Search

Cosmic ray muon has strong penetrating power and no ionizing radiation hazards, which makes it an ideal probe for detecting special nuclear materials (SNMs). In this article, a high spatial resolution muon tomography system based on Micromegas detectors is proposed to optimize the imaging time and quality. The proposed system includes eight Micromegas detectors based on the thermal bonding technique and a scalable readout system. In addition, a multiplexing method based on position encoding is developed to reduce the number of electronics channels by order of magnitude. The spatial resolution of the proposed system with encoding readout can reach a value of hundred micrometers. Finally, a tomography test is performed, and test results show that this proposed system can image 2-cm objects and distinguish different materials. [ABSTRACT FROM AUTHOR]

Optical imaging of muon beams is a promising method for range estimations. However, our previous optical imaging method could only measure 2-D projection images. To measure the beam ranges and widths at any position of the muon beam, 3-D beam images are desired. For this purpose, we developed an optical imaging system using a silver-activated zinc sulfide (ZnS(Ag)) sheet combined with a mirror and a cooled charge-coupled device (CCD) camera. The ZnS(Ag) sheet was set in a black box and irradiated by a positive muon beam at the Japan Proton Accelerator Research Complex (J-PARC). Acrylic plates were used to absorb the muon beam. The measured optical images with different thicknesses of the acrylic plates were stacked and interpolated to create a 3-D optical image, and then the depth and lateral profiles were evaluated. From the depth profile derived from the 3-D image, the Bragg peak position could be estimated. The lateral profiles at the Bragg peak positions could also be derived. We confirmed that 3-D optical imaging was possible using the developed system with a ZnS(Ag) sheet. The system is promising for measuring muon beam distribution, conducting research on muons, and developing future muon radiotherapy. [ABSTRACT FROM AUTHOR]

We present a field-programmable gate array (FPGA)-based technique for the on-line identification of highly ionizing particles in a liquid xenon (LXe) detector. The method was developed and successfully exploited to select $\alpha $ particles emitted by 241Am sources submerged in LXe in an overwhelming, mostly beam-related, $\gamma $ -ray background. After revising the main features of xenon and other liquid noble gases as ultra-violet (UV) scintillating media, we describe the algorithm idea and its firmware implementation. We then present the results in terms of efficiency and background suppression for the real-time $\alpha $ -particle tagging and the limits of the MEG trigger configuration. Finally, we show that in MEG II we are going to overcome the main issues and further improve the performances. [ABSTRACT FROM AUTHOR]

We study, by optical spectroscopy, the properties of high-current electric arcs that form between opening Cu contacts. The presence of a current that increases linearly with a rate of about 14 kA/ms leads to the separation of the contacts and to the formation of a bridge of molten metal that eventually ruptures. We show that after the molten bridge rupture, it takes about 40 $\mu \text{s}$ for the initial arc to be at local thermal equilibrium. This long thermalization time suggests that the plasma density during that time range is low, which we confirm using a simple modeling of the energy transfer between electrons and heavy particles. We explain these low densities by the fact that the molten bridge rupture leads to the formation of a shock wave. The initial dense plasma rapidly expands and a region with a pressure below the background pressure forms between the two contacts, leading to low plasma densities and long thermalization times. [ABSTRACT FROM AUTHOR]

The Mu2e experiment at the Fermilab Muon Campus will search for the coherent neutrinoless conversion of a muon into an electron in the field of an aluminum nucleus with a sensitivity improvement by a factor of 10 000 over existing limits. Such a charged lepton flavor-violating reaction probes new physics at a scale unavailable with direct searches at either present or planned high-energy colliders. The Mu2e Trigger and Data Acquisition (TDAQ) system exploits otsdaq as its online Data Acquisition System (DAQ) solution. Developed at Fermilab, otsdaq integrates both the artdaq DAQ and the art analysis frameworks for event transfer, filtering, and processing. otsdaq is an online DAQ software suite with a focus on flexibility and scalability and provides a multi-user, web-based, interface accessible through a web browser. The read out controllers (ROCs) stream out zero-suppressed data continuously from the detector subsystems to the data transfer controllers (DTCs). The data stream is then read over the peripheral component interconnect express (PCIe) bus to a software filter algorithm that selects events which are combined with the data flux coming from a cosmic-ray veto (CRV) system. The detector control system (DCS) has been developed using the experimental physics and industrial control system (EPICS) open source platform for monitoring, controlling, alarming, and archiving. The DCS has been integrated into otsdaq. A prototype of the TDAQ system and the DCS has been built at Fermilab’s Feynman Computing Center. In this article, we report on the progress of the integration of this prototype in the online otsdaq software. [ABSTRACT FROM AUTHOR]

J-PARC E16 is an experiment to examine the origin of hadron mass through a systematic measurement of spectral changes of vector mesons in nuclei. The measurement of $e^{+}e^{-}$ pairs from the decay of vector mesons will provide the information of the partial restoration of the chiral symmetry in a normal nuclear density. To resolve a pulse pile-up and achieve good discrimination of $e^{+}$ and $e^{-}$ from the background of a reaction rate of an order of 10 MHz, the data acquisition (DAQ) system uses waveform sampling chips of APV25 and DRS4. The trigger rate and data rate are expected to be 1 kHz and 120–330 MiB/s, respectively. The DAQ system for readout of APV25 and DRS4 were developed, where events were synchronized by common trigger and tag data. The first commissioning in beam, called Run-0a, was performed in June 2020 with about 1/4 of the designed setup. The DAQ worked with a trigger rate of 300 Hz in the Run-0a and the main bottleneck was a large data size of APV25. Further optimization of the DAQ system will improve the performance. [ABSTRACT FROM AUTHOR]

The CMS experiment at the LHC selects events with a two-level trigger system, the Level-1 (L1) trigger, and the high-level trigger (HLT). The HLT reduces the rate from 100 to about 1 kHz and has access to the full detector readout and runs a streamlined version of the offline event reconstruction. During LHC Run-2, the peak instantaneous luminosity reached values up to $2.0\times 10^{34}$ cm−2s−1, posing a challenge to the online event selection. An overview of the HLT system at CMS, the online physics object reconstruction, and the main triggers using those physics objects in 2016–2018 proton collision data-taking period is presented. The performance of a representative set of physics triggers is also discussed. [ABSTRACT FROM AUTHOR]

The reconstruction and identification of tau leptons decaying to hadrons are crucial for new physics signatures and precision measurements with tau leptons in the final state at the LHC. The recently deployed tau identification algorithm using deep neural network (DNN) at the CMS experiment for the discrimination of hadronic tau decays from quark or gluon induced jets, electrons, or muons is an ideal example for the exploitation of modern deep learning neural network techniques in high energy physics. With this algorithm, significant suppression of tau misidentification rates has been achieved for the same identification efficiency compared to previous algorithms at the LHC, leading to considerable performance gains for physics studies with tau leptons. This new multiclass DNN-based tau identification algorithm at CMS and its performance are presented in this article. [ABSTRACT FROM AUTHOR]

The COherent Muon to Electron Transition (COMET) experiment aims to search for the neutrinoless muon to electron transition process with new sensitivity levels. The online trigger system is an integral part of achieving the sensitivity levels required and will be subject to an expected neutron fluence of up to $10^{12}\,\,n \cdot \mathrm {cm}^{-2}$ within regions inside the detector solenoid. Consequently, a significant number of soft errors in the logic of the onboard field programmable gate arrays (FPGAs) can occur, requiring error correction for single event upsets and firmware reprogramming schemes for unrecoverable soft errors. We studied the radiation tolerance of the COMET Phase-I front-end trigger system, called COMET TRIgger (COTTRI), subject to neutron fluence on order $10^{12}\,\,n \cdot \mathrm {cm}^{-2}$ with multiple error correcting codes and automatic firmware reconfiguration. The regions measured were the configuration random access memory (RAM), block RAM (BRAM) and also in a multigigabit transfer link using copper cables that will be used for communication between different trigger boards during Phase-I. The resulting cross sections observed suggest the most significant impact to the experiment will come from unrecoverable soft errors in configuration RAM (CRAM), with dead time expected to be 4.2% ± 1.3%. The effect of multibit errors in BRAM was found to be almost negligible in COMET Phase-I. In addition, multiple solutions have already been proposed in order to suppress these errors further. Soft errors observed in the multigigabit transfer links were measured to be of two orders of magnitude less impact compared to the unrecoverable errors in CRAM. We concluded that the COTTRI system meets the trigger requirement in COMET Phase-I. [ABSTRACT FROM AUTHOR]

Ground-level cosmic ray muon detections have various potential applications in the predictions of space and Earth weather variations and muon tomography. However, in order to push its practical applications, a low-power, low-cost, high-accuracy, and portable ground-level cosmic ray muon detection system needs to be developed. In this article, we present a high time-resolution and low-power readout integrated circuit (ROIC) for portable ground-level cosmic ray muon detection. The ROIC comprises preamplifiers, comparators, encoding modules, a delay-locked loop (DLL), and a data transfer module. The preamplifiers amplify the weak signals produced by the muon detector. The comparators convert the amplified signals into digital signals. The encoding modules extract and store the time information of the input pulses produced by the comparator, and the data transfer module transmits them to a microcontroller unit (MCU). A pulse edge detecting method using DLL clocks is employed to improve the time-resolution and limit the power consumption of the ROIC. A 32-channel prototype of the ROIC was designed and fabricated in a 0.18- $\mu \text{m}$ mixed-signal CMOS process. The main chip size is 11.4 mm2. A one-channel double-layer plastic scintillator muon detector was used to test the performance of the ROIC. A time-resolution of 1.0 ns was achieved with a system clock of 50 MHz, and the ROIC power consumption was measured at 1.9 mW/channel. Compared with existing muon readout electronics systems, the system using the proposed ROIC achieves high time-resolution and accuracy, with low power consumption and a smaller size, making it suitable for portable real-time cosmic ray muon detection. [ABSTRACT FROM AUTHOR]

The Belle II experiment at the SuperKEKB collider at KEK, Tsukuba, Japan has successfully started taking data with the full detector in March 2019. Belle II is a luminosity frontier experiment of the new generation to search for physics beyond the Standard Model of elementary particles, from precision measurements of a huge number of $B$ and charm mesons and tau leptons. To read out the events at a high rate from the seven subdetectors of Belle II, we adopt a highly unified readout system, including a unified trigger-timing distribution system (TTD), a unified high-speed data link system (Belle2link), and a common backend system to receive Belle2link data. Each subdetector frontend readout system has a field-programmable gate array (FPGA) in which unified firmware components of the TTD receiver and Belle2link transmitter are embedded. The system is designed for data taking at a trigger rate up to 30 kHz with a dead-time fraction of about 1% in the frontend readout system. The trigger rate is still much lower than our design. However, the background level is already high because of the initial vacuum condition and other accelerator parameters, and it is the most limiting factor of the accelerator and detector operation. Hence, the occupancy and radiation effects to the frontend electronics are rather severe, and they cause various kinds of instabilities. We present the performance of the system, including the achieved trigger rate, dead-time fraction, and stability, and discuss the experience gained during the operation. [ABSTRACT FROM AUTHOR]

A new Muon-to-Central-Trigger Processor Interface (MUCTPI) was built as part of the upgrade of the ATLAS Level-1 trigger system for the next Run of the Large Hadron Collider at CERN. The MUCTPI has 208 high-speed optical serial links for receiving muon candidates from the muon trigger detectors. Three high-end field-programmable gate arrays (FPGAs) are used for real-time processing of the muon candidates, for sending trigger information to other parts of the trigger system, and for sending summary information to the data acquisition and monitoring system. A System-on-Chip (SoC) is used for the control, configuration, and monitoring of the hardware and the operation of the MUCTPI. The SoC consists of an FPGA part and a processor system (PS). The FPGA part provides communication with the processing FPGAs, while the PS runs software for communication with the run-control system of the ATLAS experiment. In this article, we will describe our experience with running CentOS Linux on the SoC. Cross-compilation together with the existing framework for building the ATLAS trigger and data acquisition (TDAQ) software is being used in order to allow the deployment of the TDAQ software directly on the SoC. [ABSTRACT FROM AUTHOR]

A field programmable gate array (FPGA)-based online trigger system has been developed for the COherent Muon To Electron Transition (COMET) Phase-I experiment, which searches for muon-to-electron conversion as a signature of New Physics beyond the Standard Model. A drift chamber and trigger counters are devised to detect a mono-energetic electron from the conversion process in a 1-T solenoidal magnetic field. A highly intense muon source enables reaching unprecedented experimental sensitivity, however, it also generates undesirable background particles which increase the trigger rate to a much higher level than the capability of the data acquisition (DAQ) system. By using hit information from the drift chamber in addition to the trigger counter, the newly proposed online trigger system efficiently suppresses the background trigger rate while keeping the signal-event acceptance large. A characteristic of this system is the utilization of machine learning (ML) techniques for optimizing lookup tables (LUTs) implemented in hardware. Simulation studies show that the signal-event acceptance of the online trigger is 96% while the background trigger rate is reduced from 91 to 13 kHz. The global trigger system and trigger electronics that construct a distributed trigger architecture were built. The total trigger latency was estimated to be $3.2~\mathrm {\mu s}$. The trigger system test was carried out by using a part of the drift-chamber readout region. [ABSTRACT FROM AUTHOR]

The Mu3e experiment aims to find or exclude the lepton flavor violating decay μ+ → e+e−e+$ with a sensitivity of one in 1016 muon decays. The first phase of the experiment is currently under construction at the Paul Scherrer Institute (PSI, Switzerland), where beams with up to 108 muons per second are available. The detector will consist of an ultra-thin pixel tracker made from High-Voltage Monolithic Active Pixel Sensors (HV-MAPS), complemented by scintillating tiles and fibers for precise timing measurements. The experiment produces about 100Gbit/s of zero-suppressed data, which are transported to a filter farm using a network of field programmable gate arrays (FPGAs) and fast optical links. On the filter farm, tracks and three-particle vertices are reconstructed using highly parallel algorithms running on graphics processing units, leading to a reduction of the data to 100 Mbyte/s for mass storage and offline analysis. This article introduces the system design and hardware implementation of the Mu3e data acquisition and filter farm. [ABSTRACT FROM AUTHOR]

The large Hadron collider (LHC) is expected to increase its center-of-mass energy from 13 to 14 TeV for Run 3 scheduled from 2022 to 2024. After Run 3, upgrades for the high-luminosity-LHC (HL-LHC) program are planned and the operation will start in 2027, increasing the instantaneous luminosity to 5.0–7.5 times its nominal luminosity. Continuous upgrades of the ATLAS trigger system are planned to cope with the high event rate and to keep the physics acceptance. During the long shutdown period before Run 3, new detectors will be installed to improve the trigger performance. A new trigger logic, combining information from detectors located outside of the magnetic field and new detectors installed inside the magnetic field, will be introduced for Run 3 to reduce the trigger rate. In order to handle data from the various detectors, a new trigger processor board has been developed and the design is presented. During the upgrade for HL-LHC, the trigger and readout systems of the first level hardware-based part are planned to be upgraded. Full-granularity information will be transferred to the trigger processor board which enables more OFF-line like track reconstruction in the hardware-based system. To handle the full-granularity information and perform the hardware-based track reconstruction, the trigger processor board will be equipped with a field programmable gate array (FPGA) with hundreds of transceivers and a large memory. Expected performance for the hardware-based endcap muon trigger in Run 3 and HL-LHC will also be presented. [ABSTRACT FROM AUTHOR]

Pions make up a large part of the hadronic environment typical of accelerator mixed fields. Characterizing device cross sections against pions is usually disregarded in favor of tests with protons, whose single-event latch-up (SEL) cross section is, nonetheless, experimentally found to be lower than that of pions for all energies below 250 MeV. While Monte Carlo simulations are capable of reproducing such behavior, the reason for the observed pion cross-section enhancement can only be explained by a deeper analysis of the underlying mechanisms dominating proton–silicon and pion–silicon reactions. The mechanisms dominating the SEL response are found to vary with the energy under consideration. While a higher pion nuclear reaction rate, that is, probability of interaction, can explain the observed latch-up cross-section enhancement at energies >100 MeV, it is the volume-equivalent linear energy transfer (LETEQ) of the secondary ions that keeps the pion latch-up response high at lower energies. The higher LETEQ of secondary ions from pion–silicon interactions is caused by the pion absorption mechanism, which is highly exothermic. In spite of the observed higher cross section for pions, the high-energy hadron approximation is found to still provide reliable estimations of the latch-up response of a device in mixed fields. [ABSTRACT FROM AUTHOR]

Negative and positive muon-induced single-event upsets (SEUs) are studied in 20-nm bulk planar SRAMs. Muon irradiation is performed using a mono-energetic source with varying the muon energy. The energy dependence of the cross sections (CSs) of SEUs and multiple-cell upsets (MCUs) shows the significant contribution of muon capture reactions for the negative muon, as reported in previous studies. Interestingly, MCU events are found for the positive muon, in contrast to the previous studies. The CSs for the negative and positive muons are compared with that for the other terrestrial radiations: high-energy neutrons, thermal neutrons, and alpha particles. The voltage dependence of the SEU CS, together with the empirical model for charge collection, demonstrates the difference in the contributing secondary ions among the negative muon, the high-energy neutron, and the thermal neutron. The MCU events are thoroughly analyzed in terms of their ratio to the total events and their fail bit patterns. The results reveal that the MCU characteristics for the negative muon are different from that for the other terrestrial radiations due to the muon capture reactions, where parasitic bipolar effects and the isotropic emission of secondary ions are important factors. [ABSTRACT FROM AUTHOR]

Arrays of superconducting transition-edge sensor (TES) microcalorimeters are attractive for some X-ray experiments where the combination of higher collection efficiency than crystal spectrometers and much better energy resolution than semiconductor detectors is enabling. For hard X-ray (>2 keV) applications, a TES is often integrated with an extra absorber to extend its dynamic range, quantum efficiency and collecting area. For >100 keV applications, millimeter size absorbers have been manually attached to TES pixels after fabrication. At lower energies, the absorber size needs to be much smaller, because a large heat capacity degrades energy resolution. In that case, the absorber is directly electroplated or evaporated on the TES during the fabrication process. In this work, we present TES microcalorimeters optimized for the intermediate hard X-ray energy region (20 keV ∼ 100 keV) that have thick absorbers directly deposited during the TES fabrication process. This microcalorimeter is designed to measure high-resolution muonic atom transition X-ray spectra as a method to study quantum electrodynamics (QED) effects. The absorber is comprised of evaporated gold and electroplated bismuth layers and is designed to optimize dynamic range, collecting efficiency, and energy resolution in the 20 keV to 45 keV energy range. A prototype with pure gold absorbers has been fabricated and characterized, in order to obtain a first experimental reference in the detector development process. [ABSTRACT FROM AUTHOR]

Neutrons with energies between 0.1 and 10 MeV can significantly impact the soft error rate (SER) in SRAMs manufactured in scaled technologies, with respect to high-energy neutrons. Their contribution is evaluated in accelerator, ground-level, and avionic (12 km of altitude) environments. Experimental cross sections were measured with monoenergetic neutrons from 144 keV to 17 MeV, and the results benchmarked with Monte Carlo simulations. It was found that even 144 keV neutrons can induce upsets due to elastic scattering. Moreover, neutrons in the 0.1–10 MeV energy range can induce more than 60% of the overall upset rate in accelerator applications, while their contribution can exceed 18% in avionics. The SER due to neutrons below 3 MeV, whose contribution has always been considered negligible, is found to be up to 44% of the total upsets in accelerator environments. These results have strong radiation hardness assurance (RHA) implications for those environments with high fluxes of neutrons in the 0.1–10 MeV energy range. [ABSTRACT FROM AUTHOR]

A new silicon-strip readout chip named “SliT” has been developed for the measurement of the muon anomalous magnetic moment and electric dipole moment (EDM) of the muon at Japan Proton Accelerator Research Complex (J-PARC). The SliT chip is designed in the Silterra 180-nm CMOS technology with mixed-signal integrated circuits. An analog circuit incorporates a conventional charge-sensitive amplifier, shaping amplifiers, and two distinct discriminators for each of the 128 identical channels. A digital part includes storage memories, an event building block, a serializer, and low voltage differential signaling (LVDS) drivers. A distinct feature of the SliT is utilization of the zero-crossing architecture, which consists of a CR– RC filter followed by a CR circuit as a voltage differentiator. This architecture allows generating hit signals with subnanosecond amplitude-independent time walk, which is the primary requirement for the experiment. The test results show a time walk of 0.38 ± 0.16 ns between 0.5 and 3 MIP signals. The equivalent noise charge is 1547 ± 75 e− (rms) at Cdet =33 pF as a strip-sensor capacitance. SliT128C satisfies all requirements of the J-PARC muon g−2/EDM experiment. [ABSTRACT FROM AUTHOR]

The trigger selection capabilities of the ATLAS detector have been significantly enhanced for the Large Hadron Collider (LHC) Run-2 in order to cope with the higher event rates and with a large number of simultaneous interactions (pile-up) per proton–proton bunch crossing. A new hardware system, designed to analyze real-time event-topologies at level-1, came to full use in 2017. A hardware-based track reconstruction system, expected to be used real time in run-3, is designed to provide track information to the high-level software trigger at its full input rate. The high-level trigger (HLT) selections largely rely on off-line-like reconstruction techniques and in some cases multivariate analysis methods. Despite the sudden change in LHC operations during the second half of 2017, which caused an increase in pile-up and, therefore, also in CPU usage of the trigger algorithms, the set of triggers (so-called trigger menu) running online has undergone only minor modifications thanks to the robustness and redundancy of the trigger system and the use of a leveling luminosity scheme in agreement with LHC and other experiments. This article gives a brief yet comprehensive review of the real-time performance of the ATLAS trigger system in 2017. Considerations will be presented on the most relevant parameters of the trigger (efficiency to collect signal and output data rate) and details on some aspects of the algorithms which are run real time on the HLT CPU farm will be presented. [ABSTRACT FROM AUTHOR]

The pion resonance in the nuclear reaction cross section is seen to have a direct impact on the single-event effect (SEE) cross section of modern electronic devices. This was experimentally observed for single-event upsets and single-event latchup. Rectangular parallelepiped (RPP) models built to fit proton data confirm the existence of the pion SEE cross-section resonance. The impact on current radiation hardness assurance (RHA) soft error rate (SER) predictions is, however, minimal for the accelerator environment since this is dominated by high neutron fluxes. The resonance is not seen to have a major impact on the high-energy hadron equivalence approximation established for testing in mixed-field facilities. [ABSTRACT FROM AUTHOR]

Muon-induced single event upset (SEU) is predicted to increase with technology scaling. Although previous works investigated the dependencies of muon-induced SEU cross sections on energy, voltage, and technology, the angle of incidence of terrestrial muons is not always perpendicular to the chip surface. Consequently, the impact of the angle of incidence of muons on SEUs should be evaluated. This study conducts negative muon irradiation tests on bulk and fully depleted silicon on insulator static random access memories at two angles of incidence: 0° (vertical) and 45° (tilted). The tilted incidence drifts the muon energy peak to a higher energy as expected. However, the SEU characteristics in the bulk device between the vertical and tilted incidences, including the voltage dependences of the SEU cross sections and multiple cells upset patterns, are similar despite the unexpected impact on the SEU cross section at an operating voltage of 0.4 V. [ABSTRACT FROM AUTHOR]

Optoelectronic components are the most sensitive devices of systems exposed to radiation environments. Displacement damage (DD) effects can severely degrade the performances of such devices, which are extensively used in critical electronic systems installed in particle accelerators or nuclear power plants. This work investigates the use of application-specific radiation spectra for damage estimations in operation instead of mono-energetic proton or neutron irradiations. An analysis of the characteristics of the Large Hadron Collider (LHC) radiation environment in terms of DD is presented in this work along with the demonstration of the ability of the CERN High Energy Accelerator Mixed Field (CHARM) facility of CERN to reproduce them. Then, a set of optocouplers made of gallium arsenide (GaAs), indium gallium arsenide (InGaAs), and aluminum gallium arsenide (AlGaAs) are tested under these environments, and the results are compared to proton and neutron irradiations. [ABSTRACT FROM AUTHOR]

Negative and positive muon irradiation tests of static random access memories (SRAMs) were performed at Muon Science Innovation Channel (MuSIC) of Research Center for Nuclear Physics (RCNP), Osaka University. The muon-induced single event upset (SEU) cross sections for 65-nm bulk SRAMs were measured. The SRAM device was irradiated by the muon beams with average momenta ranging from 37.8 to 41.0 MeV/c at the beam exit. The incident muon fluence was measured using a one-by-one muon detection system with a plastic scintillator by taking advantage of the direct current (dc) muon beam and reliable absolute values of SEU cross sections were obtained. In addition to the measurement of the SEU cross sections, we measured muonic X-rays from the irradiated device to investigate the relation between the measured SEU cross section and the emission rate of muonic X-rays associated with the stopping position of the muons as a function of incident muon momentum. The result suggested that negative muons have a significant effect on SEUs by the emission of secondary light ions via negative muon capture reaction when negative muons stop near sensitive volumes (SVs) in SRAMs. [ABSTRACT FROM AUTHOR]

The Large Hadron Collider beauty (LHCb) experiment is one of the four main particle detectors located at the Large Hadron Collider. After the high-luminosity upgrade of the accelerator, the expected radiation dose faced by the LHCb electromagnetic calorimeter will reach peak values of 1 MGy in the centermost part, an amount not tolerable by the currently employed Shashlik technology, which demands a novel radiation hard design. In addition, a time resolution of few tens of picoseconds and a cell lateral size of about 2 cm are planned for track reconstruction purposes by the collaboration. In this article, the crystal spaghetti design was evaluated, a sampling geometry where scintillating crystal fibers are embedded in the dense absorbing material. The prototype was tested at CERN super proton synchrotron (SPS) with muons and electrons measuring an energy resolution of 3% for electrons at 20 GeV, tilting the prototype by 3° both horizontally and vertically with respect to the incident beam, and a time resolution of 79 ps. The results presented in this article show the feasibility of the design. [ABSTRACT FROM AUTHOR]

We investigate, through measurements and simulations, the possible direct ionization impact on the accelerator soft-error rate (SER), not considered in standard qualification approaches. Results show that, for a broad variety of state-of-the-art commercial components considered in the 65–16-nm technological range, indirect ionization is still expected to dominate the overall SER in the accelerator mixed-field. However, the derived critical charges of the most sensitive parts, corresponding to ~0.7 fC, are expected to be at the limit of rapid direct ionization dominance and soft-error increase. [ABSTRACT FROM AUTHOR]

This article describes a series of experimental measurements and calculations designed to quantify the scattering and albedo effects on neutron spectra and their consequences on single-event effect (SEE) sensitivities. An experimental approach was proposed to investigate the scattering and albedo neutron spectra using a 252Cf facility and for several scene topologies. A highly sensitive neutron spectrometer based on a Bonner sphere system (BSS) is used, allowing to measure neutron energy from thermal to tens of megaelectron-volts. To complete previous SEE measurements on 45 nm, the soft error rate (SER) was recorded on 28-nm technology. A second part considers complex topologies including concrete walls and high-density polyethylene (HDPE) blocks to represent a design facility and the shielding to protect some parts of the SEE test board, respectively. The results showed that devices are more impacted by the presence of materials, especially HDPE. Indeed, almost 25% of the events are due to the secondary neutrons. Orders of magnitude are not critical, nevertheless, they warn about taking into account the albedo contributions and how to add materials in the vicinity of measurement devices. [ABSTRACT FROM AUTHOR]

The planned upgrade of the A Large Ion Collider Experiment (ALICE) inner tracking system (ITS) aims at improving the ALICE performance in terms of spatial resolution and data rate readout. The new ITS will be a low-material-budget, high-granularity detector. It comprises seven concentric layers of monolithic active pixel sensors (MAPS), called ALPIDE, which are based on the TowerJazz 180-nm CMOS technology. In this article, we report on detection performance and radiation hardness studies of ALPIDE sensors. We show that these sensors keep having high detection efficiency for minimum ionizing particles (MIPs) (>99%) and low fake-hit rate while being radiation hard to some ${ 1.7} \times { 10}^{ 13}\,\,1$ MeV $\text{n}_{\text {eq}}$ cm−2 of nonionizing energy loss (NIEL) and 2.7 Mrad of total ionization dose (TID), which exceeds the expected radiation load during the detector lifetime ten times. ALPIDE sensors thus completely fulfill the design requirements. In addition, we show that measured cluster shape frequencies obtained at different operating points (thresholds, bias voltages) are well described with the state-of-the-art ALICE Monte Carlo simulation. [ABSTRACT FROM AUTHOR]

An experiment to measure an invariant mass of $\phi $ mesons in nuclear medium is planned as the J-PARC E16 experiment. A trigger merging module (TRG-MRG) has been developed to detect leading-edges from 256 channels of discriminator-output signals and transmit those serialized hit data to trigger decision module with four optical links. The result of the test shows enough performance of the TRG-MRG as 1-ns time-to-digital converter (TDC) and data multiplexer with four 6.25 Gb/s transceivers. [ABSTRACT FROM AUTHOR]

This paper presents a major improvement in the NTHU Flight Dose Calculator, which not only extends its capabilities but also introduces three new features: the automatic batch analysis of multiple flights, route dose summation over all scheduled flights, and estimation of the cumulative spectra of cosmic rays along a flight path. Based on the results of extensive FLUKA simulations of atmospheric showers generated by galactic cosmic rays, a global database containing energy spectra and effective dose rates of neutrons, protons, muons, pions, electrons, positrons, photons, and heavy ions at various altitudes ranging from sea level up to 70 km was constructed and parameterized accounting for the dependences of altitude, geomagnetic cutoff rigidity, and solar modulation. The dose calculator was revised to accommodate and utilize the newly expanded database, which enables the estimation of aviation route doses and cumulative spectra of various radiation components by performing a series of interpolations and integration along a path. A program is a user-friendly tool for assessing radiation exposure of air travel due to galactic cosmic rays. The new features of the batch processing and route dose summation greatly facilitate studies of flight route effects and individual dose monitoring of aircrew. The cumulative spectra of various components can provide additional information for in-depth dosimetry analyses, designing experiments for measuring related quantities, and estimating single-event effects in avionics. [ABSTRACT FROM AUTHOR]

Multiple-cell upset (MCU) in static random access memory (SRAM) is a major concern in radiation effects on very large scale integration (VLSI) since it can spoil error correcting codes (ECCs). Neutron-induced MCUs have been characterized for terrestrial environment. On the other hand, negative muon-induced MCUs, which are caused by secondary ions generated through muon capture process, were recently reported. Neutron- and negative muon-induced MCUs are both caused by secondary ions, and hence, they are expected to have some similarity. In this paper, we compare negative muon- and neutron-induced MCUs in 65-nm bulk SRAMs at the irradiation experiments using spallation and quasi-monoenergetic neutrons and monoenergetic negative muons. The measurement results show that the dependencies of MCU event cross section on operating voltage are almost identical. The high operating voltage makes both negative muon- and neutron-induced MCU cross sections larger due to parasitic bipolar action. Consequently, large-bit MCUs are observed under the irradiation using both neutrons and muons. On the other hand, at 0.4 V, neutrons induce larger-bit MCUs (> 12 bits) whereas negative muons cause up to 11-bit MCUs. Upsets of 3 or larger bits along word line (WL) are observed at spallation neutron beams. To explain the similarity of MCUs induced by neutrons and negative muons, the Monte Carlo simulation is conducted to investigate the deposited charge. The distributions of deposited charge obtained by the simulation are consistent with the above-mentioned experimental observations. [ABSTRACT FROM AUTHOR]

Negative and positive muon-induced single-event upset (SEU) rates were estimated for 65-nm bulk and ultrathin body and thin buried oxide silicon-on-insulator (UTBB-SOI) static random access memories (SRAMs). The SEU cross sections for muon incidence on the two SRAMs were experimentally characterized and compared. The experimental results showed that the negative muon SEU cross sections for the bulk SRAM are significantly larger than those for the UTBB-SOI. Estimation of muon SEU rates at ground level was performed using the experimental results and the Monte Carlo simulation with the Particle and Heavy Ion Transport code System (PHITS). The estimated muon SEU rates were compared with the measured neutron SEU rates. The contribution of muons was found to be considerably smaller than that of neutrons. Attenuation effect of muons and neutrons in a five-story building was also investigated by particle transport simulation with PHITS. The muon SEU rate on the first floor was estimated to be at most 10% of the neutron SEU rate on the same floor. [ABSTRACT FROM AUTHOR]

The Level-1 barrel trigger of the ATLAS experiment is based on the resistive plate chambers (RPCs) detectors. The on-detector trigger electronics identifies muons with specific values of transverse momentum, by using coincidences between different layers of detectors. Trigger data are then transferred from on-detector to off-detector trigger electronics boards. Data are processed by a complex system, which combines trigger data from the barrel and the end-cap regions and provide the combined muon candidate to the central trigger processor (CTP). The system has been performing well for almost a decade. However, in order to cope with continuously increasing large hadron collider luminosity and more demanding requirements on trigger efficiency and performance, various upgrades for the full-trigger system were already deployed and others are foreseen in the next years. Most of the trigger upgrades are based on the state-of-the-art technologies and allow designing more complex trigger menus, increasing processing power and data transfer bandwidth in order to send more trigger candidates, to perform topological selections, and to support new physics studies. In this paper, we describe the design of the first prototype of the barrel interface board, designed around a Xilinx field-programmable gate array, which transfers RPC trigger data to the CTP system; the board supports the optical transmission of trigger data with fixed latency and new trigger algorithms. We discuss the design strategies, the hardware implementation, and the results of the first functional and integration tests. [ABSTRACT FROM AUTHOR]

The design and performance of a new front-end acquisition system is presented in this paper. It was developed to be used with muon array with resistive plate chamber (RPCs) for tagging air showers (MARTA’s) RPC detectors that measure the muonic component of cosmic ray air showers. The system is hybrid and capable of counting active channels and performing a charge measurement. It is low power (1.43 W per 64 channels), compact ($21.6 \times 14.4\,\,\mathrm {cm^{2}}$ per 64 channels), stable, and reliable to comply with the strict demands of field operation associated with experiments that measure air showers. The front-end is based on an application-specified integrated circuit [Multi Anode Read-Out Chip (MAROC)] with 64 input channels, which is responsible for the digitization of the RPC signals. While a simple threshold measurement is applied after a fast shaper to count particles, the charge measurement is performed by an analog to digital converter that reads the peak of a slow shaper. An field-programmable gate array is responsible for control of all the digital part which includes storing the MAROC outputs and sending them to a Central Unit [via low voltage differential signal (LVDS)] or PC (via USB). Both the count and charge measurement performance are assessed. The threshold efficiency curve is measured for different temperatures. For all the conditions tested, the efficiency is 100% for charges higher than 52 fC. The overall efficiency to detect muons is studied by placing an RPC between a hodoscope and comparing the efficiency of the front-end with another established data acquisition system. The efficiency results are consistent within the statistical uncertainties of the measurements showing that the MARTA front-end does not introduce unwanted inefficiencies in the setup. The charge measurement is tested in the laboratory using a signal generator. Different shaping conditions and input charges are used to study the waveform of the slow shaper. A linear dependence between input charge and the value measured by the MAROC was found and taken as the calibration curve for the particular channel tested. [ABSTRACT FROM AUTHOR]

The increase in atmospheric CO2 concentrations has initiated research into carbon sequestration methods. One possibility is to store CO2 in subsurface porous reservoirs. Monitoring the injected CO2 plume is vital because escaping CO2 poses health and environmental risks. Typically, seismic reflection methods are used to determine the change in density due to the replacement of brine by CO2 in the reservoir but this is expensive and not continuous. A potential alternative is to use cosmic muon tomography to measure density changes in the reservoir as a function of time. This paper describes the development of a muon detector that will be capable of being deployed in boreholes. The detector will be designed to have the required dimensions, an angular resolution of approximately 2°, and be mechanically robust. The prototype design is based on alternating layers of scintillating rods, which can provide 4-D reconstruction of the overburden to detect small changes in density at depths up to approximately 2 km. Geant4, a Monte Carlo simulation code, is being used to develop models to guide the design of the physical configuration. Preliminary testing and measurements have been performed to validate the simulation predictions and optimize physical performance parameters. The simulated and preliminary experimental results are presented here. [ABSTRACT FROM AUTHOR]

A portable muography detector was developed for measuring infrastructure degradation and its performance was tested. The detector consists of two muon position sensitive detectors (mu-PSDs) of the area of 140 mm $\times \,\, 140$ mm, placed in a compact light-shielding box. Each mu-PSD consists of plastic scintillating fibers connected to multipixel photon counters (MPPCs). To suppress the gain deviation of the MPPCs, the box was heat insulated and its inner air temperature was maintained by Peltier cooling–heating modules. The mu-PSD pixel size was 8.75 mm $\times \,\, 8.75$ mm and the distance between the two mu-PSDs was set to 100 mm in order to achieve a solid angle resolution of 8 msr when measuring typical pieces of infrastructure at thicknesses of several tens of centimeters. The intensity of cosmic-ray muons was measured as a function of zenith angle on the ground and was found to be in good agreement with the well-known empirical formula for muon intensity at Earth’s surface. The structural interior of a seven-story concrete building was then successfully imaged with the muography detector placed in the building’s basement. [ABSTRACT FROM AUTHOR]

We have performed an irradiation test of low-energy positive and negative muons on 65-nm ultra-thin body and thin buried oxide silicon-on-insulator static random access memories. The single event upset (SEU) cross sections were measured systematically as a function of incident muon momentum and operating supply voltage. The experimental results show that the negative muon SEUs occur at about three times higher rate than the positive muon ones at the supply voltage of 0.5 V when the incident muons stop near the sensitive volume (SV). A Monte-Carlo simulation with the particle and heavy ion transport code system (PHITS) was carried out using a simple SV model. The simulation based on the PHITS using the SV model is found to reproduce generally well the momentum dependence of the measured SEU cross sections for both positive and negative muons. From the simulation, the charged particles and secondary ions having significant influence on SEUs are specified and the differences between negative and positive muons are discussed. [ABSTRACT FROM AUTHOR]

Irradiation experiments of positive and negative muon were conducted for 65-nm bulk CMOS static random-access memory. The experimental results reveal that parasitic bipolar action (PBA) contributes to negative muon-induced upsets. We observe an increase in single event upset (SEU) cross section at higher operation voltage under negative muon irradiation while positive muon shows an opposite decreasing tendency. Also, the proportion of multiple-cell upset (MCU) events to all the negative muon-induced upset events is up to 66, and more than a 20-bit MCU is observed. Furthermore, Monte Carlo simulation of particle and heavy ion transport code system (PHITS) is performed for explaining the difference in SEU between positive and negative muons. We also discuss the charge threshold that triggers PBA-induced MCU using measurement and simulation results with different momentum muons. The estimated threshold is much larger than the charge that the positive muons can deposit, which well explains that no PBA-induced MCUs are observed under positive muon irradiation. [ABSTRACT FROM AUTHOR]

The Mu2e experiment at Fermilab searches for the charged-lepton flavor violating (CLFV) conversion of a negative muon into an electron in the field of an aluminum nucleus, with a distinctive signature of a monoenergetic electron of energy slightly below the muon rest mass (104.967 MeV). The Mu2e goal is to improve by four orders of magnitude the search sensitivity with respect to the previous experiments. Any observation of a CLFV signal will be a clear indication of new physics. The Mu2e detector is composed of a tracker, an electromagnetic calorimeter, and an external veto for cosmic rays surrounding the solenoid. The calorimeter plays an important role in providing particle identification capabilities, a fast online trigger filter, a seed for track reconstruction while working in vacuum, in the presence of 1-T axial magnetic field and in a harsh radiation environment. The calorimeter requirements are to provide a large acceptance for 100-MeV electrons and reach at these energies: 1) a time resolution better than 0.5 ns; 2) an energy resolution <10%; and 3) a position resolution of 1 cm. The calorimeter design consists of two disks, each one made of 674-undoped cesium iodine crystals read by two large area arrays of UV-extended silicon photomultipliers (SiPMs). We report here the construction and the test of the Module-0 prototype. The Module-0 has been exposed to an electron beam in the energy range around 100 MeV at the Beam Test Facility in Frascati. Preliminary results of timing and energy resolution at normal incidence are shown. A discussion of the technical aspects of the calorimeter engineering is also reported in this paper. [ABSTRACT FROM AUTHOR]

A model for heavy baryon/meson–nucleon cross sections is proposed and implemented in the framework of the GEANT4 toolkit. The comparisons with experimental data are presented. [ABSTRACT FROM AUTHOR]

The Muon g-2 experiment at Fermilab will measure the muon anomalous magnetic moment $a=(g-2)/2$ to an unprecedented precision of 0.14 parts per million (ppm). To this aim, a calibration system made by a laser source and light distribution will provide short light pulses directly into each crystal of the 24 calorimeters to measure energy and arrival time of the decay positrons. Each calorimeter is composed of a 6\times 9$ matrix of PbF_{2} crystals where each crystal is read by a silicon photomultiplier. Continuous monitoring and state-of-the-art calibration are required in order to control the detector response. The calibration light pulses are monitored, both at the laser output (source monitor) and at the end of the distribution system (local monitor), before delivery to the calorimeters. For example, the light pulses are read by specific photodetectors, whose signals are digitized by electronics designed to match the experimental requirements. All readout electronics boards are hosted in a crate where the controller manages the complete data collection, operates as an event builder and transfers data to the online farm system through a gigabit Ethernet connection. This data acquisition (DAQ) system is designed around a custom protocol and hardware to achieve high data transfer rate and event-building capability without software overhead. In this paper, after a general outline of this DAQ system, we describe in detail the main features of controller. [ABSTRACT FROM AUTHOR]

Muon-induced single-event upset cross sections are estimated for a 28-nm static random access memory (SRAM) using Monte Carlo simulations informed by ion test results. As an exercise in modeling with limited information, details of the 28-nm SRAM’s cell structure were not used (and not available) to inform choices of device model parameters such as sensitive volume dimensions and efficiencies. Instead, inferences were made based on heavy-ion and proton single event upset data. Volume dimensions were sufficiently small to resolve the charge collection profile resulting from highly localized low linear energy transfer particle strikes. Results are compared to muon experimental data taken at TRIUMF for validation. Rate predictions are made for the 28-nm SRAM using the calibrated model and compared to expected neutron rates. Muon-induced upset rates at sea level for both marginally reduced and significantly reduced electrical biases, as well as rates at 39 000 feet, are predicted to be significantly less than neutron rates in all these environments. This result is consistent with other authors’ efforts in similarly scaled bulk CMOS SRAMs, indicating that the modeling method used is reliable. [ABSTRACT FROM PUBLISHER]

Time measurements play a crucial role in trigger and data acquisition systems of high-energy physics experiments, where synchronization between system elements, signal calibration, and phase-measurement accuracy is often required. In this paper, we present a fully digital time-to-digital converter (TDC) architecture and its application, based on a synthesizable digitally controlled oscillator (DCO), where the TDC is used to measure the phase relationship between a timing signal and a 40-MHz reference clock. The DCO design is technology independent; it is described by means of a hardware description language and it can be placed and routed with automatic tools. The TDC will be used in the new readout chip that is under development for the muon detector electronic upgrade in Large Hadron Collider beauty experiment at CERN. The TDC presented in this paper has the fundamental task of measuring, with a resolution of about 1.5 ns, the phase difference between the 40-MHz LHC machine clock and a digital signal coming from the muon detector. [ABSTRACT FROM PUBLISHER]

The muon-to-electron conversion experiment (Mu2e) at Fermilab is designed to explore charged lepton flavor violation. It is composed of three large superconducting solenoids: the production solenoid, the transport solenoid (TS), and the detector solenoid. The TS is formed by two magnets: TS upstream and TS downstream. Each has its own cryostat and power supply. Tolerance sensitivity studies of the position and angular alignment of each coil in this magnet system were performed in the past with the objective to demonstrate that the magnet design meets all the field requirements. The alignment of the cold masses is critical to maximize the transmission of muons and to avoid possible backgrounds that would reduce the sensitivity of the experiment. Each TS magnet cold mass can be individually aligned. In this paper, we discuss the implications of the alignment of the TS cold masses in terms of the displacement of the magnetic center. Consideration of the practical mechanical limits is also presented. [ABSTRACT FROM PUBLISHER]

KEK is currently constructing a long series of superconducting solenoid beamline for the COMET Phase-I experiment at the Hadron facility of J-PARC. The magnet system consists of a 5-T pion capture solenoid, a curved muon transport solenoid, and a large bore detector solenoid. The pion capture solenoid system consists of a large cold mass including four coils with an inner diameter of 1340 mm and a small cold mass including six small coils with an inner diameter of 500 mm. The peak magnetic field on the conductor reaches to 5.4 T at an operation current of 2700 A. This paper presents the design and structural details of a magnet, radiation-resistant coil, cold mass and vacuum vessel, apart from the results of the electromagnetic analysis in two-dimensional (2-D) and 3-D. [ABSTRACT FROM PUBLISHER]

We are developing a new technique to apply transition-edge sensors (TESs) to X-ray spectroscopy of exotic atoms, especially of kaonic atoms. To demonstrate the feasibility of this pioneering project, performance of a TES-based X-ray detector was evaluated in pion- and kaon-beam environments at particle accelerators. We successfully observed X-rays from pionic-carbon atoms with a resolution as good as 7 eV FWHM at 6 keV. Also at a kaon beamline, we confirmed that the TES spectrometer will be able to achieve our resolution goal, 6 eV, in our first scientific campaign to measure X-rays from kaonic-helium atoms. [ABSTRACT FROM AUTHOR]

Neutrinos play a fundamental role in the understanding of the origin of ultrahigh-energy cosmic rays. They interact through charged and neutral currents in the atmosphere generating extensive air showers. However, the very low rate of events potentially generated by neutrinos is a significant challenge for detection techniques and requires both sophisticated algorithms and high-resolution hardware. Air showers initiated by protons and muon neutrinos at various altitudes, angles, and energies were simulated in CORSIKA and the Auger OffLine event reconstruction platforms, giving analog-to-digital convertor (ADC) patterns in Auger water Cherenkov detectors on the ground. The proton interaction cross section is high, so proton “old” showers start their development early in the atmosphere. In contrast to this, neutrinos can generate “young” showers deeply in the atmosphere relatively close to the detectors. Differences between “old” proton and “young” neutrino showers are visible in attenuation factors of ADC waveforms. For the separation of “old” proton and “young” neutrino ADC traces, many three-layer artificial neural networks (ANNs) were tested. They were trained in MATLAB (in a dedicated way -only “old” proton and “young” neutrino showers as patterns) by simulated ADC traces according to the Levenberg–Marquardt algorithm. Unexpectedly, the recognition efficiency is found to be almost independent of the size of the networks. The ANN trigger based on a selected 8-6-1 network was tested in the Cyclone V E FPGA 5CEFA9F31I7, the heart of prototype front-end boards developed for testing new algorithms in the Pierre Auger surface detectors. [ABSTRACT FROM AUTHOR]

The KOTO experiment at J-PARC, Japan, aims to observe the rare neutral kaon decay mode KL\rightarrow \pi ^{0}\nu \bar {\nu } . After the first experimental run in May 2013 at a 24-kW beam power, the KOTO data acquisition (DAQ) system was upgraded in 2015 to provide efficient and reliable data collection at higher beam intensities. Lossless data compression in the analog-to-digital converter modules was implemented to reduce the size of data packets, resulting in a threefold increase in data collection rate. A new software trigger on a 47-node cluster was designed to use Infiniband hardware with message passing interface protocol to establish a mesh network inside the computer clusters for parallel data processing. The upgrade to the KOTO DAQ system was commissioned in 2015 and successfully collected data with a beam intensity of up to 42 kW. In preparation for increasing beam intensities in future runs, the hardware trigger upgrades using the reconfigurable clustering element platform technology are under development. [ABSTRACT FROM AUTHOR]

The operation of the compact muon solenoid drift tubes (DTs) muon detectors at the high-luminosity large hadron collider will be possible only with an upgrade of the current readout and trigger electronics, which are based on very old technology and directly exposed to radiation, hence particularly sensitive to aging. A new level 1 trigger primitive generator, based on the use of an original compact Hough transform (CHT) algorithm, is being designed with the goal of its implementation in the state-of-the-art field programmabla gate array (FPGA) devices. The algorithm can identify the muon track segment parameters and must be combined with a majority mean-timer in order to assign the muon to its parent bunch crossing. The algorithm is expected to be deployed on FPGAs and has a few \mu \texts latency for decision taking, with efficiency and resolution equal or higher with respect to the ones provided by the currently running algorithm. The major challenges are parallelization of the algorithm, fast readout of the CHT parameter matrix, the capability of handling data from a large array of DTs in the minimal number of FPGAs, and coping with the latency requirements. These issues will be addressed proposing constructive solutions. [ABSTRACT FROM AUTHOR]