ABSOLUTE THERMAL NEUTRON FISSION YIELDS OF U²³³

Abstract

The absolute fission yields of 22 nuclides for~lled in the thermal neutron fission of U233 have been ~neasured radiochernically. Disintegration rates were measured by 4~ @-proportional counting techniques. The identity of each nuclide was established by che~llical separations and decay characteristics as determined by 4~ p-counting and -,-ray scintillation spectrometry. The reaction Co6"n,-,)Co" ovas used as a neutron flux monitor. Yields were calculated on the basis of u~U'33/ucC05q = 524/36.3.

A SURVEY AND EVALUATION OF U$sup 233$ FISSION YIELD DATA

“…The yields a t masses 128, 129, and 130 a r e t h e most significant, y i e l d s missing from t h e heavy peak. Two important nor&alization points i n t h e l i g h t peak are st masses 99 and 103; t h e previously-reported '(15, 30) absolute radiometric yields at these masses should perhaps be redetermined. I n addition, there a r e several yields missing from t h e v a l l e y of t h e mass-yield curve, and most of t h e reported Finally, t h e r e i s t h e problem of t h e f i n e s t r u c t u r e of the m a s s y i e l d curve.…”

“…The reported values f'rom Refs. 4, 18, and 2'7 have been *We chose not t o use t h e radiometric yields of Santry and Yaffe (30) because several of t h e i r values deviate widely *om t h e massspectrometric data, and it was not possible t o correct t h e i r d a t a i n any reasonable way t o agree with t h e mass-spectrometric r e s u l t s .…”

25 Jahre Kernspaltung. Methoden und Ergebnisse chemischer Studien

“…Zerfallsraten von Spaltproben lassen sich natürlich auch unmittelbar messen. 4ji-Proportionalzählrohre [131] haben freilich den Nachteil, daß sie nahezu gewichtslose Zählpräparate erfordern [132], die Spaltproben aber Träger enthalten; man kann nur einen sehr kleinen Teil der Probe zählen und braucht daher starke Aktivitäten [133,134]. Günstiger ist die 4:nß-y-Koinzidenzmethode [131,135] [139].…”