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COSMIC RAY PRODUCTION OF LOW ENERGY GAMMA RAYS

Technical Report ·
OSTI ID:4036481
An attempt was made to detect and measure any vertically incident flux of low-energy (0.15 to 10 Mev) gamma rays that might be present at high altitudes. The experiment consisted of a series of balloon flights carrying a phoswich gamma spectrometer with pulse height recording to altitudes of about 5.5 g/cm/sup 2/ atmosphere depth. Directional sensitivity was obtained by placing a lead collimating shield around the detector and by periodically opening and closing a lead shutter above the opening of the shield. At altitudes between 5.4 and 6.0 g/ cm/sup 2/ atmospheric depth the experiment yielded a value of 0.000 plus or minus 0.034 photons sec/sup -1/ cm/sup -2/ sterad/sup -/ s/sup 1/ for the vertical flux of gamma rays in the vicinity of 0.5 Mev energy. This is a null result; however, it places a new upper limit on the vertical gamma flux that is lower than any previously reported for this energy region. At lower altitudes it was observed that gamma rays are generated by cosmic rays in the atmosphere and in the collimating lead shield. At an atmospheric depth of 300 g/cm/sup 2/ the flux of gamma rays from the atmosphere was about 0.3 photons sec/sup -/1/sup >/cm/ sup -2/ sterad/sup -1/. There was found convincing evidence that the gamma rays of atmospheric origin were generated by the secondary nucleonic component and that they are not genetically related to the electromagnetic or''soft'' component of the secondary cosmic rays. (auth)
Research Organization:
Chicago. Univ. Enrico Fermi Inst. for Nuclear Studies
NSA Number:
NSA-15-017465
OSTI ID:
4036481
Report Number(s):
EFINS-61-3; AFOSR-405
Country of Publication:
United States
Language:
English

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Related Subjects

BALLOONS
COSMIC RADIATION
DECAY
ELECTRONS
ENERGY RANGE
INSTRUMENTS
INTERACTIONS
LEAD
LEVELS
MEASURED VALUES
NUCLEONS
PHOTONS
PHYSICS
PIONS
PRODUCTION
PULSES
RECORDING SYSTEMS
SCINTILLATION COUNTERS
SENSITIVITY
SHIELDING
SPECTROMETERS
STRATOSPHERE
VARIATIONS