Energy and angular distributions of X-ray synchrotron radiation produced by an ultra relativistic electron moving in a medium are discussed. Calculations show that the medium suppresses strongly the ...yield of the radiation for the electron Lorentz factor smaller than some cut-off value depending on the medium electron density and magnetic field applied.
The charge distribution of approximately 6000 nuclei with charge numbers above 55 in galactic cosmic rays has been obtained in the OLIMPIYA project. Three superheavy nuclei with the charge numbers in ...the range 105 <
Z
< 130 have been detected. The regression analysis has provided a more accurate estimate of the charge number of one of these nuclei (119
−6
+10
with a probability of 95%). Such nuclei should form stability islands. Their detection in nature confirms theoretical predictions and justifies efforts for their synthesis under terrestrial conditions. The model calculations performed in this work possibly can explain the results of some experiments on the investigation of the charge composition of cosmic rays in which particles with charge numbers in the range 94 <
Z
< 100 were detected (they cannot enter into the composition of primary cosmic radiation because their lifetime is very short). The calculations indicate that events with
Z
> 92 are due to the fragmentation of heavier nuclei from the stability island, rather than to methodical inaccuracies or fault of instruments. Several such events have been revealed. Thus, the track method makes it possible to obtain the results very important for understanding of the physical picture of the world. The results obtained within the OLIMPIYA project show that the study of tracks of galactic cosmic rays in olivine crystals from meteorites opens new capabilities for the investigation of fluxes and spectra in cosmic rays in the region of heavy and superheavy nuclei.
The OPERA experiment is based on a hybrid technology combining electronic detectors and nuclear emulsions. OPERA collected muon-neutrino interactions during the 2008 and 2009 physics runs of the CNGS ...neutrino beam, produced at CERN with an energy range of about 5-35 GeV. A total of $5.3 \times 10^{19}$ protons on target equivalent luminosity has been analysed with the OPERA electronic detectors: scintillator strips target trackers and magnetic muon spectrometers equipped with resistive plate gas chambers and drift tubes, allowing a detailed reconstruction of muon-neutrino interactions. Charged Current (CC) and Neutral Current (NC) interactions are identified, using the measurements in the electronic detectors, and the NC/CC ratio is computed. The momentum distribution and the charge of the muon tracks produced in CC interactions are analysed. Calorimetric measurements of the visible energy are performed for both the CC and NC samples. For CC events the Bjorken-$y$ distribution and the hadronic shower profile are computed. The results are compared to a detailed Monte Carlo simulation of the electronic detectors' response.
The NESSiE Collaboration has been setup to undertake a conclusive experiment to clarify the
muon-neutrino disappearance
measurements at short baselines in order to put severe constraints to models ...with more than the three-standard neutrinos. To this aim the current FNAL-Booster neutrino beam for a Short-Baseline experiment was carefully evaluated by considering the use of magnetic spectrometers at two sites, near and far ones. The detector locations were studied, together with the achievable performances of two OPERA-like spectrometers. The study was constrained by the availability of existing hardware and a time-schedule compatible with the undergoing project of multi-site Liquid–Argon detectors at FNAL. The settled physics case and the kind of proposed experiment on the Booster neutrino beam would definitively clarify the existing tension between the
ν
μ
disappearance and the
ν
e
appearance/disappearance at the eV mass scale. In the context of neutrino oscillations the measurement of
ν
μ
disappearance is a robust and fast approach to either reject or discover new neutrino states at the eV mass scale. We discuss an experimental program able to extend by more than one order of magnitude (for neutrino disappearance) and by almost one order of magnitude (for antineutrino disappearance) the present range of sensitivity for the mixing angle between standard and sterile neutrinos. These extensions are larger than those achieved in any other proposal presented so far.
The threshold-efficiency method for the detection of X-ray transition radiation in gas-filled proportional detectors
∼1
cm
thick is discussed. Analysis of experimental data obtained by this method ...shows that its separation factor is at least as good as that of the traditional method relying on truncated mean energy loss measurements. Arguments showing that the cluster counting method is based on a simplified consideration of the threshold-efficiency method are presented.
The OPERA detector at the Gran Sasso underground laboratory (LNGS) was used to measure the atmospheric muon charge ratio
in the TeV energy region. We analyzed 403069 atmospheric muons corresponding ...to 113.4 days of livetime during the 2008 CNGS run. We computed separately the muon charge ratio for single and for multiple muon events in order to select different energy regions of the primary cosmic ray spectrum and to test the
R
μ
dependence on the primary composition. The measured
R
μ
values were corrected taking into account the charge-misidentification errors. Data have also been grouped in five bins of the “vertical surface energy” ℰ
μ
cos
θ
. A fit to a simplified model of muon production in the atmosphere allowed the determination of the pion and kaon charge ratios weighted by the cosmic ray energy spectrum.
The results of measurements of the DD-reaction yields from the Ti/TiO
2
:D
x
heterostructure in the energy range of 10–25 keV are presented. Neutron and proton fluxes were measured using a neutron ...detector based on He-3 counters and a CR-39 plastic track detector. A comparison with calculations showed the existence of significant effects of DD-reaction yield amplification. The screening potential for this heterostructure under these experimental conditions was estimated to be in the range
U
e
= 160–750 eV.
The HARP detector at the CERN PS Catanesi, M.G.; Muciaccia, M.T.; Radicioni, E. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
02/2007, Letnik:
571, Številka:
3
Journal Article
Recenzirano
HARP is a high-statistics, large solid angle experiment to measure hadron production using proton and pion beams with momenta between 1.5 and 15
GeV/
c
impinging on many different solid and liquid ...targets from low to high
Z. The experiment, located in the T9 beam of the CERN PS, took data in 2001 and 2002. For the measurement of momenta of produced particles and for the identification of particle types, the experiment includes a large-angle spectrometer, based on a Time Projection Chamber and a system of Resistive Plate Chambers, and a forward spectrometer equipped with a set of large drift chambers, a threshold Cherenkov detector, a time-of-flight wall and an electromagnetic calorimeter. The large angle system uses a solenoidal magnet, while the forward spectrometer is based on a dipole magnet. Redundancy in particle identification has been sought, to enable the cross-calibration of efficiencies and to obtain a few percent overall accuracy in the cross-section measurements. Detector construction, operation and initial physics performances are reported. In addition, the full chain for data recording and analysis, from trigger to the software framework, is described.
Neutrino physics is nowadays receiving more and more attention as a possible source of information for the long–standing problem of new physics beyond the Standard Model. The recent measurement of ...the mixing angle θ13 in the standard mixing oscillation scenario encourages us to pursue the still missing results on leptonic CP violation and absolute neutrino masses. However, puzzling measurements exist that deserve an exhaustive evaluation.
The NESSiE Collaboration has been setup to undertake conclusive experiments to clarify the muon–neutrino disappearance measurements at small L/E, which will be able to put severe constraints to models with more than the three-standard neutrinos, or even to robustly measure the presence of a new kind of neutrino oscillation for the first time. To this aim the use of the current FNAL–Booster neutrino beam for a Short–Baseline experiment has been carefully evaluated. Its recent proposal refers to the use of magnetic spectrometers at two different sites, Near and Far ones. Their positions have been extensively studied, together with the possible performances of two OPERA–like spectrometers. The proposal is constrained by availability of existing hardware and a time–schedule compatible with the undergoing project of a multi–site Liquid–Argon detectors at FNAL.
The experiment to be possibly setup at Booster will allow to definitively clarify the current νμ disappearance tension with νe appearance and disappearance at the eV mass scale.
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