Spin-23/2- Isomer of Lu177

Investigations of the decay of the three-particle state in Lu177 with spin 23/2- performed with the crystal diffraction technique revealed evidence for three-particle states in Hf177 and rotational bands in Lu177 and in Hf177. Levels with spins to 17/2 were found in the K=7/2+ rotational band in Lu177 while the K=7/2- and K=9/2+ bands in Hf177 were found to be excited up to spin 21/2 levels. From energy and intensity measurements of the cascade, crossover, and interband transitions, the values of a number of parameters pertinent to the collective model were derived. In particular, it was verified for each of the rotational bands that the quantity (gK-gR)/Q0 was a constant within the experimental error

Radiations from RaD and RaE

The electron and gamma-spectra from RaD and RaE have been thoroughly investigated. The gamma-radiation from RaD was studied with both krypton and argon proportional counters with brass and aluminum cathodes. The L alpha, L beta, and L gamma radiations of Bi were observed and identified with a critical absorber. The intensity ratios of L alpha:L beta:L gamma are 1:1:0.2. The previously reported 7.8-kev (10 percent) line was not found but could be strongly excited by copper backing. The weak 23-kev line (10^-3 per disintegration in our measurements) could be contributed from the piling effect of the detecting system. The conversion electrons of RaD were investigated in a solenoid magnetic spectrometer to obtain the L and (M+N) conversion coefficients. The results are: NeL / N beta =64 percent, NeM+N / N beta =21 percent, NeL+M+N / N beta =(85±5) percent. The conversion electrons of RaD were again investigated with a 180° beta-spectrometer with a resolution of 0.8 percent and a counter window of ~6 µg/cm2. The LI, LII, and LIII conversion lines of the 46.5-kev gamma-ray were resolved. The ratio of LI:LII:LIII:MI-III:MIV-V:NI-V:NVI-VIII+0 are 1:0.075:0.007: 0.25:0.006:0.07:0.007. From the ratios of the L-subshell conversion electrons, the 46.5-kev transition is interpreted as an M1 type. The upper limit of the intensity of the reported lines at 42 kev, at 37 kev, and at 31 kev must be less than 0.5 percent per disintegration if the same conversion coefficient is assumed. The unconverted 46.5-kev gamma-radiation is 0.07±0.02 per disintegration. Thus the excited state of 46.5 kev in RaE can account for (92±5) percent of the disintegrations. Neither internal conversion electrons nor nuclear gamma-radiations are found in RaE. A faint x-ray (~80 kev) of the order of 10-4 per disintegration due to the ionization effect was observed in RaE. A brief discussion of the decay scheme of RaD and the possible spin assignments of various levels is included

General Monte Carlo reliability simulation code including common mode failures and HARP fault/error-handling

A Monte Carlo Fortran computer program was developed that uses two variance reduction techniques for computing system reliability applicable to solving very large highly reliable fault-tolerant systems. The program is consistent with the hybrid automated reliability predictor (HARP) code which employs behavioral decomposition and complex fault-error handling models. This new capability is called MC-HARP which efficiently solves reliability models with non-constant failures rates (Weibull). Common mode failure modeling is also a specialty

Determination of Strong-Interaction Widths and Shifts of Pionic X-Rays with a Crystal Spectrometer

Pionic 3d-2p atomic transitions in F, Na, and Mg have been studied using a bent crystal spectrometer. The pionic atoms were formed in the production target placed in the external proton beam of the Space Radiation Effects Laboratory synchrocyclotron. The observed energies and widths of the transitions are E=41679(3) eV and Γ=21(8) eV, E=62434(18) eV and Γ=22(80) eV, E=74389(9) eV and Γ=67(35) eV, in F, Na, and Mg, respectively. The results are compared with calculations based on a pion-nucleus optical potential

Experimental evidence for parity impurity in a nuclear gamma transition

In this communication we present a preliminary account of an experimental investigation of parity admixture in nuclear states. Our measurements give evidence of a small parity admixture in a nuclear gamma transition of 482 keV in Ta181

Rotational and intrinsic levels in Tm169 and Lu175

Nuclear levels in Tm169 excited by electron capture of Yb169, and levels in Lu175 excited by both beta decay of Yb175 and electron capture of Hf175 have been studied by using the curved-crystal gamma-ray spectrometer and the ring-focusing beta-ray spectrometer, as well as a semicircular beta-ray spectrometer for low energies. From the precision energies and the multipolarity determinations, the levels in Tm169 have the following energies in kev, and spin and parity assignments: A (ground state) (½+), B 8.42 (3/2+), C 118.20 (5/2+), D 138.95 (7/2+), E 316.19 (7/2+), F 379.31 (7/2-), G 472.91 (9/2-). Levels A, B, C, and D are members of a rotational band whose characteristic constants are given. Levels E and F are interpreted as particle excitations and level G as a rotational level based on the state F. The Lu175 excited states have the following energies in kev, spins, and parities: A (ground state) (7/2+), B 113.81 (9/2+), C 251.46 (11/2+), D 343.40 (5/2+), E 396.31 (9/2-), F 432.76 (7/2+), G 504.7 (1/2+). A, B, and C form a rotational band for which the characteristic constants are given. Some features of the levels and transition probabilities are discussed and compared with the unified model. A brief survey of second-order rotational energy constants and of intrinsic excitation levels is given

Neutron production by cosmic-ray muons at shallow depth

The yield of neutrons produced by cosmic ray muons at a shallow depth of 32 meters of water equivalent has been measured. The Palo Verde neutrino detector, containing 11.3 tons of Gd loaded liquid scintillator and 3.5 tons of acrylic served as a target. The rate of one and two neutron captures was determined. Modeling the neutron capture efficiency allowed us to deduce the total yield of neutrons $Y_{tot} = (3.60 \pm 0.09 \pm 0.31) \times 10^{-5}$ neutrons per muon and g/cm$^2$. This yield is consistent with previous measurements at similar depths.Comment: 12 pages, 3 figure

Rotational spectrum of Tm171

The gamma rays emitted from Tm171 following the Er171 beta decay have been measured with the twometer curved-crystal spectrometer and a semicircular beta-ray spectrometer, enabling a comparison of the nuclear levels and rotational parameters for the Tm171 ground-state band with the corresponding levels and parameters of Tm169. The measured gamma rays have the following energies in kev: 5.06±0.05, 12.40±0.05, 111.63±0.02, 116.69±0.03, 124.03±0.03, 210.62±0.15, 284.9±0.7, 295.97±0.15, 308.37±0.15. In comparing the rotational parameters, a slight increase in the deformation of Tm171 over that of Tm169 is noted. The relatively large change in the decoupling parameter (a=-0.8563) for Tm171 compared with that of Tm169 cannot be accounted for entirely by the small change in nuclear deformation

Nuclear resonance excitation using a diffraction monochromator

Nuclear resonance scattering from the first excited states in F19 and Mn55 has been studied with the bent-diffraction-crystal monochromator. The experiment was performed by observing the scattered radiation from nuclei exposed to nearly monoenergetic x rays selected by crystal diffraction from the bremsstrahlung spectrum of an x-ray tube. Gamma rays scattered at 135° from samples of lithium fluoride and manganese placed in the diffracted beam were observed as a function of the incident photon wavelength. With the lithium fluoride sample three measurements were made under different experimental conditions. In each case pronounced resonance peaks 10 to 15% above background were observed. A least-squares analysis of the data gives 109.894±0.005 keV for the energy position of the first excited level in F19. From the observed yield the width of this level was deduced to be (5.1±0.7)×10^-7 eV. Measurements with a Mn55 scattering sample gave 125.95±0.01 keV for the position of the first excited level and (1.1±0.3)×10^-6 eV for the resonance width