Exotic nuclei and beams (IGISOL)

The exotic nuclei and beams group studies properties of nuclei employing Penning-trap mass spectrometry as well as 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.

Research group type

Research group

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

Our research takes place in number of other laboratories, such as the facility in , and , the location of the future radioactive beam facility . We are actively involved in work to support the development of international future facilities and , in close collaboration with , the Helsinki Institute of Physics.

An important form of our international collaboration is also participation in research networks. Recently, our group has benefited from the EU FP7 and Horizon 2020 programs within ENSAR2, CHANDA and nuClock projects. Two new EU EURATOM projects SANDA and ARIEL started in 2019. Our research is also strongly supported by the Academy of Finland.

No results.

Selected publications

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).

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)

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.

. [Open Access: ]
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
. [Open Access: ]
Three beta-decaying states in 128In and 130In resolved for the first time using Penning-trap techniques
. [Open Access: ]
Precision mass measurements of 67Fe and 69,70Co: Nuclear structure toward N = 40 and impact on r-process reaction rates
. [Open Access:]
Exploring the mass surface near the rare-earth abundance peak via precision mass measurements at JYFLTRA
. [Open Access: ]
Recent experiments at the JYFLTRAP Penning trap
[Open Access: ]
Discovery of an Exceptionally Strong β-Decay Transition of ²⁰F and Implications for the Fate of Intermediate-Mass Stars. Editor's Suggestion with a .
[Open Access: ]
r-process nucleosynthesis : connecting rare-isotope beam facilities with the cosmos
[Open Access]
Single-particle shell strengths near the doubly magic nucleus ⁵⁶Ni and the ⁵⁶��(��,γ)⁵⁷Cu reaction rate in explosive astrophysical burning
[Open Access: ]
High-precision mass measurements and production of neutron-deficient isotopes using heavy-ion beams at IGISOL
[Open Access: or ]
Women Scientists Who Made Nuclear Astrophysics
High precision mass measurements for nuclear astrophysics
Mass measurements and production of ions at IGISOL for the astrophysical r- and rp-processes
[Open Access: ]
Precision Mass Measurements on Neutron-Rich Rare-Earth Isotopes at JYFLTRAP: Reduced Neutron Pairing and Implications for r-Process Calculations
[Open Access]
Measurement of key resonance states for the ³⁰��(��,γ)³¹S reaction rate, and the production of intermediate-mass elements in nova explosions
[Open Access: ]
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.

Decay spectroscopy with purified beams

ecay spectroscopy studies are often hampered by contaminant radioactive decays from isotopes with high production rates. At IGISOL, radioactive ion beams can be purified in several ways. The 55 degree dipole magnet is used for a rough mass separation. The JYFLTRAP Penning trap, and in future the MR-TOF multi-reflection time-of-flight mass spectrometer, can be used to select the isotope or even the isomeric state of interest for decay spectroscopy studies.

The research is done in collaboration with international research groups. Several detector arrays have utilized the ultra-pure beams provided by the facility, such as BELEN beta-delayed neutron detector, DTAS total absorption spectrometer, the TASISpec detector setup, and the University of Warsaw Ge-detector array (shown in the photo). The six germanium detectors making the base of the Ge-detector array were financed within the project ”Multidetector spectrometer of low-energy gamma photons” prepared by J. Kurpeta, A. Płochocki, T. Rza̧ca-Urban and W. Urban, granted by the Polish Ministry of Science and Higher Education in 2013 (decision no. 6341/IA/115/2013).

In 2019, the MONSTER (Modular Neutron Spectrometer) designed for the FAIR facility was successfully commissioned with 85As at IGISOL in March 2019, see the press release. Prospects for future MONSTER experiments at IGISOL look bright.

[Open Access: ] Large Impact of the Decay of Niobium Isomers on the Reactor Antineutrino Summation Calculations
[Open Access: ]
Total absorption γ-ray spectroscopy of the β-delayed neutron emitters ¹³⁷I and ⁹⁵Rb.
[Open Access: ]
First β-decay scheme of ¹⁰⁷Nb : New insight into the low-energy levels of ¹⁰⁷Mo.
[Open Access: ]
β decay of ¹²⁷Cd and excited states in ¹²⁷In
[Open Access: ]
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.

[Open Access: ].
Isomeric fission yield ratios for odd-mass Cd and In isotopes using the phase-imaging ion-cyclotron-resonance technique
[Open Access: ].
Production of Sn and Sb isotopes in high-energy neutron-induced fission of ^natU
[Open Access: ].
First isomeric yield ratio measurements by direct ion counting and implications for the angular momentum of the primary fission fragments
[Open Access: ] Fission yield studies at the IGISOL facility
. [Open Access: ]
Developments for neutron-induced fission at IGISOL–4
[Open Access: ]
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 -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
Hyperfine Interactions 223, 17 (2014). [Open Access: ]
I. D. Moore, P. Dendooven, J. Ärje
Nuclear Instruments and Methods in Physics Research B 222 (2004) 632
J. Huikari et al.
Nuclear Physics A 693 (2001) 477–494
J. Äystö
Review of Scientific Instruments 86, 123501 (2015)
M. Reponen et al.
Nuclear Instruments and Methods in Physics Research B 376, 46 (2016).
[Open Access: ]
D. Gorelov et al.
European Physical Journal A 51, 59 (2015). [Open Access: ]
A. Al-Adili et al.
Nuclear Instruments and Methods in Physics Research Section A 263, 382-383 (2020).
[Open Access: ]
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
A. Nieminen et al., Nucl. Instrum. Meth. Phys. Res. A 469 (2001) 244
A. Nieminen et al., Phys. Rev. Lett. 88 (2002) 094801

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

A. Jaries et al., Nucl. Instrum. Meth. Phys. Res. A 1073 (2025) 170273

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:

T. Eronen et al., European Physical Journal A 48, 46 (2012). [Open Access: ].

D.A. Nesterenko et al., European Physical Journal A 54, 154 (2018). [Open Access: ]

D.A. Nesterenko et al., European Physical Journal A 57, 302 (2021). Open Access.

Publications

Publication

2021

Physical Review Letters

Barzakh, A.

Andreyev, A. N.

Raison, C.

Cubiss, J. G.

Van Duppen, P.

Péru, S.

Hilaire, S.

Goriely, S.

Andel, B.

Antalic, S.

Al Monthery, M.

Berengut, J. C.

Bieroń, J.

Bissell, M. L.

Borschevsky, A.

Chrysalidis, K.

Cocolios, T. E.

Day Goodacre, T.

Dognon, J.-P.

Elantkowska, M.

Eliav, E.

Farooq-Smith, G. J.

Fedorov, D. V.

Fedosseev, V. N.

Gaffney, L. P.

Garcia Ruiz, R. F.

Godefroid, M.

Granados, C.

Harding, R. D.

Heinke, R.

Huyse, M.

Karls, J.

Larmonier, P.

Li, J. G.

Lynch, K. M.

Maison, D. E.

Marsh, B. A.

Molkanov, P.

Mosat, P.

Oleynichenko, A. V.

Panteleev, V.

Pyykkö, P.

Reitsma, M. L.

Rezynkina, K.

Rossel, R. E.

Rothe, S.

Ruczkowski, J.

Schiffmann, S.

Seiffert, C.

Seliverstov, M. D.

Sels, S.

Skripnikov, L. V.

Stryjczyk, Marek

Studer, D.

Verlinde, M.

Wilman, S.

Zaitsevskii, A. V.

Publication

2021

Physical Review A

de Groote, R. P.

Kujanpää, S.

Koszorús, Á.

Li, J. G.

Moore, I. D.

Publication

2021

Physical Review C

Mardor, I.

Ayet San Andrés, S.

Dickel, T.

Amanbayev, D.

Beck, S.

Bergmann, J.

Geissel, H.

Gröf, L.

Haettner, E.

Hornung, C.

Kalantar-Nayestanaki, N.

Kripko-Koncz, G.

Miskun, I.

Mollaebrahimi, A.

Plaß, W. R.

Scheidenberger, C.

Weick, H.

Bagchi, Soumya

Balabanski, D. L.

Bezbakh, A. A.

Brencic, Z.

Charviakova, O.

Chudoba, V.

Constantin, Paul

Dehghan, M.

Fomichev, A. S.

Grigorenko, L. V.

Hall, O.

Harakeh, M. N.

Hucka, J.-P.

Kankainen, A.

Kiselev, O.

Knöbel, R.

Kostyleva, D. A.

Krupko, S. A.

Kurkova, N.

Kuzminchuk, N.

Mukha, I.

Muzalevskii, I. A.

Nichita, D.

Nociforo, C.

Patyk, Z.

Pfützner, M.

Pietri, S.

Purushothaman, S.

Reiter, M. P.

Roesch, H.

Schirru, F.

Sharov, P. G.

Spătaru, A.

Stanic, G.

State, A.

Tanaka, Y. K.

Vencelj, M.

Yavor, M. I.

Zhao, J.

Publication

2021

Physical Review C

Canete, L.

Lotay, G.

Christian, G.

Doherty, D. T.

Catford, W. N.

Hallam, S.

Seweryniak, D.

Albers, H. M.

Almaraz-Calderon, S.

Bennett, E. A.

Carpenter, M. P.

Chiara, C. J.

Greene, J. P.

Hoffman, C. R.

Janssens, R. V. F.

José, J.

Kankainen, A.

Lauritsen, T.

Matta, A.

Moukaddam, M.

Ota, S.

Saastamoinen, A.

Wilkinson, R.

Zhu, S.

Publication

2021

Physical Review C

Andel, B.

Van Duppen, P.

Andreyev, A. N.

Blazhev, A.

Grawe, H.

Lică, R.

Naïdja, H.

Stryjczyk, Marek

Algora, A.

Antalic, S.

Barzakh, A.

Benito, J.

Benzoni, G.

Berry, T.

Borge, M. J. G.

Chrysalidis, K.

Clisu, C.

Costache, C.

Cubiss, J. G.

De Witte, H.

Fedorov, D. V.

Fedosseev, V. N.

Fraile, L. M.

Fynbo, H. O. U.

Greenlees, Paul T.

Harkness-Brennan, L. J.

Huyse, M.

Illana, A.

Jolie, J.

Judson, D. S.

Konki, Joonas

Lazarus, I.

Madurga, M.

Marginean, N.

Marginean, R.

Mihai, C.

Marsh, B. A.

Molkanov, P.

Mosat, P.

Murias, J. R.

Nacher, E.

Negret, A.

Page, R. D.

Pascu, S.

Perea, A.

Pucknell, V.

Rahkila, Panu

Rapisarda, E.

Rezynkina, K.

Sánchez-Tembleque, V.

Schomacker, K.

Seliverstov, M. D.

Sotty, C.

Stan, L.

Sürder, C.

Tengblad, O.

Vedia, V.

Viñals, S.

Wadsworth, R.

Warr, N.

Publication

2021

Nuclear Instruments and Methods in Physics Research Section A: Accelerators Spectrometers Detectors and Associated Equipment

Daya Bay collaboration

JUNO collaboration

Publication

2021

Ojala, Jari

Äystö, Juha

Publication

2021

Journal of Instrumentation

WA105 collaboration

Publication

2021

International Symposium on Negative Ions, Beams and Sources

Tarvainen, Olli

Kronholm, Risto

Laitinen, Mikko

Reponen, Mikael

Julin ,Jaakko

Toivanen, Ville

Napari, Mari

Marttinen, Miha

Kalvas, Taneli

Faircloth, Dan

Koivisto, Hannu

Sajavaara, Timo

Publication

2021

European Physical Journal C

DUNE Collaboration

Publication

2021

Physics Letters B

Koszorús, Á.

Vormawah, L.J.

Beerwerth, R.

Bissell, M.L.

Campbell, P.

Cheal, B.

Devlin, C.S.

Eronen, T.

Fritzsche, S.

Geldhof, S.

Heylen, H.

Holt, J.D.

Jokinen, A.

Kelly, S.

Moore, I.D.

Miyagi, T.

Rinta-Antila, S.

Voss, A.

Wraith, C.

Publication

2021

Frontiers in Oncology

Boscolo, Daria

Kostyleva, Daria

Safari, Mohammad Javad

Anagnostatou, Vasiliki

Äystö, Juha

Bagchi, Soumya

Binder, Tim

Dedes, Georgios

Dendooven, Peter

Dickel, Timo

Drozd, Vasyl

Franczack, Bernhard

Geissel, Hans

Gianoli, Chiara

Graeff, Christian

Grahn, Tuomas

Greiner, Florian

Haettner, Emma

Haghani, Roghieh

Harakeh, Muhsin N.

Horst, Felix

Hornung, Christine

Hucka, Jan-Paul

Kalantar-Nayestanaki, Nasser

Kazantseva, Erika

Kindler, Birgit

Knöbel, Ronja

Kuzminchuk-Feuerstein, Natalia

Lommel, Bettina

Mukha, Ivan

Nociforo, Chiara

Ishikawa, Shunki

Lovatti, Giulio

Nitta, Munetaka

Ozoemelam, Ikechi

Pietri, Stephane

Plaß, Wolfgang R.

Prochazka, Andrej

Purushothaman, Sivaji

Reidel, Claire-Anne

Roesch, Heidi

Schirru, Fabio

Schuy, Christoph

Sokol, Olga

Steinsberger, Timo

Tanaka, Yoshiki K.

Tanihata, Isao

Thirolf, Peter

Tinganelli, Walter

Voss, Bernd

Weber, Uli

Weick, Helmut

Winfield, John S.

Winkler, Martin

Zhao, Jianwei

Scheidenberger, Christoph

Parodi, Katia

Durante, Marco

Super-FRS Experiment Collaboration

Research group

Group leaders

Ari Jokinen

Professor

Members

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