615 research outputs found
The Effect of Various Treatments on Microorganisms in the Soil under a Five-Year Rotation
It is generally conceded now that microorganisms play a large part in the transformations through which various plant food constituents pass, in the soil. They are the agents which are chiefly responsible for the production of available plant food. They break down organic matter, liberating the plant food constituents contained therein. The products of this decomposition react with the complex mineral soil constituents and change them into soluble, available compounds. Certain microorganisms also have the ability of utilizing the free nitrogen of the atmosphere, fixing it in the soil, to serve later for the feeding of plants
Ground state magnetic dipole moment of 35K
The ground state magnetic moment of 35K has been measured using the technique
of nuclear magnetic resonance on beta-emitting nuclei. The short-lived 35K
nuclei were produced following the reaction of a 36Ar primary beam of energy
150 MeV/nucleon incident on a Be target. The spin polarization of the 35K
nuclei produced at 2 degrees relative to the normal primary beam axis was
confirmed. Together with the mirror nucleus 35S, the measurement represents the
heaviest T = 3/2 mirror pair for which the spin expectation value has been
obtained. A linear behavior of gp vs. gn has been demonstrated for the T = 3/2
known mirror moments and the slope and intercept are consistent with the
previous analysis of T = 1/2 mirror pairs.Comment: 14 pages, 5 figure
Half-life and spin of 60Mn^g
A value of 0.28 +/- 0.02 s has been deduced for the half-life of the ground
state of 60Mn, in sharp contrast to the previously adopted value of 51 +/- 6 s.
Access to the low-spin 60Mn ground state was accomplished via beta decay of the
0+ 60Cr parent nuclide. New, low-energy states in 60Mn have been identified
from beta-delayed gamma-ray spectroscopy. The new, shorter half-life of 60Mn^g
is not suggestive of isospin forbidden beta decay, and new spin and parity
assignments of 1+ and 4+ have been adopted for the ground and isomeric
beta-decaying states, respectively, of 60Mn.Comment: 13 pages, 5 figures, Accepted for publication in Phys. Rev.
Probing shell structure and shape changes in neutron-rich sulfur isotopes through transient-field g factor measurements on fast radioactive beams of 38S and 40S
The shell structure underlying shape changes in neutron-rich nuclei near N=28
has been investigated by a novel application of the transient field technique
to measure the first-excited state g factors in 38S and 40S produced as fast
radioactive beams. There is a fine balance between proton and neutron
contributions to the magnetic moments in both nuclei. The g factor of deformed
40S does not resemble that of a conventional collective nucleus because spin
contributions are more important than usual.Comment: 10 pages, 6 figures, accepted in PR
Proton Drip-Line Calculations and the Rp-process
One-proton and two-proton separation energies are calculated for proton-rich
nuclei in the region . The method is based on Skyrme Hartree-Fock
calculations of Coulomb displacement energies of mirror nuclei in combination
with the experimental masses of the neutron-rich nuclei. The implications for
the proton drip line and the astrophysical rp-process are discussed. This is
done within the framework of a detailed analysis of the sensitivity of rp
process calculations in type I X-ray burst models on nuclear masses. We find
that the remaining mass uncertainties, in particular for some nuclei with
, still lead to large uncertainties in calculations of X-ray burst light
curves. Further experimental or theoretical improvements of nuclear mass data
are necessary before observed X-ray burst light curves can be used to obtain
quantitative constraints on ignition conditions and neutron star properties. We
identify a list of nuclei for which improved mass data would be most important.Comment: 20 pages, 9 figures, 2 table
Shell structure underlying the evolution of quadrupole collectivity in S-38 and S-40 probed by transient-field g-factor measurements on fast radioactive beams
The shell structure underlying shape changes in neutron-rich nuclei between
N=20 and N=28 has been investigated by a novel application of the transient
field technique to measure the first-excited state g factors in S-38 and S-40
produced as fast radioactive beams. Details of the new methodology are
presented. In both S-38 and S-40 there is a fine balance between the proton and
neutron contributions to the magnetic moments. Shell model calculations which
describe the level schemes and quadrupole properties of these nuclei also give
a satisfactory explanation of the g factors. In S-38 the g factor is extremely
sensitive to the occupation of the neutron p3/2 orbit above the N=28 shell gap
as occupation of this orbit strongly affects the proton configuration. The g
factor of deformed S-40 does not resemble that of a conventional collective
nucleus because spin contributions are more important than usual.Comment: 10 pages, 36 figures, accepted for publication in Physical Review
Half Life of the Doubly-magic r-Process Nucleus 78Ni
Nuclei with magic numbers serve as important benchmarks in nuclear theory. In
addition, neutron-rich nuclei play an important role in the astrophysical rapid
neutron-capture process (r-process). 78Ni is the only doubly-magic nucleus that
is also an important waiting point in the r-process, and serves as a major
bottleneck in the synthesis of heavier elements. The half-life of 78Ni has been
experimentally deduced for the first time at the Coupled Cyclotron Facility of
the National Superconducting Cyclotron Laboratory at Michigan State University,
and was found to be 110 (+100 -60) ms. In the same experiment, a first
half-life was deduced for 77Ni of 128 (+27 -33) ms, and more precise half-lives
were deduced for 75Ni and 76Ni of 344 (+20 -24) ms and 238 (+15 -18) ms
respectively.Comment: 4 pages, 3 figure
- …