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  • Other Sources  (4)
  • 1985-1989  (4)
  • 1
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    Observation of hard X-rays from the Crab pulsar and A0535+26 (1985)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The Crab pulsar PSR0531+21 was observed in a balloon flight from the Xianghe Balloon Station (China). Data were obtained in the range 20 to 200 keV with a poswish hard X-ray telescope which comprised a 150 sq cm primary crystal of 5 mm thick CsI(T1) which actively shielded the lower 2 pi steradians by a 5 cm thick NaI(T1) crystal. The scintillation pulses originating in CsI and NaI crystals are distinguished by pulse shape discrimination. The telescope has a field of view of approximately 4 deg H psi H pi determined by graded shield and collimator. The effective geometric area of the detector is 116 sq cm. It is noted that when folding a data flow on a long period interference from the data acquisition, transmission and recording system considerably affect the result.
    Keywords: SPACE RADIATION
    Type: OG-2.3-7 , 19th Intern. Cosmic Ray Conf - Vol. 1; p 149-150; NASA-CP-2376-VOL-1
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 2
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    An approach of reducing the background induced by neutrons (1985)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The background induced by interactions of neutrons with detector material (and shield material) is difficult to be rejected. It is one of the most important factors to affect the sensitivity of a balloon-borne gamma-ray astronomical telescope. The main component of neutron flux at the major detector of the telescope is incident neutrons, that consists of atmospheric neutrons and neutrons locally produced in the balloon platform. Therefore, shielding the detector from incident neutrons is a possible way to reduce the background. NaI (T1) crystal is very widely used in gamma-ray astronomical telescopes. Through balloon-borne experiment it is shown that up 6 LiF shield is effective to reduce the background in NaI crystal.
    Keywords: SPACE RADIATION
    Type: OG-9.3-5 , 19th Intern. Cosmic Ray Conf - Vol. 3; p 371-374; NASA-CP-2376-VOL-3
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    NASA TECHNICAL REPORTS
  • 3
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    Sixty GHz IMPATT diode development (1985)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The objective of this program is to develop 60 GHz GaAs IMPATT Diodes suitable for communications applications. The performance goal of the 60 GHz IMPATT is 1W CW output power with a conversion efficiency of 15 percent and 10 year life time. During the course of the program, double drift (DD) GaAs IMPATT Diodes have been developed resulting in the state of the art performance at V band frequencies. A CW output power of 1.12 W was demonstrated at 51.9 GHz with 9.7 percent efficiency. The best conversion efficiency achieved was 15.3 percent. V band DD GaAs IMPATTs were developed using both small signal and large signal analyses. GaAs wafers of DD flat, DD hybrid, and DD Read profiles using molecular beam epitaxy (MBE) were developed with excellent doping profile control. Wafer evaluation was routinely made by the capacitance versus voltage (C-V) measurement. Ion mass spectrometry (SIMS) analysis was also used for more detailed profile evaluation.
    Keywords: ELECTRONICS AND ELECTRICAL ENGINEERING
    Type: NASA-CR-174969 , NAS 1.26:174969 , W-45797
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    NASA TECHNICAL REPORTS
  • 4
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    Acoustic response of manganese nodule deposits (1986)
    Society of Exploration Geophysicists
    In:  Geophysics, 51 (3). pp. 689-698.
    Details
    Publication Date: 2017-03-01
    Description: Backscattered acoustic intensities are studied analytically for manganese nodule deposits excited by a normally incident plane wave. The primary objective is to use this remote‐sensing technique to infer the nodule concentration as well as its size distribution from the frequency spectrum of the acoustic response. For sparse distributions of scatterers, multiple scattering theory has been used to obtain the coherent reflection and transmission coefficients from the sea floor covered with manganese nodules. The derived equations can also be used for densely distributed configurations when considering higher‐order statistics between scatterers. The validity of the formalism is examined by using the principle of conservation of energy and considering both the coherent and the incoherent intensities. Numerical results of acoustic intensities are highly frequency‐dependent, especially when the nondimensional frequency ka is greater than 1. The strength of the acoustic intensity is proportional to nodule concentration. Different size distributions of nodules can be distinguished through use of the intensity measurements. However only a minor difference is observed in the low‐frequency range between uniform and Rayleigh size distributions.
    Type: Article , PeerReviewed
    Format: text
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    PAPER (OCEANREP)
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