PNPI Group Leader:    V.N. Panteleev

       IRIS (Investigation of Radioactive Isotopes on Synchrocyclotron) is the first in Russia ISOL (Isotope Separator On-Line) facility in Russia for an investigation of nuclei far from stability. The first experiments at IRIS were performed in 1975. The main part of the IRIS facility is a mass separator working online with the 1 GeV proton beam from PNPI synchrocyclotron. The neutron-reach and neutron-deficient nuclei are produced in nuclear reactions induced by 1 GeV protons impinging on a massive target. The nuclear reaction products diffuse out of the high temperature target and effuse as neutral atoms into a cavity of the ion source. After ionization, acceleration to 30 keV and mass separation, the ions are implanted in one of the detection systems available. The obtained radioactive samples are investigated using alpha-, beta-, gamma- detectors, or with other types of registration.
       Method of resonance photoionization spectroscopy proved to be highly efficient for the investigations of nuclei far off stability. This technique was pioneered at the IRIS facility for the studies of ground and isomeric states of exotic nuclei. Later a new conception of this method was developed at IRIS: the in-source resonance photoionization spectroscopy. Application of the laser spectroscopy at IRIS allowed for the charge radii and electromagnetic moment measurements for more than 100 neutron-deficient nuclei in the rare-earth region.
       Masses of more than 100 radioactive nuclides were determined using measured at the IRIS facility beta-decay energies. The performed measurements of the beta-decay strength functions allowed for the experimental demonstration of their resonance nature for the first time.
       The main fields of the scientific activity at Short-Lived Nuclei Laboratory are listed here:

• Studies of spins, electromagnetic moments, and charge radii of radioactive nuclei using laser spectroscopy after mass-separation;  (See also publications-1.pdf)
  
  
• Search for new short-lived isotopes far from stability;
  
  
• Identification of the drip line of the proton unstable nuclides;
  
  
• Measurements of beta-decay energy and mass determination for short-lived isotopes;
  
  
• Search for delayed fission of neutron-reach nuclei;
  
  
• In-source laser resonance photoionization spectroscopy on neutron-deficient nuclei in the rare-earth region using high-temperature target;   (See also publications-2.pdf)
  
  
• Studies of ground- and isomeric states properties of heavy element in the Pb-region by in-source photoionization laser spectroscopy combined with synchronous nuclear decay spectroscopy at the ISOLDE facility;  (See also publications-3.pdf)
  
  
• Development of high-temperature targets and ion sources for production of intense beams of radioactive nuclides far from stability;
  
  
• Development of the universal laser-spectroscopic system (ULISS) for selective production and laser spectroscopy studies of neutron-deficient and neutron rich nuclei far from stability.