Troitsk nu-mass

Unique Scientific Setup, INR RAS

Troitsk nu-mass overview

Institute for Nuclear Research Russian Academy of Sciences
Head: academician RAS, Tkachev Igor I.
Moscow, Troitsk, Fizicheskaya str, 27

Goal of the research

The device is designed for precise measurement of the beta spectrum from decays of tritium to search for sterile neutrinos in the mass range up to 5-6 keV, possibly up to 7 keV, in the absence of additional systematic effects. The range of several keV is especially interesting from the point of view of explanation dark matter in the form of the of warm weakly interacting particles (WIMP). Tthe nature of dark matter, and search for evidence of its existance are among the most important areas of research in modern physics and cosmology.

13.7 Mlrd 13.7 Mlrd
One of the theories for evolution of the Universe

The project offers an extension of the research program at the Troitsk Nu-Mass facility in the INR RAS in search for an exotic particle - sterile neutrinos.

The two main components of the experiment are the gaseous source and the electromagnetic spectrometer. The gaseous source of hydrogen isotopes helps to avoid extremely undesirable effects of distortion of the electron spectrum from implanted or frozen sources.Electrostatic spectrometer with magnetic adiabatic collimation has currently the world's best energy resolution of about 0.3 electron volts for 18 keV electrons.

The setup includes a cryogenic helium liquefaction system up to 50 liters of liquid helium per hour and cost in modern prices of about 2 million euros.

The setup is equipped with a large amount of various cryogenic and vacuum systems, experimental stands, recording electronics and computer systems.

Primary advandages of the setup

The Troitsk nu-mass experiment currently does not have analogues, both in Russia and in the world. The most tight upper boundary of the neutrino mass were obtained in this experiment. These results are of a fundamental nature and have been included in all modern bases data on the properties of elementary particles. Annually publication with these results are cited 50-60 times. The uniqueness of the installation is determined by two main components: the windowless gaseous tritium source and thw electrostatic spectrometer with a magnetic adiabatic collimation. All components of the exeriment are unique developments of Soviet and Russian scientists. Tritium source allows to work with gaseous tritium, while maintaining the conditions of high vacuum in other parts of the installation. Electrostatic spectrometer 10 meters long and about 40 cubic meters in volume has the world's best energy resolution of about 0.3 electron volts for electrons with an energy of 18 keV.

The cryogenic equipment includes a cryogenic helium liquefaction system from LINDE (Germany) for about 2 million euros. The system provides liquid helium not only needs of the experiment, but also scientific organizations in the city of Troitsk.

All elements of the installation - vacuum and cryogenic systems - are equipped with modern computer control equipment for slow control of the vacuum, temperatures and gas composition parameters of the source.

Modern electronics is used to record and collect measurement data. In addition, the experiment includes a number of vacuum stands, which are used to test individual vacuum vessels and to develop and test new types of particle detectors.

Mounting of spectrometer inner electrode:
Сборка спектрометра


The installation includes the following scientific equipment:
A windowless gaseous source of hydrogen isotopes, a magnetic electrostatic spectrometer, a cryogenic complex with a helium liquefier, vacuum test benches in two experimental halls. In addition, a precision electron gun with an electron energy of up to 35 keV is installed in the back of the gas source, which is capable of "firing" simultaneously through the source and the spectrometer.

In addition to the main equipment, the experiment has two vacuum test benches equipped with the necessary electronics and computer readout system.

A windowless gaseous tritium source with a closed circulation of working gas; 5 meters long internal superconducting solenoids during installation:


Integral electrostatic spectrometer with magnetic adiabatic collimation, MAC-E filter:

1 - spectrometer supports, 2 - source-side and detector-side cups, 3 - warm axial coils, 4 - main high-voltage electrode, 5 - electrodes under zero potential, 6 - detector system with liquid nitrogen cooling, 7 - set of superconducting magnets.

Cryogenic complex with helium liquefier LINDE and compressor station:

Linde компрессор

An electron gun with an energy of up to 35 keV and a resolution of 0.3 eV, located in the far part of the gaseous source:


One of the rooms is equipped for vacuum equipment testing:


Vacuum chamber for test measurements during installation:


According tho the safety regulations, the installation includes a system of cold and hot water supply, as well as heating of the experimental halls during the cold period.

Primary research

Search for new phenomena outside the Standard Model of elementary particle physics, search for sterile neutrinos in a cosmologically interesting mass region, development of experimental techniques and software for direct measurement of neutrino mass.

The project is aimed at direct laboratory searches for sterile neutrinos. The importance of this kind of experiments in addition to the constraints arising from different theoretical models is undeniable. The specific task is to significantly improve existing restrictions on the mixing angle of sterile and active neutrinos in the mass range from tens of eV and up to 15-17 keV. This range of mass values ​​is not available in oscillatory experiments planned in a number of world scientific centers.

An essential advantage of the installation is the presence of a gaseous source of hydrogen isotopes. This type of source avoids the extremely undesirable effects of distortion of the electron spectrum from implanted or frozen sources. We plan to perform a precise measurement of the spectrum of the beta decay of tritium in the whole kinematically accessible energy region, in contrast to the earlier measurements near the boundary point. The laboratory has extensive experience in this installation. In 2013, significant modernization of individual plant elements and the entire power supply system was completed.

The collaboration started calibration and testing of a new generation of silicon detectors with a structure of charge carrier drift. Detectors are multi-pixel and have very small capacity, at the level of dozens of femtofarads, which allows to drastically reduce noise level. The thin entrance window allows one to drop to an energy of 1-2 keV for the incident electrons. Detectors are developed at the Max Planck Institute in Munich, Germany. An agreement has been signed for joint work on this project. The Troitsk nu-mass experiment has unique sources of electrons, including electrons from the decay of tritium, which was the determining factor for these joint works.

In parallel with the main project for the search for sterile neutrinos, a compact solid-state source is being developed for a new generation of experiments. In particular, it is promising to develop a solid, safe source of tritium based on graphene. Hydrogen sources on graphene, in general terms, are considered as an option for the safe storage of hydrogen as a new generation fuel.

The collaboration has achieved the unsurpassed best limitation on the mass of electron neutrinos:


International collaboration

The studies carried out on the installation itself are related to international cooperation. The first direction is determined by the research program already carried out in Troitsk by measuring the mass of the electron neutrino in the beta decay of tritium. The KATRIN experiment currently being launched in Karlsruhe, Germany uses the same layout as the "Trinity nu-mass" experient and copies major technological know-hows developed by the group. It is an improved extended copy of our installation and will allow to improve the sensitivity of measurements by approximately an order of magnitude, reaching a limit of 0.2 eV for the mass of electron neutrino. The protocol on cooperation between Technological University of Karlsruhe and INR RAS was signed. Our staff was directly involved in the project. An inestimable work experience on installations of this type was transferred. In 2018, we plan to participate in the joint launch of the KATRIN experiment.

The second area of ​​cooperation is associated with the development of the detecting system of electrons in the "Troitsk nu-mass" experiment alongside with the Max Planck Institute of Physics in Munich. The essence of this work is development and testing of a new generation of detectors: drift silicon detectors. Detectors are being developed in Munich, electronics readout - in Italy, calibrated, testing and real measurements - in Troitsk. Two successful calibration session were performed in Troitsk with the participation of a group of colleagues from Munich.

A joint photo in June 2017 after the first successful tests of the prototype of a silicon drift detector.

Troitsk and Munich teams


List of typical services provided

In addition to the main scientific activity related to the precision measurements of the electron spectrum in the decay of tritium, it is possible to perform other works and services at the facility:

  • Investigation and precision measurement of the emission spectra of electrons from gaseous and solid substances in the energy range from 5 to 30 keV.
  • Study of electron scattering by means of a precision electron gun on gaseous samples.
  • Testing of elementary particle detectors in vacuum chambers using different types of sources, including tritium. It is possible to provide high vacuum and cryogenic temperatures.

When performing work for the benefit of outside organizations, the calculation is carried out in the hours of operation of the whole setup or its parts. At the same time, the cost of services includes the payment for employed personnel, the cost of the necessary materials (for example, liquid nitrogen and gaseous helium, if the work is related to the use of cryo equipment) and preliminary technical work, electricity, heating, etc.

It should be noted that it is possible to obtain bachelor and master degrees in the field of experimental and applied nuclear physics under the guidance of qualified specialists in our experiment.

Regulations for access to the unique scientific setup

External castomers are required to fill an application form, which indicates the essence of the planned work or the required experimental developments, information about the customer, as well as other information needed for planning the use of equipment. The status of consideration of the application can be checked on this site. After consideration of the application and in the event of its adoption, a civil law contract should be signed on the performance of work or the provision of services.

The procedure for calculating the cost of non-standard services

The calculation will be made depending on the type and conditions of the provision of services.

Request form

In order to request facility services, submit the following form:

Plans and development

In accordance with the preliminary plans and according to incoming applications in 2019, it is planned to conduct two measurement sessions. The beginning of the first session on April 9, 2019, the end on April 28.
The main work will be devoted to the development of a measurement technique with a multi-pixel silicon drift detector and a set of statistics on the search for sterile neutrinos.

Personnel of the installation

The team of the group working on the plant is 12 highly qualified specialists. Of these, 5 people has phd degree, 3 engineers in cryogenic engineering, several researchers, 2 mechanics. The device can work up to 2000 hours per year (in case of appropriate funding).

Educational capacity of the installation

The experiment provides unique educational opportunities for engineers and physicists, since students and graduate students can not only solve the specific problems they are working on, but also study many aspects of physics and engineering, such as vacuum technology, cryogenics, electronics and much more. At the moment two students of MIPT and one graduate student of INR are involved in the research.


INR RAS: prospekt 60-letiya Oktyabrya 7a, Moscow 117312

Troitsk subdivissuion: ul. Fizicheskaya 27, Moscow, Troitsk 108840

Tel: +7(495)850-42-01,

Head of the project, academician RAS Igor Tkachev, e-mail:

Contact person, prof. dr. Vladislav Pantuev, e-mail:

2010 photo with the founder and former leader of the experiment academician Vladimir Lobashev:

Members ofTroitsk nu-mass II experiment at 2010