Search

The NA60 experiment has studied low-mass muon pair production in proton–nucleus collisions with a system of Be, Cu, In, W, Pb and U targets, using a 400 GeV proton beam at the CERN SPS. The transverse momentum spectra of the $$\rho /\omega $$ ρ/ω and $$\phi $$ ϕ mesons are measured in the full $$p_{\mathrm {T}}$$ pT range accessible, from $$p_{\mathrm {T}}= 0$$ pT=0 up to $$2 \, {\hbox {GeV/c}}$$ 2GeV/c . The nuclear dependence of the production cross sections of the $$\eta $$ η , $$\omega $$ ω and $$\phi $$ ϕ mesons has been found to be consistent with the power law $$\sigma _{\mathrm {pA}} \propto {\mathrm {A}}^\alpha $$ σpA∝Aα , with the $$\alpha $$ α parameter increasing as a function of $$p_{\mathrm {T}}$$ pT for all the particles, and an approximate hierarchy $$\alpha _\eta \approx \alpha _\phi > \alpha _\omega $$ αη≈αϕ>αω . The cross section ratios $$\sigma _\eta /\sigma _\omega $$ ση/σω , $$\sigma _\rho /\sigma _\omega $$ σρ/σω and $$\sigma _\phi /\sigma _\omega $$ σϕ/σω have been studied as a function of the size A of the production target, and an increase of the $$\eta $$ η and $$\phi $$ ϕ yields relative to the $$\omega $$ ω is observed from p–Be to p–U collisions.

In time of flight positron emission tomography (TOF-PET) and in particular for the EndoTOFPET-US Project (Frisch, 2013 [1] ), and other applications for high energy physics, the multi-digital silicon photomultiplier (MD-SiPM) was recently proposed (Mandai and Charbon, 2012 [2] ), in which the time of every single photoelectron is being recorded. If such a photodetector is coupled to a scintillator, the largest and most accurate timing information can be extracted from the cascade of the scintillation photons, and the most probable time of positron emission determined. The readout concept of the MD-SiPM is very different from that of the analog SiPM, where the individual photoelectrons are merely summed up and the output signal fed into the readout electronics. We have developed a comprehensive Monte Carlo (MC) simulation tool that describes the timing properties of the photodetector and electronics, the scintillation properties of the crystal and the light transfer within the crystal. In previous studies we have compared MC simulations with coincidence time resolution (CTR) measurements and found good agreement within less than 10% for crystals of different lengths (from 3 mm to 20 mm) coupled to SiPMs from Hamamatsu. In this work we will use the developed MC tool to directly compare the highest possible time resolution for both the analog and digital readout of SiPMs with different scintillator lengths. The presented studies reveal that the analog readout of SiPMs with microcell signal pile-up and leading edge discrimination can lead to nearly the same time resolution as compared to the maximum likelihood time estimation applied to MD-SiPMs. Consequently there is no real preference for either a digital or analog SiPM for the sake of achieving highest time resolution. However, the best CTR in the analog SiPM is observed for a rather small range of optimal threshold values, whereas the MD-SiPM provides stable CTR after roughly 20 registered photoelectron timestamps in the time estimator.

Highest time resolution in scintillator based detectors is becoming more and more important. In medical detector physics L(Y)SO scintillators are commonly used for time of flight positron emission tomography (TOF-PET). Coincidence time resolutions (CTRs) smaller than 100 ps FWHM are desirable in order to improve the image signal to noise ratio and thus give benefit to the patient by shorter scanning times. Also in high energy physics there is the demand to improve the timing capabilities of calorimeters down to 10 ps. To achieve these goals it is important to study the whole chain, i.e. the high energy particle interaction in the crystal, the scintillation process itself, the scintillation light transfer in the crystal, the photodetector and the electronics. Time resolution measurements for a PET like system are performed with the time-over-threshold method in a coincidence setup utilizing the ultra-fast amplifier-discriminator NINO. With 2×2×3 mm3 LSO:Ce codoped 0.4%Ca crystals coupled to commercially available SiPMs (Hamamatsu S10931-050P MPPC) we achieve a CTR of 108±5 ps FWHM at an energy of 511 keV. Under the same experimental conditions an increase in crystal length to 5 mm deteriorates the CTR to 123±7 ps FWHM, 10 mm to 143±7 ps FWHM and 20 mm to 176±7 ps FWHM. This degradation in CTR is caused by the light transfer efficiency (LTE) and light transfer time spread (LTTS) in the crystal. To quantitatively understand the measured values, we developed a Monte Carlo simulation tool in MATLAB incorporating the timing properties of the photodetector and electronics, the scintillation properties of the crystal and the light transfer within the crystal simulated by SLITRANI. In this work, we show that the predictions of the simulation are in good agreement with the experimental data. We conclude that for longer crystals the deterioration in CTR is mainly caused by the LTE, i.e. the ratio of photons reaching the photodetector to the total amount of photons generated by the scintillation whereas the LTTS influence is partly offset by the gamma absorption in the crystal.

The TDCpix is a novel pixel readout ASIC for the NA62 Gigatracker detector. NA62 is a new experiment being installed at the CERN Super Proton Synchrotron. Its Gigatracker detector shall provide on-beam tracking and time stamping of individual particles with a time resolution of 150 ps rms. It will consist of three tracking stations, each with one hybrid pixel sensor. The peak flow of particles crossing the detector modules reaches 1.27 MHz/mm 2 for a total rate of about 0.75 GHz. Ten TDCpix chips will be bump-bonded to every silicon pixel sensor. Each chip shall perform time stamping of 100 M particle hits per second with a detection efficiency above 99% and a timing accuracy better than 200 ps rms for an overall three-station-setup time resolution of better than 150 ps. The TDCpix chip has been designed in a 130 nm CMOS technology. It will feature 45×40 square pixels of 300 × 300 μ m 2 and a complex End of Column peripheral region including an array of TDCs based on DLLs, four high speed serializers, a low-jitter PLL, readout and control circuits. This contribution will describe the complete design of the final TDCpix ASIC. It will discuss design choices, the challenges faced and some of the lessons learned. Furthermore, experimental results from the testing of circuit prototypes will be presented. These demonstrate the achievement of key performance figures such as a time resolution of the processing chain of 75 ps rms with a laser sent to the center of the pixel and the capability of time stamping charged particles with an overall resolution below 200 ps rms.

The time resolution of photon detection systems is important for a wide range of applications in physics and chemistry. It impacts the quality of time-resolved spectroscopy of ultrafast processes and has a direct influence on the best achievable time resolution of time-of-flight detectors in high-energy and medical physics. For the characterization of photon detectors, it is important to measure their exact timing properties in dependence of the photon flux and the operational parameters of the photodetector and its accompanying electronics. We report on the timing of silicon photomultipliers (SiPM) as a function of their bias voltage, electronics threshold settings and the number of impinging photons. We used ultrashort laser pulses at 400 nm wavelength with pulse duration below 200 fs. We focus our studies on different types of SiPMs (Hamamatsu MPPC S10931-025P, S10931-050P and S10931-100P) with different SPAD sizes (25 mm, 50 mm and 100 mm) coupled to the ultrafast discriminator amplifier NINO. For the SiPMs, an optimum in the time resolution regarding bias and threshold settings can be reached. For the 50 mm type, we achieve a single photon time resolution of 80 ps sigma, and for saturating photon fluxes better than 10 ps sigma.

Over the last years, interest in using time-of-flightbased Positron Emission Tomography (TOF-PET) systems has significantly increased. High time resolution in such PET systems is a powerful tool to improve signal to noise ratio and therefore to allow smaller exposure rates for patients as well as faster image acquisition. Improvement in coincidence time resolution (CTR) in PET systems to the level of 200 ps FWHM requires the optimization of all parameters in the photon detection chain influencing the time resolution: crystal, photodetector and readout electronics. After reviewing the factors affecting the time resolution of scintillators, we will present in this paper the light yield and CTR obtained for different scintillator types (LSO:Ce, LYSO:Ce, LGSO:Ce, LSO:Ce:0.4Ca, LuAG:Ce, LuAG:Pr) with different cross-sections, lengths and reflectors. Whereas light yield measurements were made with a classical PMT, all CTR tests were performed with Hamamatsu-MPPCs S10931-050P. The CTR measurements were based on the time-over-threshold method in a coincidence setup using the ultra fast amplifier-discriminator chip NINO and a fast oscilloscope. Strong correlations between light yield and CTR were found. Excellent results have been obtained for LYSO crystals of 2 × 2 × 10 mm3 and LYSO pixels of 0.75 × 0.75 × 10 mm3 with a CTR of 175 ps and 188 ps FWHM, respectively. © 1963-2012 IEEE.

A study of the single photon time resolution (SPTR) and the coincidence time resolution (CTR) of the 4×4 MPPC array of Hamamatsu (S11827) has been performed to characterise the difference in signal response of an array compared to a single cell MPPC device. The monolithic 16-channel array has outputs from the 16 individual anodes and a common cathode. The common cathode has the disadvantage that a signal in any one of the 16 cells is coupled to the others. This is a source of cross-talk and also generates noise in the common ground affecting the timing performance of the array. The dependence of the SPTR on the applied bias voltage, the threshold and the laser intensity was first measured with a single 3×3 mm2 MPPC (10963-50P) since it is the basic element of the 4×4 MPPC array. The results show that when only a single cell of the array is connected (with all other cells ‘off’, i.e. with the anodes disconnected) the MPPC array response is much like the single-cell MPPC with an SPTR of 110 ps (sigma). We then tested the performance of the 4×4 array, incrementing the number of active cells in the array. Increasing the number of MPPC cells decreases the signal (measured by time-over-threshold) leading to a worsening of the SPTR proportional to the number of active MPPC cells. The merit of the differential readout for timing becomes evident when we compare the observed SPTR value of the MPPC-matrix with that of the single-ended readout. This improvement is also confirmed by the CTR measurement results. We measured the timing characteristics of the array using a 4×4 LYSO crystal matrix (3×3×15 mm3 per cell). The improvement in CTR (FWHM) from 283 ps to 226 ps is obtained by implementing the differential readout scheme. The results suggest that for critical timing applications, a differential output from each individual cell is an advantage.

The $K^+\rightarrow \pi^+ \nu \bar \nu$ decay is one of the theoretically cleanest meson decay where to look for indirect effects of new physics complementary to LHC searches. The NA62 experiment at CERN is designed to measure the branching ratio (BR) of this decay with 10\% precision. NA62 has been successfully launched in October 2014, took data in pilot runs in 2014 and 2015 reaching the final designed beam intensity. The NA62 experimental setup is illustrated and quality of data acquired in view of the final measurement is reported. The $K^+\rightarrow \pi^+ \nu \bar \nu$ decay is theoretically one of the cleanest meson decays and so a good place to look for indirect effects of new physics complementary to LHC searches. The NA62 experiment at CERN is designed to measure the branching ratio of this decay with 10\% precision. NA62 was commissioned in October 2014, took data in pilot runs in 2014 and 2015. The NA62 experimental setup is illustrated and data quality is reported. The K+→π+νν‾ decay is theoretically one of the cleanest meson decays and so a good place to look for indirect effects of new physics complementary to LHC searches. The NA62 experiment at CERN is designed to measure the branching ratio of this decay with 10% precision. NA62 was commissioned in October 2014, took data in pilot runs in 2014 and 2015. The NA62 experimental setup is illustrated and data quality is reported.

The design and technology of the silicon strip detector modules for the Semiconductor Tracker (SCT) of the ATLAS experiment have been finalised in the last several years. Integral to this process has been the measurement and verification of the tracking performance of the different module types in test beams at the CERN SPS and the KEK PS. Tests have been performed to explore the module performance under various operating conditions including detector bias voltage, magnetic field, incidence angle, and state of irradiation up to 3×1014 protons per square centimetre. A particular emphasis has been the understanding of the operational consequences of the binary readout scheme. © 2004 Elsevier B.V. All rights reserved.

The purpose of the RD2 project is to evaluate the feasibility of a silicon tracker and/or preshower detector for LHC. Irradiation studies with doses equivalent to those expected at LHC have been performed to determine the behavior of operational parameters such as leakage current, depletion voltage and charge collection during the life of the detector. The development of fast, dense, low power and low cost signal processing electronics is one of the major activities of the collaboration. We describe the first fully functional integrated analog memory chip with asynchronous read and write operations and level 1 trigger capture capabilities. A complete test beam system using this analog memory chip at 66 MHz has been successfully operated with RD2 prototype silicon detectors during various test runs. The flexibility of the electronics and readout have allowed us to easily interface our set-up to other data acquistion systems. Mechanical studies are in progress to design a silicon tracking detector with several million channels that may be operated at low (0–10°C) temperature, while maintaining the required geometrical precision. Prototype readout boards for such a detector are being developed and simulation studies are being performed to optimize the readout architecture.

The NA60 experiment studied low-mass muon pair production in proton–nucleus (p–A) collisions using a 400 GeV proton beam at the CERN SPS. The low-mass dimuon spectrum is well described by the superposition of the two-body and Dalitz decays of the light neutral mesons η, ρ, ω, η ′ and ϕ, and no evidence of in-medium effects is found. A new high-precision measurement of the electromagnetic transition form factors of the η and ω was performed, profiting from a 10 times larger data sample than the peripheral In–In sample previously collected by NA60. Using the pole-parameterisation | F ( M ) | 2 = ( 1 − M 2 / Λ 2 ) − 2 we find Λ η − 2 = 1.934 ± 0.067 (stat.) ±0.050 (syst.) ( GeV / c 2 ) − 2 and Λ ω − 2 = 2.223 ± 0.026 (stat.) ±0.037 (syst.) ( GeV / c 2 ) − 2 . An improved value of the branching ratio of the Dalitz decay ω → μ + μ − π 0 is also obtained, with B R ( ω → μ + μ − π 0 ) = [ 1.41 ± 0.09 (stat.) ± 0.15 (syst.) ] × 10 − 4 . Further results refer to the ρ line shape and a new limit on ρ / ω interference in hadron interactions.

Microchannel plates (MCP) based on hydrogenated amorphous silicon (a-Si:H) were recently introduced to overcome some of the limitations of crystalline silicon and glass MCP. The typical thickness of a-Si:H based MCPs (AMCP) ranges between 80 and 100 μm and the micromachining of the channels is realized by deep reactive ion etching (DRIE). Advantages and issues regarding the fabrication process are presented and discussed. Electron amplification is demonstrated and analyzed using Electron Beam Induced Current (EBIC) technique. The gain increases as a function of the bias voltage, limited to -340 V on account of high leakage currents across the structure. EBIC maps on 10° tilted samples confirm that the device active area extend to the entire channel opening. AMCP characterization with the electron beam shows gain saturation and signal quenching which depends on the effectiveness of the charge replenishment in the channel walls. © 2011 Elsevier B.V. All rights reserved.

We report on a systematic study of time resolution made with three different commercial silicon photomultipliers (SiPMs) (Hamamatsu MPPC S10931-025P, S10931-050P, and S10931-100P) and two LSO scintillating crystals. This study aimed to determine the optimum detector conditions for highest time resolution in a prospective time-of-flight positron emission tomography (TOF-PET) system. Measurements were based on the time over threshold method in a coincidence setup using the ultrafast amplifier-discriminator NINO and a fast oscilloscope. Our tests with the three SiPMs of the same area but of different SPAD sizes and fill factors led to best results with the Hamamatsu type of 50×50×μm2 single-pixel size. For this type of SiPM and under realistic geometrical PET scanner conditions, i.e., with 2×2×10×mm3 LSO crystals, a coincidence time resolution of 220 ±4 ps FWHM could be achieved. The results are interpreted in terms of SiPM photon detection efficiency (PDE), dark noise, and photon yield.

The authors describe techniques to make fast, sub-nanosecond time resolution solid-state detector systems using sensors with 3D electrodes, current amplifiers, constant-fraction comparators or fast wave-form recorders, and some of the next steps to reach still faster results.

A low-power multi-channel amplifier-discriminator was developed for application in highly time-resolved detection systems. The proposed circuit architecture, so-called Nino, is based on a time-over-threshold approach and shows a high potential for time-resolved readout of solid-state photo-detectors and of detectors based on vacuum technologies. The Irpics circuit was designed in a 250 nm CMOS technology, implementing 32 channels of a Nino version optimized to achieve high-time resolution on the output low-voltage differential signals (LVDS) while keeping a low power consumption of 10 mW per channel. Electrical characterizations of the circuit demonstrate a very low intrinsic time jitter on the output pulse leading edge, measured below 10 ps rms for each channel for high input signal charges ( > 100 fC) and below 25 ps rms for low input signal charges (20-100 fC). The read-out architecture moreover permits to retrieve the input signal charge from the timing measurements, while a calibration procedure was developed to correct for time walk variations of the output pulses. The Irpics circuit therefore shows a high potential of application in multi-channel detection systems requiring a high time resolution, as needed for Time Of Flight systems (TOF), Positron Emission Tomography (PET) or time-resolved spectroscopy.

In this paper we present the time-driven readout scheme for photodetectors in the domain of PET/CT applications. In our first test period as partner of the BioCare Consortium supported by the European Commission's FP6 framework program, we put emphasis on a scheme to be used with a LSO-APD detector suitable for both CT and PET, using exclusively electronics circuits developed for the LHC program at CERN. Compared to standard PMT-based systems, the proposed time-based readout method together with CERN ASICs produced comparable performance in terms of energy resolution, i.e. 15% FWHM, but had a markedly inferior timing response of 1.6 ns FWHM in a dual APD system. This is not attributed to the readout scheme itself but to crystal-inherent photon statistics and insufficient photodetector gain of the APDs. However, in our new follow-up test program employing the same electronics and readout scheme, silicon photomultipliers (SiPMs) replacing the previously used APDs showed excellent timing behavior of 420 and 235 ps FWHM for 1 and 3 photoelectrons, respectively. Timing resolution with 511 keV gammas on LSO reached 400 ps FWHM without time walk corrections.

Medical imaging has long benefited from advances in photon counting detectors arising from space and particle physics. We describe a microchannel plate-based detector system for high content (multi-parametric) analysis, specifically designed to provide a step change in performance and throughput for measurements in imaged live cells and tissue for the ‘omics’. The detector system integrates multi-channel, high time resolution, photon counting capability into a single miniaturized detector with integrated ASIC electronics, comprising a fast, low power amplifier discriminator and TDC for every channel of the discrete pixel electronic readout, and achieving a pixel density improvement of order two magnitudes compared with current comparable devices. The device combines high performance, easy reconfigurability, and economy within a compact footprint. We present simulations and preliminary measurements in the context of our ultimate goals of 20 ps time resolution with multi-channel parallel analysis (1024 channels).

In the framework of the European FP6's BioCare project, we develop a novel photo-detector readout technique to increase sensitivity and timing precision for molecular imaging in Positron Emission Tomography (PET) and Computer Tomography (CT). Within the Project's work packages, the CERN-BioCare group focuses on the development of a PET detection head suitable to process data from both PET and CT operation in one unit. The detector module consists of a LSO matrix coupled to an APD array. The signal is processed by a fast and low noise readout electronics recently developed for experiments at the Large Hadron Collider (LHC) at CERN. The functioning of the individual system components and the performance of the entire readout channel are presented.

New semiconductor detectors have recently gained a lot of attention for medical applications in general. Advances in CdZnTe-detector arrays might improve both energy resolution and spatial resolution of clinical X-ray systems. Alternative system designs based on TFA technology combining photo-detector arrays with CMOS electronics open a possibility for compact imaging cameras. This scenario allows for the use of alternative materials such as a-Si:H and HgI2 that can be applied alone or integrated with scintillators. Results obtained with such materials are presented.

The rare decay K + ! p + n n is an excellent process to probe Standard Model and indirectly search for new physics, complementary to the ongoing direct LHC searches. The NA62 experiment at CERN SPS aims to collect about 100 of such events in two years of data taking, keeping the background at the level of 10%. The physics motivation, experimental technique and status of the experiment are presented

The electron beam induced current (EBIC) technique was used to characterize a 32 lm thick hydrogenated amorphous silicon n–i–pdiode deposited on top of an ASIC, containing several channels of active feedback pre-amplifiers (AFP) with peaking time of 5 ns. Thehomogeneity of the sample together with the edge effects induced by the unevenness of the ASIC substrate were studied with low doses of10–30 keV electron beam. The degradation of a-Si:H pixel detectors was measured with intense electron beam. Their charge collectionand transient time were characterized with a 660 nm pulsed laser before and after the thermal annealing. All the diodes show approx-imately a full recovery of charge collection after thermal annealing. 2006 Elsevier B.V. All rights reserved. PACS: 73.61.Jc; 61.43.Dq; 29.40.Wk; 61.82.FkKeywords: Amorphous semiconductors; Detectors; Radiation; SEM; EBIC; ASIC 1. IntroductionElectron beam induced current (EBIC) is a powerfulsemiconductor analysis technique [1,2], which employs a10–30 keV electron beam from a scanning electron micro-scope (SEM) to scan the detector active area, and inducinga signal on the pixels’ electrodes. This signal can be directlyreadout or can be feedback to the SEM system in such away that any change in the generation, drift or recombina-tion of the generated carriers in the detector is displayed asvariations of contrast in EBIC images. EBIC imaging isvery sensitive to electron–hole recombination, so the EBICanalysis is very useful in finding defects such as voids,crystallographic imperfections, dislocations and grainboundaries.The EBIC method has a high potential for the character-ization of n–i–p hydrogenated amorphous silicon (a-Si:H)diodes on application specified integrated circuit (ASIC)[3], as it can also be used to study the electric field in thedepletion region and the degradation of a-Si:H with highdoses of electrons [4]. The EBIC signal depends primarilyon the strength of the electric field, so for a given potentialacross a junction, high dopant conditions result in narrowdepletion region and higher electric field, which can be usedto study the doping homogeneity. It must be noted that inaddition to electric field strength, the relative dimension ofdepletion region compared to generation volume is also animportant factor in EBIC collection efficiency. This is thereason why it is valuable to understand the basic devicestructure in order to interpret the results correctly.In this work, we tried to study the homogeneity of theactive area and the effects of the unevenness of the ASICsubstrate, which may induce regions with high electric field.This can also explain the high leakage currents that we

3D detectors, with electrodes penetrating through the silicon substrate were fabricated, and characteristics such as speed, radiation hardness and edge sensitivity were studied. The signal shape was observed using a fast, low-noise transimpedance amplifier. The rise time of the signal obtained for a minimum ionizing particle was faster than 3 ns at room temperature. This is in agreement with earlier calculations of 3D sensors that showed the charge collection time to be between 1 and 2 ns. Similar tests were performed on detectors after exposure to proton beams with doses ( 1.8 × 10 15 24 GeV protons / cm 2 ) equivalent to those expected after 10 years at the innermost layers of the ATLAS experiment at the large hadron collider (LHC). Edge sensitivity was measured at the advanced light source at Lawrence Berkeley Laboratory, using an X-ray micro-beam. The detectors were measured to be efficient up to less than 10 μ m from their physical edges. Results presented in this paper confirm the suitability of this design for possible future LHC upgrades, where the integrated fluence is expected to increase by a factor of 10. Moreover, their speed characteristics have placed them as potential candidates for the CERN linear collider (CLIC) where the bunch-crossing separation can be as short as 1.2 ns.

Preliminary radiation tests of hydrogenated amorphous silicon n-i-p photodiodes deposited on a coated glass substrate are presented in this paper. These tests have been performed using a 24 GeV proton beam. We report results on the fluence dependence of the diode dark current and of the signal induced by a proton spill. © 2005 Published by Elsevier B.V.

For the full exploitation of the excellent timing properties of the Multigap Resistive Plate Chamber (MRPC), front-end electronics with special characteristics are needed. These are (a) differential input, to profit from the differential signal from the MRPC (b) a fast amplifier with less than 1 ns peaking time and (c) input charge measurement by Time-Over-Threshold for slewing correction. An 8-channel amplifier and discriminator chip has been developed to match these requirements. This is the NINO ASIC, fabricated with 0.25 μ m CMOS technology. The power requirement at 40 mW/channel is low. Results on the performance of the MRPCs using the NINO ASIC are presented. Typical time resolution σ of the MRPC system is in the 50 ps range, with an efficiency of 99.9 % .

TOTEM will measure the total pp cross-section at LHC by using a luminosity independent method based on simultaneous evaluation of the total elastic and inelastic rates. For an extended coverage of the inelastic and diffractive events, two forward tracking telescope are employed. The elastically or diffractively scattered protons are measured by a set of special detectors, which can be moved close to the circulating protons beams. The paper describes the physics reach of the experiment and the detectors which are being considered.

We present the simulated and measured performance of a transimpedance amplifier designed in a quarter micron CMOS process. Containing only NMOS and PMOS devices, this amplifier can be integrated in any submicron CMOS process. The main feature of this design is the use of a transistor in the feedback path instead of a resistor. The circuit has been optimized for reading signals coming from silicon strip detectors with few pF input capacitance. For an input charge of 4 fC, an input capacitance of 4 pF and a transresistance of 135 kΩ, we have measured an output pulse fall time of 3 ns and an Equivalent Noise Charge (ENC) of around 350 electrons rms. In view of the operation of the chip at cryogenic temperatures, measurements at 130 K have also been carried out, showing an overall improvement in the performance of the chip. Fall times down to 1.5 ns have been measured. An integrated circuit containing 32 channels has been designed and wire bonded to a silicon strip detector and successfully used for the construction of a high-intensity proton beam hodoscope for the NA60 experiment. The chip has been laid out using special techniques to improve its radiation tolerance, and it has been irradiated up to 10 Mrd (SiO 2 ) without any degradation in the performance.

The LHC (Large Hadron Collider) is currently under construction at CERN, the European Laboratory for Particle Physics based in Geneva. The experiments at this accelerator will use substantial numbers of silicon detectors. These are close to the interaction point and will be exposed to very high fluences ( up to 10 15 particles cm −2 ) during their operating life. Such detectors are crucial to the disentanglement of important decay events and it is vital to guarantee a homogeneous reliable performance during their operation. Parameters like the charge collection efficiency (CCE) and response time will be discussed. Limitations of present technologies will be analysed and future strategies explored. Results obtained using alternative detector designs, such as 3D geometry, material engineering by oxygen diffusion and unconventional operational conditions are surveyed.

CERN and Rio Current-mode Amplifier is an amplifier–shaper–discriminator chip, developed in 0.25 μm CMOS radiation tolerant technology for the readout of the LHCb muon wire chambers. This paper presents the design and test of three prototype chips, including positive and negative pre-amplifier, differential shaper, differential discriminator and LVDS driver circuits.

The rare decays K+ →π+νν¯ are excellent tool to make tests of new physics complementary to LHC thanks to their theoretically cleanness. The NA62 experiment at CERN SPS aims to collect of the order of 100 K+ →π+νν¯ events in two years of data taking, keeping the background at the level of 10%. Part of the experimental apparatus has been commissioned during the technical run in 2012. The physics prospects and status of the experiment will be reviewed.

The ALICE1LHCB chip is a mixed-mode integrated circuit designed to read out silicon pixel detectors for two different applications: particle tracking in the ALICE Silicon Pixel Detector and particle identification in the LHCb Ring Imaging Cherenkov detector. To satisfy the different needs for these two experiments, the chip can be operated in two different modes. In tracking mode all the 50 μm×425 μm pixel cells in the 256×32 array are read out individually, whilst in particle identification mode they are combined in groups of 8 to form a 32×32 array of 400 μm×425 μm cells. Radiation tolerance was enhanced through special circuit layout. Sensitivity to coupling of digital signals into the analog front end was minimized. System issues such as testability and uniformity further constrained the design. The circuit is currently being manufactured in a commercial 0.25 μm CMOS technology.

The design and results of a radiation hard switched gain charge amplifier optimised for a large dynamic range and large input capacitance are described. The peaking time is 25 ns, dynamic ranges are 0.1–50 minimum ionising particles (MIPs) (high gain) and 1–400 MIPs (low gain), signal to noise (S/N)>10 for Cin

A new front-end for a pixel detector readout chip was designed. A non-standard topology was used to achieve low noise and fast return to zero of the preamplifier to be immune to pile-up of subsequent input signals. This front-end has been implemented on a pixel detector readout chip developed in a commercial 0.25 μm CMOS technology for the ALICE and LHCb experiments. This technology proved to be radiation tolerant when special layout techniques are used, and provides sufficient density for these applications. The chip is a matrix of 32 columns each containing 256 readout cells. Each readout cell comprises this front-end and digital readout circuitry, and has a static power consumption of about 60 μW.

After having reviewed the main noise sources in an MOS transistor the paper presents results about the noise performance of a 0.25 μm CMOS technology which is being extensively used to design radiation tolerant ASICs for the LHC experiments (the Large Hadron Collider at present under construction at CERN). The 1/f and white noise are studied for n- and p-channel devices with five different gate lengths, in weak, moderate and strong inversion and for different drain to source and bulk to source biases. The noise degradation is measured after irradiation with 10 keV X-rays and after annealing. The results are commented in view of the use of these transistors in low-noise front-end circuits.

High energy particle physics experiments investigate the nature of matter through the identification of subatomic particles produced in collisions of protons, electrons, or heavy ions which have been accelerated to very high energies. Future experiments will have hundreds of millions of detector channels to observe the interaction region where collisions take place at a 40 MHz rate. This paper gives an overview of the electronics requirements for such experiments and explains how data reduction, timing distribution, and radiation tolerance in commercial CMOS circuits are achieved for these big systems. As a detailed example, the electronics for the innermost layers of the future tracking detector, the pixel vertex detector, is discussed with special attention to system aspects. A small-scale prototype (130 channels) implemented in standard 0.25 /spl mu/m CMOS remains fully functional after a 30 Mrad(SiO/sub 2/) irradiation. A full-scale pixel readout chip containing 8000 readout channels in a 14 by 16 mm/sup 2/ area has been designed.

We present the development of a high-speed, single-photon counting, Hybrid Photo Detector (HPD). The HPD consists of a vacuum tube, containing the detector assembly, sealed with a transparent optical input window. Photons incident on the photocathode eject a photoelectron into a large electric field, which accelerates the incident electron onto a silicon detector. The silicon detector is bump bonded to a Medipix readout chip. This set-up allows for the detection and readout of low incident photon intensities at rates that are otherwise unattainable with current camera technology. Reported is the fabrication of the camera that brings together a range of sophisticated design and fabrication techniques and the expected theoretical imaging performance. Applications to cellular and molecular microscopy are also described in which single-photon-counting abilities at high frame rates are crucial.

High-throughput photon counting with high time resolution is a niche application area where vacuum tubes can still outperform solid-state devices. Applications in the life sciences utilizing time-resolved spectroscopies, particularly in the growing field of proteomics, will benefit greatly from performance enhancements in event timing and detector throughput. The HiContent project is a collaboration between the University of Leicester Space Research Centre, the Microelectronics Group at CERN, Photek Ltd., and end-users at the Gray Cancer Institute and the University of Manchester. The goal is to develop a detector system specifically designed for optical proteomics, capable of high content (multi-parametric) analysis at high throughput. The HiContent detector system is being developed to exploit this niche market. It combines multi-channel, high time resolution photon counting in a single miniaturized detector system with integrated electronics. The combination of enabling technologies; small pore microchannel plate devices with very high time resolution, and high-speed multi-channel ASIC electronics developed for the LHC at CERN, provides the necessary building blocks for a high-throughput detector system with up to 1024 parallel counting channels and 20 ps time resolution. We describe the detector and electronic design, discuss the current status of the HiContent project and present the results from a 64-channel prototype system. In the absence of an operational detector, we present measurements of the electronics performance using a pulse generator to simulate detector events. Event timing results from the NINO high-speed front-end ASIC captured using a fast digital oscilloscope are compared with data taken with the proposed electronic configuration which uses the multi-channel HPTDC timing ASIC.

A radiation tolerant pixel detector readout chip has been developed in a commercial 0.25 /spl mu/m CMOS process. The chip is a matrix of two columns of 65 identical cells. Each readout cell comprises a preamplifier, a shaper filter, a discriminator, a delay line and readout logic. The chip occupies 10 mm/sup 2/, and contains about 50000 transistors. Electronic noise (/spl sim/220 e rms) and threshold dispersion (/spl sim/160 e rms) allow operation at 1500 e average threshold. The radiation tolerance of this mixed mode analog-digital circuit has been enhanced by designing NMOS transistors in enclosed geometry and introducing guardrings wherever necessary. The chip, which was developed at CERN for the ALICE and LHCb experiments, was still operational after receiving 3.6/spl times/10/sup 13/ protons over an area of 2/spl times/2 mm. Other chips were irradiated with X-rays and remained fully functional up to 30 Mrad (SiO/sub 2/) with only minor changes in analog parameters. These results indicate that careful use of deep submicron CMOS technologies can lead to circuits with high radiation tolerance.

Detection of scintillation light from LSO (Lutetiumoxyorthosilicate) crystals used in positron emission tomography (PET) is traditionally based on photo- multipliers. The proposal is to develop a novel photo- sensor, which is based on vertically integrating an hydrogenated amorphous silicon (a-Si:H) film on a pixel readout chip. The a-Si:H film is deposited with a n-i-p diode structure. The ASIC (Application Specific Integrated Circuit) performs both signal amplification and readout processing. The advantage of such an approach is the extremely compact and low-cost design, together with ultra- low noise signal retrieval. In addition the a-Si:H offers the technological advantage of direct deposition on the wafer thanks to the low deposition temperature. The article presents the results of quantum efficiency measured on different types of a-Si:H photodiodes deposited on glass (DC measurement) and CMOS circuit (AC measurement). Quantum Efficiency (QE) up to 80% has been measured at the wavelength of interest for the optimized photodiodes. © 2007 Elsevier B.V. All rights reserved.

This work concerns the development of a methodology specially devoted to lateral parasitic transistors that limit the total dose hardness of CMOS technologies. This methodology is based on i) the irradiation of standard NMOS transistors followed by ii) isochronal annealing measurements to determine energetic spectra of the field oxide trapped charge. Post irradiation effects have been evaluated through additional isothermal annealing experiments at 75/spl deg/C which are consistent with isochronal results. We propose a test procedure which allows to determine physical parameters helpful to improve comparison and qualification of CMOS commercial technologies.

An additional noise component is observed in the noise spectrum of transistors in a partially-depleted (PD) medium-thickness SOI-CMOS technology. We identify the origin of this additional noise in the noisy resistance of the body film. This resistance, coupled to the gate capacitance, forms an RC filter and generates the hump-shape of the additional noise component. Several experimental observations that support this model are presented.

Two prototype chips for the analogue readout of silicon strip detectors in the ATLAS Semiconductor Tracker (SCT) have been designed and manufactured, in 32 channels and 128 channel versions, using the radiation hard BiCMOS DMILL process. The SCTA chip comprises three basic blocks: front-end amplifier, analogue pipeline and output multiplexer. The front-end circuit is a fast transresistance amplifier followed by an integrator, providing fast shaping with a peaking time of 25 ns, and an output buffer. The front end output values are sampled at 40 MHz rate and stored in a 112-cell deep analogue pipeline. The delay between the write pointer and trigger pointer is tunable between 2 /spl mu/S and 2.5 /spl mu/s. The chip has been tested successfully and subsequently irradiated up to 10 MraB. Full functionality of all blocks of the chip has been achieved at a clock frequency of 40 MHz both before and after irradiation. Noise figures of ENC=720 e/sup ./+33 e/sup .//pF before irradiation and 840 e/sup ./+33 e/sup .//pF after irradiation have been obtained.

The TDCpix is a novel readout ASIC for hybrid pixel detectors with emphasis on timing. It is designed to meet the requirements of the Gigatracker, the kaon spectrometer of the NA62 experiment at the CERN Super Proton Synchrotron. The Gigatracker consists of three tracking and time-tagging hybrid pixel modules. A time resolution better than 200 ps is required. The silicon pixel sensors will be 60×27 mm2 and 200 µm thick. A pixel size of 300×300 µm2 will provide the required position and momentum resolution. Each sensor will be read out by 2×5 TDCpix ASICs, connected by flip-chip bonding. The main capabilities of the TDCpix chip will be to detect and time stamp more than 130 million charged particle hits per second (>0.8 MHz/mm2) with a timing resolution below 200 ps (RMS). This contribution describes the completed and final design of the TDCpix ASIC. The chip has been designed in a 130 nm CMOS process. It combines a matrix of 45×40 pixel channels with amplifying and discriminating circuits and a complex peripheral region including an array of TDCs based on DLLs, four high speed (3.2 Gb/s) data serializers, a low-jitter PLL, bandgap references, DACs, readout and control circuits. Mandatory correction of the time-walk of the discriminator leading edge is based on the measurement of Time over Threshold. The laboratory characterization of a prototype chip demonstrated a resolution better than 75 ps RMS for injected charges larger than 2 fC and constant pulse shapes. The achievement of the target timing resolution with real particles has been demonstrated in beam tests using prototype chips and prototype hybrid modules.

The Gigatracker (GTK) is a hybrid silicon pixel detector designed for the NA62 experiment at CERN. The beam spectrometer, made of three GTK stations, has to sustain high and non-uniform particle rate (∼1 GHz in total) and measure momentum and angles of each beam track with a combined time resolution of 150 ps. In order to reduce multiple scattering and hadronic interactions of beam particles, the material budget of a single GTK station has been fixed to 0.5% X 0 . The expected fluence for 100 days of running is 2 × 10 14 1 MeV n eq /cm 2 , comparable to the one foreseen in the inner trackers of LHC detectors during 10 years of operation. To comply with these requirements, an efficient and very low-mass ( 0 ) cooling system is being constructed, using a novel microchannel cooling silicon plate. Two complementary read-out architectures have been produced as small-scale prototypes: one is based on a Time-over-Threshold circuit followed by a TDC shared by a group of pixels, while the other makes use of a constant-fraction discriminator followed by an on-pixel TDC. The read-out ASICs are produced in 130 nm IBM CMOS technology and will be thinned down to 100 μm or less. An overview of the Gigatracker detector system will be presented. Experimental results from laboratory and beam tests of prototype bump-bonded assemblies will be described as well. These results show a time resolution of about 170 ps for single hits from minimum ionizing particles, using 200 μm thick silicon sensors. © 2012 Elsevier B.V. All rights reserved.

Scintillation crystals have a wide range of applications in detectors for high energy and medical physics. They are recquired to have not only good energy resolution, but also excellent time resolution. In medical applications, L(Y)SO crystals are commonly used for time of flight positron emission tomography (TOF-PET). This study aims at determining the experimental and theoretical limits of timing using L(Y)SO based scintillators coupled to silicon photomultipliers (SiPMs). Measurements are based on the time-over-threshold method in a coincidence setup utilizing the ultra-fast amplifier-discriminator NINO and a fast oscilloscope. Using a 2 × 2 × 3 mm3 LSO:Ce codoped 0.4% Ca crystal coupled to a commercially available SiPM (Hamamatsu S10931-050P MPPC), we achieve a coincidence time resolution (CTR) of 108±5ps FWHM measured at E=511keV. We determine the influence of the data acquisition system to 27±2ps FWHM and thus negligible as compared to the CTR. This shows that L(Y)SO scintillators coupled to SiPM photodetectors are capable of achieving very good time resolution close to the desired 100ps FWHM for TOF-PET systems. To fully understand the measured values, we developed a simulation tool in MATLAB that incorporates the timing properties of the photodetector, the scintillation properties of the crystal and the light transfer within the crystal simulated by SLITRANI. The simulations are compared with measured data in order to determine their predictive power. Finally we use this model to discuss the influence of several important parameters on the time resolution like scintillation rise- and fall time and light yield, as well as single photon time resolution (SPTR) and the detection efficiency of the SiPM. In addition we find the influence of photon travel time spread in the crystal not negligible on the CTR, even for the used 2 × 2 × 3 mm 3 geometry. © CERN 2013.

The Omega3/LHC1 pixel detector readout chip comprises a matrix of 128 × 16 readout cells of 50 μm × 500 μm and peripheral functions with 4 distinct modes of initialization and operation, together more than 800 000 transistors. Each cell contains a complete chain of amplifier, discriminator with adjustable threshold and fast-OR output, a globally adjustable delay with local fine-tuning, coincidence logic and memory. Every cell can be individually addressed for electrical test and masking. First results have been obtained from electrical tests of a chip without detector as well as from source measurements. The electronic noise without detector is ∼ 100 e− rms. The lowest threshold setting is close to 2000 e− and non-uniformity has been measured to be better than 450 e− rms at 5000 e− threshold. A timewalk of

New projective prototypes of a scintillator/lead sandwich type sampling calorimeter Shashlik with a silicon preshower detector have been constructed and tested with an electron beam at CERN-SPS. The energy resolution is measured to be 8.7%/sqrt(E(GeV)) in stochastic term. 0.330/E(GeV) in noise term and 0.5% in constant term. The angular resolution is better than 70 mrad/sqrt(E(GeV)).