• Direct Observation of Bound Beta Decay at the FRS/ESR
  
  
• The Heavy Even-Even-Nucleus 270-110 and its Decay Products
  
  
• Coulomb Break-Up of Boron-8 and the Solar Neutrino Flux
  
  
• Hades Prepares for First Physics Experiments
  
  
• Research Highlights from 30 Years of GSI
  
  

In a recent experiment, which combined GSI's fragment seperator FRS and the experimental storage ring ESR, bound beta decay was directly observed for the first time. Bound beta decay is the time-mirrored process of orbital electron-capture decay. In bound beta decay the electron, generated in the decay of the mother nucleus, is bound in an inner atomic shell (predominantly the 1s-shell) of the daughter atom. The experiment was performed with bare TI81+ions stored and cooled in the ESR. Using Schottky mass spectroscopy, the decay of the mother nucleus and the feeding of the bound beta daughter Pb81+ could be measured simultaneously. More...



View into a dipole and quadrupol magnet of the ESR

by the SHIP-collaboration, the even-even nucleus 270-110 was synthesized for the first time. The investigation of such heavy even-even nuclei provides rather clear data for a comparison with theoretical predictions. Due to the absence of unpaired nucleons, alpha decay and/or spontaneous fission are unhindered, and the low energy level scheme is expected to be comparatively simple.The reaction Ni64+Pb207 was used to produce the new nucleus. A total of eight decay chains were observed during one week of irradiation time. From the number of events and the integrated beam dose a production cross-section of about 13 pb was deduced. More...




Decay chains observed in the production of 270-110. The left chain, which starts with longer-lived alpha-decay, is attributed to the decay of a high spin K isomer in 270-110; the right chain is consistent with the decay of the short-lived ground state.

In an experiment performed at GSIs KAOS spectrometer, the Coulomb breakup of B8 into Be7 was investigated. The experiment allowed the cross section for the inverse reaction, the production of B8+gamma from Be7+p, to be deduced, which is usually parametrized by the astrophysical S17-factor - the index indicates the mass numbers of the reaction partners proton and Be7. The S17-factor is a key parameter for predicting the high energy component of the solar neutrino flux. The deduced S17-values agree with the presently adopted S17-factor obtained from capture experiments and with the result from a recent Coulomb break-up experiment performed at lower energies. More...



Schematic view of the experimental set-up at the KAOS spectrometer. The B8 beam enters from the left and hits the Pb208 break-up target. the outgoing protons and Be7 fragments are detected in two pairs of position-sensitive silicon detectors before, and in two multiwire-proportional chambers after the detector. The TOF-wall serves as a trigger detector. The non-interacting B8 projectiles hit only the right-hand part of the TOF wall.

During the past two years, visitors to the HADES cave at GSI could follow the evolution of the High Acceptance Di-Electron Spectrometer from a lone superconducting torus magnet to an impressive array of advanced detectors. These detectors, along with an international collaboration of scientists and engineers, are now poised to begin a physics program that will serve as one of GSI's major experimental endeavors over the next several years. HADES intends to explore the properties and behavior of hadrons in the nuclear medium by studying collisions ranging from pions and protons as projectiles to heavy nuclei. Observables include the masses, decay widths, and spectral functions of vector mesons, which decay into electron-positron pairs (di-electrons) while in the dense nuclear medium of the collision. Pion and proton beams are useful for studying these mesons at normal nuclear density, while the fireball formed in collisions of heavy nuclei permits the study at higher densities. These collisions represent an intermediate region of the QCD phase diagram between the conditions of the early universe and those found in the interiors of neutron stars. Di-electrons are well-suited probes for studying in-medium hadron properties, since they do not interact with the surrounding nuclear matter and leave the reaction zone nearly unhindered. More...



A look inside the HADES detector. Two coil casings of the 6fold superconducting magnet are in the foreground, while the RICH mirror’s black carbon fiber shell is located on the right. Also visible are the long, black scintillators of the time-of-flight walls, as well as 5 of the 6 pre-shower sectors. In front of and behind the toroidal magnetic field multiwire drift chambers (MDCs) for particle tracking will be installed. A support frame for one sector of MDC3 is already in position behind the lower coil case.




Research Highlights from 30 Years of GSI

In everyday life the matter which surrounds us seems to be continuous. Only by physics methods a hierarchy of structures becomes visible. Many solid bodies have a crystalline or polycrystalline structure. If we look closer at matter, we realize that these crystals are made of atoms; looking closer at atoms we discover that they have electron shells and an atomic nucleus. The nucleus itself again consists of nucleons, positively charged protons and electrically neutral so-called neutrons. Since the 1970’s we know that also nucleons have a substructure. Together with the well known electrons these particles—dubbed quarks—are considered today to be the elementary building blocks of matter. The research program at GSI includes work in all these areas. More...



The various hierarchies in the structure of matter. Every hierarchy level is characterized by typical dimensions. Quarks and electrons are, according to the present level of knowledge, considered the elementary building blocks of matter.