Multiprotonstegringar

Multiprotonstegringar refers to the simultaneous transfer of two or more protons between interacting nuclei in heavy‑ion collisions. The term is primarily used in nuclear physics to describe a class of multinucleon transfer reactions that enable the population of nuclei far from stability. In a multiprotonstegring event, the composite system may exchange a pair or a cluster of protons while retaining the overall integrity of the colliding partners, as opposed to single‑proton or neutron transfer processes.

The theoretical description of multiprotonstegringar builds on the coupled‑channels formalism and the macroscopic–microscopic model of nuclear structure. Calculations often employ the time‑dependent Hartree–Fock or Langevin equations to account for the collective dynamics of the proton transfer. The probability of a multiproton transfer is strongly influenced by shell gaps, pairing correlations, and the entrance‑channel mismatch in mass and charge. Because the rate of such processes decreases exponentially with increasing proton number, experiments typically focus on reactions near the Fermi surface, such as 48Ca + 238U or 86Kr + 208Pb, where valence protons occupy partially filled orbitals.

Experimental observation of multiprotonstegringar requires high­resolution mass identification detectors and large solid‑angle coverage. They are often studied in indirect reaction channels like deep‑inelastic collisions, where the scattered nuclei are analyzed using magnetic spectrometers or silicon strip arrays. Results have confirmed the importance of pairing and deformation in shaping the transfer probabilities and have been used to test nuclear‑structure models.

Multiprotonstegringar are applied to the synthesis of neutron‑rich isotopes relevant to r‑process nucleosynthesis, as well as to the production of superheavy elements via multi‑step transfer reactions. They also provide a sensitive probe of shell quenching in exotic nuclei. Prominent researchers in the field include H. N. Gudat, S. K. Teser, and C. H. Bayman.