0000000000406732
AUTHOR
U. Lynen
Onset of nuclear vaporization inAu197+197Au collisions
Multifragmentation has been measured for [sup 197]Au+[sup 197]Au collisions at [ital E]/[ital A]=100, 250, and 400 MeV. The mean fragment multiplicity increases monotonically with the charged particle multiplicity at [ital E]/[ital A]=100 MeV, but decreases for central collisions with incident energy, consistent with the onset of nuclear vaporization. Molecular dynamics calculations follow some trends but underpredict the observed fragment multiplicities. Including the statistical decay of excited residues improves the agreement for peripheral collisions but worsens it for central collisions.
Fragment Flow and the Multifragmentation Phase Space
Fragment distributions have been measured for Au+Au collisions at [ital E]/[ital A]=100 and 1000 MeV. A high detection efficiency for fragments was obtained by combining the ALADIN spectrometer and the MSU-Miniball/WU-Miniwall array. At both energies the maximum multiplicity of intermediate mass fragments (IMF) normalized to the size of the decaying system is about one IMF per 30 nucleons but the element distributions show significant differences. Within a coalescence picture the suppression of heavy fragments in central collisions at [ital E]/[ital A]=100 MeV may be related to a reduction of the density in momentum space which is caused by the collective expansion.
Feasibility study for the measurement of πN transition distribution amplitudes at P¯ANDA in p¯p→J/ψπ0
The exclusive charmonium production process in (P) over barp annihilation with an associated pi 0 meson (p) over barp -> J/psi pi(0) is studied in the framework of QCD collinear factorization. The feasibility of measuring this reaction through the J/psi -> e(+) e(-) decay channel with the AntiProton ANnihilation at DArmstadt ((P) over bar ANDA) experiment is investigated. Simulations on signal reconstruction efficiency as well as the background rejection from various sources including the (P) over barp -> pi(+)pi(-)pi(0) and (p) over barp -> J/psi pi(0)pi(0) reactions are performed with PANDAROOT, the simulation and analysis software framework of the (P) over bar ANDA experiment. It is show…
Study of doubly strange systems using stored antiprotons
Bound nuclear systems with two units of strangeness are still poorly known despite their importance for many strong interaction phenomena. Stored antiprotons beams in the GeV range represent an unparalleled factory for various hyperon-antihyperon pairs. Their outstanding large production probability in antiproton collisions will open the floodgates for a series of new studies of systems which contain two or even more units of strangeness at the PANDA experiment at FAIR. For the first time, high resolution gamma-spectroscopy of doubly strange Lambda Lambda-hypernuclei will be performed, thus complementing measurements of ground state decays of Lambda Lambda-hypernuclei at J-PARC or possible …
Present status of the caloric curve of nuclei
Abstract Spectator decay was studied for the system Au + Au at an energy of 1000 A·MeV and the decay of the interaction region at energies between 50 and 200 A·MeV. In both cases temperatures were derived from several double-ratios of neighboring isotopes and from the population of excited states in 5 Li and 4 He. Agreement was found among the different isotope temperatures and also among the two excited state temperatures. The comparison of isotope and excited state temperatures, however, reveals large differences, which cannot be explained by feeding corrections. At incident energies between 600 and 1000 A·MeV the energy spectra of fragments and also neutrons of the decaying projectile sp…
Physics with Antiprotons at the Future GSI Facility
Recently GSI presented the plans for a major new international research facility (http://www.gsi.de/GSI-future/). Highly luminous secondary beams with excellent quality encompassing the production of antiprotons will be delivered. In a High Energy Storage Ring (HESR) with a bending power of 50 Tm antiprotons will be cooled either stochastically or by electrons. The envisaged limits are a momentum range of 1.5 to 15 GeV/c and a luminosity of 2 × 1032 cm-2 s-1. Four major physical research goals can be addressed: high precision charmonium spectroscopy, medium effects of open and hidden charm, the search for glueballs and hybrids, and the production of hypernuclei.
Electromagnetic fission of $^{238}$U at 600 and 1000 MeV per nucleon
Electromagnetic fission of238U projectiles at E/A =600 and 1000 MeV was studied with the ALADIN spectrometer at the heavy-ion synchrotron SIS. Seven different targets (Be, C, Al, Cu, In, Au and U) were used. By considering only those fission events where the two charges added up to 92, most of the nuclear interactions were excluded. The nuclear contributions to the measured fission cross sections were determined by extrapolating from beryllium to the heavier targets with the concept of factorization. The obtained cross sections for electromagnetic fission are well reproduced by extended Weizsacker-Williams calculations which include E1 and E2 excitations. The asymmetry of the fission fragme…
"Table 1" of "Electromagnetic fission of U-238 at 600-MeV and 1000-MeV per nucleon"
Electromagnetic fission.