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At least 631 records · Page 35
All sourcesNASA NTRSDOE OSTI
NASA NTRS2008

Neutron Imaging Camera

We describe the Neutron Imaging Camera (NIC) being developed for DTRA applications by NASA/GSFC and NSWC/Carderock. The NIC is based on the Three-dimensional Track Imager (3-DTI) technology developed at GSFC for gamma-ray astrophysics applications. The 3-DTI, a large volume time-projection chamber, provides accurate, approximately 0.4 mm resolution. 3-D tracking of charged particles. The incident direction of fast neutrons, E(sub N) > 0.5 MeV. arc reconstructed from the momenta and energies of the proton and triton fragments resulting from 3He(n,p)3H interactions in the 3-DTI volume. We present angular and energy resolution performance of the NIC derived from accelerator tests.

Hunter, Stanley D.↗
NASA NTRS2009

GEMS

The prime scientific objectives of the Gravity and Extreme Magnetism SMEX, GEMS, are to determine the effects of the spin of black holes, the configurations of the magnetic fields of magnetars, and the structure of the supernova shocks which accelerate cosmic rays. In the cases of both stellar black holes and supermassive black holes, sensitivity to 1% polarization is needed to make diagnostic measurements of the net polarizations predicted for probable disk and corona models. GEMS can reach this goal for several Seyferts and quasars and measure the polarizations of representatives of a variety of other classes of X-ray sources, such as rotation-powered and accretion-powered pulsars. GEMS uses foil mirrors to maximize the collecting area achievable within the SMEX constraints. The polarimeters at the mirror foci are Time Projection Chambers which use the photoelectic effect to measure the polarization of the incident photon. We have built laboratory models with good efficiency and modulation in the 2-10 keV range. An attached small student experiment would add 0.5 keV sensitivity for bright soft sources. The instrument has a point spread function which allows measurement of structures in the brighter nearby supernova remnants. GEMS' Orbital Sciences spacecraft will rotate at a rate of 0.1 revolutions per minute during observations, so that systematic errors due to the detector can be detected and corrected. A program of 35 sources can be observed in 9 months. GEMS is designed for a two year lifetime which will allow a General Observer program that would more than double the number of sources measured. For subsets of black holes, neutron stars and supernova remnants, GEMS will measure the polarization of several sources, solving important questions while establishing the sensitivity required for future missions.

Swank, Jean↗
NASA NTRS2010

Development of a Telescope for Medium-Energy Gamma-Ray Astronomy

Since the launch of AGILE and FERMI, the scientific progress in high-energy (E(sub gamma) greater than approximately 200 MeV) gamma-ray science has been, and will continue to be dramatic. Both of these telescopes cover a broad energy range from approximately 20 MeV to greater than 10 GeV. However, neither instrument is optimized for observations below approximately 200 MeV where many astrophysical objects exhibit unique, transitory behavior, such as spectral breaks, bursts, and flares. Hence, while significant progress from current observations is expected, there will nonetheless remain a significant sensitivity gap in the medium-energy (approximately 0.1-200 MeV) regime; the lower end of this range remains largely unexplored whereas the upper end will allow comparison with FERMI data. Tapping into this unexplored regime requires significant improvements in sensitivity. A major emphasis of modern detector development, with the goal of providing significant improvements in sensitivity in the medium-energy regime, focuses on high-resolution electron tracking. The Three-Dimensional Track Imager (3-DTI) technology being developed at GSFC provides high resolution tracking of the electron-positron pair from gamma-ray interactions from 5 to 200 MeV. The 3-DTI consists of a time projection chamber (TPC) and 2-D cross-strip microwell detector (MWD). The low-density and homogeneous design of the 3-DTI, offers unprecedented sensitivity by providing angular resolution near the kinematic limit. Electron tracking also enables measurement of gamma-ray polarization, a new tool to study astrophysical phenomenon. We describe the design, fabrication, and performance of a 30x30x30 cubic centimeters 3-DTI detector prototype of a medium-energy gamma-ray telescope.

Hunter, Stanley D.↗
NASA NTRS2011

The Gravity and Extreme Magnetism Small Explorer (GEMS)

The Gravity and Extreme Magnetism Small Explorer (GEMS) was selected by NASA for flight in 2014 to make a sensitive search for X-ray polarization from a wide set of source classes, including stellar black holes, Seyfert galaxies and quasars, blazars, rotation and accretion-powered pulsars, magnetars, shell supernova remnants and pulsar wind nebulae. Among the primary scientific objectives are determining the effects of the spin of black holes and the geometry of supermassive black hole accretion, determining the configurations of the magnetic fields and the X-ray emission of magnetars, and determining the magnetic structure of the supernova shocks in which cosmic rays are accelerated. GEMS will observe 23 targets during a 16 month prime mission, in observations that will be able to reach predicted levels of polarization. The mission can be extended to provide a guest observer phase. The GEMS instrument has time projection chamber polarimeters with high 2-10 keV efficiency at the focus of thin foil mirrors. The 4.5 m focal length mirrors will be deployed on an extended boom. The spacecraft with the instrument is rotated with a period of about 10 minutes to enable measurement and correction of systematic errors. A small Bragg reflection soft X-ray experiment takes advantage of this rotation to obtain a measurement at 0.5 keV. The design of the GEMS instrument and the mission, the expected performance and the planned science program will be discussed.

Kallman, T. R.↗
NASA NTRS2011

X-Ray Polarimetry with GEMS

The polarization properties of cosmic X-ray sources are still largely unexplored. The Gravity and Extreme Magnetism SMEX (GEMS) will carry out the first sensitive X-ray polarization survey of a wide range of sources including; accreting compact objects (black holes and neutron stars), AGN, supernova remnants, magnetars and rotation-powered pulsars. GEMS employs grazing-incidence foil mirrors and novel time-projection chamber (TPC) polarimeters leveraging the photoelectric effect to achieve high polarization sensitivity in the 2 - 10 keV band. I will provide an update of the project status, illustrate the expected performance with several science examples, and provide a brief overview of the data analysis challenges

Strohmayer, Tod↗
NASA NTRS2011

The Advanced Energetic Pair Telescope (AdEPT}: A Future Medium-Energy Gamma-Ray Balloon (and Explorer?) Mission

Gamma-ray astrophysics probes the highest energy, exotic phenomena in astrophysics. In the medium-energy regime, 0.1-200 MeV, many astrophysical objects exhibit unique and transitory behavior such as the transition from electron dominated to hadron dominated processes, spectral breaks, bursts, and flares. Medium-energy gamma-ray imaging however, continues to be a major challenge particularly because of high background, low effective area, and low source intensities. The sensitivity and angular resolution required to address these challenges requires a leap in technology. The Advance Energetic Pair Telescope (AdEPT) being developed at GSFC is designed to image gamma rays above 5 MeV via pair production with angular resolution of 1-10 deg. In addition AdEPT will, for the first time, provide high polarization sensitivity in this energy range. This performance is achieved by reducing the effective area in favor of enhanced angular resolution through the use of a low-density gaseous conversion medium. AdEPT is based on the Three-Dimensional Track Imager (3-DTI) technology that combines a large volume Negative Ion Time Projection Chamber (NITPC) with 2-D Micro-Well Detector (MWD) readout. I will review the major science topics addressable with medium-energy gamma-rays and discuss the current status of the AdEPT technology, a proposed balloon instrument, and the design of a future satellite mission.

Hunter, Stanley D.↗
NASA NTRS2011

Data Analysis And Polarization Measurements With GEMS

The Gravity and Extreme Magnetism SMEX (GEMS) mission was selected by NASA for flight in 2014. GEMS will make the first sensitive survey of X-ray polarization across a wide range of source classes including black hole and neutron star binaries, AGN of different types, rotation and accretion-powered pulsars, magnetars, shell supernova remnants and pulsar wind nebulae. GEMS employs grazing-incidence foil mirrors and novel time-projection chamber (TPC) polarimeters leveraging the photoelectric effect. The GEMS detectors image the charge tracks of photoelectrons produced by 2 - 10 keV X-rays. The initial direction of the photoelectron is determined by the linear polarization of the photon. We present an overview of the data analysis challenges and methods for GEMS, including procedures for producing optimally filtered images of the charge tracks and estimating their initial directions. We illustrate our methods using laboratory measurements of polarized and unpolarized X-rays with flight-like detectors as well as from simulated tracks. We also present detailed simulations exploring the statistics of polarization measurements appropriate for GEMS, and make comparisons with previous work.

Stohmayer, Tod↗
NASA NTRS2011

Imaging X-Ray Polarimeter for Solar Flares (IXPS)

We describe the design of a balloon-borne Imaging X-ray Polarimeter for Solar flares (IX PS). This novel instrument, a Time Projection Chamber (TPC) for photoelectric polarimetry, will be capable of measuring polarization at the few percent level in the 20-50 keV energy range during an M- or X class flare, and will provide imaging information at the approx.10 arcsec level. The primary objective of such observations is to determine the directivity of nonthermal high-energy electrons producing solar hard X-rays, and hence to learn about the particle acceleration and energy release processes in solar flares. Secondary objectives include the separation of the thermal and nonthermal components of the flare X-ray emissions and the separation of photospheric albedo fluxes from direct emissions.

Hosack, Michael↗
NASA NTRS2012

Gravity and Extreme Magnetism SMEX

The Gravity and Extreme Magnetism SMEX mission will be the first mission to catalogue the X-ray polarisation of many astrophysical objects including black-holes and pulsars. This first of its kind mission is enabled by the novel use of a time projection chamber as an X-ray polarimeter. The detector has been developed over the last 5 years, with the current effort charged toward a demonstration of it's technical readiness to be at level 6 prior to the preliminary design review. This talk will describe the design GEMS polarimeter and the results to date from the engineering test unit.

Source record↗
NASA NTRS2012

Development of a Telescope for Medium-Energy Gamma-ray Astronomy

Since the launch of AGILE and FERMI, the scientific progress in high-energy (Eg greater than approximately 200 MeV) gamma-ray science has been, and will continue to be dramatic. Both of these telescopes cover a broad energy range from approximately 20 MeV to greater than 10 GeV. However, neither instrument is optimized for observations below approximately 200 MeV where many astrophysical objects exhibit unique, transitory behavior, such as spectral breaks, bursts, and flares. Hence, while significant progress from current observations is expected, there will nonetheless remain a significant sensitivity gap in the medium-energy (approximately 0.1-200 MeV) regime; the lower end of this range remains largely unexplored whereas the upper end will allow comparison with FERMI data. Tapping into this unexplored regime requires significant improvements in sensitivity. A major emphasis of modern detector development, with the goal of providing significant improvements in sensitivity in the medium-energy regime, focuses on high-resolution electron tracking. The Three-Dimensional Track Imager (3-DTI) technology being developed at GSFC provides high resolution tracking of the electron-positron pair from gamma-ray interactions from 5 to 200 MeV. The 3-DTI consists of a time projection chamber (TPC) and 2-D cross-strip microwell detector (MWD). The low-density and homogeneous design of the 3-DTI, offers unprecedented sensitivity by providing angular resolution near the kinematic limit. Electron tracking also enables measurement of gamma-ray polarization, a new tool to study astrophysical phenomenon. We describe the design, fabrication, and performance of a 30x30x30 cm3 3-DTI detector prototype of a medium-energy gamma-ray telescope.

Sunter, Stan↗
NASA NTRS2012

GEMS X-ray Polarimeter Performance Simulations

The Gravity and Extreme Magnetism Small explorer (GEMS) is an X-ray polarization telescope selected as a NASA small explorer satellite mission. The X-ray Polarimeter on GEMS uses a Time Projection Chamber gas proportional counter to measure the polarization of astrophysical X-rays in the 2-10 keV band by sensing the direction of the track of the primary photoelectron excited by the incident X-ray. We have simulated the expected sensitivity of the polarimeter to polarized X-rays. We use the simulation package Penelope to model the physics of the interaction of the initial photoelectron with the detector gas and to determine the distribution of charge deposited in the detector volume. We then model the charge diffusion in the detector,and produce simulated track images. Within the track reconstruction algorithm we apply cuts on the track shape and focus on the initial photoelectron direction in order to maximize the overall sensitivity of the instrument, using this technique we have predicted instrument modulation factors nu(sub 100) for 100% polarized X-rays ranging from 10% to over 60% across the 2-10 keV X-ray band. We also discuss the simulation program used to develop and model some of the algorithms used for triggering, and energy measurement of events in the polarimeter.

Baumgartner, Wayne H.↗
NASA NTRS2014

A Pair Production Telescope for Medium-Energy Gamma-Ray Polarimetry

We describe the science motivation and development of a pair production telescope for medium-energy (approximately 5-200 Mega electron Volts) gamma-ray polarimetry. Our instrument concept, the Advanced Energetic Pair Telescope (AdEPT), takes advantage of the Three-Dimensional Track Imager, a low-density gaseous time projection chamber, to achieve angular resolution within a factor of two of the pair production kinematics limit (approximately 0.6 deg at 70 Mega electron Volts), continuum sensitivity comparable with the Fermi-LAT front detector (is less than 3 x 10(exp -6) Mega electron Volts per square centimeter per second at 70 Mega electron Volts), and minimum detectable polarization less than 10% for a 10 milliCrab source in 10(exp 6) s.

Gamma rays↗
NASA NTRS2014

Properties of the Flight Model Gas Electron Multiplier for the GEMS Mission

We present the gain properties of the gas electron multiplier (GEM) foil in pure dimethyl ether (DME) at 190 Torr. The GEM is one of the micro pattern gas detectors and it is adopted as a key part of the X-ray polarimeter for the GEMS mission. The X-ray polarimeter is a time projection chamber operating in pure DME gas at 190 Torr. We describe experimental results of (1) the maximum gain the GEM can achieve without any discharges, (2) the linearity of the energy scale for the GEM operation, and (3) the two-dimensional gain variation of the active area. First, our experiment with 6.4 keV X-ray irradiation of the whole GEM area demonstrates that the maximum effective gain is 2 x 10(exp 4) with the applied voltage of 580 V. Second, the measured energy scale is linear among three energies of 4.5, 6.4, and 8.0 keV. Third, the two-dimensional gain mapping test derives the standard deviation of the gain variability of 7% across the active area.

gas electron multiplier (GEM)↗
NASA NTRS2016

Performance of the PRAXyS X-Ray Polarimeter

The performance of the Time Projection Chamber (TPC) polarimeter for the Polarimeter for Relativistic Astrophysical X-ray Sources (PRAXyS) Small Explorer was evaluated using polarized and unpolarized X-ray sources. The PRAXyS mission will enable exploration of the universe through X-ray polarimetry in the 2-10 keV energy band. We carried out performance tests of the polarimeter at the Brookhaven National Laboratory, National Synchrotron Light Source (BNL-NSLS) and at NASA's Goddard Space Flight Center. The polarimeter was tested with linearly polarized, monochromatic X-rays at 11 different energies between 2.5 and 8.0 keV. At maximum sensitivity, the measured modulation factors at 2.7, 4.5 and 8.0 keV are 27%, 43% and 59%, respectively and the measured angle of polarization is consistent with the expected value at all energies. Measurements with a broadband, unpolarized X-ray source placed a limit of less than 1% on false polarization in the PRAXyS polarimeter.

PRAXyS↗
NASA NTRS2016

The Polarimeter for Relativistic Astrophysical X-ray Sources

The Polarimeter for Relativistic Astrophysical X-ray Sources (PRAXyS) is one of three Small Explorer (SMEX) missions selected by NASA for Phase A study, with a launch date in 2020. The PRAXyS Observatory exploits grazing incidence X-ray mirrors and Time Projection Chamber Polarimeters capable of measuring the linear polarization of cosmic X-ray sources in the 2-10 keV band. PRAXyS combines well-characterized instruments with spacecraft rotation to ensure low systematic errors. The PRAXyS payload is developed at the Goddard Space Flight Center with the Johns Hopkins University Applied Physics Laboratory, University of Iowa, and RIKEN (JAXA) collaborating on the Polarimeter Assembly. The LEOStar-2 spacecraft bus is developed by Orbital ATK, which also supplies the extendable optical bench that enables the Observatory to be compatible with a Pegasus class launch vehicle. A nine month primary mission will provide sensitive observations of multiple black hole and neutron star sources, where theory predicts polarization is a strong diagnostic, as well as exploratory observations of other high energy sources. The primary mission data will be released to the community rapidly and a Guest Observer extended mission will be vigorously proposed.

Small Explorer↗
NASA NTRS2016

The X-Ray Polarimeter Instrument on Board the Polarimeter for Relativistic Astrophysical X-Ray Sources (PRAXyS) Mission

The Polarimeter for Relativistic Astrophysical X-ray Sources (PRAXyS) is one of three Small Explorer (SMEX) missions selected by NASA for Phase A study. The PRAXyS observatory carries an X-ray Polarimeter Instrument (XPI) capable of measuring the linear polarization from a variety of high energy sources, including black holes, neutron stars, and supernova remnants. The XPI is comprised of two identical mirror-Time Projection Chamber (TPC) polarimeter telescopes with a system effective area of 124 sq cm at 3 keV, capable of photon limited observations for sources as faint as 1 mCrab. The XPI is built with well-established technologies. This paper will describe the performance of the XPI flight mirror with the engineering test unit polarimeter

polarization↗
NASA NTRS2020

Development and Performance Verification of a TPC Polarimeter for High Energy X-rays

We present the first application of a time projection chamber polarimeter to measure high energy X-ray polarization above 10 keV. The polarimeter is designed based on the PRAXyS soft X-ray polarimeter. The sealed gas is changed to a gas mixture of 60% argon and 40% dimethyl ether at 1 atm to be sensitive to high energy X-rays. The polarimeter performance is verified with linearly polarized, monochromatic X-rays at a synchrotron radiation facility, KEK Photon Factory BL-14A. The measured modulation factors are 42.4±0.6%, 50.4±0.6%,and 55.0±0.6% at 12, 14, and 16 keV, respectively, and the measured polarization angles are consistent with the expected values at all energies.

Tomoshi Takeda↗
DOE OSTI2020

Studies of Single-Transverse Kinematic Variables for Neutrino Interactions on Argon

It is now well-known that a variety of theoretically-challenging nuclear effects play an important role in determining neutrino-nucleus interaction cross sections. Deficiencies in existing models of these effects represent a leading source of systematic uncertainty for neutrino oscillation experiments. In recent neutrino cross section measurements published by the T2K and MINERvA experiments, the study of kinematic observables called Single-Transverse (Kinematic) Variables (STVs) in the plane transverse to the neutrino beam have been demonstrated to provide a powerful tool on nuclear modeling uncertainties. In the near future, the SBN and DUNE experiments will both leverage the novel Liquid Argon Time Projection Chamber technology to pursue high-precision measurements of neutrino oscillations. As the interpretation of the results from these measurements will require a detailed understanding of neutrino-argon scattering cross sections and given the scarcity of available neutri no-argon data, a measurement of Single-Transverse Kinematic Variables distributions in neutrino-argon scattering is of high interest for the neutrino physics community. This thesis presents the first detailed comparison of model predictions for distributions of these observables obtained using four standard neutrino event simulation tools (GENIE, NuWro, GiBUU and NEUT). Results are shown for simulations of muon neutrinos from the Fermilab Booster Neutrino Beam interacting in the MicroBooNE LArTPC. Opportunities for discrimination between nuclear models with respect to future measurements is highlighted. Furthermore, first calculations of STVs from experimental argon data are shown. Data corresponding to 4.449x10^19 POT of exposure were collected using the MicroBooNE LArTPC in the Fermilab Booster Neutrino Beam.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗