Space Radiation Physics
Group leader: Dr. Uli Weber
Radiation represents a significant hazard in all space explorations, especially outside the protective shield of the Earth’s magnetic field. Solar and galactic particle radiation consists primarily of protons and helium ions, but the relatively small number of heavier ions in the galactic cosmic radiation (GCR) can significantly contribute to radiation dose due to their high ionization energy loss. In humans, genetic alterations, cancer, and cataracts may already be induced by low levels of radiation. There is also the potential for damage to space instrumentation, as the high charge locally deposited by energetic heavy ions can produce changes in computer chips and other electronic devices; frequently observed changes of the status of memory units are a prominent example. Because shielding is difficult and costly in space, the effects of the cosmic radiation should be known as accurately as possible in order to optimize the shielding measures and to exploit the shielding properties of materials used for other purposes, such as the spacecraft hull, internal equipment, fuel and supplies.
The GSI accelerator facilities offer world-wide unique possibilities for the simulation of cosmic radiation, in particular the galactic cosmic radiation (GCR), which – besides the most abundant protons and helium nuclei – also includes heavier nuclei up to the actinides. The accelerators UNILAC and SIS-18 deliver ion beams of high quality of many chemical elements (including iron which plays an important role) in the energy range of 1 MeV to 1 GeV per nucleon. Light ions (up to neon) can be accelerated up to 2 GeV per nucleon. This spectrum covers an interesting part of the GCR with the maximum particle fluence at several 100 MeV per nucleon.
Furthermore, the FAIR accelerator complex at GSI will be a unique facility, where heavy ions with energies up to 10 AGeV can be used for radiobiology and materials research.
This will dramatically extend the energy range of GCR radiation that can be investigated in a ground based facility. As part of the FAIR project the BIOMAT laboratory will enable a wide spectrum of experiments at high GCR energies.
Main research topics
- Radiobiology
- Outside the protective magnetic field of the earth astronauts in space are fully exposed to solar and cosmic radiation. Genetic alterations and cancer may already be induced by low levels of radiation. Because of their high local energy deposition heavy nuclei contribute significantly to the radiation risk. Therefore, systematic investigations of radiation damage and risk assessment are indispensable for long-term space missions.
- Shielding
- Space radiation is generally acknowledged as the main potential showstopper for long duration manned interplanetary missions. The most important countermeasure for reduction of space radiation exposure is shielding, as the other parameters (distance from the source and time exposure) are not applicable for long interplanetary missions. Aluminium spacecraft structures make very poor shields for human occupants, not only because they hardly attenuate any incoming high energy radiation, but also because the secondary radiation produced by the impact of GCRs on the nuclei of the Al atoms in the structure add to the radiation incident on the astronauts. Therefore the investigation of shielding concept with appropriate materials is an important contribution for future space missions. Goals of the research for shielding materials @ GSI:
- To analyse and model the mechanisms of interaction, deflection and attenuation of high energy charged particles (HECPs) in different shielding materials.
- To develop new compositions and structures of shielding materials for best possible protection of humans against high energy Galactic Cosmic Rays.
- Tests and calibrations of space flight instruments
- The High-energy irradiation facility Cave A offers excellent conditions for testing and calibrating detectors designed for the exploration of cosmic radiation in space. Important parameters such as mass- and charge resolution or isotope separation capability of spectrometers can be determined and the performance of data analysis software can be verified under realistic conditions on ground.
Detector systems of the space missions MAGPIE, SOHO, ACE, ALTEA and others were tested and calibrated with high-energy ion beams at GSI.
- The High-energy irradiation facility Cave A offers excellent conditions for testing and calibrating detectors designed for the exploration of cosmic radiation in space. Important parameters such as mass- and charge resolution or isotope separation capability of spectrometers can be determined and the performance of data analysis software can be verified under realistic conditions on ground.
- Radiation hardness of electronic components
- In space complex electronic devices such as microprocessors, storage-chips or other large-scale integrated systems are exposed to cosmic radiation. This may result in malfunction or even loss of data. For example, storage chips for the European Space Agency (ESA), microprocessors (IBM) and other electronic components of satellite missions and astrophysical experiments (e.g. the AMS-Experiment or the Italian ALTEA-project) on board of the International Space Station (ISS) were successfully tested at the irradiation facility Cave A at GSI.
Radiation Physics
The group provides a service (dosimetry) to users of the accelerators, and performs an independent research activity bridging nuclear and medical physics. Furthermore, this group performs nuclear physics experiment to measure double-differential fragmentation cross-sections for ions and energies of interest for particle therapy and space radiation protection.
Main research topics
- Nuclear fragmentation
- Fragmentation of different ions in thick water targets
- Double differential cross sections, elastic and non-elastic scattering
- Beam modulation experiments
- Ripple filters
- 3D range modulators for extremely fast ion-beam therapy
- In vivo dose monitoring
- Online PET
- Prompt gamma emission
- Particle emission
- Out-of-field dose measurements
- Microdosimetry spectra (T-PEC micro dosimetry chamber)
- Neutrons and stray radiation in phantoms
- Shielding
- Primary beam attenuation (Bragg curves)
- Neutron production
- FAIR
- Plans for the new BIOMAT Cave at FAIR
Collaborations
- TIFPA Trento Institute for Fundamentals Physics Applications (Prof. Marco Durante)
- Brookhaven National Laboratory (Dr. A. Rusek)
- THM Technische Hochschule Mittelhessen (Prof. Klemens Zink)
- University Clinic Marburg (Prof. Engenhart-Cabillic)
- CNAO Centro Nazionale di Adroterapia Oncologica (Dr. Sandro Rossi)
- DLR (Dr. G. Reitz)
- HZDR-Oncoray (Dr. W. Enghardt)
- University of Lyon (Dr. E. Testa)
- PSI (Dr. T. Lomax)
- PTB (Dr. H. Weissmann)
- University of Rome (Prof. V. Patera)
- JLU Justus Liebig University Gießen (Prof. Kai Brinkmann)