Producción de semilla certificada de papa

El cultivo de la papa ha alcanzado gran importancia en el país en los últimos años, creemos que sea conveniente presentar una relación sobre las más comunes enfermedades y accidentes del cultivo y sobre los métodos que aquí o en otros países se están empleando para combatirlas. Esto parece aún más importante ahora, cuando estamos entrando en la fase de la producción de semilla certificada, para cuya organización y buen éxito es indispensable conocer a fondo y distinguir claramente los diversos tipos de enfermedades que atacan al cultivo

A Cost-Effective Design for a Neutrino Factory

There have been active efforts in the U.S., Europe, and Japan on the design of a Neutrino Factory. This type of facility produces intense beams of neutrinos from the decay of muons in a high energy storage ring. In the U.S., a second detailed Feasibility Study (FS2) for a Neutrino Factory was completed in 2001. Since that report was published, new ideas in bunching, cooling and acceleration of muon beams have been developed. We have incorporated these ideas into a new facility design, which we designate as Study 2B (ST2B), that should lead to significant cost savings over the FS2 design.Comment: 46 pages, 38 figures; to be submitted to Physical Review Special Topics: Accelerators and Beam

Paramaterizations of inclusive cross sections for pion production in proton-proton collisions. II. Comparison to new data

A set of new, precise data have recently been made available by the NA49 collaboration for charged pion production in proton-proton and proton-Carbon reactions at 158 GeV. The current paper compares this new data to five currently available arithmetic parameterizations. Although a precise fit is not expected, two of the parameterizations do not work very well but the other three are able to provide a moderately good, but not precise fit to the proton-proton data. The best two of these three parameterizations are scaled to the proton-Carbon data and again provide a moderately good, but not precise fit.Comment: 11 pages, 13 figures, Accepted for publication in Physical Review

Quadrupole deformation of deuterons and final state interaction in 2H⃗(e,e′p)^2 \vec H (e,e'p) scattering on tensor polarized deuterons at CEBAF energies

The strength of final state interaction (FSI) between struck proton and spectator neutron in $^2\vec{H}(e,e'p)$ scattering depends on the alignment of the deuteron. We study the resulting FSI effects in the tensor analyzing power in detail and find substantial FSI effects starting at still low missing momentum p_m \gsim 0.9 fm^{-1}. At larger p_m \gsim 1.5 fm^{-1}, FSI completely dominates both missing momentum distribution and tensor analyzing power. We find that to a large extent FSI masks the sensitivity of the tensor analyzing power to models of the deuteron wave function. For the transversely polarized deuterons the FSI induced forward-backward asymmetry of the missing momentum distribution is shown to have a node at precisely the same value of $p_m$ as the PWIA missing momentum distribution. The position of this node is not affected by FSI and can be a tool to distinguish experimentally between different models for the deuteron wave function.Comment: 24 pages, figures available from the authors on reques

Transverse spin dependence of pp total cross‐sections

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87331/2/72_1.pd

Semi-Inclusive Lambda and Kshort Production in p-Au Collisions at 17.5 GeV/c

The first detailed measurements of the centrality dependence of strangeness production in p-A collisions are presented. Lambda and Kshort dn/dy distributions from 17.5 GeV/c p-Au collisions are shown as a function of "grey" track multiplicity and the estimated number of collisions, nu, made by the proton. The nu dependence of the Lambda yield deviates from a scaling of p-p data by the number of participants, increasing faster than this scaling for nu<=5 and saturating for larger nu. A slower growth in Kshort multiplicity with nu is observed, consistent with a weaker nu dependence of K-Kbar production than Y-K production.Comment: 5 pages, 3 figures, formatted with RevTex, current version has enlarged figure catpion

Antiproton Production in p+Ap+A Collisions at AGS Energies

Inclusive and semi-inclusive measurements are presented for antiproton ($\bar{p}$) production in proton-nucleus collisions at the AGS. The inclusive yields per event increase strongly with increasing beam energy and decrease slightly with increasing target mass. The $\bar{p}$ yield in 17.5 GeV/c p+Au collisions decreases with grey track multiplicity, $N_g$, for $N_g>0$, consistent with annihilation within the target nucleus. The relationship between $N_g$ and the number of scatterings of the proton in the nucleus is used to estimate the $\bar{p}$ annihilation cross section in the nuclear medium. The resulting cross section is at least a factor of five smaller than the free $\bar{p}-p$ annihilation cross section when assuming a small or negligible formation time. Only with a long formation time can the data be described with the free $\bar{p}-p$ annihilation cross section.Comment: 8 pages, 6 figure

Physics at a Neutrino Factory

In response to the growing interest in building a Neutrino Factory to produce high intensity beams of electron- and muon-neutrinos and antineutrinos, in October 1999 the Fermilab Directorate initiated two six-month studies. The first study, organized by N. Holtkamp and D. Finley, was to investigate the technical feasibility of an intense neutrino source based on a muon storage ring. This design study has produced a report in which the basic conclusion is that a Neutrino Factory is technically feasible, although it requires an aggressive R&D program. The second study, which is the subject of this report, was to explore the physics potential of a Neutrino Factory as a function of the muon beam energy and intensity, and for oscillation physics, the potential as a function of baseline.Comment: 133 pages, 64 figures. Report to the Fermilab Directorate. Available from http://www.fnal.gov/projects/muon_collider/ This version fixes some printing problem