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The half-life of 90Sr and its yield from 233U fission
167
Letters to the editors
_.?_ t
._.__f---.r.__
___!
.-...
100
FIG.
2.-Partial
.+
..-. _.
I 200
___
--+_
._ _~_
xx)
-._(
+...-1
+_
I 400
---
I----
I
I
500
600
I
-
1 I
E, MeV cross-section do/dE for formation of spallation products from Z09Bias a function of the excitation energy (E) of the intermediate nucleus.
which these calculations were baaed could hardly be expected to apply to the whole range of mass numbers of the nuclear products considered. It may also be a result of the particular nature of the disintegration process at high excitation energies (the calculations took no account of the knock-out of heavy fragments). Other general features of this work were found to be in agreement with the results published in the earlier communication. A. V. KALIAMIN,A. N. MURIN, B. K. PREOBRAZHENSKII, N. E. TITOV REFERENCES B. K. and TITOVN. E., Izv. Akad. Nauk SSSR 4,518 (1955). 1. MURIN A. N., PRECIBRAZHENSKII B. K., IUTLANDOVI. A. and IAKIMOVM. A., Conference of the 2. MURIN A. N., PREOBRAZHENSKII U.S.S.R. Academy of Sciences on the Peaceful Uses of Atomic Energy, Moscow, Chemical Sciences Division. Consultants Bureau, New York (1955). B. K., L~LOVAI0. M. et al., Zh. neorg. khim. 1, 2294 (1956); 2, 1164 (1957). 3. PRE~BRAZHENSKH 4. RUD~TAMS. G., Phil. Mug. 46, 344 (1955); 44, 1131 (1953). 5. MURIN A. N. and IUTLANDOVI. A., Izv. Akad, Nauk SSSR 4,408 (1957). N. I. 6. KURCHATOVB. V., MEKHEDOVV. N., KUZNE~SOVAM. IA., KURCHATOVAL. N., BORXSOVA and CHISTIAKOVL. V., Conference of the U.S.S.R. Academy of Sciences on the Peaceful Uses of Atomic Energy, Moscow, Chemical Sciences Division. Consultants Bureau, New York (1955).
The half-life of TSr and its yield from 233U fission* (Received 18 September 1957) VALUFS of the half-life of O”Sr reported in the literature vary between 19.3 and 28 years.(l-s’ In this note, we report the results of some experiments which establish the value of this half-life more * Translated from Atomnnya Energiya 4, 198 (1958).
168
Letters to the editors TABLE I.-RESULTS 0~ THE **Sr AND YSr DETERMINATION Isotopic composition
Element
’ Atomic weight
:
’- ~ j
.~~.
_
j Fission / products
Natural strontium
__~
Strontium
i I
84 86 87 88 90
/ 0.055 f 0.001 ’ j ,it i 0.74 f 0.01 8.5 z!=0.2 -
-
_______
Number of strontium
_
1 Mixture of natural ,atoms in the irradiated / sample strontium and 1 fission products* ’ __ ~ .:
-
/ 1.01 & 0.015 /
0.08 h 0.004 0,061 * 0.005 1.66 ZtZ0.02
,1t
It
I
(1.625 h 0.062) x lo’*
j (1.61 & OO6) x lo’*
I I * In calculating the total quantity of fission products present in the sample (11.9 & 0.2 rng’Qi), account was taken of the 185 ~8 of natural strontium which was added. t Normalised to unity. exactly. Strontium was extracted from the fission products produced in a sample of Zs*U which had been irradiated in a neutron reactor. Some earlier work with this sample has been reported elsewhere.(4*6) The work reported here was carried out 4.25 years after the removal of the sample from the reactor-an interval of time which is long enough for practically all of the %r originally present in the sample to have decayed away. The *%r and %r content of the sample was determined by the isotopic dilution method, using a mass spectrometer type MS-l. The ion source was of the double filament surface ionization type.‘BJ The results of these measurements are given in Table 1. The decay rate of the strontium was measured with an end window beta-counter having a mica window of thickness 1.2 mg/cm$. The average of a series of three measurements gave a decay rate, dN/dt = (7-25 & 0.14) x lOlo decays per minute. This result gives the following half-life for ?Sr: 0.693 N T,,, = = 29.3 i- 1.6yr. dN/dt In calculating N, the number of ?Sr into account. The yields of *%r and fission products present in the sample by the parent nucleus ssKr, the yield was found to be (5.8 f 0.4) per cent,
atoms in the sample, the efficiency of the counter was taken 90Sr in naaU fission were calculated from the known amount of (11.9 & 0.2 mg). Neglecting the possibility of neutron capture of **Sr was found to be (5.3 + 0.3) per cent. The yield of 80Sr which result includes a decay correction.
Note: In a paper by ANIKINA and ERSHLER(‘)on the determination of the Wr yield in ss*U fission, the half-life of O”Sr was taken as 19.9 years. 0) When the results of these authors are re-calculated using the half-life obtained in this work (29.3 i 1.6 years) their yield of F4r becomes (6.3 & 0.3) per cent which, within the limits of the experimental errors, agrees with the result reported here. M. P. A&A, R. N. IVANOV, G. M. KUKAVADZE,B. V. ERSHLER REFERENCES 1. PAWERSR. I. and VOIGTA. F., Phys. Rev. 79, 175 (1950). 2. HUGHESD. J. and HARVEYJ. A., Neutron Cross Sections. McGraw-Hill, New York (1955). 3. STEINBERGE. P. and GLENDENINL. E., Proceedings of the First International Conference on the Peaceful Uses of Atomic Energy, Geneva, Vol. 7., p. 3. United Nations, New York (1956). 4. KUKAVADZEG. M., ANIKINAM. P., GOL’DINL. L. and ER~HLERB. V., Conference of the U.S.S.R. Academy of Sciences on the Peaceful Uses of Atomic Energy, Moscow, Chemical Sciences Division. Consultants Bureau, New York (1955). 5. KUKAVADZEG. M., GOL’DIN L. L., ANIKINA M. P. and ERWLER B. V., Proceedings of the First International Conference on the Peaceful Uses of Atomic Energy, Geneva, Vol. 4, p. 230. United Nations, New York (1956). 6. IVANOVR. N. and KUKAVADZEG. M., Prib. tekh. eksp. 1, 106 (1957). 7. ANIIUN~ M. P. and ER~HLERB. V., J. Nucl. Energy 6, 169 (1957).
Letters to the editors
_.?_ t
._.__f---.r.__
___!
.-...
100
FIG.
2.-Partial
.+
..-. _.
I 200
___
--+_
._ _~_
xx)
-._(
+...-1
+_
I 400
---
I----
I
I
500
600
I
-
1 I
E, MeV cross-section do/dE for formation of spallation products from Z09Bias a function of the excitation energy (E) of the intermediate nucleus.
which these calculations were baaed could hardly be expected to apply to the whole range of mass numbers of the nuclear products considered. It may also be a result of the particular nature of the disintegration process at high excitation energies (the calculations took no account of the knock-out of heavy fragments). Other general features of this work were found to be in agreement with the results published in the earlier communication. A. V. KALIAMIN,A. N. MURIN, B. K. PREOBRAZHENSKII, N. E. TITOV REFERENCES B. K. and TITOVN. E., Izv. Akad. Nauk SSSR 4,518 (1955). 1. MURIN A. N., PRECIBRAZHENSKII B. K., IUTLANDOVI. A. and IAKIMOVM. A., Conference of the 2. MURIN A. N., PREOBRAZHENSKII U.S.S.R. Academy of Sciences on the Peaceful Uses of Atomic Energy, Moscow, Chemical Sciences Division. Consultants Bureau, New York (1955). B. K., L~LOVAI0. M. et al., Zh. neorg. khim. 1, 2294 (1956); 2, 1164 (1957). 3. PRE~BRAZHENSKH 4. RUD~TAMS. G., Phil. Mug. 46, 344 (1955); 44, 1131 (1953). 5. MURIN A. N. and IUTLANDOVI. A., Izv. Akad, Nauk SSSR 4,408 (1957). N. I. 6. KURCHATOVB. V., MEKHEDOVV. N., KUZNE~SOVAM. IA., KURCHATOVAL. N., BORXSOVA and CHISTIAKOVL. V., Conference of the U.S.S.R. Academy of Sciences on the Peaceful Uses of Atomic Energy, Moscow, Chemical Sciences Division. Consultants Bureau, New York (1955).
The half-life of TSr and its yield from 233U fission* (Received 18 September 1957) VALUFS of the half-life of O”Sr reported in the literature vary between 19.3 and 28 years.(l-s’ In this note, we report the results of some experiments which establish the value of this half-life more * Translated from Atomnnya Energiya 4, 198 (1958).
168
Letters to the editors TABLE I.-RESULTS 0~ THE **Sr AND YSr DETERMINATION Isotopic composition
Element
’ Atomic weight
:
’- ~ j
.~~.
_
j Fission / products
Natural strontium
__~
Strontium
i I
84 86 87 88 90
/ 0.055 f 0.001 ’ j ,it i 0.74 f 0.01 8.5 z!=0.2 -
-
_______
Number of strontium
_
1 Mixture of natural ,atoms in the irradiated / sample strontium and 1 fission products* ’ __ ~ .:
-
/ 1.01 & 0.015 /
0.08 h 0.004 0,061 * 0.005 1.66 ZtZ0.02
,1t
It
I
(1.625 h 0.062) x lo’*
j (1.61 & OO6) x lo’*
I I * In calculating the total quantity of fission products present in the sample (11.9 & 0.2 rng’Qi), account was taken of the 185 ~8 of natural strontium which was added. t Normalised to unity. exactly. Strontium was extracted from the fission products produced in a sample of Zs*U which had been irradiated in a neutron reactor. Some earlier work with this sample has been reported elsewhere.(4*6) The work reported here was carried out 4.25 years after the removal of the sample from the reactor-an interval of time which is long enough for practically all of the %r originally present in the sample to have decayed away. The *%r and %r content of the sample was determined by the isotopic dilution method, using a mass spectrometer type MS-l. The ion source was of the double filament surface ionization type.‘BJ The results of these measurements are given in Table 1. The decay rate of the strontium was measured with an end window beta-counter having a mica window of thickness 1.2 mg/cm$. The average of a series of three measurements gave a decay rate, dN/dt = (7-25 & 0.14) x lOlo decays per minute. This result gives the following half-life for ?Sr: 0.693 N T,,, = = 29.3 i- 1.6yr. dN/dt In calculating N, the number of ?Sr into account. The yields of *%r and fission products present in the sample by the parent nucleus ssKr, the yield was found to be (5.8 f 0.4) per cent,
atoms in the sample, the efficiency of the counter was taken 90Sr in naaU fission were calculated from the known amount of (11.9 & 0.2 mg). Neglecting the possibility of neutron capture of **Sr was found to be (5.3 + 0.3) per cent. The yield of 80Sr which result includes a decay correction.
Note: In a paper by ANIKINA and ERSHLER(‘)on the determination of the Wr yield in ss*U fission, the half-life of O”Sr was taken as 19.9 years. 0) When the results of these authors are re-calculated using the half-life obtained in this work (29.3 i 1.6 years) their yield of F4r becomes (6.3 & 0.3) per cent which, within the limits of the experimental errors, agrees with the result reported here. M. P. A&A, R. N. IVANOV, G. M. KUKAVADZE,B. V. ERSHLER REFERENCES 1. PAWERSR. I. and VOIGTA. F., Phys. Rev. 79, 175 (1950). 2. HUGHESD. J. and HARVEYJ. A., Neutron Cross Sections. McGraw-Hill, New York (1955). 3. STEINBERGE. P. and GLENDENINL. E., Proceedings of the First International Conference on the Peaceful Uses of Atomic Energy, Geneva, Vol. 7., p. 3. United Nations, New York (1956). 4. KUKAVADZEG. M., ANIKINAM. P., GOL’DINL. L. and ER~HLERB. V., Conference of the U.S.S.R. Academy of Sciences on the Peaceful Uses of Atomic Energy, Moscow, Chemical Sciences Division. Consultants Bureau, New York (1955). 5. KUKAVADZEG. M., GOL’DIN L. L., ANIKINA M. P. and ERWLER B. V., Proceedings of the First International Conference on the Peaceful Uses of Atomic Energy, Geneva, Vol. 4, p. 230. United Nations, New York (1956). 6. IVANOVR. N. and KUKAVADZEG. M., Prib. tekh. eksp. 1, 106 (1957). 7. ANIIUN~ M. P. and ER~HLERB. V., J. Nucl. Energy 6, 169 (1957).