Document Details


Title:
OPERATION SUN BEAM, SHOT SMALL BOY, PROJECT OFFICERS REPORT PROJECT 2.2: MEASUREMENT OF FAST-NEUTRON DOSE RATE AS A FUNCTION OF TIME (DELETED)
Author(s):
KRONENBERG, S [UNITED STATES ARMY ELECTRONIC LABORATORY]; MARKOW, B [UNITED STATES ARMY ELECTRONIC LABORATORY]; BALTON, I A [UNITED STATES ARMY ELECTRONIC LABORATORY]
Subject Terms:
SUNBEAM PROJECT; SMALL BOY EVENT; NEUTRONS; MEASURING METHODS; GAMMA RADIATION; CALIBRATION; DOSE RATES; RESEARCH PROGRAMS; DOMINIC II OPERATION
Document Location:
Location - NNSA/NSO Nuclear Testing Archive Address - P.O. Box 98521 City - Las Vegas State - NV Zip - 89193-8521 Phone - (702)794-5106 Fax - (702)862-4240 Email - CIC@NV.DOE.GOV
Document Type:
REPORT
Publication Date:
1963 Oct 11
Declassification Status:
Sanitized
Document Pages:
0080
Accession Number:
NV0051025
Document Number(s):
POR2210EX
Originating Research Org.:
UNITED STATES ARMY ELECTRONIC LABORATORY
OpenNet Entry Date:
1994 Aug 26
Description/Abstract:
FAST-NEUTRON INTENSITY AS A FUNCTION OF TIME WAS MEASURED AT 625,1600, AND 4.000 FEET FROM A SURFACE BURST, WITH THE USE OF A NEWLY DEVELOPED NEUTRON DETECTOR. PROJECT PERSONNEL ALSO ATTEMPTED TO MEAS URE THE FAST-NEUTRON SPECTRUM AS A FUNCTION OF TIME AT THE 1,600-FOOT STATION. THE FAST-NEUTRON INTENSITY WAS MEASURED WITH A GAMMA-COMPENS ATED NEUTRON-SENSITIVE SEMIRAD (SECONDARY-ELECTRON MIXED-RADIATION DOS IMETRY). BASICALLY, THE SEMIRAD IS A VACUUM DIODE. GAMMAS PRODUCE CO MPTON ELECTRONS IN THE WASS, WHICH, UPON LEAVING THE WALL, PRODUCE LOW -ENERGY SECONDARY ELECTRONS. THESE ELECTRONS ARE COLLECTED ON THE OTH ER ELECTRODE. TO MAKE THE SEMIRAD NEUTRON-SENSITIVE, THE EMITTING WAL L MUST BE MADE OF EITHER HYDROGEN-RICH MATERIAL OR FISSIONABLE MATERIA L. THE NEUTRONS THEN PRODUCE EITHER RECOIL PROTONS OR FISSION FRAGMEN TS, WHICH ON LEAVING THE WALL, PRODUCE LOW-ENERGY SECONDARY ELECTRONS THAT ARE COLLECTED. SINCE THE NEUTRON-SENSITIVE SEMIRAD IS ALSO GAMMA -SENSITIVE, A BUCKING ARRANGEMENT MUST BE USED WITH A NEUTRON-INSENSIT IVE SEMIRAD TO ELIMINATE THE GAMMA SENSITIVITY. THE SIGNAL FROM THIS DETECTOR WAS RECORDED ON BOTH OSCILLOSCOPES AND MAGNETIC TAPE. MEASUR EMENT OF THE NEUTRON SPECTRUM AS A FUNCTION OF TIME INVOLVED THE USE O F ANOTHER NOVEL DETECTOR. THE VERSION USED HERE HAD FIVE ELEMENTS. T HE INDIVIDUAL ELEMENT CONSISTS OF A RADIATOR (IN THIS CASE A HYDROGEN- RICH PLASTIC), AN ABSORBER (FIVE DIFFERENT THICKNESSES WERE USED), AND AN IONIZED-PARTICLE DETECTOR. PROTONS PRODUCED IN THE RADIATOR ARE A TTENUATED BY THE DIFFERENT THICKNESSES OF ABSORBER, DEPENDING ON THE P ROTON ENERGY. THE PROTONS ARE THEN DETECTED BY A SILICON-DIODE PARTIC LE DETECTOR. THE SIGNAL CURRENT CAN BE RELATED TO THE ORIGINAL NEUTRO N SPECTRUM BY SOLUTION OF THE EQUATION OBTAINABLE FROM THE THEORY OF T HE DEVICE. FAST-NEUTRON-INTENSITY DATA AS A FUNCTION OF TIME WERE OBT AINED AT ALL THREE STATIONS. THE DURATION OF THE FAST-NEUTRON ENVIRON MENT WAS MUCH SHORTER THAN ANTICIPATED. THE NEUTRON SIGNALS AT THE TW O CLOSER STATIONS SHOWED A RAPID RISE AND THEN DECAYED WITHIN APPROXIM ATELY 150 MICROSEC. THE SHARP RISE WAS APPARENTLY DETERMINED BY THE A RRIVAL OF THE AND THE RELATIVELY SLOW DECAY BY THE SCATTE RED NEUTRONS. THE PEAK DOSE RATES WERE AT 625 FEET AND AT 1,600 FEET. AT THE 4,000 FOOT STATION, THE 14 -MEV NEUTRONS ARRIVED SEPARATED IN TIME FROM THE FISSION NEUTRONS. FO R MEASUREMENT OF THE NEUTRON SPECTRUM AS A FUNCTION OF TIME, THE DATA RECOVERY WAS NOT COMPLETE; THUS, ANALYSIS WAS IMPOSSIBLE.


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