137 research outputs found
Magnetic Moment of the Fragmentation Aligned 61Fe(9/2)+ Isomer
We report on the g factor measurement of the isomer in (). The isomer was produced and spin-aligned via a projectile-fragmentation
reaction at intermediate energy, the Time Dependent Perturbed Angular
Distribution (TDPAD) method being used for the measurement of the g factor. For
the first time, due to significant improvements of the experimental technique,
an appreciable residual alignment of the isomer has been observed, allowing a
precise determination of its g factor: . Comparison of the
experimental g factor with shell-model and mean field calculations confirms the
spin and parity assignments and suggests the onset of deformation due
to the intrusion of Nilsson orbitals emerging from the .Comment: 4 figures. Submitted to Phys. Rev. Let
New pathway to bypass the 15O waiting point
We propose the sequential reaction process
O(,)O as a new pathway to bypass of the
O waiting point. This exotic reaction is found to have a surprisingly
high cross section, approximately 10 times higher than the
O(,)O. These cross sections were calculated after
precise measurements of energies and widths of the proton-unbound F low
lying states, obtained using the H(O,p)O reaction. The large
cross section can be understood to arise from the more
efficient feeding of the low energy wing of the ground state resonance by the
gamma decay. The implications of the new reaction in novae explosions and X-ray
bursts are discussed.Comment: submitte
Inverse kinematics proton scattering from the exotic nucleus O
NESTER PTHInternational audienceWe have measured for the first time elastic and inelastic proton scattering from the neutron rich nucleus 22O at 46.6 AMeV using the MUST array
The N=14 shell closure in O viewed through a neutron sensitive probe
NESTER PTHInternational audienceTo investigate the behavior of the N=14 neutron gap far from stability with a neutron-sensitive probe, proton elastic and 2+1 inelastic scattering angular distributions for the neutron-rich nucleus 22O were measured with a secondary beam intensity of only 1200 particles per second using the MUST silicon strip detector array at the GANIL facility. A phenomenological analysis yields a deformation parameter bp;p' = 0.26 +- 0.04 for the 2+1 state, much lower than in 20O, showing a surprisingly weak neutron contribution to this state. A fully microscopic analysis was performed using optical potentials obtained from matter and transition densities generated by continuum Skyrme-HFB and QRPA calculations, respectively. When the present results and those from a 22O + 197Au scattering experiment are combined, the ratio of neutron to proton contributions to the 2+1 state is found close to the N/Z ratio, demonstrating a strong N=14 shell closure in the vicinity of the neutron drip-line
First g(2+) measurement on neutron-rich 72 Zn, and the high-velocity transient field technique for radioactive heavy-ion beams
The high-velocity transient-field (HVTF) technique was used to measure the g factor of the 2+ state of 72Zn produced as a radioactive beam. The transient-field strength was probed at high velocity in ferromagnetic iron and gadolinium hosts using 76Ge beams. The potential of the HVTF method is demonstrated and the difficulties that need to be overcome for a reliable use of the TF technique with high-Z, high-velocity radioactive beams are revealed. The polarization of K-shell vacancies at high velocity, which shows more than an order of magnitude difference between Z = 20 and Z = 30 is discussed. The g-factor measurement hints at the theoretically predicted transition in the structure of the Zn isotopes near N = 40
Study of ÎČ-delayed charged particle emission of 11Li: Evidence of new decay channels
5 pags., 3 figs. -- 9th International Conference on Clustering Aspects of Nuclear Structure and Dynamics (CLUSTERS'07) 3â7 September 2007, Stratford upon Avon, UKThe break-up of the 18.2 MeV state in 11Be was studied in a 11Li ÎČ-decay experiment. We report here on the study of the dominating breakup channels involving na6He or 3n2α in the final state, with special emphasis dedicated in this contribution to the three-particle channel. The two emitted charged particles were detected in coincidence using a highly segmented experimental set-up. The observed experimental energy-vs-energy scatter plot indicates a sequential breakup where nuclei of mass 4, alpha particles, and mass 7, 7He, are involved. A Monte-Carlo simulation of the sequential channel, 11Be* â α + 7He â nα6He was performed and compared to the experimental data and to a simulation of the direct break-up of the 18.2 MeV state nα6He by phase space energy distribution. The energy-versus-energy plot are explained by the sequential simulation but not by the phase space simulation. © 2008 IOP Publishing Ltd
Is the 7/2^<->_<1> isomer state of ^<43>S spherical?
We report on the spectroscopic quadrupole moment measurement of the 7/2â1 isomeric state in S271643 [Eâ=320.5(5)ââkeV, T1/2=415(3)ââns], using the time dependent perturbed angular distribution technique at the RIKEN RIBF facility. Our value, âŁQsâŁ=23(3)ââefm2, is larger than that expected for a single-particle state. Shell model calculations using the modern SDPF-U interaction for this mass region reproduce remarkably well the measured âŁQsâŁ, and show that non-negligible correlations drive the isomeric state away from a purely spherical shape
Precision measurement of the electric quadrupole moment of 31Al and determination of the effective proton charge in the sd-shell
he electric quadrupole coupling constant of the 31Al ground state is measured
to be nu_Q = |eQV_{zz}/h| = 2196(21)kHz using two different beta-NMR (Nuclear
Magnetic Resonance) techniques. For the first time, a direct comparison is made
between the continuous rf technique and the adiabatic fast passage method. The
obtained coupling constants of both methods are in excellent agreement with
each other and a precise value for the quadrupole moment of 31Al has been
deduced: |Q(31Al)| = 134.0(16) mb. Comparison of this value with large-scale
shell-model calculations in the sd and sdpf valence spaces suggests that the
31Al ground state is dominated by normal sd-shell configurations with a
possible small contribution of intruder states. The obtained value for
|Q(31Al)| and a compilation of measured quadrupole moments of odd-Z even-N
isotopes in comparison with shell-model calculations shows that the proton
effective charge e_p=1.1 e provides a much better description of the nuclear
properties in the sd-shell than the adopted value e_p=1.3 e
New approach to the nuclear in beam spectroscopy of neutron rich nuclei at N=20 using projectile fragmentation
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An above-barrier narrow resonance in <sup>15</sup>F
Intense and purified radioactive beam of post-accelerated O was used
to study the low-lying states in the unbound F nucleus. Exploiting
resonant elastic scattering in inverse kinematics with a thick target, the
second excited state, a resonance at E=4.757(6)(10)~MeV with a width of
=36(5)(14)~keV was measured for the first time with high precision. The
structure of this narrow above-barrier state in a nucleus located two neutrons
beyond the proton drip line was investigated using the Gamow Shell Model in the
coupled channel representation with a C core and three valence protons.
It is found that it is an almost pure wave function of two quasi-bound protons
in the shell.Comment: 8 pages, 2 figures, 1 table, Submitted to Phys. Lett.
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