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KATRIN and TRISTAN: Neutrinos and dark matter

The neutrino is one of the most fascinating particles in the Standard Model of particle physics. Despite important discoveries over the last ten years, a number of questions remain unanswered: How heavy is a neutrino? Is the neutrino its own antiparticle? Does the well-known left-handed neutrino have a right-handed partner? Investigating these unknown neutrino properties is the key to gaining a better understanding of the composition and evolution of the universe, and is the ultimate goal of the KATRIN/TRISTAN Research Group.


The Karlsruhe Tritium Neutrino experiment (KATRIN) is a large-scale experiment that is currently being commissioned at Karlsruhe Institute of Technology (KIT) whose aim is the direct determination of the neutrino mass. An international research collaboration comprising around 150 members from 17 institutes in six different countries is involved in this experiment. 

The KATRIN experiment comprises an ultrahigh-intensity source of heavy hydrogen (tritium) and a high-precision spectrometer. One electron and one neutrino are emitted during the radioactive decay of the tritium atoms in the source. The energy released in this decay is randomly divided between the two particles. However, the electron can never possess all of the decay energy, as the neutrino lays claim to at least the energy that corresponds to its mass (E = mc2).

By determining the maximum energy of the electron, it is then possible to derive the mass of the neutrino. The KATRIN spectrometer is used to measure the energy of the electron produced when the tritium decays. KATRIN started operations in June 2018, and aims to determine the neutrino mass with a sensitivity of 200 millielectronvolts over the next few years. 

Our Research Group will concentrate on the upcoming data analysis and on developing a novel detector system for KATRIN, known as TRISTAN.


Owing to its excellent source and spectrometer properties, the KATRIN experiment enables us to not only determine the neutrino mass, but also to search for a new variant of the particle: The right-handed partner of the neutrino, the so-called sterile neutrino. 

To find this particle, scientists are developing a novel detector called TRISTAN.

More information on the KATRIN/TRISTAN group

News releases

Members of the collaboration during the spring 2019 neutrino mass campaign.

Because of their extremely small mass, neutrinos play a key role in cosmology and particle physics. After evaluation of the first measurement results in the Karlsruhe Tritium Neutrino Experiment (KATRIN), it is now clear: The previously unknown mass of the neutrinos must be less than 1 electron…

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Prof. Dr. Susanne Mertens

Neutrinos are in the spotlight of particle physics: Numerous experiments are dealing with these special particles. After all, they have the potential to get at least one step closer to answering some of the major physics questions. With a new experiment, Susanne Mertens from the Max Planck Institute…

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Karlsruhe Tritium Neutrino Experiment KATRIN begins measurements – Ceremonial commissioning on June 11, 2018

Neutrinos on the world's most accurate scales

The KATRIN experiment: view of the large spectrometer. Here, scientists measure the energy of electrons emitted in Tritium decay. The energy is supposed to disclose the mass of the neutrino.

How heavy are neutrinos? This seemingly trivial question is one of the most important problems in modern particle physics and cosmology. The Karlsruhe Tritium Neutrino Experiment KATRIN, which began on June 11, 2018, aims to answer this question: it is the end result of 15 years of construction at…

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Café & Kosmos on June 26, 2018

How heavy is the Neutrino?

Inside the KATRIN experiment
Aude Glaenzer and Paul Ripoche at one of their favorite place at the MPP: the tennis court.

Aude Glaenzer and Paul Ripoche, two master students in their first year at the famous École normale supérieure de Paris-Saclay, spent four months as interns at the Max-Planck-Institute for Physics. They worked with Dr. Susanne Mertens’ KATRIN/TRISTAN group. Before they left, we asked them a couple…

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Important milestone for new neutrino experiment

KATRIN detector catches sight of its first electrons

Inside the KATRIN experiment

The KATRIN experiment recently celebrated its “first light”. The Karlsruhe Institute of Technology has announced that the detector has registered, for the first time, electrons that have initially flown through the 70-meter-long beamline. As the most precise measuring scale in the world, KATRIN’s…

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Experimental neutrino physics – this is the main topic of a new Research Group at the Max Planck Institute for Physics. The Group will is led by Susanne Mertens, who has previously worked on the KATRIN and the Majorana experiments at the Karlsruhe Institute for Technology and Lawrence Berkeley…

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Group members

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Bevilacqua, Tiziano, Dr.

Scientist 373 028C

Brunst, Tim

PhD-Student 401 030C

Edzards, Frank

PhD-Student 205 020C

Forstner, Christian

Student 364 215

Gupta, Vikas

Student 205 020C

Henkes, Florian

Student 373 028C

Hoffmann, Leander

Student 401 030C

Houdy, Thibaut, Dr.

Scientist 560 018C

Karl, Christian Robert

PhD-Student 205 020C

Kellerer, Fabian

Student 373 028C

Kholodkov, Jakov

Student 401 030C

Koehler, Christoph

Student 361 025C

Lasserre, Thierry, Dr.

Scientist 582 022C

Meier, Matthias

PhD-Student 361 25C

Mertens, Susanne, Prof. Dr.

Scientist 590 019C

Pollithy, Anna

PhD-Student 583 029C

Schlueter, Lisa

Student 419 021C

Schwemmer, Alessandro

Student 373 028C

Siegmann, Daniel

PhD-Student 401 030C

Slezak, Martin, Dr.

Postdoc 583 029C

Urban, Korbinian

Student 361 025C

Weidenthaler, Matthias

373 028C

Werner, Diana

Secretary 364 215

Wickles, Johannes Gerald

Student 361 025C

Willers, Michael

Scientist 583 029C

External members

Dr. Thierry Lasserre, ICEA, France
Dr. Julieta Gruzko, UW, USA
Dr. Alexey Lokhov, RAS, Russia

Key publications

Commissioning of the vacuum system of the KATRIN Main Spectrometer
KATRIN Collaboration
Journal of Instrumentation, Volume 11, April 2016

A White Paper on keV Sterile Neutrino Dark Matter
M. Drewes, T. Lasserre, A. Merle, S. Mertens
submitted to Journal of Cosmology and Astroparticle Physics (JCAP) (2016)

Sensitivity of Next-Generation Tritium Beta-Decay Experiments for keV-Scale Sterile Neutrinos
S. Mertens, T. Lasserre, S. Groh, G. Drexlin, F. Glück, A. Huber, A. W. P. Poon, M. Steidl, N. Steinbrink, C. Weinheimer
Journal of Cosmology and Astroparticle Physics (JCAP) 1502 (2015) 02, 020

Wavelet approach to search for sterile neutrinos in tritium beta- decay spectra
S. Mertens, K. Dolde, M. Korzeczek, F. Glück, S. Groh, R. D. Martin, A. W. P. Poon, M. Steidl
Physical Review D 91 (2015) 4, 042005

Current Direct Neutrino Mass Experiments
G. Drexlin, V. Hannen, S. Mertens, C. Weinheimer
Advances in High Energy Physics, Volume 2013 (2013)