ECHo Mainz

Tom Kieck wins poster prize at Neutrino 2018 conference

Tom Kieck, PhD student with Prof. Klaus Wendt in the ECHo Mainz team, is one winner of the poster competition at the Neutrino 2018 conference in Heidelberg. The poster topic is "Production, Separation and Implantation of ¹⁶³Ho for Neutrino Mass Measurements". Conference website

Posterprize winners at the Neutrino 2018 conference — Poster prize ceremony at the Neutrino 2018 conference. The prize winners Aurélie Bonhomme, Katarzyna Frankiewicz, Julieta Gruszko, Joseph Johnston and Tom Kieck among others with the Nobel Prize winner Takaaki Kajita.

AMS of Ho-163/Ho-166m at DREAMS facility (HZDR)

Development of AMS at DREAMS for experimental determination of the ratio ¹⁶³Ho/^166mHo in ECHo samples. The long-lived ^166mHo is an unwanted by-product of the ¹⁶³Ho production, which is reduced to ultra-low levels (10^-9) after sophisticated mass separation. For a background-free measurement of the ¹⁶³Ho spectrum in the ECHo metallic magnetic calorimeters the absence of ^166mHo is critical. DREAMS website

ECHo team measuring at DREAMS — From left to right: Felix Wiescher (JGU Mainz), Oliver Forstner (FSU Jena & HI Jena), Christoph Düllmann (GSI Darmstadt, JGU Mainz, HI Mainz), Holger Dorrer (JGU Mainz), Klaus Wendt (JGU Mainz), Silke Merchel & Georg Rugel (HZDR, HI Freiberg) and Tom Kieck (JGU Mainz).

Overview of the ECHo experiment published in Eur. Phys. J. Special Topics

EPJ ST cover - ECHo — L.Gastaldo *et al*., *The electron capture in 163Ho experiment – ECHo* Eur. Phys. J. Spec. Top. 226, 1623-1694 (2017)

Samples prepared at Johannes Gutenberg University Mainz facilitate direct measurement of the mass difference of Ho-163 and Dy-163 to solve the Q-Value puzzle for the neutrino mass determination

Using samples of ¹⁶³Ho that were prepared at the Institute for Nuclear Chemistry at the Johannes Gutenberg University Mainz, the atomic mass difference of ¹⁶³Ho and ¹⁶³Dy has been directly measured with the Penning-trap mass spectrometer SHIPTRAP at GSI Darmstadt by applying the novel phase-imaging ion-cyclotron-resonance technique. Our measurement has solved the long-standing problem of large discrepancies in the Q value of the electron capture in ¹⁶³Ho determined by different techniques. Our measured mass difference shifts the current Q value of 2555(16) eV evaluated in the Atomic Mass Evaluation 2012 by more than 7σ to 2833 (30stat) (15sys) eV/c². With the new mass difference it will be possible, e.g., to reach in the first phase of the ECHo experiment a statistical sensitivity to the neutrino mass below 10 eV, which will reduce its present upper limit by more than an order of magnitude. The results were published in Physical Review Letters on August 05, 2015 (S. Eliseev et al., Physical Review Letters 115, 062501 (2015)).

¹⁶³Ho was produced by intense neutron irradiation of ¹⁶²Er at the high-flux reactor at the Institute Laue Langevin at Grenoble, France and subsequently purified by using radiochemical separation techniques similar to those also used in research on the heaviest elements.

More information:

• ECHo Collaboration website
• University of Mainz press release
• Press release of the Max Planck Institute for Nuclear Physics in Heidelberg on idw
• here on this website
• on the GSI website

Holger Dorrer with produced and separated Ho-163 sample. — Holger Dorrer from Johannes Gutenberg University Mainz on the platform of the research reactor TRIGA Mainz that was used to verify the purity of the sample. He holds the produced and separated ¹⁶³Ho.
Credit: H.-M. Schmidt / JGU Mainz

Q-values of Ho-163 — Comparison of values reported for the Q-value of the ¹⁶³Ho electron capture decay over time.
Credit: ECHo collaboration

ECHo Mainz on the cover of Eur. Phys. J. A

Cover of EPJ A — Our article by F. Schneider *et al*., published in Eur. Phys. J. A 51, 89 (2015) on *preparatory studies for high precision mass measurements of ¹⁶³Ho for ECHo* were featured on the cover of the containing issue.