4,617 research outputs found
First observation of 55,56Zn
In an experiment at the SISSI/LISE3 facility of GANIL, the most proton-rich
zinc isotopes 55,56Zn have been observed for the first time. The experiment was
performed using a high-intensity 58Ni beam at 74.5 MeV/nucleon impinging on a
nickel target. The identification of 55,56Zn opens the way to 54Zn, a good
candidate for two-proton radioactivity according to theoretical predictions.Comment: 2 pages, 1 figure, accepted for publication in Eur. Phys. J.
Decay of proton-rich nuclei between 39Ti and 49Ni
Decay studies of very neutron-deficient nuclei ranging from 39Ti to 49Ni have
been performed during a projectile fragmentation experiment at the GANIL/LISE3
separator. For all nuclei studied in this work, 39,40Ti, 42,43Cr, 46Mn,
45,46,47Fe and 49Ni, half-lives and decay spectra have been measured. In a few
cases, gamma coincidence measurements helped to successfully identify the
initial and final states of transitions. In these cases, partial decay scheme
are proposed. For the most exotic isotopes, 39Ti, 42Cr, 45Fe and 49Ni, which
are candidates for two-proton radioactivity from the ground state, no clear
evidence of this process is seen in our spectra and we conclude rather on a
delayed particle decay.Comment: 12 pages, 15 figures, submitted for publication in Eur. Phys. J.
Star formation around RCW 120, the perfect bubble
We take advantage of the very simple morphology of RCW 120 -- a perfect
bubble -- to understand the mechanisms triggering star formation around an HII
region and to establish what kind of stars are formed there. We present 870
microns observations of RCW 120, obtained with the APEX-LABOCA camera. These
show the distribution of cold dust, and thus of neutral material. We use
Spitzer-MIPS observations at 24 and 70 microns to detect the young stellar
objects (YSOs) present in this region and to estimate their evolutionary
stages.
A layer of dense neutral material surrounds the HII region, having been swept
up during the region's expansion. This layer has a mass greater than 2000 solar
masses and is fragmented, with massive fragments elongated along the ionization
front (IF). We measured the 24 microns flux of 138 sources. Of these, 39 are
Class I or flat-spectrum YSOs observed in the direction of the collected layer.
We show that several triggering mechanisms are acting simultaneously in the
swept-up shell, where they form a second generation of stars. No massive YSOs
are detected. However, a massive, compact 870 microns core lies adjacent to the
IF. A 70 microns source with no 24 microns counterpart is detected at the same
position. This source is a likely candidate for a Class 0 YSO. Also at 24
microns, we detect a chain of about ten regularly spaced Class I or flat
spectrum sources, parallel to the IF, in the direction of the most massive
fragment. We suggest that the formation of these YSOs is the result of Jeans
gravitational instabilities in the collected layer. Finally, the 870 microns
emission, the 24 microns emission, and the Halpha emission show the existence
of an extended and partially ionized photodissociation region around RCW 120.Comment: 14 pages, 17 figure
On the discovery of doubly-magic Ni
The paper reports on the first observation of doubly-magic Nickel-48 in an
experimental at the SISSI/LISE3 facility of GANIL. Four Nickel-48 isotopes were
identified. In addition, roughly 100 Nickel-49, 50 Iron-45, and 290 Chromium-42
isotopes were observed. This opens the possibility to search for two-proton
emission from these nuclei.Comment: 4 pages, 3 figures, accepted for publication in Phys. Rev. Let
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