Charles D. Coryell

The γ-ray spectrum of short-lived fission-product bromine isotopes and the decay scheme of 3·0-min 85Br

Abstract By observing the γ-ray spectra of short-lived bromine species separated from fission products at different times after irradiation, it was possible to differentiate between some of the γ-rays belonging to the decay of 54 sec 86 Br and 55 sec 87 Br. Three γ-rays of 801·6, 832·0, and 925·1 keV were found to decay with a 3·0 min half-life and they are assigned to the decay of 3·0 min 85 Br. Together with the results of nuclear excitation studies in 85 Kr, a decay scheme is constructed for 85 Br, with levels in 85 Kr at 305, 1106·6, 1137·0, and 1230·1 keV.

Half life of 135Sb and evidence on the half life of 134Sb

Abstract A search for delayed-neutron precursors among the short-lived antimony fission products was unsuccessful. This result suggested that either (1) the neutron branching of the possible precursors 134 Sb and 135 Sb is extremely small or (2) that the half lives of those isotopes are much shorter than the upper limits previously reported (45 and 24 sec, respectively). Results of milking experiments in which iodine activity grown from antimony samples separated quickly after neutron irradiations of uranium was counted give the half life of 135 Sb as 1·9 −0·5 +0·9 sec and an upper limit of 1·5 sec for that of 134 Sb. It is suggested that the ∼ 45 sec antimony fission product, previously ascribed to 134 Sb or 135 Sb, may be an isomer of 132 Sb.

Identification and characterization of 3.8 min 134mI

Abstract The γ -ray spectra of iodine fractions rapidly separated from the products of slow neutron fission of 235 U were studied. A 3.8 ± 0.2 min species was found and was identified as 134m I from observations of corresponding growth in the intensities of the prominent 847 and 884 keV γ-rays of 53 min 134 I. This isomer is analogous to the 2.9 h isomer 134m Cs and decays by the sequence 134m I ( J π = 8 − )( J π = 5 + ) 134 I ( J π = 4 + ) by transitions of 271.9 ± 0.2 keV (t 1 2 = 3.8 min ; α k and 44.4 ± 0.1 keV( t 1 2 ns ; α k ), respectively. For a 316 keV cross-over γ-ray an upper limit of 1 % was obtained, and is near the intensity predicted by M4 systematics. A low-intensity γ-ray of 234.3 ± 0.5 keV was found This γ-ray is interpreted as evidence for β-decay (2%) of the isomer, possibly to the 0.29 sec 7 − isomeric level in 134 Xe.

Decay of 45 sec and 83 sec 136I isomers

Abstract The γ-ray spectra of iodine species rapidly isolated from fission have been studied using Ge(Li) and NaI(Tl) detectors and 4096 channel analyzers. A total of 17 γ-rays are attributed to the decay of 83 sec 136I. Another species was observed which decayed with 45 sec half-life by emission of 197·3, 220, 370, 381·8, and 1313·3 keV γ-rays. The 1313·3 keV γ-ray, previously attributed only to the decay of 83 sec 136I, was found to have a 45 sec component. This observation characterizes the 45 sec species as an isomer of 136I. A decay scheme is constructed for 45 sec 136I with levels at 1313·3, 1694·1, 1892·4, and 2262·4 keV. A partial decay scheme is proposed for 83 sec 136I. The nature of the levels is discussed and the results are compared with those from previous decay scheme and nuclear excitation studies.

The neutron activation of chlorates and perchlorates and the preparation of 38ClO3− and 38ClO4−

Abstract Conditions were studied for the preparation of chlorate and perchlorate ions tagged with 37 min 38 Cl tracer. Neutron activation of alkali chlorates gives about 5 per cent of the 38 Cl as 38 ClO 3 − and no appreciable amount as 38 ClO 4 − ; activation of the perchlorates gives about 14 per cent of the 38 Cl as 38 ClO 3 − but only negligible amounts as 38 ClO 4 − . Heat treatment of neutron activated NaClO 4 or KClO 4 for 20 minutes at 500°C gives about 10 per cent of the total 38 Cl as 38 ClO 4 − . Anodic oxidation of chloride and oxidation by argentic ion are not promising for the production of tagged perchlorate ion but the latter process can be to prepare tagged chlorate. Separation and identification of chloride, chlorate and perchlorate are accomplished by selective elution by nitrate ion from an anion-exchanger column (order of appearance, Cl − , ClO 3 − and ClO 4 − ). Procedures are given for the preparation of 38 ClO 3 − free of appreciable bulk chlorate or other oxidation states of chlorine, and for milligram amounts of perchlorate tagged with 38 ClO 4 − , free of other oxidation states of chlorine.

Radiations from 83 min 139Ba

Abstract The decay scheme 83 min 139 Ba has been examined by detailed γ-scintillation spectroscopy. The energies of the γ-rays in MeV and their relative intensities are 0·165 (100), 1·092 ± 0·015 (0·12), 1·272 ± 0·012 (0·30), and 1·433 ± 0·008 (1·8). The second and third are new, and have been corroborated in an independent study of Bunker and Starner . No evidence was found for the γ-ray of 0·78 MeV reported by Jastrzebski . Fig. 2 incorporates the results in a decay scheme, in which the absolute yield of the 0·165 MeV level of Macklin , et al. has been used to calculate the β-group intensities.

The Hammett acidity function H0 in H2SO4SO3 mixtures; superacidity

Abstract The comparative quantitative acidities of mineral acids H + (ClO 4 − ) and H + (HSO 4 − ), the two superacids, then HI, HBr, HCl, HNO 3 , Cl 3 CCOOH, and HF are reviewed in the light of the Hammett and Michaelis acidity functions H 0 and G . The great power of the Hammett quantitative acidity function H 0 is emphasized, with evidence being provided for the independence of charge in Hammett general acidity function H x with charge type of the indicator in concentrated water-type solutions. The Lewis-Bigeleisen extension of the Hammett function H 0 to H 2 SO 4 SO 3 mixtures, using vapour pressure of SO 3 as a measure of H 0 , is reviewed, and an error separating H 0 from −log α H + is removed. The Lewis-Bigeleisen data provide by this interpretation new information on the polyacids H 2 O(SO 3 ) n , and the superacid anhydrous SO 3 . The effective proton activity of anhydrous SO 3 is given as 10 14·1 referred to that in 1 M H 3 O + and unity.

Isomeric-yield ratios of 117Cd in the (n, γ) and (d, p) reactions

Abstract An isomeric-yield ratio, σ m σ g = 0·24±0·03 , was determined for the production of 2·4- h 117 g Cd and 3·4-h 117m Cd in the ( n , γ) reaction by measuring the relative intensities of γ-rays of the 117 Cd isomers and also of the 38-m 117g In and 1·93-h 117m In daughters milked from the 117 Cd. In the ( d , p ) reaction, the isomeric yield-ratio was found to be 0·60 ± 0·08. The reason for these ratios to be higher in 117 Cd than in 115 Cd is discussed in terms of the possibility of inversion of the level position of a low-lying 5 2 state with respect to that of a neighboring 7 2 or 9 2 state in going from 115 Cd to 117 Cd. The lowering of a 7 2 or 9 2 state below the 5 2 state in 117 Cd afford an intermediate state to channel transitions from the 5 2 states to the 11 2 −117m Cd , thus raising the isomer ratio.