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At least 1,189 records · Page 66
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

X-ray spectrometer and methods for use

A spectrometer includes a crystal analyzer having a radius of curvature that defines a Rowland circle, a sample stage configured to support a sample such that the sample is offset from the Rowland circle, an x-ray source configured to emit unfocused x-rays toward the sample stage, and a position-sensitive detector that is tangent to the Rowland circle. A method performed via a spectrometer includes emitting, via an x-ray source, unfocused x-rays toward a sample that is mounted on a sample stage such that the sample is offset from the Rowland Circle, thereby causing the sample to emit x-rays that impinge on the crystal analyzer or transmit a portion of the unfocused x-rays to impinge on the crystal analyzer; scattering, via the crystal analyzer, the x-rays that impinge on the crystal analyzer; and detecting the scattered x-rays via a position-sensitive detector that is tangent to the Rowland circle.

Seidler, Gerald Todd↗
DOE OSTI2021

Compact folded metasurface spectrometer

Compact optical devices such as spectrometers are realized with metasurfaces within a dielectric medium confined by reflective surfaces. The metasurfaces control the phase profiles of the reflected electromagnetic waves within the device. In a compact spectrometer, the metasurfaces within the device separate the electromagnetic waves in different wavelengths. The metasurfaces are designed according to their phase profile by varying the size of the array of scatterers.

Faraji-Dana, MohammadSadegh↗
DOE OSTI2013

Polarized SIDIS Experiments with SoLID Spectrometer at 12 GeV Jefferson Lab

The Jefferson Lab 12 GeV upgrade will provide unique opportunity to perform polarized semi-inclusive deep inelastic scattering (SIDIS) experiments with very high precision. The measured single and double spin asymmetries (SSA/DSA) in these reactions will provide an access to various transverse momentum dependent parton distribution functions (TMDs). In particular, the experimentally measured SSA on proton and neutron targets can help us in extracting the transversity and Sivers distribution functions of u and d-quarks. Similarly, the measured DSA are sensitive to the quark spin-orbit correlations, and provide access to the worm-gear function (g1T). In this talk, we will present our plans for performing these precision measurements in Hall-A using a large acceptance SoLID spectrometer and polarized proton and 3He targets with 11 GeV beam. The high luminosities from these targets and the large acceptance of the SoLID spectrometer will allow for a precise 4-dimensional (x,Q2,z,PT) mapping of SSA and DSA. The data will provide comprehensive information on the correlation between quark angular momentum and the nucleon's spin.

Allada, Kalyan↗
DOE OSTI2013

Quartz Detector for the SuperHMS Spectrometer at Hall-C Jefferson Lab

We have developed and constructed a quartz hodoscope to be part of the trigger system for the Super High Momentum Spectrometer (SHMS). The SHMS spectrometer will play a central role in carrying out the 12-GeVphysics program at Hall-C Jefferson Lab. The hodoscope consists of twenty one fused silica bars. Each bar is 125-cm long, 5.5-cm wide, and 2.5-cm thick. It is viewed by a UV-sensitive PMT on each end. The quartz hodoscope task is to provide a clean detection of charged particles, a high level of background suppression, and an accurate tracking efficiency determination. We present results of tests leading to the construction of the hodoscope, as well performance test results of the completed detectors such as detection efficiency and position resolution.

Ahmidouch, Abdellah↗
DOE OSTI2012

Hodoscope for spectrometer optics calibration in APEX dark matter search

The A' Experiment (APEX) to be conducted in Hall A of Jefferson Lab (JLab) is a high sensitivity search for a proposed dark matter A' boson. To improve sensitivity APEX will make use of a new High Resolution Spectrometer (HRS) calibration method using a scintillating fiber (SciFi) hodoscope. A prototype SciFi hodoscope is developed to evaluate and improve the characteristics of the hodoscope design. The use of an active detector to calibrate the HRS is expected to allow for direct spectrometer calibration at any momentum setting without the use of special beam energies and improve scattering angle resolution by approximately 30\%.

Goeckner-Wald, Neil↗
DOE OSTI2021

Improved Nondestructive Isotopic Analysis with Practical Microcalorimeter Gamma Spectrometers

Advances in both instrumentation and data analysis software are now enabling the first ultra-high-resolution microcalorimeter gamma spectrometers designed for implementation in nuclear facilities and analytical laboratories. With approximately ten times better energy resolution than high-purity germanium detectors, these instruments can overcome important uncertainty limits. Microcalorimeter gamma spectroscopy is intended to provide nondestructive isotopic analysis capabilities with sufficient precision and accuracy to reduce the need for sampling, chemical separations, and mass spectrometry to meet safeguards and security goals. Key milestones were the development of the SOFIA instrument (Spectrometer Optimized for Facility Integrated Applications) and the SAPPY software (Spectral Analysis Program in PYthon). SOFIA is a compact instrument that combines advances in large multiplexed transition-edge sensor arrays with optimized cryogenic performance to overcome many practical limitations of previous systems. With a 256-pixel multiplexed detector array capable of 5,000 counts per second, measurement time can be comparable to high-purity germanium detectors. SAPPY was developed to determine isotopic ratios in data from SOFIA and other microcalorimeter instruments with an approach similar to the widely-used FRAM software. SAPPY provides a flexible framework with rigorous uncertainty analysis for both microcalorimeter and high purity germanium (HPGe) data, allowing direct comparison. Here, we present current results from the SOFIA instrument, preliminary isotopic analysis using SAPPY, and describe how the technology is being used to explore uncertainty limits of nondestructive isotopic characterization, inform safeguards models, and extract improved nuclear data including gamma-ray branching ratios.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2023

Development of Advanced Radionuclide Gamma spectrOmeter-2 (ARGO-2) for Low-level Radionuclide Measurements

A low-level multidimensional gamma spectrometer was recently installed at Pacific Northwest National Laboratory, USA. The spectrometer utilizes a dual-detector design and advanced detection techniques, demonstrating superior detection efficiency/sensitivity. This work details integral components of the system, including the dual-detector design, its shielding, and cosmic veto panels for background reduction. Results from system’s operation in singles and coincidence mode are highlighted.

ARGO, Coincidence measurements, Multidimensional g↗
DOE OSTI2023

X-ray spectrometer and methods for use

A spectrometer includes a crystal analyzer having a radius of curvature that defines a Rowland circle, a sample stage configured to support a sample such that the sample is offset from the Rowland circle, x-ray source configured to emit unfocused x-rays toward the sample stage, and a position-sensitive detector that is tangent to the Rowland circle. A method performed via a spectrometer includes emitting, via an x-ray source, unfocused x-rays toward a sample that is mounted on a sample stage such that the sample is offset from the Rowland Circle, thereby causing the sample to emit x-rays that impinge on the crystal analyzer or transmit a portion of the unfocused x-rays to impinge on the crystal analyzer; scattering, via the crystal analyzer, the x-rays that impinge on the crystal analyzer; and detecting the scattered x-rays via a position-sensitive detector that is tangent to the Rowland circle.

Seidler, Gerald Todd↗
DOE OSTI2024

Precise Measurement of the Neutron Magnetic Form Factor Using Super-BigBite Spectrometer at Jefferson Lab

The GMn experiment (E12-09-019) was conducted at Jefferson Laboratory from late 2021 into early 2022. The goal was to make high-precision measurement of the neutron’s magnetic form factor (GMn) at multiple kinematic points, including Q2 = 3.5, 4.5, 6.5, 8.5, 10, 12, 13.5, 16, and 18 (GeV/c)2. Limited data exist for GMn in the region up to about Q2 = 10 (GeV/c)2, with existing data having large systematic uncertainty. In this experiment, the ratio method was employed to reduce systematic uncertainty by measuring the ratio of neutron and proton yields. The experiment took place at Jefferson Laboratory in Hall A, where the BigBite spectrometer was used to detect the scattered electrons, while the HCal in the SuperBigbite spectrometer was used to detect both neutrons and protons. The protons were deflected slightly upwards with the use of a large-aperture dipole magnet named BigBen, allowing for enhanced particle identification. Extraction of GMn requires taking the ratio of proton and neutron yields. Analysis efforts are still currently underway to refine corrections to the data, including detector efficiencies, radiative corrections, neutron and proton mass identification, and charge exchange.

Lashley-Colthirst, Nathaniel↗
DOE OSTI2012

Gamma-to-electron magnetic spectrometer (GEMS): An energy-resolved {gamma}-ray diagnostic for the National Ignition Facility

The gamma-to-electron magnetic spectrometer, having better than 5% energy resolution, is proposed to resolve {gamma}-rays in the range of E{sub o}{+-} 20% in single shot, where E{sub o} is the central energy and is tunable from 2 to 25 MeV. Gamma-rays from inertial confinement fusion implosions interact with a thin Compton converter (e.g., beryllium) located at approximately 300 cm from the target chamber center (TCC). Scattered electrons out of the Compton converter enter an electromagnet placed outside the NIF chamber (approximately 600 cm from TCC) where energy selection takes place. The electromagnet provides tunable E{sub o} over a broad range in a compact manner. Energy resolved electrons are measured by an array of quartz Cherenkov converters coupled to photomultipliers. Given 100 detectable electrons in the energy bins of interest, 3 Multiplication-Sign 10{sup 14} minimum deuterium/tritium (DT) neutrons will be required to measure the 4.44 MeV {sup 12}C {gamma}-rays assuming 200 mg/cm{sup 2} plastic ablator areal density and 3 Multiplication-Sign 10{sup 15} minimum DT neutrons to measure the 16.75 MeV DT {gamma}-ray line.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2012

Fully digital data acquisition system for the neutron time-of-flight spectrometer TOFOR at JET

A prototype of a fully digital data acquisition system based on 1 Gsps 12 bit digitizers for the TOFOR fusion neutron spectrometer at JET is assessed. The prototype system enables the use of geometry-based background discrimination techniques, which are modeled, evaluated, and compared to experimental data. The experimental results are in line with the models and show a significant improvement in signal-to-background ratio in measured time-of-flight spectrum compared to the existing data acquisition system.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2013

Combined inclusive diffractive cross sections measured with forward proton spectrometers at HERA

A combination is presented of the inclusive diffractive cross section measurements made by the H1 and ZEUS Collaborations at HERA. The analysis uses samples of diffractive deep inelastic scattering data where leading protons are detected by dedicated spectrometers. Correlations of systematic uncertainties are taken into account by the combination method, resulting in improved precision.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2014

Second generation fusion neutron time-of-flight spectrometer at optimized rate for fully digital data acquisition

The progress on high-rate event recording of data is taken as starting point to revisit the design of fusion neutron spectrometers based on the TOF (time-of-flight) technique. The study performed was aimed at how such instruments for optimized rate (TOFOR) can be further developed to enhance the plasma diagnostic capabilities based on measurement of the 2.5 MeV dd neutron emission from D plasmas, especially the weak spectral components that depend on discrimination of extraneous events. This paper describes a design (TOFOR II) adapted for use with digital wave form recording of all detector pulses providing information on both amplitude (pulse height) and timing. The results of simulations are presented and the performance enhancement is assessed in comparison to the present.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2014

Data acquisition system with pulse height capability for the TOFED time-of-flight neutron spectrometer

A new time-of-flight neutron spectrometer TOFED has been constructed for installation at Experimental Advanced Superconducting Tokamak. A data acquisition system combining measurements of flight time and energy from the interaction of neutrons with the TOFED scintillators has been developed. The data acquisition system can provide a digitizing resolution better than 1.5% (to be compared with the >10% resolution of the recoil particle energy in the plastic scintillators) and a time resolution <1 ns. At the same time, it is compatible with high count rate event recording, which is an essential feature to investigate phenomena occurring on time scales faster than the slowing down time (≈100 ms) of the beam ions in the plasma. Implications of these results on the TOFED capability to resolve fast ion signatures in the neutron spectrum from EAST plasmas are discussed.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2014

Velocity-space sensitivity of the time-of-flight neutron spectrometer at JET

The velocity-space sensitivities of fast-ion diagnostics are often described by so-called weight functions. Recently, we formulated weight functions showing the velocity-space sensitivity of the often dominant beam-target part of neutron energy spectra. These weight functions for neutron emission spectrometry (NES) are independent of the particular NES diagnostic. Here we apply these NES weight functions to the time-of-flight spectrometer TOFOR at JET. By taking the instrumental response function of TOFOR into account, we calculate time-of-flight NES weight functions that enable us to directly determine the velocity-space sensitivity of a given part of a measured time-of-flight spectrum from TOFOR.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2014

Deuterium density profile determination at JET using a neutron camera and a neutron spectrometer

In this work we estimate the fuel ion density profile in deuterium plasmas at JET, using the JET neutron camera, the neutron time-of-flight spectrometer TOFOR, and fusion reactivities modeled by the transport code TRANSP. The framework has been tested using synthetic data, which showed that the density profile could be reconstructed with an average accuracy of the order of 10 %. The method has also been applied to neutron measurements from a neutral beam heated JET discharge, which gave n{sub d}/n{sub e} ≈ 0.6 ± 0.3 in the plasma core and n{sub d}/n{sub e} ≈ 0.4 ± 0.3 towards the edge. Correction factors for detector efficiencies, neutron attenuation, and back-scattering are not yet included in the analysis; future work will aim at refining the estimated density.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2014

A radial collimator for a time-of-flight neutron spectrometer

We have engineered and installed a radial collimator for use in the scattered beam of a neutron time-of-flight spectrometer at a spallation neutron source. The radial collimator may be used with both thermal and epithermal neutrons, reducing the detected scattering intensity due to material outside of the sample region substantially. The collimator is located inside of the sample chamber of the instrument, which routinely cycles between atmospheric conditions and cryogenic vacuum. The oscillation and support mechanism of the collimator allow it to be removed from use without breaking vacuum. We describe here the design and characterization of this radial collimator.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗