Spin Polarization ofK37Produced in a Single-Proton Pickup Reaction at Intermediate Energies

Abstract

Spin polarization of 37K nuclei produced via single proton pickup from a 9Be target by a beam of 150 MeV/nucleon 36Ar has been observed. Positive spin polarization with magnitude (8.5+/-0.6)% was deduced near the peak of the 37K momentum distribution. The variation of the spin polarization as a function of outgoing 37K momentum is explained by a classical conservation model, as previously applied to describe the induced spin polarization observed for fragments produced in intermediate-energy heavy-ion reactions, with the condition that the picked-up proton has an average momentum equal to the Fermi momentum and is aligned along the incident beam direction.

Precise nuclear moments of extremely proton-rich nuclus 23 Al

“…However, the statistics was insufficient to discuss further details of the nuclear structure because of very small production rate of 23 Al nuclei. In the present work, by using the pick-upfragmentation process [3,4] to produce polarized 23 Al nuclei, we succeeded to gain the production rate by around ten times larger. Therefore, we have measured the electric quadrupole coupling constant eqQ/ h of 23 Al in an Al 2 O 3 single crystal using the β-ray detecting nuclear quadrupole resonance in the strong external field (β-NQR) for the first time.…”

“…The polarized 23 Al nuclei were produced through the pick-up and fragmentation process of the intermediate-energy nuclear collisions of 100-AMeV 24 Mg 12+ ions and 9 Be atoms in a 2.5-mm-thick production target [3,4]. The production cross section of the pick-up fragmentation is about ten times larger than that of the pure fragmentation process, 28 Si + 9 Be, which was utilized in the previous work [2].…”

Spin polarization ofAl34fragments produced by nucleon pickup at intermediate energies

“…The pickup kinematics are detailed by Groh et al [1]. The theoretical method presented here is based on this description and interpreted in the Asahi code.…”

“…Nevertheless, the fragmentation reaction mechanisms have the inconvenience to produce a spin-polarization close to zero for the maximum in the fragment yield distribution as a function of the selected fragment momentum. On this point, a new and very promising aspect of spin-polarization in heavy-ion reactions has been recently investigated [1]. A significant spin polarization has been observed in a single proton pickup reaction at the peak of the fragment momentum yield curve.…”

“…The mechanism would be fundamentally the same as in fragmentation, but as the picked-up nucleon on average has the Fermi momentum in the beam direction, positive spin-polarization is predicted at the peak of the momentum distribution. In this work, we present the further modifications of the kinematical model in the aim to take into account the characteristic features of pickup reactions, as proposed in the work of Groh et al [1], and we compare experimental results to these model predictions.…”