O. Kortner

The Monitored Drift Tube (MDT) chambers for the muon spectrometer of the ATLAS detector at the Large Hadron Collider (LHC) consist of 3–4 layers of pressurized drift tubes on either side of a space frame carrying an optical monitoring system to correct deformations. The full-scale prototype of a large MDT chamber has been constructed with methods suitable for large-scale production. X-ray measurements at CERN showed a positioning accuracy of the sense wires in the chamber of better than the required 20 μm (rms). The performance of the chamber was studied in a muon beam at CERN. Chamber production for ATLAS now has started.

Two ATLAS sMDT drift tubes have been irradiated for almost 1 year using a 90Sr beta-decay source. An integrated charge of 62 C has been accumulated on each of both anode wires over an anode-wire region of about 7.5 cm. Taking into account the intensity distribution of the irradiation corresponds to a maximum accumulated line charge density of about 14 C/cm. At the innermost position of the ATLAS forward muon spectrometer 10 C/cm are expected for 10 years of high-luminosity LHC operation and for this detector type at gas gain 20000. To investigate potential outgassing, the endplug region of the drift-tubes, where no gas amplification occurs, was irradiated additionally using about half the beta-electrons emitted from the source. The other beta-electrons were irradiating an active part of the gas volume for monitoring purpose. During four months the endplugs were irradiated by 5 C/cm equivalent. All observed anode currents were very stable over the whole period of irradiation and thus no sign of deterioration in the performance of both drift tubes was observed. This indicates that no ageing effects occurred and that no performance loss due to outgassing of any plastic surfaces has been observed. All components that have potential contact to the detector gas Ar:CO2 with a mixture of 93:7 (percent volume) have been carefully and properly chosen. The required cleanliness of all tube- and gas components has been achieved during construction and operation of these drift tubes.

The muon detectors of the experiments at the Large Hadron Collider (LHC) have to cope with unprecedentedly high neutron and gamma ray background rates. In the forward regions of the muon spectrometer of the ATLAS detector, for instance, counting rates of 1.7 kHz/square cm are reached at the LHC design luminosity. For high-luminosity upgrades of the LHC, up to 10 times higher background rates are expected which require replacement of the muon chambers in the critical detector regions. Tests at the CERN Gamma Irradiation Facility showed that drift-tube detectors with 15 mm diameter aluminum tubes operated with Ar:CO2 (93:7) gas at 3 bar and a maximum drift time of about 200 ns provide efficient and high-resolution muon tracking up to the highest expected rates. For 15 mm tube diameter, space charge effects deteriorating the spatial resolution at high rates are strongly suppressed. The sense wires have to be positioned in the chamber with an accuracy of better than 50 ?micons in order to achieve the desired spatial resolution of a chamber of 50 ?microns up to the highest rates. We report about the design, construction and test of prototype detectors which fulfill these requirements.

We present an R&D activity aiming to develop a new detector concept in the framework of the ATLAS pixel detector upgrade in view of the Super-LHC. The new devices combine 75–150 μm thick pixels sensors with a vertical integration technology. A new production of thin pixel sensors on n- and p-type material is under way at the MPI Semiconductor Laboratory. These devices will be connected to the ATLAS read-out electronics with the new Solid–Liquid InterDiffusion technique as an alternative to the bump-bonding process. We also plan for the signals to be extracted from the back of the electronics wafer through Inter-Chip-Vias. The compatibility of the Solid–Liquid InterDiffusion process with the silicon sensor functionality has already been demonstrated by measurements on two wafers hosting diodes with an active thickness of 50 μm.

For the muon spectrometer of the ATLAS detector at the Large Hadron Collider (LHC), large drift chambers consisting of 6–8 layers of pressurized drift tubes are used for precision tracking covering an active area of 5000m2 in the toroidal field of superconducting air-core magnets. The chambers have to provide a spatial resolution of 41μm with Ar:CO2 (93:7) gas mixture at an absolute pressure of 3bar and gas gain of 2×104. The environment in which the chambers will be operated is characterized by high neutron and γ background with counting rates of up to 100s−1cm−2. The resolution and efficiency of a chamber from the serial production for ATLAS has been investigated in a 100GeV muon beam at photon irradiation rates as expected during LHC operation. A silicon strip detector telescope was used as external reference in the beam. The spatial resolution of a chamber is degraded by 4μm at the highest background rate. The detection efficiency of the drift tubes is unchanged under irradiation. A tracking efficiency of 98% at the highest rates has been demonstrated.

In the ATLAS muon spectrometer, large drift-tube chambers are used for precision tracking. The chambers will be operated at a high neutron and /spl gamma/ background resulting in count rates of up to 500 Hz cm/sup -2/ corresponding to 300 kHz per tube. The spatial resolution of the drift tubes is degraded from 82 /spl mu/m without background to 108 /spl mu/m at 500 Hz cm/sup -2/ background count rate. Due to afterpulsing in the Ar/CO/sub 2/ gas mixture used in the drift tubes, ionizing radiation causes more than one hit in a tube within the maximum drift time of about 800 ns which is expected for magnetic field strengths around 1.2 T. In order to limit the count rate, the drift tubes are read out with an artificial dead time of 790 ns which causes an efficiency loss of 23% at a rate of 300 kHz per tube. The space-to-drift-time relationship of the tubes varies with background rate, temperature, and magnetic field strength. The mean magnetic field strength in a muon chamber is 0.4 T on the average, but may vary by up to 0.4 T within a chamber. The space-to-drift-time relationship must therefore be determined in short time intervals with an accuracy better than 20 /spl mu/m using muon tracks and applying corrections for measured magnetic field variations.

Prominent KK¯ resonances observed in the in-flight annihilation of p¯p into K+K−π0 include f2(1270), f0(1500), f2′(1525), ϕ(1680)/ρ(1700) and a state at 1750 MeV/c2 consistent with f0(1710). The reaction cross sections σ(p¯p→X(K+K−)π0) are obtained by means of a partial wave analysis. When these are combined with known KK¯ partial widths, the resulting production rates of presumably non-nn¯ states, X=f0(1710) and f2′(1525), are found to be suppressed by an order of magnitude compared to f0(1500) and f2(1270), respectively.

Small-diameter muon drift tube (sMDT) detectors have been developed for upgrades of the ATLAS muon spectrometer. With a tube diameter of 15 mm, they provide an about an order of magnitude higher rate capability than the present ATLAS muon tracking detectors, the MDT chambers with 30 mm tube diameter. The drift-tube design and the construction methods have been optimised for mass production and allow for complex shapes required for maximising the acceptance. A record sense wire positioning accuracy of 5 μm has been achieved with the new design. In the serial production, the wire positioning accuracy is routinely better than 10 μm. 14 new sMDT chambers are already operational in ATLAS, further 16 are under construction for installation in the 2019–2020 LHC shutdown. For the upgrade of the barrel muon spectrometer for High-Luminosity LHC, 96 sMDT chambers will be contructed between 2020 and 2024.

Drift tube chambers are commonly used in many experiments in High Energy Physics (HEP). This paper addresses the problem of particle track finding in a drift tube chamber. Although drift tubes have, in general, a high efficiency to detect the passage of particles, in a high radiation background some of the particle hits will be masked by background hits. Under the assumption of high tube efficiency, a novel track finding algorithm, denoted as the Drift Tube Hough Transform (DTHT) algorithm, is presented. The DTHT algorithm uses the possible explanations for a lack of particle hits as additional information, and takes into account all possible scenarios that may occur in the tubes. The DTHT is implemented with a novel extension of the Hough transform and employs a ``detect before estimate'' approach that first finds the track candidates and then estimates the track parameters. In order to evaluate the performance of the DTHT algorithm, the algorithm was applied to the Monitored Drift Tube (MDT) of the ATLAS experiment and tested using a muon test beam in a high radiation background. It is shown that the use of the additional information reduces the number of fake track rate significantly. A comparison between the DTHT algorithm and the currently best performed program in the ATLAS software, demonstrated that the DTHT algorithm can achieve higher efficiency while reducing the algorithm complexity.

We describe a system test of the ATLAS muon spectrometer performed at the H8 beam line of the CERN Super-Proton-Synchrotron (SPS) during 2003. The setup includes one barrel tower made of six Monitored Drift Tube chambers equipped with an alignment system and four Resistive Plate Chambers, and one end-cap octant consisting of six end-cap MDT equipped with an alignment system and one triplet and two doublets of Thin Gap Chambers. Many system aspects of the muon spectrometer have been studied with this setup, from the performance of the precision and trigger chambers to the capability to align the precision chambers at the level of a few tens of micrometers and to operate the muon trigger at the crossing frequency of the LHC.

In 2004, a combined system test was performed in the H8 beam line at the CERN SPS with a setup reproducing the geometry of sectors of the ATLAS Muon Spectrometer, formed by three stations of Monitored Drift Tubes (MDT). The full ATLAS analysis chain was used to obtain the results presented in this paper. The basic design performances of the Muon Spectrometer were verified. The stability of MDT calibration constants, the alignment system using optical devices and high energy tracks, as well as the intrinsic sagitta resolution of the Muon Spectrometer were studied and found to agree with expectations. The reconstruction of muon tracks using the combined information from both the Inner Detector and the Muon Spectrometer are also presented.

Pressurized drift-tube chambers are efficient detectors for high-precision tracking over large areas. The Monitored Drift-Tube (MDT) chambers of the muon spectrometer of the ATLAS detector at the Large Hadron Collider (LHC) reach a spatial resolution of 35μm and almost 100% tracking efficiency with 6 layers of 30 mm diameter drift tubes operated with an Ar:CO2 (93:7) gas mixture at 3 bar and a gas gain of 20 000. The ATLAS MDT chambers are designed to cope with background counting rates due to neutrons and γ rays of up to about 300 kHz per tube which will be exceeded for LHC luminosities larger than the design value of 1034 cm−1 s−1. Decreasing the drift-tube diameter to 15 mm while keeping the other parameters, including the gas gain, unchanged reduces the maximum drift time from about 700 to 200 ns and the drift-tube occupancy by a factor of 7. New drift-tube chambers for the endcap regions of the ATLAS muon spectrometer have been designed. A prototype chamber consisting of 12 times 8 layers of 15 mm diameter drift tubes of 1 m length has been constructed with a sense wire positioning accuracy of 20μm. The 15 mm diameter drift-tubes have been tested with cosmic rays in the Gamma Irradiation Facility at CERN at γ counting rates of up to 1.85 MHz.

The performance of pressurized drift-tube detectors at very high background rates has been studied at the Gamma Irradiation Facility (GIF) at CERN and in an intense 20 MeV proton beam at the Munich Van-der-Graaf tandem accelerator for applications in large-area precision muon tracking at high-luminosity upgrades of the Large Hadron Collider (LHC). The ATLAS muon drifttube (MDT) chambers with 30 mm tube diameter have been designed to cope with and neutron background hit rates of up to 500 Hz/square cm. Background rates of up to 14 kHz/square cm are expected at LHC upgrades. The test results with standard MDT readout electronics show that the reduction of the drift-tube diameter to 15 mm, while leaving the operating parameters unchanged, vastly increases the rate capability well beyond the requirements. The development of new small-diameter muon drift-tube (sMDT) chambers for LHC upgrades is completed. Further improvements of tracking efficiency and spatial resolution at high counting rates will be achieved with upgraded readout electronics employing improved signal shaping for high counting rates.

For the planned high-luminosity upgrades of the Large Hadron Collider (LHC) background rates of neutrons and gamma rays of up to 14kHz/cm2 are expected which exceed the rate capability of the current ATLAS precision muon tracking detectors, the Monitored Drift Tube (MDT) chambers, with a drift tube diameter of 30 mm. Smaller diameter drift tube (sMDT) chambers with 15 mm tube diameter have been developed for upgrades of the ATLAS muon spectrometer. A full sMDT prototype chamber has been constructed and tested in a muon beam at CERN and with cosmic muons at high background irradiation rates of up to 95kHz/cm2 and 1400 kHz/tube. The test results demonstrate the required track reconstruction efficiency and spatial resolution of the sMDT chambers at background rates well beyond the maximum expected values at high-luminosity LHC. The sense wire locations in the prototype chamber have been measured with few microns precision with cosmic rays using precise reference chambers confirming the required wire positioning accuracy of better than the 20μm.

The experience of the ATLAS MDT muon spectrometer shows that drift-tube chambers provide highly reliable precision muon tracking over large areas. The ATLAS muon chambers are exposed to unprecedentedly high background of photons and neutrons induced by the proton collisions. Still higher background rates are expected at future high-energy and high-luminosity colliders beyond HL-LHC. Therefore, drift-tube detectors with 15 mm tube diameter (30 mm in ATLAS), optimised for high rate operation, have been developed for such conditions. Several such full-scale sMDT chambers have been constructed with unprecedentedly high sense wire positioning accuracy of better than 10 μm. The chamber design and assembly methods have been optimised for large-scale production, reducing considerably cost and construction time while maintaining the high mechanical accuracy and reliability. Tests at the Gamma Irradiation Facility at CERN showed that the rate capability of sMDT chambers is improved by more than an order of magnitude compared to the MDT chambers. By using read-out electronics optimised for high counting rates, the rate capability can be further increased.

The monitored drift tube (MDT) chambers for the muon spectrometer of the ATLAS detector at the Large Hadron Collider (LHC) consist of three or four layers of pressurised drift tubes on either side of a space frame carrying an optical deformation monitoring system. The chambers have to provide a track position resolution of 40 /spl mu/m with a single-tube resolution of at least 80 /spl mu/m and a sense wire positioning accuracy of 20 /spl mu/m (rms). The feasibility was demonstrated with the full-scale prototype of one of the largest MDT chambers with 432 drift tubes of 3.8 m length. For the ATLAS muon spectrometer, 88 chambers of this type have to be built. The first chamber has been completed with a wire positioning accuracy of 14 /spl mu/m (rms).

When the peak luminosity of 1034cm−2s−1 of the LHC will be increased by a factor of 5–7 in about a decade from now (“SLHC”), the selectivity of the ATLAS Level-1 (L1) triggering system will have to be improved in order to cope with the maximum allowed trigger rate of about 100 kHz. For the L1 trigger of the ATLAS Muon Spectrometer this calls for an increase of the pT-threshold for single muons. In the present L1 muon trigger system, however, the effective pT-threshold is not very sharp due to the limited spatial resolution of the trigger chambers, resulting in a majority of L1 triggers from muons below threshold. We describe a new, high-speed readout system of the Monitored Drift Tube chambers, which allows to supply the precision coordinates of the candidate muon to the L1 trigger, resulting in an accurate momentum determination, a sharpened pT-threshold and an efficient rejection of unwanted L1 triggers from low-pT muons.

For use at the future Super-LHC a new type of muon detector has been developed. It is based on the proven MDT drift tube design, but with tubes of half the diameter, leading to higher rate capabilities by an order of magnitude. We present test results on efficiency and position resolution at high background rates and describe the practical implementation in a real-size prototype.

Single muon triggers are crucial for the physics programmes at hadron collider experiments. To be sensitive to electroweak processes, single muon triggers with transverse momentum thresholds down to 20 GeV and dimuon triggers with even lower thresholds are required. In order to keep the rates of these triggers at an acceptable level these triggers have to be highly selective, i.e. they must have small accidental trigger rates and sharp trigger turn-on curves. The muon systems of the LHC experiments and experiments at future colliders like FCC-hh will use two muon chamber systems for the muon trigger, fast trigger chambers like RPCs with coarse spatial resolution and much slower precision chambers like drift-tube chambers with high spatial resolution. The data of the trigger chambers are used to identify the bunch crossing in which the muon was created and for a rough momentum measurement while the precise measurements of the muon trajectory by the precision chambers are ideal for an accurate muon momentum measurement. A compact muon track finding algorithm is presented, where muon track candidates are reconstructed using a binning algorithm based on a 1D Hough Transform. The algorithm has been designed and implemented on a System-On-Chip device. A hardware demonstration using Xilinx Evaluation boards ZC706 has been set-up to prove the concept. The system has demonstrated the feasibility to reconstruct muon tracks with a good angular resolution, whilst satisfying latency constraints. The demonstrated track-reconstruction system, the chosen architecture, the achievements to date and future options for such a system will be discussed.

The outer shell of the ATLAS experiment at the LHC consists of a system of toroidal air-core magnets in order to allow for the precise measurement of the transverse momentum (pT) of muons, which in many physics channels are a signature of interesting physics processes [1,2]. For the precise determination of the muon momentum Monitored Drift Tube chambers (MDT) with high position accuracy are used, while for the fast identification of muon tracks chambers with high time resolution are used, able to select muons above a predefined pT threshold for use in the first Level of the ATLAS triggering system (Level-1 trigger). When the LHC peak luminosity of 1034 cm−2s−1 will be increased by a factor of 4–5 in about a decade from now (''SLHC''), an improvement of the selectivity of the ATLAS Level-1 triggering system will be mandatory in order to cope with the maximum allowed trigger rate of 100 kHz. For the Level-1 trigger of the ATLAS muon spectrometer this means an increase of the pT threshold for single muons. Due to the limited spatial resolution of the trigger chambers, however, the selectivity for tracks above ∼ 20 GeV/c is insufficient for an effective reduction of the Level-1 rate. We describe how the track coordinates measured in the MDT precision chambers can be used to decisively improve the selectivity for high momentum tracks. The resulting increase in latency will also be discussed.

The resolution and efficiency of a precision drift-tube chamber for the ATLAS muon spectrometer with final read-out electronics was tested at the Gamma Irradiation Facility at CERN in a 100GeV muon beam at photon irradiation rates of up to 990Hz/cm2, which corresponds to twice the highest background rate expected in ATLAS. A silicon strip detector telescope served as external reference in the beam. The pulse-height measurement of the read-out electronics was used to perform time-slewing corrections, which lead to an improvement of the average drift-tube resolution from 104 to 82μm without irradiation, and from 128 to 108μm at the maximum expected rate. The measured drift-tube efficiency agrees with the expectation from the dead time of the read-out electronics up to the maximum expected rate.

The ATLAS muon spectrometer uses tracking chambers consisting of up to 5 m long drift tubes filled with Ar:CO2(93:7) at 3 bar. The chambers are run in a average toroidal magnetic field of 0.4 T created by 8 air core coils. They provide a track-point accuracy of 40μm if the space-to-drift-time relationship r(t) is known with 20μm accuracy. The magnetic field B influences the electron drift inside the tubes: the maximum drift time tmax=700ns increases by ≈70ns/T2B2. B varies by up to ±0.4T along the tubes of the chambers mounted near the magnet coils which translates into a variation of tmax of up to 45 ns. The dependence of r(t) on B must be taken into account. Test-beam measurements show that the electron drift in case of B≠0 can be modelled with the required accuracy by a Langevin equation with a friction term which is slightly non-linear in the drift velocity.

The precise measurement of muon momenta up to 1 TeV/c is one of the most challenging aspects of the ATLAS experiment at the Large Hadron Collider (LHC) at CERN. The ATLAS muon spectrometer is equipped with three layers of Monitored Drift Tube (MDT) chambers in a magnetic field generated by a superconducting air-core magnet system which are designed to cope with neutron background counting rates of up to 500 cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−2</sup> s <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−1</sup> . However, 10 times higher background rates are to be expected at Super-LHC, the high-luminosity upgrade of the LHC. We investigate the possibility of increasing the rate capability of the drift tube detectors by reducing the tubes diameter from the current value of 30 mm to 15 mm. Cosmic ray test results of a prototype detector with 15 mm diameter drift tubes in the presence of γ ray fluxes of up to 2000 cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−2</sup> s <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−1</sup> are discussed.

Precision drift tube chambers with a sense wire positioning accuracy of better than 20μm are under construction for the ATLAS muon spectrometer. 70% of the 88 large chambers for the outermost layer of the central part of the spectrometer have been assembled. Measurements during chamber construction of the positions of the sense wires and of the sensors for the optical alignment monitoring system demonstrate that the requirements for the mechanical precision of the chambers are fulfilled.

The size and complexity of LHC experiments raise unprecedented challenges not only in terms of detector design, construction and operation, but also in terms of software models and data persistency. One of the most challenging tasks is the calibration of the 375,000 Monitored Drift Tubes (MDTs) that will be used as precision tracking detectors in the Muon Spectrometer of the ATLAS experiment. This paper reviews the status of the MDT Calibration software and computing model. In particular, the options for a dedicated database are described.

ATLAS muon detector upgrades aim for increased acceptance for muon triggering and precision tracking and for improved rate capability of the muon chambers in the high-background regions of the detector with increasing LHC luminosity. The small-diameter Muon Drift Tube (sMDT) chambers have been developed for these purposes. With half of the drift-tube diameter of the MDT chambers and otherwise unchanged operating parameters, sMDT chambers share the advantages of the MDTs, but have an order of magnitude higher rate capability and can be installed in detector regions where MDT chambers do not fit in. The chamber assembly methods have been optimized for mass production, minimizing construction time and personnel. Sense wire positioning accuracies of 5 μm have been achieved in serial production for large-size chambers comprising several hundred drift tubes. The construction of new sMDT chambers for installation in the 2016/17 winter shutdown of the LHC and the design of sMDT chambers in combination with new RPC trigger chambers for replacement of the inner layer of the barrel muon spectrometer are in progress.

In order to fully exploit the physics potential of the ATLAS experiment at the HL-LHC, the trigger rate of and maximum latency of the first-level trigger system will be increased to 1 MHz and 10μs, respectively. In addition, a new first-level muon track trigger with high momentum resolution based on the ATLAS precision Muon Drift-Tube (MDT) chambers will be employed which requires triggerless readout. The TDC ASICs of the current front-end electronics of the MDT chambers are incompatible with these requirements. The front-end boards, each with a TDC chip and three 8-channel amplifier–shaper–discriminator (ASD) chips have to be replaced. Therefore, a new octal ASD2 ASIC has been developed in modern 130 nm IBM/Global Foundries CMOS technology. The chip also contains a Wilkinson ADC to perform both time-over-threshold and signal charge measurement. The ASD design has been fully qualified for the serial production of 80000 chips for ATLAS. The performance in terms of signal rise time and channel uniformity significantly surpasses the one of the previous chip while keeping the power consumption constant. In addition to the characterization with test pulses, several chips have been mounted on the front-end boards and tested in a muon beam at the Gamma Irradiation Facility GIF++ at CERN up to high counting rates where the superior drift time and spatial resolution becomes evident.

The design of a muon detector and first-level muon trigger system for the FCC-hh baseline experiment is presented. The baseline FCC-hh detector configuration with a solenoid magnet system providing a field integral of 18 Tm over a wide pseudorapidity interval and a muon system around the solenoid and the calorimeter system is assumed. In order to identify muons with high momentum resolution one needs to measure the muon incidence angle at the entry point of the muon system with an angular resolution better than 100 μrad. This precision can be achieved with chambers with two quadruple layers which are separated by a 1.5 m thick spacer structure and contain 15 mm diameter aluminium drift tubes filled with Ar:CO(93:7) at 3 bars absolute pressure. Each drift-tube chamber is combined with a double layer of thin-gap RPC chambers which provide bunch crossing identification with better than 1 ns time resolution, muon trigger seeds, and coordinate measurement along the tubes.

This paper presents the design and experimental characterization of a 28 nm Complementary Metal Oxide Semiconductor (CMOS) Analog Front-End (AFE) for fast-tracking small-diameter Muon Drift-Tube (sMDT) detectors. The device exploits an innovative analog signal processing that allows a strong increase in the detection rate of events and significantly reduces the impact of fake/pile-up events, which often corrupt incident radiation energy events. The proposed device converts the input charge coming from incident radiations into voltage by a dedicated Charge-Sensitive Preamplifier (CSPreamp). Therefore, the fast-tracking concept relies on sampling the slope of the CSPreamp output voltage and using it for detecting both the incident event arrival instant and the amount of charge that has been effectively read out by MDT detectors. This avoids the long processing times intrinsically needed for baseline recovery transient, during which the detected signal can be severely corrupted by additional and unwanted extra-events, resulting in extra-charge (and thus in CSP output voltage extra-transient) during the signal roll-off. The proposed analog channel operates with a 5–100 fC input charge range and has a maximum dead-time of 200 ns (against the 545 ns of the state-of-the-art). It occupies 0.03 mm2 and consumes 1.9 mW from 1 V of supply voltage.

Monitored Drift Tube (MDT) chambers will constitute the large majority of precision detectors in the Muon Spectrometer of the ATLAS experiment at the Large Hadron Collider at CERN. For commissioning and calibration of MDT chambers, a Cosmic Ray Measurement Facility is in operation at Munich University. The objectives of this facility are to test the chambers and on-chamber electronics, to map the positions of the anode wires within the chambers with the precision needed for standalone muon momentum measurement in ATLAS, and to gain experience in the operation of the chambers and on-line calibration procedures. Until the start of muon chamber installation in ATLAS, 88 chambers built at the Max Planck Institute for Physics in Munich have to be commissioned and calibrated. With a data taking period of one day individual wire positions can be measured with an accuracy of 8.3 micrometers in the chamber plane and 27 micrometers in the direction perpendicular to that plane.

The muon spectrometer of the ATLAS experiment at the large hadron collider (LHC) is instrumented with three layers of precision tracking detectors each consisting of 6 or 8 layers of pressurized aluminum drift tubes of 30 mm diameter. The magnetic field of the spectrometer is generated by superconducting air-core toroid magnets. Already at the LHC design luminosity of 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">34</sup> cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> s <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> , the ATLAS muon chambers have to cope with unprecedentedly high neutron and gamma ray background rates of up to 500 Hz/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> in the inner and middle chamber layers in the forward regions of the spectrometer. At a high-luminosity upgrade of the LHC (S-LHC), the background rates are expected to increase by an order of magnitude. The resulting high occupancies lead to a significant deterioration of the muon detection efficiency compromising the physics goals. The possibility to improve the muon detection efficiency by reducing the diameter of the drift tubes has been investigated. We report about the design and test results of prototype drift-tube detectors with thin-walled aluminum tubes of 15 mm diameter.

In the ATLAS Muon Spectrometer, Monitored Drift Tube (MDT) chambers and sMDT chambers with half of the tube diameter of the MDTs are used for precision muon track reconstruction. The sMDT chambers are designed for operation at high counting rates due to neutron and gamma background irradiation expected for the HL-LHC and future hadron colliders. The existing MDT read-out electronics uses bipolar signal shaping which causes an undershoot of opposite polarity and same charge after a signal pulse. At high counting rates and short electronics dead time used for the sMDTs, signal pulses pile up on the undershoot of preceding background pulses leading to a reduction of the signal amplitude and a jitter in the drift time measurement and, therefore, to a degradation of drift tube efficiency and spatial resolution. In order to further increase the rate capability of sMDT tubes, baseline restoration can be used in the read-out electronics to suppress the pile-up effects. A discrete bipolar shaping circuit with baseline restoration has been developed and used for reading out sMDT tubes under irradiation with a 24 MBq <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">90</sup> Sr source. The measurements results show a substantial improvement of the performance of the sMDT tubes at high counting rates.

Resistive plate chambers (RPCs) with electrodes of high-pressure phenolic laminate and small gas gap widths down to 1 mm provide large area tracking at relatively low cost in combination with high rate capability and fast response with excellent time resolution of better than 500 ps. Thin-gap RPCs will be employed in the upgrade of the barrel muon system of the ATLAS experiment at HL-LHC. The large demand for RPCs exceeds the presently available production capacities. At the same time, the requirements on mechanical precision, reliability and reproducibility for collider detectors have increased. Additional suppliers with industry-style quality assurance are urgently needed. We have established RPC production procedures compliant with industrial requirements and are in the process of certifying several companies for RPC production for the ATLAS upgrade for HL-LHC and beyond. We report about the technology transfer, the RPC prototype production at the selected companies and the results of the certification procedure.

Resistive plate chambers (RPCs) with thin gas gaps (1 mm) between two high-pressure phenolic laminate plates offer excellent time resolution down to a few hundred picoseconds and a decent spatial resolution of the order of a few millimeters. As RPCs can be produced at relatively low costs they are the ideal choice for the instrumentation of large areas of many experiments. In order to set up a production at external companies we investigated several modifications of the established production procedures of RPCs in order to adapt it to the available devices at different companies and to facilitate the technology transfer to industry. In our contribution we will describe our studies and compare the different options for the individual production steps. We shall present the results of our a test production carried out in our institute and show the performance of the produced gaps obtained in tests with muons from cosmic rays.

Resistive plate chambers (RPCs) with electrodes of high-pressure phenolic laminate and small gas gap widths down to 1 mm provide large area tracking at relatively low cost in combination with high rate capability and fast response with excellent time resolution of better than 500 ps. They are perfectly suited for experiments requiring sub-nanosecond time resolution and spatial resolution on the order of a few millimeters over large areas. Thin-gap RPCs will therefore be used for the upgrade of the barrel muon system of the ATLAS experiment at HL-LHC and are candidates for the instrumentation of future collider detectors and experiments searching for long-lived particles in experiments like ANUBIS. RPCs are also frequently used in large area cosmic ray detectors. The large demand for RPCs exceeds the presently available production capacities. At the same time, the requirements on mechanical precision, reliability and reproducibility for collider detectors have increased, especially with the reduced gas gap widths. Additional suppliers with industry-style quality assurance are therefore urgently needed. We have established RPC production procedures compliant with industrial requirements and are in the process of certifying several companies for RPC production for the ATLAS upgrade for HL-LHC and beyond. We report about the technology transfer, the RPC prototype production at the selected companies and the results of the certification procedure, as well as their performance and stability measurements in laboratory tests and at CERN SPS X5 120GeV muon beams under high rate <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">137</sup> Cs irradiation.

In the next long shutdown for the Phase-2 Upgrade of the Large Hadron Collider (LHC) in 2026–2028, the 96 new integrated muon tracking and trigger modules will be installed at the ends of the toroid magnet coils in the small azimuthal sectors of the inner barrel layer (BIS1-6) of the ATLAS muon spectrometer in order to increase the trigger efficiency in the barrel region and to improve the rate capability of the muon chambers in the regions of high background rate corresponding to the High Luminosity-LHC project. The new muon module consists of the smallDiameter Muon Drift Tube (sMDT) chamber with a 15 mm tube diameter and thin-gap Resistive Plate Chamber (RPC) triplet with 1 mm gas gap thickness. Due to the narrow available space, the BIS1-6 project foresees to replace the all-existing Monitored Drift Tubes, used for the precise position measurement in this area, with muon stations formed by sMDT and RPC, capable of withstanding the higher rates and provide a robust standalone muon confirmation. Moreover, the advantages of sMDT technology are not only to make room for the new trigger chambers, but it has already demonstrated their excellent precise tracking measurement over large areas at high background rates. In the next few years, ATLAS MDT group of the Max Planck Institute for Physics (MPI) in Munich will produce the 48 sMDT detectors with a total number of the drift tube of about 27000. For this reason, the detailed common assembly protocol and quality control procedures have been established, with the ambitious goal to ensure standardization of the performance of the constructed detectors and their components. In this contribution, we present the final results of the QC tests performed on the 48 BIS1-6 sMDT chambers assembled by the MPI Munich production site following the well-defined specification parameters.

Classical chi-square quantities are appropriate tools for fitting analytical parameter-dependent models to (multidimensional) measured histograms. In contrast, this article proposes a family of special chi-squares suitable for fits with models which simulate experimental data by Monte Carlo methods, thus introducing additional randomness. We investigate the dependence of such chi-squares on the number of experimental and simulated events in each bin, and on the theoretical parameter-dependent weight linking the two kinds of events. We identify the unknown probability distributions of the weights and their inter-bin correlations as the main obstacle to a general performance analysis of the proposed chi-square quantities.

A cosmic ray measurement facility has been set up at Munich University and is used at present to commission and calibrate monitored drift tube (MDT) chambers for the muon spectrometer of the ATLAS experiment. Each tested chamber - produced in collaboration with the Max-Planck-Institut fur Physik and the Joint Institute for Nuclear Research in Dubna - consists of 432 drift tubes with a diameter of 3 cm, which are arranged in 2 /spl times/ 3 layers, and measure 3.8 m /spl times/ 2.2 m /spl times/ 0.5 m. The response of all drift tubes and its homogeneity across the chamber is measured in the cosmic ray facility. Two MDT chambers which were precisely mapped with an X-ray tomograph provide reference tracking for the enclosed third chamber which is to be calibrated. The sense wire positions are determined from a comparison of its drift time measurements with the reference tracks. The geometry of the tested chamber - the grid constants of the drift tubes in a layer, the distances and tilt angles of the layers - can then be derived from these positions. Alignment systems are used to monitor chamber movements at the micrometer level. In the ongoing series commissioning, a rate of 1 chamber per week has been reached. The parameters describing the geometry of the MDT chambers are determined with a precision in the 10 /spl mu/m range. The measurements with cosmic muons complement the chamber surveys performed during construction and will provide an important input for the calibration of the entire ATLAS muon spectrometer.

The resolution and efficiency of a precision drift-tube chamber for the ATLAS muon spectrometer with final read-out electronics was tested at the Gamma Irradiation Facility at CERN in a 100GeV muon beam at photon irradiation rates of up to 990Hz/cm2, which corresponds to twice the highest background rate expected in ATLAS. A silicon strip detector telescope served as external reference in the beam. The pulse-height measurement of the read-out electronics was used to perform time-slewing corrections, which lead to an improvement of the average drift-tube resolution from 104 to 82μm without irradiation, and from 128 to 108μm at the maximum expected rate. The measured drift-tube efficiency agrees with the expectation from the dead time of the read-out electronics up to the maximum expected rate.

We present the prototype of a time-to-digital (TDC) ASIC for the upgrade of the ATLAS Monitored Drift Tube (MDT) detector for high-luminosity LHC operation. This ASIC is based on a previously submitted demonstrator ASIC designed for timing performance evaluation, and includes all features necessary for the various operation modes, as well as the migration to the TSMC 130 nm CMOS technology. We present the TDC design with the emphasis on added features and performance optimization. Tests of the timing performance demonstrate that this ASIC meets the design specifications. The TDC has a bin size of about 780 ps, and a timing bin variations within 40 ps for all 24 channels with leading and trailing edge digitization, while the power consumption has been limited to 250 mW, corresponding to a consumption of about 5.2 mW per edge measurement.

This paper presents a Fast-Tracker front-end (FTfe) for ATLAS small-diameter Muon Drift Tube (sMDT) detectors of the Phase-II Upgrade HL-LHC.This design addresses the higher rate capability required by sMDT and reduces the dead-time below the maximum drift time, further increasing the efficiency.The front-end ensures a fast baseline restoration with a reset interval of maximum 160 ns, so that the secondary spurious pulses are avoided and the successive muon signals can be detected soon and correctly.The device has been designed in 1V-28nm-CMOS technology; 4.7mV/fC sensitivity and 0.24fC ENC are achieved with a core area of 0.03mm 2 .

The goals of the ongoing and planned ATLAS muon detector upgrades are to increase the acceptance for precision muon momentum measurement and triggering and to improve the rate capability of the muon chambers in the high-background regions corresponding to the increasing LHC luminosity. Small-diameter Muon Drift Tube (sMDT) chambers have been developed for these purposes. With half the drift-tube diameter of the current ATLAS Muon Drift Tube (MDT) chambers with 30 mm drift tube diameter and otherwise unchanged operating parameters, the sMDT chambers share all the advantages of the MDTs, but have an about an order of magnitude higher rate capability and can be installed in detector regions where MDT chambers do not fit in. The construction of twelve chambers for the feet regions of the ATLAS detector has been completed for the installation in the winter shutdown 2016/17 of the Large Hadron Collider. The purpose of this upgrade of the ATLAS muon spectrometer is to increase the acceptance for three-point muon track measurement which substantially improves the muon momentum resolution in the regions concerned.

The ATLAS experiment at the Large Hadron Collider (LHC) at CERN is currently being assembled to be ready to take data in 2007. Its muon spectrometer is designed to achieve a momentum resolution better than 10% at 1 TeV. In the barrel part, a toroidal air-core magnet is instrumented with three layers of Monitored Drift Tube (MDT) chambers for precision tracking. The Max-Planck-Institut für Physik and the Ludwig-Maximilians-University in Munich have built 88 MDT chambers for the outermost barrel layer. We report on our experience with the tests of the MDT chambers, their integration with the Resistive Plate trigger chambers and the installation of the muon stations in the experiment. First results of their commissioning in the ATLAS detector will be presented.

Abstract The ATLAS muon spectrometer consists of three layers of precision drift-tube chambers in an average toroidal magnetic field of 0.4 T. Muon tracks are reconstructed with 97% efficiency and a momentum resolution of better than 10% for transverse momenta up to 1 TeV / c . The latter requires misalignment corrections of the track curvature with an accuracy of about 30 μ m which are provided by an optical alignment monitoring system. A method has been developed to measure relative chamber positions with curved muon tracks with comparable precision in order to increase the redundancy of the alignment system. During the operation of the LHC at its design luminosity of 10 34 cm - 2 s - 1 , the muon chambers will be exposed to a high flux of neutrons and γ rays which may lead to occupancies of up to 16%. Based on test-beam data taken at the Gamma-Irradiation Facility at CERN, we show that the anticipated reconstruction efficiency can be achieved with the precision chambers in this environment and how it can be sustained at even higher background rates which are expected for a possible luminosity upgrade of the LHC.

The alignment system of the muon spectrometer of the future LHC experiment ATLAS is described here. Emphasis is put on the optical system, and the fitting programs used to calculate the actual muon chamber positions. Finally, some results validating the alignment are briefly given.

A cosmic ray measurement facility has been set up at Ludwig-Maximilians-University Munich (LMU) and is used at present to commission and calibrate Monitored Drift Tube (MDT) chambers for the muon spectrometer of the ATLAS experiment. Each of these chambers-produced in collaboration with the Max-Planck-Institut fuumlr Physik and the Joint Institute for Nuclear Research in Dubna-consists of 432 drift tubes with a diameter of 3 cm, which are arranged in 2times3 layers, and measures 3.8 mtimes2.2 mtimes0.5 m. At the LMU site, the MDT chambers are completed, equipped with their final front-end electronics and taken into operation for the first time. The gas leak rate of the chamber is determined and its high voltage stability is tested. The response of all drift tubes and its homogeneity across the chamber is measured in the Cosmic Ray Facility. Two MDT chambers which were precisely mapped with an X-Ray tomograph provide reference tracking for the enclosed third chamber which is to be calibrated. The sense wire positions are determined from a comparison of the drift time measurements with the reference tracks. The geometry of the tested chamber-the grid constants of the drift tubes in a layer, the distances and tilt angles of the layers-can then be derived from these positions. Alignment systems are used to monitor chamber movements at the micrometer level. In the ongoing series commissioning, a rate of one chamber per week has been achieved. The parameters describing the geometry of the MDT chambers are determined with a precision in the 10 mum range. The measurements with cosmic muons complement the chamber surveys performed during construction and will provide an important input for the calibration of the entire ATLAS muon spectrometer

The muon spectrometer of the ATLAS experiment at the Large Hadron Collider is designed to measure the muon momenta of up to 1 TeV/c with a resolution of better than 10% in a toroidal magnetic field of superconducting air–core magnets. The muon track sagitta is measured in three layers of pressurized drift-tube chambers. The precision muon chambers have to be aligned with an accuracy of better than 30μm in the track bending plane. An optical alignment system monitors movements of the muon chambers with a precision of few microns. In order to determine the chamber positions in the spectrometer, the initial chamber positions have to be measured with 30μm accuracy using straight muon tracks from proton–proton collisions in a dedicated run of the ATLAS detector with the toroid magnets turned off. A Least Square algorithm has been developed which determines the misalignment parameters of a complete azimuthal sector of the barrel part of the muon spectrometer. It has been tested with straight cosmic muon tracks during the commissioning of the ATLAS experiment. Simulations show that the required alignment accuracy is reached with 100,000 muons per sector originating from the interaction point with transverse momentum greater than 10 GeV. About half of the barrel chambers have already been aligned with 30μm accuracy using cosmic muons.

The proposed upgrade of the Large Hadron Collider at CERN to luminosities above 1 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">34</sup> cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-2</sup> s <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> necessitates the replacement of a large number of tracking chambers of the muon spectrometer of the ATLAS experiment to avoid deterioration of the muon identification and the momentum measurement at high background rates. Based on the standard ATLAS Monitored Drift Tube chambers (2 × 3 or 4 tube layers, drift tube diameter 30 mm), a new design with 15 mm diameter tubes and matching services has been developed, offering an increased rate capability and better pattern recognition and redundancy due to the higher cell density. A full-sized prototype chamber consisting of 1152 tubes arranged in 2 × 8 tube layers and covering an area of 1 m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> has been built to validate the assembly procedures and to test its performance.

Monitored drift tube chambers are used as precision tracking detectors in the muon spectrometer of the ATLAS experiment at the LHC at CERN. These chambers provide a spatial resolution of 35 mm and a tracking efficiency of close to 100 % up to background rates of 0.5 kHz/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> , the former being limited at higher rates mainly due to space charge effects and the latter due to the maximum drift time of 700 ns. For LHC upgrades, a faster drift tube chamber has been developed, using drift tubes with a diameter of 15mm instead of 30 mm. The increased channel density and shorter drift time of about 200 ns raise the rate capability to about 10 kHz/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> , while retaining the spatial resolution. A prototype chamber with trapezoidal shape consisting of 2×8 layers of 15mm diameter drift tubes with an active surface of 0.8 m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> has been constructed. This chamber has been tested at CERN with a 180 GeV muon beam (H8) and with cosmic ray muons at the Gamma Irradiation Facility (GIF) at high γ radiation rates.

We study pi0pi0 correlations in the exclusive reaction ppbar -&gt; 4pi0 at rest with complete reconstruction of the kinematics for each event. The inclusive distribution shows a dip at small invariant mass of the pion pair while a small enhancement in the double differential distribution is observed for small invariant masses of both pion pairs. Dynamical models with resonances in the final state are shown to be consistent with the data while the stochastic HBT mechanism is not supported by the present findings.

The muon spectrometer of the LHC detector ATLAS provides an independent and precise muon track measurement using three layers of precision drift tube chambers in a toroidal magnetic field with a bending power ∫Bdl of 2Tm to 8Tm. Muon tracks are reconstructed with 97% efficiency and a momentum resolution about 3% for most of the range and better than 10% for transverse momenta up to 1 TeV/c. The latter requires the knowledge of the magnetic field with 1% accuracy and misalignment corrections of the track curvature with an accuracy of about 30μm. The magnetic field is measured by Hall probes on each chamber with sufficient precision. The misalignment corrections are given by a system of optical sensors. We present methods which allow us to measure the performance of the muon spectrometer during the operation of the ATLAS detector. The alignment of the chambers can be verified with single muon tracks by making use of redundant momentum measurements in the spectrometer. The muon reconstruction efficiency and the momentum resolution can be determined with muons from Z decays.

The ATLAS experiment at the Large Hadron Collider (LHC) at CERN is currently being assembled to be ready to take first data in 2008. Its muon spectrometer is designed to achieve a momentum resolution of better than 10% up to transverse muon momenta of 1 TeV. The spectrometer consists of one barrel and two endcap superconducting air-core toroid magnets instrumented with three layers of precision drift chambers as tracking detectors and a dedicated trigger system. Detailed studies have been performed with a new approach of the autocalibration, a method to determine the space-to-drift- time relation of the ATLAS MDT chambers, and are presented.

The ATLAS muon spectrometer consists of three layers of precision drift-tube chambers in an air-core toroid magnet system with an average field of 0.4 T. The muon momenta are determined with high accuracy from the measurement of the sagitta of the muon tracks in the three chamber layers. In order to achieve the required momentum resolution of the muon spectrometer of better than 4% for transverse momenta below 400 GeV/c and of 10% at 1 TeV/c, the relative positions of the muon chambers are measured by a system of optical sensors with an accuracy of 30 mum. In order to verify the correctness of the optical alignment, a method has been developed to measure the relative chamber positions with muon tracks which are recorded during the operation of the experiment. For this purpose, an independent estimate of the muon momenta is needed. This is not provided with sufficient accuracy by the track measurement in the inner detector because of energy loss fluctuations in the calorimeters. For muons of <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">PT</sub> < 40 GeV/c, however, the momenta can be determined with high-enough precision independently of the relative misalignment of the chambers from comparison of the local track direction measurements in the individual chamber layers. This method allows for monitoring of the chamber positions with an accuracy of about 30 mum in time intervals of a few hours during LHC operation.

The High-Luminosity Large Hadron Collider will increase the sensitivity of the ATLAS experiment to rare physics processes. In order to cope with a 10 times higher instantaneous luminosity compared to the LHC, the trigger system of ATLAS needs to be upgraded. The ATLAS experiment plans to increase the maximum rate capability of the 1st trigger level to 1 MHz at 10 µs latency. This requires new on- and off-chamber electronics for its muon spectrometer. The planned upgrade of the on-chamber electronics for the ATLAS Muon Drift-Tube (MDT) chambers is de- scribed in this proceedings.

In the ATLAS muon spectrometer, large drift-tube chambers are used for precision tracking. These chambers will he operated at a high neutron and /spl gamma/ background resulting in count rates of up to 500 counts s/sup -1/ cm/sup -2/ corresponding to 300 kHz per tube. The spatial resolution of the drift tubes is degraded from 82 /spl mu/m without background to 108 /spl mu/m at 500 Hz cm/sup -2/ background count rate. In order to limit the background count rate, the drift tubes are read out with an artificial dead time of 790 ns which causes an efficiency loss of 23% at a rate of 300 kHz per tube. The space-to-drift-time relationships of the tubes vary with the background rate, the temperature, and the magnetic field strength. They must be recalibrated in short time intervals with an accuracy better than 20 /spl mu/m which is guaranteed by an autocalibration procedure using muon tracks and by applying measured magnetic field corrections to the relationship.

The ATLAS muon spectrometer uses drift-tube chambers for precision tracking. The performance of these chambers in the presence of magnetic field and high radiation fluxes is studied in this article using test-beam data recorded in the Gamma Irradiation Facility at CERN. The measurements are compared to detailed predictions provided by the Garfield drift-chamber simulation programme.

In the ATLAS Muon Spectrometer, Monitored Drift Tube (MDT) chambers and sMDT chambers with half of the tube diameter of the MDTs are used for precision muon track reconstruction. The sMDT chambers are designed for operation at high counting rates due to neutron and gamma background irradiation expected for the HL-LHC and future hadron colliders. The existing MDT read-out electronics uses bipolar signal shaping which causes an undershoot of opposite polarity and same charge after a signal pulse. At high counting rates and short electronics dead time used for the sMDTs, signal pulses pile up on the undershoot of preceding background pulses leading to a reduction of the signal amplitude and a jitter in the drift time measurement and, therefore, to a degradation of drift tube efficiency and spatial resolution. In order to further increase the rate capability of sMDT tubes, baseline restoration can be used in the read-out electronics to suppress the pile-up effects. A discrete bipolar shaping circuit with baseline restoration has been developed and used for reading out sMDT tubes under irradiation with a 24 MBq 90Sr source. The measurements results show a substantial improvement of the performance of the sMDT tubes at high counting rates.

Monitored Drift Tube (MDT) chambers account for the vast majority of precision tracking chambers in the Muon Spectrometer of the ATLAS experiment at the Large Hadron Collider (LHC), where they have to sustain unprecedentedly high background radiation. New, so-called sMDT chambers with reduced tube diameter have been developed for operation at even higher rates, expected after the upgrade of the LHC to high luminosities (HL-LHC). A new ASD chip is required for future upgrades of the MDT chamber front-end electronics and desirable for full exploitation of the rate capability of the sMDT chambers.

For the upgrade of the ATLAS muon spectrometer in March 2014 new muon tracking chambers (sMDT) with drift-tubes of 15 mm diameter, half of the value of the standard ATLAS Monitored Drift-Tubes (MDT) chambers, and 10 µm positioning accuracy of the sense wires have been constructed.The new chambers are designed to be fully compatible with the present ATLAS services but, with respect to the previously installed ATLAS MDT chambers, they are assembled in a more compact geometry and they deploy two additional tube layers that provide redundant rack information.The chambers are composed of 8 layers of in total 624 aluminum drift-tubes.The assembly of a chamber is completed within a week.A semi-automatized production line is used for the assembly of the drift-tubes prior to the chamber assembly.The production procedures and the quality control tests of the single components and of the complete chambers will be discussed.The wire position in the completed chambers have been measured by using a coordinate measuring machine.

For the upgrade of the ATLAS muon spectrometer in March 2014 new muon tracking chambers (sMDT) with drift-tubes of 15 mm diameter, half of the value of the standard ATLAS Monitored Drift-Tubes (MDT) chambers, and 10 μm positioning accuracy of the sense wires have been constructed. The new chambers are designed to be fully compatible with the present ATLAS services but, with respect to the previously installed ATLAS MDT chambers, they are assembled in a more compact geometry and they deploy two additional tube layers that provide redundant rack information. The chambers are composed of 8 layers of in total 624 aluminum drift-tubes. The assembly of a chamber is completed within a week. A semi-automatized production line is used for the assembly of the drift-tubes prior to the chamber assembly. The production procedures and the quality control tests of the single components and of the complete chambers will be discussed. The wire position in the completed chambers have been measured by using a coordinate measuring machine.

Small-diameter muon drift tube (sMDT) chambers are a cost-effective technology for high-precision muon tracking. The rate capability of the sMDT chambers has been extensively tested at the Gamma Irradiation Facility at CERN in view of expected rates at future high-energy hadron colliders. Results show that it fulfills the requirements over most of the acceptance of muon detectors. The optimization of the read-out electronics to further increase the rate capability of the detectors is discussed. Chambers of this type are under construction for upgrades of the muon spectrometer of the ATLAS detector at high LHC luminosities. Design and construction procedures have been optimized for mass production while providing a precision of better than 10 micrometers in the sense wire positions and the mechanical stability required to cover large areas.

Small-diameter Muon Drift Tube (sMDT) chambers have been developed for the ATLAS muon detector upgrade. They possess an improved rate capability and a more compact design with respect to the existing chambers, which allows to equip detector regions uninstrument at present. The chamber assembly methods have been optimized for mass production, while the sense wire positioning accuracy is improved to below ten microns. The chambers will be ready for installation in the winter shutdown 2016/17 of the Large Hadron Collider. The design and construction of the new sMDT chambers for ATLAS will be discussed as well as measurements of their precision and performance.

Highly selective first-level triggers are essential to exploit the full physics potential of the ATLAS experiment at High-Luminosity LHC (HL-LHC). The concept for a new muon trigger stage using the precision monitored drift tube (MDT) chambers to significantly improve the selectivity of the first-level muon trigger is presented. It is based on fast track reconstruction in all three layers of the existing MDT chambers, made possible by an extension of the first-level trigger latency to 6 μs and a new MDT read-out electronics required for the higher overall trigger rates at the HL-LHC. Data from pp-collisions at √s = 8 TeV is used to study the minimal muon transverse momentum resolution that can be obtained using the MDT precision chambers, and to estimate the resolution and efficiency of the MDT-based trigger. A resolution of better than 4.1% is found in all sectors under study. With this resolution, a first-level trigger with a threshold of 18 GeV becomes fully efficient for muons with a transverse momentum above 24 GeV in the barrel, and above 20 GeV in the end-cap region.

This chapter contains sections titled: Sources of Muons Energy Loss of Muons and Muon Identification Measurement of Muon Momenta Muon Identification in ATLAS and CMS ATLAS and CMS Muon Chambers Muon Track Reconstruction and Identification References

A hodoscope consisting of a set of scintillation counters has been instrumented in order to provide the trigger of the cosmic rays used for the study of the performance of the ATLAS MDT-BIS chamber 'Beatrice' at the X5/GIF (Gamma Irradiation Facility) at CERN. In this note the setup is described and results from calculations and measurements for the hodoscope performance are provided.

The High-Luminosity Large Hadron Collider will increase the sensitivity of the ATLAS experiment to rare physics processes. In order to cope with a 10 times higher instantaneous luminosity compared to the LHC, the trigger system of ATLAS needs to be upgraded. The ATLAS experiment plans to increase the maximum rate capability of the 1st trigger level to 1 MHz at 6μs latency. This requires new on- and off-chamber electronics for its muon spectrometer. The replacement of the precision chamber read-out electronics will make it possible to include their data in the 1st level trigger decision and thus to increase the selectivity of the 1st level muon trigger. The acceptance of the present RPC trigger system in the barrel region will be increased from 75% to 95% by the installation of additional thin-gap RPC with a substantially increased high-rate capability compared to the current RPCs.

Small-diameter muon drift tube (sMDT) chambers with 15 mm tube diameter are a cost-effective technology for high-precision muon tracking over large areas at high background rates as expected at future high-energy hadron colliders including HL-LHC. The chamber design and construction procedures have been optimized for mass production and provide sense wire positioning accuracy of better than 10 ?m. The rate capability of the sMDT chambers has been extensively tested at the CERN Gamma Irradiation Facility. It exceeds the one of the ATLAS muon drift tube (MDT) chambers, which are operated at unprecedentedly high background rates of neutrons and gamma-rays, by an order of magnitude, which is sufficient for almost the whole muon detector acceptance at FCC-hh at maximum luminosity. sMDT operational and construction experience exists from ATLAS muon spectrometer upgrades which are in progress or under preparation for LHC Phase 1 and 2.

The outer shell of the ATLAS experiment at the LHC consists of a system of toroidal air-core magnets in order to allow for the precise measurement of the transverse momentum (p <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T</sub> ) of muons, which in many physics channels are a signature of interesting physics processes. For the precise determination of the muon momentum Monitored Drift Tube chambers (MDT) with high position accuracy are used, while for the fast identification of muon tracks chambers with high time resolution are used, able to select muons above a predefined p <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T</sub> threshold for use in the first Level of the ATLAS triggering system (Level-1 trigger). When the LHC peak luminosity will be increased by a factor of 4-5 in about a decade from now (”SLHC”), an improvement of the selectivity of the ATLAS Level-1 triggering system will be mandatory in order to cope with the maximum allowed trigger rate of 100 kHz. For the Level-1 trigger of the ATLAS muon spectrometer this means an increase of the p <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T</sub> threshold for single muons. Due to the limited spatial resolution of the trigger chambers, however, the selectivity for tracks above ~20 GeV/c is insufficient for an effective reduction of the Level-1 rate. We describe how the track coordinates measured in the MDT precision chambers can be used to decisively improve the selectivity for high momentum tracks. The resulting increase in latency will also be discussed.

The High-Luminosity LHC (HL-LHC) will provide the unique opportunity to explore the nature of physics beyond the Standard Model of strong and electroweak interactions. Highly selective first-level triggers are essential for the physics programme of the ATLAS experiment at HL-LHC, where the instantaneous luminosity will exceed the instantaneous LHC Run 1 luminosity by about an order of magnitude. The ATLAS first-level muon trigger rate is dominated by low momentum muons, which are accepted because of the moderate momentum resolution of the RPC and TGC trigger chambers. This limitation can be overcome by exploiting the data of the precision Muon Drift-Tube (MDT) chambers in the first-level trigger decision. This requires continuous fast transfer of the MDT hits to the off-detector trigger logic and fast track reconstruction algorithms. The reduction of the muon trigger rate achievable with the proposed new trigger concept, the performance of a novel fast track reconstruction algorithm, and the first hardware demonstration of the scheme with muon testbeam data taken at the CERN Gamma Irradiation Facility are discussed.

The goals of the ongoing and planned ATLAS muon detector upgrades are to increase the acceptance for precision muon momentum measurement and triggering and to improve the rate capability of the muon chambers in the high-background regions corresponding to the increasing LHC luminosity. Smalldiameter Muon Drift Tube (sMDT) chambers have been developed for these purposes. With half the drift-tube diameter of the current ATLAS Muon Drift Tube (MDT) chambers with 30 mm drift tube diameter and otherwise unchanged operating parameters, the sMDT chambers share all the advantages of the MDTs, but have an about an order of magnitude higher rate capability and can be installed in detector regions where MDT chambers do not fit in. The construction of twelve chambers for the feet regions of the ATLAS detector has been completed for the installation in the winter shutdown 2016/17 of the Large Hadron Collider. The purpose of this upgrade of the ATLAS muon spectrometer is to increase the acceptance for three-point muon track measurement which substantially improves the muon momentum resolution in the regions concerned.

The High-Luminosity LHC will provide the unique opportunity to explore the nature of physics beyond the Standard Model of strong and electroweak interactions. Highly selective first level triggers are essential for the physics programme of the ATLAS experiment at the HL-LHC where the instantaneous luminosity will exceed the LHC Run 1 instantaneous luminosity by almost an order of magnitude. The ATLAS first level muon trigger rate is dominated by low momentum muons, selected due to the moderate momentum resolution of the resistive plate and thin gap trigger chambers. This limitation can be overcome by including the data of the precision muon drift tube (MDT) chambers in the first level trigger decision. This requires the fast continuous transfer of the MDT hits to the off-detector trigger logic and a fast track reconstruction algorithm performed in the trigger logic. In order to demonstrate the feasibility of reconstructing tracks in MDT chambers within the short available first-level trigger latency of about 3 μs we implemented a seeded Hough transform on the ARM Cortex A9 microprocessor of a Xilinx Zynq FPGA and studied its performance with test-beam data recorded in CERN's Gamma Irradiation Facility. We could show that by using the ARM processor's Neon Single Instruction Multiple Data Engine to carry out 4 floating point operations in parallel the challenging latency requirement can be matched.

The High-Luminosity LHC (HL-LHC) will provide the unique opportunity to explore the nature of physics beyond the Standard Model of strong and electroweak interactions. Highly selective first-level triggers are essential for the physics programme of the ATLAS experiment at HL-LHC, where the instantaneous luminosity will exceed the instantaneous LHC Run 1 luminosity by about an order of magnitude. The ATLAS first-level muon trigger rate is dominated by low momentum muons, which are accepted because of the moderate momentum resolution of the RPC and TGC trigger chambers. This limitation can be overcome by exploiting the data of the precision Muon Drift-Tube (MDT) chambers in the first-level trigger decision. This requires continuous fast transfer of the MDT hits to the off-detector trigger logic and fast track reconstruction algorithms. The reduction of the muon trigger rate achievable with the proposed new trigger concept, the performance of a novel fast track reconstruction algorithm, and the first hardware demonstration of the scheme with muon testbeam data taken at the CERN Gamma Irradiation Facility are discussed.

Simulation predicts a high level of ionizing radiation in the ATLAS experimental hall during LHC operation. This radiation will act as a source of background signals to the four subsystems of the ATLAS muon detector. We present the performance of the Monitored Drift Tube detector (MDT) under these background conditions and discuss the consequences for the much higher background rates at SLHC with respect to tracking efficiency, resolution and readout bandwidth. For rates beyond the expected LHC levels, we discuss options to improve the performance of detector and electronics.

The ATLAS muon spectrometer uses three layers of precision drift-tube chambers to measure muon momenta accurately up to the TeV scale in an air-core toroid magnet system providing a field integral of 2.5 to 7 Tm. In order to achieve the required momentum resolution of better than 4% for transverse momenta below 400 GeV/c and of 10% at 1 TeV/c, the relative positions of the muon chambers must be known with 30 μm accuracy. A system of optical alignment sensors monitors relative movements of the chambers with a few micrometers accuracy. It is capable of measuring the relative chamber positions with an accuracy better than 30 μm after it has been calibrated with straight tracks. These will be provided by special runs with the magnets turned off. We present results of Monte-Carlo studies for the alignment with straight tracks recorded with proton-proton collisions at the LHC and cosmic muon data.

A 4-channel front-end electronics (4 × FEE) system for the muon drift tube in the ATLAS detector in the High-Luminosity LHC is presented. The overall channel architecture is optimized to reduce the power and area of the design. Each channel comprises a charge-sensitive preamplifier (CSP), shaper, discriminator and differential low-voltage signaling drivers. The proposed channel operates with a 5–100 fC input charge and exhibits a linear sensitivity of 8 mV/fC for the entire input charge range. The peaking time delay of the analog channel is 14.6 ns. At the output, the time representation of the input signal is provided in terms of the CMOS level and in scalable low-voltage signal (SLVS). The FEE consumes a current of 10.6 mA per channel from a single 1.2 V supply voltage. The full 4 × FEE design is realized in TSMC 65 nm CMOS technology and its die-area is 2 mm × 2 mm.

Abstract The Muon System of the ATLAS experiment at the CERN LHC will be upgraded for the high-luminosity phase of LHC to cope with higher rates and higher radiation levels. Most of the Muon-System on-detector electronics will be replaced. Commercial low-dropout voltage regulators have been considered as a robust, low-noise and economic solution to power distribution. These components should be selected based on their capability to comply to radiation requirements. We tested 7 different types of CMOS LDOs, monitoring online the output voltage of 10 samples of each type. Irradiations were performed in the Radial Channel 1 of the RSV TAPIRO fast neutron reactor at ENEA Casaccia (Rome), to test resistance to non-ionizing energy loss, and at the PIF 200 MeV proton beam at PSI (Villigen), to test for total ionizing dose and single event effects. The experimental setup and the results are presented and discussed in this paper.

Abstract A 4-channel front-end electronics chip in 65 nm CMOS technology (ASD65 nm) for muon drift tube chambers at high background counting rates in the ATLAS detector at High-Luminosity LHC and in future high-energy collider experiments is presented. Each channel of the ASD65 nm chip is a mixed-signal processing circuit consisting of a Charge Sensitive Preamplifier (CSP), a two-stage shaper, and a timing discriminator. The CSP exhibits a peaking time of 11 ns and a sensitivity of 1.1 mV/fC. The peaking time of the full analog chain is 14.6 ns. The minimum signal-to-noise ratio of the channel is 15 dB for the minimum input charge of 5 fC, and it rises to 40.5 dB for the maximum input charge of 100 fC. At the output, the time representation of input signal is provided in both, CMOS level as well as low-voltage-differential-signal. Each channel consumes a current of 10.6 mA from a single 1.2 V supply, and occupies an area of 0.235 mm 2 . The specified performance parameters of the ASD65 nm have been achieved for 60 pF parasitic capacitance of the detector connected the input terminal.

Resistive plate chambers (RPCs) with electrodes of high-pressure phenolic laminate and small gas gap widths down to 1 mm provide large area tracking at relatively low cost in combination with high rate capability and fast response with excellent time resolution of better than 500 ps. They are perfectly suited for experiments requiring sub-nanosecond time resolution and spatial resolution on the order of a few millimeters over large areas. Thin-gap RPCs will therefore be used for the upgrade of the barrel muon system of the ATLAS experiment at HL-LHC and are candidates for the instrumentation of future collider detectors and experiments searching for long-lived particles in experiments like ANUBIS. RPCs are also frequently used in large area cosmic ray detectors. The large demand for RPCs exceeds the presently available production capacities. At the same time, the requirements on mechanical precision, reliability and reproducibility for collider detectors have increased, especially with the reduced gas gap widths. Additional suppliers with industry-style quality assurance are therefore urgently needed.

Experiments like the ATLAS detector at the HL-LHC or detectors at future hadron colliders need muon detectors with excellent momentum resolution at the percent level up to the TeV scale both at the trigger and the offline reconstruction level. This requires muon tracking chambers with high spatial resolution even at the highest background fluxes. Drift-tube chambers are the most cost effective technology for the instrumentation of large-area muon systems providing the required high rate capability and three-dimensional spatial resolution. Thanks to the advances in analog and digital electronics, modern drift-tube chambers can be used in stand-alone mode up to the highest background rates providing event times and second coordinates without the necessity of additonal trigger chambers. New key developments in the integrated front-end electronics are fast baseline restoration of the shaped signal and picosecond time-to-digital converters for second coordinate measurement with double-sided read-out of the tubes. Self-triggered operation has become possible using modern high-performance FPGAs allowing for real-time pattern recognition and track reconstruction.

Abstract The front-end electronics of the ATLAS muon drift-tube chambers will be upgraded in the experiment’s phase-II upgrade to comply with the new trigger and read-out scheme at the HL-LHC. A new amplifier shaper discriminator chip was developed in 130 nm Global Foundries technology for this upgrade. A preproduction of 7500 chips was launched in 2019 and tested in 2020. The functionality of the chips, the test set-up and test procedure and results showing a yield of 93% are presented. The certification of the preproduction was followed by the production of 80,000 chips in fall 2020. The tests of a sample of 2949 preproduction and 1174 production chips gave a production yield &gt; 93%.

Muonic final states will provide clean signatures formany physics processes at the LHC. The two LHC experiments ATLAS and CMS will be able to identify muons with a high reconstruction efficiency above 96% and a high transverse momentum resolution better than 2% for transverse momenta below 400 GeV/c and about 10% at 1 TeV/c. The two experiments follow complentary concepts of muon detection. ATLAS has an instrumented air-toroid mangetic system serving as a stand-alone muon spectrometer. CMS relies on high bending power and momentum resolution in the inner detector, and uses an iron yoke to increase its magnetic field. The iron yoke is instrumented with chambers used for muon identification. Therefore, muon momenta can only be reconstructed with high precision by combining inner-detector information with the data from the muon chambers.

The High-Luminosity LHC will provide the unique opportunity to explore the nature of physics beyond the Standard Model of strong and electroweak interactions. Highly selective first level triggers are essential for the physics programme of the ATLAS experiment at the HL-LHC where the instantaneous luminosity will exceed the LHC Run 1 instantaneous luminosity by almost an order of magnitude. The ATLAS first level muon trigger rate is dominated by low momentum muons, selected due to the moderate momentum resolution of the resistive plate and thin gap trigger chambers. This limitation can be overcome by including the data of the precision muon drift tube (MDT) chambers in the first level trigger decision. This requires the fast continuous transfer of the MDT hits to the off-detector trigger logic and a fast track reconstruction algorithm performed in the trigger logic. In order to demonstrate the feasibility of reconstructing tracks in MDT chambers within the short available first-level trigger latency of about 3~$\mu$s we implemented a seeded Hough transform on the ARM Cortex A9 microprocessor of a Xilinx Zynq FPGA and studied its performance with test-beam data recorded in CERN's Gamma Irradiation Facility. We could show that by using the ARM processor's Neon Single Instruction Multiple Data Engine to carry out 4 floating point operations in parallel the challenging latency requirement can be matched.

Small diameter muon drift-tube (sMDT) chambers with 15 mm tube diameter provide excellent spatial resolution like the MDT chambers with 30 mm tube diameter used in the ATLAS muon spectrometer so far, but can be operated at ten times higher background rates and allow for the instrumentation of regions where MDT chambers do not fit in. In April 2014 two such chambers (called BME) have been installed at the bottom of the barrel middle layer of the muon spectrometer, followed in January 2016 by another 12 sMDT chambers (called BMG) inserted in the detector feet in the barrel middle layer. They are since then operational in ATLAS, increasing the acceptance for precision muon momentum measurement in all three chamber layers. An unprecedently high sense wire positioning accuracy of 5μm (rms) has been achieved. In the next long LHC shutdown 2019–2020, 16 new sMDT chambers (called BIS 78) will be installed in the barrel inner layer in the transition region to the endcaps in order to make room for the installation of new RPC muon trigger chambers which will reduce the accidental trigger rate in this region as required for operation at the high-luminosity upgrade of the LHC (HL-LHC). This is a pilot project for the complete replacement of the MDT chambers in the small azimuthal sectors of the barrel inner layer (called BIS 1-6) by integrated sMDT-RPC detectors in the long shutdown 2024–2026 for the upgrade to HL-LHC.

Single muon triggers are crucial for the physics programmes as hadron collider experiments. To be sensitive to electroweak processes, single muon triggers with transverse momentum thresholds down to 20 GeV and dimuon triggers with even lower thresholds are required. In order to keep the rates of these triggers at an acceptable level these triggers have to be highly selective, i.e. they must have small accidental trigger rates and sharp trigger turn-on curves. The muon systems of the LHC experiments and experiments at future colliders like FCC-hh will use two muon chamber systems for the muon trigger, fast trigger chambers like RPCs with coarse spatial resolution and much slower precision chambers like drift–tube chambers with high spatial resolution. The data of the trigger chambers are used to identify the bunch crossing in which the muon was created and for a rough momentum measurement while the precise measurements of the muon trajectory by the precision chambers are ideal for an accurate muon momentum measurement. A concept for the muon trigger of the baseline detector for the FCC-hh which exploits the precision measurements of drift–tube chambers is presented including the description and the test of a compact muon track reconstruction algorithm.

The High-Luminosity LHC will provide the unique opportunity to explore the nature of physics beyond the Standard Model. Highly selective first level triggers are essential for the physics programme of the ATLAS experiment at the HL-LHC, where the instantaneous luminosity will exceed the LHC design luminosity by almost an order of magnitude. The ATLAS first level muon trigger rate is dominated by low momentum muons, selected due to the moderate momentum resolution of the current system. This first level trigger limitation can be overcome by including data from the precision muon drift tube (MDT) chambers. This requires the fast continuous transfer of the MDT hits to the o -detector trigger logic and a fast track reconstruction algorithm performed in the trigger logic. The feasibility of this approach was studied with LHC collision data and simulated data. Two main options for the hardware implementation will be studied with demonstrators: an FPGA based option with an embedded ARM microprocessor and an associate memory chip base option. In this note the basic MDT trigger concept and the design of a demonstrator for the two hardware options are presented.

The analysis of the production of the Higgs boson at CERN's Large Hadron Collider provides sensitivity to the couplings of the Higgs boson to Standard Model particles and to contributions from physics beyond the Standard Model of electroweak interactions.In this note the Higgs boson production is investigated in the H → ZZ → 4 channel.A dataset of 79.8 fb -1 of 13 TeV pp collision data was used to study the Higgs boson production cross section differential in the transverse momentum of the Higgs boson and the number of jets in the final state and to measure the Higgs boson production modes in the simplified templated cross section framework.All results are in agreement with the predictions of the Standard Model prediction.The measurement of the off-shell production of Higgs bosons is also found to be compatible with Standard Model prediction.An upper limit on the off-shell signal strength of 3.8 and the natural width of the Higgs boson of 14.4 MeV could be set at 95% confidence level with 36.1 fb -1 of pp collision data.

The high luminosity and interaction rate expected from the planned High Luminosity-Large Hadron Collider (HL-LHC) upgrade require a replacement and improvement of the ATLAS Muon-Drift-Tube (MDT) read-out electronics.This paper presents a Phase Locked Loop (ePLL) intended to be used inside the improved Time-to-Digital Converter (TDC), which digitizes the arrival time and charge amplitude information.Starting from a 40 MHz input clock, the ePLL provides output clocks of 160 MHz and 320 MHz with a phase resolution of 11.25° and 22.5°, respectively.The prototype, integrated in 130 nm CMOS technology, has 0.02 mm 2 of area and 1.2V of supply voltage.

Single muon triggers are crucial for the physics programmes at hadron collider experiments. To keep the trigger rates reasonably low they must be highly selective. Muon systems at LHC experiments and at future colliders use two muon chamber system for triggering: fast trigger chambers to identify the bunch crossing and provide a coarse momentum estimation, and slower precision chambers, for precise measurements of the muon trajectory. A fast lightweight track finding algorithm, based on the Hough Transform and Linear Regression techniques, has been designed and implemented on a Zynq SoC device, reconstructing successfully muon tracks in a single trigger sector.

A Fast Tracker analog front end for small-diameter Muon Drift Tube (sMDT) detectors is hereby presented. The analog channel has been integrated in 28 nm CMOS technology and significantly improves state-of-the-art sMDT read-out systems thanks to a novel signal processing technique exploited to extract information from sMDT detectors speeding-up the processing time and to limit fake events detection. The main idea is to implement a fast reset of all continuous-time analog stages that occurs just after the charge (i.e. event) detection. This has two main advantages for sMDT read-out: fast processing and negligible signal corruption due to non-relevant pile-up signals. Nonetheless, the realization in 28nm bulk-CMOS technology implies challenges for analog design but advantages in terms of speed, area occupancy and radiation hardness. The proposed analog channel occupies 0.03 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> and consumes 1.9 mW from 1 V supply voltage.

Experiments at future hadron colliders like the High-Luminosity LHC or the proposed 100 TeV circular collider FCC-hh will provide a unique opportunity to explore the limits of the Standard Model of the strong and electroweak interactions and to search for physics beyond the Standard Model. Excellent muon identification and trigger capabilities will be crucial to exploit the experiments' physics potential. To achieve this goal the muon systems of these experiments will use both fast trigger chambers with nanosecond temporal, but poor spatial resolution and slower precision muon chambers with sub-micrometer spatial resolution for stand-alone momentum measurements. In this contribution a trigger system for the FCC-hh detector is introduced which uses thin-gap resistive plate chambers for bunch crossing identification and small diameter cylindrical drift tube chambers for an accurate momentum measurement both at trigger level and offline. Trigger algorithms and their VHDL implementation will be presented as well as the design of a hardware demonstrator employing modern high-performance FPGAs with more than 100 high-speed transceivers.

The High-Luminosity LHC will provide the unique opportunity to explore the nature of physics beyond the Standard Model of strong and electroweak interactions. Highly selective first level triggers are essential for the physics programme of the ATLAS experiment at the HL-LHC where the instantaneous luminosity will exceed the LHC Run 1 instantaneous luminosity by almost an order of magnitude. The ATLAS first level muon trigger rate is dominated by low momentum muons, selected due to the moderate momentum resolution of the resistive plate and thin gap trigger chambers. This limitation can be overcome by including the data of the precision muon drift tube (MDT) chambers in the first level trigger decision. This requires the fast continuous transfer of the MDT hits to the off-detector trigger logic and a fast track reconstruction algorithm performed in the trigger logic. In order to demonstrate the feasibility of reconstructing tracks in MDT chambers within the short available first-level trigger latency of about 3~$μ$s we implemented a seeded Hough transform on the ARM Cortex A9 microprocessor of a Xilinx Zynq FPGA and studied its performance with test-beam data recorded in CERN's Gamma Irradiation Facility. We could show that by using the ARM processor's Neon Single Instruction Multiple Data Engine to carry out 4 floating point operations in parallel the challenging latency requirement can be matched.

The ATLAS experiment at the Large Hadron CoIlider (LHC) at CERN is currently being assembled and to be ready to take data in 2007. In the barrel part of the muon spectrometer a toroidal air-core magnet is instrumented with three layers of monitored drift tube (MDT) chambers as precision tracking detectors. The installation of the muon detectors has started in January 2005. At the Max-Planck-Institut fur Physik and the Ludwig-Maximilians-University in Munich, 88 MDT chambers, each covering an area of 8 m/sup 2/, are being built for the outermost barrel region. The MDT chambers have to pass a series of stringent tests before installation to ensure their proper operation in the experiment. At the production site in Munich, these tests include gas tightness, high voltage stability and measurements of the noise rate, and the response to cosmic muons. In addition, the individual wire positions and electronic time offsets of the drift tubes are determined from the cosmic ray data. At CERN, a subset of the tests is repeated and the MDT chambers are integrated on a common support frame with resistive plate chambers (RPCs) of the trigger system. The results of the tests are stored in the ATLAS commissioning database and form an important basis for LHC data taking. We present the test methods and results, an overview on the integration work of the muon detectors and report on the experience with their installation in the ATLAS experiment.