Engineering topics
Publications and source records attributed to Ormes, J. F..
Review of some of the problems encountered in the development of an improved Cerenkov counter for high energy cosmic ray experiments, and discussion of the approaches used or contemplated for the solution of these problems. The solution is felt to be contingent upon a better UV-reflecting paint and an improved radiator and photomultiplier positioning.
Differential energy spectra of cosmic-ray protons and He nuclei have been measured for the first time by an ionization spectrometer flown at balloon altitudes. The energy range extended from 50 to more than 1000 GeV. The observed differential intensities can be represented with power-law spectra with a slope of -2.75 (plus or minus 0.03) for protons and of -2.77 (plus or minus 0.05) for He nuclei. The proton-to-He ratio is 26 (plus or minus 3) at 40 GeV/nucleon and is constant within errors up to 400 GeV/nucleon.
Differential energy spectra of cosmic ray protons and helium nuclei were measured by an ionization spectrometer flown at balloon altitudes. The energy range extended from 50 GeV to above 1000 GeV. The observed differential intensities can be represented with power law spectra with a slope of -2.75 + or - 0.03 for protons and of -2.77 + or - 0.55 for helium nuclei. The proton to helium ratio is equal to 26 + or - 3 at 40 GeV/nuc and is constant within errors up to 400 GeV/nuc.
The primary cosmic ray proton and He spectra from 50 GeV to 2000 GeV have been measured by an ionization spectrometer flown on a balloon. At low energies, the energies of individual events are determined to within + or - 30%. At higher energies, the cascade is not fully contained within the four mean free path thick spectrometer and the problems of estimating the energies of these events are discussed. The proton spectrum continued with constant exponent = -2.7 + or - 0.1 up to energies greater than 1000 GeV. This spectrum was in agreement with the results at the low energies. There was no evidence for a spectral break at about 1000 GeV observed.
Experimental results from the balloon borne ionization spectrometer have enabled the extension of the measurement of the energy spectra of cosmic rays to 10 to the 12th power eV. The exposure factor for this flight was 1825 sq m/sr/sec and approximately 10,000 nuclei with Z greater than or equal to 3 have been observed. Differential spectra of individual nuclei from lithium to oxygen and from groups of nuclei with Z = 10-14, 15-19, 20-23, and 24-30 energy range 2 x 10 to the 10th eV to 10 to the 12th eV are described in a power law representation. Results indicate that the composition of galactic cosmic rays remains similar to that observed at lower energies. These results from direct measurements provide evidence for the processes of source acceleration with interstellar propagation remaining essentially energy independent up to 10 to the 12th power eV.
An ionization spectrometer consisting of 12 layers of tungsten each 6.13 gm cm/2 thick and 7 iron modules each 70 gm cm/2 thick was flown in a balloon at an altitude of 6 gm cm/2 for 16 hours. The distributions of the first interaction points are used to determine the mean free path of the incident particles. At energies of 20 GeV the proton m.f.p. of 140 gm cm/2 is in agreement with that of other workers. The m.f.p.'s of heavy nuclei have been determined as a function of energy up to a total energy of 1000 GeV. These results are compared with the overlap model of nucleus-nucleus collisions. For C nuclei interacting with W the overlap parameter is -2.6 x 10/13 cm. The energy dependence of this parameter is discussed.
An ionization spectrometer consisting of 10.8 radiation lengths of tungsten and 35 radiation lengths of iron has been used to determine the energy spectrum of cosmic ray electrons above 10 GeV. The spectrometer was calibrated with electrons from 5.4 to 18 GeV and then flown at an altitude of 6 gm-cm/2 for 16 hours. Separation of electron initiated events from proton events was achieved by utilizing starting point distributions, the shower development in tungsten, and the energy deposited in the large thickness of iron absorber. The exponent of the differential energy spectrum of the electrons is -3.1 + or - 0.2 while the exponent of the background is consistent with the proton exponent of -2.7 + or -0.2.
The survival of high Z nuclei in the X-ray photon field of a pulsar is investigated. For heavy nuclei with energies greater than or equal to 100 GeV/nucleon, 100 keV X-ray photons have sufficient energy to cause photodisintegration with cross sections of approximately 10 to the minus 25th power sq cm. Using the observed properties of the Crab pulsar, extrapolation back to epochs when the pulsar was more active indicates that the photon field is sufficiently dense to prevent the acceleration of heavy nuclei within the velocity of light cylinder. On this model, the upper limit on the energy of the escaping nuclei varies with time. The models for cosmic ray acceleration in supernova explosions or by pulsars will be related to experimental observations.
Design of experiments and systems for HEAO to determine composition and spectra of high energy cosmic rays
Calibration of high energy cosmic ray experiment
Primary cosmic rays balloon-borne charge composition detector in 3-30 Z range
Large area high resolution cosmic ray charge composition detector
High energy primary cosmic ray program of Goddard Space Flight Center involving charge composition and energy spectra studies in balloon and satellite experiments
Interstellar propagation effect on spectra and charge ratios due to ionization energy loss and nuclear spallation during traversal of matter
Balloon and satellite flight program to determine charge composition of primary cosmic rays
Primary cosmic ray nitrogen nuclei intensity and spectrum measured by balloons and Pioneer 8 space probe, obtaining abundance difference from solar atmosphere
Energy spectra comparison of cosmic ray helium and heavy nuclei
Energy spectra of carbon and oxygen nuclei in primary cosmic radiation, comparing results to earlier measurements and satellite observation