Magnetometer deployment mechanism for Pioneer Venus

A three segment, 15-foot boom mechanism was developed to deploy magnetometers from the Pioneer Venus orbiter spinning shelf. The stowage mechanism is designed to contain the magnetometers during launch and to deploy these instruments by centrifugal force upon pyrotechnic release. Unique graphite-epoxy boom segments are used for a lightweight design with sufficient strength to withstand a 7.5 g orbit insertion force while extended. The detailed design is described, along with the test methods developed for qualification in a one-g field

Ablation effects in oxygen-lead fragmentation at 2.1 GeV/nucleon

The mechanism of particle evaporation was used to examine ablation effects in the fragmentation of 2.1 GeV/nucleon oxygen nuclei by lead targets. Following the initial abrasion process, the excited projectile prefragment is assumed to statistically decay in a manner analogous to that of a compound nucleus. The decay probabilities for the various particle emission channels are calculated by using the EVAP-4 Monte Carlo computer program. The input excitation energy spectrum for the prefragment is estimated from the geometric ""clean cut'' abrasion-ablation model. Isotope production cross sections are calculated and compared with experimental data and with the predictions from the standard geometric abrasion-ablation fragmentation model

Optical-model abrasion cross sections for high-energy heavy ions

Within the context of eikonal scattering theory, a generalized optical model potential approximation to the nucleus-nucleus multiple scattering series is used in an abrasion-ablation collision model to predict abrasion cross sections for relativistic projectile heavy ions. Unlike the optical limit of Glauber theory, which cannot be used for very light nuclei, the abrasion formalism is valid for any projectile target combination at any incident kinetic energy for which eikonal scattering theory can be utilized. Results are compared with experimental results and predictions from Glauber theory

Harmonic well matter densities and Pauli correlation effects in heavy-ion collisions

A generalized optical model heavy ion reaction theory is extended to include correlation effects between projectile and target constituents according to the Pauli exclusion principle. These correlation effects are significant for accurately predicting cross sections for projectile nucleus abrasions, but are relatively unimportant for determining total and absorption cross sections for heavy ion collisions. For lighter nuclei, predictive capabilities were also improved by developing an analytic method for extracting their nuclear single particle density distributions from experimentally measured harmonic well charge density distributions. This improved theory is compared with previous theoretical predictions and recent experimental results

An initial assessment of the performance achieved by the Seasat-1 radar altimeter

The results of an initial on-orbit engineering assessment of the performance achieved by the radar altimeter system flown on SEASAT-1 are presented. Additionally, the general design characteristics of this system are discussed and illustrations of altimeter data product are provided. The instrument consists of a 13.5 GHz monostatic radar system that tracks in range only using a one meter parabolic antenna pointed at the satellite nadir. Two of its unique features are a linear FM transmitter with 320 MHz bandwidth which yields a 3.125 nanosecond time delay resolution, and microprocessor implemented closed loop range tracking, automatic gain control (AGC), and real time estimation of significant wave height (SWH). Results presented show that the altimeter generally performed in accordance with its orginal performance requirments of measuring altitude to a precision of less the 10 cm RMS, significant wave height to an accuracy of + or - 0.5 m or 10%, whichever is greater, and ocean backscatter coefficient to an accuracy of + or - 1 db, all over an SWH range of 1 to 20 meters

An assessment of transport coefficient approximations used in galactic heavy ion shielding calculations

An energy-dependent, perturbation expansion solution for heavy ion transport in one dimension is used to perform depth-dose calculations for 670/MeV nucleon Ne-20 beams incident upon a thick water target. Comparisons of predictions obtained by using typical energy-independent approximations and those obtained with fully energy-dependent input parameters are made. It is found that the calculated doses are underestimated when the energy-independent input approximations are used. The major source of error, however, is the lack of charge and mass conservation in the Silberberg-Tsao fragmentation parameters

Calculation of two-neutron multiplicity in photonuclear reactions

The most important particle emission processes for electromagnetic excitations in nucleus-nucleus collisions are the ejection of single neutrons and protons and also pairs of neutrons and protons. Methods are presented for calculating two-neutron emission cross sections in photonuclear reactions. The results are in a form suitable for application to nucleus-nucleus reactions

Cross section parameterizations for cosmic ray nuclei. 1: Single nucleon removal

Parameterizations of single nucleon removal from electromagnetic and strong interactions of cosmic rays with nuclei are presented. These parameterizations are based upon the most accurate theoretical calculations available to date. They should be very suitable for use in cosmic ray propagation through interstellar space, the Earth's atmosphere, lunar samples, meteorites, spacecraft walls and lunar and martian habitats

Calculation of two-neutron multiplicity in photonuclear reactions

The most important particle emission processes for electromagnetic excitations in nucleus-nucleus collisions are the ejection of single neutrons and protons and also pairs of neutrons and protons. Methods are presented for calculating two-neutron emission cross sections in photonuclear reactions. The results are in a form suitable for application to nucleus-nucleus reactions