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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.

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All sourcesNASA NTRSDOE OSTI
DOE OSTI2011

Absolute energy calibration of FD by an electron linear accelerator for Telescope Array

The primary energy of the ultra-high energy cosmic rays(UHECR) are measured with the number of fluorescence photons which are detected with fluorescence detectors(FD) in the Telescope Array experiment(TA). Howevery since there is large uncertinty as 19% in the measurement of the energy scale, the most important theme is improvement of the energy calibration. The electron light source(ELS) is a small electron linear accelerator for new energy calibration. The ELS is located 100 m far from the FD station, and injects electron beam which is accelerated to 40 MeV energy into the sky. We can calibrate the FD energy scale by detection the air shower directly which is generated by the electron beam. The ELS was developed in KEK Japan, and moved to the TA site in March 2009. We started the beam operation in September 2010, in consequence we detected the air shower which was generated by electron beam in the air. The output kinetic energy of the electron beam was 41.1 MeV, we adjusted the output charge from 40 to 140 pC/pulse. We expect that we can improve the uncertinty of the energy scale to about 10% with the ELS, futhermore ELS will be a very useful apparatus for R and D of future UHECR observation.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2011

An Event Reconstruction Method for the Telescope Array Fluorescence Detectors

We measure arrival directions, energies and mass composition of ultra-high energy cosmic rays with air fluorescence detector telescopes. The longitudinal profile of the cosmic ray induced extensive air shower cascade is imaged on focal plane of the telescope camera. Here, we show an event reconstruction method to obtain the primary information from data collected by the Telescope Array Fluorescence Detectors. In particular, we report on an ''Inverse Monte Carlo (IMC)'' method in which the reconstruction process searches for an optimum solution via repeated Monte Carlo simulations including characteristics of all detectors, atmospheric conditions, photon emission and scattering processes.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2011

The Focal Surface of the JEM-EUSO Instrument

The Extreme Universe Space Observatory on JEM/EF (JEM-EUSO) is a space mission to study extremely high-energy cosmic rays. The JEM-EUSO instrument is a wide-angle refractive telescope in the near-ultraviolet wavelength region which will be mounted to the International Space Station. Its goal is to measure time-resolved fluorescence images of extensive air showers in the atmosphere. In this paper we describe in detail the main features and technological aspects of the focal surface of the instrument. The JEM-EUSO focal surface is a spherically curved surface, with an area of about 4.5m{sup 2}. The focal surface detector is made of more than 5,000 multi-anode photomultipliers (MAPMTs). Current baseline is Hamamatsu R11265-03-M64. The approach to the focal surface detector is highly modular. Photo-Detector-Modules (PDM) are the basic units that drive the mechanical structure and data acquisition. Each PDM consists of 9 Elementary Cells (ECs). The EC, which is the basic unit of the MAPMT support structure and of the front-end electronics, contains 4 units of MAPMTs. In total, about 1,200 ECs or about 150 PDMs are arranged on the whole of the focal surface of JEM-EUSO.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2011

The JEM-EUSO optics system

The Extreme Universe Space Observatory onboard the Japanese Experiment Module is an international mission devoted to the detection of ultra high-energy cosmic particles with energies E>7x10{sup 19} eV. They are revealed through emission in the atmosphere of Cherenkov and fluorescence light in the near-UV region, by using an optical system with 60 deg. field of view and a 2.3 m entrance pupil. One of the challenges consists in developing an unusual combination of large and lightweight refractive optics: two double-sided curved Fresnel lenses and a central curved Fresnel+diffractive lens, whose maximum dimensions are 2.65 m. This paper describes the development of such a optical system and its performances of the latest configurations.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2011

Radioactivity and electron acceleration in supernova remnants

We argue that the decays of radioactive nuclei related to {sup 44}Ti and {sup 56}Ni ejected during supernova explosions can provide a vast pool of mildly relativistic positrons and electrons which are further accelerated to ultrarelativistic energies by reverse and forward shocks. This interesting link between two independent processes - the radioactivity and the particle acceleration - can be a clue for solution of the well known theoretical problem of electron injection in supernova remnants. In the case of the brightest radio source Cas A, we demonstrate that the radioactivity can supply adequate number of energetic electrons and positrons for interpretation of observational data provided that they are stochastically preaccelerated in the upstream regions of the forward and reverse shocks.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Overall View of the JEM-EUSO Instruments

JEM-EUSO mission with a large and wide-angle telescope mounted on ISS has been planned to open up 'particle astronomy' through the investigation of extreme-energy cosmic rays by detecting fluorescent and Cherenkov photons by air showers developed in the earth's atmosphere. The JEM-EUSO telescope consists of optical Fresnel lenses with a diameter of about 2.5 m, 300 k channels of MAPMT, frontend readout electronics, trigger electronics, and system electronics. An infrared camera and a LIDAR system will be used to monitor the earth's atmosphere.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
NASA NTRS1989

Space Station - Infrastructure for radiation measurements in low earth orbit

The general configuration, development schedule, and capabilities of the NASA International Space Station are reviewed, with an emphasis on the possibilities for long-term measurements of high-energy cosmic and secondary radiation from the main Station spacecraft, coorbiting or polar-orbit platforms, or Station-supported GEO satellites. Also outlined are the organizational structure and the application procedures to be followed by potential users of the Station facilities. Diagrams and drawings are provided.

Meredith, B. D.↗
NASA NTRS1966

Production of low-energy cosmic-ray electrons.

Production of low energy cosmic ray electrons, investigating energy inputs to injected secondary electrons by possible low magnitude solar electric field and possible galactic Fermi acceleration

COSMIC RADIATION↗
DOE OSTI2012

SCALER MODE OF THE AUGER OBSERVATORY AND SUNSPOTS

Recent data from the Auger Observatory on low-energy secondary cosmic ray particles are analyzed to study temporal correlations together with data on the daily sunspot numbers and neutron monitor data. Standard spectral analysis demonstrates that the available data show 1/f {sup {beta}} fluctuations with {beta} Almost-Equal-To 1 in the low-frequency range. All data behave like Brownian fluctuations in the high-frequency range. The existence of long-range correlations in the data was confirmed by detrended fluctuation analysis. The real data confirmed the correlation between the scaling exponent of the detrended analysis and the exponent of the spectral analysis.

79 ASTRONOMY AND ASTROPHYSICS↗
NASA NTRS2012

Archway for Radiation and Micrometeorite Occurrence Resistance

The environmental conditions of the Moon require mitigation if a long-term human presence is to be achieved for extended periods of time. Radiation, micrometeoroid impacts, high-velocity debris, and thermal cycling represent threats to crew, equipment, and facilities. For decades, local regolith has been suggested as a candidate material to use in the construction of protective barriers. A thickness of roughly 3m is sufficient protection from both direct and secondary radiation from cosmic rays and solar protons; this thickness is sufficient to reduce radiation exposure even during solar flares. NASA has previously identified a need for innovations that will support lunar habitats using lightweight structures because the reduction of structural mass translates directly into additional up and down mass capability that would facilitate additional logistics capacity and increased science return for all mission phases. The development of non-pressurized primary structures that have synergy with the development of pressurized structures is also of interest. The use of indigenous or in situ materials is also a well-known and active area of research that could drastically improve the practicality of human exploration beyond low-Earth orbit. The Archway for Radiation and Micrometeorite Occurrence Resistance (ARMOR) concept is a new, multifunctional structure that acts as radiation shielding and micrometeorite impact shielding for long-duration lunar surface protection of humans and equipment. ARMOR uses a combination of native regolith and a deployed membrane jacket to yield a multifunctional structure. ARMOR is a robust and modular system that can be autonomously assembled on-site prior to the first human surface arrival. The system provides protection by holding a sufficiently thick (3 m) archshaped shell of local regolith around a central cavity. The regolith is held in shape by an arch-shaped jacket made of strong but deployable material. No regolith processing is required. During the regolith filling process, an inflatable structure under the arch supports the mass of the regolith, but once regolith filling is complete the catenary arch formed by the regolith and the jacket becomes self-supporting and the inflatable can be deflated and removed. When complete, habitat modules and equipment can be moved into the protected cavity under the arch. ARMOR is a nearterm system that would provide a reliable and robust lightweight structure technology to support large lunar habitats, drastically lower launch mass, and improve efficient volume use, reducing launch costs.

Giersch, Louis R.↗
NASA NTRS2012

Radiation Shielding Materials Containing Hydrogen, Boron, and Nitrogen: Systematic Computational and Experimental Study

The key objectives of this study are to investigate, both computationally and experimentally, which forms, compositions, and layerings of hydrogen, boron, and nitrogen containing materials will offer the greatest shielding in the most structurally robust combination against galactic cosmic radiation (GCR), secondary neutrons, and solar energetic particles (SEP). The objectives and expected significance of this research are to develop a space radiation shielding materials system that has high efficacy for shielding radiation and that also has high strength for load bearing primary structures. Such a materials system does not yet exist. The boron nitride nanotube (BNNT) can theoretically be processed into structural BNNT and used for load bearing structures. Furthermore, the BNNT can be incorporated into high hydrogen polymers and the combination used as matrix reinforcement for structural composites. BNNT's molecular structure is attractive for hydrogen storage and hydrogenation. There are two methods or techniques for introducing hydrogen into BNNT: (1) hydrogen storage in BNNT, and (2) hydrogenation of BNNT (hydrogenated BNNT). In the hydrogen storage method, nanotubes are favored to store hydrogen over particles and sheets because they have much larger surface areas and higher hydrogen binding energy. The carbon nanotube (CNT) and BNNT have been studied as potentially outstanding hydrogen storage materials since 1997. Our study of hydrogen storage in BNNT - as a function of temperature, pressure, and hydrogen gas concentration - will be performed with a hydrogen storage chamber equipped with a hydrogen generator. The second method of introducing hydrogen into BNNT is hydrogenation of BNNT, where hydrogen is covalently bonded onto boron, nitrogen, or both. Hydrogenation of BN and BNNT has been studied theoretically. Hyper-hydrogenated BNNT has been theoretically predicted with hydrogen coverage up to 100% of the individual atoms. This is a higher hydrogen content than possible with hydrogen storage; however, a systematic experimental hydrogenation study has not been reported. A combination of the two approaches may be explored to provide yet higher hydrogen content. The hydrogen containing BNNT produced in our study will be characterized for hydrogen content and thermal stability in simulated space service environments. These new materials systems will be tested for their radiation shielding effectiveness against high energy protons and high energy heavy ions at the HIMAC facility in Japan, or a comparable facility. These high energy particles simulate exposure to SEP and GCR environments. They will also be tested in the LaRC Neutron Exposure Laboratory for their neutron shielding effectiveness, an attribute that determines their capability to shield against the secondary neutrons found inside structures and on lunar and planetary surfaces. The potential significance is to produce a radiation protection enabling technology for future exploration missions. Crew on deep space human exploration missions greater than approximately 90 days cannot remain below current crew Permissible Exposure Limits without shielding and/or biological countermeasures. The intent of this research is to bring the Agency closer to extending space missions beyond the 90-day limit, with 1 year as a long-term goal. We are advocating a systems solution with a structural materials component. Our intent is to develop the best materials system for that materials component. In this Phase I study, we have shown, computationally, that hydrogen containing BNNT is effective for shielding against GCR, SEP, and neutrons over a wide range of energies. This is why we are focusing on hydrogen containing BNNT as an innovative advanced concept. In our future work, we plan to demonstrate, experimentally, that hydrogen, boron, and nitrogen based materials can provide mechanically strong, thermally stable, structural materials with effective radiation shielding against GCR, SEP, and neutrons.

Radiation↗
NASA NTRS1972

A study of radiation environment in space and its biological effects

Biological effects on man in space resulting from galactic and solar cosmic radiation are discussed. Importance of secondary ions which contribute to galactic cosmic radiation hazards is analyzed. Mathematical model to show rate of production of secondary ions of given atomic number at various points in absorber is presented.

Curtis, S. B.↗
NASA NTRS1984

An overview of medical-biological radiation hazards in earth orbits

The radiation exposure of crew members on space missions in LEO and GEO is evaluated in a general review. The radiation environment is characterized, taking the trapped radiation belts, solar flares, Galactic and solar cosmic rays, and secondary radiation into account and emphasizing the increased dosages produced by transient phenomena such as solar flares. The biological effects of space radiation in the individual cells, on the body as a whole, and on critical organs are summarized, and the exposure limits and shielding specifications (for spacecraft and for EVA suits) currently used by US mission planners are reviewed. For GEO, 4-g/sq cm Al-equivalent shielding is considered adequate under normal conditions, making EVA in this volatile environment questionable; for anomalously large solar flares, emergency shelter within 10-g/sq cm walls or the capability to retreat to a lower orbit is necessary.

Stauber, M. C.↗
NASA NTRS1985

The secondary radiation under Saturn's A-B-C rings produced by cosmic ray interactions

On the basis of a study of spacecraft data of Saturn, Chenette et al. (1980) concluded that highly relativistic galactic cosmic ray nuclei with magnetic rigidities greater than the Stoermer rigidity cutoff in the plane of Saturn's A-B-C rings along the Pioneer 11 trajectory produced a secondary population of charged particles. The existence of this secondary particle population was confirmed by Randall (1982). Cooper and Simpson (1980) further developed this concept of secondary production of nucleons by cosmic ray nuclei to estimate the yield of secondary neutrons which might, through decay, populate the radiation belt with low-energy electrons and protons. Cooper (1983) reported quantitative Monte Carlo calculations of neutron production in the rings and their decay in the magnetosphere. The present investigation is concerned with a confirmation of the earlier work, and an extension of the studies on the basis of improved spectra for the proton and electron components.

Cooper, J. F.↗
NASA NTRS2023

Mitigating Space Radiation Using Magnesium(-Lithium) and Boron Carbide Composites

The health effects of galactic cosmic radiation are a serious impediment to crewed exploration of the solar system. OLTARIS, an interface for the 3DHZETRN deterministic radiation transport code, was used to assess the response of aerospace materials to this constant radiation exposure. Traditional aerospace structural materials like aluminum can, after a certain mass, increase the health effects of such radiation. However, materials with lower atomic mass may mitigate this build-up in secondary radiation with increasing areal density. As such, lower atomic mass structural alloys of magnesium and magnesium–lithium are promising candidates. These alloys may reduce the mass of structures when substituted for aluminum alloys. Reinforcement with boron carbide could further reduce atomic mass while also improving the mechanical properties of such lightweight alloys. This study found that the lower atomic mass of these materials increased nuclear fragmentation upon cosmic radiation interactions, leading to a softening of the secondary (neutron) radiation spectra. This softened spectra reduced the effective dose equivalent, a measure of health effects, for magnesium(-lithium) alloys and their boron carbide-reinforced composites when compared to aluminum.

Galactic cosmic radiation↗
NASA NTRS2010

NASA Self-Assessment of Space Radiation Research

Space exploration involves unavoidable exposures to high-energy galactic cosmic rays whose penetration power and associated secondary radiation makes radiation shielding ineffective and cost prohibitive. NASA recognizing the possible health dangers from cosmic rays notified the U.S. Congress as early as 1959 of the need for a dedicated heavy ion accelerator to study the largely unknown biological effects of galactic cosmic rays on astronauts. Information and scientific tools to study radiation health effects expanded over the new decades as NASA exploration programs to the moon and preparations for Mars exploration were carried out. In the 1970 s through the early 1990 s a more than 3-fold increase over earlier estimates of fatal cancer risks from gamma-rays, and new knowledge of the biological dangers of high LET radiation were obtained. Other research has increased concern for degenerative risks to the central nervous system and other tissues at lower doses compared to earlier estimates. In 1996 a review by the National Academy of Sciences Space Science Board re-iterated the need for a dedicated ground-based accelerator facility capable of providing up to 2000 research hours per year to reduce uncertainties in risks projections and develop effective mitigation measures. In 1998 NASA appropriated funds for construction of a dedicated research facility and the NASA Space Radiation Laboratory (NSRL) opened for research in October of 2003. This year marks the 8th year of NSRL research were about 1000 research hours per year have been utilized. In anticipation of the approaching ten year milestone, funded investigators and selected others are invited to participate in a critical self-assessment of NSRL research progress towards NASA s goals in space radiation research. A Blue and Red Team Assessment format has been integrated into meeting posters and special plenary sessions to allow for a critical debate on the progress of the research and major gaps areas. Blue teams will highlight progress and important new knowledge gained. Red teams will challenge the Blue teams on proposed highlights and point to Gaps not considered. We will review the current space radiation Risks and Gaps under investigation at NASA, critical data sets and research highlights anticipated, and possible goals for future research at NSRL.

Cucinotta, Francis A.↗
NASA NTRS1987

Measurements of background gamma radiation on Spacelab 2

A nuclear radiation monitor (NRM) which was flown as part of the verification instrumentation on the Spacelab 2 mission (July 29 - August 6, 1985) recorded spectra every 20 seconds and counting rates in coarse energy bands on finer time scales. The gamma radiation environment on Spacelab is characterized by cosmic-ray and trapped proton secondary radiation in the Spacelab/Shuttle, earth albedo radiation, and delayed induced radioactivity in the detector and surrounding materials. It is found that passages through South Atlantic Anomaly protons produce a well-defined background enhancement.

Fishman, G. J.↗