Transient effects in fission evidenced from new experimental signatures

A new experimental approach is introduced to investigate the relaxation of the nuclear deformation degrees of freedom. Highly excited fissioning systems with compact shapes and low angular momenta are produced in peripheral relativistic heavy-ion collisions. Both fission fragments are identified in atomic number. Fission cross sections and fission-fragment element distributions are determined as a function of the fissioning element. From the comparison of these new observables with a nuclear-reaction code a value for the transient time is deduced.Comment: 6 pages, 2 figures, background information at http://www-w2k.gsi.de/kschmidt

Radiobiological effects of highly charged ions Their relevance for tumor therapy and radioprotection in space

Generally, radiobiology is mostly concerned with the influence of sparsely ionising radiation like X- or gamma-rays and electrons. In the last 50 years, however, the radiobiological action of heavy charged particles like protons or heavier ions has been studied with increasing intensity. This is for two reasons: first, heavy charged particles represent the best tool for an external radiotherapy of inoperable tumors. This is due to the favourable depth dose distribution where the dose increases with penetration depth and because of the small lateral and longitudinal scattering that allows irradiation of deep-seated target volumes with optimum precision. In addition, for particles heavier than protons, i.e. in the region of carbon, the biological efficiency increases at the end of the beam's range while it is low in the entrance channel, thus allowing a better inactivation of otherwise very radioresistant cells of deep-seated tumors. The second important field for particle radiobiology is the application in radiation protection in space research. In space outside the magnetic shielding of the earth, high-energy protons from the sun and heavier particles up to iron from interstellar sources pose a genetic and carcinogenic risk for man and can also influence and destroy semiconductor devices like computers. Because of the very high energies of these particles, shielding becomes difficult and extremely expensive. (orig.)To be published in: The Physics of Highly and Multiply Charged Ions. Currell, F.J. (ed.), Kluwer Academic Publ. (2002)Available from TIB Hannover: RO 801(2002-20) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

What kind of radiobiology should be done at a hadron therapy center

Although therapy with heavy particles like neutrons, protons or heavier ions has now a rather long history of several decades, but there are more open questions than settled problems. This fact is really amazing because the use of the high LET particles, neutrons and heavy ions was strongly motivated by radiobiological arguments. Presently, the use of protons with a better physical dose distribution is more widely accepted than neutrons or heavy ions where the expected high LET benefit could not be verified clinically. This demonstrates that predictions made on the basis of radiobiological experiments cannot be transferred directly from in vitro experiments to the therapy situation. In particular, it is not possible to transfer an average RBE value measured in vitro in an extended exposure field to the treatment situation. Therefore, in the following section the dependence of RBE on LET, dose and radiosensitivity will be summarized and compared to models. Basic experiments illustrating the RBE problem in a particle field will be described. The fundamentals of a recently developed track structure model will be given and calculations will be compared to experiments. Finally, a short outline of possible future developments for radiobiology will be presented. (orig.)Available from FIZ Karlsruhe / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

The path of hot nuclei towards multifragmentation

The initial production and dynamical expansion of hot spherical nuclei are examined as the first stage in the projectile-multifragmentation process. The initial temperatures, which are necessary for entering the adiabatic spinodal region, as well as the minimum temperatures and densities, which are reached in the expansion, significantly differ for hard and soft equations of state. Additional initial compression, occurring in central collisions leads most likely to a qualitatively different multifragmentation mechanism. Recent experimental data are discussed in relation to the results of the proposed model. (orig.)25 refs.Available from TIB Hannover: RO 801(95-30) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Open-charm meson resonances with negative strangeness

We study heavy-light meson resonances with quantum numbers J"P = 0"+ and J"P = 1"+ in terms of the non-linear chiral SU(3) Lagrangian. Adjusting the free parameters that arise at subleading order to reproduce the mass of the D(2420) resonance as well as the new states established recently by the BABAR, CLEO and BELLE collaborations we obtain refined masses for the anti-triplet and sextet states. Bound states of antikaons at the D(1867) and D(2008) mesons are predicted at 2352 MeV (J"P = 0"+) and 2416 MeV (J"P = 1"+). In addition we anticipate a narrow scalar state of mass 2389 MeV with (I, S) = (1/2, 0). (orig.)Available from TIB Hannover: RO 801(03-29) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Laser for nuclear physics

An overview is given on the application of lasers in nuclear physics. The review focuses on atomic physics techniques for extracting nuclear properties such as the nuclear spin, the magnetic dipole moment, the spectroscopic quadrupole moment, and the changes of charge radii. References are given for the work performed in this field since 1988. At that time, E.W. Otten prepared an extensive review with a complete compilation of data on properties of nuclear ground and isomeric states, obtained by optical spectroscopy on unstable nuclei. (orig.)SIGLEAvailable from TIB Hannover: RO 801(03-02) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Anlage zum Bericht des Gutachterausschusses 'Komplexe Systeme der Kern- und Teilchenphysik' 1992 - 1994

Available from TIB Hannover / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEBundesministerium fuer Bildung, Wissenschaft, Forschung und Technologie, Bonn (Germany)DEGerman

GSI scientific report 1997

SIGLEAvailable from TIB Hannover: RA 3692(98-1) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

High energy density in matter produced by heavy ion beams. Annual report 1995

The main objective of experimental plasma physics activities is the interaction of heavy ion beams with dense ionized matter. The systematic investigations on beam stopping and beam plasma interaction were continued. Using cryogenic rare gas crystals the hydrodynamic motion of heavy ion beam heated solid matter could be observed at a specific deposition energy with Neon beams at 20 J/g. Along with these investigations technical improvements at the plasma lens for final focussing and new methods for plasma diagnostics have been developed, essential assets for future experiemtns at much higher beam intensities. With the intensity upgrade program at GSI now underway, a specific deposition power of up to about 10 TW/g will be expected after completion in 1998, opening exciting perspectives for research in this field. Accelerator research and development at GSI is concentrating on aspects of beam dynamics in storage rings and final transport, and at Frankfurt on RFQ development and low energy beam transport. The new experimental research activities on the dynamics of space charge dominated beams are in progress at the GSI accelerator facility. Experiments on the longitudinal instability at the ESR with cooled beams and at the SIS have shown good agreement with theoretical predicitions, increasing the confidence in extrapolations to a driver storage ring. In Frankfurt a number of high-current issues is under consideration, such as a high-current Bi"+ ion source, funneling of 2 beams, and charge neutralization. Studies on target theory are well in progress at MPQ and in Frankfurt in close international collaboration, in particular with other European groups. They are focussed on implosion physics of hohlraum targets. The need for an appropriate target for the ignition facility has stimulated a coherent effort for target studies using existing radiation hydrodynamics codes, as well as for the development of 2- and 3-dimensional integrated simulation codes for target design. Other relevant topics, such as fast ignition and ion stopping are under investigation. (orig.)SIGLEAvailable from TIB Hannover: RA 3692(96-02) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Slide-report of the joint DESY/GSI/NuPECC workshop ''Electron-nucleon/nucleus collisions

SIGLEAvailable from TIB Hannover: RA 3692(97-04) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman