[en] Experiments using the exotic target ₆₄¹⁴⁸Gd₈₄ yielded information on the neutron single particle energies, the location and strength of the two-particle-one-hole states, and the interaction of two-particle-one-hole states with particle-coupled-to-octupole states. A source of ¹⁴⁸Gd was produced by the spallation of tantalum with 750-MeV protons at the Los Alamos Meson Physics Facility. The tantalum target was dissolved and the rare earth fractions separated from the tantalum in a hot cell. The fraction gadolinium was purified and the ¹⁴⁸Gd ions were deposited on a ∼50 μg/cm² carbon foil using the NCD-LLNL mass separator. The QDDD spectrometer at the Accelerator Laboratory of the University of Munich and Technical University of Munich was used to study the energy spectrum and angular distributions of tritons from the ¹⁴⁸Gd(d,t)¹⁴⁷Gd reaction at a deuteron beam energy of 22 MeV. The ¹⁴⁸Gd(³He,α)¹⁴⁷Gd reactions was also studied at a ³He beam energy of 30 MeV and alpha laboratory angle of 25 degrees. The QQDDQ spectrometer at the Institute of Nuclear Physics, KFA-Juelich, FRG. was used for a study of the ¹⁴⁸Gd(p,d)¹⁴⁷Gd reaction with proton beam energy of 25 MeV and at the laboratory angles of 20 degrees and 45 degrees

[en] This thesis discusses the nuclear structure of ¹⁴⁷Gd elucidated by the neutron pickup reactions (p,d), (d,t) and (³He,α) on the unstable ¹⁴⁸Gd target. The neutron pickup reaction on ¹⁴⁸Gd probes the two-particle-one-hole states by the pickup of neutrons in the shell model orbitals below the N = 82 gap and one-particle states by pickup of neutrons in shell model orbitals above the N = 82 gap. Our experiments will provide information on the location of neutron single-particle energies which can be used for shell-model calculations in the ¹⁴⁶Gd region. The 2-particle-1-hole (2p-1h) states which are probed directly by the neutron transfer reaction in the experiments with the ¹⁴⁸Gd target, will bear indirectly on the energies of one-hole states in ¹⁴⁵Gd. They will also provide information on the strongest single-particle states in ¹⁴⁷Gd because all the single-particle states in the ¹⁴⁸Gd target are partially occupied because of the mixing by the pairing interaction. 107 refs., 23 figs., 20 tabs

[en] Shell Model calculations have been carried out using a full spsdpf 2hω, model space and a PMM interaction. The neutron and alpha particle channels have been calculated and compared to our recently completed experiments for various methods of managing the strong interaction between the 0hω and 2hω states. Preliminary results with Warburton and Browns interaction will also be reported

[en] We have calibrated a self-consistent set of multigamma-ray standards using the automated multi-spectrometry γ-ray counting facility at LLNL's Nuclear Chemistry Division. Pure sources of long-lived activity were produced by mass separation and/or chemical purification. The sources were counted individually and in combination on several different calibrated spectrometer systems. These systems utilize various detectors ranging from small (x-ray) detectors to large volume high-purity Ge detectors. This has allowed the use of the most ideal individual detector-efficiency characteristics for the determination of the relative γ-ray intensities. Precise energy measurements, reported earlier (Meyer, 1976) have been performed by an independent method. Both the energy and γ-ray-emission probabilities determined compare well with independently established values such as the recent ICRM intercomparison of ¹⁵²Eu. We discuss our investigations aimed at resolving the shape of the efficiency response function up to 10 MeV for large volume Ge(Li) and high-purity Ge detectors. Recent results on the γ-ray-emission probabilities per decay for ¹⁴⁹Gd and ¹⁶⁸Tm multigamma-ray sources are discussed. For ¹⁶⁸Tm, we deduce a 0.01% β^- branch to the 87.73-keV level in ¹⁶⁸Yb rather than the previous value which was a factor of 200 greater. In addition, we describe current cooperative efforts aimed at establishing a consistent set of data for short-lived fission products. Included are recent measurements on the bromine fission products with γ rays up to 7 MeV

[en] Thin targets of radioactive ¹⁴⁸Gd were used to determine a precise value for the mass of ¹⁴⁷Gd. The (p,d), (d,t), and ³He,α) reactions were used with high-resolution charged-particle spectrometry to determine Q-values for the ¹⁴⁸Gd target relative to several calibration targets having known Q-values. By combining the measured Q-value with the ¹⁴⁸Gd mass, the mass defect, ΔM(¹⁴⁷Gd) = 75356 +- 6 keV, 149 keV less than the value in the 1977 mass tabulation was obtained. 7 refs., 1 fig., 1 tab

[en] The nuclear level density is normally addressed through the use of non-interactive fermion models. These are easy to understand, involve minimal input and are efficient for making calculations. There are some questions about the use of these models off of the stability line and in regions of extreme deformation. New developments in the theory of moment methods allow better calculations involving a two-body interaction. These techniques and some results are be presented. (orig.)

[en] In the few-MeV energy range below the (p,n) threshold, gamma rays are produced from proton bombardment of aluminum via the ²⁷Al(p,p'γ)²⁷Al, ²⁷Al(p,α,γ)²⁴Mg, and ²⁷Al(p,γ)²⁸Si reactions. Thick-target γ-ray yield data are important for various applications, including radiation shielding near accelerators and γ-ray background interference in experiments that focus on other materials. We measured p+Al γ-ray spectra over the photon energy range 0.5-15 MeV and at 0 deg. and 90 deg. laboratory angle relative to the incident proton beam. In the experiment, mono-energetic proton beams of 1.75, 2, 2.5, 3, 3.5, and 4 MeV irradiated thick stopping targets of pure aluminum. The resulting gamma rays were detected by 7.62x7.62 cm² NaI scintillation detectors. The spectra were unfolded using detector response functions calculated with the Monte Carlo code MCNP-4C. We report γ-ray spectra and tabulated γ-ray yields that can be used in applications that involve protons incident on thick aluminum targets at energies ≤4 MeV

[en] Pure sources of long-lived activity, produced by moss separation or chemical purification, have been counted individually and in combination on several different calibrated spectrometer systems. Energy and gamma ray emission probabilities were determined and compared well with existing established valves for ¹⁵²Eu. Cooperative efforts to establish a standardised set of data for short-lived fission products were discussed. (U.K.)

[en] The absolute thick target yield of 6.129, 6.917 and 7.116 MeV γ-rays produced from the ¹⁹F(p,αγ)¹⁶O source reaction has been measured for incident proton energies between 1.5 and 4.0 MeV. The angular distributions of the respective γ-lines have been determined for incident proton energies of 2.0 and 3.0 MeV. The experiments were performed at the 4.5 MV Tandem Van der Graaff accelerator at the Ohio University Edwards Accelerator Laboratory in Athens, Ohio, using a thick CaF₂ target and a 7.62 cmx7.62 cm Na(I) scintillation detector. The Monte Carlo code MCNP was used to calculate detector response functions for the three individual γ-rays. A least-squares fit of these functions to a selected region in the pulse height spectrum was carried out to determine the relative intensities of these γ-rays. The uncertainty in the fluence determination is based on the χ² of the fit, the uncertainty in the response functions, the statistics of the data, and the uncertainty in the recording of the proton charge. A maximum photon yield of 1.316x10⁷ γ/μC/sr (at 90 deg. ) was determined for the sum of these three γ-rays at the highest incident proton energy of 4.0 MeV. The contribution of the individual lines to the total photon yield depends strongly on the incident proton energy. The angular distributions are isotropic to within 15%

[en] The potential diversion of nuclear materials is a major international concern. Fissile (e.g., U, Pu) and other nuclear materials (e.g., D, Be) can be detected using 6-7 MeV gamma-rays produced in the ¹⁹F(p,αγ) ¹⁶O reaction. These gamma-rays can induce neutron emission via photoneutron and photofission processes in nuclear materials. However, they are not energetic enough to generate significant numbers of neutrons from common benign materials. Neutrons are counted using an array of BF₃ tubes in a polyethylene moderator. A strong increase in neutron count rates is seen when irradiating depleted uranium, Be, D₂O, and ⁶Li, with little or no increase for other materials (e.g., H₂O, SS, Cu, Al, C, ⁷Li). Experiments using both photon and neutron shielding show that the technique is resistant to countermeasures. We have reduced the neutron background from proton beam reactions (thus increasing the system's sensitivity) and have tested a high-current gas cell which should be capable of operating at proton beam currents of up to 100 μA