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We have studied the properties of the unbound isotope of helium 7He, using the 2H(8Li,3He)7He reaction. When combined with prior measurements of the 2H(6He,p)7He reaction the data present a consistent picture for the low-lying excited states of 7He, specifically the negative parity sequence 3/2- (ground state) 1/2- (first-excited) and 5/2- (second-excited). The shapes but not the absolute magnitudes of the angular distributions are reproduced by ab-initio theory coupled with a DWBA reaction framework. [ABSTRACT FROM AUTHOR]

The 12C(α,γ)16O reaction is of great importance for the understanding the nuclear synthesis and explosion mechanism of the supernova. The cross section at the relevant stellar burning energies, around 300 keV, is dominated by the sub-threshold resonances. The 16N β-delayed α decay data provide the most sensitive constrain on this sub-threshold resonance. Using twin-ionization chambers, we have measured the α particles and 12C recoil nuclei in coincidence. The spectrum has been fitted together with the published 12C(α,γ)16O data and the elastic scattering phase shift data using R-matrix. The SE1 factor at 300 keV has been determined as 73±21 keVb. [ABSTRACT FROM AUTHOR]

Single-neutron transfer with the (d,p) reaction in inverse kinematics has been used to study the properties of the light nuclei 9Li and 7He. The results for 9Li and 7Heg.s. are compared to the predictions of ab-initio models of nuclear structure. Different possibilities for excited states in 7He are discussed in the context of other recent experimental studies of 7He. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

Coulomb excitation of Kπ=6+(t1/2=77 ns), 8-(t1/2=4.0 s) and 16+(t1/2=31 y) 178Hf isomers has led to the measurement of a set of Eλ matrix elements, coupling the isomer bands to the γ- and ground state bands. The resulting matrix elements, derived using a coupled-channel semiclassical Coulomb excitation search code, have been used to probe the K-components in the wave functions and revealed the onset and saturation of K-mixing in low-K bands, whereas K-mixing is negligible in the high-K bands. The implications can be applied to other quadrupole-deformed nuclei. An upper limit on the Coulomb depopulation yield of the 16+ isomer was calculated based on the present set of matrix elements. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

The quasi-continuum of γ rays from the feeding and decay of superdeformed and normal bands in the nucleus 152Dy have been extracted in 1 - and 2 - dimensional spectra. The Eγ-Eγ correlations in the latter reveals strong ridges associated with superdeformed and normal states in this nucleus. The entry distributions for normal and superdeformed bands were also extracted. A Monte Carlo model was developed that simultaneously describes all the quasi-continuum and ridge spectra as well as the feeding intensity of the superdeformed bands. Through the calculation of the continuum of γ rays at finite temperature, the rotational damping widths in the normal and superdeformed wells were extracted. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

We report on the status of a combined experimental and modeling study for atomic layer deposition (ALD) of HfO2 and Al2O3. Hafnium oxide films were deposited from tetrakis(dimethylamino)hafnium and water. Aluminum oxide films from trimethyl aluminum and water are being studied through simulations. In this work, both in situ metrologies and process models are being developed. Optically-accessible ALD reactors have been constructed for in situ, high-sensitivity Raman and infrared absorption spectroscopic measurements to monitor gas phase and surface species. A numerical model using computational fluid dynamics codes has been developed to simulate the gas flow and temperature profiles in the experimental reactor. Detailed chemical kinetic models are being developed with assistance from quantum chemical calculations to explore reaction pathways and energetics. This chemistry is then incorporated into the overall reactor models. © 2005 American Institute of Physics [ABSTRACT FROM AUTHOR]

We have studied the properties of low-lying levels in 7He using the d(6He,p)7He reaction. Recent measurements of 8He breakup and the p(8He,d)7He reaction present conflicting results on 7He first excited state A broad resonance observed in the present work at EX = 2.2-0.1+0.2 MeV is identified with the expected 1/2- spin-orbit partner to the 7He ground state. No evidence is seen of a lower first-excited state that was recently reported. © 2005 American Institute of Physics [ABSTRACT FROM AUTHOR]

Two Gammasphere experiments have been performed in order to establish the possible triaxial nature of strongly deformed (SD) bands in 174Hf. A lifetime measurement confirmed the large deformation of the four previously observed bands in this nucleus. In addition, a thin-target, high-statistics experiment was carried out to search for linking transitions between the SD bands. No such transitions, which represent an experimental signature for wobbling modes, were observed. Four new SD bands were found in 174Hf together with a single SD band in 173Hf. These results indicate that the strongly deformed sequences of N ≈ 102 Hf isotopes behave differently than the TSD bands found in Lu nuclei near N = 92. The interpretation of these bands in terms of possible stable triaxial deformation is confronted with the experimental findings and UC predictions. © 2005 American Institute of Physics [ABSTRACT FROM AUTHOR]

Both the quasi-continuum of γ rays as well as the ridges from the feeding (and decay) of superdeformed and normal bands have been extracted in the nucleus 152Dy. A model has been developed that simultaneously describes all these spectra as well as the feeding intensity of the superdeformed bands. Through the calculation of the continuum of γ rays at finite temperature, the rotational damping width in the normal and superdeformed wells are extracted. This is the first time the rotational damping width in a superdeformed well has been measured in the A∼150 mass region. © 2005 American Institute of Physics [ABSTRACT FROM AUTHOR]

The level structure of 249Bk has been investigated by measuring the γ-ray spectra following the α decay of a chemically and isotopically pure 253Es sample. Alpha-gamma coincidence measurement was performed using a Si detector for α particles and a 25% Ge detector for γ rays. A gamma-gamma coincidence measurement was performed with the Gammasphere spectrometer. The Es sample was obtained by extracting the 253Es which grew in a 253Cf source material produced in the High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory. Additional information on the 249Bk levels was obtained from the study of γ rays produced in the β- decay of 249Cm. The 249Cm sample was produced by neutron irradiation of 248Cm. Using the results of the present study and the results of previous 248Cm(α,t) and 248Cm(3He,d) reaction spectra, the following single-particle states have been identified in 249Bk: 7/2+[633], 0.0 keV; 3/2-[521], 8.78 keV; 1/2+[400], 377.55 keV: 5/2+[642], 389.17 keV; 1/2-[530], 569.19 keV; 1/2-[521], 643.0 keV; 5/2-[523], 672.8 keV; 9/2+[624], 1075.1 keV. Four vibrational bands were identified at 767.9, 932.2, 1150.7 and 1223.0 keV with tentative assignments of {7/2+[633]x1-}9/2-, {7/2+[633]x0-}7/2-, {7/2+[633]x1-}5/2- and {7/2+[633]x0+}7/2+, respectively. © 2005 American Institute of Physics [ABSTRACT FROM AUTHOR]

An 85 mm × 85 mm × 20 mm, 14 × 14 strip, planar germanium double sided strip detector (HpGeDSSD) has been used as a Compton Polarimeter to measure the linear polarization of photons emitted from aligned nuclei. Gamma rays following an alpha decay in the 227,228Th decay chains were used both for calibration of the device and for investigating the veracity of parity assignments based on systematic trends. An experimental arrangement of two interchangeable alpha detectors arranged 90 degrees apart allowed many systematic properties of the device to be investigated. Each of the pixels could be used both to scatter and absorb gamma rays, allowing high sensitivity (>60% of the Klein-Nishina formula) and high efficiency to be achieved. This combination yields a “figure of merit” of unprecedented value. A description of the experiment and current status of data analysis will be presented and the potential future uses of this device will be discussed. © 2005 American Institute of Physics [ABSTRACT FROM AUTHOR]

A proposed upgrade to the radioactive beam capability of the ATLAS facility has been proposed using 252Cf fission fragments thermalized and collected into a low-energy particle beam using a helium gas catcher. In order to reaccelerate these beams the ATLAS ECR-I will be reconfigured as a charge breeder source. A 1Ci 252Cf source is expected to provide sufficient yield to deliver beams of up to ∼103 far from stability ions per second on target. A brief facility description and the expected performance information are provided in this report. © 2005 American Institute of Physics [ABSTRACT FROM AUTHOR]

The heavy ion radiative capture reaction 12C(12C,γ) has been investigated around a beam energy of 16 MeV. The total cross-section has been measured with the Fragment Mass Analyser at Argonne National Laboratory and found to be somewhat larger than has previously been measured. A subsequent measurement with the Gammasphere array has shown that a considerable proportion of this extra cross-section relates to a highly non-statistical decay through high-lying states in 24Mg. © 2004 American Institute of Physics [ABSTRACT FROM AUTHOR]

The radiative capture reaction involving heavy ions is a relatively unexplored reaction mechanism which affords the possibility of gaining insights into molecular structure in nuclei and exotic, highly-deformed nuclear shapes. The [sup 12] C([sup 12]C,γ) reaction has been studied using an unconventional application of gamma-ray spectroscopy using the Gammasphere array. A resonance for this reaction has been located for E[sub beam]=15.8 MeV. Favored population of the K=2 rotational band in [sup 24]Mg as well as particular states around 10 MeV in excitation is observed. Using a Monte Carlo simulation of the previously uncharacterised high energy efficiency of Gammasphere, we set a lower limit on the cross-section for the species of decays observed of lµb. [ABSTRACT FROM AUTHOR]

Driven by a relentless decrease in feature size, the allowable particle contaminant size during semiconductor fabrication is now less than 100 nm. Particles in this size range (microcontaminants) in chemical vapor deposition (CVD) reactors are primarily gas-phase generated and are poorly understood. The purpose of the investigation described here is to enhance the understanding of the formation, transport and growth of microcontaminants in thermal CVD reactors. The approach being employed is to carry out a combined numerical/experimental study in which the particle dynamics are both modeled and optically probed in a rotating disk CVD reactor. The rotating disk configuration is utilized because of its simple and well-defined flow in which a particle layer forms in a highly accessible region of the reactor just above the substrate. Numerical/experimental comparisons of layer location and shape as a function of disk rotation rate are shown to be excellent if two empirically-determined parameters in the model are properly chosen. [ABSTRACT FROM AUTHOR]