Ten Technical Design Reports and two feasibility studies approved in 2014

FAIR paves the way for new measuring equipment

Prototype of the BELEN detector: It will allow identifying, with very high probability, each neutron passing the detector. Photo: NUSTAR BELEN Group

Schematic drawing of the CBM RICH detector: It will measure the speed of charged particles travelling at velocities close to the speed of light. With the help of the magnet and other detectors the particle species can subsequently be inferred. Source: CBM RICH Group

In the past year the FAIR GmbH approved a total of twelve concepts for measuring equipment for the future FAIR complex – so-called Technical Design Reports (TDR) – and feasibility studies for experiments at the future complex. Thus the detailed planning and financial planning can now commence.


The TDRs were drawn up by scientists working on the FAIR experiment collaborations and have been given a positive appraisal by a body of internationally acknowledged scientists, the Expert Committee Experiments (ECE). In order to construct the measuring equipment the experiment collaborations can now apply for the release of funds by the FAIR partner countries and, where applicable, for co-financing by external providers of capital.


Can nuclear material become liquid?


Among the approved concepts are a superconducting spectrometer magnet and two detectors for use in the experiments on Compressed Baryonic Matter (CBM and HADES). The magnet sorts charged particles by their momentum. It guides particles, which attain speeds close to the speed of light, into the detector. This “Ring Imaging Cherenkov Detector” comprises a chamber containing a gas. When the charged particles fly through the detector chamber, they stimulate the gas atoms along their trajectory and the gas then radiates light. This light moves more slowly than the particles in the gas. For this reason the particles are followed by a cone of light. The detector measures the size of this light cone and can thus determine the speed of the particles. One can, hence, infer on the particle species by having measured herewith the speed and momentum of charged particles. However, it is much more difficult to clearly identify electrons and, above all, uncharged particles. So as to demonstrate their existence the electromagnetic calorimeter has been approved for HADES. Scientists will analyze nuclear material at extremely high densities with CBM and HADES. They hope to find indications of a change of phase – in other words, to determine what happens when such nuclear material changes from a solid state into a liquid or gaseous state.


What holds together strongly interacting particles


For the PANDA experiment (Antiproton Annihilation at Darmstadt) a central “target” has been approved for the antiproton beam. Moreover, the committee has approved a system integrated into the iron of the magnet, which is intended to identify muons.


The target is a form of nozzle which creates tiny, equally sized, ultrapure droplets of liquid or frozen hydrogen, which fall downwards and traverse the FAIR antiproton beam. When antiprotons collide with the atom nuclei of hydrogen – with protons – the particles and antiparticles destroy one another and create pure energy. In turn this leads to the creation of particles, among which are muons, which may only be distinguished with difficulty from other much more frequently produced particles. Through the analysis of these particles the researchers can draw conclusions on the nature of the so-called strong force which holds together atomic nuclei, and thus provides the basis for the world as we know it.


Understanding processes in the universe


As part of the low-energy experiments of the NUSTAR collaboration (Nuclear Structure, Astrophysics and Reactions), which is endeavoring to understand the structure of atomic nuclei, the ECE has approved three components.


Among these is a plunger – a combination of a target, in which the short-lived nuclear states to be studied are created, and a high-precision deceleration material. In combination with the detectors of the HISPEC experiment it is possible to measure the duration of nuclear decay by means of the Doppler shift.


Two detectors have been accepted for the DESPEC experiment, which is scheduled to take place in the same experiment hall; these are intended to detect neutrons from nuclear reactions whose existences are otherwise particularly difficult to demonstrate. The BELEN detector makes it possible to measure every single neutron with a high degree of probability, while the MONSTER detector allows researchers to determine the energy of the neutrons.


A research project has attested to the considerable discovery potential of the additional experiments on the Super Fragment Separator (Super-FRS) at FAIR. These so-called Super-FRS experiments are strongly endorsed by the ECE. At present work is being conducted on the technical details for their implementation. With these experiments the scientists on the NUSTAR collaboration want to understand processes which take place in stars and exploding stars (supernovae), and thus explain how the elements we encounter daily were created.


Understanding atomic properties


In order to be able to study atomic properties the ECE has authorized a SPARC experiment by APPA (Atomic, Plasma Physics and Applications) which had previously been planned for another development stage of FAIR. In the framework of a study researchers have already demonstrated that the experiment will deliver outstanding scientific results under changed beam conditions. With this experiment, for example, extremely high electric field strengths can be created, with the aid of which conclusions may be reached about fundamental laws of physics. In addition, a TDR for a so-called Cluster Jet Target has been authorized for this experiment.


Researching material properties under extreme conditions


And last of all the construction of a series of coupled magnets was approved for the plasma physics experiments by APPA: These magnets bundle particle beams particularly tightly and can allow them to strike a material sample either as a tiny point or in a circular shape. Thus it is possible to create extremely high temperatures and pressures in the samples. In this manner scientists intend to test material properties under extreme conditions. Furthermore, it is possible to simulate the conditions inside stars.

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