The differential cross section for the elastic scattering of a particles by 40 Ca has been measured at sixteen angles between 5.0 and 12.5 MeV in 10-keV intervals. Complicated structure is seen in the excitation functions which is often as fine as the experimental resolution (<10 keV). There are many closely spaced anomalies which are substantially wider than the experimental resolution. Very broad undulations are apparent in averaged differential cross-section curves for which the averaging interval is about 0.5 MeV. The averaged data are analyzed in this work. Shape elastic scattering represented by an optical model where reaction channels are either closjed or strongly inhibited does not satisfactorily describe the angular distributions at the back angles. A combination of shape and compound elastic scattering reproduces the data except at the highest energies, where reaction cross sections are becoming significant. The expression for the compound elastic contribution to the cross section is based on Hauser-Feshbach theory and statisticalmodel considerations. Values obtained for the real potential-well depth of the optical model (^-440 MeV) are consistent with results previously obtained at higher energies for the same number of nodes in the s-wave function.
Vectorless test techniques are attractive methods to quichly and inexpensively identifj) and (1iugno.w common p r o m s related defects on maniifacturers' printed wiring hoards Junction Xyress I S U new AC wiethod developed to locate open und marginal rolder connections without the use of digital vectors or overclump style cupaci five probes Measuring response hurmowics rather thun simply the fiinrlulrientul AC respome reduces the tendency of f a h e accepts of open connecfions Description: Analog harmonic test (AHT) is a vectorless technique for identifyliig and diagnosing solder related defects including open connections and marginal coiinections which exhibit resistance values greater than 10 to 20 ohms. AHT can also readily {detect open bond wire connections inside integrated circuit packages and can determine whether the IC device is mis-oriented or completely missing.AHT operates by applying a DC biased AC signal to one dcvice pin on a semiconductor device and detecting thc effects of the applied signal on another pili of the same device. The applied A@ test signal typically passes through the device under test (DUT) electro-static protection diodes (ESD) or parasitic P-N structures and returns through the die substrate resistance.The detector pin which is brought into conduction by a DC bias supplies an AC signal path from the modulated substrate resistance to an external (digitizing meter. The response spectrum is then ;processed by both continuous time and discrete time tillers for increased frequency selectivity and rejection of noise. Open or marginal solder connections are ,identified by comparing the harmonic output :spectrum from each device lead against predetermined values.
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