216 research outputs found
The OPERA experiment and its contribution to neutrino physics
The OPERA experiment has been running with the CNGS neutrino beam from 2008 to 2012 and collected 1.8 Ă 1020 protons on target. Five tau neutrino candidates were observed, with a background of 0.25 events, leading to the discovery of tau neutrino appearance in a muon neutrino beam, reported in 2015. The analysis of the emulsion films is now completed. We report preliminary results obtained with the analysis of the final sample. We also report a study on cosmic-ray annual modulation. We then give some final remarks including the near future plans of the Collaboration
Charm physics with the CHORUS experiment
High energy neutrino interactions induce charmed hadron production at the level of a few percent and therefore they constitute a powerful tool to study charm physics. The CHORUS experiment can profit of the extremely high spatial resolution of nuclear emulsions to identify and study the charm production and decay vertexes. This experiment is now analyzing the final data sample and publishing new results on the charm physics with the muon neutrino beam at CERN. In this paper we review these results in the general framework of charm physics with neutrinos
The SHiP experiment at CERN
The discovery of the Higgs boson has fully confirmed the Standard Model of particles and fields. Nevertheless, fundamental phenomena like the existence of dark matter and the baryon asymmetry of the Universe still deserve an explanation that could come from the discovery of new particles. The SHiP experiment proposal at CERN is meant to search for particles in the few GeV mass domain, very weakly coupled with ordinary particles. The existence of such particles, foreseen in Beyond Standard Models, is largely unexplored. A beam dump facility using high intensity 400 GeV protons is a copious source of such unknown particles in the GeV mass range. The beam dump is also a copious source of neutrinos and in particular it is an ideal source of tau neutrinos, the less known particle in the Standard Model. We report the physics potential of such an experiment. We also describe an ancillary measurement of the charm cross-section carried out in July 2018
Lossless Analog Compression
We establish the fundamental limits of lossless analog compression by
considering the recovery of arbitrary m-dimensional real random vectors x from
the noiseless linear measurements y=Ax with n x m measurement matrix A. Our
theory is inspired by the groundbreaking work of Wu and Verdu (2010) on almost
lossless analog compression, but applies to the nonasymptotic, i.e., fixed-m
case, and considers zero error probability. Specifically, our achievability
result states that, for almost all A, the random vector x can be recovered with
zero error probability provided that n > K(x), where K(x) is given by the
infimum of the lower modified Minkowski dimension over all support sets U of x.
We then particularize this achievability result to the class of s-rectifiable
random vectors as introduced in Koliander et al. (2016); these are random
vectors of absolutely continuous distribution---with respect to the
s-dimensional Hausdorff measure---supported on countable unions of
s-dimensional differentiable submanifolds of the m-dimensional real coordinate
space. Countable unions of differentiable submanifolds include essentially all
signal models used in the compressed sensing literature. Specifically, we prove
that, for almost all A, s-rectifiable random vectors x can be recovered with
zero error probability from n>s linear measurements. This threshold is,
however, found not to be tight as exemplified by the construction of an
s-rectifiable random vector that can be recovered with zero error probability
from n<s linear measurements. This leads us to the introduction of the new
class of s-analytic random vectors, which admit a strong converse in the sense
of n greater than or equal to s being necessary for recovery with probability
of error smaller than one. The central conceptual tools in the development of
our theory are geometric measure theory and the theory of real analytic
functions
Lossless Linear Analog Compression
We establish the fundamental limits of lossless linear analog compression by
considering the recovery of random vectors
from the noiseless linear
measurements
with
measurement matrix . Specifically,
for a random vector of arbitrary
distribution we show that can be recovered with
zero error probability from
linear measurements,
where denotes the lower
modified Minkowski dimension and the infimum is over all sets
with . This achievability statement holds for Lebesgue almost all measurement
matrices . We then show that -rectifiable random vectors---a
stochastic generalization of -sparse vectors---can be recovered with zero
error probability from linear measurements. From classical compressed
sensing theory we would expect to be necessary for successful
recovery of . Surprisingly, certain classes of
-rectifiable random vectors can be recovered from fewer than
measurements. Imposing an additional regularity condition on the distribution
of -rectifiable random vectors , we do get the
expected converse result of measurements being necessary. The resulting
class of random vectors appears to be new and will be referred to as
-analytic random vectors
Deep learning for Directional Dark Matter search
We provide an algorithm for detection of possible dark matter particle
interactions recorded within NEWSdm detector. The NEWSdm (Nuclear Emulsions for
WIMP Search directional measure) is an underground Direct detection Dark Matter
search experiment. The usage of recent developments in the nuclear emulsions
allows probing new regions in the WIMP parameter space. The directional
approach, which is the key feature of the NEWSdm experiment, gives the unique
chance of overcoming the "neutrino floor". Deep Neural Networks were used for
separation between potential DM signal and various classes of background. In
this paper, we present the usage of deep 3D Convolutional Neural Networks to
take into account the physical peculiarities of the datasets and report the
achievement of the required background rejection power.Comment: 5 pages, 6 figures. This is a proceedings paper from the ACAT2019
conference: https://indico.cern.ch/event/70804
Supernova neutrino physics with a nuclear emulsion detector
The existence of the coherent neutrino-nucleus scattering reaction requires
to evaluate, for any detector devoted to WIMP searches, the irreducible
background due to conventional neutrino sources and at same time, it gives a
unique chance to reveal supernova neutrinos. We report here a detailed study
concerning a new directional detector, based on the nuclear emulsion
technology. A Likelihood Ratio test shows that, in the first years of
operations and with a detector mass of several tens of tons, the observation of
the supernova signal can be achieved. The determination of the distance of the
supernova from the neutrinos and the observation of B neutrinos are also
discussed.Comment: 22 pages, 12 figure
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