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At least 289 records · Page 16

The Gas Chromatograph Mass Spectrometer for the Huygens Probe

Titan is unique in the solar system, the only moon that has a dense atmosphere. The major constituents of the atmosphere, nitrogen and methane, are continuously broken apart by a combination of solar UV, impinging electrons from Saturn's magnetosphere, and a steady flow of cosmic rays. The resulting molecular fragments recombine and form a variety of new species, many of which were detected for the first time by Voyager 1. The ubiquitous, surface-hiding aerosol blanket manifests the existence of still more complex compounds. In addition to hydrocarbons and nitriles, the atmosphere is known to contain CO, CO2 and externally delivered H2O. The Gas Chromatograph Mass Spectrometer (GCMS) on the Huygens Probe will measure the chemical composition of the atmosphere of Titan from 170 km altitude (approximately lhPa) to the surface (approximately 1500hPa) and determine the isotope ratios of the major constituents. The GCMS will also analyze gas samples from the Aerosol Collector Pyrolyser (ACP) and may be able to obtain compositional information of several surface materials. The GCMS consists of a quadrupole mass spectrometer (QP) with a secondary electron multiplier ion detector, a three-column gas chromatograph (GC) and an elaborate gas sampling system. The gas sampling system will provide atmospheric samples to the QP for nearly continuous analysis during the Probe descent and batch samples at several altitudes for GC analysis. It also contains a chemical scrubber for noble gas analysis and an enrichment cell for trace constituent enhancement. In addition to the sampling of the atmosphere periodic gas samples, derived from the pyrolysis of aerosols, will be transferred from the ACP to the GCMS for direct QP and full GCMS analysis. The QP can analyze molecular masses from 2 to 14lDalton. The nominal detection threshold is at a mixing ratio of 10E-8. Data rate is 885 bits/sec. The mass of the instrument is 17.3 kg and the energy required for operation during the descent is 110 Watt-hours.

Niemann, H. B.↗

Commercially available Hydrogen Detection Systems for Corrosive, Oxygen-free Gas Streams: A Technical Summary

The growing use of hydrogen gas across energy, transportation, and chemical applications necessitates better hydrogen sensors and detectors. Few sensors exist for quantifying hydrogen gas in a corrosive, oxygen-free gas stream due to the challenging nature of the sampling environment and current technological status. Handheld, economic options include palladium-based, metal oxide, catalytic bead, and electrochemical sensors. More permanent and costly options include electrochemical sensors, thermal gas analyzers, mass spectrometers, gas chromatographs, and Raman spectrometers. In this technical report, a short review of current technology, along with the associated commercially available products, is provided. Raman spectroscopy is recommended as an ideal technology for on-line detection of hydrogen at low concentrations in a corrosive, oxygen-free gas stream.

08 HYDROGEN↗

Prospects for high pressure imaging gas scintillation drift chambers

The current developmental status and future potential of a promising hard X-ray and gamma ray detector are presented: the high pressure xenon gas scintillation imaging drift chamber. A scheme for reading out the scintillation light waveshifting fibers, which allows operation at pressures at least as high as 20 atmospheres, is used. This technique combines excellent spatial resolution (approximately 200 rms allowing 1.5 arcminute mapping resolution), very good energy resolution (within a factor of three of Ge detectors), good time resolution (approximately 100 ns), and extremely high sensitivity because of excellent background rejection capabilities; it also offers possibilities for extrapolation to large area detectors. Results from tests with a prototype chamber are presented. The design of a scientific instrument for a balloon flight planned in 1995 is described. This instrument, the Scintillation Imaging Gas filled Hard X-ray Telescope (SIGHT), is optimized for detecting 30 to 300 keV X-rays. It has an active area of 1140 sq cm, with a stopping power of between 2.0 and 2.7 g/sq cm of xenon at 20 atmospheres. Possible future evolutionary tracks of the technology leading to innovative satellite applications are discussed.

Edberg, T. K.↗

Development of a new CEDAR for kaon identification at the NA62 experiment at CERN

The NA62 experiment at CERN utilises a differential Cherenkov counter with achromatic ring focus (CEDAR) for tagging kaons within an unseparated monochromatic beam of charged hadrons. The CEDAR-H detector was developed to minimise the amount of material in the path of the beam by using hydrogen gas as the radiator medium. The detector was shown to satisfy the kaon tagging requirements in a test-beam before installation and commissioning at the experiment. The CEDAR-H performance was measured using NA62 data collected in 2023.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

Performance of a multistep fluorescence-gated proportional counter for hard X-ray astronomy

Results from the first flight of our proportional counter in an imaging telescope led us to rebuild the detector. We have used a Penning gas mixture (xenon + 1 percent isobutylene) and introduced a preamplification region to improve the energy resolution. We have rebuilt the pressure vessel making novel use of molybdenum as the housing material in order to reduce the residual instrument background, particularly in the fluorescence-gated mode for which the detector design has been optimized. We have also increased the sensitive gas depth from 9 to 14 cm to further increase the sensitivity to both fluorescent pairs and conventional singles. Our calibrations have shown that the overall energy resolution of the detector has been enhanced by a factor of 2, and we predict that the sensitivity at float will increase by a factor of 3 in the 50-70 keV energy band.

Dietz, K. L.↗

Machine learning for single-ended event reconstruction in PROSPECT experiment

The Precision Reactor Oscillation and Spectrum Experiment, PROSPECT, was a segmented antineutrino detector that successfully operated at the High Flux Isotope Reactor in Oak Ridge, TN, during its 2018 run. Despite challenges with photomultiplier tube base failures affecting some segments, innovative machine learning approaches were employed to perform position and energy reconstruction, and particle classification. This work highlights the effectiveness of convolutional neural networks and graph convolutional networks in enhancing data analysis. By leveraging these techniques, a 3.3% increase in effective statistics was achieved compared to traditional methods, showcasing their potential to improve analysis performance. Furthermore, these machine learning methodologies offer promising applications for other segmented particle detectors, underscoring their versatility and impact.

47 OTHER INSTRUMENTATION↗

A rocket borne instrument for the study of soft X-ray emission from cosmic X-ray sources

Details about a rocket-borne instrument designed for studying the various characteristics of soft X-ray emission from cosmic X-ray sources in the energy range of 0.2 to 3 keV are presented. The X-ray detector consists of a bank of four multilayer, wall-less proportional counters, each with an area of 400 sq cm. The detectors are covered by windows of 1.4-micron polypropylene and are maintained at a constant pressure in flight using a gas control system. Two of the detectors are equipped with 0.4- by 10-deg collimators for mapping the spatial distribution of soft X-rays from extended X-ray sources. A pair of balanced filters consisting of oxygen and CF4 are used for detecting oxygen emission lines.

Agrawal, P. C.↗

The high energy cosmic ray detector for Spacelab II

A large cosmic ray detector to be flown on Spacelab II is presently under construction at the University of Chicago. The instrument, with a geometric factor of 5 sq m-ster, is designed to measure the elemental composition and the energy spectra of individual cosmic ray nuclei (Li to Fe) from 50 GeV/nucleon to several TeV/nucleon. Plastic scintillators are used for charge determination, and gas Cerenkov and transition radiation detectors for energy measurements. The instrument and its functions are described, and several test results that are important for an optimum design are discussed.

Lamport, J. E.↗

System and Method for Determining Fluence of a Substance

A system and method for measuring a fluence of gas are disclosed. The system has a first light detector capable of outputting an electrical signal based on an amount of light received. A barrier is positionable adjacent the first light detector and is susceptible to a change in dimension from the fluence of the gas. The barrier permits a portion of light from being received by the first light detector. The change in the dimension of the barrier changes the electrical signal output from the first light detector. A second light detector is positionable to receive light representative of the first light detector without the barrier. The system and method have broad application to detect fluence of gas that may cause erosion chemical reaction causing erosive deterioration. One application is in low orbit Earth for detecting the fluence of atomic oxygen.

Banks, Bruce A.↗

Interchange for Joint Research Entitled: Miniature Laser Spectrometer for Stable Isotope Measurements

As a first step in successfully measuring carbon isotopes optically we have previously demonstrated the measurement of C-13/C-12 to a precision of 0.1% using a tunable diode laser and CO2 spectral lines in the 2300/cm spectral region. This precision of 0.1% (1 per mil) for carbon isotopes is a value sufficiently precise to provide important isotopic data of interest to astrobiologists. The precision presently attainable in gases is sufficient to permit our instrument to be used in the measurement of isotopic ratios of interest to astrobiologists as well as geologists and planetary scientists. A small stable isotope laser spectrometer with a 10 cm path gas cell was designed and constructed. The cell was integrated with a liquid nitrogen cooled tunable diode laser and indium antimonide detector for evaluation. Using the small gas cell, preliminary measurements of 13C/12C in CO2 were made employing single-beam sequential acquisitions of the required spectral data. The results indicate an accuracy of 0.1% which is sufficiently high to make meaningful measurements of martian samples. In addition, improvements in the spectrometer gas handling system have been made to markedly reduce C-13/C-12 isotopic fractionation during sample gas cell loading which we expect will lead to further improvements in precision and accuracy. An important part of making isotopic ratio measurements in solid samples using diode lasers is the conversion of the elements of interest to molecules that have absorption spectra in the mid-ir spectral range accessible by tunable diode lasers. In this project we have investigated the necessary sample preparation procedures to extract carbon, an element of astrobiological importance, from model soil compounds and to convert it to CO2, a molecule with appropriate optical absorption characteristics for reliable laser spectrometer isotopic ratio measurements of 13C/12C. We have considered calcium carbonate as a model for a component of the martian regolith, and we have formulated a simple heating protocol for extracting carbon in the form of CO2.

Becker, J. F.↗

Primary track recovery in high-definition gas time projection chambers

Abstract We develop and validate a new algorithm called primary track recovery () that effectively deconvolves known physics and detector effects from nuclear recoil tracks in gas time projection chambers (TPCs) with high-resolution readout. This gives access to the primary track charge, length, and vector direction (helping to resolve the “head-tail” ambiguity). Additionally, provides a measurement of the transverse and longitudinal diffusion widths, which can be used to determine the absolute position of tracks in the drift direction for detector fiducialization. Using simulated helium recoils in an atmospheric pressure TPC with a 70:30 mixture of $$\hbox {He:CO}_2$$ He:CO 2 we compare the performance of to traditional methods for all key track variables. We find that the algorithm reduces reconstruction errors, including those caused by charge integration, for tracks with mean length-to-width ratios 1.4 and above, corresponding to recoil energies of 20 keV and above in the studied TPCs. We show that improves on existing methods for head-tail disambiguation, particularly for highly inclined tracks, and improves the determination of the absolute position of recoils on the drift axis via transverse diffusion. We find that can partially recover charge structure integrated out by the detector in the z direction, but that its determination of energy and length have worse resolution compared to existing methods. We use experimental data to qualitatively verify these findings and discuss implications for future directional detectors at the low-energy frontier.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

Correction of the baseline fluctuations in the GEM-based ALICE TPC

To operate the ALICE Time Projection Chamber in continuous mode during the Run 3 and Run 4 data-taking periods of the Large Hadron Collider, the multi-wire proportional chamber-based readout was replaced with gas-electron multipliers. As expected, the detector performance is affected by the so-called common-mode effect, which leads to significant baseline fluctuations. A detailed study of the pulse shape with the new readout has revealed that it is also affected by ion tails. Since reconstruction and data compression are performed fully online, these effects must be corrected at the hardware level in the FPGA-based common readout units. The characteristics of the common-mode effect and of the ion tail, as well as the algorithms developed for their online correction, are described in this paper. The common-mode dependencies are studied using machine-learning techniques. Toy Monte Carlo simulations are performed to illustrate the importance of online corrections and to investigate the performance of the developed algorithms.

47 OTHER INSTRUMENTATION↗

Source characterization of a detector for heavy and superheavy nuclei

A new focal plane detector system for the Berkeley Gas-filled Separator (BGS) was designed, constructed, and tested offline with various α-decay and conversion-electron sources. The SuperHeavy RECoils (SHREC) detector comprises sets of double-sided silicon strip detectors arranged in an open-faced cuboid geometry. Alongside the detector upgrade new digital data acquisition electronics have been commissioned offline. This setup aims to detect separated recoiling heavy and superheavy nuclei as well as their correlated radioactive decay paths with improved energy resolution and overall sensitivity.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

Cosmic ray experimental observations

The current experimental situation in cosmic ray studies is discussed, with special emphasis on the development of new detector systems. Topics covered are the techniques for particle identification, energy measurements, gas Cerenkov counters, magnet spectrometers, ionization spectrometers, track detectors, nuclear emulsions, multiparameter analysis using arrays of detectors, the Goddard ionization spectrometer, charge spectra, relative abundances, isotope composition, antinuclei in cosmic rays, electrons, the measurement of cosmic ray arrival directions, and the prehistory of cosmic rays.

Balasubrahmanyan, V. K.↗

Detectors for high energy cosmic rays on Spacelab

Two instruments designed to determine the spectra of the individual cosmic-ray components at very high energies are described. One of these (CRNE) uses a combination of gas Cerenkov counters and transition radiation detectors for the cosmic-ray nuclei lithium to nickel; the other (TRIC) is optimized for the light cosmic rays (electrons, protons, helium) and uses a transition-radiation/ionization-calorimeter combination. The CRNE instrument, constructed at the University of Chicago, was delivered to NASA for a first Shuttle flight on Spacelab-2 in summer 1985. Some of the technical and programmatic requirements encountered during the hardware construction and integration are discussed, and the expected scientific return and the prospects of using such instrumentation on the Space Station are considered.

Lheureux, J.↗

Zero-Gravity Vortex Vent and PVT Gaging System

Space Station and satellite reservicing will require the ability to vent gas on orbit from liquid supply or storage tanks and to gage liquid quantity under microgravity conditions. In zero gravity, (zero-g) the vortex vent is capable of venting gas from a tank of liquid containing gas randomly distributed as bubbles. The concept uses a spinning impeller to create centrifugal force inside a vortex tube within a tank. This creates a gas pocket and forces the liquid through a venturi and back into the tank. Gas is then vented from the gas pocket through a liquid detector and then out through an exhaust port. If the liquid detector senses liquid in the vent line, the fluid is directed to the low-pressure port on the venturi and is returned to the tank. The advantages of this system is that it has no rotating seals and is compatible with most corrosive and cryogenic fluids. A prototype was designed and built at the NASA Johnson Space Center and flown on the KC-135 zero-g aircraft. During these test flights, where microgravity conditions are obtained for up to 30 sec, the prototype demonstrated that less than 0.10 percent of the volume of fluid vented was liquid when the tank was half full of liquid. The pressure volume temperature (PVT) gaging system is used in conjunction with the vortex vent to calculate the amount of liquid remaining in a tank under microgravity conditions. The PVT gaging system is used in conjunction with the vortex vent to gage liquid quantity in zero or low gravity. The system consists of a gas compressor, accumulator, and temperature and pressure instrumentation. To measure the liquid in a tank a small amount of gas is vented from the tank to the compressor and compressed into the accumulator. Pressure and temperature in the tank and accumulator are measured before and after the gas transfer occurs. Knowing the total volume of the tank, the volume of the accumulator, the volume of the intermediate lines, and initial and final pressures and temperatures, the mass of the gas leaving the tank is equated to the mass of the gas entering the accumulator. The volume of liquid remaining in the tank is calculated using the ideal gas law.

Downey, M. G.↗

Anisotropic Flow in Fixed-Target 208 Pb + 20 Ne Collisions as a Probe of Quark-Gluon Plasma

The System for Measuring Overlap with Gas (SMOG2) at the LHCb detector enables the study of fixed-target ion-ion collisions at relativistic energies ($\sqrt{𝑠_{NN}}$ ∼ 100 GeV in the center of mass). Here, with input from ab initio calculations of the structure of 16 O and 20 Ne , we compute 3+1⁢D hydrodynamic predictions for the anisotropic flow of Pb+Ne and Pb+O collisions to be tested with upcoming LHCb data. This will allow the detailed study of quark-gluon plasma formation as well as experimental tests of the predicted nuclear shapes. Elliptic flow (𝑣 2 ) in Pb + Ne collisions is greatly enhanced compared to the Pb + O baseline due to the shape of 20 Ne , which is deformed in a bowling-pin geometry. Owing to the large 208 Pb radius, this effect is seen in a broad centrality range, a unique feature of this collision configuration. Larger elliptic flow further enhances the quadrangular flow (𝑣 4 ) of Pb + Ne collisions via nonlinear coupling, and impacts the sign of the kurtosis of the elliptic flow vector distribution (𝑐 2 ⁡{4}). Exploiting the shape of 20 Ne proves thus an ideal method to investigate the formation of quark-gluon plasma in fixed-target experiments at LHCb, and demonstrates the power of System for Measuring Overlap with Gas as a tool to image nuclear ground states.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗