3,081 research outputs found
Probing Nucleon Strangeness with Neutrinos: Nuclear Model Dependences
The extraction of the nucleon's strangeness axial charge, Delta_s, from
inclusive, quasielastic neutral current neutrino cross sections is studied
within the framework of the plane-wave impulse approximation. We find that the
value of Delta_s can depend significantly on the choice of nuclear model used
in analyzing the quasielastic cross section. This model-dependence may be
reduced by one order of magnitude when Delta_s is extracted from the ratio of
total proton to neutron yields. We apply this analysis to the interpretation of
low-energy neutrino cross sections and arrive at a nuclear theory uncertainty
of plus/minus 0.03 on the value of Delta_s expected to be determined from the
ratio of proton and neutron yields measured by the LSND collaboration. This
error compares favorably with estimates of the SU(3)-breaking uncertainty in
the value of Delta_s extracted from inclusive, polarized deep-inelastic
structure function measurements. We also point out several general features of
the quasielastic neutral current neutrino cross section and compare them with
the analogous features in inclusive, quasielastic electron scattering.Comment: 40 pages (including 11 postscript figures), uses REVTeX and
epsfig.st
The prevalence and distribution of the amyloidogenic transthyretin (TTR) V122I allele in Africa
Transthyretin (TTR) pV142I (rs76992529-A) is one of the 113 variants in the human TTR gene associated with systemic amyloidosis. It results from a G to A transition at a CG dinucleotide in the codon for amino acid 122 of the mature protein (TTR V122I). The allele frequency is 0.0173 in African Americans
Measuring Active-Sterile Neutrino Oscillations with a Stopped Pion Neutrino Source
The question of the existence of light sterile neutrinos is of great interest
in many areas of particle physics, astrophysics, and cosmology. Furthermore,
should the MiniBooNE experiment at Fermilab confirm the LSND oscillation
signal, then new measurements are required to identify the mechanism
responsible for these oscillations. Possibilities include sterile neutrinos, CP
or CPT violation, variable mass neutrinos, Lorentz violation, and extra
dimensions. In this paper, we consider an experiment at a stopped pion neutrino
source to determine if active-sterile neutrino oscillations with delta-m
greater than 0.1 eV2 can account for the signal. By exploiting stopped pi+
decay to produce a monoenergetic nu_mu source, and measuring the rate of the
neutral current reaction nu_x + 12C -> nu_x +12C* as a function of distance
from the source, we show that a convincing test for active-sterile neutrino
oscillations can be performed.Comment: 10 pages, 9 figure
Measurement of glucose exclusion from the fully hydrated DOPE inverse hexagonal phase
The degree of exclusion of glucose from the inverse hexagonal HII phase of fully hydrated DOPE is determined using contrast variation small angle neutron scattering and small angle X-ray scattering. The presence of glucose is found to favour the formation of the non-lamellar HII phase over the fluid lamellar phase, over a wide range of temperatures, while having no significant effect on the structure of the HII phase. Glucose is preferentially excluded from the lipid-water interface resulting in a glucose concentration in the HII phase of less than half that in the coexisting aqueous phase. The degree of exclusion is quantified and the results are consistent with a hydration layer of pure water adjacent to the lipid head groups from which glucose is excluded. The osmotic gradient created by the difference in glucose concentration is determined and the influence of glucose on the phase behaviour of non-lamellar phase forming lipid systems is discussed
Production and Decay of the Ge73-m Metastable State in a Low-Background Germanium Detector
The metastable states decay with a very characteristic signature
which allow them to be tagged event-by-event. Studies were performed using data
taken with a high-purity germanium detector in a low-background laboratory near
a nuclear power reactor core where \nuebar-flux was . The measured average and equilibrium production rates of
were and ,
respectively. The production channels were studied and identified. By studying
the difference in the production of between the reactor ON and OFF
spectra, the limiting sensitivities at the range of for the cross-sections of neutrino-induced nuclear
transitions were derived. The dominant background are due to -decays of
cosmic-ray induced Ga. The prospects of enhancing the sensitivities at
underground locations are discussed.Comment: 16 pages, 10 figure
A laser triggered electron source for pulsed radiolysis
We present the design of a photo-injector based accelerator for pulsed radiolysis applications. This machine is destined to meet the needs of the physical chemistry community at the Universite de Paris XI. A 4 MeV Energy electron pulse of a few picoseconds duration and with a charge in the range of 1 to 10 nC is produced from a Cs/sub 2 /Te photocathode. The photocathode is placed in the half energy spread cell of a 1-1/2 cell, 3 GHz RF gun, whose design is based on the gun used for the drive beam of the CERN CLIC Test facility. A 4 cell "booster" cavity is then used to accelerate the beam to an energy of 9 MeV. The transport system consists of a quadrupole triplet downsteam of the booster, two rectangular, 30 degree bend, dipoles with a pair of quadrupoles between them and a second triplet downstream of the second dipole. Energy dependent path length effects in the two dipoles allow the possibility of magnetic bunch compression depending on the phase-energy correlation of the bunch exiting the booster cavity. The beam envelope and the bunch length have been calculated through the transport line using TRACE-3d and PARMELA. These codes allow us to verify the required beam parameters at the experimental areas. We discuss the adjustment of the optics, aimed at producing the minimum electron bunch length at the experimental targets. (4 refs)
Quark-Gluon String Model Description of Baryon Production in K^{\pm}N Interactions
The process of baryon production in K p collisions at high energies is
considered in the framework of the Quark-Gluon String Model. The contribution
of the string-junction mechanism to the strange baryon production is analysed.
The results of numerical calculations are in reasonable agreement with the data
on inclusive spectra of p, Lambda, bar{Lambda}, and on the bar{Lambda}/Lambda
asymmetry. The predictions for Xi and Omega baryons are presented.Comment: 19 pages, 7 figure
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