Project Details
Projekt
Production of 163Ho and Preparation of High-purity 163Ho Samples
Applicant
Professor Dr. Christoph Düllmann
Subject Area
Nuclear and Elementary Particle Physics, Quantum Mechanics, Relativity, Fields
Term
from 2015 to 2022
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 254114301
For the ECHo project, mg-amounts of radiochemically ultrapure 163Ho samples are needed. These are produced at ILL Grenoble via neutron-irradiation of enriched 162Er. Before irradiation, trace impurities of elements lighter than Er are chemically removed at Institute of Nuclear Chemistry, Mainz U., to avoid production of unwanted radioactive byproducts. After irradiation, high performance liquid chromatography serves to isolate the produced Ho. This consists mostly of 163Ho, but also of some 165Ho and 166mHo, the production of which during irradiation cannot be fully suppressed. The 163Ho is isolated via Resonance Ionization Mass Separation at the RISIKO mass separator, Institute of Physics, Mainz U. By installing chips containing Magnetic Metallic Calorimeter (MMC) arrays in the RISIKO focal plane, sample purification via mass selection, and enclosing the 163Ho directly in the detector absorbers via ion-implantation, are achieved in a single, highly efficient step. After the development of this general working scheme within the first Research Unit phase, the main tasks of Working Group 1 within the second project phase include: (i) 163Ho production run at ILL, chemical separation of Ho, and sample characterization; (ii) chemical preparation of 163Ho samples for RISIKO, for Pentatrap, and for Accelerator Mass Spectrometry (AMS) measurements to experimentally verify the absence of 166mHo; (iii) adaptation of the RISIKO implantation stage for full wafer handling to ensure that the implantation of the significant amounts of 163Ho into the ECHo-100k MMC arrays is performed at the required quality level; (iv) improvement of in-situ pulsed laser deposition (PLD), which is needed to alleviate the effects of sputtering of up to 30 atoms from the implantation substrate by each incoming 163Ho ion; (v) installation of a fast electrostatic beam gate at RISIKO, which is operated synchronized with the 10 kHz laser repetition rate and serves to suppress particles ionized outside of the ion source region and hence traversing RISIKO outside the time window of the desired ions; this allows suppressing 166mHo background by a further factor of 10-100; (vi) adaptation and upgrade of the RISIKO ion source for higher beam currents and selectivity; (vii) experimental determination of the 163Ho:166mHo ratio in MMCs via AMS at the DREAMS facility, Helmholtz-Zentrum Dresden-Rossendorf; (viii) implantation of the ECHo-100k chips to acquire the high-statistics 163Ho spectrum; (ix) establishing recovery of 163Ho lost in RISIKO between the ion source and the MMCs for beyond ECHo-100k; this will likely be more cost-efficient than a linear upscaling of reactor production of 163Ho for "once-through" cycles. Due to the long time-scale associated with the production of mg-amounts of 163Ho, this has to be started within the second project phase to ensure the long-term success of ECHo.
DFG Programme
Research Units
Co-Investigator
Professor Dr. Klaus D.A. Wendt
