In the last decades ISOL
(Isotope separation On-Line) facilities working online with different types of particle accelerators became a powerful tool for the nuclear structure studies and astrophysics.
ISOL facilities working online with high intensity proton beams accelerated to ?1 GeV energy are very effective for production of intense beams of radioactive isotopes of large variety of elements. Word leaders in this field are the ISOLDE
(CERN) and ISAC
In Russia the first ISOL installation, named IRIS
(Investigation of Radioactive Isotopes on Synchrocyclotron), was built at Petersburg Nuclear Physics Institute (PNPI) in Gatchina in 1975 under the leadership of Prof. E.Ye.Berlovich
. For a long time it was the only working ISOL facility in Russia and former-USSR states. From 1964 to 1977, E.Ye.Berlovich was head of the Short-Lived Nuclei Laboratory, which is based on the IRIS facility. Later the laboratory heads were G.D. Alkhazov (1978-1992) and D.M. Seliverstov (1993-2002). Since 2003 the Short-Lived Nuclei Laboratory is headed by V.N. Panteleev.
Initially the main goal of the laboratory was the investigation of the short-lived nuclides far away from the beta-stability line using various nuclear spectroscopy techniques. IRIS facility was put into operation in December 1975 on the 1 GeV proton beam of the PNPI synchrocyclotron, soon after that a first series of experiments on exotic nuclei were performed: finding new isotopes, atomic mass measurements, and therefore identification of a proton drip line. In 1980 the laboratory started a large scale program of beta-decay strength function measurements for neutron-deficient isotopes in the rear-earth region using a total absorption gamma-ray spectrometer. In 1983 in collaboration with the Institute of Spectroscopy (headed by V.S. Letokhov
) the first experimental data on atomic hyperfine structure and isotope shifts for neutron-deficient nuclides were obtained using a laser setup, which was built at IRIS facility. In this studies the new technique of resonance photoionization laser spectroscopy was pioneered. Due to its high sensitivity this method allowed for experiments with a large number of short-lived isotopes which were previously unavailable for laser spectroscopy.
In 1988 V.N. Panteleev, G.D. Alkhazov, and E.Ye.Berlovich proposed a new conception of a laser ion source with a hot metal cavity ionizer new conception of a laser ion source with a hot metal cavity ionizer. In 1991 the first experiment were carried out: beta-decay strength function for 152
Ho was measured. At laser ion sources of this type are in use at world leading ISOL facilities (ISOLDE, TRIUMF, GANIL). The main advantage of laser ion source besides its high efficiency is isobaric (and in some cases, isomeric) selectivity due to resonance character of photoionization.
The resonance ionization laser ion source is used at IRIS not only for ionizing the reaction products to produce an ion beam of exotic nuclides, but it was adapted to become a powerful tool for performing laser spectroscopy measurements to study of nuclear properties such as spins, electromagnetic moments and charge radii of ground- and isomeric states along an isotope chain (Yb, Tm, Tl. Bi etc.).
In mid 2000s a large scale program for studies of the nuclei in the Pb region using the in-source laser spectroscopy was started in collaboration with ISOLDE
(CERN). This program combines the opportunities provided by both facilities. In this experiments the physicists from the Short-Lived Nuclei Laboratory are playing a key role. Within this collaboration a data for more than 100 nuclei was obtained, new and very interesting effects were found, which significantly changing views on nuclear shape evolution and coexistence. The main results were published in Nature, Nature Physics, and Physical Review Letters
A target –ion source unit is a key element of any ISOL system, that is why a number of new original ion source-target systems was developed, which allowed to produce and to investigate both neutron-deficient and neutron-rich nuclei. In this field the Short-lived Nuclei collaborates successfully with well-known laboratories as ISOLDE
The target –ion source development is of great importance for an implementation of mass-separators for producing radioactive isotopes for medical applications (diagnostics and therapy of malignant tumors). A participation in the development of a radioisotope facility based on the C-80 cyclotron
is a part of a Medical program of the Short-Lived Nuclei Laboratory.
The IRIS development is still underway: recently a new universal laser spectroscopic facility (ULISS) was built for an investigation of new regions of exotic nuclei.
In At Short-Lived Nuclei Laboratory a new ISOL project was started recently: a new facility IRINA
(Investigation of Radioactve Isotopes using Neutrons) is planned to be constructed at high-flux nuclear reactor PIK. The main goal of this facility is a production and investigation of intense beams of neutron rich isotopes produced by in-target fission of 235
U induced by thermal neutrons.
At present, mass-separator complex IRINA is under design. Recently, the technical proposals for all main parts of IRINA (target-ion source system, mass-separator with ion guides, laser installation and the special hot cell) have been prepared and discussed with the possible manufactures.
For more information see “Main directions of HEPD PNPI scientific activity” section:
Studies of nuclei far from beta-stability at the IRIS facility
The RIC-80 project (Radioactive Isotopes at the C-80 Cyclotron )
The IRINA (Investigation of Radioactive Isotopes with Neutrons) project