First long multiplet for FAIR Super Fragment Separator in the test stand


The first long multiplet for the superconducting fragment separator (Super-FRS) of the new FAIR accelerator, produced by the company ASG Superconductors in Italy, was delivered to the test stand at the European research center CERN in Switzerland. A cooperation agreement exists between GSI/FAIR and CERN for the testing of accelerator magnets, under which the multiplet will undergo a series of detailed quality tests before delivery to Darmstadt.

A total of nine superconducting single magnets are integrated into the multiplet, and it is a real heavyweight: It is seven meters long, has a diameter of 2.5 meters and weighs over 60 tons (video of the magnet). Accordingly, the delivery to CERN was made by means of a heavy goods transport on a low loader. Following installation in the test stand, the multiplet will be cooled and subjected to extensive testing of operating parameters and magnetic field qualities, which is expected to take about six to nine months. After successful completion of the acceptance tests, the multiplet is to be transported to GSI and prepared for the subsequent tunnel installation as part of a pre-assembly. Until the final installation, the multiplet and also its successors will be temporarily stored.

The multiplets are later used in the Super-FRS to guide and shape the beam to achieve a high-precision particle beam. The Super-FRS of the future FAIR accelerator center is an important component of the overall facility with great discovery potential for science: This part of the accelerator complex is about experiments with extremely rare exotic nuclei in the framework of FAIR’s experimental pillar NUSTAR (Nuclear Structure, Astophysics and Reactions). For this purpose, ions of the heaviest elements are initially accelerated onto a material sample (target) and crushed by the impact. Among the resulting fragments are exotic nuclei, which are sorted out at the Super-FRS and made available for further experiments. With the new separator nuclei up to uranium can be produced at relativistic energies, monoisotopically separated and analyzed. Since this entire process takes only a few hundred nanoseconds, the Super-FRS allows access to very short-lived nuclei.

The multiplets produced in La Spezia, Italy, as well as the subsequent test procedure, are an important contribution (in-kind) of GSI to the FAIR project. GSI is the main German shareholder in the international FAIR GmbH. All superconducting magnets required for the Super-FRS will be tested in the new test facility at CERN in alternating sequence. This includes both the total of 32 multiplett units as well as 24 superconducting dipole magnets, which are needed for deflecting the particle beam. A first short multiplet had already been delivered to CERN in 2019, used for commissioning of the first of a total of three test stands. In the meantime, the acceptance test of the short multiplet was successfully completed despite difficult conditions due to the corona pandemic. Currently, the second test stand is being commissioned with the multiplet in preparation for series testing of all multiplets. From spring of this year, further multiplet deliveries are planned at approximately monthly intervals. (BP/CP)

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