532 research outputs found
Manned geosynchronous mission requirements and systems analysis study. Volume 1: Executive summary
The crew capsule of the MOTV was studied with emphasis on crew accommodations, crew capsule functional requirements, subsystem interface definition between crew module and propulsion module, and man rating requirements. Competing mission modes were studied covering a wide range of propulsion concepts. These included one stage, one and one half stage, and two stage concepts using either the standard STS or an augmented STS. Several deorbit concepts were considered, including all propulsive modes, direct re-entry, and aeromaneuvering skip in skip out in the upper reaches of Earth's atmosphere. A five year plan covering costs, schedules, and critical technology issues is discussed
Manned Orbital Transfer Vehicle (MOTV). Volume 3: Program requirements documents
The requirements for geosynchronous orbit capability using the manned orbit transfer vehicle (MOTV) are defined. The program requirements, the mission requirements, and the system and subsystem requirements for the MOTV are discussed. The mission requirements include a geosynchronous Earth orbit vehicle for the construction, servicing, repair and operation of communications, solar power, and Earth observation satellites
Manned Orbital Transfer Vehicle (MOTV). Volume 2: Mission handbook
The use of the manned orbit transfer vehicle (MOTV) for support of future space missions is defined. Some 20 generic missions are defined each representative of the types of missions expected to be flown in the future. These include the service and update of communications satellites, emergency repair of surveillance satellites, and passenger transport of a six man crew rotation/resupply service to a deep space command post. The propulsive and functional capabilities required of the MOTV to support a particular mission are described and data to enable the user to determine the number of STS flights needed to support the mission, mission peculiar equipment requirements, parametrics on mission phasing and requirements, ground and flight support requirements, recovery considerations, and IVA/EVA trade analysis are presented
Manned Orbital Transfer Vehicle (MOTV). Volume 4: Supporting analysis
Generic missions were defined to enable potential users to determine the parameters for suggested user projects. Mission modes were identified for providing operation, interfaces, performance, and cost data for studying payloads. Safety requirements for emergencies during various phases of the mission are considered with emphasis on radiation hazards
Manned Orbital Transfer Vehicle (MOTV). Volume 6: Five year program plan
The five year program plan for the manned orbit transfer vehicle (MOTV) is presented. The planning, schedules, cost estimates, and supporting data (objectives, constraints, assumptions, etc.) associated with the development of the MOTV are discussed. The plan, in addition to the above material, identifies the supporting research and technology required to resolve issues critical to MOTV development
Modeling Lepton-Nucleon Inelastic Scattering from High to Low Momentum Transfer
We present a model for inclusive charged lepton-nucleon and
(anti)neutrino-nucleon cross sections at momentum transfer squared, ,
. We quantify the impact of existing low-Q charged-lepton
deep-inelastic scattering (DIS) data on effects due to high-twist operators and
on the extraction of parton distribution functions (PDFs). No evidence is found
for twist-6 contributions to structure functions (SF), and for a twist-4 term
in the logitudinal SF at . We find that DIS data are consistent
with the NNLO QCD approximation with the target mass and phenomenological high
twist corrections. For , we extend extrapolation of the
operator product expansion, preserving the low- current-conservation
theorems. The procedure yields a good description of data down to . An updated set of PDFs with reduced uncertainty and applicable
down to small momentum transfers in the lepton-nucleon scattering is obtained.Comment: 10 pages, 6 figures, proceedings of the 5th International Workshop on
Neutrino-Nucleus Interactions in the Few-GeV Region (NuInt07), Batavia,
Illinois, 30 May - 3 Jun 200
Nuclear parton distribution functions and their uncertainties
We analyze experimental data of nuclear structure-function ratios
F_2^A/F_2^{A'} and Drell-Yan cross section ratios for obtaining optimum parton
distribution functions (PDFs) in nuclei. Then, uncertainties of the nuclear
PDFs are estimated by the Hessian method. Valence-quark distributions are
determined by the F_2 data at large x; however, the small-x part is not obvious
from the data. On the other hand, the antiquark distributions are determined
well at x~0.01 from the F_2 data and at x~0.1 by the Drell-Yan data; however,
the large-x behavior is not clear. Gluon distributions cannot be fixed by the
present data and they have large uncertainties in the whole x region.
Parametrization results are shown in comparison with the data. We provide a
useful code for calculating nuclear PDFs at given x and Q^2.Comment: 9 pages, REVTeX, 23 eps files, Phys. Rev. C in press. Nuclear PDF
library is available at http://hs.phys.saga-u.ac.jp/nuclp.htm
Nuclear Effects in Neutrino Structure Functions
We discuss calculation of nuclear corrections to the structure functions for
the deep-inelastic scattering of muon and (anti)neutrino. Our approach includes
a QCD description of the nucleon structure functions as well as the treatment
of Fermi motion and nuclear binding, off-shell correction to bound nucleon
structure functions, nuclear pion excess and nuclear shadowing. We emphasize
the dependence of nuclear effects on the type and C-parity of (anti)neutrino
structure functions. We also examine the interplay between different nuclear
effects in the Adler and the Gross-Llewellyn-Smith sum rules for nuclei.Comment: 8 pages, 2 figures, to appear in the proceedings of 5th International
Workshop on Neutrino-Nucleus Interactions in the Few-GeV Region (NuInt07),
Batavia, Illinois, 30 May - 3 Jun 200
Anomalous prompt photon production in hadronic collisions at low-
We investigate the discrepancy that exists at low- between
the next--to--leading order QCD calculations of prompt photon production and
the measured cross section. The central values of the measured cross section
are of order 100\% larger than QCD predictions in this region. It has been
suggested that the bremsstrahlung contribution may account for this
discrepancy. The quark fragmentation function has not been
measured and an exactly known asymptotic form is normally used in calculations.
We examine the effect of much larger fragmentation functions on the QCD
predictions. After illustrating the effect of the large fragmentation functions
in some detail for recent CDF data at =1.8~TeV, we perform a
fit to 8 prompt photon data sets ranging in CMS energy from 24~GeV to 1.8~TeV.
While a large fragmentation function normalization may prove to play an
important role in resolving the discrepancy, the present theoretical and
experimental uncertainties prevent any definite normalization value from being
determined.Comment: 14 pages, LBL-33122 and UCB-PTH-92/38. 13 figures available by email,
specify postscript or topdrawe
Inclusive particle production at HERA: Higher-order QCD corrections to the resolved quasi-real photon contribution
We calculate in next-to-leading order inclusive cross sections of
single-particle production via resolved photons in collisions at HERA.
Transverse-momentum and rapidity distributions are presented and the scale
dependence is studied. The results are compared with first experimental data
from the H1 Collaboration at HERA.Comment: 11 pages with 15 uuencoded PS figures. Preprint DESY 93-03
- …