Single Event Sensitivity Research Articles

First results on the K+ → π+vv¯ decay search from NA62

The precise measurement of the branching ratio of an ultrarare decay K+ → π+vv¯ (~10-10 according to the calculation within the Standard Model) allows to probe New Physics via indirect effects at mass scales higher than those accessible at the LHC. The NA62 experiment at the CERN SPS is aimed at measuring this branching ratio with the 10% precision. To achieve such level of precision, a novel decay-in-flight technique is used. The statistics collected during the first NA62 physics run in 2016 allowed to demonstrate the proof of the experimental method and obtain O(10-10) single event sensitivity. The preliminary results based on the 2016 data set are described.

Single event sensitivity analysis of bandgap reference

Single event sensitivity analysis of bandgap reference

The Mu2e experiment at Fermilab: a search for lepton flavor violation

The Mu2e experiment at Fermilab will search for the charged lepton flavor violating process of neutrino-less μ→e coherent conversion in the field of an aluminum nucleus. About 7 ⋅ 1017 muons, provided by a dedicated muon beam line in construction at Fermilab, will be stopped in 3 years in the aluminum target. The corresponding single event sensitivity will be 2.5⋅10−17. In this paper a brief overview of the physics explored by the μ→e conversion is given, followed by a description of the Mu2e experimental apparatus and the expected detector performance.

The full stereo drift chamber for the MEG II experiment

The MEG experiment, at the Paul Scherrer Institute (PSI) near Zurich in Switzerland, aims at searching for the charged-lepton-flavor-violating decay μ+arrow e+γ, prohibited in the Standard Model but allowed, at a measurable level, in many of its extensions. MEG has already determined the world best upper limit on the branching ratio: BR(μ+arrow e+γ)<4.2×10−13 at 90% CL with the full data set collected in the years 2009–2013. A further improvement of the MEG single event sensitivity requires a substantial upgrade of the detector performances and, in particular, the complete replacement of the positron tracker. The MEG upgrade experiment (MEG II) is currently under construction and it is conceived in order to further improve the sensitivity by one order of magnitude in three years of data taking. The new positron tracker is a high transparency single volume, full stereo cylindrical Drift Chamber, immersed in a non uniform longitudinal B-field, co-axial to the muon beam line. Due to the high wire density (12 wires/cm2), the use of the traditional feed-through technique as wire anchoring system could hardly be implemented and therefore it was necessary to develop new wiring strategies. The number of wires and the stringent requirements on the precision of their position and on the uniformity of the wire mechanical tension impose the use of an automatic system to operate the wiring procedures. The drift chamber is currently under construction at INFN Lecce and Pisa, and should be completed by the summer 2017 to be then delivered to PSI for commissioning. The upgraded detector, the new drift chamber and its construction technique, will be described.

Analysis of Single-Event Effects in a Radiation-Hardened Low-Jitter PLL Under Heavy Ion and Pulsed Laser Irradiation

A radiation-hardened low-jitter phase-locked loop (PLL) with a low-mismatch charge pump and a robust voltage-controlled oscillator is designed in a 130 nm PD-SOI process. In order to evaluate the overall response to single-event effects, the accumulated phase jitter has been put forward, which can exclude the inherent noise floor and accumulate all the radiation-induced noise. Then the single-event sensitivity of the proposed PLL is comprehensively analyzed by heavy ion and pulsed laser tests.

Effects of Temperature and Supply Voltage on SEU- and SET-Induced Errors in Bulk 40-nm Sequential Circuits

The single-event sensitivity of bulk 40-nm sequential circuits is investigated as a function of temperature and supply voltage. An overall increase in SEU cross section versus temperature is observed at relatively high supply voltages. However, at low supply voltages, there is a threshold temperature beyond which the SEU cross section decreases with further increases in temperature. Single-event transient induced errors in flip-flops also increase versus temperature at relatively high supply voltages and are more sensitive to temperature variation than those caused by single-event upsets.

Design and status of the Mu2e electromagnetic calorimeter

The Mu2e experiment at Fermilab aims at measuring the neutrinoless conversion of a negative muon into an electron and reach a single event sensitivity of 2.5×10−17 after three years of data taking. The monoenergetic electron produced in the final state, is detected by a high precision tracker and a crystal calorimeter, all embedded in a large superconducting solenoid (SD) surrounded by a cosmic ray veto system. The calorimeter is complementary to the tracker, allowing an independent trigger and powerful particle identification, while seeding the track reconstruction and contributing to remove background tracks mimicking the signal. In order to match these requirements, the calorimeter should have an energy resolution of O(5)% and a time resolution better than 500ps at 100MeV. The baseline solution is a calorimeter composed of two disks of BaF2 crystals read by UV extended, solar blind, Avalanche Photodiode (APDs), which are under development from a JPL, Caltech, RMD consortium. In this paper, the calorimeter design, the R&D studies carried out so far and the status of engineering are described. A backup alternative setup consisting of a pure CsI crystal matrix read by UV extended Hamamatsu MPPC׳s is also presented.

Evaluating the single event sensitivity of dynamic comparator in 5 Gbps SerDes

Evaluating the single event sensitivity of dynamic comparator in 5 Gbps SerDes

An Investigation of Single-Event Transients in C-SiGe HBT on SOI Current Mirror Circuits

The single-event effect sensitivity of three different commonly employed current mirror circuits, as well as an unconventional inverse-mode current mirror, all implemented in C-SiGe (NPN + PNP) HBT on SOI technology are investigated. Comparisons of the measured data of the basic NPN and PNP current mirror circuits show higher single-event radiation tolerance of PNP SiGe HBTs compared with NPN SiGe HBTs. The concept of utilizing inverse-mode SiGe HBTs in current mirror circuits is investigated. Measurement results validate the feasibility of employing inverse-mode PNP SiGe HBTs in current mirrors and show an excellent resilience against ion-strikes. Full 3-D NanoTCAD models of the SiGe HBTs are developed and used in mixed-mode TCAD simulations (within Cadence) to validate the measurement results. Finally, based on the measurement data and analysis of the four current mirrors, some practical suggestions and observations are offered for operation of such circuits in extreme environments.

Simulation study of N-hit SET variation in differential cascade voltage switch logical circuits

The advancement in the process leads to more concern about the Single Event (SE) sensitivity of the Differential Cascade Voltage Switch Logic (DCVSL) circuits. The simulation results indicate that the Single Event Transient (SET) generated at the DCVSL gate is much larger than that at the ordinary CMOS gate, and their SET variation is different. Based on charge collection, in this paper, the effective collection time theory is proposed to set forth the SET pulse generated at the DCVSL gate. Through 3D TCAD mixed-mode simulation in 65 nm twin-well bulk CMOS process, the effects on SET variation of device parameters such as well contact size and environment parameters such as voltage are investigated.

A two-stage approach in the the search for μ – e conversion with COMET

The COMET experiment will search for the charged lepton flavour violating process μ− + N(Z,A) → e− + N(Z,A) in Al with a single event sensitivity of 3 × 10−17. This will be a four orders of magnitude improvement on the current limit set by SINDRUM-II in Au. The design, R&D and construction of COMET are all well underway and described here is an update on the current status of the experiment.

Muon-to-Electron Conversion with COMET

The Coherent Muon-to-Electron Transition (COMET) experiment ispresented, focusing on the particle detection systems. COMET is currentlyunder construction as the first of two phases at the J-PARC protonaccelerator laboratory in Tokai, Japan. COMET will search formuon-to-electron conversion with a single-event sensitivity of 2.6 × 10−17, with Phase-I achievinga sensitivity of 3.1 × 10−15 and due to enter commissioning in 2016. Phase-I will also allow us to studythe novel pion and muon beamline and the rates of background processes.

A Two-Stage Approach in the Search for [formula omitted] Conversion with COMET

The COMET experiment will search for the charged lepton flavour violating process μ−+N(Z,A)→e−+N(Z,A) with an ultimate single event sensitivity of 3×10−17. Design, R&D and construction are all well underway and described here is an update on the current status of the experiment.

Mu2e: a Muon to Electron Conversion Experiment at Fermilab

We present the status of Mu2e, a proposed experiment to measure the rate of muon to electron conversion in the field of a nucleus. The Mu2e experiment will be hosted by Fermilab at a new muon campus, using a new beamline to deliver protons to the muon generation target. Mu2e will use a series of three solenoids to collect, transport, stop, and analyze the muons produced when the 8 GeV pulsed proton beam from the booster hits the tungsten production target. The 200 nsec wide proton pulse is designed to have a ratio of out-of-time to in-time protons better than 10−10, insuring a measurement time window of approximately 1 microsecond essentially free from beam pion background. A precision, low-mass straw tube tracker will measure electron momenta with a precision of 1/1000, allowing clean separation of the conversion signal from Decay In Orbit electrons, the principle experimental background. Extensive coverage of multi-layer scintillation counters will detect 99.99% of the cosmic muons which could generate fake signals. A crystal calorimeter will provide particle ID to further reduce backgrounds. Detailed simulations show a 3-year run with 7.56×1017 stopped muons will allow a Single Event Sensitivity of 2×10−17, allowing an estimated 90% confidence level sensitivity to Rμe of 6×10−17, a four-orders of magnitude improvement over existing limits. The Mu2e schedule is technically limited, with commissioning beginning in 2019. Mu2e may also run at Project X with 10× higher luminosity using either an aluminum or titanium target after minimal upgrades.

DeeMe experiment – An experimental search for a mu-e conversion reaction at J-PARC MLF

A new experiment searching for a mu-e conversion in nuclear field is going to be conducted at J-PARC Material Life Science Facility. Expected single event sensitivity of the experiment is 2×10−14 with 1MW accelerator operation and 2×107s data taking. Electron spectrometer is planned to be composed of low mass thin gap multi wire proportional chambers and research and development works with the prototype detector is performed.

Nuclear aspects of neutral current non-standard ν-nucleus reactions and the role of the exotic [formula omitted] transitions experimental limits

The nuclear aspects of flavour changing neutral current (FCNC) processes, predicted by various new-physics models to occur in the presence of nuclei, are examined by computing the relevant nuclear matrix elements within the context of the quasi-particle RPA using realistic strong two-body forces. One of our aims is to explore the role of the non-standard interactions (NSI) in the leptonic sector and specifically: (i) in lepton flavour violating (LFV) processes involving the neutral particles νℓ and ν˜ℓ, ℓ=e,μ,τ and (ii) in charged lepton flavour violating (cLFV) processes involving the charged leptons ℓ− or ℓ+. As concrete nuclear systems we have chosen the stopping targets of μ−→e− conversion experiments, i.e. the 48Ti nucleus of the PRIME/PRISM experiment at J-PARC and the 27Al of the COMET at J-PARC as well as of the Mu2e at Fermilab. These experiments have been designed to reduce the single event sensitivity down to 10−16–10−18 in searching for charged lepton mixing events. Our goal is, by taking advantage of our detailed nuclear structure calculations and using the present limits or the sensitivity of the aforementioned exotic μ−→e− experiments, to put stringent constraints on the parameters of NSI Lagrangians.

An Investigation of Single-Event Effects and Potential SEU Mitigation Strategies in Fourth-Generation, 90 nm SiGe BiCMOS

The single-event effect sensitivity of fourth-generation, 90 nm SiGe HBTs is investigated. Inverse-mode, ≥1.0 Gbps SiGe digital logic using standard, unoptimized, fourth-generation SiGe HBTs is demonstrated and the inverse-mode shift register exhibited a reduction in bit-error cross section across all ion-strike LETs. Ion-strike simulations on dc calibrated, 3-D TCAD SiGe HBT models show a reduction in peak current transient magnitude and a reduction in overall transient duration for bulk SiGe HBTs operating in inverse mode. These improvements in device-level SETs are attributed to the electrical isolation of the physical emitter from the subcollector-substrate junction and the high doping in the SiGe HBT base and emitter, suggesting that SiGe BiCMOS technology scaling will drive further improvements in inverse-mode device and circuit-level SEE. Two-photon absorption experiments at NRL support the transient mechanisms described in the device-level TCAD simulations. Fully-coupled mixed-mode simulations predict large improvements in circuit-level SEU for inverse-mode SiGe HBTs in multi-Gbps, inverse-mode digital logic.

Single-Event Response of the SiGe HBT Operating in Inverse-Mode

The single-event effect sensitivity of inverse-mode biased SiGe HBTs in both bulk and SOI technology platforms are investigated, for the first time, using digital circuits and stand-alone device test structures. Comparisons of heavy-ion broad beam data of shift register circuits constructed with forward-mode and inverse-mode biased SiGe HBTs from a first-generation, complementary SOI SiGe BiCMOS process, reveal an improvement in SEU mitigation for the inverse-mode shift register architecture. Full 3D TCAD simulations highlight the differences in transient current origination between forward and inverse-mode biased devices, illustrating the impact of doping profiles on ion-induced shunt duration. To extend the analysis to a bulk platform, new fourth-generation npn , SiGe HBTs were biased in both the forward and inverse-mode and irradiated at NRL using the two photon absorption measurement system. These measurements support the analysis of transient origination using 3D TCAD simulations. Furthermore, the isolation of the output terminal from the sensitive subcollector-substrate junction is experimentally demonstrated for the inverse-mode bias. Fully coupled mixed-mode simulations predict a significant reduction in sensitive area for inverse-mode shift registers built in a bulk SiGe platform.

Mu2e: A high-sensitivity search for charged lepton flavor violation at Fermilab

The Mu2e collaboration proposes to search for the coherent, neutrinoless conversion of muons into electrons in the field of a nucleus, μ − N → e − N , with a single-event sensitivity of ∼ 10 − 16 , an improvement of a factor of 10,000 over existing limits. This lepton flavor-violating reaction probes mass scales unavailable by direct searches at either present or planned high energy colliders. The apparatus is described as well as a scheme by which the experiment can be mounted in the present Fermilab accelerator complex. Prospects for increased sensitivity using the Project X accelerator upgrades that are being proposed by Fermilab are briefly discussed.

Phase-Dependent Single-Event Sensitivity Analysis of High-Speed A/MS Circuits Extracted from Asynchronous Measurements

A method for experimental determination of the phase dependence of single-event sensitivity in high-speed A/MS circuits is presented. The technique ensures testing coverage of the complete data cycle and results in a correlation of errors to the data or clock cycle of the circuit. Designers can apply the information, along with knowledge of the circuit state at the time of errors, to make informed radiation-hardening-by-design decisions.