N. Mărginean

Excited states in {sup 52}Fe and the origin of the yrast trap at I{sup {pi}}=12{sup +}

Excited states in {sup 52}Fe have been studied up to spin 10{h_bar} in the reaction {sup 28}Si+{sup 28}Si at 115 MeV beam energy by using in-beam {gamma}-ray spectroscopy methods at the GASP array. The excitation energy of the yrast 10{sup +} state is 7.381 MeV, almost 0.5 MeV above the well known {beta}{sup +}-decaying yrast 12{sup +} state. Experimental upper limits for the B(E4) transition probabilities from the 12{sup +} isomer to the 8{sub 1}{sup +} and 8{sub 2}{sup +} states have been determined. The mean lifetimes of five excited states have been measured by using the Doppler shift attenuation method. Complete diagonalizations in the pf major shell lead to very good agreement with the experimental level scheme and transition probabilities. The lifetime, log ft value, branching ratios, and B(E4) values are calculated for the 12{sup +} isomer. The positive parity states are also interpreted in terms of a Nilsson projected method. The structure of the yrast levels of {sup 52}Fe is compared with those of its cross conjugate {sup 44}Ti. {copyright} {ital 1998} {ital The American Physical Society}

Lifetimes in the middle of 1f7/2 shell: cross-conjugated nuclei 47V and 49Cr

DSAM lifetimes have been determined in the middle of 1f7/2 shell for the cross-conjugated nuclei 47 Va nd 49 Cr, populated with the reaction 28 Si on 28 Si at 115 MeV using a Au backed target. B(E2) and B(M1) reduced rates agree very well with large scale shell model predictions. The interplay between spherical and collective structures is discussed.  2001 Elsevier Science B.V. All rights reserved.

Improvements of the research infrastructure at the tandem laboratory in IFIN-HH

An extensive process of modernizing the research infrastructure started 6 years ago at the tandem accelerator in IFIN-HH. Major improvements of the 9 MV FN tandem accelerator installed in IFIN-HH in ′73 were done in the late years, making it a very reliable machine, suited for basic and applied research experiments. The developments opened the way for new experiments made for the first time in our laboratory. Two new Cockroft-Walton tandem accelerators were also installed in 2012. The 1 MV HVE Tandetron accelerator is dedicated to AMS measurements, especially for 14C dating, while the 3 MV HVE Tandetron accelerator has the reaction chambers and detection system prepared for ion beam analysis measurements, microprobe experiments and ion implantation.

7Li-induced reactions for fast-timing with LaBr3:Ce detectors

7Li induced-reactions have been used with a 186W target to populate nuclei around A∼180-190 at the National Institute of Physics and Nuclear Engineering in Bucharest, Romania. An array of high-purity germanium (HPGe) and cerium-doped lanthanum bromide (LaBr3:Ce) detectors have been used to measure sub-nanosecond half-lives with fast-timing techniques. The yrast 2+ state in 190Os was measured to be t1/2 = 375(20)ps, in excellent agreement with the literature value. The previously unreported half-life of the 564-keV state in 189Ir has also been measured and a value of t1/2 = 540(100)ps ps obtained.

Toward the N = 40 sub-shell closure in Co isotopes and the new island of inversion

Neutron-rich Co isotopes from N = 34 to 40 were studied through multinucleon transfer by bombarding a 238U target with a 460 MeV 70Zn beam at the Legnaro National Laboratories. Gamma-recoil coincidences were recorded identifying the ions by using a high-acceptance magnetic spectrometer (PRISMA) and detecting the gamma radiation by using an array of HPGe clover detectors (CLARA). The results are discussed in comparison with the predictions of large-scale shell-model calculations.

New nuclei around the NZ line in the A = 80–90 Region

Abstract The first identification of gamma-rays from excited states of the 85 Mo and 88 Ru nuclei is reported, together with a short discussion of the evolution of the nuclear structure along the N = Z and the N = 43, 44 lines.

Isospin Symmetry Along The N=Z Line In The sd Shell

Excited states have been studied in sd‐shell nuclei following the 16O (70 MeV) + 24Mg (400 μg/cm2) fusion‐evaporation reaction. The GASP spectrometer in conjunction with the charged‐particle detector ISIS and the Neutron ring allowed the detection of the γ‐rays in coincidence with evaporated light particles. New data on the mirror pairs A=31 and A=35 have been obtained. In particular, the comparison between the level schemes of 35Ar and 35Cl has confirmed the importance of the electromagnetic spin‐orbit term, which explains the large Mirror Energy Difference values. Evidence of isospin mixing can be deduced from the E1 transitions.

Preparation and characterization of strontium targets for nuclear astrophysics experiments

The present paper describes preparation and characterization of strontium targets for nuclear astrophysical experiments with alpha particles accelerated near the Gamow window energy. SrF2 and SrCO3 targets were obtained by thermal evaporation in similar conditions. Target characteristics (thickness, chemical purity and surface morphology) were determined via α transmission measurements, XRD and SEM/EDX analysis. The results reveal the SrF2 target exhibits better properties compared to the SrCO3 one for our nuclear astrophysics experiments. This result was supported by nuclear activation measurements with an α beam at the Bucharest Tandem 9 MV accelerator.

Experimental study of neutron-rich nuclei near the N=82 closed shell using the Zr-96(40)+Sn-124(50) reaction with GASP and PRISMA-CLARA arrays

In this contribution an experimental study of the deep-inelastic reaction 4096Zr+50124Sn at 530 MeV, using the GASP and PRISMA-CLARA arrays, is presented. The experiments populate a wealth of projectile-like and target-like binary fragments, in a large neutron-rich region around N ≥ 50 and Z ≈ 40. Preliminary results on the study of the yrast and near-yrast states for 95Nb will be shown, along with a comparison of the experimental yields obtained in the experiments.

Low-lying isomeric states inGa80from theβ−decay ofZn80

A new level scheme of 80Ga has been determined. This nucleus was populated following the β− decay of 80Zn at ISOLDE, CERN. The proposed level scheme is significantly different compared to the previously reported one and contains 26 levels up to 3.4 MeV in excitation energy. The present study establishes that the previously identified 1.9-s β− -decaying 6− isomer is the ground state of 80Ga and the 1.3-s β− -decaying 3− isomer lies at an excitation energy of 22.4 keV. A new isomeric level was identified at 707.8 keV and its half-life was measured to be 18.3(5) ns, allowing the 685.4-keV transition de-exciting this state to be assigned anM2 multipolarity. The newly measured spectroscopic observables are compared with shell-model calculations using the jj44bpn and JUN45 interactions.