[en] A study of the beta decays of ¹²⁶Cd and ¹²⁶In using the TRISTAN on-line isotope separator facility is reported. Gamma-ray singles measurements were made for both decays usng Ge(Li) and LEPS (low energy photon spectrometer) detectors. In addition, gamma--gamma coincidence measurements and gamma multiscale measurements were made for both decays using Ge(Li) detectors. The half-life for ¹²⁶Cd was determined to be 0.506 +- 0.015 sec., and the half-lives for the low- and high-spin ¹²⁶In isomers were determined to be 1.83 +- 0.11 sec. and 1.96 +- 0.10 sec., respectively. A total of 11 gamma rays were observed in the decay of ¹²⁶Cd, and all but one were placed in a level scheme for ¹²⁶In. A total of 48 gamma rays were observed in the decay of the low- and high-spin ¹²⁶In isomers and all were placed in a level scheme for ¹²⁶Sn. Spin and parity assignments were deduced, whenever possible, on the basis of logft values and gamma decay selection rules. The ¹²⁶In decay schemes (one has been proposed for each isomer) are compared with earlier decay studies and with results from ¹²⁴Sn(t,p)¹²⁶Sn reaction experiments. The systematics associated with the level schemes are discussed and a comparison is made with the nuclear shell model. 49 references

[en] A study of the beta decays of ¹²⁶Cd and ¹²⁶In at the TRISTAN on-line isotope separator facility is reported. Gamma-ray singles measurements were made for both decays using Ge(Li) and LEPS (low-energy photon spectrometer) detectors. In addition, gamma-gamma coincidence measurements and gamma multiscale measurements were made for both decays by means of Ge(Li) detectors. The half-life for ¹²⁶Cd was determined to be 0.506 +- 0.015 s, and the half-lives for the low- and high-spin ¹²⁶In isomers were determined to be 1.83 +- 0.11 s and 1.96 +- 0.10 s, respectively. A total of 11 gamma rays were observed in the decay of ¹²⁶Cd, and all but one were placed in a level scheme for ¹²⁶In. A total of 48 gamma rays were observed in the decay of the low- and high-spin ¹²⁶In isomers, and all were placed in a level scheme for ¹²⁶Sn. Spin and parity assignments were deduced, whenever possible, on the basis of logft values and gamma decay selection rules. The ¹²⁶In decay schemes (one has been proposed for each isomer) are compared with earlier decay studies and with results from ¹²⁴Sn(t,p)¹²⁶Sn reaction experiments. The systematics associated with the level schemes are discussed, and a comparison is made with the nuclear shell model

[en] Determination of response characteristics is an important phase in the development of a logging tool. Accurate computer simulations of the response can save a considerable amount of time and money: constructing model formations and tool prototypes is a very costly process. Contained in this paper is a description of a technique that can be used to perform accurate response simulations for a particular class of well logging tool. This group of instruments may be categorized as spectral gamma-ray tools and includes those tools that are used to analyze photons incident from the formation. Examples illustrate the application of this method to a particular type of spectral gamma-ray tool, that which is used to record photons induced by inelastic scattering and neutron absorption reactions in the formation

[en] Sample deuteron spectra and extensive angular distributions (with DW fits) from these reactions at 26.2 MeV are presented. States excited in these reactions, along with l-transfer and J/sup π/, are tabulated and briefly discussed. 12 figures, 2 tables

[en] Logging tools that record the entire natural gamma ray spectrum are designed to measure concentrations of the naturally occurring radioactive elements Potassium (K), Uranium (U), and Thorium (Th). A sophisticated mathematical method is used to compute the calibration spectrum for each of the tracer elements in a range of environments. The Boltzmann transport equation is solved for the gamma ray flux at the detector surface and convolved with a detector response function determined by Monte Carlo simulation to obtain the spectra. Once properly calibrated, a spectral stripping technique computes quantitative concentrations for all radioactive isotopes in the formation. Techniques for utilization of these concentrations is discussed. Several log interpretation examples illustrate the discussion

[en] The effectiveness of a new resolution enhancement method for compensated neutron porosity logs is illustrated. The new method is the same as conventional ratio processing except that a smaller amount of depth shifting is used. Simulated log data is used to show that this method increases the vertical resolution by a factor of two: the vertical resolution obtained with conventional processing is about 2 1/2 feet; with the new method the vertical resolution is approximately 1 foot. This method is compared with a resolution enhancement proposed previously in which the log response is sharpened by obtaining the porosity from the near detector count rate instead of the ratio between near and far detector count rates. The new method produces similar results but is simpler to implement

[en] The impact of detector choice on the elemental variance in the yields for capture gamma-ray spectrometry is studied assuming identical external environments and neutron source output. The trade-off between lower sensitivity but moderate resolution detectors such as NaI and CsI with the higher sensitivity but lower resolution detectors such as GSO (gadolinium silicate) and BGO (bismuth germinate) is quantitatively assessed. Several common well logging environments are modeled with the Monte-Carlo code MCNP and convolved with detector response maps for each detector type. The elemental standards for the environmental cases are computed and the standard weighted-least-squares fitting procedure is applied. Five elements (H, Si, Ca, Cl and Fe) are assumed present. The variance-covariance matrix from this procedure provides the uncertainty in the elemental yields. Laboratory results obtained using a BGO detector benchmarked the modeling

[en] A method for simulating the pulse height responses of passive gamma ray spectroscopy logging tools is described and its application to measurements of radioactive tracer spectra is demonstrated. Comparison of simulated and measured calibration spectra for several tracers illustrates the accuracy and utility of the method which is now being used to extend the applications to additional tracer isotopes and other wellbore geometries

No abstract available

[en] The decay scheme of neutron-rich ¹²⁶Cd is reported for the first time. Sources of mass-separated ¹²⁶Cd were produced using an in-beam target ion source combination. The ¹²⁶Cd half-life was measured to be 0.506 +- 0.015 sec. Of 11 γ rays observed, 10 were placed in a ¹²⁶In level scheme consisting of 6 excited states at 260, 308, 555, 585, 626, and 688 keV. The level density of low-spin excited states is less than that for ¹²⁴In, and most of our levels are describable in terms of a single proton hole coupled to a single neutron hole. Surprisingly, most of the β strength feeds one level in ¹²⁶In at 688 keV