Current activities of LPEN
Since the middle of the previous decade a group of LPEN focused on research in foreign centers in works with the ion Penning traps. The ion trap is a highly sensitive and high-precision device that has broadly multifunctional applications in fundamental and applied research. It has no equal in mass spectrometry on these parameters (see K. Blaum, Yu.N. Novikov and G. Werth
, Contemporary Physics 51
To date LPEN actively participates in many existing European projects with the ion Penning traps: ISOLTRAP (ISOLDE, CERN), SHIPTRAP (GSI, Darmstadt), JYFLTRAP (Jyvaskyla) and TRIGATRAP (Mainz). The main activity of the LPEN is the study of exotic nuclei and exotic physical phenomena using ion traps.
Physical tasks, on which a staff of the LPEN works
The development of new projects where the LPEN is involved
- The definition of mass landscape of nuclides of superheavy elements
Direct mass measurements of isotopes of elements No and Lr at the setup SHIPTRAP initiated determination of the mass surface of the region of superheavy nuclides (see M. Block et al., Nature 463 (2010) 785; and E. Minaya Ramirez, et al. Science 337 (2012) 1207). These pioneer works made by German scientists in collaboration with LPEN, and which do not have analogues in the world practice, were awarded the 2013 international G. Flerov prize. The collaboration is going to continue the research in the future.
- The search for the new candidates for the measurement of the neutrino mass in the process of electron capture by the nucleus
Studies were initiated at the setup ISOLTRAP/ISOLDE at CERN (see S. Eliseev et al., Phys. Lett. B 693 (2010) 426). 194Hg was determined as one of the possible candidates. The research program continues on the project IS-473/ISOLDE.
- The search for the candidates for the neutrinoless double electron capture by the nucleus
The large-scale systematic measurements of the mass difference between stable nuclides have been performed to identify the nuclide pairs with energetically degenerate states, which can be related with neutrinoless transition (see S. Eliseev, Yu. Novikov, and K. Blaum, J. Phys. G 39 (2012) 124003). The presence of such process would indicate a violation of the lepton number conservation law and Majorana-type of neutrinos. 152Gd was found as the most likely candidate for the study of the resonance effect. Possibility of multiple resonance in 154Dy was observed for the first time. The work is performed at the setup SHIPTRAP with the cooperation of German scientists with LPEN and St. Petersburg State University. (S. Eliseev, Yu.N. Novikov, K. Blaum, Ann. der Phys. 525 (2013) 707).
- Study of possibility of using of an orbital electron capture by the nuclei to identify the relic neutrinos and heavy sterile neutrinos
Estimation and analysis of the data show that the nuclide 157Tb can be used to identify the presence of the relic neutrinos in the process of resonance capture (J. Vergados and Yu.N. Novikov, J. Phys. G 41 (2014) 125001). Work of LPEN with foreign colleagues also show that a set of nuclides can be used as a test in the terrestrial laboratory conditions to identify sterile neutrinos in the mass range 1-100 keV (P. Filianin, K. Blaum et al., J. Phys. G 41 (2014) 095089). It is believed that they are candidates for warm dark matter in the universe. The project provides for the study of experimental possibilities with the use of ion traps in combination with a cryogenic microcalorimetry.
- Measurements of mass difference of nuclides for the purposes of cosmochronology
This project, carried out jointly with Max Planck Institute for Physics and group of SHIPTRAP at GSI, was initiated with a measurement of the mass difference between 187Re-187Os, in which the parent nucleus 187Re can be used to determine the age of the Universe due to its very long lifetime. However, the probability of the reverse process from thermally populated excited states of 187Os, which can greatly disrupt the balance of natural abundance of Re/Os, depends on the accuracy and reliability of measurements of the mass difference in this pair (D. Nesterenko, S. Eliseev et al., Phys. Rev. 90 (2014) 042501). In these measurements we used a new method for the determination of the cyclotron frequency of ions that rotate in a magnetic field based on the phase analysis of their motion in the Penning trap. This method, recently developed, allows to increase the accuracy of mass determination and resolving power (S. Eliseev et al., Phys. Rev. Lett. 110 (2013), 082501).
A similar picture can be observed for other pairs of nuclides, which are interested for astrophysics, the mass of which is to be measured.
- Precision measurements of the smallest of the existing end-point energies of beta-transformations
The project aims to precision measurements of the mass difference between ground states of the mother nuclei and excited states of the daughter nuclei with the expected lowest energies of beta-transitions known in the literature. The analysis selected nuclides, which are proposed to measure at first. The reasons are the possibility of using these nuclides for alternative measurements of neutrino mass, as well as verification of the theory of beta-decay at very low energies (lower than 1 keV). Similar complementary projects have been approved by the Program Committees JYFLTRAP (Finland) and ISOLDE (CERN) with the allocation of beam time in the respective centers (coordinator is S.A. Eliseev).
- Ultra-precision mass measurements. Project ECHo, devoted to the determination of the neutrino mass in the process of electron capture by nucleus 163Ho
The experimental part of the project ECHo consists of two complementary sub-projects: ultra-precision measurement of the mass difference between 163Ho-163Dy in the trap PENTATRAP and calorimetric measurements of the atomic spectrum of the de-excitation after the capture of an orbital electron by the nucleus. LPEN participates in the development and implementation of the setup of five-traps tandem PENTATRAP, which is being realized with German colleagues at Max Planck Institute for Physics in Heidelberg (J. Repp et al., App. Phys. B 107 (2012) 983; C. Roux et al., App. Phys. B 107 (2012) 995). The expected relative accuracy of mass determination will constitute the record value of 10–11.
- The MATS project of the future FAIR facility in Darmstadt (Germany)
LPEN is a participant of the project MATS aimed at mass measurements of high-charged ions in a trap (Yu.N. Novikov et al., Atomic Energy 112 (2012) 117). Area of responsibility includes the creation of a mass calibrator and silicon detectors with a thin entrance window.
- Decay study of isomeric state 229Thm as possible frequency standard.
The detection of isomeric state of 229Th with the energy 7.6 eV outlines intriguing opportunities in technology and fundamental science. Small energy condition gives hope to use the laser methods for control of nuclear transition and opens the way for the development more accurate and possibly more compact (solid state) standard of frequency.
The preparatory work aiming at the identification of the isomer in 229Th through a measurement of its hyperfine structure was done by IGISOL team (JYFL) with involvement of LPEN. The possibility to make alternative study in PNPI is currently under consideration.
- The project of Penning trap PITRAP for studies of nuclides produced at the reactor PIK.
(see Booklet )
LPEN, having a great experience with ion traps abroad, is going to create the first Russian Penning trap for precision mass measurements (Yu.I. Gusev et al., Preprint PNPI-2960 (2014)). According to the project the Penning trap can be used in the “on-line” mode on the beam of the products of the neutron fission from the reactor, as well as in the “off-line” mode using stable or long-lived nuclides produced at the reactor. The ion-optical system adjusted to two possibilities of transporting the ion beam to the tandem of two Penning traps (preparation and measurement trap): to the gas jet system as well as to the electromagnetic mass separator.
The setup PITRAP, placed in the experimental hall of the PIK reactor, will combine the advantages of using a high flux of neutrons with high sensitivity (at the level of single particles) of the trap. The expected high yields of exotic nuclides will achieve nuclide way of the astrophysical process of rapid capture of neutrons occurring in Supernovae (r-process). Determination of the true path of this process in a terrestrial laboratory can be carried out only as a result of mass measurement (total binding energy) of nuclides in the assumed region of the r-process that will be carried out by a Penning trap.
The project uses the development of setup TRIGATRAP with the Penning trap installed at the TRIGA reactor in Mainz (Germany), setup SHIPTRAP with the Penning trap, placed after the mass separator of heavy ions SHIP in Darmstadt (Germany), and setup ISOLTRAP with the Penning trap, placed after the mass separator ISOLDE (CERN). LPEN supports a fruitful cooperation with these groups for many years.