The KATRIN superconducting magnets: overview and first performance results

Abstract

The KATRIN experiment aims for the determination of the effective electron anti-neutrino mass from the tritium beta-decay with an unprecedented sub-eV sensitivity. The strong magnetic fields, designed for up to 6 T, adiabatically guide β-electrons from the source to the detector within a magnetic flux of 191 Tcm2. A chain of ten single solenoid magnets and two larger superconducting magnet systems have been designed, constructed, and installed in the 70-m-long KATRIN beam line. The beam diameter for the magnetic flux varies from 0.064 m to 9 m, depending on the magnetic flux density along the beam line. Two transport and tritium pumping sections are assembled with chicane beam tubes to avoid direct “line-of-sight” molecular beaming effect of gaseous tritium molecules into the next beam sections. The sophisticated beam alignment has been successfully cross-checked by electron sources. In addition, magnet safety systems were developed to protect the complex magnet systems against coil quenches or other system failures. The main functionality of the magnet safety systems has been successfully tested with the two large magnet systems. The complete chain of the magnets was operated for several weeks at 70% of the design fields for the first test measurements with radioactive krypton gas. The stability of the magnetic fields of the source magnets has been shown to be better than 0.01% per month at 70% of the design fields. This paper gives an overview of the KATRIN superconducting magnets and reports on the first performance results of the magnets.

First operation of the KATRIN experiment with tritium

“…This stability meets the requirements of the final KATRIN design and contributes a negligible systematic effect for the FT analysis. A detailed description of the monitoring of the magnet system of KATRIN and its performance can be found in [50].…”

$$\upbeta $$-Decay spectrum, response function and statistical model for neutrino mass measurements with the KATRIN experiment

“…A segmented detector (f) acts as a counter for the transmitted signal electrons tium flow by 14 orders of magnitude [31,32]. The β-electrons are guided through the entire beamline by a magnetic field [33] into the pre-spectrometer (d), which acts as a pre-filter that blocks the low-energy electrons of the β-spectrum [34]. The energy analysis around the endpoint region takes place in the main spectrometer (e), which is operated under ultrahigh vacuum conditions [35] at a retarding voltage of about −18.6 kV.…”

Time-dependent simulation of the flow reduction of D2 and T2 in the KATRIN experiment

“…The superconducting magnets surrounding the beamline provide a guiding field of up to 5.5 T [11]. A passive magnetic shield encases each TMP to prevent eddy currents from heating up, and possible crashing, of the fast-moving rotors [12].…”

“…The beam tube elements of the CPS are subdivided into seven sections with a total length of roughly 7 m (inner diameter: ≥75 mm) and two pump ports. Each section is surrounded by a superconducting solenoid that produces the 5.6 T magnetic field [11] to guide β-electrons adiabatically through the CPS. The second and fourth beam Figure 3: CAD drawing of the CPS cryostat in 3/4 section.…”