795 research outputs found
An algorithm for calculating the Lorentz angle in silicon detectors
Future experiments will use silicon sensors in the harsh radiation
environment of the LHC (Large Hadron Collider) and high magnetic fields. The
drift direction of the charge carriers is affected by the Lorentz force due to
the high magnetic field. Also the resulting radiation damage changes the
properties of the drift.
In this paper measurements of the Lorentz angle of electrons and holes before
and after irradiation are reviewed and compared with a simple algorithm to
compute the Lorentz angle.Comment: 13 pages, 7 figures, final version accepted by NIMA. Mainly
clarifications included and slightly shortene
Lorentz angle measurements in irradiated silicon detectors between 77 K and 300 K
Future experiments are using silicon detectors in a high radiation
environment and in high magnetic fields. The radiation tolerance of silicon
improves by cooling it to temperatures below 180 K. At low temperatures the
mobility increases, which leads to larger deflections of the charge carriers by
the Lorentz force. A good knowledge of the Lorentz angle is needed for design
and operation of silicon detectors. We present measurements of the Lorentz
angle between 77 K and 300 K before and after irradiation with a primary beam
of 21 MeV protons.Comment: 13 pages, 9 figures, submitted to ICHEP2000, Osaka, Japa
Facilitation of Ca 2+ -dependent exocytosis by Rac1-GTPase in bovine chromaffin cells
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/66111/1/jphysiol.2003.039073.pd
Consumer price indexes: an analysis of heterogeneity across sub-populations
La rilevanza dell'Indece dei Prezzi al Consumo quale misura dell'inflazione è stata a lungo dibattuta in particolare esminando le differenti cause di distorsione dovute all'utilizzo di un paniere fisso di beni e servizi. Di conseguenza la letteratura ha proposto indici dei prezzi sperimentali per particolari sottogruppi di popolazioni. tali indici hanno rilevanza ai fini della politica economica e sociale, poiché è probabile che differenti gruppi di popolazione abbiano comportamenti nei consumi differenti dalla media, ad esempio i consumatori poveri (Garner, Johnson & Kokoski, 1996) e quelli anziani (Stewart, 2008). Lo scopo di questo lavoro è quello di esaminare le possibilità offerte da metodi di costruzione alternativi degli Indici dei Prezzi al Consumo ai fini di cogliere la variabilità dei tassi di inflazione relativi a differenti categorie di consumatori.The soundeness of Consumer Price Indexes (CPI) as a measure of inflation has long been debeate, focusing on the different sources of bias inherent to use of a constant basket of goods and services. Thus experimental consumer price indexes have been proposed for targeted sub-populations specifically relevant for social and economic policy, that are likely to have consumption patterns different from yhe average, i.e poor (Garner, Johnson & Kokoski, 1996) and elderly (Stewart, 2008)houseolds. Aim of this work is to investigate the possibilities offered by alternative methods of construction of consumer price indices in order to capture the variability of inflation rates facing different houseolds' types
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Frequency bias in consumers' perceptions of inflation: An experimental study
We investigate whether the perception of economy-wide inflation is affected by the frequency with which various goods’ prices are observed. We provide novel experimental evidence that consumers’ perceptions of aggregate inflation are systematically biased toward the perceived inflation rates of the frequently purchased items. This ‘frequency bias’ may affect consumers’ consumption and investment decisions, and thus have important macroeconomic consequences. It may also explain why consumers typically over-estimate inflation in surveys during periods where frequently-purchased non-durable goods are inflating faster than durables
Study of Leading Hadrons in Gluon and Quark Fragmentation
The study of quark jets in e+e- reactions at LEP has demonstrated that the
hadronisation process is reproduced well by the Lund string model. However, our
understanding of gluon fragmentation is less complete. In this study enriched
quark and gluon jet samples of different purities are selected in three-jet
events from hadronic decays of the Z collected by the DELPHI experiment in the
LEP runs during 1994 and 1995. The leading systems of the two kinds of jets are
defined by requiring a rapidity gap and their sum of charges is studied. An
excess of leading systems with total charge zero is found for gluon jets in all
cases, when compared to Monte Carlo Simulations with JETSET (with and without
Bose-Einstein correlations included) and ARIADNE. The corresponding leading
systems of quark jets do not exhibit such an excess. The influence of the gap
size and of the gluon purity on the effect is studied and a concentration of
the excess of neutral leading systems at low invariant masses (<~ 2 GeV/c^2) is
observed, indicating that gluon jets might have an additional hitherto
undetected fragmentation mode via a two-gluon system. This could be an
indication of a possible production of gluonic states as predicted by QCD.Comment: 19 pages, 6 figures, Accepted by Phys. Lett.
Determination of the b quark mass at the M_Z scale with the DELPHI detector at LEP
An experimental study of the normalized three-jet rate of b quark events with
respect to light quarks events (light= \ell \equiv u,d,s) has been performed
using the CAMBRIDGE and DURHAM jet algorithms. The data used were collected by
the DELPHI experiment at LEP on the Z peak from 1994 to 2000. The results are
found to agree with theoretical predictions treating mass corrections at
next-to-leading order. Measurements of the b quark mass have also been
performed for both the b pole mass: M_b and the b running mass: m_b(M_Z). Data
are found to be better described when using the running mass. The measurement
yields: m_b(M_Z) = 2.85 +/- 0.18 (stat) +/- 0.13 (exp) +/- 0.19 (had) +/- 0.12
(theo) GeV/c^2 for the CAMBRIDGE algorithm. This result is the most precise
measurement of the b mass derived from a high energy process. When compared to
other b mass determinations by experiments at lower energy scales, this value
agrees with the prediction of Quantum Chromodynamics for the energy evolution
of the running mass. The mass measurement is equivalent to a test of the
flavour independence of the strong coupling constant with an accuracy of 7
permil.Comment: 24 pages, 10 figures, Accepted by Eur. Phys. J.
Measurement and Interpretation of Fermion-Pair Production at LEP energies above the Z Resonance
This paper presents DELPHI measurements and interpretations of
cross-sections, forward-backward asymmetries, and angular distributions, for
the e+e- -> ffbar process for centre-of-mass energies above the Z resonance,
from sqrt(s) ~ 130 - 207 GeV at the LEP collider. The measurements are
consistent with the predictions of the Standard Model and are used to study a
variety of models including the S-Matrix ansatz for e+e- -> ffbar scattering
and several models which include physics beyond the Standard Model: the
exchange of Z' bosons, contact interactions between fermions, the exchange of
gravitons in large extra dimensions and the exchange of sneutrino in R-parity
violating supersymmetry.Comment: 79 pages, 16 figures, Accepted by Eur. Phys. J.
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