805 research outputs found
Configurational Entropy can disentangle conventional hadrons from exotica
We evaluate the Configurational Entropy (CE) for scalar mesons and for
baryons in a holographic approach, varying the dimension of
boundary theory operators and using the soft-wall dual model of QCD. We find
that hybrid and multiquark mesons are characterized by an increasingly large
CE. A similar behavior is observed for baryons, where the
CE of pentaquarks is larger than for three-quark baryons, for same radial
number. Configurational Entropy seems relevant in disentangling conventional
hadrons from exotica.Comment: 13 pages, 4 figure
Unfolding spectral analysis of the Fermi-LAT data
The Large Area Telescope (LAT) onboard the Fermi satellite is observing the
gamma-ray sky in the high energy region, above 20 MeV. We have developed a
method to reconstruct the energy spectra of the gamma-rays detected by the
Fermi LAT instrument based on a Bayesian unfolding approach, that takes into
account the energy dispersion introduced by the instrument response. The method
has been successfully applied to reconstruct the energy spectra of both steady
and pulsating point sources. The analysis technique will be illustrated and the
results obtained in some significant test cases will be discussed.Comment: 6 pages, 9 figure
Measurement of the ratio h/e with a photomultiplier tube and a set of LEDs
We propose a laboratory experience aimed at undergraduate physics students to
understand the main features of the photoelectric effect and to perform a
measurement of the ratio h/e, where h is the Planck's constant and e is the
electron charge. The experience is based on the method developed by Millikan
for his measurements on the photoelectric effect in the years from 1912 to
1915. The experimental setup consists of a photomultiplier tube (PMT) equipped
with a voltage divider properly modified to set variable retarding potentials
between the photocathode and the first dynode, and a set of LEDs emitting at
different wavelengths. The photocathode is illuminated with the various LEDs
and, for each wavelength of the incident light, the output anode current is
measured as a function of the retarding potential applied between the cathode
and the first dynode. From each measurement, a value of the stopping potential
for the anode current is derived. Finally, the stopping potentials are plotted
as a function of the frequency of the incident light, and a linear fit is
performed. The slope and the intercept of the line allow respectively to
evaluate the ratio h/e and the ratio W/e, where W is the work function of the
photocathode.Comment: 14 pages, 4 figure
Measurements of the cosmic-ray electron and positron spectrum and anisotropies with the Fermi LAT
The Large Area Telescope (LAT) onboard the Fermi satellite is a pair-conversion telescope for high-energy gamma rays of astrophysical origin. Although it was designed to be a high-sensitivity gamma-ray telescope, the LAT has proved to be an excellent electron/positron detector. It has been operating in low Earth orbit since June 2008 and has collected more than 16 million cosmic-ray electron and positron (CRE) events in its first seven years of operation. The huge data sample collected by the LAT enables a precise measurement of the CRE energy spectrum up to the TeV region. A search for anisotropies in the arrival directions of CREs was also performed. The upper limits on the dipole anisotropy probe the presence of nearby young and middle-aged CRE sources
Hadronic interactions of primary cosmic rays with the FLUKA code
The measured fluxes of secondary particles produced by the interactions of
cosmic rays with the astronomical environment represent a powerful tool to
infer some properties of primary cosmic rays. In this work we investigate the
production of secondary particles in inelastic hadronic interactions between
several cosmic rays species of projectiles and different target nuclei of the
interstellar medium. The yields of secondary particles have been calculated
with the FLUKA simulation package, that provides with very good accuracy the
energy distributions of secondary products in a large energy range. An
application to the propagation and production of secondaries in the Galaxy is
presented.Comment: 8 pages, 4 figures; Contribution to the 34th International Cosmic Ray
Conference, July 30 to August 6, The Hague, Netherlands; fixing a typo in the
y-axis label of Fig.
A Bayesian approach to evaluate confidence intervals in counting experiments with background
In this paper we propose a procedure to evaluate Bayesian confidence
intervals in counting experiments where both signal and background fluctuations
are described by the Poisson statistics. The results obtained when the method
is applied to the calculation of upper limits will also be illustrated.Comment: 19 pages, 6 figure
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