How much does a neutrino actually weigh? Billions of these mysterious elementary particles fly through us every second, but they hardly ever interact with matter and therefore remain unnoticed. Admittedly, I haven’t asked myself this question very often either. And at first glance, it might not seem that relevant. However, the conclusions that can be drawn from determining the mass of neutrinos, which was successfully achieved in the KATRIN experiment at the Karlsruhe Institute of Technology (KIT), are nothing short of astonishing. Read more about them in this issue.

Also: The international scientific community is concerned about access to data stored in the US. A viewpoint from Susanne Buiter, Scientific Director of the GFZ Helmholtz Centre for Earth System Research Berlin.

Enjoy reading!

Neutrinos are among the most enigmatic particles in the universe. Though omnipresent, they almost never interact with matter. In cosmology, they influence the formation of large-scale galactic structures, while in particle physics, their minuscule mass serves as an indicator of previously unknown physical processes. Accordingly, precisely measuring neutrino mass is essential for a complete understanding of the fundamental laws of nature.

This is precisely where the KATRIN experiment and its international partners come into play. KATRIN utilizes the beta decay of tritium, an unstable hydrogen isotope, to measure neutrino mass. The energy distribution of the electrons resulting from the decay allows a direct kinematic determination of the neutrino mass. Achieving this requires highly advanced technical components: the 70-meter-long beamline houses an intense tritium source, as well as a high-resolution, 10-meter-diameter spectrometer. This cutting-edge technology affords an unprecedented level of precision in direct neutrino mass measurements. 

With the current data from the KATRIN experiment, an upper limit of 0.45 electronvolts (eV)/ c2 (corresponding to 8 x 10-37 kilograms) could be derived for neutrino mass. Compared to the last results from 2022, the upper limit could thus be reduced by nearly a factor of two.

Further, the researchers are optimistic about the future: “Our measurements of neutrino mass will continue until the end of 2025. Through the continuous improvement of the experiment and analysis, as well as a larger dataset, we expect to achieve even higher sensitivity – and possibly make groundbreaking new discoveries,” says the KATRIN team. KATRIN already leads the global field of direct neutrino mass measurements and its initial data alone has surpassed the results of previous experiments by a factor of four. The latest findings indicate that neutrinos are at least a million times lighter than electrons, the lightest electrically charged elementary particles. Explaining this enormous mass difference remains a fundamental challenge for theoretical particle physics. 

In addition to the precise measurement of neutrino mass, KATRIN is already planning the next phase. Starting in 2026, a new detector system, TRISTAN, will be installed. This upgrade to the experiment will make it possible to search for “sterile neutrinos,” hypothetical particles that interact even less than the known neutrinos. With a mass in the keV/c² range, sterile neutrinos are a potential candidate for the particles that make up dark matter. Additionally, KATRIN++ will launch a research and development program aimed at devising concepts for a next-generation experiment capable of achieving even more precise direct neutrino mass measurements. 

More about KATRIN

Chlorotonils: Game-changers in the fight against multidrug-resistant pathogen

The spread of antibiotic resistance represents one of the greatest threats to global health. To overcome this resistance, drugs with novel modes of action are urgently needed. Researchers at the Helmholtz Institute for Pharmaceutical Research Saarland (HIPS) have now unlocked the mode of action of a promising class of natural products – the chlorotonils. more

Trawling-induced sediment resuspension reduces CO2 uptake

When trawling nets are dragged across the seafloor, they stir up sediments. This not only releases previously stored organic carbon, but also intensifies the oxidation of pyrite, a mineral present in marine sediments, leading to additional emissions of carbon dioxide (CO2). These are the findings of a new study conducted by the GEOMAR Helmholtz Centre for Ocean Research Kiel. Based on sediment samples from Kiel Bight, the researchers investigated the geochemical consequences of sediment resuspension.  more

Bild: Phil Dera

Christine Mieck is a biochemist and Manager of the Information Research Field at the Helmholtz Berlin Office.

What fascinates me most is the daily collaboration with researchers, their enthusiasm and their commitment to sharing their findings with society. At the Helmholtz Head Office, I help shape the scientific cosmos from what you might call a horizontal perspective: I network disciplines and people, accompany processes, and thus support scientific excellence (on an infrastructural and strategic level). I find it particularly enriching when my input can help to establish new connections between people and disciplines, generating new and surprising findings that ultimately benefit society.

I would set up my own interdisciplinary summer school. With targeted scholarships, I would enable young scientists to participate in order to encourage them to shape science with passion, curiosity and unconventional approaches – just as I was able to do. During my academic career, a summer school in Woods Hole, a small harbor village on the US East Coast, had a profound impact on me. There, international scientists of all career levels – including Nobel Prize winners – worked side by side to isolate proteins from freshly caught squid, which we later grilled together. Intense discussions ensued over the subsequent meal, often lasting well into the night and creating a space for radical new ideas.

This unique combination of creative freedom, an open mindset, and direct mentoring by exceptional personalities creates an atmosphere that goes far beyond traditional academic formats.

I would love to have dinner with Richard Feynman – a brilliant physicist and inspiring teacher with a great sense of humor. I am fascinated by his gift for explaining complex science in a straightforward way. We would eat together, talk about his amazing life, and compare the science of today and yesterday. After dessert, we would crack the restaurant’s safe together – a hobby he picked up out of boredom during his time at Los Alamos.

Cutbacks, terminations, arrests—in countries around the world, we are currently witnessing a battle against science for ideological reasons that is reminiscent of the darkest times in Europe. The focus is on “wokeness,” “gender,” climate, and health, as well as diversity, equity, and inclusion and even science as a whole. 

In the United States of America, of all countries, the government of the world's most powerful scientific nation is at the forefront of this battle. In addition to health research, the geosciences are particularly affected because climate change and environmental protection have been declared “non-topics”, and Earth observation programmes are threatened with cuts or closure. 

This not only puts decades of partnerships at serious risk, but also valuable data sets. The environmental data service of the US National Oceanic and Atmospheric Administration (NOAA) alone lists dozens of data sets and products that are to be discontinued. These include data from earthquake catalogues and ocean currents.

This threatens to cause gaps in global measurement networks that are essential for Earth observation and thus for climate models and early warning systems. In addition, we often process scientific data in international networks on a collaborative basis, for example, sensors somewhere on Earth or in space, collect raw data which are processed by partners worldwide to be made available for other scientists. There is a worry that these processing steps may drop out.

In the Helmholtz Research Field Earth and Environment, we discuss jointly organising storage capacities, expertise, and interfaces before important data disappears irretrievably. To do this, we need not only hardware but also personnel as we cannot provide processing and access services in the long term with our existing staff.

We have for now agreed on a set of endangered data sets that we could take over and make available to the scientific community. Existing services such as PANGEA from the AWI or GFZ Data Services can help here. By increasing human resources for a transition period, we can buy time for long-term European solutions. We need redundancy (without unnecessary duplication of data sets) and embedding of new data sets and data streams into European structures. Networks and infrastructures such as ERICs (European Research Infrastructure Consortium) already exist and could be addressed.

As Germany's largest research organization, Helmholtz should be a pioneer in this area and pave the way for a path that we must follow together with other research organizations and European policymakers. To do this, we need to free up resources or raise additional funds.

Massive cuts and closures are often framed by the question of what kind of science we want to afford. In my view, this is fundamentally wrong. Instead, we must ask what data gaps and what ignorance we as a society are willing to accept. And we must point out what the consequences of this ignorance are.

As humanity, we are facing a multi-crisis of planetary proportions, alone with biodiversity loss and global warming. We are heading toward hazards that will not disappear if we close our eyes, quite the contrary.

100 years ago, when physics reinvented itself with the advent of quantum mechanics, a whole new world opened up for scientists. First, the wave-particle duality, the Schrödinger equation and Heisenberg’s uncertainty principle, used to describe the physics of atoms. Then, with the development of the Dirac equation incorporating the special theory of relativity, the prediction of antimatter, which is sometimes easy to create but doesn’t survive long in our material world. And the advances continued, one after the other: in experiments, the known particles such as electrons, protons and neutrons were joined by other, previously unknown ones – a veritable menagerie of particles. Among them was an inconspicuous type that our universe is teeming with: neutrinos. In our fourth instalment for the Quantum Year, we tag along with Kathrin Valerius from the Karlsruhe Institute of Technology (KIT) on the trail of the elusive particles.

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Published by: Helmholtz Association of German Research Centres, Anna-Louisa-Karsch-Str.2, 10178 Berlin

Editors: Sebastian Grote, Franziska Roeder, Martin Trinkaus
Questions to the editors should be sent to monthly@helmholtz.de

Photo credit: Phil Dera (Editorial)

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