R. Kanungo

Experiment on the Synthesis of Element 113 in the Reaction 209Bi(70Zn,n)278113

The convincing candidate event of the isotope of the 113th element, 278 113, and its daughter nuclei, 274 111 and 270 Mt, were observed, for the first time, in the 209 Bi + 70 Zn reaction at a beam energy of 349.0 MeV with a total dose of 1.7 ×10 19 . Alpha decay energies and decay times of the candidates, 278 113, 274 111, and 270 Mt, were (11.68 ±0.04 MeV, 0.344 ms), (11.15 ±0.07 MeV, 9.26 ms), and (10.03 ±0.07 MeV, 7.16 ms), respectively. The production cross section of the isotope was deduced to be 55 +150 -45 fb (10 -39 cm 2 ).

Observation of new neutron and proton magic numbers

Abstract Systematics of beta decay Q values, single neutron separation energies, and the energies of the first excited state for even–even nuclei have been studied for neutron-rich nuclei. Breaks in systematics of these three quantities show the existence of new magic numbers at Z =16 and N =30 in neutron-rich regions of nuclear chart. Shell closure at N =32 is also observed. The recently reported new magic number N =16 has been reconfirmed also in this analysis from new view points.

TIGRESS: TRIUMF-ISAC gamma-ray escape-suppressed spectrometer

The TRIUMF-ISAC gamma-ray escape-suppressed spectrometer (TIGRESS) is a new γ-ray detector array being developed for use at TRIUMFs Isotope Separator and Accelerator (ISAC) radioactive ion beam facility. TIGRESS will comprise 12 32-fold segmented clover-type HPGe detectors coupled with 20-fold segmented modular Compton suppression shields and custom digital signal processing electronics. This paper provides an overview of the TIGRESS project and progress in its development to date.

Production and decay properties of 272111 and its daughter nuclei

The production and decay of 272 111 has been investigated using a gas-filled recoil ion separator in irradiations of 209 Bi targets with 64 Ni beam at 320, 323 and 326 MeV. We have observed 14 α-decay chains in total, that can be assigned, on the basis of their time correlations, to subsequent decays from 272 111 produced in the 209 Bi( 64 Ni,1n) reaction. The present result is the first clear confirmation for the discovery of 272 111 and its α-decay products, 264 Bh and 268 Mt, reported previously by a GSI group. New information on their half-lives and decay energies as well as the excitation function is presented.

Halo structure in 19C: a Glauber model analysis

Abstract The recently available 19 C+ 12 C interaction cross section data at E lab =960 A MeV and the longitudinal momentum distribution data at E lab =910 A MeV and 88 A MeV have been analyzed in a Glauber model approach to investigate the possible ground state configuration of the 19 C nucleus. A comparative analysis of both these experimental data fails to yield a consistent conclusion regarding possible ground state configuration within the 1 σ experimental error bar. It is suggested that a considerable change of the core of 19 C from the bare 18 C nucleus may take place.

Possibility of enlarged core structure of N = 15 neutron-rich nuclei

Abstract The recently measured interaction cross section data for 22 N, 23 O, and 24 F in a 12 C target at relativistic energies have been analysed in a few body Glauber model approach. Conventional fixed core-plus-neutron model for halo nuclei is unable to explain the observed enhanced cross section for these nuclei by any selection of the neutron orbitals. Microscopic calculations like many-body Monte Carlo shell model, relativistic mean field theory and cluster model are also shown to fail in describing the large difference if interaction cross section between 22 O and 23 O. A possibility of core enlargement is suggested in these nuclei.

Physics with reaccelerated radioactive beams at TRIUMF-ISAC

The TRIUMF-ISAC radioactive beam facility provides reaccelerated beams in the energy range from 0.15 to 5 A MeV for A < 30 to a full suite of world class experimental apparatus, enabling a forefront research program focused on understanding the evolution of nuclear structure towards the limits of existence and the origin of the chemical elements in the universe. Recent ISAC science highlights and future objectives are presented.

Lifetime of 19 Ne * (4.03 MeV)

The Doppler-shift attenuation method was applied to measure the lifetime of the 4.03 MeV state in {sup 19}Ne. By utilizing a {sup 3}He-implanted Au foil as a target, the state was populated using the {sup 20}Ne({sup 3}He, {alpha}){sup 19}Ne reaction in inverse kinematics at a {sup 20}Ne beam energy of 34 MeV. De-excitation {gamma} rays were detected in coincidence with {alpha} particles. At the 1{sigma} level, the lifetime was determined to be 11{sub -3}{sup +4} fs and at the 95.45% confidence level the lifetime is 11{sub -7}{sup +8} fs.

Structure of 55Ti from relativistic one-neutron knockout

Results are presented from a one-neutron knockout reaction at relativistic energies on 56Ti using the GSI FRS as a two-stage magnetic spectrometer and the Miniball array for gamma-ray detection. Inclusive and exclusive longitudinal momentum distributions and cross-sections were measured enabling the determination of the orbital angular momentum of the populated states. First-time observation of the 955(6) keV -hole state in 55Ti is reported. The measured data for the first time proves that the ground state of 55Ti is a 1/2- state, in agreement with shell-model calculations using the GXPF1A interaction that predict a sizable N=34 gap in 54Ca.

Measurement of 42 MeV 7Li projectile breakup on 58Ni target beyond grazing incidence

Abstract Angular distributions of the elastic and breakup cross sections of 42 MeV 7 Li-projectile on 58 Ni target are measured at wide angles beyond the grazing angle. Coincidence measurements are done at unequal angle pairs. In this angular region, the direct breakup is found to be very small and strongly dominated by the nuclear breakup process, while the sequential breakup contributions from the decay of the 7 2 − , 4.63 MeV resonant state of 7 Li remain significantly large within its corresponding sequential cone. Some indications of contributions from the higher sequential states ( 5 2 − 6.68 MeV, 5 2 − 7.46 MeV) are found.