1,142 research outputs found
Expression of the angular dependence of the quantum efficiency for a thin multi-alkali photocathode and its optical properties
The dependence of the quantum efficiency on the angle and polarization of the
incident photon needs to be formulated for a precise description of the
response of photomultiplier tubes. A simplified one-step model of photoelectron
emission was derived from Spicer's three-step model, and it enabled the
formulation of the dependence of the quantum efficiency in the visible range
for thin multi-alkali (NaKSbCs) photocathodes. The expression of the quantum
efficiency was proved by a measurement of the photocurrent for linearly
polarized light at various incident angles. Meanwhile, the measurement revealed
the complex refractive indices and thicknesses both of the stratified
photocathode and antireflection coating. It is indicated that the angular
dependence of the quantum efficiency is dictated by the optical properties of
the photocathode, which are discussed in detail on the basis of the obtained
parameters
Solenoid permits remote control of stop watch and assures restarting
Stop watch which may be remotely controlled by the use of a solenoid mechanism is described. When the solenoid is energized, the coil spring pulls the lever arm and starts the balance wheel. When it is not energized, the spring pulls the lever and stops the watch
Two types of well followed users in the followership networks of Twitter
In the Twitter blogosphere, the number of followers is probably the most
basic and succinct quantity for measuring popularity of users. However, the
number of followers can be manipulated in various ways; we can even buy
follows. Therefore, alternative popularity measures for Twitter users on the
basis of, for example, users' tweets and retweets, have been developed. In the
present work, we take a purely network approach to this fundamental question.
First, we find that two relatively distinct types of users possessing a large
number of followers exist, in particular for Japanese, Russian, and Korean
users among the seven language groups that we examined. A first type of user
follows a small number of other users. A second type of user follows
approximately the same number of other users as the number of follows that the
user receives. Then, we compare local (i.e., egocentric) followership networks
around the two types of users with many followers. We show that the second
type, which is presumably uninfluential users despite its large number of
followers, is characterized by high link reciprocity, a large number of friends
(i.e., those whom a user follows) for the followers, followers' high link
reciprocity, large clustering coefficient, large fraction of the second type of
users among the followers, and a small PageRank. Our network-based results
support that the number of followers used alone is a misleading measure of
user's popularity. We propose that the number of friends, which is simple to
measure, also helps us to assess the popularity of Twitter users.Comment: 4 Figures and 8 Table
Probing Models of Dirac Neutrino Masses via the Flavor Structure of the Mass Matrix
We classify models of the Dirac neutrino mass by concentrating on flavor
structures of the mass matrix. The advantage of our classification is that we
do not need to specify detail of models except for Yukawa interactions because
flavor structures can be given only by products of Yukawa matrices. All
possible Yukawa interactions between leptons (including the right-handed
neutrino) are taken into account by introducing appropriate scalar fields. We
also take into account the case with Yukawa interactions of leptons with the
dark matter candidate. Then, we see that flavor structures can be classified
into seven groups. The result is useful for the efficient test of models of the
neutrino mass. One of seven groups can be tested by measuring the absolute
neutrino mass. Other two can be tested by probing the violation of the lepton
universality in . In order to test the
other four groups, we can rely on searches for new scalar particles at collider
experiments.Comment: 21 pages, 20 eps files, published in PL
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