376 research outputs found
alpha-particle production in the scattering of 6He by 208Pb at energies around the Coulomb barrier
New experimental data from the scattering of 6He+208Pb at energies around and
below the Coulomb barrier are presented. The yield of breakup products coming
from projectile fragmentation is dominated by a strong group of
particles.
The energy and angular distributions of this group have been analyzed and
compared with theoretical calculations. This analysis indicates that the
particles emitted at backward angles in this reaction are mainly due
to two-neutron transfer to weakly bound states of the final nucleus.Comment: 20 pages, 5 figures. Nuclear Physics A792 (2007) 2-1
A Phase transition in acoustic propagation in 2D random liquid media
Acoustic wave propagation in liquid media containing many parallel air-filled
cylinders is considered. A self-consistent method is used to compute rigorously
the propagation, incorporating all orders of multiple scattering. It is shown
that under proper conditions, multiple scattering leads to a peculiar phase
transition in acoustic propagation. When the phase transition occurs, a
collective behavior of the cylinders appears and the acoustic waves are
confined in a region of space in the neighborhood of the transmission source. A
novel phase diagram is used to describe such phase transition.
Originally submitted on April 6, 99.Comment: 5 pages, 5 color figure
Tensor analyzing powers for 7 Li induced transfer breakup reactions
The T20 analyzing powers have been measured for the 12Sn(7Li ,8Be2a) 119In and 120Sn (7Li ,6Li*a+d) 121Sn transfer breakup reactions, using a 70 MeV beam. The data exhibit excellent agreement with the results of coupled reaction channels calculations, providing an important test of these calculations when applied to the transfer breakup reaction mechanism
Morphological, genetic and molecular characteristics of barley root hair mutants
Root hairs are tubular outgrowths of specialized
epidermal cells called trichoblasts. They affect anchoring plants
in soil, the uptake of water and nutrients and are the sites of the
interaction between plants and microorganisms. Nineteen root
hair mutants of barley representing different stages of root hair
development were subjected to detailed morphological and
genetic analyses. Each mutant was monogenic and recessive.
An allelism test revealed that nine loci were responsible for the
mutated root hair phenotypes in the collection and 1–4 mutated
allelic forms were identified at each locus. Genetic relationships
between the genes responsible for different stages of root
hair formation were established. The linkage groups of four loci
rhl1, rhp1, rhi1 and rhs1, which had previously been mapped
on chromosomes 7H, 1H, 6H and 5H, respectively, were
enriched with new markers that flank the genes at a distance
of 0.16 cM to 4.6 cM. The chromosomal position of three new
genes – two that are responsible for the development of short
root hairs (rhs2 and rhs3) and the gene that controls an irregular
root hair pattern (rhi2) – were mapped on chromosomes 6H,
2H and 1H, respectively. A comparative analysis of the
agrobotanical parameters between some mutants and their respective
parental lines showed that mutations in genes responsible
for root hair development had no effect on the
agrobotanical performance of plants that were grown under
controlled conditions. The presented mutant collection is a
valuable tool for further identification of genes controlling root
hair development in barley
Structure of unbound neutron-rich He studied using single-neutron transfer
The 8He(d,p) reaction was studied in inverse kinematics at 15.4A MeV using
the MUST2 Si-CsI array in order to shed light on the level structure of 9He.
The well known 16O(d,p)17O reaction, performed here in reverse kinematics, was
used as a test to validate the experimental methods. The 9He missing mass
spectrum was deduced from the kinetic energies and emission angles of the
recoiling protons. Several structures were observed above the neutron-emission
threshold and the angular distributions were used to deduce the multipolarity
of the transitions. This work confirms that the ground state of 9He is located
very close to the neutron threshold of 8He and supports the occurrence of
parity inversion in 9He.Comment: Exp\'erience GANIL/SPIRAL1/MUST
Gamma-Ray Spectroscopy of O and N Hypernuclei via the O reaction
he bound-state level structures of the O and
N hypernuclei were studied by -ray spectroscopy using
a germanium detector array (Hyperball) via the O ()
reaction. A level scheme for O was determined from the
observation of three -ray transitions from the doublet of states
(,) at MeV to the ground-state doublet (,). The
N hypernuclei were produced via proton emission from unbound
states in O . Three -rays were observed and the
lifetime of the state in N was measured by the
Doppler shift attenuation method. By comparing the experimental results with
shell-model calculations, the spin-dependence of the interaction is
discussed. In particular, the measured O ground-state doublet
spacing of 26.4 1.6 0.5 keV determines a small but nonzero strength
of the tensor interaction.Comment: 22 pages, 17 figure
Investigation of the 6He cluster structures
The 4He+2n and t+t clustering of the 6He ground state were investigated by
means of the transfer reaction 6He(p,t)4He at 25 MeV/nucleon. The experiment
was performed in inverse kinematics at GANIL with the SPEG spectrometer coupled
to the MUST array. Experimental data for the transfer reaction were analyzed by
a DWBA calculation including the two neutrons and the triton transfer. The
couplings to the 6He --> 4He + 2n breakup channels were taken into account with
a polarization potential deduced from a coupled-discretized-continuum channels
analysis of the 6He+1H elastic scattering measured at the same time. The
influence on the calculations of the 4He+t exit potential and of the triton
sequential transfer is discussed. The final calculation gives a spectroscopic
factor close to one for the 4He+2n configuration as expected. The spectroscopic
factor obtained for the t+t configuration is much smaller than the theoretical
predictions.Comment: 10 pages, 11 figures, accepted in PR
Colour-singlet strangelets at finite temperature
Considering massless and quarks, and massive (150 MeV) quarks in
a bag with the bag pressure constant MeV, a colour-singlet
grand canonical partition function is constructed for temperatures
MeV. Then the stability of finite size strangelets is studied minimizing the
free energy as a function of the radius of the bag. The colour-singlet
restriction has several profound effects when compared to colour unprojected
case: (1) Now bulk energy per baryon is increased by about MeV making the
strange quark matter unbound. (2) The shell structures are more pronounced
(deeper). (3) Positions of the shell closure are shifted to lower -values,
the first deepest one occuring at , famous -particle ! (4) The shell
structure at vanishes only at MeV, though for higher
-values it happens so at MeV.Comment: Revtex file(8 pages)+6 figures(ps files) available on request from
first Autho
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