scholarly journals Gas-Čerenkov Detector for 10 to 100 MeV Gamma Rays

1971 ◽  
Vol 41 ◽  
pp. 77-78 ◽  
Author(s):  
H. Helmken ◽  
J. Hoffman
Keyword(s):  
Gamma Radiation ◽  
Point Source ◽  
Gamma Rays ◽  
Angular Resolution ◽  
Galactic Plane ◽  
Plastic Scintillator ◽  
Spectral Information ◽  
Cerenkov Detector ◽  
Half Angle ◽  
Cerenkov Light

A gas-Čerenkov detector sensitive to gamma radiation above 10 MeV is currently undergoing final testing. The detector relies on the conversion and Compton scattering of gamma rays in a plastic scintillator and detecting the resulting electrons via the Čerenkov light they emit in a 2-m propane-gas column. Spectral information can be attained by varying gas pressure during the flight. The present detector is approximately 34″ in diameter, 91″ in length and weight 450 lb. At 20 MeV, an angular resolution of 6° half angle is expected. With an efficiency of 1 to 2%, a 10 hr balloon-borne system should achieve a point-source sensitivity of approximately 5× 10−5 photon cm−2 s−1 above 20 MeV. A satellite version of the detector is expected to have a sensitivity of approximately 1.3 × 10−5 photon cm−2 s−1 above 10 MeV for a 1-month galactic-plane scan mode. (Helmken and Hoffman, 1970.)

Search for point sources of neutral cosmic rays above 1012 eV

1968 ◽  
Vol 46 (10) ◽  
pp. S81-S83 ◽  
Author(s):  
Hugh S. Tornabene ◽  
Frank J. Cusimano
Keyword(s):  
Cosmic Rays ◽  
Gamma Rays ◽  
Angular Resolution ◽  
High Energy ◽  
Point Sources ◽  
Half Maximum ◽  
Air Showers ◽  
Arrival Times ◽  
Right Ascension ◽  
Cerenkov Light

A new installation for the detection of Cerenkov light from extensive air showers is being used to search for point sources of high-energy neutral cosmic rays. By measuring the relative arrival times of the Cerenkov light front at four well-spaced independent light detectors, an area of sky is examined simultaneously, with angular resolution near 1.5° half-width at half-maximum and energy threshold to gamma rays near 2 × 1012 eV. Results from preliminary scans of 3C144, 3C157, 3C219, 3C274, 3C295, and the constellation of Leo near declination 20° and right ascension 1100 h are given.

scholarly journals Galactic plane gamma-radiation

1979 ◽  
Vol 230 ◽  
pp. 597 ◽  
Author(s):  
R. C. Hartman ◽  
D. A. Kniffen ◽  
D. J. Thompson ◽  
C. E. Fichtel ◽  
H. B. Ogelman ◽  
...  
Keyword(s):  
Gamma Radiation ◽  
Galactic Plane

scholarly journals IV. Effect of 60Co gamma rays on survival rate of China aster plants (Callistephus chinensis Nees) in M1 generations - under field conditions

2013 ◽  
Vol 35 (2) ◽  
pp. 277-283
Author(s):  
A. Wosińska
Keyword(s):  
Survival Rate ◽  
Gamma Radiation ◽  
Gamma Rays ◽  
Lethal Effect ◽  
Field Conditions ◽  
Considerable Decrease ◽  
Planting Time ◽  
Variety Effect ◽  
China Aster ◽  
Different Doses

Studies were undertaken on the effect of different doses of gamma radiation on survival rate of plants (germinated from irradiated seeds) for 5 China aster varieties specified at florescence time. During their growth under field conditions (from planting time to blooming) lethal effect of the radiation occurred in plants of all varieties and its level depended on dose and variety. Effect of 3 kR and 6 kR doses differed depending on variety and was not always harmful, but following irradiation with doses exceeding 6 kR a considerable decrease in survival rate was observed. Radioresistance of studied varieties - measured both: by LD<sub>50</sub> and LD<sub>l00</sub> - differed; depending on variety, LD<sub>50 </sub>and LD<sub>l00</sub> values fluctuated: from 6 to 9 kR and 12 to 15 kR respectively.

Evaluation of the effect of gamma rays on the venom of Vipera lebetina by biochemical study

2003 ◽  
Vol 81 (12) ◽  
pp. 1110-1117 ◽  
Author(s):  
Nouara Bennacef-Heffar ◽  
Fatima Laraba-Djebari
Keyword(s):  
Gamma Radiation ◽  
Gamma Rays ◽  
Biochemical Characterization ◽  
Biochemical Study ◽  
Gel Filtration ◽  
Public Health Problem ◽  
Phospholipase A ◽  
Snake Bites ◽  
Vipera Lebetina

Snake bites represent a serious public health problem in many areas of the world. In Algeria, two widespread snakes are Vipera lebetina and Cerastes cerastes. Vipera lebetina venom causes local hemorrhage and necrosis, and it may lead to permanent limb loss. The principal causes of mortality after snakebites are acute renal failure and hemorrhage, which occur not only locally, at the site of the bite, but also systemically, contributing to the cardiovascular shock characteristic of severe envenomation. Gamma radiation has been shown to be effective for attenuating venom toxicity. Vipera lebetina venom was irradiated with two doses of gamma rays (1 and 2 kGy) from a 60Co source, and the venom's toxic, enzymatic, and structural properties were analyzed. Intraperitoneal injection of the irradiated venoms (100–500 µg/20 g mouse body mass) revealed a significant decrease of the toxicity. Irradiated venoms with 1 and 2 kGy doses were four and nine times less toxic, respectively, than the native venom. A biochemical characterization of in vitro enzymatic activities was performed. Vipera lebetina displayed in vitro caseinolytic, amidolytic, esterasic, coagulant, and phospholipase A2 activities. Caseinolytic, amidolytic, esterasic, and coagulative activities were reduced for the irradiated venoms; only phospholipase A2 activity was abolished in the irradiated venom with a dose of 2 kGy. The native and irradiated venoms were separated by gel filtration and electrophoresis. Chromatographic and electrophoretic profiles were drastically changed as compared with the native venom. Vipera lebetina venom detoxified by gamma rays was used for active immunization, and the presence of antibody in the immune sera was detected by ELISA. The immunogenic properties were preserved and the antisera obtained with the irradiated venoms could cross-react. Antisera were able to neutralize the toxic effect of V. lebetina native venom. These results indicate that irradiation of V. lebetina venom with a dose of 2 kGy can promote a significant detoxification, keeping the immunological properties intact.Key words: Vipera lebetina venom, gamma radiation, enzymes, detoxification, immune sera, immunoreactivity.

scholarly journals Measuring and calibrating galactic synchrotron emission

2008 ◽  
Vol 4 (S259) ◽  
pp. 603-612 ◽  
Author(s):  
Wolfgang Reich ◽  
Patricia Reich
Keyword(s):  
Large Scale ◽  
Angular Resolution ◽  
Galactic Plane ◽  
Synchrotron Emission ◽  
Diffuse Emission ◽  
Sky Surveys ◽  
Zero Level ◽  
The Galaxy ◽  
Scale Properties ◽  
Relative Measurements

AbstractOur position inside the Galaxy requires all-sky surveys to reveal its large-scale properties. The zero-level calibration of all-sky surveys differs from standard ‘relative’ measurements, where a source is measured in respect to its surroundings. All-sky surveys aim to include emission structures of all angular scales exceeding their angular resolution including isotropic emission components. Synchrotron radiation is the dominating emission process in the Galaxy up to frequencies of a few GHz, where numerous ground based surveys of the total intensity up to 1.4 GHz exist. Its polarization properties were just recently mapped for the entire sky at 1.4 GHz. All-sky total intensity and linear polarization maps from WMAP for frequencies of 23 GHz and higher became available and complement existing sky maps. Galactic plane surveys have higher angular resolution using large single-dish or synthesis telescopes. Polarized diffuse emission shows structures with no relation to total intensity emission resulting from Faraday rotation effects in the interstellar medium. The interpretation of these polarization structures critically depends on a correct setting of the absolute zero-level in Stokes U and Q.

scholarly journals Investigation of the Power of Resolution of a Spark Chamber for Gamma-Ray Astronomy

1971 ◽  
Vol 41 ◽  
pp. 73-74
Author(s):  
H. A. Mayer-Hasselwander ◽  
K. Pinkau ◽  
K. H. Schenkl ◽  
W. Voges ◽  
H. J. Schneider
Keyword(s):  
Monte Carlo ◽  
Gamma Rays ◽  
Gamma Ray ◽  
Angular Resolution ◽  
Monte Carlo Calculation ◽  
Gamma Ray Astronomy ◽  
Calculation Technique

The registration of gamma rays in a spark chamber has been simulated by Monte-Carlo-calculation technique. The spark chamber pictures of these gamma-ray events having a known energy and direction of incidence have been analysed for determinability of direction of incidence. The values obtained for angular resolution depending on energy are compared with values derived by other authors.

scholarly journals Investigation of the Structural Changes and Catalytic Properties of FeNi Nanostructures as a Result of Exposure to Gamma Radiation

Crystals ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 254
Author(s):  
Daryn B. Borgekov ◽  
Maxim V. Zdorovets ◽  
Dmitriy I. Shlimas ◽  
Artem L. Kozlovskiy
Keyword(s):  
Gamma Radiation ◽  
Point Defects ◽  
Gamma Rays ◽  
Structural Changes ◽  
Catalytic Properties ◽  
Structural Characteristics ◽  
Catalytic Reactions ◽  
Radiation Doses ◽  
Crystallite Orientation ◽  
Complete Destruction

The paper presents the results of changes in the structural characteristics, and the degree of texturing of FeNi nanostructures close in composition to permalloy compounds as a result of directed modification by gamma radiation with an energy of 1.35 MeV and doses from 100 to 500 kGy. The choices of energy and radiation doses were due to the need to modify the structural properties, which consisted of annealing the point defects that occurred during the synthesis along the entire length of the nanotubes. The initial FeNi nanostructures were polycrystalline nanotubes of anisotropic crystallite orientation, obtained by electrochemical deposition. The study found that exposure to gamma rays led to fewer defects in the structure, and reorientation of crystallites, and at doses above 300 kGy, the presence of one selected texture direction (111) in the structure. During tests of the corrosion resistance of synthesized and modified nanostructures in a PBS solution at various temperatures, it was found that exposure to gamma rays led to a significant decrease in the rate of degradation of nanotubes and an increase in the potential life of up to 20 days. It was established that at the first stage of testing, the degradation of nanostructures is accompanied by the formation of oxide inclusions, which subsequently lead to the formation of pitting corrosion and subsequent partial or complete destruction of the nanostructures. It is shown that gamma radiation is promising not only for targeted modification of nanostructures and increasing resistance to degradation, but also for increasing the rate of catalytic reactions of the PNA-PPD type.

WSRT 21-cm continuum field in Cygnus OB2: in search of more Wolf-Rayet stars

1999 ◽  
Vol 193 ◽  
pp. 103-104
Author(s):  
Diah Y.A. Setia Gunawan ◽  
Karel A. van der Hucht ◽  
A. Ger de Bruyn ◽  
Peredur M. Williams
Keyword(s):  
Point Source ◽  
Stellar Wind ◽  
Noise Level ◽  
Angular Resolution ◽  
Ob Stars ◽  
Near Ir ◽  
Continuum Field

We present a deep look into the Cygnus OB2 region using the WSRT. A 2° x 2° map of the optically highly-obscured region was obtained at 1400 MHz, with a noise level down to 0.2 mJy and an angular resolution of 1″. We will compare the resulting radio point source list with optical and near-IR catalogues, in order to identify stellar wind sources like WR and OB stars.

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