7 research outputs found
Time-resolved studies of emission properties of cerium-doped fluoro-hafnate glasses under VUV synchrotron radiation excitation
No full textDESIGN, CONSTRUCTION AND SIMULATION OF A UNIFORM MAGNETIC FIELD GENERATOR WITH STEEL NUCLEUS TO DEFLECT COSMIC RAYS
No full textAbstractA particle’s trajectory can be determined measuring some points where it has passed. This is applied to all kind of particles, including cosmic rays. In this paper we present the construction of a uniform magnetic field generator. Inside it, an arrangement of cosmic ray detectors will be placed in order to measure cosmic ray trajectories. We present details of the design, construction, calibration and some preliminary physical results.Keywords: Cosmic rays, helmholtz coils, relativistic particle, simulation.DISEÑO, CONSTRUCCIÓN Y SIMULACIÓN DE UN GENERADOR DE CAMPO MAGNÉTICO UNIFORME CON NÚCLEO DE ACERO PARA DEFLECTAR LOS RAYOS CÓSMICOSResumenLa trayectoria de una partícula puede ser determinada midiendo algunos puntos por los que ha pasado. Esto se aplica a cualquier tipo de partículas, incluyendo rayos cósmicos. En este se presenta la construcción de un generador de campo magnético uniforme, dentro del cual se colocará un arreglo de detectores para medir las trayectorias de los rayos cósmcios. Presentamos detalles del diseño, construcción, calibración y algunos resultados preliminaries.Palabras Claves: Bobinas, partícula relativista, rayos cósmicos, simulación
Measurement of single-spin azimuthal asymmetries in semi-inclusive electroproduction of pions and kaons on a longitudinally polarised deuterium target
No full textSingle-spin asymmetries have been measured for semi-inclusive electroproduction of pi /sup +/, pi /sup -/, pi /sup 0/ and K/sup +/ mesons in deep-inelastic scattering off a longitudinally polarised deuterium target. The asymmetries appear in the distribution of the hadrons in the azimuthal angle phi around the virtual photon direction, relative to the lepton scattering plane. The corresponding analysing powers in the sin phi moment of the cross section are 0.012+or-0.002(stat.)+or-0.002(syst.) for pi /sup +/, 0.006+or-0.003(stat.)+or-0.002(syst.) for pi /sup -/, 0.021+or-0.005(stat.)+or-0.003(syst.) for pi /sup 0/ and 0.013+or-0.006(stat.)+or-0.003(syst.) for K/sup +/ The sin 2 phi moments are compatible with zero for all particles
Hard exclusive electroproduction of π<sup>+</sup>π<sup>-</sup>pairs
No full textHard exclusive electroproduction of pi(+) pi(-) pairs off hydrogen and deuterium targets has been studied by the HERMES experiment at DESY Legendre moments (P-1) and (P-3) of the angular distributions of pi(+) mesons in the center-of-mass frame of the pair have been measured for the first time. Their dependence on the pi(+) pi(-) invariant mass can be understood as being due to the interference between relative P-wave (isovector) and S-, D-wave (isoscalar) states of the two pions. The increase in magnitude of (P-1) as Bjorken x increases is interpreted in the framework of generalized parton distributions as an enhancement of flavour non-singlet qq exchange for larger values of x, which leads to a sizable admixture of isoscalar and isovector pion pairs. In addition, the interference between P-wave and D-wave states separately for transverse and longitudinal pion pairs has been studied. The data indicate that in the f(2)(1270) region at [Q(2)] = 3 GeV2 higher-twist effects can be as large as the leading-twist longitudinal component
Evidence for a narrow |S|=1 baryon state at a mass of 1528 MeV in quasi-real photoproduction
No full textEvidence for a narrow baryon state is found in quasi-real photoproduction on a deuterium target through the decay channel pK(S)(0) → ppi(+)pi(-). A peak is observed in the pK(S)(0) invariant mass spectrum at 1528 +/- 2.6(stat) +/- 2.1(syst) MeV. Depending on the background model, the naive statistical significance of the peak is 4-6 standard deviations and its width may be somewhat larger than the experimental resolution of sigma = 4.3-6.2 MeV. This state may be interpreted as the predicted S = +1 exotic Theta(+)(uudd (s) over bar) pentaquark baryon. No signal for an hypothetical Theta(++) baryon was observed in the pK(+) invariant mass distribution. The absence of such a signal indicates that an isotensor Theta is excluded and an isovector Theta is unlikely
Measurement of the tensor structure function b(1) of the deuteron
No full textThe Hermes experiment has investigated the tensor spin structure of the deuteron using the 27.6GeV/c positron beam of DESY HERA. The use of a tensor-polarized deuteron gas target with only a negligible residual vector polarization enabled the first measurement of the tensor asymmetry Azzd and the tensor structure function b1d for average values of the Bjorken variable 0.01<x<0.45 and of the negative of the squared four-momentum transfer 0.5GeV2Q2<5GeV2. The quantities Azzd and b1d are found to be nonzero. The rise of b1d for decreasing values of x can be interpreted to originate from the same mechanism that leads to nuclear shadowing in unpolarized scattering. © 2005 The American Physical Society
