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DOE OSTI2020

A New Scheme of Redundant Timing Crosschecking for Frontend Systems

In high energy physics experiments, frontend digitization modules are usually driven by a common clock. At the frontend electronics and digitization modules of the detector, a precise timing reference must establish in order to make a useful timing measurement. It would be very useful for the frontend digitization system to include a feature of redundant timing crosschecking. The inspiration for the timing crosschecking scheme came from the long-abandoned analog mean-timer schemes. In this scheme, several Front-end modules are connected together through a cable set with taps connected to the digitization modules. Pulses are driven from every FE modules alternately without overlapping. The arrival times of pulses sent from FE modules are digitized at the timing crosschecking module. The mean times will change as temperature changes, but their difference between two FE modules are cancelled mathematically. This feature enables easy achievement of good timing precision without the need for complex hardware.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

DOE OSTI2022

Jet timing

The measurement of the arrival time of a particle, such as a lepton, a photon, or a pion, reaching the detector provides valuable information. A similar measurement for a hadronic final state, however, is much more challenging as one has to extract the relevant information from a collection of particles. In this paper, we explore various possibilities in defining the time of a jet through the measurable arrival times of the jet constituents. We find that a definition of jet time based on a transverse momentum weighted sum of the times of the constituents has the best performance. For prompt jets, the performance depends on the jet trajectory. For delayed jets, the performance depends on the trajectory of the jet, the trajectory of the mother particle, and the location of the displaced vertex. Compared to the next-best-performing jet time definition, the transverse momentum weighted sum has roughly a factor of ten times better jet time resolution. We give a detailed discussion of the relevant effects and characterize the full geometrical dependence of the performance. These results highlight the critical importance of using a proper definition of jet time with its corresponding detector-dependent calibration and the exciting possibility of deepening our understanding of jets in the time domain.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2025

A High-Precision, Fast, Robust, and Cost-Effective Muon Detector Concept for the FCC-ee

We propose a high-precision, fast, robust and cost-effective muon detector concept for an FCC-ee experiment. This design combines precision drift tubes with fast plastic scintillator strips to enable both spatial and timing measurements. The drift tubes deliver two-dimensional position measurements perpendicular to the tubes with a resolution around 100~$\mu$m. Meanwhile, the scintillator strips, read out with the wavelength-shifting fibers and silicon photomultipliers, provide fast timing information with a precision of 200~ps or better and measure the third coordinate along the tubes with a resolution of about 1~mm.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

DOE OSTI2025

A sound horizon-free measurement of H 0 in DESI 2024

The physical size of the sound horizon at recombination is a powerful source of information for early-time measurements of the Hubble constant H 0 , and many proposed solutions to the Hubble tension therefore involve modifications to this scale. In light of this, there has been growing interest in measuring H 0 independently of the sound horizon. We present the first such measurement to use data from the Dark Energy Spectroscopic Instrument (DESI), jointly analyzing the full-shape galaxy power spectra of DESI luminous red galaxies, emission line galaxies, quasars, and the bright galaxy sample, in a total of six redshift bins. Information from the sound horizon scale is removed from our constraints via a rescaling procedure at the power spectrum level, with our sound horizon-marginalized measurement being driven instead primarily by the matter-radiation equality scale. This measurement is then combined with additional sound horizon-free information from Planck+ACT CMB lensing, uncalibrated type Ia supernovae, and the DESI Lyman-α forest. We agnostically combine with the DESY5, Pantheon+, and Union3 supernova datasets, with our tightest respective constraints being H 0 = 66.7 +1.7 -1.9 , 67.9 +1.9 -2.1 , and 67.8 +2.0 -2.2 km s -1 Mpc -1 . This corresponds to a sub-3% sound horizon-free constraint of the Hubble constant, and is the most precise measurement of its kind to date. Even without including information from the sound horizon, our measurement is still in 2.2-3.0σ tension with SH0ES. Additionally, the consistency between our result and other measurements that do rely on the sound horizon scale provides no evidence for new early-Universe physics (e.g. early dark energy). Future DESI data releases will allow unprecedented measurements of H 0 and place strong constraints on models that use beyond-ΛCDM physics to ameliorate the Hubble tension.

79 ASTRONOMY AND ASTROPHYSICS↗

NASA NTRS2021

Refining the Transit Timing and Photometric Analysis of TRAPPIST-1: Masses, Radii, Densities, Dynamics, and Ephemerides

We have collected transit times for the TRAPPIST-1 system with the Spitzer Space Telescope over four years. We add to these ground-based, HST, and K2 transit-time measurements, and revisit an N-body dynamical analysis of the seven-planet system using our complete set of times from which we refine the mass ratios of the planets to the star. We next carry out a photodynamical analysis of the Spitzer light curves to derive the density of the host starand the planet densities. We find that all seven planets’ densities may be described with a single rocky mass–radius relation which is depleted in iron relative to Earth, with Fe 21 wt% versus 32 wt% for Earth, and otherwise Earth-like in composition. Alternatively, the planets may have an Earth-like composition but enhanced in light elements,such as a surface water layer or a core-free structure with oxidized iron in the mantle. We measure planet masses toa precision of 3%–5%, equivalent to a radial-velocity(RV)precision of 2.5 cm s−1, or two orders of magnitude more precise than current RV capabilities. We find the eccentricities of the planets are very small, the orbits are extremely coplanar, and the system is stable on 10 Myr timescales. We find evidence of infrequent timing outliers, which we cannot explain with an eighth planet; we instead account for the outliers using a robust likelihood function. We forecast JWST timing observations and speculate on possible implications of the planet densities forthe formation, migration, and evolution of the planet system.

Eric Agol↗

NASA NTRS1972

Operational characteristics of a translation screen grid beam deflection system for a 5-cm Kaufman thruster

Measurements of beam deflection angle with respect to spring positioning power and accelerator impingement current as a function of deflection angle were made on a 5-cm diameter system. Response time measurements on the translational grid beam deflection system showed that the time for the maximum deflection angle analyzed (+16.4 deg to -16.4 deg) could be reduced by a factor of nine by increasing the heating power applied to the positioning spring from 4 to 16 watts. At 14 watts the response time for maximum deflection was about 1 minute.

Lathem, W. C.↗

DOE OSTI2023

Time-walk and jitter correction in SNSPDs at high count rates

Superconducting nanowire single-photon detectors (SNSPDs) are a leading detector type for time correlated single photon counting, especially in the near-infrared. When operated at high count rates, SNSPDs exhibit increased timing jitter caused by internal device properties and features of the RF amplification chain. Variations in RF pulse height and shape lead to variations in the latency of timing measurements. To compensate for this, we demonstrate a calibration method that correlates delays in detection events with the time elapsed between pulses. The increase in jitter at high rates can be largely canceled in software by applying corrections derived from the calibration process. We demonstrate our method with a single-pixel tungsten silicide SNSPD and show it decreases high count rate jitter. The technique is especially effective at removing a long tail that appears in the instrument response function at high count rates. At a count rate of 11.4 MCounts/s, we reduce the full width at 1% maximum level (FW1%M) by 45%. The method, therefore, enables certain quantum communication protocols that are rate-limited by the FW1%M metric to operate almost twice as fast.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

DOE OSTI2021

Spatiotemporal characterization of the field-induced insulator-to-metal transition

Watching a metal filament grow Resistive switching is a process in which the electrical resistance of a sample changes abruptly in response to a voltage pulse, often by orders of magnitude. This process is at the heart of many neuromorphic computing approaches but visualizing it in both space and time is tricky. del Valle et al . monitored the resistive switching in three different vanadium oxide compounds by measuring time- and space-resolved optical reflectivity (see the Perspective by Hilgenkamp and Gao). A characteristic conducting filament was quickly nucleated on the inhomogeneities in the sample and then propagated due to Joule heating. —JS

Science & Technology - Other Topics↗

NASA NTRS1977

Optical timing receiver for the NASA laser ranging system. Part 2: High precision time interval digitizer

The development of a high precision time interval digitizer is described. The time digitizer is a 10 psec resolution stop watch covering a range of up to 340 msec. The measured time interval is determined as a separation between leading edges of a pair of pulses applied externally to the start input and the stop input of the digitizer. Employing an interpolation techniques and a 50 MHz high precision master oscillator, the equivalent of a 100 GHz clock frequency standard is achieved. Absolute accuracy and stability of the digitizer are determined by the external 50 MHz master oscillator, which serves as a standard time marker. The start and stop pulses are fast 1 nsec rise time signals, according to the Nuclear Instrument means of tunnel diode discriminators. Firing level of the discriminator define start and stop points between which the time interval is digitized.

Leskovar, B.↗

NASA NTRS1986

The Lidar In-Space Technology Experiment (LITE)

A spaceborne lidar system is presently being constructed for flight aboard the U. S. Space Shuttle in early 1991. The experiment, Lidar In Space Technology Experiment (LITE), utilizes a neodymium:YAG laser and 0.85 meter effective diameter Cassegranian-configured telescope receiver for making elastic backscatter measurements. The laser will be frequency doubled and tripled simulataneously producing a 10 Hz rate of 200 mJ at 1064 nm, 400 mJ at 532 nm, and 150 mJ at 355 nm. The technological objectives of LITE are to evaluate lidar system operations in space, lidar techniques in space, and to provide a test bed for new lidar technologies in later flights. The measurement objectives include the determination of cloud top and planetary boundary layer heights, the measurement of tropospheric and stratospheric aerosols, and the measurement of temperature and density between 10 to 40 km altitude. Detailed simulations will be presented showing the errors associated with each of these measurement objectives. In addition, the experiment scenario will be described including measurement times, data flow, processing and archival, and initial plans for validation of the LITE data set with correlative measurements.

Mccormick, M. P.↗

NASA NTRSDate not supplied

Space Weather Investigation Frontier (SWIFT)

Continuous, in-situ, multi-point observations along the Sun-Earth line at and inside the Lagrange point L1 (sub-L1) will enable a better understanding of the three-dimensional structure and temporal evolution of heliospheric structures that drive terrestrial space weather. The proposed SWIFT (Space Weather Investigation Frontier) mission will use a new solar sail propulsion system developed by NASA to enable a suite of science instruments onboard a smallsat to maintain observations along the Sun-Earth line, sub-L1, for extended periods. Three identically instrumented small spacecraft at L1 will fly in concert with the sailcraft at sub-L1in an optimized tetrahedron constellation, covering distances between 10 to 100’s of Earth radii. This viewing geometry will enable scientists to distinguish between local and global processes driving space weather by revealing the spatial characteristics, temporal evolution, and geo-effectiveness of small-to meso-scale solar wind structures and substructures of macro-scale structures, such as interplanetary coronal mass ejections (ICMEs) and stream interaction regions (SIRs). In addition, real time measurements of earth-bound heliospheric structures from sub-L1 will improve our current forecasting lead-times by up to 35 percent. This paper will provide an overview of the proposed SWIFT science and mission concept.

Heliophysics↗

DOE OSTI2023

Implementation of a System of Gamma Imagers for Measuring Plutonium Holdup

The Surplus Plutonium Disposition (SPD) project is an effort to dilute and dispose of many tonsof weapons grade plutonium. This work will take place in a shielded glovebox to protect workers fromradiological dose. Accurate measurements of the holdup, or material left behind, in the gloveboxes is im-portant for Nuclear Material Control and Accountancy, worker dose minimization, criticality safety, andprocess monitoring. Shielding around the gloveboxes presents an obstacle for the traditional GeneralizedGamma Holdup (GGH) method. The uncertainties associated with that method, at around 28%, arealso detrimental since the amount of holdup must be kept below an established limit with a high level ofconfidence.Passive gamma-ray imaging provides a more complete depiction of the distribution of radioactivematerials. Recent refinement of the method has demonstrated that quantitative information can beextracted from the images with a well-characterized system. A permanently installed system of gamma-ray imagers is currently being developed to measure plutonium holdup in the SPD gloveboxes. Thispaper will report on progress with the development of this system.This application requires that the features of current commercially available instruments from H3Dand PHDS, optimized for measurement performance in a mobile application, be translated into theconstraints of the operational environment with fixed installations. The interaction between facilityconstraints and measurement capabilities will be addressed.A series of measurements with plutonium sources in a mocked-up glovebox geometry with imagersmounted above the ceiling of the glovebox have been taken. Imager performance with respect to angularresolution, minimum measurement time for quantification, and signal-to-noise ratio with a multitudeof sources will be evaluated for those measurements. A series of prototypes of user interfaces will bepresented for display of the data to its various consumers for the purposes of Nuclear Material Controland Accountancy, worker dose minimization, criticality safety, and process monitoring.

Schmitt, Kyle↗

NASA NTRS1987

Flow measurements in a water tunnel using a holocinematographic velocimeter

Dual-view holographic movies were used to examine complex flows with full three-space and time resolution. This approach, which tracks the movement of small tracer particles in water, is termed holocinematographic velocimetry (HCV). A small prototype of a new water tunnel was used to demonstrate proof-of-concept for the HCV. After utilizing a conventional flow visualization apparatus with a laser light sheet to illuminate tracer particles to evaluate flow quality of the prototype tunnel, a simplified version of the HCV was employed to demonstrate the capabilities of the approach. Results indicate that a full-scale version of the water tunnel and a high performance version of the HCV should be able to check theoretical and numerical modeling of complex flows and examine the mechanisms operative in turbulent and vortex flow control concepts, providing an entirely unique instrument capable, for the first time, of simultaneous three-space and time measurements in turbulent flow.

Weinstein, Leonard M.↗

NASA NTRS1974

Observations of low energy hydrogen and helium isotopes during solar quiet times

Results of a new quiet-time measurement of the relative abundance of cosmic-ray H-2 and He-4. The observations were made in selected time intervals between September 1972 and February 1973 with the Caltech Electron/Isotope Spectrometer on IMP-7. In the energy interval from 13 to 29 MeV/nucleon, an upper limit to the H-2 to He-4 ratio of less than 0.06 is found. This new upper limit is significantly lower than finite H-2/He-4 ratios measured in earlier years by other workers. Possible implications of this new result are discussed.

Hurford, G. J.↗

DOE OSTI2021

Effect of Auger recombination on transient optical properties in XUV and soft X-ray irradiated silicon nitride

Spatially encoded measurements of transient optical transmissivity became a standard tool for temporal diagnostics of free-electron-laser (FEL) pulses, as well as for the arrival time measurements in X-ray pump and optical probe experiments. The modern experimental techniques can measure changes in optical coefficients with a temporal resolution better than 10 fs. This, in an ideal case, would imply a similar resolution for the temporal pulse properties and the arrival time jitter between the FEL and optical laser pulses. However, carrier transport within the material and out of its surface, as well as carrier recombination may, in addition, significantly decrease the number of carriers. This would strongly affect the transient optical properties, making the diagnostic measurement inaccurate. Below we analyze in detail the effects of those processes on the optical properties of XUV and soft X-ray irradiated Si 3 N 4 , on sub-picosecond timescales. Si 3 N 4 is a wide-gap insulating material widely used for FEL pulse diagnostics. Theoretical predictions are compared with the published results of two experiments at FERMI and LCLS facilities, and with our own recent measurement. The comparison indicates that three body Auger recombination strongly affects the optical response of Si 3 N 4 after its collisional ionization stops. By deconvolving the contribution of Auger recombination, in future applications one could regain a high temporal resolution for the reconstruction of the FEL pulse properties measured with a Si 3 N 4 -based diagnostics tool.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗

DOE OSTI2026

The Effects of Beta Irradiation on the Performance of ATR Fiber Probes

The use of real-time inline monitoring to track the chemical composition of slurries is recognized as a promising method to reduce the processing time of Hanford tank waste. The conversion of waste into glass suitable for long-term storage requires adherence to waste acceptance criteria and process control limits that respectively ensure safe operation of the vitrification facility and suitable glass quality. Real-time measurements of blended waste materials can ensure that the various criteria are met or can be addressed in a timely manner.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

NASA NTRS1983

A helium-3 refrigerator employing capillary confinement of liquid cryogen

A condensation refrigerator suitable for operation in a zero gravity space environment was constructed. The condensed liquid refrigerant is confined by surface tension inside a porous metal matrix. Helium-4 and helium-3 gases were condensed and held in a copper matrix. Evaporative cooling of confined liquid helium-4 resulted in a temperature of 1.4K. Using a zeolite adsorption pump external to the cryostat, a temperature of 0.6 K was achieved through evaporative cooling of liquid helium-3. The amount of time required for complete evaporation of a controlled mass of liquid helium-4 contained in the copper matrix was measured as a function of the applied background power. For heating powers below 18 mW the measured times are consistent with the normal boiling of the confined volume of liquid refrigerant. At background powers above 18 mW the rapid rise in the temperature of the copper matrix the signature of the absence of confined liquid occurs in a time a factor of two shorter than that expected on the basis of an extrapolation of the low power data.

Ennis, D. J.↗

NASA NTRS1991

Large area QNDE inspection for airframe integrity

Quantitative Nondestructive Evaluation (QNDE) technology is being developed to provide new options for cost effective inspection of airframes. An R&D effort based on five NDE technologies is addressing questions of structural bonding assessment, corrosion detection, multisite damage detection, and fatigue characterization. The research/applications are being conducted by prioritized focussing and staging of the following technologies: (1) thermal NDE; (2) ultrasonic NDE; (3) coherent optical NDE; (4) magnetic imaging NDE; and (5) radiographic NDE. The focus here is on the most recent applications of thermal NDE technology to large area inspection of lap-joint and stiffener bonds. The approach is based on pulsed radiant heating of the airframe and measurement of the surface temperature of the structure with an infrared imager. Several advantages of the technique are that it is noncontacting, inspects one square meter area in a period of less than 2 minutes and has no difficulty inspecting typical curvatures of the fuselage. Numerical models of heat flow in these geometries are used to determine appropriate techniques for reduction of the infrared images, thereby delineating regions of disbonds. These models are also used to determine the optimum heating and measurement times for maximizing the contrast between bonded and unbonded structures. Good agreement is found between these results and experimental measurements, and a comparison of the two are presented. Also presented are results of measurements on samples with fabricated defects which show the technique is able to clearly indicate regions of disbonds. Measurements on an airframe also clearly image subsurface structure.

Winfree, William P.↗