A study of stopping power in nuclear reactions at intermediate energies

We show a systematic experimental study based on INDRA data of the stopping power in central symmetric nuclear reactions. Total mass of the systems goes from 80 to 400 nucleons while the incident energy range is from 12 AMeV to 100 AMeV. The role of isospin diffusion at 32 and 45 MeV/nucleon with 124,136Xe projectiles on 112,124Sn targets performed at GANIL is also discussed. Results suggest a strong memory of the entrance channel above 20 AMeV/A (nuclear transparency) and, as such, constitute valuable tests of the microscopic transport models.Comment: 7 pages, 3 figures, Proceedings of International Workshop on Multifragmentation and Related Topics (IWM 2009), Catania, Italy, 4 Nov-7 Nov 200

Search for a Heavy Particle Decaying into an Electron and a Muon with the ATLAS Detector in √s = 7 TeV pp collisions at the LHC

This Letter presents the first search for a heavy particle decaying into an e^±μ^∓ final state in √s=7  TeV pp collisions at the LHC. The data were recorded by the ATLAS detector during 2010 and correspond to a total integrated luminosity of 35  pb^(-1). No excess above the standard model background expectation is observed. Exclusions at 95% confidence level are placed on two representative models. In an R-parity violating supersymmetric model, tau sneutrinos with a mass below 0.75 TeV are excluded, assuming all R-parity violating couplings are zero except λ'_(311)=0.11 and λ_(312)=0.07. In a lepton flavor violating model, a Z′-like vector boson with masses of 0.70–1.00 TeV and corresponding cross sections times branching ratios of 0.175–0.183 pb is excluded. These results extend to higher mass R-parity violating sneutrinos and lepton flavor violating Z’s than previous constraints from the Tevatron

Measurement of the Υ (1S) production cross-section in pp collisions at √s = 7 TeV in ATLAS

A measurement of the cross-section for Υ (1S)→μ^+μ^− production in proton–proton collisions at centre of mass energy of 7 TeV is presented. The cross-section is measured as a function of the Υ (1S) transverse momentum in two bins of rapidity, |y^(Υ(1S))| 4 GeV and pseudorapidity |η^μ| < 2.5 in order to reduce theoretical uncertainties on the acceptance, which depend on the poorly known polarisation. The results are based on an integrated luminosity of 1.13 pb^(−1), collected with the ATLAS detector at the Large Hadron Collider. The cross-section measurement is compared to theoretical predictions: it agrees to within a factor of two with a prediction based on the NRQCD model including colour-singlet and colour-octet matrix elements as implemented in Pythia while it disagrees by up to a factor of ten with the next-to-leading order prediction based on the colour-singlet model

Search for pair production of first or second generation leptoquarks in proton-proton collisions at √s = 7 TeV using the ATLAS detector at the LHC

This paper describes searches for the pair production of first or second generation scalar leptoquarks using 35  pb^(-1) of proton-proton collision data recorded by the ATLAS detector at √s=7  TeV. Leptoquarks are searched in events with two oppositely-charged muons or electrons and at least two jets, and in events with one muon or electron, missing transverse momentum and at least two jets. After event selection, the observed yields are consistent with the predicted backgrounds. Leptoquark production is excluded at the 95% CL for masses M_(LQ)<376 (319) GeV and M_(LQ)<422 (362) GeV for first and second generation scalar leptoquarks, respectively, when assuming the branching fraction of a leptoquark to a charged lepton is equal to 1.0 (0.5)

Limits on the production of the standard model Higgs boson in pp collisions at √s = 7 TeV with the ATLAS detector

A search for the Standard Model Higgs boson at the Large Hadron Collider (LHC) running at a centre-of-mass energy of 7 TeV is reported, based on a total integrated luminosity of up to 40 pb^(−1) collected by the ATLAS detector in 2010. Several Higgs boson decay channels: H→γγ, H→ZZ^((∗))→ℓℓℓℓ, H→ZZ→ℓℓνν, H→ZZ→ℓℓqq, H→WW^((∗))→ℓνℓν and H→WW→ℓνqq (ℓ is e, μ) are combined in a mass range from 110 GeV to 600 GeV. The highest sensitivity is achieved in the mass range between 160 GeV and 170 GeV, where the expected 95% CL exclusion sensitivity is at Higgs boson production cross sections 2.3 times the Standard Model prediction. Upper limits on the cross section for its production are determined. Models with a fourth generation of heavy leptons and quarks with Standard Model-like couplings to the Higgs boson are also investigated and are excluded at 95% CL for a Higgs boson mass in the range from 140 GeV to 185 GeV

Boron determination in steels by Inductively-Coupled Plasma spectometry (ICP)

The sample is treated with 5N H2SO4 followed by concentrated HNO3 and the diluted mixture is filtered. Soluble B is determined in the filtrate by Inductively-Coupled Plasma (ICP) spectrometry after addition HCl and extraction of Fe with ethyl-ether. The residue is fused with Na2CO3 and, after treatment with HCl, the insoluble B is determined by ICP spectrometry as before. The method permits determination of ppm amounts of B in steel