21.03.2019

Nuclear and Accelerator-Based Physics Seminars

Suggestions for speakers are most welcome! Contact Tuomas Grahn or Anu Kankainen.

Upcoming Seminars

  • March 22, 2019 at 14:15 in FYS3. Pierre Chauveau (CSNSM Orsay)
    PILGRIM and MLLTRAP: opportunities with ion-traps at the low energy beam lines of S3, DESIR and ALTO
    PILGRIM and MLLTRAP will be respectively the first MR-ToF-MS and the first Penning trap operating in France. PILGRIM, will be part of S3-LEB and will be used to purify the beam from isobaric contaminants and for mass measurement with uncertainties down to a few 10^-7. MLLTRAP is currently installed at ALTO and will ultimately be moved to DESIR. Two alternate double trap assemblies can be inserted in MLLTRAP’s 7T magnet. The first is dedicated to high-precision mass measurement with a proven 3X10^-8 uncertainty. The second is dedicated to in-trap decay spectroscopy and nuclear level lifetime measurement of heavy to superheavy alpha emitters. This seminar will review the development, tests and expected perfomances of these traps, as well as the physics opportunities they open at S3 and ALTO, and later in DESIR.

Past Seminars

  • March 14, 2019 at 15:15 in FYS3, Daniel Cano Ott (CIEMAT, Madrid)
    The MONSTER neutron time of flight setup at IGISOL
    The MOdular Neutron SpectromeTER (MONSTER) has been installed recently at the spectroscopy station of the IGISOL facility. It will be used for measuring the beta-delayed neutron decay of As-85. This experiment is the first in which the neutron detectors and the fully digital DAQ will be operated and thus serves also as a commissioning of the instrument.
  • March 12, 2019 at 13:15 in FYS3, Chandana Bhattacharya (Variable Energy Cyclotron Centre, Kolkata, India)
    Experimental nuclear facilities and nuclear reaction studies at VECC
    In recent years, our group at VECC is actively engaged in different experimental studies to explore the different aspects of nuclear reactions. These studies cover a broad range of topics spanning fragment emission mechanism, Fusion–fission, quasi fission, nuclear level density and its dependence on excitation energy and spin, cluster structure studies in light nuclei and transfer reactions for study of structure of nuclei of astrophysical interest. A review of above mentioned activities along with the existing experimental facilities will be presented in this talk.
  • February 21, 2019 at 15:15 in FYS3, Clément Delafosse (JYFL)
    In-flight and beta-delayed gamma spectroscopy in the vicinity of 78Ni with AGATA at GANIL and Bedo at ALTO

    While the N=50 shell-gap evolution towards 78Ni is presently in the focus of nuclear structure research, experimental information on the neutron effective single particle energy (ESPE) sequence above the 78Ni core remain scarce. Direct nucleon exchange reactions are indeed difficult with presently available post-accelerated radioactive ion beams (especially for high orbital momentum orbitals) in this exotic region. We have studied the evolution of the νg7/2 ESPE which is the key to understanding the possible evolution of the spin-orbit splitting due to the action of the proton-neutron interaction terms in the 78Ni region by measuring the lifetime of excited states in order to distinguish between collective and single-particle states. The evolution of the ESPE of this orbital, characterized by a high orbital momentum l=4, should indeed be particularly sensitive to tensor effects.

    In the continuity of an experiment performed in LNL-Legnaro [1], we performed an experiment at GANIL (Caen, France) with AGATA [2], VAMOS [3] and the Orsay plunger OUPS [4] in order to measure lifetime of Yrast excited states (in peculiar 7/21+ states) in several N=51 isotones populated by the reaction 238U(9Be,f). We particularly focused our study on 83Ge, the closest N=51 odd isotones to 79Ni for which detailed spectroscopy studies are possible within our experimental conditions. We also performed complementary β-delayed γ spectroscopy of 83Ge with BEDO [5] at the ALTO ISOL photo-fission facility in Orsay to investigate non-Yrast spectroscopy.

    Results from both experiments will be presented and discussed.

    [1] F. Didierjean et al., Phys. Rev. C 96, 044320 (2017)
    [2] E. Clément et al., NIM A 855 pp. 1-12 (2017)
    [3] H. Savajols et al., NIM B 204 pp. 146-153 (2003)
    [4] J. Ljungvall et al., NIM A 679 pp. 61-66 (2012)
    [5] A. Etile et al., PRC 91, 064317 (2015)
  • January 22, 2019 at 9:15 in FYS3. Sasha Zadvornaya (JYFL)
    Characterization of the supersonic gas jets for the in-gas-jet laser ionization spectroscopy method
    Laser spectroscopy studies give access to nuclear ground- and isomeric-state properties. With the in-gas-jet method, an extension of the In Gas Laser Ionization and Spectroscopy (IGLIS) technique [1], the spectral resolution can be improved by more than one order of magnitude in comparison to in-gas-cell ionization spectroscopy [2], while maintaining a high efficiency. An exhaustive characterization of the in-gas-jet method was performed at the IGLIS laboratory at KU Leuven using Planar Laser Induced Fluorescence (PLIF)-spectroscopy on copper atoms and will be presented in this seminar. The projected temperature associated (Doppler) broadening, that can be attained with the upgraded in-gas-jet method, was estimated to be about 140 MHz for the nobelium isotopes [3]. In addition to that, recent results of the characterization of subsonic flow inside IGISOL’s fission ion guide will be discussed at the seminar.
    [1] Yu. Kudryavtsev et al. Beams of short lived nuclei produced by selective laser ionization in a gas cell. Nucl. Instrum. Meth. Phys. Res. B, 114(3 4):350 – 365, 1996.
    [2] R. Ferrer et al. Towards high-resolution laser ionization spectroscopy of the heaviest elements in supersonic gas jet expansion. Nat. Commun., 8:14520, 2017.
    [3] A. Zadvornaya et al. Characterization of Supersonic Gas Jets for High Resolution Laser Ionization Spectroscopy of Heavy Elements. Phys. Rev. X, 8:041008, Oct 2018
     
  • December 12, 2018 at 14:15 in FYS3. Ronald Fernando Garcia Ruiz (ISOLDE, CERN)
    Shedding light on quantum many-body problems
    Atomic and molecular structures can be sensitive to observables that are key for our understanding of the nuclear many-body problem, the study of fundamental symmetries, and the search of new physics. This seminar will present recent results from precision laser spectroscopy experiments of exotic atoms and molecules at ISOLDE-CERN. The relevance of these results and their connection with the recent advances in nuclear, atomic and quantum chemistry theory will be discussed.
  • December 10, 2018 at 14:15 in FYS3. Simon Giraud (GANIL and LPC Caen)
    Study of core-collapse supernovae: nuclear physics inputs for a new NSE modeling
    The nuclear equation of state (EoS) and the electron-capture rates are among the main nuclear physics inputs used in core-collapse supernovae modeling. For these inputs, it is essential to know as precise as possible the nuclear masses because the distribution of populated microstates strongly depends on them. In addition, the values of nuclear masses enter directly in the calculations of the electron-capture rates, that, in turn, impact the neutrino flux which carries out 99% of the energy of the explosion.
    A recent sensitivity study, carried out by Sullivan et al. [1], pointed out that the nuclei playing the most important role during the core-collapse phase are located around 78Ni and 128Pd, which are at the N=50 and N=82 shell closures. More recently, using a new perturbative treatment of the extended Nuclear Statistical Equilibrium (NSE) model, we have shown that, along the collapse trajectory, nuclei seem indeed to concentrate around magic numbers. To this aim, we have applied the new approach to the Lattimer and Swesty (LS) EoS, considering a fixed representative core-collapse trajectory [2].
    The knowledge of the gap values for this nuclei of interest is thus essential. However, they rely on model predictions that may differ substantially. An experiment, that aimed to measure new nuclear masses and to improve those known around 78Ni using the JYFLTRAP Penning trap mass spectrometer at the IGISOL facility has been performed last year. The results obtained show that, the HFB-24 mass model is the one which reproduces better the experimental mass data and the N=40,50 and Z=28 gaps evolution far from stability, compared to the widely used DZ10 model. Therefore, they confirm the validity of the HFB-24 mass model far from stability and allow us to put more constraints on the neutron (N=40,50) and proton (Z=28) gap energies. Besides, new isomeric states have been also measured which could be of great interest for nuclear structure studies. Comparison with results obtained from shell model calculations using recent interactions is ongoing. Implementing consistently the new NSE-based model described above into a collapse numerical simulation, we will be able to quantify the impact of the shell effects based on our recent experimental results on the nuclear composition of the collapsing core.
    [1] C. Sullivan et al., ApJ 816, 44 (2016)
    [2] G. Grams, S. Giraud, A. F. Fantina, F. Gulminelli, PRC 97, 035807 (2018)
     
  • November 28, 2018 at 9:15 in FYS3. Julia Even (KVI-CART, University of Groningen) 
    What is NEXT? - Neutron-rich EXotic nuclei produced in multinucleon Transfer reactions. 
    Multi-nucleon transfer reactions using actinide targets hold the potential for the discovery of new isotopes in the transfermium region. These will provide access to information on the evolution of nuclear shell structure and fission half-lives in the heavy element region. Due to the large angular distribution of the transfer products, sample preparation for mass measurements and decay spectroscopy studies remains challenging a. So far, no separator dedicated to the production of heavy elements with multi-nucleon transfer reaction has been build.
    In the NEXT project, a solenoid spectrometer will be combined with a Multi Reflection-Time of Flight Mass Spectrometer (MR-ToF MS) in order to overcome experimental limitations. The solenoid spectrometer provides a large angular acceptance for transfer products. With help of the MR-ToF MS masses in the region around mendelevium towards the subneutron shell closure N=162 will be accessible. Furthermore the evolution of fission half-lives will be studied.
    In my presentation, I will present my NEXT project for which I recently received an ERC starting grant. 
  • November 27, 2018 at 9:15 in FYS3. Olga Beliuskina (JYFL)
    On the synthesis of neutron-rich isotopes along the N=126 shell in multinucleon transfer reactions
    We performed experimental and theoretical studies of deep inelastic multinucleon transfer reactions in heavy-ion collisions at Coulomb barrier energies. The goal was to investigate if deep inelastic transfer is superior to fragmentation reactions for producing neutron-rich isotopes in the astrophysically interesting region along the closed neutron shell N = 126. The experiment was performed at the velocity filter SHIP at GSI Darmstadt. Several transfer products on the neutron-rich side were populated but new isotopes were not observed. A comparison of the measured transfer cross-sections and production yields with those from fragmentation reactions allowed for interesting conclusions.
  • November 22, 2018 at 9:15 in FYS3. Bahadir Sayği (Ege University), Pseudo-mirror nuclei in the mass regions varying from A ~ 100 to A ~ 200.
  • November 20, 2018 at 9:15 in FYS3. Alexander Karpov (JINR, Dubna), How to produce neutron-rich heavy nuclei?
  • October 16, 2018 at 14:15 in FYS3. Khuyagbaatar Jadambaa (GSI Helmholtzzentrum für Schwerionenforschung & Helmholtz-Institut Mainz), β(EC) delayed fission in the heaviest nuclei
  • October 10, 2018 at 13:15 in FYS3. Frank Wienholtz (CERN), Lessons learned from the success of ISOLTRAP’s MR-TOF and a possible future 30-kV ISOLDE device
  • June  14, 2018 at 13:15 in FYS3. Boris Andel (Comenius University, Bratislava): Laser-assisted decay studies at ISOLDE: alpha decay of 180Tl and beta-delayed fission of 188Bi
  • April 25, 2018 at 15:15 in FYS3. Xiaofei Yang (Peking University, China): Investigating nuclear structure of exotic isotopes by laser spectroscopy 
  • April 19, 2018 at 14:15 in FYS3. Stuart Szwec (University of Jyväskylä): Probing nuclear structure using transfer reactions
  • April 13, 2018, at 13:15 in FYS3. Luca Marmugi (University College London): Ultra-cold Nuclear Matter: From Nuclear Radiuses to Collective Isomeric Decays
  • February 1, 2018, at 15:15 in FYS3. Muneer Sakildien (iThemba Labs, South Africa): An overview of the iThemba LABS facilities