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OPERATION GREENHOUSE, SCIENTIVIC DIRECTOR'S REPORT OF ATOMIC WEAPON TESTS AT ENIWETOK, 1951: ANNEX 1.9 - AIR-DROP INSTRUMENTATION, PART II, TELLER-ALPHA (DELETED)

GRIER, H E [* EG+G]

GREENHOUSE OPERATION; RADIATION DETECTION; RESEARCH PROGRAMS; MEASURING INSTRUMENTS; DOG-0451 EVENT; EASY-0451 EVENT; GAMMA DETECTION

Location - DOE/NNSA 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 - NTA@NV.DOE.GOV

REPORT

1954 Jan 01

Sanitized

0030

NV0051029

WT108EX

* EG+G

1994 Aug 26

2003 Sep 18

THE TELLER-ALPHA TECHNIQUE RECORDS, BY PHOTOELECTRIC MEANS, A PORTION OF THE EXPONENTIAL RATE OF GROWTH OF LIGHT SURROUNDING THE DETONATING BOMB. THIS LIGHT IS CAUSED BY GAMMA RAYS EMERGING FROM THE CASE AND I S PRESUMABLY PROPORTIONAL AT EVERY INSTANT TO THE GAMMA FLUX AND THUS TO THE NEUTRON LEVEL WITHIN THE BOMB. A SIMILAR MEASUREMENT WAS MADE BY EDGERTON, GERMESHAUSEN & GRIER, INC. (EG+G) ON OPERATION SANDSTONE WITH RATHER POOR RESULTS (H.E. GRIER, E.H. EDGERTON, AND STAFF, SANDST ONE REPORT, VOL. 15, ANNEX 3, PART 1, SEPTEMBER 1948). SUBSEQUENT TO OPERATION SANDSTONE IT WAS FOUND THAT THE ERRONEOUS RESULTS COULD BE T RACED IN LARGE PART OT THE 931-A PHOTOMULTIPLIER TUBE USED AS A DETECT OR WHICH HAD A LIMITED RISE-TIME RESPONSE TO RAPIDLY CHANGING LIGHT SI GNALS. PRIOR TO OPERATION GREENHOUSE, EG+G WAS REQUESTED TO INVESTIGA TE THE FEASIBILITY OF MEASURING TELLER-ALPHA FROM AIRCRAFT PLACED NEAR LY OVERHEAD. LABORATORY INVESTIGATIONS OF THE PROPERTIES OF THE 931-A PHOTOMULTIPLIER REVEALED THAT THE RISE TIME IN THE OUTPUT SIGNAL COUL D BE DECREASED CONSIDERABLY BY OPERATING THE TUBE AT ABNORMALLY HIGH D YNODES INSTEAD OF THE TOTAL (NINE) BUILT INTO THE TUBE. IN THIS MANNE R IT WAS POSSIBLE TO MEASURE EXPONENTIAL RISES HOWEVER, THE TUBE WAS SO CLOSE TO INSTABILITY THAT THE ELECTRODE VOLTAGES COULD BE APPLIED FOR ONLY A FEW MICROSECONDS. A COMPROMISE WAS SOUGHT AND FOU ND. IN OPERATION GREENHOUSE 931-A PHOTOMULTIPLIER TUBES WERE USED AT ELECTRODE VOLTAGES COULD BE RECORDED AND SUCH THAT THE VOLT AGES COULD BE LEFT ON THE TUBE FOR SEVERAL SECONDS. SHORTLY BEFORE TH E OPERATION BEGAN, THE AIRCRAFT PARTICIPATION WAS ELIMINATED, AND THE DECISION WAS REACHED TO OPERATE THE TELLER-ALPHA EQUIPMENT AT GROUND S TATIONS. RECORDS WERE OBTAINED ON DOG AND EASY SHOTS; ON GEORGE SHOT THE PREVAILING AMBIENT LIGHT WAS TOO HIGH TO PERMIT A READING, AND ON ITEM SHOT THE EQUIPMENT WAS NOT OPERATED. THE MEASURED VALUES OF ALPH A ON DOG AND EASY SHOTS WERE FOUND TO BE THAN THE OFFICIAL VALUES RECORDED BY THE NAVAL RESEARCH LABORATORY--HALL BY STANDARD TEC HNIQUES. THREE POSSIBLE EXPLANATIONS FOR THE DISCREPANCIES HAVE BEEN PROPOSED: (1) THE LINEARITY OF THE PHOTOMULTIPLIER TUBE OPERATED UNDER THESE CONDITIONS HAS STILL NOT BEEN DEFINITELY PROVED; (2) THE MEASUR EMENT MAY HAVE BEEN MADE AT SUCH ALATE TIME THAT THE ALPHA HAD ACTUALL Y DECREASED TO THE INDICATED VALUE; AND (3) THERE IS IN ALL PROBABILIT Y A NONLINEAR ABSORPTION OF LIGHT BY THE ATMOSPHERE.