The NA62 experiment at the CERN SPS will measure the branching ratio for the decay K + → π + v - to within ≈10%. The large-angle veto (LAV) detectors must detect photons with energies as low as 200 ...MeV with an inefficiency of less than 10 -4 . After a comprehensive series of comparative studies, NA62 decided to base the LAV system on the lead-glass block/PMT assemblies recycled from the OPAL barrel calorimeter, and a prototype veto station, complete with front-end electronics, was constructed and tested in 2009. Eleven additional stations are to be constructed before data taking begins in 2012. We describe the design, construction, and testing of the LAV system, including the recovery and mechanical adaptation of the OPAL hardware, issues related to operation in high vacuum, HV distribution, and in-situ monitoring, and especially, the design of an efficient and economical system for the readout of time and energy over an extended dynamic range.
A measurement of the form factors of charged kaon semileptonic decays is presented, based on 4.4 × 106K± → π0e±νe (K e3 ± ) and 2.3 × 106K± → π0μ±νμ (K μ3 ±) decays collected in 2004 by the NA48/2 ...experiment. The results are obtained with improved precision as compared to earlier measurements. The combination of measurements in the K e3 ± and K μ3 ± modes is also presented.
The subject of space charge due to positive ions slowly moving in parallel plate ionization chambers is considered. A model for the degradation of the detector response is developed, with particular ...emphasis on electromagnetic calorimeters.The topics discussed include: (a) the stationary; (b) the time dependent cases; (c) the limit of very large space charge; (d) the electric field dependence of the electron drift velocity; (e) the effect of longitudinal development of showers; (f) the behaviour of the average reductions of response; (g) the non-uniformity of response for different positions of the shower axis inside the cell defined by the electrodes. The NA48 calorimeter is used as application and for comparison of results.
Abstract The NA48/2 experiment at CERN reports the first observation of the K ± → π 0 π 0 μ ± ν decay based on a sample of 2437 candidates with 15% background contamination collected in 2003–2004. ...The decay branching ratio in the kinematic region of the squared dilepton mass above 0.03 GeV2/c 4 is measured to be (0.65 ± 0.03) × 10 −6. The extrapolation to the full kinematic space, using a specific model, is found to be (3.45 ± 0.16) × 10 −6, in agreement with chiral perturbation theory predictions.
Recent QCD results from the NA48/2 experiment Anzivino, Giuseppina; Anzivino, G.; Arcidiacono, R. ...
Nuclear and particle physics proceedings,
07/2018, Letnik:
300-302
Journal Article
Recenzirano
The NA48/2 experiment collected data in 2003 and 2004 with the main purpose to study direct CP violation in charged kaons decaying in three pions. Thanks to the huge statistics collected, other ...studies are also possible. In this paper two recent results, in the framework of QCD studies, are reported: the measurement of the K± → π0e±ν Form Factors and the first observation of the rare decay K± → π±π0e+e−.
The NA62 experiment recorded a large sample of K+→μ+νμ decays in 2007. A peak search has been performed in the reconstructed missing mass spectrum. In the absence of a signal, limits in the range ...2×10−6 to 10−5 have been set on the squared mixing matrix element |Uμ4|2 between muon and heavy neutrino states, for heavy neutrino masses in the range 300–375 MeV/c2. The result extends the range of masses for which upper limits have been set on the value of |Uμ4|2 in previous production search experiments.
β-Thalassemia is an inherited disorder mainly caused by mutations in the gene of the β-globin chain of adult haemoglobin (HbA). Clinically, β-thalassemia can be a mild or silent condition, or it can ...cause severe diseases, leading to transfusion dependence. Studies at the gene level have identified a large number of variations in the β-globin gene in different populations. In the Mediterranean area one of the most common mutation is the C → T substitution in the codon 39 of the gene.
A new procedure for detecting codon 39 mutation in the β-globin gene is reported, based on a DNA piezoelectric biosensor. An oligonucletidic probe (25-mer), specific for the region around codon 39, is immobilised on the gold surface of a piezoelectric quartz crystal. The hybridisation between the immobilised probe and the complementary strand in solution is detected recording the variations of the crystal frequency.
Experiments with synthetic oligonucleotides were initially performed. Distinguishable frequency shifts were obtained from the interaction between the immobilised probe and the complementary and the mismatch oligonucleotides. A solution containing 50% of both the oligonucleotides has been also tested and distinguished from the others evaluating the resulting signals. Experiments with non-complementary oligonucleotides gave no signal variation. The biosensor was able to distinguish between sequences differing in only one base also using polymerase chain reaction-amplified samples 771 base pairs (bp) of DNA extracted from human blood of thalassemic and healthy (normal) patients or patients with β-thalassemia traits.
The optimised DNA piezoelectric biosensor has been successfully applied to the determination of one of the most frequent mutation characteristic of β-thalassemia in the Mediterranean population.
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