling influence on elastic channel is the strongest one. The analysis of the 7 Li+p reaction at 38 MeV [8] yielded the same results, where strong coupling to the 7/2 − resonance of 7 Li is inferred althought the resonance is barely excited. This systematic behavior for both 6,7 Li + p systems, suggests that the strength of the coupling to the continuum excitation is not always correlated with the magnitude of the breakup cross section.…”

“…The 6 Li and 7 Li beams were delivered by the TANDEM accelerator and impinged on a thin CH 2 target. For the elastic scattering measurement [4][5][6], the 6 Li ( 7 Li) ejectiles were detected by the MAGNEX spectrometer while, for the breakup measurement [6][7][8] the α-particles were measured in MAGNEX in coincidence with 2 H ( 3 H) measured in a silicon detector, appropriately masked by a tantalum foil to avoid elastic scattering deterioration. The angular range covered by MAGNEX was 0 o ≤θ lab ≤10 o , while for the silicon detector was 4 o ≤θ lab ≤6 o .…”

Breakup of Li6+p at near-barrier energies and the effect on elastic scattering

“…A similar situation was met with for the elastic scattering of 7 Li from a proton target recently reported in Ref. [35]. In that case, the cross section for excitation of the first (7/2 − ) α + t resonance was determined to be ∼0.5 mb compared a total breakup of 66 mb, while the coupling to resonant breakup was found to be dominant.…”

“…The exclusive yields were transferred to laboratory double differential cross sections (d 2 σ/d α d d ) using a detection efficiency estimated through a Monte Carlo three-body simulation code [34,35]. Our code takes into account the 6 Li + p reaction, leading to an excited state of 6 Li * with an angular distribution determined in the CDCC calculation to be described below.…”

Coherent coupled-reaction-channels analysis of existing and new p + Be9 data between 1.7 and 15 MeV/nucleon

“…Our ongoing systematic study of the interactions of protons with light weakly bound nuclei in inverse kinematics, completed for 6,7 Li with measurements of elastic scattering [1][2][3] and reactions [3][4][5][6][7], is here extended to the elastic scattering of the Borromean nucleus 9 Be. This nucleus still attracts considerable interest due to its role in astrophysical problems of building up the heavy elements and triggering the r process [8][9][10][11].…”