612 research outputs found
L'aula de noves tecnologies per a les ciències : aplicacions a l'ESO
La fĂsica i QuĂmica de 4t d'ESO ara es pot estudiar amb l'ajut d'una sèrie d'activitats disse-nyades per a ser realitzades amb l'aula de noves tecnologies per a les ciències. Les activi-tats consisteixen en protocols de prĂ ctiques per als alumnes, protocols amb suggeriments per als professors i presentacions PowerPoint associades a cada prĂ ctica. Hi ha onze acti-vitats. Es poden trobar a la web de l'autor en format pdf i word per tal que el professor pu-ga modificar-ho a voluntat
Optics Studies for Diffractive Physics at the LHC
Forward protons with momenta close to the beam-momentum arise either from elastic scattering or from single or double diffraction. These protons are very close to the beamline and can only be measured downstream using "beam close detectors". In this paper we present a complete study of the optics (low, medium and high beta), possible locations of the detectors and running scenarios for these measurements at insertions IR1 and IR5 of the LHC. These optics are compatible with the latest layout of the LHC insertions and the commissioning beam parameters
Non-expanding universe: a cosmological system of units
The product of two empirical constants, the dimensionless fine structure
constant and the von Klitzing constant (an electrical resistance), turns out to
be an exact dimensionless number. Then the accuracy and cosmological time
variation (if any) of these two constants are tied. Also this product defines a
natural unit of electrical resistance, the inverse of a quantum of conductance.
When the speed of light c is taken away from the fine structure constant, as
has been shown elsewhere, its constancy implies the constancy of the ratio e2/h
(the inverse of the von Klitzing constant), e the charge of the electron and h
Planck constant. This forces the charge of the electron e to be constant as
long as the action h (an angular momentum) is a true constant too. From the
constancy of the Rydberg constant the Compton wavelength, h/mc, is then a true
constant and consequently there is no expansion at the quantum mechanical
level. The momentum mc is also a true constant and then general relativity
predicts that the universe is not expanding, as shown elsewhere. The time
variation of the speed of light explains the observed Hubble red shift. And
there is a mass-boom effect. From this a coherent cosmological system of
constant units can be defined.Comment: 8 page
A Theory of time-varying Constants
We present a flat (K=0) cosmological model, described by a perfect fluid with
the ``constants'' and varying with cosmological time . We
introduce Planck\'s ``constant'' in the field equations through the
equation of state for the energy density of radiation. We then determine the
behaviour of the ``constants'' by using the zero divergence of the second
member of the modified Einstein\'s field equations i.e.
together with the
equation of state and the Einstein cosmological equations. Assuming realistic
physical and mathematical conditions we obtain a consistent result with . In this way we obtain gauge invariance for the Schr\"{o}dinger
equation and the behaviour of the remaining ``constants''Comment: 15 pages, RevTeX
Optimization of the e-e- option for the ILC
The e-e- running mode is one of the interesting physics options at the
International Linear Collider (ILC). The luminosity for e-e- collisions is
reduced by the beam-beam effects. The resulting beamstrahlung energy loss and
beam-beam deflection angles as function of the vertical transverse offset are
different compared to the e+e- collisions. In this paper, the dependence of
these observables with the offset for different beam sizes has been analyzed to
optimize performances for the e-e- mode, taking into account the requirements
of the beam-beam deflection based intra-train feedback system. A first study of
the implications for the final focus and extraction line optics is also
presented for the cases of the 20 mrad and 2 mrad ILC base line crossing angle
geometries
Precise measurement of the total cross section and the Coulomb scattering at the LHC
A precise measurement of the total cross section and the coulomb scattering
at the LHC requires the observation of elastically scatteredparticles at
extremely small angles (14 microrad, -t < 0.01 GeV**2 for the first case; 3
microrad, -t<0.0006 GeV**2 for the second one). In this paper a very high-beta
insertion optics is presented. A feasibility study, including the acceptance of
the detectors, for an experiment to be installed in IR1 or IR5, is also
presented.Comment: 3 pages, 4 figures, 7th European Particle Accelator Conferenc
The Speed of Light and the Hubble Parameter: The Mass-Boom Effect
We prove here that Newtons universal gravitation and momentum conservation
laws together reproduce Weinbergs relation. It is shown that the Hubble
parameter H must be built in this relation, or equivalently the age of the
Universe t. Using a wave-to-particle interaction technique we then prove that
the speed of light c decreases with cosmological time, and that c is
proportional to the Hubble parameter H. We see the expansion of the Universe as
a local effect due to the LAB value of the speed of light co taken as constant.
We present a generalized red shift law and find a predicted acceleration for
photons that agrees well with the result from Pioneer 10/11 anomalous
acceleration. We finally present a cosmological model coherent with the above
results that we call the Mass-Boom. It has a linear increase of mass m with
time as a result of the speed of light c linear decrease with time, and the
conservation of momentum mc. We obtain the baryonic mass parameter equal to the
curvature parameter, omega m = omega k, so that the model is of the type of the
Einstein static, closed, finite, spherical, unlimited, with zero cosmological
constant. This model is the cosmological view as seen by photons, neutrinos,
tachyons etc. in contrast with the local view, the LAB reference. Neither dark
matter nor dark energy is required by this model. With an initial constant
speed of light during a short time we get inflation (an exponential expansion).
This converts, during the inflation time, the Plancks fluctuation length of
10-33 cm to the present size of the Universe (about 1028 cm, constant from then
on). Thereafter the Mass-Boom takes care to bring the initial values of the
Universe (about 1015 gr) to the value at the present time of about 1055 gr.Comment: 15 pages, presented at the 9th Symposium on "Frontiers of Fundamental
Physics", 7-9 Jan. 2008, University of Udine, Italy. Changed content
Measurement of Driving Terms
In 2000 a series of MDs has been performed at the SPS to measure resonance driving terms. Theory predicts that these terms can be determined by harmonic analysis of BPM data recorded after applying single kicks at various amplitudes. Strong sextupoles were introduced to create a sizeable amount of nonlinearities. Experiments at injection energy (26 GeV) with single bunch as well as one experiment at 120 GeV with 84 bunches were carried out. The expected nonlinear content is compared to the experimenteal observation
Structure and Stability of 3He Droplets
We have studied the structure of 3He droplets at zero temperature using a density functional approach plus a configuration interaction calculation in an harmonic oscillator major shell. The most salient feature of open shell drops is that the valence atoms couple their spins to the maximum value compatible with Pauli's principle, building a large magnetic moment. We have determined that 29 atoms constitute the smallest self-bound droplet
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