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At least 451 records · Page 25

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NASA NTRS1985

Tables of nuclear cross sections for galactic cosmic rays: Absorption cross sections

A simple but comprehensive theory of nuclear reactions is presented. Extensive tables of nucleon, deuteron, and heavy-ion absorption cross sections over a broad range of energies are generated for use in cosmic ray shielding studies. Numerous comparisons of the calculated values with available experimental data show agreement to within 3 percent for energies above 80 MeV/nucleon and within approximately 10 percent for energies as low as 30 MeV/nucleon. These tables represent the culmination of the development of the absorption cross section formalism and supersede the preliminary absorption cross sections published previously in NASA TN D-8107, NASA TP-2138, and NASA TM-84636.

Townsend, L. W.↗

NASA NTRS1985

Primary cosmic ray spectrum in the 10 to the 12th power - 10 to the 16th power eV energy range from the NUSEX experiment

A primary cosmic ray spectrum was derived which fits both experimental multiple muon rates and the all-nucleon flux derived from the single muon intensities underground. In the frame of the interaction model developed by Gaisser, Elbert and Stanev, it is possible to reproduce NUSEX muon data with a primary composition in which the iron spectrum is only slightly flatter than the proton one. This result rules out the popular idea that the primary composition varies drastically with increasing energy, leading to the dominance of heavier nuclei at energies 10 to the 15th power to 10 to the 16th power eV.

Battistoni, G.↗

NASA NTRS1985

Propagation and secondary production of low energy antiprotons in the atmosphere

Current theories, in which the observed antiproton component is attributed strictly to secondary production in high energy inelastic collisions of protons with the interstellar medium or the atmosphere, apparently fail to explain the relatively high p vertical intensities measured at mountain and balloon altitudes. Therefore, a more careful calculation of the theoretical secondary intensity spectra is required before more exotic sources for these excess p's can be explored. A one dimensional diffusion equation is used to calculate the expected vertical intensity of p's due only to secondary production in the atmosphere; any assumed primary p spectrum is also included. Two adjustable parameters, the inelasticity and charge exchange in nucleon-nucleus collisions, were included in the algorithm. In order to obtain an independent estimate of their values the proton vertical intensities in the atmosphere were calculated, adjusting the parameters until the curves fit the experimental proton data, and then assumed that these values were identical in antinucleon-nucleus collisions.

Bowen, T.↗

NASA NTRS1985

Search for solar neutrons using NM-64 equipment

Two years (1980 to 1982) neutron monitor data from the Chacaltaya (geographic coordinates: N16.32 deg W68. 15 deg; cutoff rigidity: 13.1 GV; altitude: 5,300 m a.s.l.) station has been scanned; the sampling time of the 12NM-64 neutron monitor is 5 min. The nucleonic component increases have been correlated with 66 hard X-, gamma rays satellite data from solar origin, as reported by several groups. Typical neutron monitor time profiles of the events are presented. Chree-analysis was performed discriminating the events according to its solar coordinates. Ground data from solar limb locii are more enhanced at the time of the onset than other geometrically visible flares. Chree histograms of neutron monitor output profiles are also presented from geometrically invisible events from the Chacaltaya station.

Martinic, N. J.↗

NASA NTRS1985

Elemental abundance differences between nuclei acclerated in CIR shocks and solar flares

Measurement of the ratios of nuclear abundances H/He, CNO/Fe-group and the Fe-group/HE for 51 passages of Corotating Interaction Regions (CIRs) at 1 AU, and measurement of these ratios from 620 solar flares in the energy range 0.6 to 4 MeV per nucleon, show that CIR shock acceleration alone does not change significantly these ratios from the values they have for solar system abundances or the solar wind. The solar flare ratios continue to reflect strong biases in the abundances, consistent with requirements for multistage acceleration rpocesses at the Sun.

Dietrich, W. F.↗

NASA NTRS1985

Secondary to primary ratio and the continuous acceleration

A general formula for the sec/prim ratio, independently of any details of the propagation and acceleration model is presented. In the limit of equal fragmentation paths for primaries and secondaries, this ratio at a given momentum nucleon is proportional only to the mean path of the observed primaries at that moment. It is shown that it is unlikely to get a decreasing sec/prim ratio with energy if an acceleration process takes place during particle propagation in the interstellar medium (ISM).

Giler, M.↗

NASA NTRS1985

Mass resolution optimization in a large isotopic composition experiment

A range-energy experiment was built to measure the isotopic composition of galactic cosmic rays. An enrichment of neutron rich isotopes, 22Ne and (25Mg + 26Mg) in particular, when compared to the solar composition is shown. A rich statistics measurement of these and other neutron-rich isotopes in the galactic flux yields information to the source of these particles. A computer simulation of the experiment was used to estimate the instrument resolution. The Cherenkov detector light collection efficiency, was calculated. Absorption of light in the radiator was considered to determine the optimum Cherenkov medium thickness. The experiment will determine the isotopic composition for the elements neon through argon in the energy range 300 to 800 MeV per nucleon.

Esposito, J. A.↗

NASA NTRS1985

Transient cosmic ray increase associated with a geomagnetic storm

On the basis of worldwide network data of cosmic ray nucleonic components, the transient cosmic ray increase due to the depression of cosmic ray cutoff rigidity during a severe geomagnetic storm was investigated in terms of the longitudinal dependence. Multiple correlation analysis among isotropic and diurnal terms of cosmic ray intensity variations and Dst term of the geomagnetic field is applied to each of various station's data. It is shown that the amplitude of the transient cosmic ray increase associated with Dst depends on the local time of the station, and that its maximum phase is found in the evening sector. This fact is consistent with the theoretical estimation based on the azimuthally asymmetric ring current model for the magnetic DS field.

Kudo, S.↗

NASA NTRS1985

Heavy Cosmic Ray Measurement Aboard Spacelab-1

A stack of CR-39 plastic track detectors was exposed to cosmic radiation during the 10 days mission aboard Spacelab-1. A part of the stack was rotated one revolution within 7 days. The impact time of most of the particles was correlated with the orbit position of the shuttle and thus with geomagnetic field parameters. The analysis of heavy particles with charge Z greater than or equal to 6 in the energy range 50-150 MeV per nucleon with special emphasis on geomagnetically forbidden particles is reported.

Beaujean, R.↗

NASA NTRS1985

Ringlike inelastic events in cosmic rays and accelerators

In cosmic rays and in accelerators there were observed single inelastic processes with densely produced (azimuthally isotropic) groups of particles exhibiting spikes in the pseudorapidity plot of an individual event (i.e. ringlike events). Theoretically the existence of such processes was predicted as a consequence of Cerenkov gluon radiation or, more generally, of deconfinement radiation. Nowadays some tens of such events have been accumulated at 400 GeV and at 150 TeV. Analyzing ringlike events in proton-nucleon interactions at 400 GeV/c it is shown that they exhibit striking irregularity in the positions of pseudorapidity spikes' centers which tend to lie mostly at 55,90 and 125 deg in cms. It implies rather small deconfinement lengths of the order of some fermi.

Dremin, I. M.↗

NASA NTRS1985

Characteristics of central collision events in Fe-nucleus interactions for 20 - 60 GeV/nucleon

A counter emulsion hybrid chamber in Japanese-American Cooperative Emulsion Experiment (JACEE-3) was flown on a balloon at the altitude (5.4 g/sq cm) in 1982 with the objective of probing the heavy nuclear collisions above 20 GeV per nucleon. In the energy region, it is suggested that nucleus-nucleus collisions provide dense collisions complex through compression and secondary particle production. In the lower energy region, an evidence of collective flow has been reported. And also, at higher energy region, it has been argued that nucleus has rather large stopping power. In this paper, the high multiplicity characteristics of Fe nucleus central collisions with energies 20 to 50 GeV/nucleon are presented. This is considered to be relevant to compressibility and collective flow of nuclear matter.

Burnett, T. H.↗

NASA NTRS1985

Forward particle production in inelastic Ne-22 inteVractions in emulsion at 4.1 A Ge/c

The collisions of high energy nuclei are likely to be the subject of intense experimental investigation in the near future. The results are presented on multiple meson production in forward cone in inelastic interactions of Ne-22 nuclei in emulsion at a primary momentum 4.1 GeV/c per nucleon. The detailed characteristics of particle production and the fragmentation processes in collisions of Ne-22 nuclei in emulsion are described.

Source record↗

NASA NTRS1985

Study of hadron bundles observed in Chacaltaya two-story emulsion chamber

The existence of hadron-rich families associated with few gamma-ray emission named Centauro and Mini-Centauro phemonena was reported. It was investigated whether these are produced by the special type of interaction different from the ordinary pion multiple production or not. The experimental results are compared with simulation calculation based on ordinary multiple pion production model. Both hadron multiplicity distribution, obtained from the present observation and the simulation calculation, show almost the same distribution which means that hadron bundles of such smaller multiplicities are considered to originate from successive interactions of surviving nucleon with the nature of multiple production during passage through the atmosphere.

Aoki, H.↗

NASA NTRS1985

A possible EAS array above the Soudan 2 detector

Multiple high energy muons, when studied with a large area detector, can be useful in the study of the composition of cosmic rays at energies approx. 10 14 eV. The Soudan II detector, primarily designed to detect nucleon decay, is located approx. 600 m deep underground and has dimensions of 16m x 8m x 5m (height), and is made up of drift tubes. The minimum muon energy needed to penetrate that depth is approximately 500 GeV. A set of simulated cosmic ray showers was set up to calculate the rate of muon associated events, using a trigger array with the number of detectors varying from 37 to 127 (the radius of acceptance varying from 50m to 100m). The number used in the calculations is given. The association rate is seen to be a strong function of the multiplicity of muons in the detector. The difference in the rates of association of proton and nuclei induced showers rises rapidly with multiplicity.

Sivaprasad, K.↗

NASA NTRS1985

Nineteenth International Cosmic Ray Conference. HE Sessions, Volume 8

Papers submitted for presentation at the 19th International Cosmic Ray Conference are compiled. The present volume contains papers addressing high energy interactions and related phenomena. Specific topic areas include muons, neutrinos, magnetic monopoles, nucleon decay, searches for new particles, and acoustic and thermoluminescence detection techniques.

Jones, F. C.↗

NASA NTRS1985

Muon and neutrino results from KGF experiment at a depth of 7000 hg/square cm

The KGF nucleon decay experiment at a depth of 7000 hg/sq cm has provided valuable data on muons and neutrinos. The detector comprised of 34 crossed layers of proportional counters (cross section 10 x 10 sq cm; lengths 4m and 6m) sandwiched between 1.2 cm thick iron plates can record tracks of charged particles to an accuracy of 1 deg from tracks that traverse the whole of the detector. A special two-fold coincidence system enables the detector to record charged particles that enter at very large zenith angles. In a live time of 3.6 years about 2600 events have been recorded. These events include atmospheric muons, neutrino induced muons from rock, stopping muons, showers and events which have their production vertex inside the detectors. The results on atmospheric muons and neutrino events are presented.

Krishnaswamy, M. R.↗

NASA NTRS1985

Multimuons events and primary composition

Nucleon decay detectors at large depths offers now a total area larger than 1000 sq m to registrate muons of energy exceeding 1 TeV. Near complete high energy muon families are detected in those arrays. An extensive 3D Monte-Carlo simulation was conducted in view to understand the spatial distribution of those events and the possible link with elementary act or primary composition. As pion or kaon parents have a very small decay probability at so high energy, multimuon phenomena occurs at high altitude where the atmospheric density is small after the most energetic collisions.

Acharya, B. S.↗

NASA NTRS1985

Search for stellar collapse with the MACRO detector at Gran Sasso

It is viewed that in stellar evolution stars in the range of 8 to 12 solar masses evolve gradually as increasingly heavier nuclei are produced and then consumed in a series of exothermic thermonuclear processes ultimately leading to the formation of a core composed almost entirely of nickel and iron. When the mass of this hot iron-nickel core reaches the critical value of approximately 1.4 solar masses, electron degeneracy pressure is no longer able to support the outer layers of the star and a collapse process begins. Since the core has exhausted its thermonuclear fuel, further stages of thermonuclear burning cannot prevent a runaway collapse. As the density reaches 10 to the 10th power gm sub/cm at a temperature near 10 to the 10th power k, most of the heavy nuclei are dissociated into free nucleons and electron capture on free protons leads to a decrease in the degeneracy pressure and further acceleration of the collapse process. Although this general picture has received substantial confirmation over the past two decades with the discovery of radio pulsars (neutron stars), X-ray pulsars (accreting binary neutron stars) and Cyg X-1 (probably an accreting black hole), an actual neutrino burst is not yet convincingly detected.

Steinberg, R.↗