335 research outputs found
Two-pion production in deuteron-deuteron collisions at low energies
The cross section for the dd -> 4He pi pi reaction is estimated near
threshold in a two-step model where a pion created in a first interaction
produces a second pion in a subsequent interaction. This approach, which
describes well the rates of 2pi and eta production in the pd -> 3He pi pi and
dd -> 4He eta reactions, leads to predictions that are much too low compared to
experiment. Alternatives to this and the double-Delta model will have to be
sought to explain these data.Comment: 5 pages with 4 postscript figure
Clarification of the low-lying states of Be-9
5 pages, 1 table, 2 figures.-- Presented at the
International Conference on Finite Fermionic Systems: Nilsson Model 50 years (Lund University, Sweden, June 14–18, 2005).--
PACS nrs.: 23.40.Hc, 27.20.+n, 24.80.+y.A newly developed technique for dealing with three-body decays of broad isolated levels is extended to deal with the broad, overlapping levels found at 2-9 MeV excitation energy in Be-9. The levels are populated through beta-decay of Li-9. The method gives firm evidence for the existence of several levels. Angular correlation studies allow spin values to be assigned.Peer reviewe
Systematic trends in beta-delayed particle emitting nuclei: The case of beta-p-alpha emission from 21Mg
We have observed beta+-delayed alpha and p-alpha emission from the
proton-rich nucleus 21Mg produced at the ISOLDE facility at CERN. The
assignments were cross-checked with a time distribution analysis. This is the
third identified case of beta-p-alpha emission. We discuss the systematic of
beta-delayed particle emission decays, show that our observed decays fit
naturally into the existing pattern, and argue that the patterns are to a large
extent caused by odd-even effects.Comment: 6 pages, 5 figure
Theoretical Description of the pd -> pd eta Reaction Near Threshold
The contributions of three different types of driving terms are included in
the estimation of the pd -> pd eta reaction at low energies. Near threshold, it
is predicted that a two-step model involving an intermediate pion should be the
most important but, as the energy approaches the threshold for eta production
in the free nucleon--nucleon reaction, a pick-up mechanism with a spectator
proton should become dominant. The total cross sections are underestimated by
about a factor of two compared to experimental data but the discrepancies in
the angular distributions are more serious, with no sign in the data for the
peaks corresponding to the pick--up diagram
Beta-delayed deuteron emission from 11Li: decay of the halo
The deuteron-emission channel in the beta-decay of the halo-nucleus 11Li was
measured at the ISAC facility at TRIUMF by implanting post-accelerated 11Li
ions into a segmented silicon detector. The events of interest were identified
by correlating the decays of 11Li with those of the daughter nuclei. This
method allowed the energy spectrum of the emitted deuterons to be extracted,
free from contributions from other channels, and a precise value for the
branching ratio B_d = 1.30(13) x 10-4 to be deduced for E(c.m.) > 200 keV. The
results provide the first unambiguous experimental evidence that the decay
takes place essentially in the halo of 11Li, and that it proceeds mainly to the
9Li + d continuum, opening up a new means to study of the halo wave function of
11Li.Comment: 4 pages, 3 figure
Study of bound states in 12Be through low-energy 11Be(d,p)-transfer reactions
The bound states of 12Be have been studied through a 11Be(d,p)12Be transfer
reaction experiment in inverse kinematics. A 2.8 MeV/u beam of 11Be was
produced using the REX-ISOLDE facility at CERN. The outgoing protons were
detected with the T-REX silicon detector array. The MINIBALL germanium array
was used to detect gamma rays from the excited states in 12Be. The gamma-ray
detection enabled a clear identification of the four known bound states in
12Be, and each of the states has been studied individually. Differential cross
sections over a large angular range have been extracted. Spectroscopic factors
for each of the states have been determined from DWBA calculations and have
been compared to previous experimental and theoretical results
Proton dripline studies at ISOLDE: Ar and C
In this contribution examples of the application of new technologies to disentangle the mechanism of -delayed multiparticle emission are given. In particular the mechanism of 2p-emission from Ar has been resolved and proved to be sequential, a preview of C-decay data is discussed
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