G. Zumerle

We report on a study of inclusive particle production in pp-interactions at 400 GeV/c. The data are based on 472 K reconstructed events recorded in the NA 27 experiment using the LEBC-EHS facility at CERN. The production cross sections are determined of pseudo scalar (π±,0, η andK ±), scalar (f 0(975)), vector (ρ±,0(770), ω(783), ϕ(1020),K *0(892), and $$\bar K^{ * 0} $$ (892)), and tensorf 0 mesons, of protons and antiprotons, and theΔ ++,+,0(1232), and Λ(1520) baryon resonances in the forward hemisphere of the center of mass system, as well as longitudinal and transverse momentum distributions. The results are compared with predictions of the FRITIOF model and with other experimental data.

The muon tomography technique, based on the Multiple Coulomb Scattering of cosmic ray muons, has been proposed recently as a tool to perform non-destructive assays of large-volume objects without any radiation hazard. In this paper we discuss experimental results obtained with a scanning system prototype, assembled using two large-area CMS Muon Barrel drift chambers. The capability of the apparatus to produce 3D images of objects and to classify them according to their density is presented. We show that the absorption of low-momentum muons in the scanned objects produces an underestimate of their scattering density, making the discrimination of materials heavier than lead more difficult.

A determination of branching ratios for D meson decays into all charged particle final states is reported. The values obtained: (D± → K∓π±π±/all D±) = (14 ± 6)% and (D0/D0 → K±π∓π+π−/all D0/D0) = (10 ± 4)%, are higher than those currently accepted. This result, if confirmed, implies a corresponding reduction in the accepted values for some total cross section measurements. Revised inclusive cross sections for D meson production in the forward hemisphere in π−p and pp interactions at 360 GeV/c, are presented.

The European Hybrid Spectrometer is described in its preliminary version for the NA16 charm experiment. The performance of the small hydrogen bubble chamber LEBC and the detectors of the spectrometer is discussed. In particular the combination of the bubble chamber information with the spectrometer data is described in detail. The track reconstruction efficiency is 90%. The precision with which vertices seen in the bubble chamber are reconstructed is around 10 μm and the two track resolution is 40 μm. Therefore very complex event configurations, in particular charm particle decays, can be reconstructed correctly.

In recent decades, muon imaging has found a plethora of applications in many fields. This technique succeeds to infer the density distribution of big inaccessible structures where conventional techniques cannot be used. The requirements of different applications demand specific implementations of image reconstruction algorithms for either multiple scattering or absorption-transmission data analysis, as well as noise-suppression filters and muon momentum estimators. This paper presents successful results of image reconstruction techniques applied to simulated data of some representative applications. In addition to well-known reconstruction methods, a novel approach, the so-called μCT, is proposed for the inspection of spent nuclear fuel canisters. Results obtained based on both μCT and the maximum-likelihood expectation maximization reconstruction algorithms are presented.This article is part of the Theo Murphy meeting issue 'Cosmic-ray muography'.

Results are presented on charm meson lifetimes. The sample of charm particle decays was obtained by exposing the high resolution rapid cycling hydrogen bubble chamber (LEBC) coupled with the European Hybrid Spectrometer to π− and p beams at 360 GeV/c ffrom the CERN SPS. The analysis of ∼850 k pictures has yielded 77 events containing a total of 60 charm decays. From these, an unbiased sample of 31 D decays (15± and 16 D0) is issued in the lifetime analysis. The measured mean lifetimes for D± and D0 are (where the symbol D0 means D0 and D0):τ(D±)=8.4+3.5−2.2 × 10−13sτ(D0)=4.1+1.3−0.9 ×10−13s. Three unambiguous examples of F± decay have also been observed and the corresponding lifetime, based on 2 decays, is τ(F±)=2.1 +3.6−0.8 × 10 −13s

We describe the two gamma detectors built for the European Hybrid Spectrometer (EHS). Their monitoring system is presented in detail. Results from tests and the performance obtained during the first EHS experiment are given.

Charm D-meson production in 360 GeV π−p interactions has been studied using the high-resolution hydrogen bubble chamber LEBC and the European Hybrid Spectrometer. The data show evidence for leading quark effects both in the number of D-meson types and in the Feynman x distributions. The production cross section is of the form d2δdxdpT2∞(1-x)nexp(-apT2) with n = 2.8±0.8 and a = 1.1±0.3 (GeV/c)−2. The x distribution is, however, compatible with the presence of both central (n = 6) and leading (n = 1) D/Dproduction. The fraction of D-messons in the leading component is estimated to be ≈30%. The rapidity gap between members of reconstructed charm pairs is small compared to the available rapidity range. The inclusive cross section for single D-messons in the forward direction is: δ(D/D)=(408+15)μb (forx>0).

Charm D-meson production in 360 GeV pp interactions has been studied using the high-resolution hydrogen bubble chamber LEBC and the European Hybrid Spectrometer. D-mesons are produced with a differential cross section of the form d2σdx dpT2δ(1-x)n exp (-apT2), withn=1.8± 0.8 and a=1.1±0.03 GeV/c−2 for the Feynman x and Transverse momentum pT behaviour. The inclusive partle prticle crossssection for D and D̄;measured to be: σ(D/D̄) = (56−12 25μb (for all x). The ΛcD̄ cross section can be estimated to be ≈20μb. No strong correlation is observed between DD̄ pairs. The results are compared with results from a study of D-meaon production in 360 GeV/c π−p interactions also using LEBC-EHS.

We demonstrate that muon tomography can be used to precisely measure the properties of various materials. The materials which have been considered have been extracted from an experimental blast furnace, including carbon (coke) and iron oxides, for which measurements of the linear scattering density relative to the mass density have been performed with an absolute precision of 10%. We report the procedures that are used in order to obtain such precision, and a discussion is presented to address the expected performance of the technique when applied to heavier materials. The results we obtain do not depend on the specific type of material considered and therefore they can be extended to any application.

Applications of cosmic-ray (CR) muons have grown in numbers in the last decade. Measurements of flux attenuation (radiography) and scattering angles (tomography) of CR muons have been successfully applied to the inspection or monitoring of large natural and civil structures, to the search for heavy metals in container and trucks, to the control of nuclear wastes, and much more. In the present work, a new Monte Carlo generator of CR muons, called EcoMug and specifically designed for muon radiography and tomography applications, is presented. It is a header-only C++11 library, based on a parametrization of experimental data. Unlike other tools, EcoMug gives the possibility of generating from different surfaces (plane, cylinder and half-sphere), while keeping the correct angular and momentum distribution of generated tracks. For example, this flexibility allows for a very efficient generation of nearly horizontal muons, of great interest in many muon radiography and tomography applications, by using cylindrical or half-spherical generation surfaces. Finally, EcoMug also allows the generation of CR muons according to user-defined parametrizations of their differential flux. Main features of EcoMug, its mathematical foundation, as well as applications to selected study cases are presented.

The muon tomography technique, based on multiple Coulomb scattering of cosmic ray muons, has been proposed as a tool to detect the presence of high density objects inside closed volumes. In this paper a new and innovative method is presented to handle the density fluctuations (noise) of reconstructed images, a well known problem of this technique. The effectiveness of our method is evaluated using experimental data obtained with a muon tomography prototype located at the Legnaro National Laboratories (LNL) of the Istituto Nazionale di Fisica Nucleare (INFN). The results reported in this paper, obtained with real cosmic ray data, show that with appropriate image filtering and muon momentum classification, the muon tomography technique can detect high density materials, such as lead, albeit surrounded by light or medium density material, in short times. A comparison with algorithms published in literature is also presented.

The 40 MHz bunched muon beam set up at CERN was used in May 2003 to make a full test of the drift tubes local muon trigger. The main goal of the test was to prove that the integration of the various devices located on a muon chamber was adequately done both on the hardware and software side of the system. Furthermore the test provided complete information about the general performance of the trigger algorithms in terms of efficiency and noise. Data were collected with the default configuration of the trigger devices and with several alternative configurations at various angles of incidence of the beam. Tests on noise suppression and di-muon trigger capability were performed.

Knowing the distribution of the materials in the blast furnace (BF) is believed to be of great interest for BF operation and process optimization. In this paper calibration samples (ferrous pellets and coke) and samples from LKAB’s experimental blast furnace (probe samples, excavation samples and core-drilling samples) were measured by the muon scattering tomography detector to explore the capability of using the muon scattering tomography to image the components in the blast furnace. The experimental results show that it is possible to use this technique to discriminate the ferrous pellets from the coke and it is also shown that the measured linear scattering densities (LSD) linearly correlate with the bulk densities of the measured materials. By applying the Stovall’s model a correlation among the LSD values, the bulk densities and the components of the materials in the probe samples and excavation samples was established. The theoretical analysis indicates that it is potential to use the present muon scattering tomography technique to image the components in various zones of the blast furnace.

A short description of the muon tomography demonstrator at the INFN Laboratori Nazionali di Legnaro near Padua, Italy, is given and the principal achievements owing to the data collected at that experimental facility are presented. In particular, the feasibility studies for several applications based on the muon-tomographic technology, within national and European projects, are discussed. The experimental problems and the procedures used to improve the performance are underlined. In addition, new activities and the related detector optimization are illustrated. This article is part of the Theo Murphy meeting issue ‘Cosmic-ray muography’.

The inclusive production of vector mesons (charged ρ(770), ω(783), ϕ(1020) and neutralK *(892)) in π− p interactions at 360 GeV/c is studied. The data are based on 160 000 reconstructed events recorded in the NA 27 Experiment using the LEBC-EHS facility at CERN. The production cross sections in the forward hemisphere in c.m.s. and the longitudinal momentum distributions are determined. The results are compared with data obtained at lower energies.

A prototype of the CMS Barrel Muon Detector incorporating all the features of the final chambers was built using the mass production assembly procedures and tools. The performance of this prototype was studied in a muon test beam at CERN and the results obtained are presented in this paper.

We present the performance of the DELPHI lead glass calorimeter with vacuum phototriode readout. The behaviour of the counters in magnetic fields up to 1.1 T is discussed. Experimental results, obtained with an electron beam from 7 to 50 GeV/c, on noise, linearity, energy and position resolution are presented.

In October 2001 the first produced CMS Barrel Drift Tube (DT) Muon Chamber was tested at the CERN Gamma Irradiation Facility (GIF) using a muon beam. A Resistive Plate Chamber (RPC) was attached to the top of the DT chamber, and, for the first time, both detectors were operated coupled together. The performance of the DT chamber was studied for several operating conditions, and for gamma rates similar to the ones expected at LHC. In this paper we present the data analysis; the results are considered fully satisfactory.

Muon tomography was recently proposed as a tool to inspect large volumes with the purpose of recognizing high density materials immersed in lower density matrices. The MU-STEEL European project (RFCS-CT-2010-000033) studied the application of such a technique to detect radioactive source shielding in truck containers filled with scrap metals entering steel mill foundries. A description of the muon tomography technique, of the MU-STEEL project and of the obtained results will be presented.

Bose-Einstein correlations among identically charged pions produced inpp collisions at 400 GeV/c are studied using the EHS spectrometer. Empoying the Kopylov-Podgoretskii parametrization, the average size of the emitting regionr k and its lifetime τ for pion production were determined to ber k=1.71±0.04 fm andcτ=0.89±0.05fm. The average sizer g in terms of the Lorentz invariant Goldhaber parametrization was determined to ber g=1.20±0.03fm. A decrease of the size with increasing momentum of the pions was observed. The size and the incoherence parameter of the pion emitting region were determined as a function of the charged particle multiplicity and the momentum of the pions. Identified charged kaons were used to study Bose-Einstein correlations among identically charged kaonsK ±K±. The average size of the emitting region for kaon production was determined to ber k=1.87±0.33fm in terms of the Kopylov-Podgoretskii parametrization. A study of the influence of a reference sample is presented.

Abstract The development of Saclay of scintillating fibers allows new compact structures for calorimetry. The construction of a prototype module designed and built at Saclay is described. It contains 3300 scintillating fibers regularly positioned and immersed in a low melting point BiPb alloy, giving a global radiation length of X 0 = 11.2 mm. Results of tests performed on an electron beam at DESY are presented and discussed. In addition, some ideas for industrial production are proposed.

Abstract The design and progress in the construction of the DELPHI microvertex detector are presented. The layout is described, together with results on precision mounting of silicon detectors. The development of ac-coupled silicon microstrip detectors was an important contribution to the design. The use of low-power CMOS readout chips facilitates the cooling of the detector. A description of the fourth-generation readout processor for silicon strip detectors, the SIROCCO IV, implemented in FASTBUS, is given. Finally, two complementary systems for in-situ position monitoring of the detectors are described.

The drift tube chambers developed for the muon barrel system of the CMS experiment at CERN are large area detectors with 8 measurement points in one direction and 4 in the other; each point has a resolution of about 200 mum. We are using two of such chambers for muon radiography, i.e. the detection and imaging of material with high atomic number Z through the measurement of the multiple scattering of cosmic- ray muons crossing the material itself. The chambers are self- triggered, using the trigger electronics developed for the CMS experiment. Such technique might be applied for example in cargo container inspection searching for high-Z materials. Our apparatus is composed by two chambers with a 7 m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> active area. In the gap between the chambers a container and the target material can be placed. Other two drift tube chambers, each with 4 measurement points, interleaved by a thick plane of Fe, give a rough determination of the cosmic muon momentum. We present results on the detection capability and performance of the system.

The accidental melting of radioactive sources hidden inside metal scrap containers can produce severe environmental harm. Modern melting facilities are equipped with portals measuring radiation levels. Nonetheless, sources can pass undiscovered when shielded inside shells of high density material, such as lead. From time to time indeed some radioactive sources pass undetected through the controls at foundries entrance. Once molten they caused enormous damages to the steel mills, contaminating all the production line. The muon tomography technique allows to discriminate high-Z materials measuring multiple scattering of cosmic ray muons inside matter. Therefore this technique can be used to analyse a truck container searching for high-density source shields. We report here the results about simulation studies of a muon tomography portal. Within the Mu-Steel European project we developed the prototype design, the three-dimensional images reconstruction software and the high density material identification algorithm. MonteCarlo simulation was validated with data from a large volume demonstrator (~11 m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> ) built using spare muon drift-time chambers of the CMS high energy physics experiment operating at the Large Hadron Collider at CERN.

The accidental melting of radioactive sources hidden inside metal scrap containers can produce severe environmental harm. Modern melting facilities are equipped with portals measuring radiation levels. Nonetheless, sources can pass undiscovered when shielded inside shells of high density material, such as lead. From time to time indeed some radioactive sources pass undetected through the controls at foundries entrance. Once melted they caused enormous damages to the steel mills, contaminating all the production line. The muon tomography technique allows to discriminate high- Z materials measuring multiple scattering of cosmic ray muons inside matter. Therefore this technique can be used to analyze a truck container searching for high-density source shields. We report here the results about simulation studies of a muon tomography portal. Within the Mu-Steel European project we developed the prototype design, the three-dimensional images reconstruction software and the high density material identification algorithm. MonteCarlo simulation was validated with data from a large volume demonstrator (~11 m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> ) built using spare muon drift-time chambers of the CMS high energy physics experiment operating at the Large Hadron Collider at CERN.

In this paper we describe the low noise electronic amplification chain designed for the readout of the one-stage vacuum photomultipiers (phototriodes) of the DELPHI lead-glass calorimeter. A mean open input electronic noise of 166 e− rms has been obtained with unipolar shaping. For completely mounted phototriodes in a situation very close to the final experimental setup and bipolar shaping we get a mean noise of 292 e− rms. Very good immunity against acoustic noise has been obtained. The gain stability during six months of operation is better than ±0.3%.

In an experiment with 360 GeV/cπ− beam at the CERN SPS using the high resolution hydrogen bubble chamber LEBC and the European Hybrid Spectrometer, an event has been observed of the type π−p→D0D0+ 8 prongs. The fully reconstructed decay modes are D0→K−π+π0π0andD0→K+π+π−π− , with all six charged tracks being detected in the spectrometer and all four photons from the π0 decays detected in the lead glass gamma detection system. The D0 has momentum 119.0 ± 0.6 GeV/c, xF = 0.31, length 4.1 ± 0.1 mm and proper lifetime (2.1 ± 0.1) × 10−13 s. The D0 has momentum 78.5 ± 0.3 GeV/c, xF = 0.19, length 7.5 ± 0.1 mm and proper lifetime (5.9 ± 0.1) × 10−13 s.

In a 2.5 events/μb exposure of a small 20 cm diameter, rapid cycling hydrogen bubble chamber equipped with high resolution optics, clear evidence is observed for the first time of the associated production of charmed particles, identified by their short decays. A significant excess of 12 events which we interpret as charm pairs corresponding to a total cross section of ∼ 40 μb is seen above the expected strange particle background. In addition, 8 charged 3 prong events consistent with D± decay are observed with an expected background of ∼ 2 events

Two drift tubes (DTs) chambers of the CMS muon barrel system were exposed to a 40 MHz bunched muon beam at the CERN SPS, and for the first time the whole CMS Level-1 DTs-based trigger system chain was tested. Data at different energies and inclination angles of the incident muon beam were collected, as well as data with and without an iron absorber placed between the two chambers, to simulate the electromagnetic shower development in CMS. Special data-taking runs were dedicated to test for the first time the Track Finder system, which reconstructs track trigger candidates by performing a proper matching of the muon segments delivered by the two chambers. The present paper describes the results of these measurements.

Cosmic rays are a constant, free source of radiation that can be exploited in various ways to probe heavy and extended objects. Analyzed with proper detection systems, they can produce radiographic as well as tomographic images of bulky materials. Several applications have been proposed, in particular in the domain of security checks, and some are presently fielded for routine use. In this paper, cosmic muon technology is presented, and its possible use in the field of cultural heritage is described. Les rayons cosmiques représentent une source constante et gratuite de radiation qui peut être utilisée de différentes façons pour sonder des objets massifs et volumineux. Analysés avec des systèmes de détection spécialisés, ils peuvent produire aussi bien des images radiographiques que des images tomographiques d'objets de grandes dimensions. De nombreuses applications ont été proposées, dont quelques-unes sont actuellement utilisées, notamment dans le domaine de la sécurité. Ce papier présente la technologie des muons cosmiques et décrit des utilisations possibles dans le domaine des biens culturels.

Abstract A prototype calorimeter of lead glass bars read by one-stage vacuum photomultipliers (triodes) has been tested at CERN with electrons in the energy range 2–30 GeV. Different glass-triode combinations have been compared. An electronic amplification noise corresponding to about 30 MeV has been obtained. The space resolution has been measured to be 4.4 mm on average.

Cosmic-ray radiation, thanks to its high penetration capability and relative abundance, has been successfully used in scientific research and civil applications for a long time.For example, techniques based on the attenuation of cosmic-ray muons (transmission muography) or on their angular scattering (scattering muography) have been used to study the inner structure of volcanoes, to search for hidden chambers in Egyptian pyramids, inspect nuclear waste containers, and monitor blast furnaces.In addition to these imaging techniques, cosmic-ray muons have also been used for the detector alignment in large experiments in nuclear and elementary particle physics and, more recently, proposed for the alignment and stability monitoring of mechanical structures.Transmission muography applications are sensitive to the angular distribution of cosmic muons, and many applications of scattering muography are also sensitive to their momentum distribution.For these reasons, an accurate simulation of the dependency of the muon flux on momentum and direction is a key requirement for every generation tool targeting such applications.Moreover, as the inspection of large structures requires a large number of cosmic-ray muons, the generator has also to be fast.A new Monte Carlo generator of cosmic-ray muons, called EcoMug (Efficient COsmic MUon Generator) and specifically designed for transmission and scattering applications, is presented.It is a header-only C++11 library, based on a specific parametrization of experimental data, but is easily replaceable by the user with a custom one.Unlike other tools, EcoMug gives the possibility of originating the cosmic-ray muons from different surfaces (plane, cylinder, and half-sphere), while keeping the correct angular and momentum distribution of generated tracks.The main features of EcoMug, its mathematical foundations, and applications to selected study cases are presented.

Abstract The barrel muon chambers of the CMS detector consist of three sets of four layers of rectangular drift tubes. The performance of several prototypes was measured in a muon beam for various experimental conditions. Special emphasis was given to study performance aspects related to the trigger capability of the chambers.

The drift tubes based CMS barrel muon trigger, which uses self-triggering arrays of drift tubes, is able to perform the identification of the muon parent bunch crossing using a rather sophisticated algorithm. The identification is unique only if the trigger chain is correctly synchronized. Some beam test time was devoted to take data useful to investigate the synchronization of the trigger electronics with the machine clock. Possible alternatives were verified and the dependence on muon track properties was studied.

A group at Saclay has conceived a new approach to the design of an electromagnetic shower calorimeter using scintillating fibers immersed in a low melting point high density alloy. The fibers point along the general direction of the showering particles. A (second) prototype was built using this principle and tested in a high energy electron beam (1 GeV to 25 GeV) at CERN. The test block measures 80 mm × 120 mm × 265 mm with a radiation length of X0 = 14.5 mm. The amount of light collected corresponds to 5000 photo electrons/GeV and is linear with energy between 1 and 25 GeV. The energy resolution was found to be σ/√E = (11 ± 2)% GeV12. The position resolution is of the order of 2 mm. An appreciable reduction from the block surface to the detecting p.m. surface is possible with very little loss of light. In a separate test we found that the clad fibers are considerably more resistant to radiation damage than the naked scintillator.

Two spare drift chambers produced for the barrel muon spectrometer of the LHC CMS experiment in I.N.F.N. Legnaro Laboratory (Padova, Italy) have been extensively tested using cosmic-ray events. A fitting algorithm was developed to infer in optimal way the t ime of passage of the particle, from which a timing resolution of 2 ns has been obtained. Using cosmic ray data, the algorithm allows to measure the track reconstruction precision of the chambers with the same accuracy as with high energy test beam data.

The drift chambers in the barrel region of the CMS detector are exposed to magnetic stray fields. To study the performance of the muon reconstruction and the drift time-based muon trigger, prototypes were tested under the expected magnetic field conditions at the H2 test facility at CERN. The results indicate that the overall chamber performance will not be affected. Only the bunch crossing identification capability in the small region near η=1.1, corresponding to the border of the solid angle region covered by the barrel, will be weakened.

Theπ 0 andη 0 production is studied inπ − p interactions at 360 GeV/c. The cross section forπ 0 production in the forward hemisphere (X>0) isσ(π 0)=(49.7 ± 1.0 ± 1.1) mb and for η withX>0.1,N ch>2,σ(η 0)=(3.1 ± 0.5) mb. The ratio of theπ 0 toη 0 cross section forX>0.1,N ch>2 isσ(π 0)/σ(η 0). Results on FeynmanX andp T distributions are presented. The data were obtained using the European Hybrid Spectrometer EHS and the bubble chamber LEBC at CERN.

We report on a study ofρ 0 andf 2 inclusive production in π−−p interactions at 360 GeV/c, using the LEBC-EHS set-up at CERN and reconstructing about 165000 events. Theρ 0,f 2 andρ 3 0 cross sections are determined forx F >0,x F >0.4 andx F >0.6 respectively and theρ 0 andf 2 Feynman-x distributions and transverse momentum distributions are presented.

Abstract A study of the length distribution of charged secondary interactions gives no evidence for the existence of charged anomalons in the products of the interactions of 360 GeV/ c π − and protons in hydrogen. Fits to the data yield 95% confidence level upper limits for anomalon production as a function of anomalon mean free path.

Cosmic ray radiation is mostly composed, at sea level, by high energy muons, which are highly penetrating particles capable of crossing kilometers of rock. Cosmic ray radiation constituted the first source of projectiles used to investigate the intimate structure of matter and is currently and largely used for particle detector test and calibration. The ubiquitous and steady presence at the Earth's surface and the high penetration capability has motivated the use of cosmic ray radiation also in fields beyond particle physics, from geological and archaeological studies to industrial applications and civil security. In the present paper, cosmic ray muon detection techniques are assessed for stability monitoring applications in the field of civil engineering, in particular for static monitoring of historical buildings, where conservation constraints are more severe and the time evolution of the deformation phenomena under study may be of the order of months or years. As a significant case study, the monitoring of the wooden vaulted roof of the "Palazzo della Loggia" in the town of Brescia, in Italy, has been considered. The feasibility as well as the performances and limitations of a monitoring system based on cosmic ray tracking, in the considered case, have been studied by Monte Carlo simulation and discussed in comparison with more traditional monitoring systems. Requirements for muon detectors suitable for this particular application, as well as the results of some preliminary tests on a muon detector prototype based on scintillating fibers and silicon photomultipliers SiPM are presented.

Three simplified prototypes of the first-level trigger front-end device for the muon barrel drift chambers of CMS were tested on a chamber prototype. Tests were performed at several incidence angles of a muon beam and with different magnetic field configurations. The recorded drift times were also used to test a full software model reproducing the actual algorithm applied in the final ASIC being produced. The efficiency performance of this software model and of the tested prototype are presented in this paper.

Abstract The performance of a small prototype chamber of the baseline project for the muon barrel detector for CMS has been studied in a muon beam. Its efficiency with different gases and wire diameters, the trigger possibilities and the response in presence of a large number of electromagnetic secondaries associated to the muon are evaluated. The results are compared with a full Monte Carlo simulation.

The contribution of the microstrip silicon vertex detector to the physics from the DELPHI experiment at LEP is presented. The tagging of quark flavour for Z0 decays to (dd, uu, ss), cc, bb, tt, and the spectroscopy of short-lived particles are the most natural initial physics goals for a vertex detector and provide a good introduction to more exotic physics investigations. Results of the Monte Carlo studies show the considerable improvement given by the vertex detector to these fields. The features important for the physics performance, such as detector geometry, measurement precision, alignment and pattern recognition, are discussed. Finally, some preliminary remarks concerning simple but efficient improvements of the detector geometry for the future are made.

Abstract Two modules will be used to digitize and store the signals of the DELPHI Forward Electromagnetic Calorimeter (FEMC): these are the ADC card and the Optical Receiver with Front-End Buffer unit (OFB). A description of these modules and their performance are presented.

Production of the muon barrel drift chambers called MB3 for the CMS experiment at the LHC has started at Legnaro INFN Labs in 2001. The detectors are fully equipped with the final front-end electronics and high-voltage boards, and test pulse and low-voltage systems. Before being moved to CERN, all chambers are tested and validated. After good noise level and proper high voltage behavior have been ensured, we collect cosmic-ray events triggered by an external scintillator system. We use those data to infer the main parameters of the chambers, namely, detection efficienc y, uniformity in behavior, timing properties (resolution, uniformity, dependence on track angle), and possible shifts of the wires and layers inside the superlayers. The method is particularly efficient in finding pathologies caused by trivial mistakes like, for example, an unconnected electrode, which can be quickly recovered.

Abstract A sample of ASIC prototypes of the first-level trigger front-end device for the muon barrel drift chambers of CMS was tested on a full size chamber prototype. Tests were performed at several incident angles on cosmic rays and at normal incidence using a muon beam. The chamber was irradiated using a 137 C s gamma source to simulate the LHC radiation environment. The performance of the tested prototypes with respect to efficiency, resolution and noise issues is reported.

A new Monte Carlo muon generator for cosmic-ray muon applications

The performance of an electromagnetic shower detector comprised only of active elements was evaluated using a tagged electron beam at various momenta from 30–100 GeV/c. Čerenkov light from three sections of lead glass blocks provides measurements of total shower energy with a resolution of σ = (0.114±0.008)EGeV/c2. A plastic scintillator hodoscope situated behind the first two lead glass layers samples the transverse development of the shower, allowing position determination of the incident electron with σ = 1.4 mm resolution.

Experimental tests are reported for the detection of the heavy metal shielding of orphan sources hidden inside scrap metal by using a recently developed muon tomography system. Shielded sources do not trigger alarm in radiation portal commonly employed at the entrance of steel industry using scrap metal. Future systems integrating radiation portals with muon tomography inspection gates will substantially reduce the possibility of accidental melting of radioactive sources securing the use of recycled metal.

Results on the longitudinal-momentum distributions of π±, K±, protons and antiprotons produced in 360 GeV/c π− interactions are presented. They are compared with other available data and discussed in terms of π− fragmentation.

Muon tomography has been recently proposed by a Los Alamos research group [1]. Some proponents of this abstract built and operated the first large volume prototype of muon tomography [2] and based on the results obtained participated to a request for European funding, that was granted in the Mu-Steel project [3]. The project started in July 2010 and finished at the end of 2012. The final goal of the project was the design of an inspection portal able to detect, using the cosmic rays, shielded radioactive sources hidden in scrap metal containers. Indeed in the last years it happened that such radioactive sources could pass undetected the entrance controls and, once melted, caused enormous damages to the steel mills, contaminating all the production line. The project studied and built a prototype for the muon detectors to be used in the portal, designed the structure and the configuration of the inspection portal and developed the needed tomographic reconstruction software. The results of the project will be presented and discussed.

We have measured 1320 events from the reaction pn→ π+π−π− at 2.98 GeV/c incident momentum (2.76 GeV total c.m. energy). The regular structure of zeros present in the three-pion Dalitz plot at lower energies is not found at this energy, except for a depopulation of events at m2(π+π1−) = m2(π+π2−) ⋍ 1.1 GeV2. The Dalitz plot population presents other structures which appear to be correlated with the angular variables describing the reaction.

The muon tomography technique, based on the Multiple Coulomb Scattering of cosmic ray muons, has been proposed recently as a tool to perform non-destructive assays of large-volume objects without any radiation hazard. In this paper we discuss experimental results obtained with a scanning system prototype, assembled using two large-area CMS Muon Barrel drift chambers. The capability of the apparatus to produce 3D images of objects and to classify them according to their density is presented. We show that the absorption of low-momentum muons in the scanned objects produces an underestimate of their scattering density, making the discrimination of materials heavier than lead more difficult.

We have made a transparent electromagnetic shower absorber, sandwiching together lead glass and scintillator sheets. The energy resolution we achieve is as good as expected for a sampling calorimeter with the passive layer thickness adopted, and the signal produced is about ten times larger than the signal from the Cherenkov radiation in the lead glass. We show that this makes possible the use of vacuum photodiodes with a noise level of the order of 40 MeV, and such a counter could therefore be operated in a magnetic field. Finally, we propose and discuss possible schemes for the production of large systems, arguing that the cost per counter would be significantly lower than an equivalent lead glass counter.

The non-linearity in the space-drift time relation of the DT drift cell, as a function of the track angle, has been measured using cosmic ray data. The improvement obtained in the track reconstruction precision is presented.

Author(s): Bettini, A.; Cresti, M.; Mazzucato, M.; Peruzzo, L.; Sartori, S.; Zumerle, G.; Alston-Garnjost, M.; Huesman, R.; Ross, R.; Soljaitz, F.F.; Bigi, A.; Carrara, R.; Casali, R.; Lariccia, P.; Pazzi, R.; Borreani, G; Quassiati, B.; Rinaudo, G.; Vigone, M.; Werbrouck, A.

The reaction pn → ppπ− at 2.98 GeV/c is studied with high statistics. The dominant Δ−− production is found in the framework of the additive quark model to proceed mainly through unnatural parity exchange in the t-channel. A detailed comparison with the reaction K−p → K∗0n confirms, for the dominant part of the cross section, the predictions of the quark model.

Examining lousely coupled parallel solutions as computing resource we found Local Area VAXcluster suitable for building a production Farm. We transformed, tuning LAVc parameters, a general purpose computing environment in a specialized one, optimized for the production needs. To face the higher complexity introduced by the subdivision of the production between several computers, we developed a central software structure that surveys the functioning of the farm, informs and interfaces the users, automatically closes productions, saves bookeeping information and reports errors. For this we needed an efficient process‐to‐process communication mechanism, that we found to be an innovative use of some Lock Management system features.

The interaction of high energy photons (or electrons) with matter gives rise to the phenomenon of multiplicative showers, used in the detectors called electromagnetic calorimeters to measure through complete absorption the energy of an incident particle. Cherenkov electromagnetic calorimeters measure the incident energy by means of the yield of Cherenkov light from the charged secondary particles in the shower. These detectors, widely used in high energy physics, provide in modern apparata a precise measurement of energy and position of the photons or electrons produced in the interaction. A detailed simulation of the development of electromagnetic showers and of the Cherenkov light propagation predicts an increase of the signal for lead-glass Cherenkov calorimeters in the presence of strong external magnetic fields. This increase is related to the Faraday effect on Cherenkov light, and can become sizeable in experimental conditions such as the typical ones in high energy physics.