Search NASA⌕ Search

SEARCH · Search NASA

Results for “Recoil protons”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 55 records · Page 3
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

The JLab Eta Factory (JEF) experiment

The new experiment, JLab Eta Factory (JEF), in the experimental Hall D at Jefferson Lab will extend the physics potential of the GlueX detector beyond the main spectroscopy program and perform precision measurements of various ?(?)decays with emphasis on rare neutral modes. The physics program of the experiment spans from precision tests of low-energy QCD to search of gauge bosons in the mass range below 1 GeV coupling the SM sector to the dark sector. Photoproduction of highly boosted ?(?)mesons using a tagged photon beam, good detection of recoil proton and multi-photon final states will allow to suppress background and collect high-statistics data sample of ?mesons. All these provide many advantages over other ?(?)experiments. The JEF experiment requires to upgrade the inner part of the forward lead glass calorimeter of the GlueX detector with high-granularity, high-resolution lead tungstate PbWO4 scintillating crystals. The calorimeter insert is currently under construction at Jeffeson Lab. The detector will be ready to take data in 2024. An overview of the JEF project will be presented.

Somov, Alexander↗
NASA NTRS1972

An application of interactive graphics to neutron spectrometry

The use of interactive graphics is presented as an attractive method for performing multi-parameter data analysis of proton recoil distributions to determine neutron spectra. Interactive graphics allows the user to view results on-line as the program is running and to maintain maximum control over the path along which the calculation will proceed. Other advantages include less time to obtain results and freedom from handling paper tapes and IBM cards.

Binney, S. E.↗
NASA NTRS1972

Comparison of neutron spectra measured with three sizes of organic liquid scintillators using differentiation analysis

Proton recoil distributions were obtained by using organic liquid scintillators of different size. The measured distributions are converted to neutron spectra by differentiation analysis for comparison to the unfolded spectra of the largest scintillator. The approximations involved in the differentiation analysis are indicated to have small effects on the precision of neutron spectra measured with the smaller scintillators but introduce significant error for the largest scintillator. In the case of the smallest cylindrical scintillator, nominally 1.2 by 1.3 cm, the efficiency is shown to be insensitive to multiple scattering and to the angular distribution to the incident flux. These characteristics of the smaller scintillator make possible its use to measure scalar flux spectra within media high efficiency is not required.

Shook, D. F.↗
NASA NTRS1973

Energy spectrum and flux of 3- to 20-Mev neutrons and 1- to 10-Mev gamma rays in the atmosphere

An experiment is described which was designed to measure the neutron and gamma ray energy spectrums and fluxes in the energy intervals 3 to 20 MeV and 1 to 10 MeV, respectively. In addition, from the 3 to 20-MeV proton recoil spectrums it is possible to infer the shape of the neutron energy spectrum from 20 to 50 MeV. The detecting system utilized a separate charged particle rejection scheme and a two-parameter display system for the output from the pulse shape discrimination which separated gamma rays from neutrons (n). Two long-duration flights were made with this detector in 1970 at Palestine, Tex. (P sub c = 4.6 Gv) and at Ft. Churchill, Canada (P sub c = 0.3 Gv).

Klumpar, D. M.↗
NASA NTRS1978

Personnel neutron monitoring in space

A brief review is presented of available information on the galactic neutron spectrum. An examination is made of the difficulties encountered in the determination of the dose equivalent of neutron recoil protons in the presence of a substantially larger background of trapped and star-produced protons as well as other ionizing particles in space.

Schaefer, H. J.↗
NASA NTRS1984

Optical and interfacial electronic properties of diamond-like carbon films

Hard, semitransparent carbon films were prepared on oriented polished crystal wafers of silicon, indium phosphide and gallium arsenide, as well as on KBr and quartz. Properties of the films were determined using IR and visible absorption spectrocopy, ellipsometry, conductance-capacitance spectroscopy and alpha particle-proton recoil spectroscopy. Preparation techniques include RF plasma decomposition of methane (and other hydrocarbons), ion beam sputtering, and dual-ion-beam sputter deposition. Optical energy band gaps as large as 2.7 eV and extinction coefficients lower than 0.1 at long wavelengths are found. Electronic state densities at the interface with silicon as low as 10 to the 10th states/eV sq cm per were found.

Woollam, J. A.↗
NASA NTRS1992

Synthesis and characterization of fine grain diamond films

A fine grain diamond film has been developed by microwave plasma assisted chemical vapor deposition. Various analytical techniques, including Rutherford backscattering, proton recoil analysis, Raman spectroscopy, and X-ray diffraction, were utilized to characterize the diamond films. The grain size of the film was determined from bright and dark field electron micrographs, and found to be 200-1000 A. The films exhibited good optical transmission between 2.5 and 10 microns, with a calculated absorption coefficient of 490/cm. The friction coefficients of this film were found to be 0.035 and 0.030 at dry nitrogen and humid air environments, respectively, and the films had low wear rates.

Wu, Richard L. C.↗
NASA NTRS1994

Friction and Wear Properties of As-deposited and Carbon Ion-implanted Diamond Films

Recent work on the friction and wear properties of as-deposited and carbon ion-implanted diamond films was reviewed. Diamond films were produced by the microwave plasma chemical vapor deposition (CVD) technique. Diamond films with various grain sizes and surface roughnesses were implanted with carbon ions at 60 ke V ion energy, resulting in a dose of 1.2310(exp 17) carbon ions/cm(exp 2). Various analytical techniques, including Raman spectroscopy, proton recoil analysis, Rutherford backscattering, transmission and scanning electron microscopy, x-ray photoelectron spectroscopy, and x-ray diffraction, were utilized to characterize the diamond films. Sliding friction experiments were conducted with a polished natural diamond pin in contact with diamond films in the three environments: humid air (40 percent relative humidity), dry nitrogen (less than 1 percent relative humidity), and ultrahigh vacuum (10(exp -7) Pa). The CVD diamond films indeed have friction and were properties similar to those of natural diamond in the three environments. The as-deposited, fine-grain diamond films can be effectively used as self-lubricating, wear-resistant coatings that have low coefficients of friction (0.02 to 0.04) and low wear rates (10(exp -7) to 10(exp -8)mm(exp 3)/N-m) in both humid air and dry nitrogen. However, they have high coefficients of friction (1.5 to 1.7) and a high wear rate (10(exp -4)mm(exp 3/N-m) in ultrahigh vacuum. The carbon ion implanation produced a thin surficial layer (less than 0.1 micron thick) of amorphous, nondiamond carbon on the diamond films. In humid air and dry nitrogen, the ion-implanted, fine- and coarse-grain diamond films have a low coefficient of friction (around 0.1) and a low wear rate (10(exp -7)mm(exp 3/N-m). Even in ultrahigh vacuum, the presence of the nondiamond carbon layer reduced the coefficient of friction of fine-grain diamond films to 0.1 or lower and the wear rate to 10(exp -6)mm(exp 3)/N-m. Thus, the carbon ion-implanted, fine-grain diamond films can be effectively used as wear-resistant, self-lubricating coatings not only in air and dry nitrogen, but also in ultrahigh vacuum. The wear mechanism of diamond films is that of small fragments chipping off the surface. The size of wear particles is related to the extent of wear rates.

Miyoshi, Kazuhisa↗
NASA NTRS1995

A study of the radiation environment on board the space shuttle flight STS-57

A joint NASA-Russian study of the radiation environment inside a SPACEHAB 2 locker on space shuttle flight STS-57 was conducted. The shuttle flew in a nearly circular orbit of 28.5 deg inclination and 462 km altitude. The locker carried a charged particle spectrometer, a tissue equivalent proportional counter (TEPC), and two area passive detectors consisting of combined NASA plastic nuclear track detectors (PNTD's) and thermoluminescent detectors (TLD's), and Russian nuclear emulsions, PNTD's, and TLD's. All the detector systems were shielded by the same shuttle mass distribution. This makes possible a direct comparison of the various dose measurement techniques. In addition, measurements of the neutron energy spectrum were made using the proton recoil technique. The results show good agreement between the integral LET spectrum of the combined galactic and trapped particles using the tissue equivalent proportional counter and track detectors between about 15 keV/micron and 200 keV/micron. The LET spectrum determined from nuclear emulsions was systematically lower by about 50%, possibly due to emulsion fading. The results show that the TEPC measured an absorbed dose 20% higher than TLD's, due primarily to an increased TEPC response to neutrons and a low sensitivity of TLD's to high LET particles under normal processing techniques. There is a significant flux of high energy neutrons that is currently not taken into consideration in dose equivalent calculations. The results of the analysis of the spectrometer data will be reported separately.

Badhwar, G. D.↗
NASA NTRS1996

Friction and Wear Properties of As-Deposited and Carbon Ion-Implanted Diamond Films

Recent work on the friction and wear properties of as-deposited and carbon ion-implanted diamond films was reviewed. Diamond films were produced by the microwave plasma chemical vapor deposition (CVD) technique. Diamond films with various grain sizes and surface roughnesses were implanted with carbon ions at 60 keV ion energy, resulting in a dose of 1.2 x 10(exp 17) carbon ions per cm(exp 2). Various analytical techniques, including Raman spectroscopy, proton recoil analysis, Rutherford backscattering, transmission and scanning electron microscopy, X-ray photoelectron spectroscopy, and X-ray diffraction, were utilized to characterize the diamond films. Sliding friction experiments were conducted with a polished natural diamond pin in contact with diamond films in the three environments: humid air (40% relative humidity), dry nitrogen (less than 1 percent relative humidity), and ultrahigh vacuum (10(exp -7) Pa). The CVD diamond films indeed have friction and wear properties similar to those of natural diamond in the three environments. The as-deposited, fine-grain diamond films can be effectively used as self-lubricating, wear-resistant coatings that have low coefficients of friction (0.02 to 0.04) and low wear rates (10(exp -7) to lO(exp -8) mm(exp 3) N(exp -1) m(exp -1)) in both humid air and dry nitrogen. However, they have high coefficients of friction (1.5 to 1.7) and a high wear rate (10(exp -4) mm(exp 7) N(exp -1) m(exp -1)) in ultrahigh vacuum. The carbon ion implantation produced a thin surficial layer (less than 0.1 micron thick) of amorphous, non-diamond carbon on the diamond films. In humid air and dry nitrogen, the ion-implanted, fine and coarse-grain diamond films have a low coefficient of friction (around 0.1) and a low wear rate (10(exp -7) mm(exp 3) N(exp -1) m(exp-1)). Even in ultrahigh vacuum, the presence of the non-diamond carbon layer reduced the coefficient of friction of fine-grain diamond films to 0.1 or lower and the wear rate to 10(exp -6) mm(exp 3) N(exp -1) m(exp -1). Thus, the carbon ion-implanted, fine-grain diamond films can be effectively used as wear-resistant, self-lubricating coatings not only in air and dry nitrogen, but also in ultrahigh vacuum.

Miyoshi, Kazuhisa↗
NASA NTRS2003

Neutron Measurements for Radiation Protection in Low Earth Orbit - History and Future

The neutron environment inside spacecraft has been of interest from a scientific and radiation protection perspective since early in the history of manned spaceflight. With 1:.1e exception of a few missions which carried plutonium-fueled radioisotope thermoelectric generators, all of the neutrons inside the spacecraft are secondary radiations resulting from interactions of high-energy charged particles with nuclei in the Earth's atmosphere, spacecraft structural materials, and the astronaut's own bodies. Although of great interest, definitive measurements of the spacecraft neutron field have been difficult due to the wide particle energy range and the limited available volume and power for traditional techniques involving Bonner spheres. A multitude of measurements, however, have been made of the neutron environment inside spacecraft. The majority of measurements were made using passive techniques including metal activation fo ils, fission foils, nuclear photoemulsions, plastic track detectors, and thermoluminescent detectors. Active measurements have utilized proton recoil spectrometers (stilbene), Bonner Spheres eRe proportional counter based), and LiI(Eu)phoswich scintillation detectors. For the International Space Station (ISS), only the plastic track! thermoluminescent detectors are used with any regularity. A monitoring program utilizing a set of active Bonner spheres was carried out in the ISS Lab module from March - December 200l. These measurements provide a very limited look at the crew neutron exposure, both in time coverage and neutron energy coverage. A review of the currently published data from past flights will be made and compared with the more recent results from the ISS. Future measurement efforts using currently available techniques and those in development will be also discussed.

Golightly, M. J.↗
NASA NTRS2011

What Threats to Human Health Does Space Radiation Pose in Orbit

The Space Shuttle program spanned more than the entire length of a solar cycle. Investigations aimed towards understanding the health risks of the astronauts from exposures to space radiation involved mostly physical measurements of the dose and the linear energy transfer (LET) spectrum. Measurement of the dose rate on the Shuttle provided invariable new data for different periods of the solar cycle, whereas measurement of the LET spectrum using the tissue equivalent proportional counter (TEPC) produced the most complete mapping of the radiation environment of the low Earth orbits (LEO). Exposures to the Shuttle astronauts were measured by the personal dosimeter worn by the crewmembers. Analysis of over 300 personal dosimeter readings indicated a dependence on the mission duration, the altitude and inclination of the orbit, and the solar cycle, with the crewmembers on the launch and repair of the Hubble telescope receiving the highest doses due to the altitude of the mission. Secondary neutrons inside the Shuttle were determined by recoil protons or with Bonner spheres, and may contribute significantly to the risks of the crewmembers. In addition, the skin dose and the doses received at different organs were compared using a human phantom onboard a Shuttle mission. A number of radiobiology investigations wer e also performed. The biological doses were determined on six astronauts/cosmonauts on long-duration Shuttle/Mir missions and on two crewmembers on a Hubble repair mission by analyzing the damages in the chromosomes of the crewmembers? white blood cells. Several experiments were also conducted to address the question of possible synergistic effects of spaceflight, microgravity in particular, on the repair of radiation-induced DNA damages. The experimental design included exposure of cells before launch, during flight, or after landing. These physical and biological studies were invaluable in predicting the health risks for astronauts on ISS and future exploration missions. Educational Objectives: A group of high school students flew color negative films on tw o Shuttle missions to detect the radiation environment in orbit. This and other experiments onboard of the Shuttle were aimed at educating the general public of the space program.

Wu, Honglu↗
NASA NTRS2019

The Solar Neutron TRACking (SONTRAC) Instrument for the Detection of Fast Neutrons

The detection of fast neutrons has important applications in several fields including solar, Geospace and planetary physics. Neutrons are challenging to detect and measurements of them typically suffer from high background rates. High-energy neutrons (>50 MeV) pose even more challenges, because the traditional double-scatter technique based on a time-of-flight (ToF) measurement is limited by short flight paths and small detector sizes characteristic of small satellite platforms. It is now possible to perform high-energy neutron measurements inside a large monolithic detector by imaging the recoil proton tracks, thus eliminating the need for a measure of the time-of-flight. The concept is based on a spectrometer assembled from numerous thin hydrogenous scintillating fibers that allow ionization track imaging. Fine grained readout is now possible with arrays of1-mm pitch silicon photomultipliers (SiPMs). The Solar Neutron TRACking (SONTRAC) instrument, equipped with scintillating fibers readout with SiPMs sensors, provides high-resolution, fine grained, imaging of fast (between 20-200 MeV) neutron scatters in a compact, low-power design ideal for small satellite(and aircraft) platforms. We discuss below applications of this technology and performance characteristics of the prototype SONTRAC instrument.

de Nolfo, Georgia A.↗
NASA NTRSDate not supplied

1D Projections Readout and Track Reconstruction for the SONTRAC Instrument

Neutron spectroscopy and imaging has improved considerably over the last decade with the advancement of modern scintillating materials and compact, low power readout devices. Though challenging to detect, fast (>0.5 MeV) neutrons are ubiquitous, contribute to the radiation exposure of astronauts and space hardware, and have been effectively used to examine physical processes both locally and within our heliosphere at large. The SOlar Neutron TRACking (SONTRAC) instrument is designed to measure neutrons between 20-200 MeV with good angular sensitivity. SONTRAC consists of orthogonally stacked scintillating fibers readout by silicon photomultipliers to detect and track the recoil protons from double scatter neutron events. Proton tracking provides high-resolution imaging of fast neutronsat energies where the bulk of solar and planetary neutrons resides. The SONTRAC readout system, algorithms for track reconstruction, and tracking performance are presented.

George Suarez↗
DOE OSTI2025

Exploring the Nucleon Structure via Deep Electroproduction Processes

Understanding the internal structure of the nucleon is a fundamental goal of modern physics, which aims at a comprehensive framework describing the internal dynamics of quarks and gluons. Among other structure functions, Generalized Parton Distributions (GPDs) offer a powerful framework for describing the nucleon dynamics by correlating the longitudinal momentum and the transverse position of its internal partons. Such a correlation provides a three-dimensional picture of the nucleon and enables access to fundamental properties, including the internal pressure distributions and the parton’s angular momentum contribution to the nucleon's total spin, thereby playing a central role in resolving the nucleon spin puzzle. At the Thomas Jefferson National Facility (JLab), polarized electron beam experiments allow for probing GPDs through the measurement of hard exclusive processes. Among the cleanest experimental channels, we find the electro-production of a real photon through the Deeply Virtual Compton Scattering (DVCS) mechanism. The first data-taking period of the CLAS12 program, taking place in 2018, allowed for unique DVCS Beam Spin Asymmetry (BSA) measurements in the phase space covered by a 10.6 GeV polarized electron beam impinging on an unpolarized liquid hydrogen target. Although detecting all final-state particles ensures exclusivity of the process, conservation laws indicate that it is not mandatory. I adopt an approach omitting the direct detection of the recoil proton, providing a simplified yet effective event selection strategy that boosts statistics and gives access to a larger phase space sensitive to the underlying GPD dynamics through BSA and cross section measurements. The Double DVCS (DDVCS) process promises a dedicated mapping of GPDs. Contributing to the electro-production of a lepton pair cross-section, the DDVCS reaction extends DVCS by allowing the final-state photon to be virtual, enriching the kinematic phase space and providing unique access to the internal correlations encoded by GPDs. A feasibility study is conducted to assess the potential of future DDVCS measurements at Jefferson Lab and the future Electron-Ion Collider (EIC). While Jefferson Lab will provide DDVCS measurements in the valence region through the SoLID$\mu$ and $\mu$CLAS12 experimental projects, in the long term, the EIC will provide complementary measurements in the sea region, both accessing unprecedented information about GPDs in a phase space region otherwise inaccessible. Taken together, these investigations demonstrate both the current capabilities and future opportunities for probing GPDs through exclusive processes. The experimental analysis of DVCS at CLAS12 provides precise measurements within an established framework, while the phenomenological study of DDVCS opens the door to richer and more comprehensive explorations with future detectors and facilities.

Alvarado, Juan [Université Paris-Saclay: Gif-sur-Y↗
DOE OSTI2025

Design and Construction of a High-Resolution Hodoscope for the GlueX Experiment with High-Statistics Analysis of the p0, ¿, and ¿1 Photoproduction Cross Sections from the RadPhi Experiment

Differential cross sections for forward-angle photoproduction of p0, ¿, and ¿ 1 pseudoscalar mesons were measured using data from the RadPhi experiment conducted in Hall B at Jef ferson Lab. RadPhi utilized a tagged bremsstrahlung photon beam incident on a stationary 9Be target, with a detector system configured to trigger on a recoil proton in coincidence with multiple neutral showers in the calorimeter. Events were reconstructed and subjected to kinematic constraints, with background suppressed via sideband subtraction guided by Monte Carlo modeling of background contributions. Cross sections were extracted over the photon energy range 4.4– 5.4 GeV and binned in invariant momentum transfer t, providing measurements from one of the first high-statistics experiments of forward ¿ and ¿1 pro duction from a nuclear target at these energies. Acceptance corrections were applied using a detailed GEANT-based simulation of the detector geometry and response. The resulting cross sections are consistent with 2020 CLAS results, when scaled by the number of protons in beryllium, and show broad agreement with other data and theoretical models. In parallel, a high-resolution photon tagger detector, the Tagger Microscope (TAGM), was designed, constructed, and commissioned for the GlueX experiment in Hall D at Jefferson Lab. The TAGM was developed to provide high-rate tagging capability in the coherent bremsstrahlung peak by detecting post-bremsstrahlung electrons across a one GeV range along the focal plane of the tagging spectrometer. The detector consists of a 5ˆ102 array of 2ˆ2 mm2 square BCF-20 plastic scintillating fibers thermally fused to BCF-98 light guide fibers optically coupled to silicon photomultipliers. These fibers are mounted in a precision machined framework enabling fine positional adjustments to maintain precise alignment with post-bremsstrahlung electron trajectories, while ensuring mechanical rigidity, thermal stability, optical isolation, minimal inactive area, and radiation shielding for electronics. The construction effort involved extensive testing of fiber quality, light transmission, thermal fusing, radiation hardness, and defect analysis using SEM and EDX techniques. Following its installation and commissioning, the TAGM became a critical component of the GlueX beamline, enabling high-rate tagging essential for studies of hybrid mesons and gluonic ex citations.

McIntyre, James [Univ. of Connecticut, Storrs, CT ↗