Observation of fusion-like residues in energetic nuclear collisions at the Celsius storage ring

Recent experiments at the CELSIUS storage ring of Uppsala, Sweden, have revealed the existence of high momentum transfer target-like fragments contrary to expectations. Recoiling heavy fragments in the reaction of 250 MeV/nucleon 14 N on 131 Xe have been measured at lO with respect to the beam direction with specially designed recoil telescopes. Simulations with the Boltzmann-Uehling-Uhlenbeck (BUU) transport equation are not able to reproduce the experimental observations. Intermediate mass fragments (IMF: 3 ≤ Z ≤ 8) were also measured using three elements of the CHICSi Δ E-E telescopes. Single energy spectra of IMFs suggest that the larger fragments (Z = 7, 8) are preferentially emitted from a single equilibrated, but very hot source (T ∼ 9 MeV). (Author)