P. Golubev

New Short-Lived Isotope 221U and the Mass Surface Near N=126

Two short-lived isotopes ^{221}U and ^{222}U were produced as evaporation residues in the fusion reaction ^{50}Ti+^{176}Yb at the gas-filled recoil separator TASCA. An α decay with an energy of E_{α}=9.31(5)  MeV and half-life T_{1/2}=4.7(7)  μs was attributed to ^{222}U. The new isotope ^{221}U was identified in α-decay chains starting with E_{α}=9.71(5)  MeV and T_{1/2}=0.66(14)  μs leading to known daughters. Synthesis and detection of these unstable heavy nuclei and their descendants were achieved thanks to a fast data readout system. The evolution of the N=126 shell closure and its influence on the stability of uranium isotopes are discussed within the framework of α-decay reduced width.

The Large Enriched Germanium Experiment for Neutrinoless Double Beta Decay (LEGEND)

The observation of neutrinoless double-beta decay (0νββ) would show that lepton number is violated, reveal that neu-trinos are Majorana particles, and provide information on neutrino mass. A discovery-capable experiment covering the inverted ordering region, with effective Majorana neutrino masses of 15 - 50 meV, will require a tonne-scale experiment with excellent energy resolution and extremely low backgrounds, at the level of ∼0.1 count /(FWHM·t·yr) in the region of the signal. The current generation 76Ge experiments GERDA and the Majorana Demonstrator, utilizing high purity Germanium detectors with an intrinsic energy resolution of 0.12%, have achieved the lowest backgrounds by over an order of magnitude in the 0νββ signal region of all 0νββ experiments. Building on this success, the LEGEND collaboration has been formed to pursue a tonne-scale 76Ge experiment. The collaboration aims to develop a phased 0νββ experimental program with discovery potential at a half-life approaching or at 1028 years, using existing resources as appropriate to expedite physics results.

Energy calibration of CsI(T1) scintillator in pulse-shape identification technique

A batch of 16 CsI(TI) scintillator crystals, supplied by the Bicron Company, has been studied with respect to precise energy calibration in pulse-shape identification technique. The light corresponding to pulse integration within the time interval 1.6-4.5 mus (long gate) and 0.0-4.5 mus (extra-long gate) exhibits a power law relation, L(E, Z, A) a1 (Z, A)Ea2(Z-4), for (1.2.3) H isotopes in the measured energy range 5-150 MeV. For the time interval 0.0-0.60 mus (short gate), a significant deviation from the power law relation is observed, for energy greater than similar to30 MeV. The character of the a2(p)-a2(d) and a2(p)-a2(t) correlations for protons, deuterons and tritons, reveals 3 types of crystals in the batch. These subbatches differ in the value of the extracted parameter a2 for protons, and in the value of the spread of a2 for deuterons and tritons. This may be explained by the difference in the energy dependence of the fast decay time component and/or by the difference in the light output ratio of the fast/slow components. An accuracy well inside 1.0% is achieved in the energy calibration of the CsI(TI) crystals by using the DeltaE(Si) E(CsI(Tl))/PMT method. The batch of 16 CsI(TI) crystals is utilized to measure the correlations of light charged particles produced in E/A = 61 MeV, (36)Arinduced reactions. The preliminary correlation functions for two protons with small relative momenta are presented

Isospin effects on two-particle correlation functions in E/A=61 MeV Ar-36+Sn-112,Sn-124 reactions

Small-angle, two-particle correlation functions have been measured for Ar-36+Sn-112,Sn-124 collisions at E/A=61 MeV. Total momentum gated neutron-proton (np) and proton-proton (pp) correlations are stronger for the Sn-124 target. Some of the correlation functions for particle pairs involving deuterons or tritons (nd, pt, and nt) also show a dependence on the isospin of the emitting source.

CHICSi – a Compact Ultra-High Vacuum Compatible Detector System for Nuclear Reaction Experiments at Storage Rings. I. General Structure, Mechanics and UHV Compatibility

CELSIUS Heavy-Ion Collision Silicon detector system (CHICSi) is a large solid angle, barrel-shaped detector system, housing up to 600 detector telescopes arranged in rotational symmetry around the beam axis. CHICSi measures charged particles and fragments from nuclear reactions. It operates at internal targets of storage rings. In order to optimize space and momentum-space coverage and minimize the low-energy detection limits, CHICSi is designed for use in ultra-high vacuum (UHV, similar to 10(-8) Pa) inside a cluster-jet target chamber. This calls for materials in mechanical support, detectors, Very Large Scale Integrated (VLSI) electronics, connectors, cables and other signal transport devices with very low outgassing. Two auxiliary detector systems, which will operate in coincidence with CHICSi, a heavy-recoil, time-of-flight system (HR-TOF) also placed inside the target chamber and a projectile fragmentation wall (PF-WALL) located outside the chamber, have also been constructed. In total, this combined system registers more than 80% of all charged particles and fragments from typical heavy-ion reactions at energies of a few hundreds of MeV per nucleon

High-precision mass measurements for the isobaric multiplet mass equation at A = 52

Masses of 52Co, 52Com, 52Fe, 52Fem, and 52Mn have been measured with the JYFLTRAP double Penning trap mass spectrometer. The isobaric multiplet mass equation for the T = 2 quintet at A = 52 has been studied employing the new mass values. No significant breakdown (beyond the level) of the quadratic form of the IMME was observed (). The cubic coefficient was 6.0(32) keV (). The excitation energies for the isomer and the T = 2 isobaric analog state in 52Co have been determined to be 374(13) keV and 2922(13) keV, respectively. The measured mass values for 52Co and 52Com are 29(10) keV and 16(15) keV higher, respectively, than obtained in a recent storage-ring experiment, and significantly lower than predicted by extrapolations. Consequently, this has an impact on the proton separation energies for 52Co and 53Ni relevant for the astrophysical rapid proton capture process. The Q value for the proton decay from the isomer in 53Co has been determined with an unprecedented precision, keV. (Less)

New sequence-based data on the relative DNA contents of chromosomes in the normal male and female human diploid genomes for radiation molecular cytogenetics

BackgroundThe objective of this work is to obtain the correct relative DNA contents of chromosomes in the normal male and female human diploid genomes for the use at FISH analysis of radiation-induced chromosome aberrations.ResultsThe relative DNA contents of chromosomes in the male and female human diploid genomes have been calculated from the publicly available international Human Genome Project data. New sequence-based data on the relative DNA contents of human chromosomes were compared with the data recommended by the International Atomic Energy Agency in 2001. The differences in the values of the relative DNA contents of chromosomes obtained by using different approaches for 15 human chromosomes, mainly for large chromosomes, were below 2%. For the chromosomes 13, 17, 20 and 22 the differences were above 5%.ConclusionNew sequence-based data on the relative DNA contents of chromosomes in the normal male and female human diploid genomes were obtained. This approach, based on the genome sequence, can be recommended for the use in radiation molecular cytogenetics.

Pion emission in H-2, C-12, Al-27(gamma, pi(+)) reactions at threshold

The first data from MAX-lab in Lund, Sweden on pion production in photonuclear reactions at threshold energies, is presented. The decrease of the total yield of pi+ in gamma + 12C, 27Al reactions below 200 MeV as well as differential, dsigma/dOmega, cross sections follow essentially predictions from an intranuclear cascade model with an attractive potential for pion-nucleus interaction in its simplest form. Double differential, d2sigma/dOmegadT, cross sections at 176 MeV show, however, deviations from the model, which call for refinements of nuclear and Coulomb potentials and possibly also for coherent pion production mechanisms.

Upgrade and Commissioning of the Lund-York-Cologne CAlorimeter

The neutron-rich nuclei 33P and 33S in the upper sd-shell were investigated by means of the 26Mg(13C,npa) and 26Mg(13C,2na) fusion-evaporation reactions. Excited states with intermediate and high spins have been populated. The level schemes of both nuclei have been considerably extended. Utilizing the gammagamma-angular correlation method the spin-parity assignment of the new excited states in 33P has been investigated. The experimentally determined energy levels as well as the known reduced transition probabilities (i.e. B(M1) and B(E2) values) from both nuclei were compared to 0hbaromega and 1hbaromega truncated p-sd-pf shell-model calculations using the PSDPF interaction. For the energy levels a very good agreement between experiment and theory was shown for both 33P and 33S. However, for B(M1) and B(E2) values the calculated values cannot reproduce the experimental results with satisfying agreement for all transitions. In some places the discrepancy between experiment and theory is even large, which requires further experimental as well as theoretical investigation of this thesis for these nuclei. The second part was focused on the upgrade and commissioning tests of the Lund- York-Cologne CAlorimeter (LYCCA). As a key device of the High resolution In-flight SPECtroscopy (HISPEC) campaign of the FAIR/NUSTAR collaboration, LYCCA was designed to identify the reaction products after the secondary target, as well as to track the particle trajectory event by event. After the successful employment of the precursor LYCCA-0 in the PreSPEC campaign, the electronic as well as mechanic components of the LYCCA system were upgraded by STFC Daresbury Laboratory. Using the high integrated AIDA Front-End electronics with ASICs the signals from more than thousand DSSSD-channels were pre-amplified and processed. Since 2016, the new LYCCA setup is located at the Cologne tandem accelerator. Triple-Alpha tests and in-beam experiments of elastic scattering were carried out to check the specifications of the system after the upgrade. The obtained results allow first important conclusions about energy resolution and efficiency of the calorimeter at low energies for future NUSTAR experiments.Di Nitto, A.; Khuyagbaatar, J.; Ackermann, D.; Adamczewski-Musch, J.; Andersson, LiseLotte; Badura, E.; Block, M; Brand, H.; Cox, D. M.; Düllmann, Ch. E.; Dvorak, J.; Eberhardt, K.; Ellison, P. A.; Esker, N. E.; Even, J.; Fahlander, Claes; Forsberg, Ulrika; Gates, J.M.; Golubev, Pavel; Gothe, O.; Gregorich, K.E.; Hartmann, W.; Herzberg, R.-D.; Heßberger, F. P.; Hoffmann, J.; Hollinger, R.; Hübner, A.; Jäger, E.; Jeppsson, J.; Kindler, B.; Klein, S.; Kojouharov, I.; Kratz, J.V.; Krier, J.; Kurz, N.; Lahiri, S.; Linev, S.; Lommel, B.; Maiti, M.; Mändl, R.; Merchán, E.; Minami, S.; Mistry, A. K.; Mokry, Ch.; Nitsche, H.; Omtvedt, J. P.; Pang, G.; Pysmenetska, I.; Renisch, D.; Rudolph, Dirk

Identification of Reaction Products in 50Ti+249Cf Reactions at TASCA

The neutron-rich nuclei 33P and 33S in the upper sd-shell were investigated by means of the 26Mg(13C,npa) and 26Mg(13C,2na) fusion-evaporation reactions. Excited states with intermediate and high spins have been populated. The level schemes of both nuclei have been considerably extended. Utilizing the gammagamma-angular correlation method the spin-parity assignment of the new excited states in 33P has been investigated. The experimentally determined energy levels as well as the known reduced transition probabilities (i.e. B(M1) and B(E2) values) from both nuclei were compared to 0hbaromega and 1hbaromega truncated p-sd-pf shell-model calculations using the PSDPF interaction. For the energy levels a very good agreement between experiment and theory was shown for both 33P and 33S. However, for B(M1) and B(E2) values the calculated values cannot reproduce the experimental results with satisfying agreement for all transitions. In some places the discrepancy between experiment and theory is even large, which requires further experimental as well as theoretical investigation of this thesis for these nuclei. The second part was focused on the upgrade and commissioning tests of the Lund- York-Cologne CAlorimeter (LYCCA). As a key device of the High resolution In-flight SPECtroscopy (HISPEC) campaign of the FAIR/NUSTAR collaboration, LYCCA was designed to identify the reaction products after the secondary target, as well as to track the particle trajectory event by event. After the successful employment of the precursor LYCCA-0 in the PreSPEC campaign, the electronic as well as mechanic components of the LYCCA system were upgraded by STFC Daresbury Laboratory. Using the high integrated AIDA Front-End electronics with ASICs the signals from more than thousand DSSSD-channels were pre-amplified and processed. Since 2016, the new LYCCA setup is located at the Cologne tandem accelerator. Triple-Alpha tests and in-beam experiments of elastic scattering were carried out to check the specifications of the system after the upgrade. The obtained results allow first important conclusions about energy resolution and efficiency of the calorimeter at low energies for future NUSTAR experiments.Di Nitto, A.; Khuyagbaatar, J.; Ackermann, D.; Adamczewski-Musch, J.; Andersson, LiseLotte; Badura, E.; Block, M; Brand, H.; Cox, D. M.; Düllmann, Ch. E.; Dvorak, J.; Eberhardt, K.; Ellison, P. A.; Esker, N. E.; Even, J.; Fahlander, Claes; Forsberg, Ulrika; Gates, J.M.; Golubev, Pavel; Gothe, O.; Gregorich, K.E.; Hartmann, W.; Herzberg, R.-D.; Heßberger, F. P.; Hoffmann, J.; Hollinger, R.; Hübner, A.; Jäger, E.; Jeppsson, J.; Kindler, B.; Klein, S.; Kojouharov, I.; Kratz, J.V.; Krier, J.; Kurz, N.; Lahiri, S.; Linev, S.; Lommel, B.; Maiti, M.; Mändl, R.; Merchán, E.; Minami, S.; Mistry, A. K.; Mokry, Ch.; Nitsche, H.; Omtvedt, J. P.; Pang, G.; Pysmenetska, I.; Renisch, D.; Rudolph, Dirk