T. Tuuva

The CMS detector at the CERN LHC features a silicon pixel detector as its innermost subdetector. The original CMS pixel detector has been replaced with an upgraded pixel system (CMS Phase-1 pixel detector) in the extended year-end technical stop of the LHC in 2016/2017. The upgraded CMS pixel detector is designed to cope with the higher instantaneous luminosities that have been achieved by the LHC after the upgrades to the accelerator during the first long shutdown in 2013–2014. Compared to the original pixel detector, the upgraded detector has a better tracking performance and lower mass with four barrel layers and three endcap disks on each side to provide hit coverage up to an absolute value of pseudorapidity of 2.5. This paper describes the design and construction of the CMS Phase-1 pixel detector as well as its performance from commissioning to early operation in collision data-taking.

This study evaluates differences in reversible (after relaxation) and irreversible compaction and the effect of compaction on the performance of three different ultrafiltration membranes. The evaluation is based on results from both off-line and on-line measurements of compaction. The on-line measurements were done with an ultrasonic time-domain reflectrometry (UTDR) tool with improved resolution compared to tools used in earlier studies. The results reveal that the regenerated cellulose membrane compacted significantly more than the tested polyethersulphone membranes. This dissimilarity originates from the different membrane materials used and from significant differences in the membrane structures. It is also found that measurements of membrane compaction, whether made on-line or off-line, are not predictive for membrane performance. For instance, compaction of the UH030 membrane was negligible but its permeability decrease and retention increase due to the compaction were significant. Compaction decreased the cut-off values of the 30 kDa membranes to lower than 8 kDa. The results thus indicate that the skin layers of the membranes compact significantly causing remarkable changes in membrane performance. Thickness changes occurring in the scale of skin layer thicknesses are out of the resolution limits of methods thus far available for monitoring of membrane compaction in real-time. Real-time measured information on compaction phenomena is further needed to be able to distinguish flux decrease caused by concentration polarization and the effects of reversible compaction.

The DELPHI Microvertex detector, which has been in operation since the start of the 1990 LEP run, consists of three layers of silicon microstrip detectors at average radii of 6.3, 9.0 and 11.0 cm. The 73728 readout strips, oriented along the beam, have a total active area of 0.42 m2. The strip pitch is 25 μm and every other strip is read out by low power charge amplifiers, giving a signal to noise ratio of 15:1 for minimum ionizing particles. On-line zero suppression results in an average data size of 4 kbyte for Z0 events. After a mechanical survey and an alignment with tracks, the impact parameter uncertainty as determined from hadronic Z0 decays is well described by (69pt)2 + 242 μm, with pt in GeV/c. For the 45 GeV/c tracks from Z0 → μ− decays we find an uncertainty of 21 μm for the impact parameter, which corresponds to a precision of 8 μm per point. The stability during the run is monitored using light spots and capacitive probes. An analysis of tracks through sector overlaps provides an additional check of the stability. The same analysis also results in a value of 6 μm for the intrinsic precision of the detector.

The silicon strip microvertex detector of the DELPHI experiment at the CERN LEP collider has been recently upgraded from two coordinates (RΦ only) to three coordinates reconstruction (RΦ and z). The new Microvertex detector consists of 125 952 readout channels, and uses novel techniques to obtain the third coordinate. These include the use of AC coupled double sided silicon detectors with strips orthogonal to each other on opposite sides of the detector wafer. The routing of signals from the z strips to the end of the detector modules is done with a second metal layer on the detector surface, thus keeping the material in the sensitive area to a minimum. Pairs of wafers are daisy chained, with the wafers within each pair flipped with respect to each other in order to minimize the load capacitance on the readout amplifiers. The design of the detector and its various components are described. Results on the performance of the new detector are presented, with special emphasis on alignment, intrinsic precision and impact parameter resolution. The new detector has been taking data since spring of 1994, performing up to design specifications.

A silicon microstrip detector with capacitive coupling of the diode strips to the metallization and with individual polysilicon resistors to each diode has been developed. The detector was tested in a minimum ionizing particle beam showing a performance similar to conventional strip detectors and a spatial resolution of 3.5 μm. Capacitive coupling allows the decoupling of the leakage current from the input to the charge sensitive preamplifier especially in the case of LSI electronics.

The upgrade of the LHC to the High-Luminosity LHC (HL-LHC) is expected to increase the LHC design luminosity by an order of magnitude. This will require silicon tracking detectors with a significantly higher radiation hardness. The CMS Tracker Collaboration has conducted an irradiation and measurement campaign to identify suitable silicon sensor materials and strip designs for the future outer tracker at the CMS experiment. Based on these results, the collaboration has chosen to use n-in-p type silicon sensors and focus further investigations on the optimization of that sensor type. This paper describes the main measurement results and conclusions that motivated this decision.

Compaction of a polymeric membrane results in a denser membrane structure with increased hydrodynamic resistance, which may positively affect the retention factor. This raises the question of whether membrane compaction could be a cheap and simple way to enhance membrane performance. In this study, compaction and retention data of four different commercial polyethersulphone and regenerated cellulose membranes were examined to gain insight into how membrane retentions could be improved with compaction at different temperatures. Although there was enormous variation in both the reversible and irreversible compaction of the membranes tested, retention in all membranes clearly increased after compression under 7 bar and 50 or 70 °C conditions. For instance, polyethylene glycol (PEG) (8 kg/mol) retention of a 30 kg/mol membrane increased even by 22 percentage points, up to 97%. This study demonstrates that it is possible to easily modify retention values of commercially available membranes, thereby increasing their usability in different applications.

Results are presented from a test in the CERN SPS North Area of a prototype of the DELPHI microvertex detector. Full-sized modules built up from prototype ac-coupled detectors and VLSI readout electronics were used. The spatial resolution of the detectors equipped with prototype VLSI chips was measured to be 6.5 μm. The system aspects, including the readout, were found to work well. Extrapolating to the final components we expect to achieve a measurement precision of 5 μm with the DELPHI microvertex detector.

A silicon microstrip detector has been developed with 50- mu m-pitch strips on both the p- and n-side, using the principle of capacitive coupling between p/sup +/ diode strips (respectively, n/sup +/ strips) and the metallization strips which connect to the front-end preamplifiers. The detector is biased on both sides via polysilicon resistors connecting each p/sup +/ or n/sup +/ line to a common bias bus. To allow ohmic separation at the n-side, the accumulation layer of electrons has to be disrupted between the n/sup +/ strips. This has been achieved in three different ways: by separate polysilicon lines on thick oxide between two adjacent n/sup +/ lines to break the conducting accumulation layer by externally induced field depletion or by using the metal lines of the n/sup +/ strips on thick oxide or on thin oxide. Results on 20*20-mm/sup 2/ test devices are presented. A preliminary analysis of the spatial resolution gives sigma =16 mu m on both sides. These results demonstrate that double-sided readout Si strip detectors can be used for experiments where spatial resolution in the 10 mu m range is needed.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

The degradation of signal in silicon sensors is studied under conditions expected at the CERN High-Luminosity LHC. 200 μm thick n-type silicon sensors are irradiated with protons of different energies to fluences of up to 3 · 1015 neq/cm2. Pulsed red laser light with a wavelength of 672 nm is used to generate electron-hole pairs in the sensors. The induced signals are used to determine the charge collection efficiencies separately for electrons and holes drifting through the sensor. The effective trapping rates are extracted by comparing the results to simulation. The electric field is simulated using Synopsys device simulation assuming two effective defects. The generation and drift of charge carriers are simulated in an independent simulation based on PixelAV. The effective trapping rates are determined from the measured charge collection efficiencies and the simulated and measured time-resolved current pulses are compared. The effective trapping rates determined for both electrons and holes are about 50% smaller than those obtained using standard extrapolations of studies at low fluences and suggest an improved tracker performance over initial expectations.

The design and first results from double-sided silicon microstrip detectors designed for use in the DELPHI experiment at LEP are presented. The detectors are AC-coupled on both the n- and p-side. A novel readout scheme using a second metal layer has been implemented, allowing the readout of both coordinates on the same edge of the detector. The detectors have been tested in a high energy beam at the CERN SPS. Results on spatial resolution, pulse-height correlation and charge division are presented. The spatial resolution of the n-side has been measured as a function of the beam particle incident angle from 0 to 60°.

A new CMS tracker detector will be installed for operation at the High Luminosity LHC (HL-LHC). This detector comprises modules with two closely spaced parallel sensor plates and front-end ASICs capable of transmitting tracking information to the CMS Level-1 (L1) trigger at the 40 MHz beam crossing rate. The inclusion of tracking information in the L1 trigger decision will be essential for selecting events of interest efficiently at the HL-LHC. The CMS Binary Chip (CBC) has been designed to read out and correlate hits from pairs of tracker sensors, forming so-called track stubs. For the first time, a prototype irradiated module and a full-sized module, both equipped with the version 2 of the CBC, have been operated in test beam facilities. The efficiency of the stub finding logic of the modules for various angles of incidence has been studied. The ability of the modules to reject tracks with transverse momentum less than 2 GeV has been demonstrated. For modules built with irradiated sensors, no significant drop in the stub finding performance has been observed. Results from the beam tests are described in this paper.

To cope with the challenging environment of the planned high luminosity upgrade of the Large Hadron Collider (HL-LHC), scheduled to start operation in 2029, CMS will replace its entire tracking system. The requirements for the tracker are largely determined by the long operation time of 10 years with an instantaneous peak luminosity of up to 7.5 × 1034 cm−2 s−1 in the ultimate performance scenario. Depending on the radial distance from the interaction point, the silicon sensors will receive a particle fluence corresponding to a non-ionising energy loss of up to Φeq= 3.5 × 1016 cm−2. This paper focuses on planar pixel sensor design and qualification up to a fluence of Φeq = 1.4 × 1016 cm−2.For the development of appropriate planar pixel sensors an R&D program was initiated, which includes n+-p sensors on 150 mm (6”) wafers with an active thickness of 150 µm with pixel sizes of 100×25 µm2 and 50×50 µm2 manufactured by Hamamatsu Photonics K.K. (HPK). Single chip modules with ROC4Sens and RD53A readout chips were made. Irradiation with protons and neutrons, as well was an extensive test beam campaign at DESY were carried out. This paper presents the investigation of various assemblies mainly with ROC4Sens readout chips. It demonstrates that multiple designs fulfil the requirements in terms of breakdown voltage, leakage current and efficiency. The single point resolution for 50×50 µm2 pixels is measured as 4.0 µm for non-irradiated samples, and 6.3 µm after irradiation to Φeq = 7.2 × 1015 cm−2.

Abstract The Large Hadron Collider at CERN will undergo an upgrade in order to increase its luminosity to 7.5 × 10 34 cm -2 s -1 . The increased luminosity during this High-Luminosity running phase, starting around 2029, means a higher rate of proton-proton interactions, hence a larger ionizing dose and particle fluence for the detectors. The current tracking system of the CMS experiment will be fully replaced in order to cope with the new operating conditions. Prototype planar pixel sensors for the CMS Inner Tracker with square 50 μm × 50 μm and rectangular 100 μm × 25 μm pixels read out by the RD53A chip were characterized in the lab and at the DESY-II testbeam facility in order to identify designs that meet the requirements of CMS during the High-Luminosity running phase. A spatial resolution of approximately 3.4 μm (2 μm) is obtained using the modules with 50 μm × 50 μm (100 μm × 25 μm) pixels at the optimal angle of incidence before irradiation. After irradiation to a 1 MeV neutron equivalent fluence of Φ eq = 5.3 × 10 15 cm -2 , a resolution of 9.4 μm is achieved at a bias voltage of 800 V using a module with 50 μm × 50 μm pixel size. All modules retain a hit efficiency in excess of 99% after irradiation to fluences up to 2.1 × 10 16 cm -2 . Further studies of the electrical properties of the modules, especially crosstalk, are also presented in this paper.

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

Abstract Silicon edgeless detectors represent a novel type of detector that are being developed for close-to-beam applications in high-energy physics and for large-scale tiled 1D and 2D arrays used in radiation imaging. In this work, the electric field and potential distributions on the device cut side, key factors in detector performance, have been investigated using two methods—the Conductive Microprobe Technique and the Scanning Transient Current Technique. It has been found that the behaviour of the potential distribution at the edge indicates a significant presence of positively charged states, with the charge density changing with the applied voltage. This work will predict, to a first approximation, the trend of the electric field at the edge of these devices after irradiation to high fluences. This prediction will provide key inputs in the development of edgeless radiation hard detectors.

A beam telescope providing precision track measurements as reference for other detectors has been upgraded in the CERN H2 test beam. The apparatus was completely rebuilt from the detector wafers and front-end electronics to the data acquisition system. The new detector setup consists of eight 5.6×5.6cm2 sized DC coupled silicon microstrip detectors. Typical position resolution values of about 7.5μm were measured. Details of the setup are described and results from the recent beam tests are reported.

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

Abstract The CMS Inner Tracker, made of silicon pixel modules, will be entirely replaced prior to the start of the High Luminosity LHC period. One of the crucial components of the new Inner Tracker system is the readout chip, being developed by the RD53 Collaboration, and in particular its analogue front-end, which receives the signal from the sensor and digitizes it. Three different analogue front-ends (Synchronous, Linear, and Differential) were designed and implemented in the RD53A demonstrator chip. A dedicated evaluation program was carried out to select the most suitable design to build a radiation tolerant pixel detector able to sustain high particle rates with high efficiency and a small fraction of spurious pixel hits. The test results showed that all three analogue front-ends presented strong points, but also limitations. The Differential front-end demonstrated very low noise, but the threshold tuning became problematic after irradiation. Moreover, a saturation in the preamplifier feedback loop affected the return of the signal to baseline and thus increased the dead time. The Synchronous front-end showed very good timing performance, but also higher noise. For the Linear front-end all of the parameters were within specification, although this design had the largest time walk. This limitation was addressed and mitigated in an improved design. The analysis of the advantages and disadvantages of the three front-ends in the context of the CMS Inner Tracker operation requirements led to the selection of the improved design Linear front-end for integration in the final CMS readout chip.

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

The silicon strip microvertex detector for the DELPHI experiment at LEP is presented. It consists of two cylindrical layers with a total of 165 888 strips. The design parameters of the final project are described. The microstrip counters have a pitch of 16.6 μm, and are read out every 50 μm using the capacitive charge division method. The electronics used is the Microplex chip, an NMOS integrated circuit, which provides 128 channels of low noise charge sensitive amplifiers with multiplexed analog output. Results of signal-to-noise ratio from beam tests on prototype detectors are given and discussed.

Abstract Double-sided silicon strip detectors with integrated coupling capacitors and polysilicon resistors have been processed on a 100 mm wafer. A detector with an active area of 19 × 19 mm 2 was connected to LSI readout electronics and tested. The strip pitch of the detector is 25 μm on the p-side and 50 μm on the n-side. The readout pitch is 50 μm on both sides. The number of readout strips is 774 and the total number of strips is 1161. On the p-side a signal-to-noise of 35 has been measured using a 90 Sr β-source. The n-side has been studied using a laser.

An ultrasonic sensor design with sonic velocity compensation is developed to improve the accuracy of distance measurement in membrane modules. High accuracy real-time distance measurements are needed in membrane fouling and compaction studies. The benefits of the sonic velocity compensation with a reference transducer are compared to the sonic velocity calculated with the measured temperature and pressure using the model by Belogol’skii, Sekoyan et al. In the experiments the temperature was changed from 25 to 60 °C at pressures of 0.1, 0.3 and 0.5 MPa. The set measurement distance was 17.8 mm. Distance measurements with sonic velocity compensation were over ten times more accurate than the ones calculated based on the model. Using the reference transducer measured sonic velocity, the standard deviations for the distance measurements varied from 0.6 to 2.0 µm, while using the calculated sonic velocity the standard deviations were 21–39 µm. In industrial liquors, not only the temperature and the pressure, which were studied in this paper, but also the properties of the filtered solution, such as solute concentration, density, viscosity, etc., may vary greatly, leading to inaccuracy in the use of the Belogol’skii, Sekoyan et al. model. Therefore, calibration of the sonic velocity with reference transducers is needed for accurate distance measurements.

A new pixel detector for the CMS experiment was built in order to cope with the instantaneous luminosities anticipated for the Phase~I Upgrade of the LHC. The new CMS pixel detector provides four-hit tracking with a reduced material budget as well as new cooling and powering schemes. A new front-end readout chip mitigates buffering and bandwidth limitations, and allows operation at low comparator thresholds. In this paper, comprehensive test beam studies are presented, which have been conducted to verify the design and to quantify the performance of the new detector assemblies in terms of tracking efficiency and spatial resolution. Under optimal conditions, the tracking efficiency is $99.95\pm0.05\,\%$, while the intrinsic spatial resolutions are $4.80\pm0.25\,\mu \mathrm{m}$ and $7.99\pm0.21\,\mu \mathrm{m}$ along the $100\,\mu \mathrm{m}$ and $150\,\mu \mathrm{m}$ pixel pitch, respectively. The findings are compared to a detailed Monte Carlo simulation of the pixel detector and good agreement is found.

During the high-luminosity phase of the LHC (HL-LHC), planned to start in 2027, the accelerator is expected to deliver an instantaneous peak luminosity of up to 7.5×1034 cm−2 s−1. A total integrated luminosity of 0300 or even 0400 fb−1 is foreseen to be delivered to the general purpose detectors ATLAS and CMS over a decade, thereby increasing the discovery potential of the LHC experiments significantly. The CMS detector will undergo a major upgrade for the HL-LHC, with entirely new tracking detectors consisting of an Outer Tracker and Inner Tracker. However, the new tracking system will be exposed to a significantly higher radiation than the current tracker, requiring new radiation-hard sensors. CMS initiated an extensive irradiation and measurement campaign starting in 2009 to systematically compare the properties of different silicon materials and design choices for the Outer Tracker sensors. Several test structures and sensors were designed and implemented on 18 different combinations of wafer materials, thicknesses, and production technologies. The devices were electrically characterized before and after irradiation with neutrons, and with protons of different energies, with fluences corresponding to those expected at different radii of the CMS Outer Tracker after 0300 fb−1. The tests performed include studies with β sources, lasers, and beam scans. This paper compares the performance of different options for the HL-LHC silicon sensors with a focus on silicon bulk material and thickness.

A planar process for manufacturing large silicon detectors on a 100 mm wafer has been developed. Several oxidation and annealing temperatures were studied in order to optimize detector performance. A strip detector with an active area of 32 × 58 mm2 together with various single detector diodes were processed and tested. The 1280 strip detector with 25 μm strip and readout pitch was connected to multiplexing LSI electronics and tested with tracks from a 90Sr beta source. The most probable signal pulse height was found to be 14 times the σnoise of any individual channel.

VFAT3 is the front-end ASIC designed specifically for the readout of GEM detectors within the CMS experiment during the high luminosity phase of the LHC at CERN. This paper presents the analog and digital design plus the measured functional and characterization results. Key design goals were optimization to GEM charge characteristics maximizing signal to noise, timing resolution and operation at high particle rate. There are 128 front-end channels comprising preamplifier, shaper and constant fraction discriminator (CFD). Features include programmable polarity (for use with gaseous MPGD or silicon detectors), programmable gain (for linearity 9.5 fC, 28 fC and 55 fC) and programmable shaping times (15 ns, 25 ns, 36 ns and 45 ns), plus the CFD reducing time walk to less than 0.4 ns within 3 fC to 30 fC of input charge, optimizing timing resolution. An internal calibration circuit allows calibration of each channel with "GEM like" or "Silicon like" input pulses, each having programmable amplitude, polarity and phase. The ENC measures 620 e + 33 e/pF in high gain. The hit rate capability is demonstrated to 2 MHz per channel. VFAT3 has 2 output paths; the first (Trigger Path) provides hit information for every LHC clock cycle. The second (Data Path) provides data packets upon receipt of a trigger, each data packet contains hit information and time stamps. The chip can operate with trigger latencies up to 25.6 μs and is capable of receiving consecutive triggers. VFAT3 can operate with up to 2 MHz trigger rate in default mode and has data packet zero suppression capabilities to go beyond this rate. An internal dedicated Comm-Port allows communication to and from the chip. Additional features include channel input protection, internal/external temperature measurement and design for a radiation environment. The design and measurements presented demonstrate the VFAT3 capability as a complete binary front-end readout ASIC optimized for GEM detectors in the high luminosity LHC.

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

Abstract Capacitively coupled Si strip detectors with readout on both the p-side and the n-side have been developed. A novel scheme to separate strips ohmically on the n-side by means of field depletion via a suitable potential applied to the readout strips has been successfully demonstrated. Results on the spatial resolution of these detectors for both sides measured in a high energy beam are presented. The spatial resolution of the n-side has been measured at different incident angles of the beam tracks with respect to a vertical plane through the n + strips at 0°, 20° and 40°.

Inelastic nuclear collisions of hadrons incident on silicon sensors can generate secondary highly ionising particles (HIPs) and deposit as much energy within the sensor bulk as several hundred minimum ionising particles. The large signals generated by these ‘HIP events’ can momentarily saturate the APV25 front-end readout chip for the silicon strip tracker (SST) sub-detector of the compact muon solenoid (CMS) experiment, resulting in deadtime in the detector readout system. This paper presents studies of this phenomenon through simulation, laboratory measurements and dedicated beam tests. A proposed change to a front-end component to reduce the APV25 sensitivity to HIP events is also examined. The results are used to infer the expected effect on the performance of the CMS SST at the future large hadron collider. The induced inefficiencies are at the percent level and will have a negligible effect on the physics performance of the SST.

The high luminosity upgrade of the Large Hadron Collider, foreseen for 2026, necessitates the replacement of the CMS experiment’s silicon tracker. The innermost layer of the new pixel detector will be exposed to severe radiation, corresponding to a 1 MeV neutron equivalent fluence of up to $$\Phi _{eq} = 2 \times 10^{16}$$ cm $$^{-2}$$ , and an ionising dose of $${\approx } 5$$ MGy after an integrated luminosity of 3000 fb $$^{-1}$$ . Thin, planar silicon sensors are good candidates for this application, since the degradation of the signal produced by traversing particles is less severe than for thicker devices. In this paper, the results obtained from the characterisation of 100 and 200 $$\upmu $$ m thick p-bulk pad diodes and strip sensors irradiated up to fluences of $$\Phi _{eq} = 1.3 \times 10^{16}$$ cm $$^{-2}$$ are shown.

Membrane fouling, where unwanted particles accumulate on the membrane surface and reduce its permeability, causes problems in membrane filtration processes. With ultrasonic time-domain reflectometry (UTDR) it is possible to measure the extent of membrane fouling and hence take actions to minimize it. However, the usability of UTDR is very limited to constant filtration conditions if the sonic velocity, which has a great impact on UTDR measurement accuracy, is unknown. With a reference transducer the actual sonic velocity can be measured. This requires another transducer to be installed in the module, where there may be only limited space or the module dimensions may not be suitable for the reference transducer. A double transducer described in this study eliminates the need for a separate reference transducer because in the double transducer the reference measurement is included in the design of the transducer holder. Two sensors in the same holder require less space. Other advantage is that the double transducer can be placed near the measurement target and hence the local sonic velocity can be determined.

This paper presents the VFAT3 Comm-Port (V3CP), which offers a single port for all communication to and from a front-end ASIC within the HL-LHC environment. This includes synchronization to the LHC clock, slow control communication, the execution of fast control commands and the readout of data.

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

Abstract Progress in the construction of the DELPHI silicon microstrip vertex detector is described and results obtained for the various components are presented. Problems related to the design, construction and survey of a system capable of maintaining in a collider environment the resolution achievable by microstrip detectors are discussed. Finally, some plans for the future are also reported.

A silicon microstrip detector has been developed with capacitive coupling of the diode strips to the metallization and with polysilicon bias resistors to each diode. It allows the decoupling of the leakage current from the input to the charge-sensitive amplifier. Results are given on the coupling capacity and the breakdown voltage as well as on the polysilicon line resistance. It is found that the coupling capacitance, varying between 25 pF and 80 pF as a function of the oxide thickness, is large enough to avoid capacitance signal losses to the backplane. The 200-nm-thick silicon oxide withstands a potential difference of 100 V or more, thus allowing the operation of the detector with the metal strips and backplane at a ground potential and the bias voltage applied to the diodes.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

This paper describes the work done in relation to putting a relatively high volume HEP readout electronics module into production. The main features of this fibre optic data transfer board designed for the Compact Muon Solenoid (CMS) Resistive Plate Chamber (RPC) detector are described, concentrating on how the final implementation was arrived at. An automated production testing method is introduced, and results are given of its efficiency in finding faulty boards and localising the faults.

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

In this contribution we will report on the progress of the design of the readout and data acquisition system being developed for triple-GEM detectors which will be installed in the forward region (1.5 < |η| < 2.2) of the CMS muon spectrometer during the 2nd long shutdown of the LHC, expected in the period 2017–2018. The system will be designed to take full advantage of current generic developments introduced for the LHC upgrades. The current design is based on the use of CERN GLIB boards hosted in micro-TCA crates for the off-detector electronics and the Versatile Link with the GBT chipset to link the front-end electronics to the GLIB boards. In this contribution we will describe the physics goals, the hardware architectures and report on the expected performance of the CMS GEM readout system, including preliminary timing resolution simulations.

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

Detectors with n-type silicon with an n+-type guard ring were investigated. In the present work, a new p+/n/n+ detector structure with an n+ guard ring is described. The guard ring is placed at the edge of the detector. The detector depletion region extends also sideways, allowing for signal collection very close to the n-guard ring. In this kind of detector structure, the dead space of the detector is minimized to be only below the guard ring. This is proved by simulations done using Silvaco/ATLAS software.

In 2017 a new pixel detector was installed in the CMS detector. This so-called Phase-1 pixel detector features four barrel layers in the central region and three disks per end in the forward regions. The upgraded pixel detector requires an upgraded data acquisition (DAQ) system to accept a new data format and larger event sizes. A new DAQ and control system has been developed based on a combination of custom and commercial microTCA parts. Custom mezzanine cards on standard carrier cards provide a front-end driver for readout, and two types of front-end controller for configuration and the distribution of clock and trigger signals. Before the installation of the detector the DAQ system underwent a series of integration tests, including readout of the pilot pixel detector, which was constructed with prototype Phase-1 electronics and operated in CMS from 2015 to 2016, quality assurance of the CMS Phase-1 detector during its assembly, and testing with the CMS Central DAQ. This paper describes the Phase-1 pixel DAQ and control system, along with the integration tests and results. A description of the operational experience and performance in data taking is included.

We present the current status of our project of developing a photon counting detector for medical imaging. An example motivation lays in producing a monitoring and dosimetry device for boron neutron capture therapy, currently not commercially available. Our approach combines in-house developed detectors based on cadmium telluride or thick silicon with readout chip technology developed for particle physics experiments at CERN. Here we describe the manufacturing process of our sensors as well as the processing steps for the assembly of first prototypes. The prototypes use currently the PSI46digV2.1-r readout chip. The accompanying readout electronics chain that was used for first measurements will also be discussed. Finally we present an advanced algorithm developed by us for image reconstruction using such photon counting detectors with focus on boron neutron capture therapy. This work is conducted within a consortium of Finnish research groups from Helsinki Institute of Physics, Aalto University, Lappeenranta-Lahti University of Technology LUT and Radiation and Nuclear Safety Authority (STUK) under the RADDESS program of Academy of Finland.

Abstract During the operation of the CMS experiment at the High-Luminosity LHC the silicon sensors of the Phase-2 Outer Tracker will be exposed to radiation levels that could potentially deteriorate their performance. Previous studies had determined that planar float zone silicon with n-doped strips on a p-doped substrate was preferred over p-doped strips on an n-doped substrate. The last step in evaluating the optimal design for the mass production of about 200 m 2 of silicon sensors was to compare sensors of baseline thickness (about 300 μm) to thinned sensors (about 240 μm), which promised several benefits at high radiation levels because of the higher electric fields at the same bias voltage. This study provides a direct comparison of these two thicknesses in terms of sensor characteristics as well as charge collection and hit efficiency for fluences up to 1.5 × 10 15 n eq /cm 2 . The measurement results demonstrate that sensors with about 300 μm thickness will ensure excellent tracking performance even at the highest considered fluence levels expected for the Phase-2 Outer Tracker.

Abstract A capacitively coupled silicon strip detector with 50 μm readout pitch has been tested in a pion beam at CERN. The spatial resolution of the detector equipped with LSI readout chips was 4.9 μm and the most probable signal-to-single-channel noise ratio was 31.

This paper presents design, fabrication and the first characterization of the new 3D stripixel detector. The device has dual-column electrodes (both n+- and p+-type) arranged in a quincunx configuration and processed in a single-sided process on n-type silicon bulk. Double-metal technology allows to connect the electrodes by two sets of perpendicular strips providing a X-Y projective read-out. The design of the sensor has been optimized with the use of TCAD Sentaurus simulations. TCT measurements were performed to study the active area of the detector. Finally, 2D position sensitivity was investigated reconstructing the position of a laser beam within a 80 × 80 μm2 pixel, defined by two neighbouring p+-type strips crossing two neighbouring n+-type strips.

Abstract The Large Hadron Collider (LHC) at CERN will undergo major upgrades to increase the instantaneous luminosity up to 5–7.5×10 34 cm -2 s -1 . This High Luminosity upgrade of the LHC (HL-LHC) will deliver a total of 3000–4000 fb -1 of proton-proton collisions at a center-of-mass energy of 13–14 TeV. To cope with these challenging environmental conditions, the strip tracker of the CMS experiment will be upgraded using modules with two closely-spaced silicon sensors to provide information to include tracking in the Level-1 trigger selection. This paper describes the performance, in a test beam experiment, of the first prototype module based on the final version of the CMS Binary Chip front-end ASIC before and after the module was irradiated with neutrons. Results demonstrate that the prototype module satisfies the requirements, providing efficient tracking information, after being irradiated with a total fluence comparable to the one expected through the lifetime of the experiment.

This paper describes the main achievements in the development of radiation resistant silicon detectors to be used in the CMS tracker. After a general description of the basic requirements for the operation of large semiconductor systems in the LHC environment, the issue of radiation resistance is discussed in detail. Advantages and disadvantages of the different technological options are presented for comparison. Laboratory measurements and test beam data are used to check the performance of several series of prototypes fabricated by different companies. The expected performance of the final detector modules are presented together with preliminary test beam results on system prototypes.

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

Si strip detectors with integrated coupling capacitors between diode and metallization and with separate bias resistors for each strip have been exposed to ionising radiation. Results from measurements of detector response before and after irradiation are presented.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

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

VFAT3 is the last version of a family of multichannel trigger and tracking ASICs designed for the upgrade of the CMS experiment in the LHC. The chip has been developed to provide fast trigger information from the readout of gas particle detectors improving the resolution of the time measurement. The VFAT3 architecture comprises 128 analog channels, each one composed by a low noise and low power charge sensitive amplifier, shaper and constant fraction discriminator. The comparator output is synchronized with the LHC clock and sent both to a fixed latency path for trigger signal generation and to a variable latency path for storage and readout. The front-end amplifier is programmable in terms of gain and pulse shaping time, in order to adapt it to a wide range of gaseous detectors as well as silicon detectors. The chip also comprises a programmable calibration system that can provide both voltage and current pulses. There are also two internal 10 bit ADCs for the monitoring of the internal bias references. The digital logic provides trigger generation, digital data tagging and storage, data formatting and data packet transmission with error protection on 320Mbps e-link. The digital design is triplicated in order to improve the radiation hardness of the system. A first run of the chip of 9.1×6.1mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> in 130nm technology node has been submitted and produced. Chip architecture, measurements and characterization of the calibration, bias and monitoring system will be shown.

Results are presented from a beam test in the CERN SPS North Area of a silicon strip detector. The detector is directly coupled and has an active area of 32 × 58 mm and a strip pitch of 25 μm. It is processed on a 100 mm wafer. Spatial resolution of the detector equipped with LSI readout chips was measured to be 3.9 μm and the most probable signal to single channel noise ratio was 20.

Based on the results of capacitance–voltage measurements and transient current technique, it was earlier deduced that the n-type bulk of float zone silicon radiation detectors changes type in heavy irradiation. This paper describes the results of measuring the voltages and electric fields with a scanning electron microscope using the voltage–contrast effect, inside radiation detectors that were irradiated with 10 MeV protons with several fluences. The results confirm the earlier observations and give more accuracy to the electric field measurements.

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

Abstract The Short Strip ASIC (SSA) is one of the four front-end chips designed for the upgrade of the CMS Outer Tracker for the High Luminosity LHC. Together with the Macro-Pixel ASIC (MPA) it will instrument modules containing a strip and a macro-pixel sensor stacked on top of each other. The SSA provides both full readout of the strip hit information when triggered, and, together with the MPA, correlated clusters called stubs from the two sensors for use by the CMS Level-1 (L1) trigger system. Results from the first prototype module consisting of a sensor and two SSA chips are presented. The prototype module has been characterized at the Fermilab Test Beam Facility using a 120 GeV proton beam.

We have developed a novel detector concept based on Modified Internal Gate Field Effect Transistor (MIGFET) wherein a buried Modified Internal Gate (MIG) is implanted underneath a channel of a FET. In between the MIG and the channel of the FET there is a depleted semiconductor material forming a potential barrier between charges in the channel and similar type signal charges located in the MIG. The signal charges in the MIG have a measurable effect on the conductance of the channel. In this paper a double MIGFET pixel is investigated comprising two MIGFETs. By transferring the signal charges between the two MIGs Non-Destructive Correlated Double Sampling Readout (NDCDSR) is enabled. The proposed MIG radiation detector suits particularly well for low-light-level imaging, X-ray spectroscopy, as well as synchrotron and X-ray Free Electron Laser (XFEL) facilities. The reason for the excellent X-ray detection performance stems from the fact that interface related issues can be considerably mitigated since interface generated dark noise can be completely avoided and interface generated 1/f and Random Telegraph Signal (RTS) noise can be considerably reduced due to a deep buried channel readout configuration. Electrical parameters of the double MIGFET pixel have been evaluated by 3D TCAD simulation study. Simulation results show the absence of interface generated dark noise, significantly reduced interface generated 1/f and RTS noise, well performing NDCDSR operation, and blooming protection due to an inherent vertical anti-blooming structure. In addition, the backside illuminated thick fully depleted pixel design provides a homogeneous radiation entry window, low crosstalk due to lack of diffusion, and good quantum efficiency for low energy X-rays and NIR light. These facts result in excellent Signal-to-Noise Ratio (SNR) and very low crosstalk enabling thus excellent X-ray energy and spatial resolution. The simulation demonstrates the charge to current conversion gain for source current readout to be 1.4 nA/e.

Developed for use with triple GEM detectors, the GEM Electronic Board (GEB) forms a crucial part of the electronics readout system being developed as part of the CMS muon upgrade program. The objective of the GEB is threefold; to provide stable powering and ground for the VFAT3 front ends, to enable high-speed communication between 24 VFAT3 front ends and an optohybrid, and to shield the GEM detector from electromagnetic interference. The paper describes the concept and design of a large-size GEB in detail, highlighting the challenges in terms of design and feasibility of this deceptively difficult system component.

The Silicon Drift Detectors (SDDs) have replaced simple diodes in demanding X-ray fluorescence applications like in element analysers capable of detecting light elements. The reason for this is that with similar collection area the SDDs have a much smaller output capacitance than diodes due to a much smaller anode size. Thus the SDDs provide much better Signal to Noise Ratio (SNR) at smaller signal levels than diodes. The small capacitance in SDDs is achieved by placing concentric rings around a miniature sized anode. These rings are biased such that inside the SDD's fully depleted bulk a radial electric field component is established guiding signal charges towards the anode.

Abstract Silicon strip detectors with double-sided readout have been designed and processed on 100 mm silicon wafers. Detectors with integrated coupling capacitors and polysilicon bias resistors were tested by static electrical measurements, laser illumination and with tracks from a 90 Sr source. Strip separation on the detector n-side has been achieved by the use of capacitively coupled readout electrodes as field-plates. Interstrip resistance of > 10 Mω has been measured in all detector designs. Measurements with 90 Sr tracks show S/N = 21 on the detector p-side and S/N = 18 on the n-side.

A two-dimensional single sided Si strip detector using cross connected short strips interleaved with long strips has been designed. In the design, the z coordinate (along the strips) can be measured by finding the crossing point of the strips. No sacrifice is necessary on the r phi coordinate resolution in the design.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

An electronics module has been designed and tested for the CMS RPC detector readout. The module consists of twelve sub-blocks, each of which receives an optical signal at 1.6 GHz, converts it into electronic form for the splitting process and sends it forth to two or four destinations in optical form. It is a critical part in the trigger system of the experiment. Details of the design are presented, as well as test results confirming that the splitter fulfils all system requirements.

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

A study of a possible layout of a Silicon tracker has been done. The design is based on simulations done in the context of the Compact Muon Solenoid (CMS) detector for the LHC. The high granularity of the silicon strip detectors yields to low occupancies. New type of a silicon strip detector, single sided stereo angle detector (SSSD), has been designed to match the requirements of a LHC tracker. This detector allows a z-coordinate measurement without increasing the number of channels i.e. power consumption and it facilitates a tracker design with reasonable complicity.

A silicon microstrip counter with 25 μm strip pitch and two 128-channel low noise VLSI readout chips (“MICROPLEX”) has been tested in a 3.5 GeV negative pion beam at CERN. Results are given on the signal-to-noise ratio and on the cluster size spreading due to capacitive crosstalk.

The structure of silicon semi three-dimensional radiation detector is simulated on purpose to find out its electrical characteristics such as the depletion voltage and electric field. Two-dimensional simulation results are compared to voltage and electric field measurements done by a scanning electron microscope.

A cluster finding algorithm for a VLSI silicon strip detector readout chip has been developed and tested with real data. The algorithm includes a simpl

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

Abstract A large quantity of silicon microstrip detectors is foreseen to be used as part of the CMS tracker. A specific research and development program has been carried out with the aim of defining layouts and technological solutions suitable for the use of silicon detectors in high radiation environment. Results presented here summarise this work on many research areas such as techniques for device manufacturing, pre- and post-irradiation electrical characterization, silicon bulk defects analysis and simulations, system performance analytical calculations and simulations and test beam analysis. As a result of this work we have chosen to use single-sided, AC-coupled, poly silicon biased, 300 μm thick, p + on n substrate detectors. We feel confident that these devices will match the required performances for the CMS tracker provided they can be operated at bias voltages as high as 500 V. Such high-voltage devices have been succesfully manufactured and we are now concentrating our efforts in enhancing yield and reliability.

In pixelated silicon radiation detectors that are utilized for the detection of UV, visible, and in particular Near Infra-Red (NIR) light it is desirable to utilize a relatively thick fully depleted Back-Side Illuminated (BSI) detector design providing 100% Fill Factor (FF), low Cross-Talk (CT), and high Quantum Efficiency (QE).

The benefits of pixelated planar direct conversion semiconductor radiation detectors comprising a thick fully depleted substrate are that they offer low crosstalk, small output capacitance, and that the planar configuration simplifies manufacturing. In order to provide high quantum efficiency for high energy X-rays and Gamma-rays such a radiation detector should be as thick as possible. The maximum thickness and thus the maximum quantum efficiency has been limited by the substrate doping concentration: the lower the substrate doping the thicker the detector can be before reaching the semiconductor material's electric breakdown field. Thick direct conversion semiconductor detectors comprising vertical three-dimensional electrodes protruding through the substrate have been previously proposed by Sherwood Parker in order to promote rapid detection of radiation. An additional advantage of these detectors is that their thickness is not limited by the substrate doping, i.e., the size of the maximum electric field value in the detector does not depend on detector thickness. However, the thicker the substrate of such three dimensional detectors is the larger the output capacitance is and thus the larger the output noise is. In the novel direct conversion pixelated radiation detector utilizing a novel three dimensional semiconductor architecture, which is proposed in this work, the detector thickness is not limited by the substrate doping and the output capacitance is small and does not depend on the detector thickness. In addition, by incorporating an additional node to the novel three-dimensional semiconductor architecture it can be utilized as a high voltage transistor that can deliver current across high voltages. Furthermore, it is possible to connect a voltage difference of any size to the proposed novel three dimensional semiconductor architecture provided that it is thick enough—this is a novel feature that has not been previously possible for semiconductor components. Yet another feature of the novel three dimensional semiconductor architecture is that despite the thick substrate it can also be efficiently cooled.

For the LHC High Luminosity phase (HL-LHC) the CMS GEM Collaboration is planning to install new large size triple-GEM detectors in the forward region of the muon system (1.5<|η|<2.2) of the CMS detector.The muon reconstruction with triple-GEM chambers information included have been successfully integrated in the official CMS software, allowing physics studies to be carried out.The new sub-detector will be able to cope the extreme particle rates expected in this region along with a high spatial resolution.The resulting benefit in terms of triggering and tracking capabilities has been studied: the expected improvement in the performance of the muon identification and track reconstruction as well as the expected improvement coming from the lowering of the muon p T trigger tresholds will be presented.The contribution will review the status of the CMS upgrade project with the usage of GEM detector, discussing the trigger, the muon reconstruction performance and the impact on the physics analyses.

Abstract A telescope designed for the study of position sensitive detectors has been used for beam position monitoring. The telescope consists of eight silicon strip detectors and it is installed in the RD5 experiment at CERN. The telescope was tested with pion and muon beams in the energy range between 30 and 300 GeV/ c in the North Area of the SPS accelerator. The best impact point errors were 2.5 μm in the vertical and 2.9 μm in the horizontal direction. The signal-to-noise ratios of the detectors were around 40 and the efficiencies above 96%. The alignment of the telescope was very accurate and the correction for possible tilts did not essentially improve the performance.

Silicon strip detectors with double-sided readout have been designed and processed on 100-mm silicon wafers. Detectors with integrated coupling capacitors and polysilicon bias resistors were tested by static electrical measurements. A detector with VLSI readout electronics was measured in a test beam. Test beam measurements show signal over noise ratios of 39 on the detector p-side and 26 on the n-side.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

A test board suitable for mass testing of the production of CMS RPC link boards has been developed. The test board provides a fast first-level pass of the link boards at the production facility. This ensures that link boards with basic errors are not sent further to the long-term tests at the laboratory. A Field Programmable Gate Array (FPGA) circuit is used to scan connections and shorts of the board traces. The test board functioned well and provided a fast, less than 1 min per board, test at production.

VFAT3 is a front-end ASIC designed for the readout of GEM detectors in the CMS Muon system. The strategy for the chip design was to design the full chip at once but provide extensive test and debug facilities for individual characterization of each internal chip module. The verification platform consists of three parts; namely the software (running on a PC), the firmware (designed for a Kintex-7 FPGA development board) and a selection of VFAT3 dedicated hardware boards for the different stages of verification. The system was designed to accommodate all of the steps needed to fully test the chip. The first step is the functional testing for which only rather simple functions are needed. For the functional testing. the software has an interactive interface to communicate with the chip through the FPGA. The requirements for the hardware are mostly the possibility for the use of the main communication channels. For the characterization of the chip, the software offers a possibility to easily generate lists of routine instructions that can be uploaded to the FPGA and run as synchronous commands. This allows for example the scanning of the chip’s internal calibration DACs and creation of S-curves for all of the front-end channels. The hardware boards of the system allows access to the vast amount of test pads needed for the characterization and debug of the chip. The production tests require concatenated test routines where speed and execution efficiency are crucial. The software and the firmware of the system were designed to allow flexible evolution to increase the efficiency of complicated test routines.

An analog front-end in 130 (nm) CMOS technology was developed for the readout of triple-GEM detectors in the CMS experiment at CERN. The front-end has programmable peaking time - 15, 25, 35 and 45 (ns) - and gain - 48, 16.4 and 8.6 (mV/fC) - and is able to support a detector capacitance ranging from 0 to 120 (pF). In the design, many optimization techniques have been used to minimize the power consumption for given noise and timing requirements. Consequently, a single front-end channel consumes 790 (μA), and achieves an equivalent noise chargeof 620 (e-) at 0 (pF) detector capacitance with a noise slope of 33 (e-/pF). In order to simplify the peaking time programmability, an OTA-C based shaperwas used in the analog chain. The entire design hasbeen made radiation hard against TID. A chip comprising 129 front-end channels was fabricated and tested.

We have developed a novel radiation hard photon detector concept based on Modified Internal Gate Field Effect Transistor (MIGFET) wherein a buried Modified Internal Gate (MIG) is implanted underneath a channel of a FET. In between the MIG and the channel of the FET there is depleted semiconductor material forming a potential barrier between charges in the channel and similar type signal charges located in the MIG. The signal charges in the MIG have a measurable effect on the conductance of the channel. In this paper a radiation hard double MIGFET pixel is investigated comprising two MIGFETs. By transferring the signal charges between the two MIGs Non-Destructive Correlated Double Sampling Readout (NDCDSR) is enabled. The radiation hardness of the proposed double MIGFET structure stems from the fact that interface related issues can be considerably mitigated. The reason for this is, first of all, that interface generated dark noise can be completely avoided and secondly, that interface generated 1/f noise can be considerably reduced due to a deep buried channel readout configuration. Electrical parameters of the double MIGFET pixel have been evaluated by 3D TCAD simulation study. Simulation results show the absence of interface generated dark noise, significantly reduced interface generated 1/f noise, well performing NDCDSR operation, and blooming protection due to an inherent vertical anti-blooming structure. In addition, the backside illuminated thick fully depleted pixel design results in low crosstalk due to lack of diffusion and good quantum efficiency from visible to Near Infra-Red (NIR) light. These facts result in excellent Signal-to-Noise Ratio (SNR) and very low crosstalk enabling thus excellent image quality. The simulation demonstrates the charge to current conversion gain for source current read-out to be 1.4 nA/e.

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

Abstract A large use of silicon microstrip detectors is foreseen for the intermediate part of the CMS tracker. A specific research and development program has been carried out with the aim of finding design layouts and technological solutions for allowing silicon microstrip detectors to be reliably used on a high radiation level environment. As a result of this work single sided, AC-coupled, polysilicon biased, 300 μ m thick, p + on n substrate detectors were chosen. Irradiation tests have been performed on prototypes up to fluence 2×10 14  n/cm 2 . The detector performances do not significantly change if the detectors are biased well above the depletion voltage. S / N is reduced by less than 20%, still enough to insure a good efficiency and space resolution. Multiguard structures has been developed in order to reach high voltage operation (above 500 V).

The radiation hardness of diamond at the sensor level is studied by irradiating five sensors and studying them with various particle sources, without making any modifications to the sensors in between. The electronics used in the characterization is not irradiated to ensure that any observed effect is merely due to the sensor. Three sensors have received a fluence of 10 14 protons cm −2 and two 5⋅10 15 protons cm −2 . At the lower fluence, the impact on the charge collection efficiency is very small, when the applied bias voltage is above 1 V μm −1 . For the higher fluence, the charge collection efficiency is lower than expected based on earlier studies of diamond radiation hardness on the substrate level. Furthermore, it is noticed that the irradiation has a stronger impact on the signal amplitude recorded with a fast timing than with a charge sensitive amplifier.

The CMS experiment is planning to install Gaseous Electron Multiplier (GEM) chambers as part of the Muon upgrade for High Luminosity Operation at the LHC. The front-end ASIC (VFAT3) has been produced in volume together with its hybrid PCB. This paper describes the design of acusto m test bench for the production Quality Control (QC) of the VFAT3 hybrids. The full QC procedure incorporates calibration and performance measurements, database entries and statisti cal data analysis. The paper details the firmware and software functions to achieve the test time per hybrid to 2 minutes. The test system produced an overall 89% production yield including the wafer dicing and hybrid assembly losses.

A front-end readout chip VFAT3 was designed for the muon detector gas electron multipliers (GEM). GEMs were installed at the Compact Muon Solenoid (CMS) experiment of the Large Hadron Collider (LHC) at CERN for the high luminosity upgrade. The design of the VFAT3 uses 790 analog and 172 digital blocks which are highly integrated, thus it is crucial to ensure that the different blocks work together and the chip works as a whole. Mixed signal simulation methods were used to verify the high level functionality. Trigger latencies of 125, 150, 175 and 225 ns were found for front-end peaking times of 25, 50, 75 and 100 ns, respectively. The maximum trigger rate for reading out standard data packets was found to be 1.7 MHz. Results of the VFAT3 high level verification are presented and the simulation methods described.

We report selected results of laboratory measurements and beam tests of heavily irradiated microstrip silicon detectors. The detectors were single-sided devices, produced by different manufacturers and irradiated with different sources, for several total ionizing doses and fluences up to 4 /spl times/10/sup 14/ 1-MeV-equivalent neutrons per cm/sup 2/. Strip resistance and capacitance, detector leakage currents and breakdown performance were measured before and after irradiations. Signal-to-noise ratio and detector efficiency were studied in beam tests, for different values of the detector temperature and of the read-out pitch, as a function of the detector bias voltage. The goal of these test is to optimise the design of the final prototypes for the Silicon Strip Tracker of the CMS experiment at the CERN LHC collider.

Abstract The new silicon tracker layout (V4) is presented. The system aspects of the construction are discussed together with the expected tracking performance. Because of the high radiation environment in which the detectors will operate, particular care has been devoted to the study of the characteristics of heavily irradiated detectors. This includes studies on performance (charge collection, cluster size, resolution, efficiency) as a function of the bias voltage, integrated fluence, incidence angle and temperature.

The CMS silicon strip tracker involves about 70 m2 of instrumented silicon, with approximately 18500 microstrip detectors read out by 5 × 106 electronics channels. It has to satisfy a set of stringent requirements imposed by the environment and by the physics expected at the LHC: low cell occupancy and good resolution, radiation hardness aided by adequate cooling, low mass combined with high stability. These conditions have been incorporated in a highly modular design of the detector modules and their support structures, chosen to facilitate construction and to allow for easy assembly and maintenance.

The paper describes the Silicon Tracking System of the Compact Muon Solenoid (CMS) experiment that is foreseen to collect events from p–p collision at the Ecm=14 TeV at the CERN future Large Hadron Collider (LHC). The proposed system consists of four layers of silicon microstrip detectors placed between the two inner layers of the pixel detector and the outer microstrip gas chamber system. The barrel part covers the η region up to 1.8, instrumenting the central radial region between 20 and 50 cm. The forward–backward disks extend the coverage up to η=2.6. This paper will review the main characteristics and performances of the system, the actual status of the R&D activities that we are carrying on, and the status of the milestones we have to fulfill in view of the Technical Design Report expected at the end of the year.

The main characteristics of the DELPHI Microvertex Detector are presented. The performance in terms of impact parameter resolution, association efficiency, and ambiguity is evaluated after two years of data taking at LEP.

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