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We present 264 new interseismic GPS velocities from the Mobile Array of GPS for Nevada Transtension (MAGNET) and continuous GPS networks that measure Pacific–North American plate boundary deformation in the Central Walker Lane. Relative to a North America-fixed reference frame, northwestward velocities increase smoothly from ∼4 mm/yr in the Basin and Range province to 12.2 mm/yr in the central Sierra Nevada resulting in a Central Walker Lane deformation budget of ∼8 mm/yr. We use an elastic block model to estimate fault slip and block rotation rates and patterns of deformation from the GPS velocities. Right-lateral shear is distributed throughout the Central Walker Lane with strike-slip rates generally

The objectives of this study were to assess the correlation between hoof surface temperature and ultrasonographic measurements of digital blood vessels in horses and to evaluate the measurements' potential as predictors for clinical lameness. Twelve 3-year-old American Quarter Horses, 6 geldings and 6 mares, with average initial body weight of 459 ± 31 kg were used. On days 0, 30, 60, and 90 of the study, horses were weighed and subjected to clinical lameness examinations. Doppler ultrasonography was used to measure diameter of the medial palmar artery in the distal left forelimb and velocity of blood flow through that artery, starting at 60 minutes after morning feeding and repeated at 30-minute intervals. Temperature measurements on the hoof were collected at 15-minute intervals beginning 75 minutes after feeding, using a digital thermographic camera. A series of bivariate linear mixed models were fitted to estimate the correlation between Doppler and temperature measurements. The within-horse and between-horse correlations between hoof surface temperature and velocity of blood flow in the distal limb through the medial palmar artery was estimated at 0.40 (P > .50) and 0.99 (P

The purpose of this study was to examine the effect of interstimulus interval (ISI) on ethanol-induced place aversion in rats. Six groups of rats initially received four pairings of a distinctive floor stimulus (CS+) with ethanol (1 g/kg, I.P.) and four pairings of a different floor stimulus (CS-) with saline. Groups -30, -15, -10, -5, 0, and 5 were injected 30, 15, 10, 5, or 0 min before, or 5 min after exposure to the 5 min CS, respectively. After testing for place aversion, all groups were exposed to an additional set of conditioning trials using a higher dose of ethanol (1.5 g/kg). During the first test, only groups 0 and -15 exhibited conditioned place aversion. However, during the second test, all groups showed conditioned aversion except group -30. The results suggest that ethanol's aversive effects dissipate by 30 min postinjection or that it is more difficult to associate those effects with short-duration external stimuli at long backward intervals. In contrast to recent findings with mice, the direction of ethanol-induced place conditioning was not altered in rats exposed to different ISIs.

Specially developed large area silicon detectors were used for electromagnetic shower calorimeters. Tests have been performed in the energy range between 1 and 6 GeV. Measurements of shower development, visible energy and energy resolution are presented and compared to those obtained in other experiments.

A brief outline of the advantages in using silicon detectors for applications in high energy physics is given. In preparation for investigations at HERA a compact silicon-lead calorimeter for the detection of electromagnetic showers was constructed, calibrated and tested. The experimental results are in good agreement with Monte Carlo calculations. An overall energy resolution of 20.7% √E was obtained.

A constant fraction type electronic circuit is described that performs a pulse shape analysis of organic scintillator pulses. The main features are: stability at high counting rates and energy independent particle identification over a wide energy range. In conjunction with a NE 213 scintillator, n - γ discrimination over a dynamic range of more than 1:100 can be performed at counting rates up to 5 × 10 4 pulses per second.

Angular distributions of the 3 H(d, n) 4 He neutron source reaction have been measured with a recoil proton detector for deuteron energies from 8 MeV to 16 MeV in 1 MeV steps. The relative distributions are related by means of an excitation function taken at zero degrees. The results are compared with recent data obtained with time-of-flight techniques. Calculations with phase shifts from the refined cluster model were performed, which included partial waves up to l = 3 and the two particle channels 3 H + d, n + 4 He and n + 4 He ∗ . They show remarkable agreement with the experimental angular distributions both in shape and in absolute magnitude.

Total neutron cross-sections in the energy range from 4.2 to 6.2 MeV are measured for sodium, potassium and calcium using the transmission method. Mono-energetic neutrons are produced via the reaction D(d, n)He 3 in a deuterium gas target with the deuteron beam of a 3 MeV Van de Graaff generator. A neutron energy resolution of about 30 KeV is achieved. The transmission is measured with a stilbene scintillation spectrometer in steps of about 50 keV. The cross-sections clearly exhibit pronounced structures with widths of 100–150 keV which are very probably due to statistical fluctuations of the compound nucleus level density.

The activation method was used to measure excitation functions for total or isomeric (n, 2n) cross sections in the energy region 12–18 MeV for 93 Nb, 96 Ru, 104 Ru, 103 Rh, 102 Pd, 110 Pd, 128 Te, 130 Te, 142 Nd, 192 Os, 191 Ir and 198 Pt. Isomeric (n, 2n) cross-section ratios were measured for 110 Pd, 128 Te, 130 Te and 198 Pt in the whole energy region stated and were further obtained for 93 Nb and 103 Rh for two energies by combining experimental isomeric cross sections with special (n, 2n) cross-section systematics. The measured total (n, 2n) cross sections are discussed with respect to the dependence of this quantity on the neutron excess of the target nucleus. Later the results are compared with predictions from the statistical theory and special consideration is given to the competition between γ and neutron emission. From the isomeric cross-section ratios spin cut-off parameters σ(& h ;) were deduced according to the method of Vandenbosch and Huizenga. The same analysis was also applied to all isomeric (n, 2n) crosssection ratios available from the literature. The resulting properties of σ(&ħ;) are compared with the theoretical predictions.

Excitation functions of neutron induced reactions were measured in the energy range 12.6–19.6 MeV by means of the activation method. Results for the following reactions are reported: (n, 2n) reaction in N14, F19, K39, Ga69 and Sr88, (n, p) reaction in F19 and Zn66 and (n, α) reaction in Mn55. The results are compared with corresponding measurements published by other authors. In the case of the heavier target elements a comparison is also made with the predictions of the statistical theory using compound nucleus cross sections evaluated in the optical model and applying the level density formula given by Lang. Gamma emission as a competing process in the decay of the compound nucleus is also taken into account. The agreement of the theoretical predictions with the experimental results is poor. This, probably, is caused mainly by the level density parameters.

The excitation functions of the (n, p) reactions for 41K and 64Zn and of the (n, 2n) reactions for 55Mn, 63Cu, 65Cu, 64Zn and 66Zn were measured in the energy region 13–18 MeV by the activation method. The experimental results are compared with statistical-theory predictions based on optical-model absorption cross sections and the Fermi gas model nuclear level density formula. Three different proposals to account for the pairing effect in the nuclear level density are compared. The dependence of (n, 2n) cross sections on the neutron excess of the target nucleus is discussed.

The systematics of the available total (n, 2n) reaction cross-sections for 14 MeV neutrons have been investigated for even-neutron target nuclei. The existence of neutron shell effects is found and discussed on the background of the statistical theory. Minima in the (n, 2n) cross-sections at the magic neutron numbers N=28 and 50 for even and N=20 for odd-proton target nuclei can be accounted for by similar trends in the Q values. Cross-section maxima at the closed neutron shells N=82 and 126 for even and N = 28, 50, 82 and 126 for odd-proton target nuclei can be understood as an effect of shell closure on the nuclear level density, the relative decrease of which on passing across a closed shell is larger for higher excitation energies. The (n, n′γ) reaction is the principal one competing with the (n, 2n) process at 14 MeV in the medium and heavy mass regions. Since for the (n, n′γ) reaction the residual excitation energies lies in the region up to 12 MeV, whereas for the (n, 2n) reaction, it does not exceed 4 MeV, and since the relative change in the level density is greater at the higher excitation energies, the competition between (n, n′γ) and (n, 2n) reactions favours the latter in the region of closed neutron shells and thus accounts for the observed maxima in the (n, 2n) cross-section systematics.

Special computer-programs are discussed which may be used in the analysis of measurements of fast neutron cross sections applying the activation method. For various shapes of the activated samples the average neutron energy and the average neutron flux density are calculated for the monoenergetic fast neutron sources usually used in experiments. Moreover, a method is described for deducing the absolute activities from the measured total decay curve which works sufficiently well also if several activities with different half-lives and intensities are present. All programs are written in ALGOL and are available on request.

The angular distributions and energy spectra of α-particles from neutron induced reactions have been measured at En = 14.2 MeV for the target nuclei 63Cu, 93Nb, 103Rh, 107Ag, 127I and 133Cs. The measured quantities can consistently be divided into contributions from direct and compound nuclear mechanisms. The ratio of these contributions as a function of the target mass number A is discussed. The compound parts of the reactions can be interpreted in terms of the statistical model using the Fermi gas model approximation for the level density and optical-model absorption cross sections. The deduced values for the level density parameter a and the spin cut-off parameter σ are compared with existing systematics and theoretical predictions.

If the method of recoil detection in organic scintillators shall be used for measuring the flux of fast neutrons with good accuracy corrections have to be applied for accounting for various effects distorting the recoil spectrum. This problem is investigated experimentally as well as theoretically for a 1“ dia. ×1“ stilbene scintillator for neutrons in the energy region 2.6−14.1 MeV. A Monte Carlo method is used for calculating the distortion of the recoil proton spectrum by multiple neutron scattering, edge-effects and nonlinear response of the scintillator. Theoretical and experimental corrections to be applied to the integral recoil proton spectrum used for the flux measurement are given. An accuracy of better than 4% for the flux determination is claimed.

A chamber with one CsI(Tl)-scintillation counter has been used for the investigation of fast neutron reactions in which charged particles are emitted. Different types of radiation are distinguished by applying the pulse-shape discrimination method. Angular distributions can by measured by successively setting up the targets at different places around the crystal the position of which is fixed relative to the neutron source. The results obtained for the energy and angular distributions of the alpha particles from 14.1 MeV neutron reactions in Al 27 and Ni 58 are presented. A statistical theory analysis leads to the conclusion that the alpha particles predominantly are evaporated in compound nucleus reactions. Reasonable values for the level density parameter a , the nuclear temperature T and the spin cut-off parameter σ are derived from the data. The alpha particles from Al 27 can be attributed entirely to the reaction Al 27 (n, α)Na 24 for which a cross section of 119±10 mb is measured. The total alpha particle yield from Ni 58 is the sum of the contributions from the reactions Ni 58 (n, α)Fe 55 , Ni 58 (n, αn′)Fe 54 and Ni 58 (n, n′α)Fe 54 . The portion of alpha particles from the latter reaction is separated by means of the statistical theory, and a cross section of 30±6 mb is determined for this process. For the sum of the other two reactions a cross section of 125±16 mb is obtained. Arguments are given for the statement that at least ninety per cent of this cross section may be attributed to the reaction Ni 58 (n, α)Fe 55 . As far as possible the results are compared with corresponding ones of other authors.

Fast neutron cross sections for (n, p), (n, t), (n, α), (n, 2n), (n, np), and (n, nα) reactions, leading to all possible final states, are presented in graphic form. Neutron energies range up to 20 MeV. Targets include nuclei from H 2 to U 238 . The compilation covers data available in June 1965.

An electronic circuit for the pulse shape analysis used for the discrimination of α -particles with energies down to 1.5 MeV against an intensive proton and gamma background is described.