Exotic nuclei and beams (IGISOL)

The exotic nuclei and beams group studies properties of nuclei employing a novel combination of ion manipulation techniques, mass spectrometry, laser and decay spectroscopy at the IGISOL facility. The research conducted in the group furthers our understanding of nuclear structure and provides essential data for nuclear astrophysics, neutrino physics, fundamental interactions as well as for applications.

Overview

Core fields of research

Basic natural phenomena and mathematical thinking

Research areas

Nuclear and accelerator based physics

Faculty

Faculty of Mathematics and Science

Department

Department of Physics

Research group description

The exotic nuclei and beams group exploits the universal ion guide production method at the IGISOL facility to explore short-lived exotic nuclei. In addition, our research takes place also at other laboratories, such as the ISOLDE facility in CERN, and Helmholzzentrum GSI, the location of the future radioactive beam facility FAIR. These international activities are done in close collaboration with HIP, the Helsinki Institute of Physics.

The research is strongly supported by the Research Council of Finland (RCF), with several research projects ongoing. Dr. Mikael Reponen is leading the experimental part of the "Nuclear properties at the N=Z line (NUANZ)" project 2025-2029. While NUANZ focuses on laser spectroscopy, Academy research fellow Zhuang Ge's project "Mass measurements of exotic N=Z nuclei (up to 100Sn) and the vicinity for nuclear physics and nuclear astrophysics studies" (2023-2027) provides information on masses. Prof. Anu Kankainen is leading "Heavy Exotic Nuclei for Nuclear Astrophysics" (2023-2027) RCF project. In 2026, she will start her academy professorship project "Nuclei – the Structure and Origin of Matter" (2026-2031). She also leads a research team in the new RCF Centre of Excellence (CoE) in Neutron-Star Physics (2026-2033).

We also benefit from the Euratom Research and Training Programme (EURATOM) which funds the "Addressing PRiorities of Evaluated Nuclear Data in Europe" (APRENDE) project (2024-2028).

Selected publications

IGISOL Portrait - three decades of research. The "IGISOL Portrait - three decades of research" is a collection of articles describing the research conducted using the ion guide technique at IGISOL.

Ion traps in nuclear physics—Recent results and achievements. T. Eronen, A. Kankainen, and J. Äystö, Progress in Particle and Nuclear Physics 91, 259-293 (2016). [Open Access: JYX]

Laser spectroscopy for nuclear structure physics. P. Campbell, I.D. Moore and M.R. Pearson, Progress in Particle and Nuclear Physics 86, 127-180 (2016) [Open Access: JYX]

Research

Nuclear Astrophysics

Almost all chemical elements have been created via nuclear reactions in stars. The multimessenger observations, the gravitational wave event GW170817 and its electromagnetic counterparts, gave the first direct evidence that elements heavier than iron are created via the rapid neutron capture process (the r process) in a merger of two neutron stars. New fascinating observations are anticipated in coming years. In order to understand and model the r process in detail, precise data on the properties of neutron-rich nuclei, such as their masses, are required. These can be obtained with the JYFLTRAP Penning trap. Recently commissioned PI-ICR technique provides new opportunities for mass measurements of exotic nuclei at JYFLTRAP.

The properties of exotic nuclei and their reactions play also a key role in novae, type I x-ray bursts, and in the core collapse of supernovae. Our aim is to provide crucial and more reliable nuclear physics inputs for modeling these astronomical events and related nucleosynthesis. The experimental programme is mainly carried out at the IGISOL facility, and is complemented by experiments at other international radioactive ion beam facilities.

A. Kankainen et al., Physics Letters B 813, 136033 (2021). [Open Access: JYX]
Decay of the key 92-keV resonance in the 25Mg(p,γ) reaction to the ground and isomeric states of the cosmic γ-ray emitter 26Al
D.A. Nesterenko et al., Physics Letters B 808, 135642 (2020). [Open Access: JYX]
Three beta-decaying states in 128In and 130In resolved for the first time using Penning-trap techniques
L. Canete et al., Physical Review C 101, 041304(R) (2020). [Open Access: JYX]
Precision mass measurements of 67Fe and 69,70Co: Nuclear structure toward N = 40 and impact on r-process reaction rates
M. Vilén et al., Physical Review C 101, 034312 (2020). [Open Access:JYX]
Exploring the mass surface near the rare-earth abundance peak via precision mass measurements at JYFLTRA
A. Kankainen et al., Hyperfine Interactions 241, 43 (2020). [Open Access: JYX]
Recent experiments at the JYFLTRAP Penning trap
O. Kirsebom et al., Physical Review Letters 123, 262701 (2019). [Open Access: JYX]
Discovery of an Exceptionally Strong β-Decay Transition of ²⁰F and Implications for the Fate of Intermediate-Mass Stars. Editor's Suggestion with a Physics Viewpoint.
C.J. Horowitz et al., Journal of Physics G: Nuclear and Particle Physics 46, 083001 (2019). [Open Access: arXiv]
r-process nucleosynthesis : connecting rare-isotope beam facilities with the cosmos
D. Kahl et al., Physics Letters B 797, 134803 (2019). [Open Access]
Single-particle shell strengths near the doubly magic nucleus ⁵⁶Ni and the ⁵⁶Ni(p,γ)⁵⁷Cu reaction rate in explosive astrophysical burning
M. Vilen, A. Kankainen et al., Physical Review C 100, 054333 (2019). [Open Access: JYX]
High-precision mass measurements and production of neutron-deficient isotopes using heavy-ion beams at IGISOL
C.V. Hampton et al., Proceedings in Physics 219, 367-372 (2019). [Open Access: JYX or arXiv]
Women Scientists Who Made Nuclear Astrophysics
L. Canete, PhD thesis, University of Jyväskylä (2019).
High precision mass measurements for nuclear astrophysics
M. Vilen, PhD thesis, University of Jyväskylä (2019).
Mass measurements and production of ions at IGISOL for the astrophysical r- and rp-processes
M. Vilen, J. M. Kelly, A. Kankainen, M. Brodeur et al., Physical Review Letters 120, 262701 (2018). [Open Access: JYX]
Precision Mass Measurements on Neutron-Rich Rare-Earth Isotopes at JYFLTRAP: Reduced Neutron Pairing and Implications for r-Process Calculations
A. Kankainen, P.J. Woods et al., Physics Letters B 769, 549 (2017). [Open Access]
Measurement of key resonance states for the ³⁰P(p,γ)³¹S reaction rate, and the production of intermediate-mass elements in nova explosions
A. Kankainen, L. Canete et al., Physical Review C 93, 041304(R) (2016). [Open Access: JYX]
Mass of astrophysically relevant ³¹Cl and the breakdown of the isobaric multiplet mass equation

Weak interaction studies

Weak interaction is one of the four known fundamental interactions of nature. It is, for example, responsible for nuclear beta decay process, where proton is transformed to neutron or vice versa in the nucleus of an atom. At the same time also a positron and a neutrino (or electron and an anti-neutrino) is emitted. The energy released in the decay is distributed between the three particles -- each time in differently, underlying the challenges in studying beta decay.

The amount of energy released in the decay (also known as the Q-value) is one of the key quantities in these studies. Recently, through advances in atomic mass spectrometry, the most precise way of measuring a Q-value is through a mass difference measurement of the decay-parent and daughters. The energy is obtained using the mass-energy equivalence formula E=mc², where E is the decay energy, m the mass difference and c the speed of light.

A. de Roubin et al., Physical Review Letters 124, 222503 (2020).
[DOI: 10.1103/PhysRevLett.124.222503] [Open Access: JYX https://urn.fi/URN:NBN:fi:jyu-202006174245]
High-Precision Q-Value Measurement Confirms the Potential of 135Cs for Absolute Antineutrino Mass Scale Determination

Z. Ge et al., Physical Review Letters 127, 272301 (2021).
[DOI: 10.1103/PhysRevLett.127.272301] [Open Access: JYX https://urn.fi/URN:NBN:fi:jyu-202201241271]
159Dy Electron-Capture: A New Candidate for Neutrino Mass Determination

Z. Ge et al., Physical Review C 103, 065502 (2021).
[DOI: 10.1103/PhysRevC.103.065502] [Open Access: JYX https://urn.fi/URN:NBN:fi:jyu-202107084244]
Direct measurement of the mass difference of 72As-72Ge rules out 72As as a promising beta-decay candidate to determine the neutrino mass

Z. Ge et al., Physics Letters B 832, 137226 (2022).
[DOI: 10.1016/j.physletb.2022.137226] [Open Access: JYX https://urn.fi/URN:NBN:fi:jyu-202206293689]
High-precision electron-capture Q value measurement of 111In for electron-neutrino mass determination

T. Eronen et al., Physics Letters B 830, 137135 (2022).
[DOI: 10.1016/j.physletb.2022.137135] [Open Access: JYX https://urn.fi/URN:NBN:fi:jyu-202205112642]
High-precision measurement of a low Q value for allowed beta-decay of 131I related to neutrino mass determination

Z. Ge et al., Physical Review C 106, 015502 (2022).
[DOI: 10.1103/PhysRevC.106.015502] [Open Access: JYX https://urn.fi/URN:NBN:fi:jyu-202208254351]
Direct determination of the atomic mass difference of the pairs 76As-76Se and 155Tb-155Gd rules out 76As and 155Tb as possible candidates for electron (anti)neutrino mass measurements

D. A. Nesterenko et al., European Physical Journal A 58, 44 (2022).
[DOI: 10.1140/epja/s10050-022-00695-w] [Open Access: JYX https://urn.fi/URN:NBN:fi:jyu-202205252897]
High-precision Q-value measurement and nuclear matrix element calculations for the double-beta decay of 98Mo

Z. Ge et al., Physical Review C 108, 045502 (2023).
[DOI: 10.1103/PhysRevC.108.045502] [Open Access: JYX https://urn.fi/URN:NBN:fi:jyu-202310256646]
beta-decay Q-value measurement of 136Cs and its implications for neutrino studies

Z. Ge et al., Physics Letters B 859, 139094 (2024).
[DOI: 10.1016/j.physletb.2024.139094] [Open Access: https://urn.fi/URN:NBN:fi:jyu-202411137196]
High-precision measurements of the atomic mass and electron-capture decay Q value of 95Tc

Z. Ge et al., European Physical Journal A 60, 147 (2024).
[DOI: 10.1140/epja/s10050-024-01359-7] [Open Access: JYX https://urn.fi/URN:NBN:fi:jyu-202408015301]
High-precision measurement of the atomic mass of 84Sr and implications to isotope shift studies

Z. Ge et al., European Physical Journal A 60, 104 (2024).
[DOI: 10.1140/epja/s10050-024-01317-3] [Open Access: JYX https://urn.fi/URN:NBN:fi:jyu-202406044248]
Direct high-precision measurement of the mass difference of 77As–77Se related to neutrino mass determination

J. Ruotsalainen et al., Physical Review Letters 134, 172501 (2025).
[DOI: 10.1103/PhysRevLett.134.172501] [Open Access: JYX https://urn.fi/URN:NBN:fi:jyu-202504303701]
Ultralow Q_beta Value for the Allowed Decay of 110Ag^m Confirmed via Mass Measurements

J. Ruotsalainen et al., European Physical Journal A 61, 33 (2025).
[DOI: 10.1140/epja/s10050-024-01481-6] [Open Access: JYX https://urn.fi/URN:NBN:fi:jyu-202502182017]
Probing the double-beta decay of 104Ru through precise Q-value measurements and nuclear matrix element calculations

Z. Ge et al., Physical Review C 112, 035501 (2025).
[DOI: https://doi.org/10.1103/g393-xx1w] [Open Access: JYX https://urn.fi/URN:NBN:fi:jyu-202512089090]
High-precision direct decay energy measurements of the electron-capture decay of 97Tc

Enhancing Decay Spectroscopy with Purified Beams

In the realm of decay spectroscopy, the presence of radiation from contaminant isotopes with high production yields often poses a challenge. At IGISOL, we address this challenge through various purification methods. Initially, a 55-degree dipole magnet is employed for preliminary mass separation. Subsequently, the JYFLTRAP Penning trap, and soon the MR-TOF (Multi-Reflection Time-Of-Flight) mass spectrometer, are utilized to selectively isolate the desired isotope or even its specific isomeric state for in-depth decay studies.

Our research is fostered by collaborative efforts with international research groups. These partnerships provide invaluable support in terms of both manpower and resources. To leverage the ultra-pure beams available at IGISOL, we have deployed a range of advanced detection setups. Notable among these are the BELEN beta-delayed neutron detector, the Decay Total Absorption Spectrometer (DTAS), the TAsca Small Image mode Spectroscopy setup (TASISpec), and the beta-gamma coincidence setup (its HPGe detector array in a four-pack configuration is depicted in the accompanying photo). The latter comprises six germanium detectors, financed under the project "Multidetector Spectrometer of Low-Energy Gamma Photons" by J. Kurpeta, A. Płochocki, T. Rza̧ca-Urban, and W. Urban, and supported by the Polish Ministry of Science and Higher Education in 2013 (decision no. 6341/IA/115/2013). Furthermore, a new beta coincidence detector for the beta-gamma coincidence setup has been constructed with assistance from the National Centre for Nuclear Research in Poland.

Scientists from University of Jyväskyla, National Centre for Nuclear Research and University of Warsaw made an agreement to construct a beam line suitable to connect the MR-TOF facility to the beta-gamma spectroscopy setup. The beam line is under construction. When completed, the exotic nuclei of much shorter half-lives will be available to studies.

In a significant milestone, the Modular Neutron Spectrometer (MONSTER) designed for the FAIR facility was successfully commissioned with ⁸⁵As at IGISOL in March 2019, as detailed in our press release. The future holds promising prospects for MONSTER experiments at IGISOL.

Beta-gamma detector setup for post-trap spectroscopy at IGISOL.

V. Guadilla et al., Phys. Rev. Lett. 122, 042502 (2019). [Open Access: JYX] Large Impact of the Decay of Niobium Isomers on the Reactor Antineutrino Summation Calculations
V. Guadilla et al., Phys. Rev. C 100, 044305 (2019). [Open Access: JYX]
Total absorption γ-ray spectroscopy of the β-delayed neutron emitters ¹³⁷I and ⁹⁵Rb.
J. Kurpeta et al., Phys. Rev. C 100, 034316 (2019). [Open Access: JYX]
First β-decay scheme of ¹⁰⁷Nb : New insight into the low-energy levels of ¹⁰⁷Mo.
Ch. Lorenz et al., Phys. Rev. C 99, 044310 (2019). [Open Access: JYX]
β decay of ¹²⁷Cd and excited states in ¹²⁷In
J. Wisniewski et al., Phys. Rev. C 100, 054331 (2019). [Open Access: JYX]
Excited states in ⁸⁷Br populated in β decay of ⁸⁷Se

Fission studies

Charged particle induced fission has since 1980's utilised at IGISOL to produce neutron rich nuclei for spectroscopy. Since the ions extracted from the ion guide are primary fission products, and ions of any element can be extracted within tens of milliseconds, the technique is suitable for fission product yield distribution measurements, allowing studies of the fission process itself. Identification of the fission products on the basis of their mass with JYFLTRAP further enhances the FY measurements. In addition to charged particle induced fission, neutron induced fission can be studied utilising a recently build neutron converter.

V. Rakopoulos et al., Physical Review C 99, 014617 (2019). [Open Access: JYX].
Isomeric fission yield ratios for odd-mass Cd and In isotopes using the phase-imaging ion-cyclotron-resonance technique
A. Mattera et al. European Physical Journal A 54, 33 (2018). [Open Access: JYX].
Production of Sn and Sb isotopes in high-energy neutron-induced fission of ^natU
V. Rakopoulos et al., Physical Review C 98, 024612 (2018). [Open Access: JYX].
First isomeric yield ratio measurements by direct ion counting and implications for the angular momentum of the primary fission fragments
H. Penttilä, et al., Eur. Phys. J. A 48,43 (2012). [Open Access: link] Fission yield studies at the IGISOL facility
D. Gorelov, et al., Nuclear Instruments and Methods B 376, 46 - 51 (2016). [Open Access: JYX]
Developments for neutron-induced fission at IGISOL–4
A. Mattera, et al., Eur. Phys. J. A 53, 173. (2017). [Open Access: JYX]
A neutron source for IGISOL-JYFLTRAP: Design and characterisation

Optical spectroscopy

The structure and properties of atomic nuclei can be measured using many different techniques. One important class of techniques uses lasers to probe the energy levels of the electrons which are bound to the nucleus, in order to access the electromagnetic nuclear moments, the nuclear spin, and the changes in the size of the nucleus. These observables provide unique insight into the configuration of atomic nuclei, the purity of their wavefunctions, their shape and deformation and their nuclear sizes. Thus, they are exceptionally potent tests for nuclear models.

Optical spectroscopy techniques yield very precise values for these nuclear observables and can be applied even to short-lived isotopes produced with relatively low production rates. At the IGISOL laboratory, we currently have three experimental laser spectroscopy stations which offer a different compromise between experimental efficiency and resolution.

In addition to these spectroscopy experiments, we also house two experiments which rely on lasers to manipulate the properties of atoms or ions placed inside of traps. The aim of these projects is to look for physics beyond the standard model through precision beta-decay studies (MORA), and to realize the first experimental demonstration of gamma-ray coherent emission by means of super-radiance in a Bose-Einstein condensate of 135mCs isomers (GAMMALAS).

The collinear laser spectroscopy technique provides high resolution measurements of the nuclear size and electromagnetic moments. This method relies on the excitation of electrons of an isotope from the energy levels of a low-lying hyperfine manifold to those of an excited state using continuous wave lasers, followed by detection of the subsequent de-excitation. This is achieved by counting the fluorescence emitted by the atoms, using a photomultiplier tube. The energy difference between the hyperfine levels is sensitive to the nuclear properties and thus allows for their precise measurement. The high experimental resolution is achieved by performing the experiment in a collinear geometry, meaning that the ion beam and the laser beam are propagating along the same axis. Because the ion beam is accelerated to a high velocity (beam energy of 30 keV), Doppler broadening effects are thus suppressed.

The measured nuclear properties can be used to test our understanding of the nuclear many-body problem. As the nuclear magnetic moment probes the single particle nature of the nucleus while the quadrupole moment is related to the collective behavior, these properties combined provide crucial information about the complex interactions between the protons and neutrons inside the atomic nucleus. In addition to the electromagnetic moments, the changes in the nuclear charge radius of the radioactive isotopes with respect to the stable isotope can also be extracted from the laser spectroscopy measurements. This gives access to the variation of the nuclear charge distribution along an isotopic chain and provides information on both the bulk properties of nuclear matter and the details of nucleon-nucleon interactions.

Operating at the intersection of nuclear and atomic physics, this technique can also be used for the measurement of the atomic properties such as the hyperfine parameters or the atomic field and mass shift constants.

The RAPTOR project - RIS And Purification Traps for Optimised spectRoscopy

The RAPTOR project was initiated to provide a more efficient variant of collinear laser spectroscopy, though with a trade-off some in terms of the high precision of that method. The beamline is currently (2021) under commissioning; first results are expected in the coming months.

The RAPTOR beamline is designed to accept ion beams with a variable beam energy between 1 and 10 keV. This means that the Doppler broadening is suppressed less as compared to standard collinear laser spectroscopy, but gives the device a small footprint and provides longer interaction times between the atoms and the lasers. Rather than monitoring the excitation of the atoms via the detection of their spontaneous decay, instead a step-wise laser ionization process is used. Thus, more efficient charged-particle detection can be employed. The device is thus particularly well suited to the study of isotopes produced at very low rates and/or with very short lifetimes, but where the highest precision is not required to extract nuclear information.

The fact that atoms are laser ionized inside the RAPTOR beamline means they can then be further manipulated, for example to perform an additional purification. The lab has therefore also developed the capability of injecting ions from the RAPTOR beamline directly into the double-Penning trap mass spectrometer. Thus, ultra-low background hyperfine spectra can be obtained, free from any contribution of isobaric beam contamination.

The long interaction times offered by the use of slower beams also makes it possible to perform laser-radiofrequency double resonance spectroscopy, which offers superior precision on hyperfine constants of the atomic ground state, but provides no information on the excited atomic states. Thus, it is an ideal tool to measure higher-order nuclear moments or hyperfine anomalies, but is not sensitive to changes in the nuclear charge radius.

This project was funded by the Marie Skłodowska-Curie grant agreement No 844829.

IGISOL facility

The IGISOL (Ion Guide Isotope Separation On-Line) mass separator is the heart of the research infrastructure of the Exotic Nuclei and Beams -group. The facility is located in the newer part of the JYFL Accelerator Laboratory built around 10 years ago. IGISOL produces a broad range of low-energy (30 keV) radioactive and stable ion beams for studies of atomic nuclei and their properties.

Ion guides

The radioactive ions are produced with different kinds of techniques at the IGISOL (Ion Guide Isotope Separator On-Line) facility. We do active research and development work related to the ion guide method, gas cells and related production techniques.

The IGISOL method is fast, sub-ms technique for producing low-energy radioactive ion beams. It was developed in Jyväskylä in early 1980s. The IGISOL technique is chemically insensitive, and thus makes it possible to produce radioactive beams of all elements, including refractory elements usually difficult to produce at ISOL facilities. The basic idea, stopping of ions in gas with a swift extraction of radioactive ion beams, has been adopted in many major accelerator facilities worldwide over the years.

For example the following ion guides or ion sources have been used or developed at IGISOL:

Light-ion ion guide for fusion-evaporation reactions with p or d beams
Heavy-ion ion guide HIGISOL for heavy ion fusion-evaporation reactions
Fission ion guide for proton- or deuteron-induced fission
Fission ion guide designed for neutron-induced fission
Ion guide for multinucleon-transfer reactions
Hot cavity laser ion source
Off-line ion source station for stable ion beams

References to main publications describing the technique
The IGISOL technique—three decades of developments
Hyperfine Interactions 223, 17 (2014). [Open Access: link ]
I. D. Moore, P. Dendooven, J. Ärje
Production of neutron deficient rare isotope beams at IGISOL; on-line and off-line studies
Nuclear Instruments and Methods in Physics Research B 222 (2004) 632
J. Huikari et al.
Development and applications of the IGISOL technique
Nuclear Physics A 693 (2001) 477–494
J. Äystö
An inductively heated hot cavity catcher laser ion source
Review of Scientific Instruments 86, 123501 (2015)
M. Reponen et al.
Developments for neutron-induced fission at IGISOL-4
Nuclear Instruments and Methods in Physics Research B 376, 46 (2016).
[Open Access: JYX]
D. Gorelov et al.
Simulations of the fission-product stopping efficiency in IGISOL
European Physical Journal A 51, 59 (2015). [Open Access: JYX]
A. Al-Adili et al.
A new off-line ion source facility at IGISOL
Nuclear Instruments and Methods in Physics Research Section A 263, 382-383 (2020).
[Open Access: arXiv]
M. Vilen et al.

Radio-Frequency Quadrupole (RFQ) Cooler and Buncher

The RFQ cooler and buncher cools the ions and converts the continuous radioactive ion beam into narrow ion bunches. The ejected bunches are further used in different kinds of ion trapping and laser spectroscopy experiments. The RFQ cooler and buncher was developed and commissioned at IGISOL already in early 2000s. Details can be found from:

V. Virtanen et al., Nucl. Instrum. Meth. Phys. Res. A 1072 (2025) 170186
Miniaturised cooler-buncher for reduction of longitudinal emittance at IGISOL
A. Nieminen et al., Nucl. Instrum. Meth. Phys. Res. A 469 (2001) 244
Beam cooler for low-energy radioactive ions
A. Nieminen et al., Phys. Rev. Lett. 88 (2002) 094801
On-Line Ion Cooling and Bunching for Collinear Laser Spectroscopy

A new cooler-buncher for NUSTAR at FAIR has also been designed, constructed and commissioned at IGISOL:

A. Jaries et al., Nucl. Instrum. Meth. Phys. Res. A 1073 (2025) 170273
HIBISCUS: A new ion beam radio-frequency quadrupole cooler-buncher for high-precision experiments with exotic radioactive ions

JYFLTRAP Double Penning Trap Mass Spectrometer

JYFLTRAP is a cylindrical double Penning trap mass spectrometer at IGISOL. It is located inside a 7 T superconducting solenoid.

Details of the trap and used measurement methods can be found from:

JYFLTRAP: a Penning trap for precision mass spectroscopy and isobaric purification
T. Eronen et al., European Physical Journal A 48, 46 (2012). [Open Access: JYX].

Phase-Imaging Ion-Cyclotron-Resonance technique at the JYFLTRAP double Penning trap mass spectrometer
D.A. Nesterenko et al., European Physical Journal A 54, 154 (2018). [Open Access: JYX]

Study of radial motion phase advance during motion excitations in a Penning trap and accuracy of JYFLTRAP mass spectrometer
D.A. Nesterenko et al., European Physical Journal A 57, 302 (2021). Open Access.

Multi-Reflection Time-of-Flight Mass Spectrometer (MR-ToF-MS)

The Multi-Reflection Time-of-Flight Mass Spectrometer (MR-ToF-MS) at IGISOL consists of six electrode pairs that form a nearly energy-isochronous potential and a pulsed drift-tube, which traps the ions between the electrodes. With the MR-ToF-MS, mass-resolving powers of around 150 000 within 20 ms have been demonstrated. In addition to atomic mass measurements of short-lived exotic nuclides, the MR-ToF-MS can be used as a fast mass separator for various other experiments at IGISOL and as an ion counter for laser spectroscopy and yield measurements.

High-resolution multi-reflection time-of-flight mass spectrometer for exotic nuclei at IGISOL
V.A. Virtanen, T. Eronen, A. Kankainen, O. Beliuskina, Z. Ge, R.P. de Groote, A. Jokinen, M. Mougeot, A. de Roubin, J. Ruotsalainen, J. Sarén, and A. Takkinen
arXiv:2508.10048 [physics.ins-det]

Mass separation and atomic mass measurements of exotic radioactive nuclides with a multi-reflection time-of-flight mass spectrometer at the ion-guide isotope separator on-line facility
Ville Virtanen, PhD thesis, University of Jyväskylä (2025).
https://urn.fi/URN:ISBN:978-952-86-1036-6

Current

Projects

Members

Research group

Group leaders

Anu Kankainen

Academy Professor

Members

Staff scientist, Title of Docent

Juha Äystö

Professor, Emeritus

Zhuang Ge

Academy Research Fellow

Franziska Maier

Academy Research Fellow

Fedor Ivandikov

Postdoctoral Researcher

Simon Rausch

Postdoctoral Researcher

Vimal Vijayan

Postdoctoral Researcher

Natalia Ambrosio Macias

Doctoral Researcher

Luis Motilla Martinez

Doctoral Researcher

Prince Parvez

Doctoral Researcher

Wirunchana Rattanasakuldilok

External members

Saikumar Chinthakayala

Doctoral researcher

University of Jyväskylä & University of Caen

Ville Virtanen

Postdoctoral researcher

GANIL, Caen

Publications

No results.

Publications

Publication

2023

Studying Gamow-Teller transitions and the assignment of isomeric and ground states at N = 50

Physics Letters B.

Mollaebrahimi, Ali

Hornung, Christine

Dickel, Timo

Amanbayev, Daler

Kripko-Koncz, Gabriella

Plaß, Wolfgang R.

San Andrés, Samuel Ayet

Beck, Sönke

Blazhev, Andrey

Bergmann, Julian

Geissel, Hans

Górska, Magdalena

Grawe, Hubert

Greiner, Florian

Haettner, Emma

Kalantar-Nayestanaki, Nasser

Miskun, Ivan

Nowacki, Frédéric

Scheidenberger, Christoph

Bagchi, Soumya

Balabanski, Dimiter L.

Brencic, Ziga

Charviakova, Olga

Constantin, Paul

Dehghan, Masoumeh

Ebert, Jens

Gröf, Lizzy

Hall, Oscar

Harakeh, Muhsin N.

Kaur, Satbir

Kankainen, Anu

Knöbel, Ronja

Kostyleva, Daria, A.

Kurkova, Natalia

Kuzminchuk, Natalia

Mardor, Israel

Nichita, Dragos

Otto, Jan-Hendrik

Patyk, Zygmunt

Pietri, Stephane

Purushothaman, Sivaji

Reiter, Moritz Pascal

Rink, Ann-Kathrin

Roesch, Heidi

Spătaru, Anamaria

Stanic, Goran

State, Alexandru

Tanaka, Yoshiki K.

Vencelj, Matjaz

Weick, Helmut

Winfield, John S.

Yavor, Michael I.

Zhao, Jianwei

Publication

2023

The empirical shell gap revisited in light of recent high precision mass spectrometry data

European Physical Journal A.

Manea, Vladimir

Mougeot, Maxime

Lunney, David

Publication

2023

VADER : A novel decay station for actinide spectroscopy

Nuclear Instruments and Methods in Physics Research. Section B : Beam Interactions with Materials and Atoms.

Raggio, A.

Pohjalainen, I.

Rey-Herme, E.

Beliuskina, O.

Bequet, J.

Block, M.

Eronen, T.

Illana, A.

Jaries, A.

Kankainen, A.

Kumar, D.

Moore, I. D.

Mougeot, M.

Plaza, A. M.

Reponen, M.

Sarén, J.

Sulignano, B.

Stryjczyk, M.

Thisse, D.

Vandebrouck, M.

Warbinek, J.

Publication

2023

β-delayed neutron spectroscopy of 85,86As with MONSTER

European Nuclear Physics Conference. EPJ Web of Conferences. EDP Sciences.

Pérez de Rada, A.

Cano-Ott, D.

Martínez, T.

Alcayne, V.

Mendoza, E.

Plaza, J.

Sanchez-Caballero, A.

Villamarín, D.

Äystö, J.

Jokinen, A.

Kankainen, A.

Penttilä, H.

Rinta-Antila, S.

Agramunt, J.

Algora, A.

Domingo-Pardo, C.

Lerendegui-Marco, J.

Taín, J.L.

Banerjee, K.

Bhattacharya, C.

Roy, P.

Calviño, F.

Cortés, G.

Delafosse, C.

Matea, I.

Benito, J.

Alhomaidhi, S.

Mistry, A.K.

Publication

2023

β-delayed neutron spectroscopy of 85As with MONSTER

ND 2022. EPJ Web of Conferences.

Pérez de Rada, A.

Cano-Ott, D.

Martínez, T.

Alcayne, V.

Mendoza, E.

Plaza, J.

Sanchez-Caballero, A.

Villamarín, D.

Äystö, J.

Jokinen, A.

Kankainen, A.

Penttilä, H.

Rinta-Antila, S.

Agramunt, J.

Algora, A.

Domingo-Pardo, C.

Lerendegui-Marco, J.

Taín, J.L.

Banerjee, K.

Bhattacharya, C.

Roy, P.

Calviño, F.

Cortés, G.

Delafosse, C.

Matea, I.

Benito, J.

Alhomaidhi, S.

Mistry, A. K.

Publication

2023

β− decay Q-value measurement of 136Cs and its implications for neutrino studies

Physical Review C.

Ge, Z.

Eronen, T.

de Roubin, A.

Ramalho, M.

Kostensalo, J.

Kotila, J.

Suhonen, J.

Nesterenko, D. A.

Kankainen, A.

Ascher, P.

Beliuskina, O.

Flayol, M.

Gerbaux, M.

Grévy, S.

Hukkanen, M.

Husson, A.

Jaries, A.

Jokinen, A.

Moore, I. D.

Pirinen, P.

Romero, J.

Stryjczyk, M.

Virtanen, V.

Zadvornaya, A.

Publication

2022

Benchmark of a multi-physics Monte Carlo simulation of an ion guide for neutron-induced fission products

European Physical Journal A.

Gao, Z.

Al-Adili, A.

Cañete, L.

Eronen, T.

Gorelov, D.

Kankainen, A.

Lantz, M.

Mattera, A.

Moore, I. D.

Nesterenko, D. A.

Penttilä, H.

Pohjalainen, I.

Pomp, S.

Rakopoulos, V.

Rinta-Antila, S.

Vilén, M.

Äystö, J.

Solders, A.

Publication

2022

Coulomb excitation of 222Rn

Physical Review C.

Spagnoletti, P.

Butler, P. A.

Gaffney, L. P.

Abrahams, K.

Bowry, M.

Cederkäll, J.

Chupp, T.

de Angelis, G.

De Witte, H.

Garrett, P. E.

Goldkuhle, A.

Henrich, C.

Illana, A.

Johnston, K.

Joss, D. T.

Keatings, J. M.

Kelly, N. A.

Komorowska, M.

Konki, J.

Kröll, T.

Lozano, M.

Singh, B. S. Nara

O'Donnell, D.

Ojala, J.

Page, R. D.

Pedersen, L. G.

Raison, C.

Reiter, P.

Rodriguez, J. A.

Rosiak, D.

Rothe, S.

Scheck, M.

Seidlitz, M.

Shneidman, T. M.

Siebeck, B.

Sinclair, J.

Smith, J. F.

Stryjczyk, M.

Van Duppen, P.

Viñals, S.

Virtanen, V.

Wrzosek-Lipska, K.

Warr, N.

Zielińska, M.

Publication

2022

Design, construction and operation of the ProtoDUNE-SP Liquid Argon TPC

Journal of Instrumentation.

DUNE Collaboration

Publication

2022

Direct determination of the atomic mass difference of the pairs 76As−76Se and 155Tb−155Gd rules out 76As and 155 Tb as possible candidates for electron (anti)neutrino mass measurements

Physical Review C.

Ge, Z.

Eronen, T.

de Roubin, A.

Kostensalo, J.

Suhonen, J.

Nesterenko, D. A.

Beliuskina, O.

de Groote, R.

Delafosse, C.

Geldhof, S.

Gins, W.

Hukkanen, M.

Jokinen, A.

Kankainen, A.

Kotila, J.

Koszorús, Á.

Moore, I. D.

Raggio, A.

Rinta-Antila, S.

Virtanen, V.

Weaver, A. P.

Zadvornaya, A.

Publication

2022

Direct determination of the excitation energy of the quasistable isomer 180mTa

Physical Review C.

Nesterenko, D. A.

Blaum, K.

Delahaye, P.

Eliseev, S.

Eronen, T.

Filianin, P.

Ge, Z.

Hukkanen, M.

Kankainen, A.

Novikov, Yu. N.

Popov, A. V.

Raggio, A.

Stryjczyk, M.

Virtanen, V.

Publication

2022

First Offline Results from the S3 Low-Energy Branch

Atoms.

Romans, Jekabs

Ajayakumar, Anjali

Authier, Martial

Boumard, Frederic

Caceres, Lucia

Cam, Jean-François

Claessens, Arno

Damoy, Samuel

Delahaye, Pierre

Desrues, Philippe

Drouart, Antoine

Duchesne, Patricia

Ferrer, Rafael

Fléchard, Xavier

Franchoo, Serge

Gangnant, Patrice

de Groote, Ruben P.

Kraemer, Sandro

Lecesne, Nathalie

Leroy, Renan

Lory, Julien

Lutton, Franck

Manea, Vladimir

Merrer, Yvan

Moore, Iain

Ortiz-Cortes, Alejandro

Osmond, Benoit

Piot, Julien

Pochon, Olivier

Retailleau, Blaise-Maël

Savajols, Hervé

Sels, Simon

Traykov, Emil

Uusitalo, Juha

Vandamme, Christophe

Vandebrouck, Marine

Van den Bergh, Paul

Van Duppen, Piet

Verlinde, Matthias

Verstraelen, Elise

Wendt, Klaus

News

Open postdoctoral positions in the group!
- Postdoctoral Researcher in Experimental Nuclear Astrophysics (Deadline: 4th Feb 2026)
- Postdoctoral Researcher in Nuclear Astrophysics (Deadline: 4th Feb 2026)
- Postdoctoral Researcher in Experimental Nuclear Physics (Deadline: 4th Feb 2026)
- See also other positions open for the CoE in Neutron-Star Physics at https://neutronstars.fi/jobs/
Anu Kankainen appointed as Academy Professor (22.12.2025)
University of Jyväskylä part of breakthrough: Nuclear magnetism measured in a new way (9.12.2025)
Ion recycling opens the way to research into the heaviest elements (27.11.2025)
Centre of Excellence in Neutron-Star Physics funded by the Research Council of Finland (29.10.2025)
Dissertation: Development of measurement devices led to a breakthrough in the study of exotic nuclei (Virtanen 15.10.2025)
Dissertation: High-precision measurements made in the Accelerator Laboratory reveal the energies of nuclear decays (Ruotsalainen 10.10.2025)
Dissertation: New laser spectroscopy device strengthens nuclear physics research in Jyväskylä (Kujanpää 26.9.2025)
NUANZ project funded by the Research Council of Finland (16.6.2025)
Dissertation: Experimental insights from the mass measurement of neutron-rich rare-earth isotopes (Jaries 5.6.2025)
New silver mass brings us a step closer in our understanding of the antineutrino mass (6.5.2025)
Dissertation: Advancing laser and decay spectroscopy for actinide ion beam production (Raggio 28.3.2025)
A new feature discovered in radioactive lanthanum isotopes (31.1.2025)

Exotic nuclei and beams (IGISOL)

Research group description

Selected publications

Research

Nuclear Astrophysics

Weak interaction studies

Enhancing Decay Spectroscopy with Purified Beams

Fission studies

Optical spectroscopy

The RAPTOR project - RIS And Purification Traps for Optimised spectRoscopy

IGISOL facility

Ion guides

Radio-Frequency Quadrupole (RFQ) Cooler and Buncher

JYFLTRAP Double Penning Trap Mass Spectrometer

Multi-Reflection Time-of-Flight Mass Spectrometer (MR-ToF-MS)

ERC CoG Project MAIDEN

Heavy Exotic Nuclei for Nuclear Astrophysics

Mass measurements of exotic N=Z nuclei (up to 100Sn) and the vicinity for nuclear physics and nuclear astrophysics studies (MASSPASS)

From neutrino mass ordering to developing liquid scintillators for new applications

Research group

Group leaders

Members

External members

Saikumar Chinthakayala

Ville Virtanen

Publications

Publications

Studying Gamow-Teller transitions and the assignment of isomeric and ground states at N = 50

The empirical shell gap revisited in light of recent high precision mass spectrometry data

VADER : A novel decay station for actinide spectroscopy

β-delayed neutron spectroscopy of 85,86As with MONSTER

β-delayed neutron spectroscopy of 85As with MONSTER

β− decay Q-value measurement of 136Cs and its implications for neutrino studies

Benchmark of a multi-physics Monte Carlo simulation of an ion guide for neutron-induced fission products

Coulomb excitation of 222Rn

Design, construction and operation of the ProtoDUNE-SP Liquid Argon TPC

Direct determination of the atomic mass difference of the pairs 76As−76Se and 155Tb−155Gd rules out 76As and 155 Tb as possible candidates for electron (anti)neutrino mass measurements

Direct determination of the excitation energy of the quasistable isomer 180mTa

First Offline Results from the S3 Low-Energy Branch

News

Exotic nuclei and beams (IGISOL)

Research group description

Selected publications

Research

Nuclear Astrophysics

Selected publications

Weak interaction studies

Selected publications

Enhancing Decay Spectroscopy with Purified Beams

Selected publications

Fission studies

Selected publications

Optical spectroscopy

Collinear laser spectroscopy

IGISOL facility

Ion guides

Radio-Frequency Quadrupole (RFQ) Cooler and Buncher

JYFLTRAP Double Penning Trap Mass Spectrometer

Multi-Reflection Time-of-Flight Mass Spectrometer (MR-ToF-MS)

Related projects

ERC CoG Project MAIDEN

Heavy Exotic Nuclei for Nuclear Astrophysics

Mass measurements of exotic N=Z nuclei (up to 100Sn) and the vicinity for nuclear physics and nuclear astrophysics studies (MASSPASS)

From neutrino mass ordering to developing liquid scintillators for new applications

Research group

Group leaders

Members

External members

Saikumar Chinthakayala

Ville Virtanen

Publications

Publications

News