Modelling the influence of shielding on physical and biological organ doses.

Distributions of "physical" and "biological" dose in different organs were calculated by coupling the FLUKA MC transport code with a geometrical human phantom inserted into a shielding box of variable shape, thickness and material. While the expression "physical dose" refers to the amount of deposited energy per unit mass (in Gy), "biological dose" was modelled with "Complex Lesions" (CL), clustered DNA strand breaks calculated in a previous work based on "event-by-event" track-structure simulations. The yields of complex lesions per cell and per unit dose were calculated for different radiation types and energies, and integrated into a version of FLUKA modified for this purpose, allowing us to estimate the effects of mixed fields. As an initial test simulation, the phantom was inserted into an aluminium parallelepiped and was isotropically irradiated with 500 MeV protons. Dose distributions were calculated for different values of the shielding thickness. The results were found to be organ-dependent. In most organs, with increasing shielding thickness the contribution of primary protons showed an initial flat region followed by a gradual decrease, whereas secondary particles showed an initial increase followed by a decrease at large thickness values. Secondary particles were found to provide a substantial contribution, especially to the biological dose. In particular, the decrease of their contribution occurred at larger depths than for primary protons. In addition, their contribution to biological dose was generally greater than that of primary protons

Modelling the radiation action for the estimation of biological effects in humans

It is well known that ionizing radiation can induce biological effects at different levels, from DNA, chromosomes and cells up to tissues, organs and entire organisms. Theoretical models and Monte Carlo codes, especially those based on radiation track structure, can be of great help to elucidate the underlying mechanisms and to perform reliable predictions where data are lacking. In this work we will present and discuss a mechanistic ab initio model and a Monte Carlo code able to simulate the induction of chromosome aberrations (CAs) in human cells. This endpoint is particularly relevant, since some aberration types can lead to cell death, while others can lead to cell conversion to malignancy. The model is based on the hypothesis that only clustered lesions (CLs) of the DNA double-helix can evolve into aberrations. Simulated dose-response curves for CAs induced by different radiation types (including heavy ions) will be shown, together with applications to cancer risk estimation and biodosimetry. In this framework, we will also discuss examples of medical applications - including astronauts' exposure to space radiation - obtained with the FLUKA code, also taking into account the role of nuclear interactions

Measurement of Through-Going Particle Momentum By Means Of Multiple Scattering With The ICARUS T600 TPC

The ICARUS collaboration has demonstrated, following the operation of a 600 ton (T600) detector at shallow depth, that the technique based on liquid Argon TPCs is now mature. The study of rare events, not contemplated in the Standard Model, can greatly benefit from the use of this kind of detectors. In particular, a deeper understanding of atmospheric neutrino properties will be obtained thanks to the unprecedented quality of the data ICARUS provides. However if we concentrate on the T600 performance, most of the $\nu_\mu$ charged current sample will be partially contained, due to the reduced dimensions of the detector. In this article, we address the problem of how well we can determine the kinematics of events having partially contained tracks. The analysis of a large sample of atmospheric muons collected during the T600 test run demonstrate that, in case the recorded track is at least one meter long, the muon momentum can be reconstructed by an algorithm that measures the Multiple Coulomb Scattering along the particle's path. Moreover, we show that momentum resolution can be improved by a factor two using an algorithm based on the Kalman Filtering technique

Measurement of the muon decay spectrum with the ICARUS liquid Argon TPC

Examples are given which prove the ICARUS detector quality through relevant physics measurements. We study the muon decay energy spectrum from a sample of stopping muon events acquired during the test run of the ICARUS T600 detector. This detector allows the spatial reconstruction of the events with fine granularity, hence, the precise measurement of the range and dE/dx of the muon with high sampling rate. This information is used to compute the calibration factors needed for the full calorimetric reconstruction of the events. The Michel rho parameter is then measured by comparison of the experimental and Monte Carlo simulated muon decay spectra, obtaining rho = 0.72 +/- 0.06(stat.) +/- 0.08(syst.). The energy resolution for electrons below ~50 MeV is finally extracted from the simulated sample, obtaining (Emeas-Emc)/Emc = 11%/sqrt(E[MeV]) + 2%.Comment: 16 pages, 8 figures, LaTex, A4. Some text and 1 figure added. Final version as accepted for publication in The European Physical Journal

Description and performance of MEA, The magnetic detector at adone

Abstract The experimental detector at Adone, MEA, which operates with its magnetic field perpendicular to the e + e − beams is described. Studies of the magnetic compensation for operation at Adone and resulting magnetic fields are presented. Particles are detected and analyzed using narrow-gap and wide-gap spark chambers which are triggered by scintillation and proportional counters. Momentum measurements for charged particles are made with Δ / p / p = ±0.07 at p = 1 Gev/ c ( B = 2.5 kG) and angles are measured to better than ± 1.5° over a solid angle of ∼0.3 × 4 π sr

The FLUKA Code: An Overview

FLUKA is a multipurpose Monte Carlo code which can transport a variety of particles over a wide energy range in complex geometries. The code is a joint project of INFN and CERN: part of its development is also supported by the University of Houston and NASA. FLUKA is successfully applied in several fields, including but not only, particle physics, cosmic ray physics, dosimetry, radioprotection, hadron therapy, space radiation, accelerator design and neutronics. The code is the standard tool used at CERN for dosimetry, radioprotection and beam-machine interaction studies. Here we give a glimpse into the code physics models with a particular emphasis to the hadronic and nuclear sector

Single hadron response measurement and calorimeter jet energy scale uncertainty with the ATLAS detector at the LHC

The uncertainty on the calorimeter energy response to jets of particles is derived for the ATLAS experiment at the Large Hadron Collider (LHC). First, the calorimeter response to single isolated charged hadrons is measured and compared to the Monte Carlo simulation using proton-proton collisions at centre-of-mass energies of sqrt(s) = 900 GeV and 7 TeV collected during 2009 and 2010. Then, using the decay of K_s and Lambda particles, the calorimeter response to specific types of particles (positively and negatively charged pions, protons, and anti-protons) is measured and compared to the Monte Carlo predictions. Finally, the jet energy scale uncertainty is determined by propagating the response uncertainty for single charged and neutral particles to jets. The response uncertainty is 2-5% for central isolated hadrons and 1-3% for the final calorimeter jet energy scale.Comment: 24 pages plus author list (36 pages total), 23 figures, 1 table, submitted to European Physical Journal

Search for squarks and gluinos in events with isolated leptons, jets and missing transverse momentum at s√=8 TeV with the ATLAS detector

The results of a search for supersymmetry in final states containing at least one isolated lepton (electron or muon), jets and large missing transverse momentum with the ATLAS detector at the Large Hadron Collider are reported. The search is based on proton-proton collision data at a centre-of-mass energy s√=8 TeV collected in 2012, corresponding to an integrated luminosity of 20 fb−1. No significant excess above the Standard Model expectation is observed. Limits are set on supersymmetric particle masses for various supersymmetric models. Depending on the model, the search excludes gluino masses up to 1.32 TeV and squark masses up to 840 GeV. Limits are also set on the parameters of a minimal universal extra dimension model, excluding a compactification radius of 1/R c = 950 GeV for a cut-off scale times radius (ΛR c) of approximately 30

Measurements of fiducial and differential cross sections for Higgs boson production in the diphoton decay channel at s√=8 TeV with ATLAS

Measurements of fiducial and differential cross sections are presented for Higgs boson production in proton-proton collisions at a centre-of-mass energy of s√=8 TeV. The analysis is performed in the H → γγ decay channel using 20.3 fb−1 of data recorded by the ATLAS experiment at the CERN Large Hadron Collider. The signal is extracted using a fit to the diphoton invariant mass spectrum assuming that the width of the resonance is much smaller than the experimental resolution. The signal yields are corrected for the effects of detector inefficiency and resolution. The pp → H → γγ fiducial cross section is measured to be 43.2 ±9.4(stat.) − 2.9 + 3.2 (syst.) ±1.2(lumi)fb for a Higgs boson of mass 125.4GeV decaying to two isolated photons that have transverse momentum greater than 35% and 25% of the diphoton invariant mass and each with absolute pseudorapidity less than 2.37. Four additional fiducial cross sections and two cross-section limits are presented in phase space regions that test the theoretical modelling of different Higgs boson production mechanisms, or are sensitive to physics beyond the Standard Model. Differential cross sections are also presented, as a function of variables related to the diphoton kinematics and the jet activity produced in the Higgs boson events. The observed spectra are statistically limited but broadly in line with the theoretical expectations

Measurement of χ c1 and χ c2 production with s√ = 7 TeV pp collisions at ATLAS

The prompt and non-prompt production cross-sections for the χ c1 and χ c2 charmonium states are measured in pp collisions at s√ = 7 TeV with the ATLAS detector at the LHC using 4.5 fb−1 of integrated luminosity. The χ c states are reconstructed through the radiative decay χ c → J/ψγ (with J/ψ → μ + μ −) where photons are reconstructed from γ → e + e − conversions. The production rate of the χ c2 state relative to the χ c1 state is measured for prompt and non-prompt χ c as a function of J/ψ transverse momentum. The prompt χ c cross-sections are combined with existing measurements of prompt J/ψ production to derive the fraction of prompt J/ψ produced in feed-down from χ c decays. The fractions of χ c1 and χ c2 produced in b-hadron decays are also measured