Working Groups - Projects

WG1: Production of 163Ho and Preparation of High-Purity 163Ho-Sources

Christoph Düllmann, Klaus Eberhardt

High purity 163Ho-samples are prepared from neutron-irradiation of Er enriched in 162Er. Prior to irradiation in a high flux reactor, Er is separated from all lighter lanthanides. After irradiation, Ho is isolated from the irradiated sample by removing all activation products resulting from heavier lanthanide elements. This allows producing samples containing only Ho. To remove the disturbing 166mHo, which is co-produced in the neutron-irradiation, laser resonance ionization and mass separation either at the RISIKO mass separator at Johannes Gutenberg University Mainz or at the ISOLDE GPS mass separator at CERN are performed, allowing the production of radiochemically pure 163Ho samples.

WG2: Low Temperature Detectors and Data Analysis

Loredana Gastaldo, Christian Enss

The main objectives are the design, the optimization and the fabrication of the detector arrays together with WG3 and in addition the developement of online data anlysis. In parallel experiments where the 163Ho is embedded in different absorber materials will be performed. The main goal of these measurements is to look for possible solid-state effects. Following the results achieved by WG4 we will in addition perform experiments for background identification and reduction and will develop methods for the analysis of the spectrum, which reduce the presence of systematic errors and enhance the sensitivity to a non-zero neutrino mass at the end-point region of the spectrum.

WG3: Microwave SQUID Multiplexing and Cryogenics

Christian Enss, Sebastian Kempf

The investigation of the electron neutrino mass with 10 eV sensitivity by means of a MMC based calorimetric measurement of the 163Ho EC spectrum requires the simultaneous operation of about 100 detectors for a period of about one year. To accommodate constraints on system complexity, wiring and heat load, a μMUX in combination with a digital SDR system will be developed to simultaneously read out the detectors. Both, the multiplexer and the detectors, will be placed at the cold stage of a customized pulse tube precooled dilution refrigerator being very well suited for continuously providing a cryogenic environment in the mK range with only short maintenance intervals.

WG4: Background Analysis and Background Control

Joseph Jochum

The goal of the project is to reduce and control the background in the ECHo experiment sufficiently to achieve a non pile-up background of less than 10-5 counts/eV/day/detector at the endpoint of the 163Ho EC decay. Crucial feedback about the radiopurity is going to be provided to the other working groups, especially WG3 requires the data of the material screening for the design and the construction of the cryostat and the internal shielding.

WG5: Measurement of QEC by Penning-Trap Mass Spectrometry

Klaus Blaum, Sergey Eliseev

The objective of the project is a determination of the QEC-value of the electron capture in 163Ho with an uncertainty of a few tens of eV with the Penning-trap mass spectrometer SHIPTRAP. In order to reach this goal, it is essential to apply the novel PI-ICR technique. Furthermore, this measurement must be preceded by an extensive test of the 163Ho ion production with a laser ablation ion source at the Penning-trap mass spectrometer TRIGATRAP.

163Ho EC-Spectrum
Prof. Dr. Christian Enss
phone +49 (0)6221 54-9861
JProf. Dr. Loredana Gastaldo
phone +49 (0)6221 54-9884