J. Królikowski

We have searched for νμ oscillations by comparing the rates of νgm charged-current interactions in two detectors located 130 and 885 m from the target, which was struck by a 9.2 GeV/c proton beam from the CERN Proton Synchroton. No evidence for νμ oscillations was found. At the 90% confidence level, Δm2 values between 0.26 and 90 eV2 are excluded for maximal mixing. The most restrictive limit on the neutrino mixing-angle parameter sin22θ is 0.053 at Δm2=2.5 eV2.

A high-statistics measurement of the differential cross-sections for neutrino-iron scattering in the wide-band neutrino beam at the CERN SPS is presented. Nucleon structure functions are extracted and theirQ 2 evolution is compared with the predictions of quantum chromodynamics.

A large sample of opposite-sign dimuons, produced by the interaction of neutrinos and antineutrinos in iron, is analysed. The data agree very well with the hypothesis that the extra muon is the product of charm decay. They yield information on the strength and space-time structure of the charmproducing weak current. The strange-sea structure functionxs(x) is determined. The difference between neutrino and antineutrino dimuon production is analysed to provide a value of the Kobayashi-Maskawa weak mixing angleθ 2.

The ratio ${R}_{\ensuremath{\nu}}$ of the neutral- to charged-current cross sections of neutrinos in iron has been measured in an exposure of the CERN-Dortmund-Heidelberg-Saclay neutrino detector to a 160-GeV/c neutrino narrow-band beam at the CERN Super Proton Synchrotron. The result is ${R}_{\ensuremath{\nu}}=0.3072\ifmmode\pm\else\textpm\fi{}0.0025(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.0020(\mathrm{syst})$, for hadronic energy greater than 10 GeV. The electroweak mixing parameter is ${sin}^{2}{\ensuremath{\theta}}_{W}=0.225\ifmmode\pm\else\textpm\fi{}0.005(\mathrm{expt})\ifmmode\pm\else\textpm\fi{}0.003(\mathrm{theor})+0.013({m}_{c}\ensuremath{-}1.5 \frac{\mathrm{GeV}}{{c}^{2}})$, where ${m}_{c}$ is the charm-quark mass.

The energy resolution and response of a segmented iron-scintillator total absorption calorimeter has been measured for pion energies from 10 to 140 GeV and for electron energies up to 50 GeV. A procedure has been found to weight individual counter responses for hadron showers which results in improved energy resolution at high energies and a nearly linear dependence of response on hadron energy above 30 GeV. There is evidence in the data that this weighting procedure compensates for fluctuations in energy deposition due to the electromagnetic component of the hadronic shower. For an iron sampling thickness of 2.5 cm the hadron energy resolution follows a 0.58E law, while the resolution for electromagnetic showers is 0.23E.

Inclusive charged-current interactions of high-energy neutrinos and antineutrinos have been studied with high statistics in a counter experiment at the CERN Super Proton Synchrotron. The energy dependence of the total cross-sections, the longitudinal structure function, and the nucleon structure functionsF 2,xF 3, and $$\bar q^{\bar v} $$ are determined from these data. The analysis of theQ 2-dependence of the structure functions is used to test quantum chromodynamics, to determine the scale parameter Λ and the gluon distribution in the nucleon.

The CDHS neutrino detector has been used to measure events originating in a tank of liquid hydrogen and in the iron of the detector. Total cross-sections, differential cross-sections, and structure functions are given for hydrogen and compared with those in iron. The measurements are in agreement with the expectations of the quark parton model. No significant differences indicative of nuclear binding effects in corresponding structure functions of protons and iron are observed. This may be of special interest in the case of the sea structure functions, since large differences are expected in some models.

The final results from the WA 1/2 neutrino experiment in the 1984 CERN 160 GeV narrow band beam are presented. The ratiosR ν and $$R_{\bar v} $$ of neutral to charged current interaction rates of neutrinos and antineutrinos in iron are measured to beR ν=0.3072±0.0033 and $$R_{\bar v} $$ =0.382±0.016. A value of the electroweak parameter sin2 θ w = 1 −m 2 /m 2 is extracted fromR ν. The result is sin2 θ w =0.228+0.013(m c −1.5)±0.0003 (theor.) wherem c is the mass of the charmed quark in GeV form t =60 GeV,M H =100 GeV, ρ=1. CombiningR ν and $$R_{\bar v} $$ one obtains a value for ρ=0.991+0.023(m c −1.5)±0.020(exp.). Alternatively,R ν and $$R_{\bar v} $$ yield a precise value of the ratio of intermediate vector boson massesm W /m Z =0.880−0.007(m c −1.5)±0.002(exp.)±0.002(theor.). Comparison of these results with those from direct measurements of the vector boson masses are presented. In a model-independent analysis the left- and right-handed neutral current coupling constants,g 2 andg 2 , are determined.

The observed scaling violations of the nucleon structure functionF 2 and $$\bar q$$ have been analysed in the framework of perturbative QCD to determine the shape and magnitude of the gluon distribution. The data are in good agreement with leading order QCD, and the simultaneous use ofF 2 and $$\bar q$$ structure functions permits, for the first time, a reliable determination of the gluon structure function.

Neutrino and antineutrino total charged current cross sections on iron were measured in the 100, 160, and 200 GeV narrow band beams at the CERN SPS in the energy range 10 to 200 GeV. Assuming σ/E to be constant, the values corrected for non-isoscalarity are σv/E = (0.686 ± 0.019) * 10−38 cm2/ (GeV · nucleon) and σv/E = (0.339 ± 0.010) * 10−38 cm2/ (GeV·nucleon). Between 50 and 150 GeV no energy dependence of σ/E was observed within ±3% for neutrino and ±4% for antineutrino interactions.

Positive correlations are observed for pion pairs of equal charge and similar momentum vectors, produced in the reactions πp→p+5π and πp→p + 7π at 4 to 25 GeV/c. The results are consistent with being due to the second-order interference effects expected for pairs of identical bosons and lead to the determination of the average dimension of the “fire-ball’ from which the pions are emitted (〈R〉 = 1.0 ± −0.2+0.4 fm). Attempts are made to study the fire-ball shape by selecting pions pair emitted in various polar and azimuthal directions.

Using data from a 16 GeV/c π+p bubble chamber experiment, we have studied the production of pions and meson resonances in the central region. Transverse spectra have been analysed in terms of the transverse energy variable Et=√pt2+M2. We find that the Et spectra of “stable” particles, of resonances like ϱ, ω and f, and of corresponding non-resonant two- and three-pion systems all follow one simple exponential in Et over several orders of magnitude in cross section. All spectra are consistent with one common slope parameter of approximately (120 MeV)−1.

Right handed weak quark currents coupled to the usual left handed weak lepton current would be seen in inclusive antineutrino scattering on nuclei as a contribution at largey with the quark (not antiquark) structure function. We do not see such a term, and can therefore put an upper limit on the relative strengths of such right handed currents: $$\varrho ^2 = \frac{{\sigma _R }}{{\sigma _L }}< 0.009$$ , 90% confidence. This measurement puts limits on the mixing angle of left-right symmetric models. In distinction to similar limits derived from muon decay or β decay, our limits are also valid if the right handed neutrino is heavy.

In the interactions of 400 GeV/c protons with copper nuclei, a flux of prompt neutrinos is observed. The reactions produced by these neutrinos in our apparatus appear consistent with those of electron- and muon-neutrinos. The prompt neutrino fluxes are interpreted as being due to associated production and subsequent semileptonic decay of charmed hadrons. The prompt flux ratio $$\bar v_\mu /v_\mu = 0.46_{ - 0.16}^{ + 0.21} $$ suggests a sizeable production of charmed baryons near the forward direction. The ratio of prompte −+e + toµ −+µ + event rates is 0.64 −0.15 +0.22 , where unity is expected frome-μ universality.

A new measurement of the ratio R = σL/σT of longitudinal and transverse structure functions in neutrino interactions on iron between 30 and 190 GeV neutrino energy is reported. The result is given as a function of the scale parameter x and the inelasticity ν of the interaction. The average value is R = 0.10 ± 0.07 around ν ≈ 50 GeV and is in accordance with a prediction from the QCD theory.

The PAC (pattern comparator) is a dedicated muon trigger for the CMS (Compact Muon Solenoid) experiment at the LHC (Large Hadron Collider). The PAC trigger processes signals provided by RPC (resistive plate chambers), a part of the CMS muon system. The goal of the PAC RPC trigger is to identify muons, measure their transverse momenta and select the best muon candidates for each proton bunch collision occurring every 25 ns. To perform this task it is necessary to deliver the information concerning each bunch crossing from many RPC chambers to the trigger logic at the same moment. Since the CMS detector is large (the muon hits are spread over 40 ns), and the data are transmitted through thousands of channels, special techniques are needed to assure proper synchronization of the data. In this paper methods developed for the RPC signal synchronization and synchronous transmission are presented. The methods were tested during the MTCC (magnet test and cosmic challenge). The performance of the synchronization methods is illustrated by the results of the tests.

The general scheme for the fast, pipelined first level trigger on high pt muons in the CMS detector at LHC is presented. The prototype PACT system was tested in the high momentum muon beams in the RD5 experiment during 1993/94 runs. The obtained efficiency curves are shown.

During the summer 2006, a first integrated test of a part of the CMS experiment was performed at CERN collecting a data sample of several millions of cosmic rays events. A fraction of the Resistive Plate Chambers system was successfully operated. Results on the RPC performance are reported.

The paper presents the concept of the Overlap Muon Track Finder (OTF) trigger for the CMS experiment in CERN as a system implemented in the modern FPGA device. The parametrized description of the complex data processing system, allowing further optimization by iterative simulations and recompilations, is presented. Problems associated with synthesis of such complex systems with currently available synthesis tools, and their workarounds are described.

From exposures of the CDHS detector at the CERN SPS we have obtained 367μ + μ − events in neutrino beams and 73μ + μ + events in an antineutrino beam. The magnitude of a prompt like-sign signal has been controversial in the past and moreover could not be explained by known production mechanisms. A critical discussion of the experimental situation is given. We have tried to reduce the systematic uncertainties of previous experiments and to get more information on the dependence of the signal with energy and the muon momentum cut-off. This experiment yields a signal of 2.8σ (2.4σ) of prompt like-sign dimuon events in the case of neutrinos (antineutrinos). The rate to charged current events is of the order of 10−4 forp μ<9GeV andE>100 GeV. The prompt signal has all the properties expected from the production and decay of charm-anticharm events. The magnitude, however, is substantially higher then the prediction of perturbative QCD but lower than some other experiments.

The results of proton irradiation test of electronic devices, selected for the RPC trigger electronic system of the CMS detector, will be presented. For Xilinx Spartan-IIE FPGA the cross-section for Single Event Upsets (SEUs) in configuration bits was measured. The dynamic SEUs in flip-flops were also investigated, but not observed. For the FLASH memories no single upsets were detected. Only after irradiating with a huge dose permanent damages of devices were observed. For Synchronous Dynamic Random Access Memory (SDRAM), the SEU cross-section was measured.

A gas detector with parallel resistive electrodes has intrinsic capability of efficient detection at high particle fluxes. An inverted Double Gap Resistive Plate Chamber made of special bakelite of low resistivity −ρ=5·108Ω cm, reaches full efficiency with a plateau exceeding 500 V for radiation rates as high as 7 kHz/cm2 measured with a periodic beam. A gas mixture containing a majority of so called “green freon” – C2H2F4 assures stable avalanche amplification with a time resolution of about 2 ns, only slightly dependent on the particle flux. Measurements with a strong 137Cs source confirm stability of parameters in continuous radiation flux up to 5 kHz/cm2/gap. The results demonstrate the usefulness of an RPC as a muon trigger detector in a high radiation background environment, expected in the CMS experiment in the highest rapidity region.

The performance of the High-density Projection Chamber (HPC), the barrel electromagnetic calorimeter of the DELPHI experiment, is described. The detector adopts the time projection technique in order to obtain exceptionally fine spatial granularity in the three coordinates (/spl sim/2/spl times/20 mrad/sup 2/ in /spl theta//spl times//spl phi/ with nine samplings along the shower axes), using a limited number of readout channels (18432). Among the various topics concerning the HPC construction and operation, major emphasis is given to the aspects related to the calibration in energy of the calorimeter, based mainly on the analysis of the detector response to /sup 83m/Kr decays, and to the treatment of ageing in the readout proportional counters.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

The total punchthrough probability of showers produced by negatively charged pions of momenta 30, 40, 50, 75, 100, 200 and 300 GeV/c, has been measured in the RD5 experiment at CERN using a toroidal spectrometer. The range of the measurement extends to 5.3 m of equivalent iron. Our results have been obtained by two different analysis methods and are compared with the resutls of a previous experiment.

The inclusive production of neutral particles are studied in π−d interactions at 205 GeV. Topological distributions for the inclusive reactions π−d → γ + d, π−d → Ks0+x, π−d → Γ + x and the cross section for π−d → Γ + x are presented and compared with π−p and pp interactions at 100 and 205 GeV. The effects of double scattering are studied and π−n inclusive distributions are obtained and compared to results from π−p interactions (in hydrogen) at 205 GeV.

This paper presents the implementation of the data acquisition system of the Resistive Plate Chamber (RPC) subdetector in the Compact Muon Solenoid (CMS) experiment at the Large Hadron Collider (LHC) in CERN. The described readout system connects with the RPC detector, the RPC link system, the RPC trigger system and the CMS data acquisition system and creates one of multiple metrological systems in CMS experiment. The readout system receives the data provided by the multiple channels of the link system, filters out the non-triggered data, encapsulates the data into the standard CMS common data format events and sends them to the global data acquisition system. The main problem in the readout system design was to provide a sufficiently large throughput to reliably transfer the data. The implemented system is the scalable solution based on advanced Field Programmable Gate Arrays (FPGA) technology.

This paper describes firmware architecture of a new part of muon trigger system of the CMS detector – one of four detectors installed along LHC accelerator in CERN. Overlap Muon Track Finder (OMTF) is a new trigger subsystem designed to work in difficult barrel-endcap region of CMS detector. OMTF is designed to receive data from different detector types and process it to select 3 best muon candidates. These muon candidates are then forwarded to Global Muon Trigger (GMT). Performance requirements demanded usage of custom designed hardware. All the data reception and processing takes part in modern, large FPGA device. The IPBus module allows easy firmware control and diagnostics via Ethernet connection.

The experiments at the planned 14 TeV proton-proton collider LHC will need a good identification and measurement of muons with energies of up to about 800 GeV. The production of electromagnetic secondaries by muons of energy from 10 to 300 GeV has been measured at the RD5 experiment at CERN using various detector types proposed for LHC experiments. It is demonstrated that the detectors can recognize the presence of individual hits from em secondaries, and that the muon measurement would be seriously compromised if these hits are not suppressed.

The article describes the algorithm of finding the highest transverse momentum muon based on the signals from fast RPC detectors in CMS experiment at the LHC collider in CERN (Geneva). Very fast progress in FPGA performance makes it possible to build Pattern Comparator Processor (PAC) using this technology. Compilation and simulation of different configurations of PAC are discussed. Improved algorithm which requires smaller resources in the FPGAs is presented.

This paper describes the RPC Link Box Control System (RLBCS) developed for the RPC muon trigger in the CMS experiment on LHC collider under construction in CERN (Geneva). RLBCS subsystem is reponsible for relatively slow, bidirectional communication between the link electronics placed on detector and devices of CMS Detector Control System (DCS) located in the control room. The RLBCS is used for diagnostic and control purposes, and therefore it is essential for the RPC muon trigger. The RLBCS is also responsible for configuration of the FPGAs in the RPC link electronics, working in the harsh, irradiated environment. Additionally most part of the RLBCS itself works in the irradiated area, so assuring its reliable operation required some special solutions. All the above factors make this subsystem an important and non-trivial task in the CMS RPC muon trigger development.

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 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 results of proton radiation test of electronic devices for RPC trigger electronic system of CMS detector are presented. For Xilinx Spartan-IIE FPGA the cross section for Single Event Upsets (SEUs) in configuration bits was measured. The dynamic SEUs in flip-flops was also investigated, but not observed. For the FLASH memories no single upsets were detected, but after a huge dose permanent damages of devices were observed. For SDRAM memories, the SEU cross section was measured. A brief description of radiation inducted effects in FPGAs, SRAM and FLASH memories is also presented.

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.

Proton-proton collisions in the LHC accelerator will occur every 25 ns. The muon trigger of the CMS experiment will have to analyze data from 200 000 channels of RPC chambers every bunch crossing. Special compression algorithm has been developed to transmit the data from the chambers to the trigger electronics through optical fibers. The data flow has been simulated, and the data loss estimate is presented.

This paper describes the design of the Link Box Control System for the RPC Detector (RLBCS), emphasizing the features needed to assure reliable operation in the irradiated environment of the RPC detector and its neighbourhood. The development process required to balance different factors - radiation hardness, reliability, flexibility, firmware upgrade possibilities, diagnostic features. The final design presented in the paper is a result of compromise between the above requirements.

The resistive plate chambers (RPCs) muon trigger electronics of the Compact Muon Solenoid (CMS) detector performs a number of tasks: synchronization of detector signals, optical data transmission from the detector to the trigger electronics, pattern recognition, muons momentum measurement, selection of track candidates. For the diagnostic purposes, as well as for the calibration and real-time monitoring of the RPC detectors and electronic hardware, a set of flexible diagnostic modules was designed and implemented into the field programmable gate arrays on which the trigger electronics is based. These include: multichannel counters, timing histograms, test pulses generators, diagnostic readout and data spying ("snap-shots" of the data stream). Test results presented in this paper, including tests with Large Hadron Collider-like muon beam, illustrate the performance and the usefulness of these diagnostic modules

Angular correlations between pairs of secondary particles emitted in 4- and 6-prong events of π+p interactions at 16 GeV/c are studied as functions of the effective mass M of the two particles involved. It is argued that this is superior to the usual technique of studying correlations as functions of Δy (the difference in the rapidities of two particles), because effects of different origins such as resonance production and Bose-Einstein interference, which all occur predominantly at Δy ≈ 0, are well separated when plotted in terms of the mass. It is shown that the angular correlations are strongly affected by the production of two-particle resonances such as ϱ0, f, and g mesons for (π+π−) pairs, and Δ++(1232) and Δ++(1890) isobars for the (pπ+) pairs. A variable D(M) is proposed, related to the difference in angular correlations of pairs of like and unlike charges, which is shown to be effective in enhancing resonance signals and could be useful also at higher energies.

Abstract Three medium-size Resistive Plate Chambers (RPCs) with bakelite electrodes having resistivity of 5×10 8 , 5×10 9 and 3×10 10 Ω cm were tested in the Gamma Irradiation Facility at CERN in 1997, 1998 and 1999. The 2 mm gap modules working in an Inverted Double Gap configuration filled with gas mixtures containing freon C 2 H 2 F 4 and operated in avalanche mode exhibit wide efficiency plateau, good time resolution and small time walk due to rate variation even at intensities as high as 1 kHz / cm 2 / gap of a continuous radiation flux.

This paper presents a distributed control system developed for TriDAQ boards prepared for Resistive Plate Chamber (RPC) detector in Compact Muon Solenoid (CMS) Muon Trigger system to be used in Large Hadron Colider (LHC) in CERN. The control systme is based on Linux servers embedded in TriDAQ boards. The communication between embedded servers and managing/data processing host is assured by the Ethernet network. The embedded controllers offer sufficient computational power to perform board diagnostics and preprocessing of acquired data. Presented solution assures both high flexibility (due to configuration by the network) and high performance (due to highly parallel architecture).

An Inverted Double Gap Resistive Plate Chambers (RPC) made of bakelite of 5×109Ωcm volume resistivity was tested at avalanche rates up to 1kHz/cm2/gap in the Gamma Irradiation Facility at CERN in 2001. The inner surfaces of the chamber electrodes were cladded using linseed oil varnish. Dependence of the intrinsic RPC noise and the stability of the gas gain on the gas temperature and the gas composition are discussed.

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 full scale prototype of an Inverted Double Gap RPC module for ME-1/1 station of the CMS detector was tested in the Gamma Irradiation Facility at the CERN SPS muon beam. The chamber made of medium resistivity bakelite and filled with “green gas” mixture of C2H2F4/iso-butane/SF6 has wide efficiency plateau and good timing properties when operated in avalanche mode under continuous irradiation with strong 137Cs source for rates up to about 5 kHz/cm2/gap.

The baseline crate and link layout is described in CMS IN 2000/044 and Trigger TDR. In the present paper an attempt is made to improve on the baseline design by minimizing the number of crates as well as the number and the lengths of interconnections.

The RPC muon trigger electronics of the CMS detector performs a number of tasks: synchronization of detector signals, optical data transmission from the detector to the trigger electronics, pattern recognition, muon momentum measurement, selection of track candidates. For the diagnostic purposes, as well as for the calibration and real-time monitoring of the RPC detectors and electronic hardware, a set of flexible diagnostic modules was designed and implemented into the FPGAs on which the trigger electronics is based. These include: multi-channel counters, timing histograms, test pulses, and data spying ("snapshots" of the data stream). Tests results presented in this paper, including test with LHC-like muon beam, illustrate the performance and usefulness of these diagnostic modules.

We report on the search of composite organic materials with the volume resistivity ranging from 108 to 1011Ωcm. Materials having resistivity in this range may be used for electrodes of thin gap Parallel Plate Avalanche Chambers. Gas detectors of such structure and operated at increased gas pressure allow, potentially, a sub-nanosecond time resolution. Using bakelite-like material with electrical properties well tuned during manufacturing opens the possibility to overcome limitations related to the semi-conductive glass employed usually for ultrafast gas detectors of parallel plate structure for time-of-flight technique.

In this paper the object oriented hardware-software model and its sample implementation of diagnostics for the Overlap Muon Track Finder trigger for the CMS experiment in CERN is described. It presents realization of test-bench for control and diagnosis class of multichannel, distributed measurement systems based on FPGA chips. The test-bench fulfills requirements for system’s rapid changes, configurability and efficiency. This ability is very significant and desirable by expanded electronic systems. The solution described is a software model based on a method of address space management called the Component Internal Interface (CII). Establishment of stable link between hardware and software, as a purpose of designed and realized programming environment, is presented. The test-bench implementation and example of OMTF algorithm test is presented.

A gas detector made of three parallel electrodes (bakelite electrode and two metallic mesh electrodes) and working in proportional mode allows monitoring of the gas gain under various intensities of X-rays over long period of time. The detector performance, when irradiated with an intense radiation flux, and possible effects of variation of the bakelite electrode conductivity on a medium-term stability of operation are reported. The results shown in this paper were obtained for detector filled with argon/isobutane gas mixture.

Environmental Engineering III – Pawlowski, Dudzin´ska & Pawlowski (eds) © 2010 Taylor & Francis Group, London, ISBN 978-0-415-54882-3

The momentum and angular distributions of punchthrough muons have been measured after a 10 λ calorimeter using an iron toroid magnet with 1.5 T as spectrometer. The calorimeter was inside a variable magnetic field of 0 to 3 T. The incident momentum of the π− beam ranged from 20 to 300 GeV/c. Measurements were also done at some beam momenta for π+, K+ and p. The results are compared with Monte Carlo predictions. A parameterization for the momentum spectrum of punchthrough muons was derived from the data.

The algorithm for a L1 muon trigger based on six RPC planes is described. Single muon L1 rates and efficiencies are presented. Simulations of L1 RPC Trigger rates from prompt muons, RPC noise and neutron background are shown. The 6 planes algorithm leads to large reduction of false triggers originating from ghosts and uncorrelated background.

Two single gap medium-size RPC modules, made of bakelite plates of very good mechanical quality of the surface and having initial volume resistivity of 1×1010Ωcm, were tested in the Gamma Irradiation Facility at CERN at ionisation rates up to 1kHz/cm2. The internal surfaces facing the gas volume of one RPC module were cladded with a thin layer of linseed oil varnish for comparison of oiled and non-oiled RPC operation. The results refer to the gas mixture of C2H2F4/isobutane (97:3) with SF6 addition below 1%. The single gap modules exhibited full detection efficiency plateau for the high voltage range of about 1 kV at full intensity of gamma rays. Good timing characteristics allowed to reach 95% efficiency at fully opened irradiation source with time window of 20 ns. The intrinsic noise rate for a non-oiled and an oiled RPC gap was, respectively, below 5 and 1Hz/cm2 at full efficiency over 1 kV voltage range.

A novel position-sensitive micro-pattern gas detector called Sand-Glass is introduced. It has been manufactured using printed circuit board technique and its structure is based on two thin kapton foils joined together. The foils are copper-clad on both sides with the strip electrodes structure engraved on either side, and with a very dense perforation in the form of a conically shaped hole pattern etched through both foils, which forms the Sand-Glass shape. The two foils are in electrical contact; the outer faces form cathodes, and the inner layer becomes an anode. Due to the electric field symmetry, electrons from avalanches are collected on the central electrode of the Sand-Glass holes. This geometry may allow 2D readout in the single gas amplification structure. Preliminary results of the SGG detector prototype tests are reported.

The deterioration of the calorimeter response to electrons in the presence of upstream material has been investigated inside a magnetic field. Data for different absorber thicknesses, distances and electron energies are compared to Monte Carlo calculations. Results are extended to the geometrical situation of a typical collider detector.

The total punchthrough probability of showers produced by negative pions, positive pions, positive kaons and protons, has been measured as a function of depth in an absorber in a magnetic field ranging from 0 to 3 Tesla. The incident particle momentum varied from 10 to 300 GeV/c. The lateral shower development and particle multiplicity at several absorber depths have been determined. The measurements are compared with the predictions of Monte Carlo simulation programs.