The OPERA detector, designed to search for
ν
μ
→
ν
τ
oscillations in the CNGS beam, is located in the underground Gran Sasso laboratory, a privileged location to study TeV-scale cosmic rays. For the ...analysis here presented, the detector was used to measure the atmospheric muon charge ratio in the TeV region. OPERA collected charge-separated cosmic ray data between 2008 and 2012. More than 3 million atmospheric muon events were detected and reconstructed, among which about 110000 multiple muon bundles. The charge ratio
R
μ
≡
N
μ
+
/
N
μ
-
was measured separately for single and for multiple muon events. The analysis exploited the inversion of the magnet polarity which was performed on purpose during the 2012 Run. The combination of the two data sets with opposite magnet polarities allowed minimizing systematic uncertainties and reaching an accurate determination of the muon charge ratio. Data were fitted to obtain relevant parameters on the composition of primary cosmic rays and the associated kaon production in the forward fragmentation region. In the surface energy range 1–20 TeV investigated by OPERA,
R
μ
is well described by a parametric model including only pion and kaon contributions to the muon flux, showing no significant contribution of the prompt component. The energy independence supports the validity of Feynman scaling in the fragmentation region up to
200
TeV/nucleon primary energy.
This work is a study of the thermal behaviour of aluminium alloy 5754-H111 sheets welded with the friction stir welding (FSW) process. In particular, the feasibility of infrared thermography for ...monitoring of the FSW process is presented. This process has different advantages compared to those of traditional welding, such as very low welding temperature and low mechanical distortion. Usually in the literature, destructive tests are carried out to evaluate the quality of joints, but this approach is time-consuming and off-line. Results have shown that the thermal behaviour of joints is correlated to process parameters and that thermography can be used to perform the online monitoring of the FSW process.
Improving the detection efficiency in nuclear emulsion trackers Alexandrov, A.; Bozza, C.; Buonaura, A. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
03/2015, Letnik:
776
Journal Article
Recenzirano
Nuclear emulsion films are a tracking device with unique space resolution. Their use in nowadays large-scale experiments relies on the availability of automated microscope operating at very high ...speed. In this paper we describe the features and the latest improvements of the European Scanning System, a last-generation automated microscope for emulsion scanning. In particular, we present a new method for the recovery of tracking inefficiencies. Stacks of double coated emulsion films have been exposed to a 10GeV/c pion beam. Efficiencies as high as 98% have been achieved for minimum ionising particle tracks perpendicular to the emulsion films and of 93% for tracks with tan(θ)≃0.8.
Momentum measurement by the angular method in the Emulsion Cloud Chamber De Serio, M.; Ieva, M.; Simone, S. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
10/2003, Letnik:
512, Številka:
3
Journal Article
Recenzirano
Odprti dostop
We present the first automated momentum measurement in an Emulsion Cloud Chamber, consisting of multiple sandwiches of lead plates and nuclear emulsion sheets. The measurement is based on the ...detection of the multiple Coulomb scattering analysed by the so-called angular method. A 3
X
0 chamber was exposed to 2, 3 and
4
GeV/c
π
−. A pion momentum resolution of 36% at
4
GeV/c
, 35% at
3
GeV/c
and 28% for
2
GeV/c
was achieved.
Abstract
The standard model of particle physics currently provides our best description of fundamental particles and their interactions. The theory predicts that the different charged leptons, the ...electron, muon and tau, have identical electroweak interaction strengths. Previous measurements have shown that a wide range of particle decays are consistent with this principle of lepton universality. This article presents evidence for the breaking of lepton universality in beauty-quark decays, with a significance of 3.1 standard deviations, based on proton–proton collision data collected with the LHCb detector at CERN’s Large Hadron Collider. The measurements are of processes in which a beauty meson transforms into a strange meson with the emission of either an electron and a positron, or a muon and an antimuon. If confirmed by future measurements, this violation of lepton universality would imply physics beyond the standard model, such as a new fundamental interaction between quarks and leptons.
The PEANUT experiment was designed to study the NuMi neutrino beam at Fermilab. The detector uses a hybrid technique, being made of nuclear emulsions and scintillator trackers. Emulsion films act as ...a micrometric tracking device and are interleaved with lead plates used as passive material. The detector is designed to precisely reconstruct the topology of neutrino interactions and hence to measure the different contributions to the cross section. We present here the full reconstruction and analysis of 147 neutrino interactions and the measurement of the quasi-elastic, resonance and deep-inelastic contributions to the total charged current cross section at the energies of the NuMi neutrino beam. This technique could be applied for beam monitoring in future neutrino facilities, and this paper shows its proof-of-principle.
A fast automatic plate changer for the analysis of nuclear emulsions Balestra, S.; Bertolin, A.; Bozza, C. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
07/2013, Letnik:
716
Journal Article
Recenzirano
This paper describes the design and performance of a computer controlled emulsion Plate Changer for the automatic placement and removal of nuclear emulsion films for the European Scanning System ...microscopes. The Plate Changer is used for mass scanning and measurement of the emulsions of the OPERA neutrino oscillation experiment at the Gran Sasso lab on the CNGS neutrino beam. Unlike other systems it works with both dry and oil objectives. The film changing takes less than 20s and the accuracy on the positioning of the emulsion films is about 10μm. The final accuracy in retrieving track coordinates after fiducial marks measurement is better than 1μm.
The OPERA long-baseline neutrino experiment was exposed to the CNGS nu sub( mu ) beam from 2008 to 2012, collecting 19505 interactions in the target. The evidence for oscillated nu sub(tau) ...appearance, based on the observation of three nu sub(tau) 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 nu sub( mu ) arrow right nu sub(tau) oscillations is currently excluded at 4.2 sigma. 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 nu sub(tau) candidate event is presented and the significance of the observation is discussed.
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![Observation of [nu] sub( mu...](http://api.summon.serialssolutions.com/2.0.0/image/issn/XR4PS5YY4K/2100-014X/small "Observation of [nu] sub( mu ) arrow right [nu] sub([tau]) oscillations in the CNGS beam with the OPERA experiment")