C. Sciacca

The design and operation of precision drift chambers with multisampling as well as the concepts and methods for reaching an extraordinary degree of precision in mechanics and calibration are described. Specific instruments were developed for this purpose. The concept of reproducible positioning and the implementation to 30 μm accuracy, showing stability over three years, is given. Calibration and analysis with UV-laser and cosmic test measurements are outlined with the critical results. The experience of calibration and reliability of the large system in an actual L3 running experiment is analyzed. The resolution under “battle conditions” at LEP resulted in Δpp = (2.50±0.04)% at 45.6 GeV and will be presented in detail. The concept is well suited for future TeV energies.

The CMS Barrel resistive plate chambers quality tests are performed at three different sites (Bari, Pavia and Sofia), where equivalent software and hardware tools are used. Data from the first 210 detectors are available for a comprehensive analysis. The paper describes the general experimental set-up, the test procedure and the cosmic muon test results. The muon trajectory reconstruction algorithm, used for precise studies, is presented. The criteria to accept or reject a detector are also given. The CMS final-design chambers show an average efficiency greater than 95%.

The formation of highly reactive compounds in the gas mixture during Resistive Plate Chambers (RPCs) operation at the CERN Gamma Irradiation Facility (GIF) is studied. Results from two different types of chambers are discussed: 50 × 50 cm2 RPC prototypes and two final CMS-RB1 chambers. The RB1 detectors were also connected to a closed loop gas system. Gas composition, possible additional impurities as well as fluoride ions have been monitored in different gamma irradiation conditions both in open and closed loop mode. The chemical composition of the RPC electrode surface has also been analyzed using an electron microscope equipped with an EDS/X-ray.

The SuperB project is an asymmetric e+e− accelerator of 1036cm−2s−1 design luminosity, capable of collecting a data sample of 50–75ab−1 in five years running. The SuperB electromagnetic calorimeter (EMC) provides energy and direction measurement of photons and electrons, and is used for identification of electrons versus other charged particles. In particular we present its design, geometry study and related simulations, as well as R&D on LYSO crystals and developments on readout electronics. A matrix of 25 crystals has been tested at the Beam Test Facility of Frascati (BTF) in May 2011 at energies between 200 MeV and 500 MeV. Results from this test are presented.

The status of the CMS RPC Gas Gain Monitoring (GGM) system developed at the Frascati Laboratory of INFN (Istituto Nazionale di Fisica Nucleare) is reported on. The GGM system is a cosmic ray telescope based on small RPC detectors operated with the same gas mixture used by the CMS RPC system. The GGM gain and efficiency are continuously monitored on-line, thus providing a fast and accurate determination of any shift in working point conditions. The construction details and the first result of GGM commissioning are described.

Several small single gap Resistive Plate Chambers and two RB1 CMS final stations have been exposed during the last year at the CERN Gamma Irradiation Facility to study possible long-term ageing effects. Up to now, an integrated charge of about 0.05C/(cm2gap) and 0.025 C/(cm2 gap) has been accumulated for the small RPCs and the large RB1 stations, respectively. Current, rate, fast charge and efficiency have been continuously monitored with muon beam or cosmics. Results concerning operation with a moisty mixture are also reported.

The BaBar experiment at PEPII relies on the instrumentation of the flux return (IFR) for both muon identification and KL detection. The active detector is composed of resistive plate chambers (RPCs) operated in streamer mode. Since the start of operation the RPCs have suffered persistent efficiency deterioration and dark current increase problems. The “autopsy” of bad BaBar RPCs revealed that in many cases uncured linseed oil droplets had formed on the inner surface of the Bakelite plates, leading to current paths from oil “stalagmites” bridging the 2 mm gap. In this paper, a possible model of this “stalagmite” formation and its effect on the dark current and efficiency of RPC chambers is presented. Laboratory test results strongly support this model. Based upon this model we are searching for solutions to eliminate the unfavorable effect of the oil stalagmites. The lab tests show that the stalagmite resistivity increases dramatically if exposed to the air, an observation that points to a possible way to remedy the damage and increase the efficiency. We have seen that flowing an oxygen gas mixture into the chamber helps to polymerize the uncured linseed oil. Consequently, the resistivity of the bridged oil stalagmites increases, as does that of the oil coating on the frame edges and spacers, significantly reducing the RPC dark currents and low-efficiency regions. We have tested this idea on two chambers removed from BaBar because of their low efficiency and high dark current. These test results are reported in the paper, and two other remediation methods also mentioned. We continue to study this problem, and try to find new treatments with permanent improvement.

The formation of reactive compounds in the gas mixture during Resistive Plate Chambers (RPCs) operation at the CERN Gamma Irradiation Facility (GIF) is studied. Results from two different types of chambers are discussed: 50×50cm2 RPC prototypes and two final CMS-RB1 chambers. The RB1 detectors were also connected to a closed loop gas system. Gas composition and possible additional impurities have been monitored in different gamma irradiation conditions both in open and closed loop modes using a gas chromatograph. Dedicated measurements for fluoride concentration in the exhausted gas line were performed at different irradiations and operation conditions using a specific electrode and a High-Performance Liquid Chromatograph. The efficiency of the purifiers system present in the closed loop in removing the F- and others impurities has also been investigated. Finally, the chemical composition of the RPC electrode surface has been analyzed using an electron microscope equipped with an EDS/X-ray.

The BaBar experiment uses a big system based on RPC detectors to discriminate muons from pions and to identify neutral hadrons. About 2000m2 of RPC chambers have been working at SLAC since the end of 1998. We report on the performances of the RPC chambers focusing on new problems discovered in the RPC behaviour. These problems started very soon after the installation of the chambers on the detector when the high-ambient temperature triggered an increase of dark currents inside the chambers and a reduction of the efficiency. Careful analysis of the BaBar data and dedicated R&D efforts in the laboratory have helped to identify the main source of the trouble in the linseed oil varnish on the bakelite electrodes.

The BaBar Collaboration has operated an instrumented flux return (IFR) system covering over 2000m2 with resistive plate chambers (RPCs) for nearly 3 years. The chambers are constructed of bakelite sheets separated by 2mm. The inner surfaces are coated with linseed oil. This system provides muon and neutral hadron detection for BaBar. Installation and commissioning were completed in 1998, and operation began mid-year 1999. While initial performance of the system reached design, over time, a significant fraction of the RPCs demonstrated significant degradation, marked by increased currents and reduced efficiency. A coordinated effort of investigations have identified many of the elements responsible for the degradation. This article presents our current understanding of the aging process of the BaBar RPCs along with the action plan to combat performance degradation of the IFR system.

Resistive Plate Chambers, working in avalanche mode, have been choosen as dedicated muon detector both in barrel and endcap region of the CMS experiment for their fast response and for their capability to be produced as tracking devices on large areas. The production of the barrel RPC chambers will be reported here with special enphasis on the quality control and on the acceptation criteria carried out during the production. Results of the tests with cosmic rays both in production and testing sites will be summerized putting in evidence the problems and the critical issues characterizing the different phases of the construction.

The new SuperKEKB collider will be an upgrade of the existing KEKB electron-positron asymmetric collider, with a target luminosity of 8×1035cm−2s−1, about 40 times greater than the previous one. The accelerator upgrade is based on the novel low-emittance “nanobeams” scheme. The detector will also be upgraded to cope with the higher luminosity, pile-up and occupancy. We report on the development of the new pure CsI calorimeter for the forward region. An intensive R&D has been carried out to study the performance of pure CsI crystals with Avalanche Photodiodes readout. Results on the signal to noise ratio for different sensors and front end electronics configurations will be presented. A matrix of 16 crystals has been tested with the electron beam at the BTF facility in Frascati. Results in terms of energy resolution of this prototype will also be discussed.

Started in 1994 the L3 experiment has been equipped with a forward–backward muon spectrometer triggered by an RPC system. Made of 192 double-gap RPCs, it has been working for six years in streamer mode and it will continue to run at least one year more. We monitored the behaviour of the system during the L3 run periods and in this paper we report on its present status and long-term performance.

The BaBar Collaboration has operated a system covering over 2000 m/sup 2/ with resistive plate chambers for nearly three years. The chambers are constructed of bakelite sheets separated by 2 mm. The inner surfaces are coated with linseed oil. This system provides muon and neutral hadron detection for BaBar. Installation and commissioning were completed in 1998, and operation began mid-1999. While initial performance of the system reached design, over time, a significant fraction of the resistive plate chambers demonstrated significant degradation, marked by increased currents and reduced efficiency. A coordinated investigative effort has identified many of the elements responsible for the degradation.

CMS experiment will use resistive plate chambers (RPCs) as dedicated muon trigger detectors. This requires good chamber global and local performance. To verify the chamber performance intensive tests are going on using a telescope installed at Bari Physics Department. The chamber efficiency is obtained by track reconstruction, which offers also the possibility to perform local efficiency studies. A brief description of the test set-up, reconstruction algorithm and test results are presented in this paper.

The CMS muon system is conceived for trigger and muon track reconstruction. The redundancy and robustness of the system are guaranteed by three complementary subsystems: drift tube in the barrel, cathode strip chamber in the end-cap and resistive plate chamber in barrel and end-cap. The installation of muon stations and read-out trigger electronic has been completed in middle 2007. Since than, a remarkable effort has been addressed to the detector commissioning in order to ensure the readiness of the hardware/software chain for the LHC start up operation. At the end of 2007, a test of an entire CMS slice has been performed, involving about 5% of muon stations. Several thousand cosmic muons events have been collected. Performance of the barrel chambers are reported.

In the CERN CMS experiment at LHC Collider special trigger signals called Technical Triggers will be used for the purpose of test and calibration. The Resistive Plate Chambers (RPC) based Technical Trigger system is a part of the CMS muon trigger system and is designed to detect cosmic muon tracks. It is based on two boards, namely RBC (RPC Balcony Collector) and TTU (Technical Trigger Unit). The proposed tracking algorithm (TA) written in VHDL and implemented in the TTU board detects single or multiple cosmic muon tracks at every bunch crossing along with their track lengths and corresponding chamber coordinates. The TA implementation in VHDL and its preliminary simulation results are presented.

The muon and neutral hadron detector of the BaBar experiment for the PEP-II Asymmetric B-factory at SLAC uses Resistive Plate Counters (RPCs) as active detectors. A large fraction of the total system, which consists of approximately 800 chambers for an overall surface of 2000 m2, has already been built and tested in cosmic rays. Preliminary results of the operating characteristics with a new non-flammable and environmentally safe gas mixture are reported.

Abstract The L3 experiment has recently been upgraded with a Forward-Backward muon spectrometer in view of the LEP 200 physics. Due to their high efficiency and good time resolution, Resistive Plate Counters (RPCs) where chosen for building a system providing the muon trigger in that region. The detector has been successfully built and installed, and the expected performances are confirmed.

The RPC detectors in the L3 experiment at LEP work as a trigger system for the Forward–Backward Muon Spectrometer. It consists of 192 bi-gap RPCs working in streamer mode. We monitored the behaviour of the system over seven years of data taking at LEP. To investigate the ageing of the RPCs after this long-term operation, we report the main results obtained from 1994 to 2000, together with the results of tests performed on some RPC chambers in our test site in Napoli with cosmic rays after the dismantling of L3.

In the CMS experiment, sub-detectors may send special trigger signals, called “Technical Triggers”, for purposes like test and calibration. The Resistive Plate Chambers are part of the Muon Trigger System of the experiment, but might also produce a cosmic muon trigger to be used during the commissioning of the detectors, the CMS Magnet Test-Cosmic Challenge and the later running of CMS. The proposed implementation is based on the development of a new board, the RPC Balcony Collector (RBC); the test results on prototypes and their performance during the recent CMS Cosmic Challenge are presented.

The Resistive Plate Chambers (RPC) detector of the CMS experiment at the LHC proton collider (CERN, Switzerland) will employ an online gas analysis and monitoring system of the freon-based gas mixture used. We give an overview of the CMS RPC gas system, describe the project parameters and first results on gas-chromatograph analysis. Finally, we report on preliminary results for a set of monitor RPC.

Resistive Plate Chambers (RPC) have been chosen as dedicated trigger muon detectors for the Compact Muon Solenoid [CMS collaboration, Technical Design Report, CERN/LHCC 94-38, 1994. [1]] experiment at the Large Hadron Collider [The LHC project at CERN, LHC-project-report-36, 1996. [2]] at CERN. Four Italian groups from Bari, Frascati, Napoli and Pavia and two Bulgarian groups from Sofia have participated in designing and constructing the RPC barrel system. A sophisticated and complex production line has been organized by the collaboration to build the 480 RPC chambers, with a quality assurance (QA) test, made by 3 consecutive steps, in order to assure full functionality of the chambers. A final certification of the chambers has been made at ISR (CERN) with a month-long test. After that the RPCs have been coupled to the Drift Tube chamber and installed in the iron return yoke of the CMS solenoid. The first chamber was produced in 2002 and last was installed in October 2007. The system is now completely installed and commissioning has been going on since the second half of 2005 to complete the Large Hadron Collider (LHC) startup in the summer of 2008. The chamber construction, the test made, the main results achieved and a short description of all the services needed to run the RPC barrel system will be described in this paper.

The L3 detector is designed to measure the muon momentum with a 2% resolution at p = 45 GeV/c. We discuss here the systems we developed to reach the required accuracy and control the mechanical alignment at running time. We also report on the test done on the muon spectrometer with UV lasers and cosmic rays.

The L3 muon spectrometer is presented. Characteristics, useful for experiments at future accelerators, are highlighted. Particular emphasis is given to the systems envisaged to keep the error on the relative alignment of detectors below 30 μm and so reach a momentum resolution Δpp = 2% at p = 45 GeV/c.

We describe the trigger system for the Forward-Backward muon spectrometer of L3 detector. The trigger uses double gap Resistive Plate Counters (RPC) covering an area of 300 m2. This is the first large scale application of this kind of detectors in high energy physics. The main features of these detectors, the trigger architecture and preliminary results are reported.

Abstract The IFR system is a RPC-based detector used to identify muons and neutral hadrons in the BaBar experiment at PEP II machine in SLAC. The RPC system can be used to reconstruct the trajectory of muons, pions and neutral hadrons interacting in the iron of the IFR. The different range and hit pattern allow to discriminate different particles crossing the IFR. An overview of the system design and the preliminary results on the IFR performances are reported.

The Resistive Plate Chambers [M. Abbrescia, et al., Nucl. Instr. and Meth. A 550 (2005) 116] are used in the CMS experiment [CMS Collaboration, The CMS experiment at the CERN LHC 2008, J. Inst. 3 (2008) S08004] as a dedicated muon trigger both in barrel and endcap system. About 4000m2 of double gap RPCs have been produced and have been installed in the experiment since more than one and half Years. The full barrel system and a fraction of the endcaps have been monitored to study dark current behaviour and system stability, and have been extensively commissioned with Cosmic Rays collected by the full CMS experiment.

The BaBar experiment is projected to study CP violation in B decays. Muon detection and KL0 identification are achieved by an Instrumented Flux Return (IFR) system based on resistive plate chamber detectors. In this paper the general layout of the IFR system will be described.

An RPC based system will be employed for the CMS muon first level trigger. Severe quality controls and certification have been established all along the entire production chain. Procedures are briefly described and results for the acceptance percentage are given for the second part of the single gaps and double gaps production. Summary results are also reported for the full sets of tested chambers.

Resistive Plate Chambers have been chosen as dedicated trigger muon detectors for the Compact Muon Solenoid experiment at the Large Hadron Collider at CERN. The barrel RPC detector consists of 480 chambers of different forms and sizes, equipped with 75,000 strips and covering an area of about 2400 m2. About one-third of RPC barrel chambers have been produced up to the end of 2003 and these 150 chambers, produced and assembled in Italy, have been extensively tested at the two Italian test stands of Bari and Pavia by the RPC barrel collaboration. Preliminary results of the production and test of the chambers will be described here.

The Muon System of the CMS experiment at CERN employees three different detector technologies—Drift Tube Chambers (DT) in the barrel part, Cathode Strip Chambers (CSC) in the endcaps and Resistive Plate Chambers (RPC) both in the barrel and the endcaps. TDs and CSCs serve as precise muon trajectory measurement devices. The RPCs are responsible for the bunch crossing identification and for a fast muon transverse momentum measurement. The total number of RPCs is 480 in the barrel and 756 in the endcaps, covering an area of about 3500 square meters. A brief overview of the system will be presented as well as some recent results about the system stability and performance.

The SuperB project is an asymmetric e+e− accelerator of 1036 cm−2s−1 luminosity, capable of collecting a 50–75 ab−1 data sample in five years of running. The SuperB electromagnetic calorimeter (EMC) provides energy and direction measurement of photons and electrons and identification versus other charged particles for electrons. A matrix of 25 LYSO crystals has been tested at the Beam Test Facility at Frascati in May 2011 at energies between 100 MeV and 500 MeV. Results from this test will be presented. Design and Monte Carlo studies for the general EMC system will also be presented.

El objetivo de este estudio es comparar el grado de vinculo que establecen dos estilos de intervención terapéutica, el grado de de empatía (cognitiva y afectiva) con el paciente y el pensamiento mágico (creencias paranormales) entre psicólogos clínicos y practicantes de tarot. Aunque ambos grupos difieren en cuanto a objetivos, instrumentos y procedimientos, sin embargo, hay evidencia empírica que sugiere los tarotistas producen cambios actitudinales, cognitivos, emocionales y existenciales significativos –a menudo positivos– en la vida de sus pacientes/consultantes. Se administró el Test de Empatía Cognitiva y Afectiva, el Inventario de Alianza Terapéutica, y el Cuestionario de Creencias Paranormales junto a una encuesta de estilos y prácticas de consejería (adaptada apropiadamente) a una muestra practicantes de tarot y psicólogos de orientación clínica. Los resultados sugieren que las emociones y las creencias de los pacientes/consultantes no deberían ser un obstáculo sino un “atajo” para empatizar o crear un puente funcional para una psicoterapia exitosa. Aunque no se encontraron diferencias en la construcción de la alianza terapéutica, los psicólogos no priorizaron la empatía con su paciente. De modo que la producción de mayor vínculo cognitivo/emocional entre tarotista/consultante posiblemente sea más flexible que el establecido por el psicoterapeuta/paciente.

Resistive Plate Chambers have been chosen as active elements for the μ and Kl detector in the BaBar experiment. This subsystem, now under construction, represents the most extensive use to date of the RPC technology. The design considerations are presented, together with preliminary results on the operating characteristics.

Measurements of cosmic rays in the L3 multisampling chambers are presented. The study of tracks with polar angles from 30° < θ < 130° w.r.t. the wires show increasing pulse height like 1/sin θ. Using inclined tracks, we find a ±1.5 cm region of reduced accuracy near the glass supports of the 5.4 m long wires.

The above-mentioned measurements, on crystals, photodetectors and optical couplings, performed at INFN and ENEA laboratories and irradiation facilities, represent a thorough study of options, that will allow the optimal solution for the upgrade of the Belle II end cap calorimeter to be found.

The new facility SuperKEKB will be an upgrade of the existing KEKB electron–positron asymmetric collider, with a target luminosity of 8×1035cm−2s−1, about 40 times greater than that of KEKB. The detector will also be upgraded to cope with the higher luminosity, pile-up and occupancy. We report here on the design and development of the new pure CsI calorimeter for the forward region. An intensive R&D is being carried on to study the performance of pure CsI crystals with Avalanche Photodiodes readout. Results about the relative energy resolution of this detector, along with radiation hardness studies of all the components, are presented. A matrix of 16 crystals has been put on an electron beam at the BTF facility in Frascati and results in terms of energy resolution of this prototype are also discussed.

Studying the reaction Studyingpp → μ+ μ−X at the Intersecting Storage Rings (ISR),a special class of events was found for which no hadrons are seen associated with the muon pair in a large solid angle vertex detector. The origin of these events can be most naturally explained as arising from the two-photon process in pp collisions. It is emphasized that this process becomes increasingly interesting at higher hadron colliding facilities.

We present a study of the decay B- --> D0_(CP) K- and its charge conjugate, where D0_(CP) is reconstructed in CP-even, CP-odd, and non-CP flavor eigenstates, based on a sample of 232 million Y(4S) --> B Bbar decays collected with the BABAR detector at the PEP-II e+e- storage ring. We measure the partial-rate charge asymmetries A_CP+, A_CP- and the ratios R_CP+, R_CP- of the B --> D0 K decay branching fractions as measured in CP+, CP-, and non-CP D0 decays: A_CP+ = 0.35 +/- 0.13 (stat) +/- 0.04 (syst) A_CP- = -0.06 +/- 0.13 (stat) +/- 0.04 (syst) R_CP+ = 0.90 +/- 0.12 (stat) +/- 0.04 (syst) R_CP- = 0.86 +/- 0.10 (stat) +/- 0.05 (syst)

The BaBar Collaboration has operated a system covering over 2000 m/sup 2/ with resistive plate chambers for nearly three years. The chambers are constructed of bakelite sheets separated by 2 mm. The inner surfaces are coated with linseed oil. This system provides muon and neutral hadron detection for BaBar. Installation and commissioning were completed in 1998, and operation began mid-year 1999. While initial performance of the system reached design, over time, a significant fraction of the RPCs demonstrated significant degradation, marked by increased currents and reduced efficiency. A coordinated effort of investigations have identified many of the elements responsible for the degradation.

The RPC chambers in the L3 forward-backward muon spectrometer have been operational from 1994 to the end of LEP running.After dismantling of the L3 detector some of the RPCs modules have been transported to Napoli where their performance has been re-measured with cosmic rays.Results of long-term performance in the LEP environment and of laboratory tests with cosmic rays will be presented.One of the 20 tested chambers, the one with the worst performances, was opened.The chamber was inspected with microscope and also a chemical analysis of the oil coating was performed.We will report in detail about this analysis.

In view of LEP200 physics, the L3 detector has been upgraded installing the Forward—Backward muon spectrometer to increase the angular acceptance in muon detection. We describe the trigger system for this spectrometer which makes use of Resistive Plate Counters (RPC) covering an area of 300 m2. This system is the first large application in high energy physics of this kind of detectors and its operation will constitute an important test for their future use in the LHC experiments. The main features of the RPCs, the trigger architecture and the preliminary results from the 1994 LEP run are given.