A
bstract
The OPERA experiment has discovered the tau neutrino appearance in the CNGS muon neutrino beam, in agreement with the 3 neutrino flavour oscillation hypothesis. The OPERA neutrino ...interaction target, made of Emulsion Cloud Chambers, was particularly efficient in the reconstruction of electromagnetic showers. Moreover, thanks to the very high granularity of the emulsion films, showers induced by electrons can be distinguished from those induced by
π
0
s, thus allowing the detection of charged current interactions of electron neutrinos. In this paper the results of the search for electron neutrino events using the full dataset are reported. An improved method for the electron neutrino energy estimation is exploited. Data are compatible with the 3 neutrino flavour mixing model expectations and are used to set limits on the oscillation parameters of the 3+1 neutrino mixing model, in which an additional mass eigenstate
m
4
is introduced. At high Δ
m
41
2
(≳0.1 eV
2
), an upper limit on sin
2
2
θ
μe
is set to 0.021 at 90% C.L. and Δ
m
41
2
≳ 4 × 10
− 3
eV
2
is excluded for maximal mixing in appearance mode.
A high resolution method to study the interface between two immiscible liquids is presented. The technique is based on the combination of a near-field optical probe and Raman spectroscopy. This ...combination brings together high local resolution in tip direction and the capability for molecular analysis at the interface. First
trans-phase boundary Raman profiles on the
p-xylene/ethylene glycol system measured with a spatial resolution of 1 μm are presented. Changes in the Raman bands due to the influence of the phase boundary extend as far as 10 μm from the phase boundary itself. Studies with coated and uncoated near-field probes demonstrate the important role of the optical near field in the experiments.
Measurements of the atmospheric flux of muons and other charged particles have been performed at the external site of the Gran Sasso Laboratory (LNGS, Italy,
1000
m
a.s.l.
), in view of the OPERA ...experiment. Scintillation counters and nuclear emulsion plates have been used. Rates and angular distributions at several depths of Fe shielding are presented and compared with Monte Carlo simulations.
A
bstract
The OPERA neutrino experiment is designed to perform the first observation of neutrino oscillations in direct appearance mode in the
ν
μ
→
ν
τ
channel, via the detection of the
τ
-leptons ...created in charged current ν
τ
interactions. The detector, located in the underground Gran Sasso Laboratory, consists of an emulsion/lead target with an average mass of about 1.2 kt, complemented by electronic detectors. It is exposed to the CERN Neutrinos to Gran Sasso beam, with a baseline of 730 km and a mean energy of 17 GeV. The observation of the first
ν
τ
candidate event and the analysis of the 2008-2009 neutrino sample have been reported in previous publications. This work describes substantial improvements in the analysis and in the evaluation of the detection efficiencies and backgrounds using new simulation tools. The analysis is extended to a sub-sample of 2010 and 2011 data, resulting from an electronic detector-based pre-selection, in which an additional
ν
τ
candidate has been observed. The significance of the two events in terms of a
ν
μ
→
ν
τ
oscillation signal is of 2.40
σ
.
A
bstract
A first result of the search for
ν
μ
→
ν
e
oscillations in the OPERA experiment, located at the Gran Sasso Underground Laboratory, is presented. The experiment looked for the appearance of
...ν
e
in the CNGS neutrino beam using the data collected in 2008 and 2009. Data are compatible with the non-oscillation hypothesis in the three-flavour mixing model. A further analysis of the same data constrains the non-standard oscillation parameters
θ
new
and
suggested by the LSND and MiniBooNE experiments. For large
values (
>
0.1 eV
2
), the OPERA 90% C.L. upper limit on sin
2
(2
θ
new
) based on a Bayesian statistical method reaches the value 7
.
2 × 10
−3
.
The OPERA long-baseline neutrino experiment was exposed to the CNGS νμ beam from 2008 to 2012, collecting 19505 interactions in the target. The evidence for oscillated ντ appearance, based on the ...observation of three ντ candidate events, has been previously reported. A fourth candidate event has been recently found in an extended data sample, corresponding to about 89% of the final statistics. The absence of a signal from νμ → ντ oscillations is currently excluded at 4.2σ. The status of the analysis is described in detail with special emphasis on the procedures applied for the selection of signal candidate events and the assessment of efficiencies and background. The fourth ντ candidate event is presented and the significance of the observation is discussed.
A
bstract
Heavy Neutral Leptons (HNLs) are hypothetical particles predicted by many extensions of the Standard Model. These particles can, among other things, explain the origin of neutrino masses, ...generate the observed matter-antimatter asymmetry in the Universe and provide a dark matter candidate.
The SHiP experiment will be able to search for HNLs produced in decays of heavy mesons and travelling distances ranging between
O
(50 m) and tens of kilometers before decaying. We present the sensitivity of the SHiP experiment to a number of HNL’s benchmark models and provide a way to calculate the SHiP’s sensitivity to HNLs for arbitrary patterns of flavour mixings. The corresponding tools and data files are also made publicly available.
In this paper a general cybernetic model has been developed to describe the growth of baker’s yeast in every type of reactor (batch, fed-batch, continuous). The model, which takes into account also ...the mass-transfer oxygen limitation, has been tested on literature continuous runs performed at different aerating gas composition. The results obtained show that the model can describe the growth of
S. cerevisiae also under conditions of inefficient aeration, so it should be useful to optimise and modeling industrial bioreactors.
Yeast growth is affected not only by the operative conditions (temperature, pH, sugar concentration) but also by the intrinsic properties of the investigated system, namely, type of strain, culture ...medium, and physiological state of the inoculum. Several authors describe the influence of the operative conditions quantitatively, whereas the effects of the intrinsic properties are in general reported as qualitative observations. In order to investigate these aspects, which are very important in the optimization of industrial baker's yeast production, several yeast growth runs were carried out varying the type of strain, the culture medium, and the physiological state of the inoculum employed. Experimental data on both batch and fed-batch baker's yeast growth were interpreted quantitatively using a modified and improved suitable cybernetic model. The results of a sensitivity analysis performed on the kinetic parameters of the model have shown that parameters related to the different culture medium and strain can be obtained by mathematical regression on experimental data. The parameters relating to the different physiological state of the inoculum are independent from strain and culture medium employed, so that one batch and one fed-batch growth run, carried out in defined operative conditions, are sufficient to determine the whole set of model parameters. Moreover, the improved model has been tested by simulating fed-batch growth runs, performed under different operative conditions, demonstrating its predictive power.
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