239 research outputs found
Seasonal Moulting in Deer Mice (Peromyscus maniculatus) in the Rocky Mountains, Alberta
We recorded seasonal moulting in North American Deer Mice (Peromyscus maniculatus) in the Kananaskis River valley, Alberta, Canada, to test the hypothesis that moulting is restricted to the times of year that do not overlap with other high-energy demands, such as reproduction (spring and summer), or with low nutrient availability (winter). Although a seasonal trend showing a peak in moulting in the post-breeding period provided support for our prediction, a low level of continuous moulting did occur throughout the year
Branching ratios for the beta decay of 21Na
We have measured the beta-decay branching ratio for the transition from 21Na
to the first excited state of 21Ne. A recently published test of the standard
model, which was based on a measurement of the beta-nu correlation in the decay
of 21Na, depended on this branching ratio. However, until now only relatively
imprecise (and, in some cases, contradictory) values existed for it. Our new
result, 4.74(4)%, reduces but does not remove the reported discrepancy with the
standard model.Comment: Revtex4, 2 fig
Scattering of Be and B and the astrophysical S factor
Measurements of scattering of Be at 87 MeV on a melamine (CNH) target and of B at 95 MeV on C were performed. For Be
the angular range was extended over previous measurements and monitoring of the
intensity of the radioactive beam was improved. The measurements allowed us to
check and improve the optical model potentials used in the incoming and
outgoing channels for the analysis of existing data on the proton transfer
reaction N(Be,B)C. The resultslead to an updated
determination of the asymptotic normalization coefficient for the virtual decay
B Be + . We find a slightly larger value,
fm, for the melamine target. This
implies an astrophysical factor, eVb, for the
solar neutrino generating reaction Be(,)B.Comment: 7 pages, 4 figure
Experimental Validation of the Largest Calculated Isospin-Symmetry-Breaking Effect in a Superallowed Fermi Decay
A precision measurement of the gamma yields following the beta decay of 32Cl
has determined its isobaric analogue branch to be (22.47^{+0.21}_{-0.19})%.
Since it is an almost pure Fermi decay, we can also determine the amount of
isospin-symmetry breaking in this superallowed transition. We find a very large
value, delta_C=5.3(9)%, in agreement with a shell-model calculation. This
result sets a benchmark for isospin-symmetry-breaking calculations and lends
support for similarly-calculated, yet smaller, corrections that are currently
applied to 0+ -> 0+ transitions for tests of the Standard Model
Universal fluctuations in heavy-ion collisions in the Fermi energy domain
We discuss the scaling laws of both the charged fragments multiplicity
fluctuations and the charge of the largest fragment fluctuations for Xe+Sn
collisions in the range of bombarding energies between 25 MeV/A and 50 MeV/A.
We show close to E_{lab}=32 MeV/A the transition in the fluctuation regime of
the charge of the largest fragment which is compatible with the transition from
the ordered to disordered phase of excited nuclear matter. The size (charge) of
the largest fragment is closely related to the order parameter characterizing
this process.Comment: 4 pages, 3 figure
Probing the nuclear EOS with fragment production
We discuss fragmentation mechanisms and isospin transport occurring in
central collisions between neutron rich systems at Fermi energies. In
particular, isospin effects are analyzed looking at the correlations between
fragment isotopic content and kinematical properties. Simulations are based on
an approximate solution of the Boltzmann-Langevin (BL) equation. An attempt to
solve the complete BL equation, by introducing full fluctuations in phase space
is also discussed.Comment: 10 pages, 4 figures; Int.Nucl.Phys.Conf., Tokyo June 07, to appear in
Nucl.Phys.A (Elsart
Freeze-out volume in multifragmentation - dynamical simulations
Stochastic mean-field simulations for multifragmenting sources at the same
excitation energy per nucleon have been performed. The freeze-out volume, a
concept which needs to be precisely defined in this dynamical approach, was
shown to increase as a function of three parameters: freeze-out instant,
fragment multiplicity and system size.Comment: Submitted to Eur. Phys. J. A - march 200
Expanding RIB Capabilities at the Cyclotron Institute: \textsuperscript{3}He-LIG production with an Isobar Separator LSTAR
A new \textsuperscript{3}He-driven IGISOL production station and mass
separator have been designed to produce neutron-deficient low-mass isotopes at
the Cyclotron Institute for the TAMUTRAP facility. The LSTAR design has a mass
resolution to reject contaminants with
efficiency.Comment: Proceeding for EMIS 202
Measurement of the 20 and 90 keV resonances in the N reaction via THM
The reaction is of primary importance in
several astrophysical scenarios, including fluorine nucleosynthesis inside AGB
stars as well as oxygen and nitrogen isotopic ratios in meteorite grains. Thus
the indirect measurement of the low energy region of the reaction has been performed to reduce the nuclear
uncertainty on theoretical predictions. In particular the strength of the 20
and 90 keV resonances have been deduced and the change in the reaction rate
evaluated.Comment: 4 pages, 4 figures, submitted to PR
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