Thermal Neutron Activation Cross Section Research Articles

Production of cationic 198Au3+ and nonionic 198Au0 for radionuclide therapy applications via the natAu(n,γ)198Au reaction

198Au (βmax = 0.96 MeV (98.6 %), γmax = 0.412 MeV (95.5 %) and T1/2 = 2.7 days) is a radionuclide with very appealing characteristics. 198Au has been widely used to treat the uterus, bladder, cervix, prostate, melanoma, breast, skin and other cancers. In the present study, cationic 198Au+3 and nonionic 198Au0 are prepared following thermal neutron irradiation of commercially available natural gold compounds in Tehran Research Reactor via the natAu(n,γ)198Au reaction. The prospects in the production of pure 198Au0 and 198Au+3 for radionuclide therapy are discussed and effect of reduction on the activity of radioactive gold is evaluated. Au0 particles were synthesized via NaBH4 reduction of aqueous solutions of hydrogen tetrachloroaurate trihydrate. Then two quartz tubes were charged with cationic 198Au3+ and nonionic 198Au0. After irradiation by thermal neutrons, the samples were analyzed for a period of 1 month by liquid scintillation counter and high purity germanium detector. As a result, natAu3+ reduction process had no significant effect on the activity of the 198Au sample. In conclusions, natural gold thermal neutron activation cross section is reasonably high for medical application.

Calibration of the fission-track dating method: Is Cu useful as an absolute thermal neutron fluence monitor?

Thermal neutron fluence measurements have been performed with Au and Co standard monitors at the one side and Cu monitors (foils and wires) at the other. using three reactor channels with different neutron energy spectra and two calibrated Ge detectors. Care was taken to eliminate errors caused by epithermal activation and neutron self-shielding while special attention was also paid to the problem of incomplete annihilation of the 64Cu β + radiation. Our new measurements reveal consistent fluences between Cu and the Au and Co standard monitors, when using the recommended and/or recently evaluated nuclear parameters for the 63Cu(n,γ) 64Cu reaction. However, we do not endorse the usage of Cu as a standard fluence monitor for fission-track dating because from a metrological standpoint too large uncertainties still exist on some of its relevant nuclear parameters such as the thermal neutron activation cross-section ( σ 0) of 63Cu.

Neutron activation cross-section of zirconium-94

The thermal neutron activation cross-section of94Zr was found to be 49.3±0.6 millibarns. It is shown that neutron activation analysis of Zr in silicate samples with a Zr/U ratio<10 has considerable uncertainty due to fission contribution. A correction factor for the fission contribution has been determined experimentally.

Determination of uranium, antimony, indium, bromine and cobalt in atmospheric aerosols using epithermal neutron activation and a low-energy photon detector

Owing to the high ratio of resonance integral to thermal neutron activation cross-section of238U, a 5 min epithermal neutron irradiation under cadmium shielding, followed by measurement of the 74 keV photopeak of239U with a high resolution low-energy photon Ge(Li) detector, allows the fast determination of uranium in aerosols collected on a Whatman 41 cellulose filter. Uranium blanks of the cellulose filter paper require correction and limit the sensitivity. Simultaneously the concentrations of the elements cobalt, bromine, antimony and indium can be determined. In Belgium, the uranium concentrations of the aerosols were found to be constant and comparable to the uranium contents of rocks.

Resonance activation integrals of some lanthanide nuclides

The resonance activation integrals were determined for the following nuclides: 139La, 148Nd, 150Nd, 151Eu, 158Gd, 164Dy, 165Ho, 176Er, 176Yb and 175Lu. The determinations were based on cadmium ratio measurements and known values for the thermal neutron activation cross-sections. Small samples of 197Au( σ 0 = 98·8 b, I 0 = 1550 b) were used as flux monitors.

Thermal Neutron Activation Cross Sections and Resonance Integrals of 94Zr and 96Zr

The activation method was used to determine thermal neutron activation cross sections, σ0, and resonance integrals, RI. Values obtained were σ0 = 47.5 ± 2.4 mb, RI = 218 ± 10 mb for 94Zr and σ0 = 22.9 ± 1.0 mb, RI = 5.20 ± 0.54 b for 96Zr. Calculations were based on the Westcott convention and the known cross sections for the 59Co and 197Au neutron flux monitors. Measurements confirmed the existence of a p-wave neutron resonance capture for 96Zr. The half-life of 97Zr was measured as 16.90 ± 0.05 h.

Resonance activation integrals of some nuclides of interest in neutron activation analysis

The following previously-unreported resonance activation integrals I 0 were determined: 46Ca, 0·32±0·12b; 84Sr, 10·6±1·1b; 130Ba, 270±70b; 152Gd, 3000±300b; 158Gd, 84±20b. In addition, I 0 values for 21 nuclides were redetermined. The determinations were based on cadmium ratio measurements and on known values for the thermal neutron activation cross-sections. Small samples of 197Au ( σ 0 = 98·8b; I 0 = 1550b) were used as flux monitors. The thermal neutron activation cross-section for 152Gd was found to be 1100±100b.

Reactor neutron activation analysis by a triple comparator method

The single comparator method has been extended to a triple comparator method, using60Co,114m In and198Au. In this technique, thek-ratios of the elements to be analyzed, now determined against the three comparators, are corrected for each new ratio of thermal to epithermal reactor neutron flux. These flux ratios are calculated from the absolute activities of the three comparators. The thermal neutron activation cross-section and the resonance integral for the reaction113In(n,γ)114m In have been determined.

Thermal and 14.4 MeV neutron activation cross sections of argon

Thermal and 14.4 MeV neutron activation cross sections of argon were measured with argon quinol-clathrate powder as target material. The thermal neutron activation cross section of the 40Ar(n, γ) 41Ar reaction was measured to be 510±25 mb. The 14.4±0.3 MeV neutron activation cross sections for the reactions 38Ar(n,p) 38Cl, 40Ar(n,p) 40Cl(1.4 min), 40Ar (n, np+n, pn+n, d) 39Cl and 40Ar(n, α) 37S were measured to be 75±20, 15.7±2.0, 1.40±0.15 and 10.5±1.0 mb, respectively. These values are compared with prior measurements and with semi-empirical predictions of Levkovskii and of Gardner.

Thermal neutron activation cross sections for Kr and Xe isotopes

Quinol-clathrates of Kr and Xe have been used as solid targets for neutron activation for the first time, and 16 (n, γ) cross sections have been determined with thermal neutrons. The epithermal neutron contribution has been taken into account by irradiating Cd covered samples. Four isomer cross-section ratios for Xe isotopes and one for Kr have also been obtained. In the case of Xe isotopes, the spin cut-off parameters are evaluated from the isomer ratios.

Thermal neutron activation cross sections for the isomeric states in odd indium isotopes and the j-selection rule

The thermal neutron activation cross sections for the two isomeric states in 114In were measured using a 2π flow counter for the long-lived and the pulsed activation method for the short-lived isomer. The values obtained are σ act = 7.5±0.7 b for 114 m 1 In (49 d) in agreement with a value measured by Keisch, and σ act = 3.1 −0.7 +0.4 b for 114m 2In (42 msec). The isomeric cross-section ratios were analysed using the statistical approach of Huizenga and Vandenbosch. It follows that both isomeric states should have the same spin value 5, in spite of the fact that they are connected by a pure E3 transition. The same situation prevails in 116In. Possible explanations are (i) E1 and M2 transitions are so strongly hindered that they are in fact completely suppressed; and (ii) the statistical approach in evaluating isomeric cross-section ratios breaks gamma-ray down because of the channellizing action of the ( g 9 2 −1) p ( h 11 2 ) n multiplet which directs the gamma-ray cascade to its member with the lowest excitation energy (i.e. the isomeric state). Both explanations are founded on the action of the j-selection rule, which forbids transitions of low multipole order between the configurations [( g 9 2 −1) p( h 11 2 ) n]1 − … 10 − and [( g 9 2 −1) p( S 1 2 + d 3 2 ) n] 4 +, 5 + .

Thermal Neutron Activation Cross Section of 116Cd for the Production of the 117Cd Isomers

Thermal Neutron Activation Cross Section of ¹¹⁶Cd for the Production of the ¹¹⁷Cd Isomers

Ein neues isomer des Lu 177 MIT 160 μsec Halbwertszeit

By activation of lutetium in a pulsed thermal neutron beam two delayed coincident γ-rays of 110±3 keV and 460±5 keV have been found. An isomeric state with a half life of 160±10 μsec has been assigned to Lu 177 using recently published precise capture γ-ray measurements of Maier. From the intensity ratio of X- and γ-rays it is concluded that the 110 keV transition is a E2 transition. The isomeric level at 570 keV excitation energy can be identified with the Nilsson orbital 1 2 + [411] which decays by hindered E2 radiation to the base state of the 5 2 + [402] band followed by M1 radiation to the ground state. The construction of a 1 2 + [411] rotational band has been attempted. The value of the thermal neutron activation cross section for the isomeric state in Lu 177 is: σ Lu177 m3 = 315± 60 b.

A new isomer of bromine: 82 mBr

The decays of 82 m Br have been studied by γ-ray scintillation spectroscopy and a beta proportional counter. This new isomer was observed to decay with a half-life of 6·20 ± 0·05 min, exciting a highly converted γ-ray transition in 82Br of 46 ± 2 keV. α K is 268. A total combined beta branching of 2·4 per cent was also observed. The thermal neutron activation cross section and resonance integral for 82 m Br are 3·0 and 34 barns, respectively, and the corresponding values for the total production of 82Br are 3·23 ± 0·2 and 41·3 ± 1 barns.

The Ar 40 thermal activation cross-section and resonance integral

The Ar 40(n, γ)Ar 41 thermal neutron activation cross section has been determined to be 0.723±0.025 b, utilizing both Au ( σ 0=98.4±0.5) and Co ( σ 0=37.7±0.7 b) as reference standards. This value is 26% higher than the normally accepted activation cross section of 0.53 b and is 14% higher than the weighted mean elemental absorption cross section of 0.62 b. The resonance capture integral above 0.5 eV, which has not previously been measured, was found to be 0.41±0.03 b relative to 1534 b to Au 197. The Westcott temperature-independent resonance parameter s 0 was found to be 0.217±0.010.

Thermal Neutron Activation: Measurement of Cross Section for Manganese-53

The product of the thermal neutron activation cross section and half-life for manganese-53 is (350 +/- 100) x 10(6) barn-years. If a value of 2 x 10(6) years is assumed for the half-life of manganese-53, then the cross section is 170 barns. This large cross section affords much greater sensitivity for the determination of manganese-53.

IsomerRe188m

Two new transitions in ${\mathrm{Re}}^{188m}$ were found which are responsible for the 18.7-min half-life of this isomer. The energies and branching ratios of these transitions which originate from a 6-state at 171.9 keV, are 2.4 keV (57%) and 15.9 keV (43%). Their multipole orders are $M3$. Each transition is followed by an $M1$ transition, 105.9 and 92.4 keV, respectively, both terminating in the first excited (2-) state at 63.58 keV, which decays by an $M1$ transition to the ground state. The ground state and the first two excited states appear to be members of a rotational band with $K=1\ensuremath{-}$, whereas the 3rd and 4th excited states can be interpreted as composed of the same proton orbit as that of the ground state, but of different neutron orbits. The thermal neutron activation cross section of ${\mathrm{Re}}^{187}$ leading to the isomer was found to be 1.25\ifmmode\pm\else\textpm\fi{}0.25 b.

Thermal Activation Cross Sections and Resonance Integrals of In115

New measurements of the thermal neutron activation cross sections and the resonance activation integrals (14 sec and 54 min activity) of In115 are described. The results are discussed and compared with those of other recent determinations.

Thermal neutron activation cross-sections for isomer production (II)

Thermal neutron activation cross-sections have been measured for the following cases: Hg 196(n, γ)Hg 197m(130±12% b); Hg 196(n, γ)Hg 197(2936±15% b); Pt 194(n, γ)Pt 195m(< 200 mb); Pt 192(n, γ)Pt 193m(70±20% b); Os 190(n, γ)Os 191m(8.55±18% b); Os 190(n, γ)Os 191(3.9±20% b); Er 170(n, γ)Er 171(4.3±15% b); Pd 110(n, γ)Pd 111m(37±15% mb); Gd 158(n, γ)Gd 159(2780±18% mb); Gd 160(n, γ)Gd 161(768±15% mb); Ba 134(n, γ)Ba 135m(158±15% mb); Ba 132(n, γ)Ba 133m(< 150 mb); Sn 122(n, γ)Sn 123(206±15% mb); Sn 124(n, γ)Sn 125(125±15% mb) Using the spin distribution form due to Beths 1) and Block 2) theoretically calculated isomeric ratios have been compared with experimentally measured values.

Thermal neutron activation cross-sections for isomer production

Abstract Thermal neutron activation cross-sections for the following cases have been measured by making irradiation with the “Swimming pool” reactor at Trombay, Bombay with the following results: • Pt 196 (n, γ )Pt 197m (69±20% mb); • W 184 (n, γ )W 185 m(22±20% mb); • Te 130 (n, γ )Te 131 (161±15% mb); • Te 126 (n, γ )Te 127 (1034±15% mb); • Cd 108 (n, γ )Cd 109 (1410±25% mb); • Zn 70 (n, γ )(9±20% mb); • Zn 68 (n, γ )(83±15% mb); • Os 189 (n, γ )Os 190m (8±25% mb); • Dy 164 (n, γ )Dy 165 (951±25% b); • Te 128 (n, γ )Te 129 (178±15% mb); • Cd 16 (n, γ )Cd 117 ( • Cd 110 (n, γ )Cd 111m (132±15% mb); • Zn 70 (n, γ )Zn 71 (111±20% mb); • Zn 68 (n, γ )Zn 69 (116±15% mb); The activation method was employed for these measurements.