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Some radioactive isotopes of I, Xe and Cs
Wapstra, A. H., Verster, N. F.. Boelhouwer. M. 1953
Some
Physica XIX 138-139
LETTER
TO THE
radioactive
isotopes
EIlITOK
of I, Xe and Cs
Scintillation spectrometric observations have been made on some neutron deficient isotopes of Cs, and some isotopes of I decaying to the same Xe-isotopes . The following results were obtained. 7.1 day ‘32Cs. This isotope was produced by a (d, p2n) reaction on Cs, using the 26 MeV deuterons of the Philips’ synchrocyclotron in this Institute. The y-ray in this isotope was found to have an energy of 685 f 10 keV, equal to the energy reported for a y-ray in lJ21 i). Former workers 2, reported an energy 0.62 MeV. 31 h ‘29Cs. This isotope was produced together with lz7Cs, ‘2eCs and 130Cs by (u, xn) reactions on I, using the 56 MeV n-particles of the synchrocyclotron, and persisted after their decay, only mixed with a small amount of 12’Xe formed in the decay of 12’Cs. Except a y-ray of 385 keV, the conversion electrons of which were reported before 3), a much weaker (5%) y-ray of 560 keV was found to decay with this halflife. A special search was made for the 40 keV y-ray, reported in the decay of lz91 and ‘29*Xe J). It was not found; this may, however, be due to its large conversion coefficient (N 30). 5.5 h 12’Cs. Apart from a y-ray of slightly higher energy than that of ‘29Cs (410 f 20 keV) the most prominent feature in the decay of this isotope is a strong y-ray of 125 5 5 keV. This y-ray is probably identical with the second transition in the decay of the ,75 set !27Xe isomer. This indicates that G o 1 d h a b e r and H i 1 l’s “) assignment of the 93 keV electrons *) in this isomer as L conversion electrons of a 96 keV E2 y-ray may be in error, and that these electrons are K conversion electrons of a 125 keV M 1 y-ray. The groundstate of 12’Xe would then be a d3j2 state. 4 min. ‘2%~ and 25 min. ‘281. The positron annihilation peak in ‘*sCs was definitely broadened on the low energy side, indicating the presence of a y-ray with an energy slightly less than 511 keV. It seemed, however, out of the question that this energy could be as low as 428 keV, which is the energy reported 7) previously for the y-ray in 12aI. Therefore the y-ray in 12aI was remeasured; its energy is now found to be 455 f 5 keV. In addition a y-ray of 980 2 30 keV was found to be present in IzaI; its intensity is 2% of that of the 455 keV y-ray. The ratio of the intensities of the K X-radiations to the positrons in 12aCs counted by means of the annihilation radiation photopeak, is X,//7+ = = 0.4, in agreement with the ratio of K-capture to positron emission to be
-
138 -
SOME
RADIOACTIVE
ISOTOPES
OF
I,
Xe
AND
cs
139
expected 8) for an allowed pi--transition of 3 MeV “). The 455 keV y-transition occurs in about 20% of the decays; an y -ray with an energy 1.5 MeV is also found to be present. It may be added that the halflife of l**Cs appeared to be 3.9 i 0.3 min. instead of the value 3.2 min. found by former workers. We thank Prof. Dr A. H. W. A t e n and Prof. Dr C. J. Rakker for their active interest and the Foundation F.O.M. from the Organization for Pure Scientific Research Z.W.O. for their support. A. H. W.U%lRi\. N. F. VIZRST~R. M. ROELHOU\VER.
Rcwiwd
1) 2) 3) 4) 5) 6) 7) 8) 9)
20-12-52.
hl n i e II s c h c i II, 1:. C., 13 a i r, J. Ii. awl 13 a Ii c r, \\‘. I:., l’hys. Hrv. I):! (1951) 477. C a III a c, hI., see Sucker Data, Bureau of Standards Circular 499. F i n k, R. W., Re y II o I cl s, I+‘. L. and T c m p I c t on, I). l-l., l’hys. 1Zcv. ii (1950) 614. T h u 1 i n, S. and B e r g s t r ii n1 , I., Phys. licv. 85 (1952) 1055. G o 1 d h a b e r, M. and H i 1 1, 1~. D., Rev. hlod. Phys. 24 (1952) 179. C r e u t z, E. C., D e 1 s s a s o, I.. A., S u t t o II, 1~. H., \\i h i t ?, 11. (;. :UNI Barkas, W. H., Phys. Rev. 38 (1940) 481. S i c g b a h II, I<. and H o I c, S., Phys. Rev. 70 (1946) 133. F c e II b c r g, 13. and T r i g g, G., Rev. Mod. Phys. 2 (1950) 399. F i II k, R. W . ‘?nd 11’ i i h, *r E. O., .I. Am. chrm. SW. 7:) (1950) 2365.
Some
Physica XIX 138-139
LETTER
TO THE
radioactive
isotopes
EIlITOK
of I, Xe and Cs
Scintillation spectrometric observations have been made on some neutron deficient isotopes of Cs, and some isotopes of I decaying to the same Xe-isotopes . The following results were obtained. 7.1 day ‘32Cs. This isotope was produced by a (d, p2n) reaction on Cs, using the 26 MeV deuterons of the Philips’ synchrocyclotron in this Institute. The y-ray in this isotope was found to have an energy of 685 f 10 keV, equal to the energy reported for a y-ray in lJ21 i). Former workers 2, reported an energy 0.62 MeV. 31 h ‘29Cs. This isotope was produced together with lz7Cs, ‘2eCs and 130Cs by (u, xn) reactions on I, using the 56 MeV n-particles of the synchrocyclotron, and persisted after their decay, only mixed with a small amount of 12’Xe formed in the decay of 12’Cs. Except a y-ray of 385 keV, the conversion electrons of which were reported before 3), a much weaker (5%) y-ray of 560 keV was found to decay with this halflife. A special search was made for the 40 keV y-ray, reported in the decay of lz91 and ‘29*Xe J). It was not found; this may, however, be due to its large conversion coefficient (N 30). 5.5 h 12’Cs. Apart from a y-ray of slightly higher energy than that of ‘29Cs (410 f 20 keV) the most prominent feature in the decay of this isotope is a strong y-ray of 125 5 5 keV. This y-ray is probably identical with the second transition in the decay of the ,75 set !27Xe isomer. This indicates that G o 1 d h a b e r and H i 1 l’s “) assignment of the 93 keV electrons *) in this isomer as L conversion electrons of a 96 keV E2 y-ray may be in error, and that these electrons are K conversion electrons of a 125 keV M 1 y-ray. The groundstate of 12’Xe would then be a d3j2 state. 4 min. ‘2%~ and 25 min. ‘281. The positron annihilation peak in ‘*sCs was definitely broadened on the low energy side, indicating the presence of a y-ray with an energy slightly less than 511 keV. It seemed, however, out of the question that this energy could be as low as 428 keV, which is the energy reported 7) previously for the y-ray in 12aI. Therefore the y-ray in 12aI was remeasured; its energy is now found to be 455 f 5 keV. In addition a y-ray of 980 2 30 keV was found to be present in IzaI; its intensity is 2% of that of the 455 keV y-ray. The ratio of the intensities of the K X-radiations to the positrons in 12aCs counted by means of the annihilation radiation photopeak, is X,//7+ = = 0.4, in agreement with the ratio of K-capture to positron emission to be
-
138 -
SOME
RADIOACTIVE
ISOTOPES
OF
I,
Xe
AND
cs
139
expected 8) for an allowed pi--transition of 3 MeV “). The 455 keV y-transition occurs in about 20% of the decays; an y -ray with an energy 1.5 MeV is also found to be present. It may be added that the halflife of l**Cs appeared to be 3.9 i 0.3 min. instead of the value 3.2 min. found by former workers. We thank Prof. Dr A. H. W. A t e n and Prof. Dr C. J. Rakker for their active interest and the Foundation F.O.M. from the Organization for Pure Scientific Research Z.W.O. for their support. A. H. W.U%lRi\. N. F. VIZRST~R. M. ROELHOU\VER.
Rcwiwd
1) 2) 3) 4) 5) 6) 7) 8) 9)
20-12-52.
hl n i e II s c h c i II, 1:. C., 13 a i r, J. Ii. awl 13 a Ii c r, \\‘. I:., l’hys. Hrv. I):! (1951) 477. C a III a c, hI., see Sucker Data, Bureau of Standards Circular 499. F i n k, R. W., Re y II o I cl s, I+‘. L. and T c m p I c t on, I). l-l., l’hys. 1Zcv. ii (1950) 614. T h u 1 i n, S. and B e r g s t r ii n1 , I., Phys. licv. 85 (1952) 1055. G o 1 d h a b e r, M. and H i 1 1, 1~. D., Rev. hlod. Phys. 24 (1952) 179. C r e u t z, E. C., D e 1 s s a s o, I.. A., S u t t o II, 1~. H., \\i h i t ?, 11. (;. :UNI Barkas, W. H., Phys. Rev. 38 (1940) 481. S i c g b a h II, I<. and H o I c, S., Phys. Rev. 70 (1946) 133. F c e II b c r g, 13. and T r i g g, G., Rev. Mod. Phys. 2 (1950) 399. F i II k, R. W . ‘?nd 11’ i i h, *r E. O., .I. Am. chrm. SW. 7:) (1950) 2365.