Recent Articles

Persistence of the ${}^{12}C$ + ${}^{16}O$ → ${}^{28}{Si}$ Resonance in the Reaction ${}^{13}C$ ( ${}^{16}O$ , ${}^{17}O$ ) ${}^{12}C$

P. T. Debevec, H. J. Körner, and J. P. Schiffer

Phys. Rev. Lett. 31, 171 (1973) - Published 16 July, 1973

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An anomaly has been seen in the reaction ${}^{16}O$ + ${}^{13}C$ → ${}^{17}O$ + ${}^{12}C$ at a center-of-mass energy of 18.7 MeV. The energy, width, and angular distribution suggest that it is related to a $J^{π} = 14^{+}$ resonance that has been reported in the ${}^{16}O$ + ${}^{12}C$ system. The width and cross section imply a value near the single-particle limit. Possible models for such a resonance are mentioned.

Absence of Gravity-Wave Signals in a Bar at 1695 Hz

James L. Levine and Richard L. Garwin

Phys. Rev. Lett. 31, 173 (1973) - Published 16 July, 1973

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A 118-kg bar shows vector amplitude changes ("impulses") in successive 24-msec intervals which correspond to bar energies $E$ distributed with a probability $N = N_{0} \exp (- \frac{E}{k T_{e}})$ , with $T_{e} \sim 30$ K. Not more than one impulse larger than 537 K was observed in 9 days. Calibration impulses giving the bar 600 K of energy were detected with 60% efficiency above a 537-K threshold. In the following Letter, these results are contrasted with the gravity-wave detections of Weber.

Single Gravity-Wave Detector Results Contrasted with Previous Coincidence Detections

Richard L. Garwin and James L. Levine

Phys. Rev. Lett. 31, 176 (1973) - Published 16 July, 1973

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Coincidence detectors of Weber have given a 10:1 ratio ( $R^{*}$ ) of prompt to delayed coincidences. Simplified analysis indicates that such an $R^{*}$ would require daily gravity-wave incidence rate and energy depositions that would have been seen in the single-bar detector of the preceding Letter (and were not), suggesting that Weber's 1969-1970 events were not produced by gravity waves or that such waves do not exist in similar numbers and intensity in 1973.

Lower Bound on the Intermediate-Boson Mass

B. C. Barish, J. F. Bartlett, D. Buchholz, T. Humphrey, F. S. Merritt, Y. Nagashima, F. J. Sciulli, D. Shields, H. Suter, G. Krafczyk, and A. Maschke

Phys. Rev. Lett. 31, 180 (1973) - Published 16 July, 1973

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We report a search for the $W$ boson via the production process $ν_{μ} + Z \to W^{+} + μ^{-} + Z$ and decay process $W^{+} \to μ^{+} + ν_{μ}$ . We have set a firm lower bound on the mass of the $W$ boson as a function of the branching fraction into leptons [ $B = \frac{(W \to l + ν)}{(W \to all)}$ ]. For example, we have determined that $M_{W} > 4.4$ GeV/ $c^{2}$ (90% confidence limit) for $B = 0.5$ .

Meson-Exchange Corrections to the Cross Section for $n + H^{2} \to H^{3} + γ$

E. Hadjimichael

Phys. Rev. Lett. 31, 183 (1973) - Published 16 July, 1973

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Surface-State Transitions of Silicon in Electron Energy-Loss Spectra

J. E. Rowe and H. Ibach

Phys. Rev. Lett. 31, 102 (1973) - Published 9 July, 1973

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Surface-state transitions on ordered silicon (100)2×1 and (111)7×7 surfaces have been observed by electron energy-loss spectroscopy. The surface transitions were identified by comparing the clean ordered surfaces with clean disordered surfaces, and with disordered surfaces due to submonolayer quantities of absorbed oxygen. Three transitions are observed corresponding to surface states near the top, near the middle, and at the bottom of the valence band. These surface-state transitions are stronger on the (111)7×7 surface than on the (100)2×1 surface.

Surface States and Surface Bonds of Si(111)

Joel A. Appelbaum and D. R. Hamann

Phys. Rev. Lett. 31, 106 (1973) - Published 9 July, 1973

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A realistic smooth potential is constructed for the Si(111) surface both with and without relaxation of the surface atoms. In both cases, a single band of surface states whose charge is highly localized in "dangling bonds" is found in the energy gap. In the relaxed case, two new bands of surface states appear, lying 2.0-3.6 eV and 10.7-12.9 eV below the valence-band maximum, and localized in the back bonds of the surface atoms.

Feasibility of Nuclear Polarization of ${}^{3}{He}^{+ +}$ Ions by Electron-Transfer Processes

O. Karban, S. W. Oh, and W. B. Powell

Phys. Rev. Lett. 31, 109 (1973) - Published 9 July, 1973

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Observation of the Sign of the Nuclear Quadrupole Interaction by $β - γ$ Directional Correlations

R. S. Raghavan, P. Raghavan, and E. N. Kaufmann

Phys. Rev. Lett. 31, 111 (1973) - Published 9 July, 1973

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We have demonstrated for the first time the possibility of determining the sign of the nuclear quadrupole interaction by $β - γ$ directional correlations in a noncubic single crystal. A simple time-differential measurement on the 828-keV level of ${}^{115}{In}$ populated by the allowed (Gamow-Teller) $β$ decay of ${}^{115}{Cd}$ yields the value of the quadrupole interaction of this level in a single crystal of Cd metal to be $\frac{e^{2} qQ}{h} = + 146 (5)$ MHz.

Low-Lying One-Proton, Three-Neutron-Hole States in ${}^{206}{Bi}$

M. Fujioka, M. Kanbe, and K. Hisatake

Phys. Rev. Lett. 31, 114 (1973) - Published 9 July, 1973

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Precision conversion-electron and $γ$ -ray measurements have revealed a strong $M 1$ transition of 10.84 keV between the first and the second excited states of ${}^{206}{Bi}$ , resulting in a substantial revision of the previous decay scheme of ${}^{206}{Po}$ . Thus it has become possible to interpret some of the low-lying states in ${}^{206}{Bi}$ in terms of one-proton, three-neutron-hole configurations, in correspondence with the one-proton, one-neutron-hole multiplets in ${}^{208}{Bi}$ .

Finite-Range Calculations of the $j$ Dependence of ( ${}^{12}C$ , ${}^{11}B$ ) and ( ${}^{16}O$ , ${}^{15}N$ ) on ${}^{62}{Ni}$

L. A. Charlton

Phys. Rev. Lett. 31, 116 (1973) - Published 9 July, 1973

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Full finite-range calculations, including recoil effects exactly, have been performed for single-proton-transfer reactions on ${}^{62}{Ni}$ . Projectiles of ${}^{16}O$ and ${}^{12}C$ are considered. It is found that the ratios of cross sections leading to the ground and first excited states in ${}^{63}{Cu}$ are in good agreement with experiment. This is not true when recoil is neglected.

On-Line Mass-Spectrometric Measurement of the Masses of Neutron-Rich Sodium Isotopes

R. Klapisch, R. Prieels, C. Thibault, A. M. Poskanzer, C. Rigaud, and E. Roeckl

Phys. Rev. Lett. 31, 118 (1973) - Published 9 July, 1973

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Nuclear Response Function

G. F. Bertsch

Phys. Rev. Lett. 31, 121 (1973) - Published 9 July, 1973

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A fast numerical method is described for calculating nuclear excitation properties with $δ$ -type interactions. The method is applied to ${}^{208}{Pb}$ , and the following properties of the nucleus are found: (i) The quadrupole strength has two main pieces, one a low state and one identifiable as the giant quadrupole; (ii) excitations with $L > 2$ do not seem to have high-energy collective parts; (iii) the giant dipole $L = 1$ , $T = 1$ is too low unless the interaction has a strong momentum dependence.

Nonlinear-Evolution Equations of Physical Significance

Mark J. Ablowitz, David J. Kaup, Alan C. Newell, and Harvey Segur

Phys. Rev. Lett. 31, 125 (1973) - Published 9 July, 1973

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We present the inverse scattering method which provides a means of solution of the initial-value problem for a broad class of nonlinear evolution equations. Special cases include the sine-Gordon equation, the sinh-Gordon equation, the Benney-Newell equation, the Korteweg-de Vries equation, the modified Korteweg-de Vries equation, and generalizations.

Energy Spectrum of Nuclei with $Z >~ 60$ as Evidence for a New Source of Cosmic Rays

W. Z. Osborne, L. S. Pinsky, E. K. Shirk, P. B. Price, E. J. Kobetich, and R. D. Eandi

Phys. Rev. Lett. 31, 127 (1973) - Published 9 July, 1973

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We have found the energy spectrum of cosmic rays with $Z >~ 60$ to be much steeper in the neighborhood of 1 GeV/amu than measured spectra of less massive cosmic rays. The data analysis includes effects due to solar modulation. This low-energy enhancement of high- $Z$ primaries implies sources which either are strongly enriched in very heavy elements or have a $Z$ -dependent acceleration mechanism.

Vector-Meson Electroproduction at High $Q^{2}$

L. Ahrens, K. Berkelman, G. S. Brown, D. G. Cassel, W. R. Francis, P. H. Garbincius, D. Harding, D. L. Hartill, J. L. Hartmann, R. L. Loveless, R. C. Rohlfs, D. H. White, and A. J. Sadoff

Phys. Rev. Lett. 31, 131 (1973) - Published 9 July, 1973

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We have measured $ρ^{0}$ , $ω$ (combined) and $ϕ$ electroproduction over a range of virtual-photon four-momentum $Q^{2}$ from 0.4 to 2.2 ${GeV}^{2}$ and for photon energies $ν$ from 2.7 to 8.6 GeV. We find that the slope of the $t$ (momentum transfer) dependence of the $ρ^{0}$ and $ω$ forward peak decreases with increasing $Q^{2}$ to less than half of the photoproduction slope.

Transverse-Momentum Distribution of Pions in High-Energy $pp$ Collisions

Minh Duong-van and P. Carruthers

Phys. Rev. Lett. 31, 133 (1973) - Published 9 July, 1973

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Light-Cone Dominance in Inclusive $e^{-} e^{+}$ Annihilation

John Ellis and Yitzhak Frishman

Phys. Rev. Lett. 31, 135 (1973) - Published 9 July, 1973

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Transverse-Momentum Limitation in the One-Dimensional Gas Model

Leo Stodolsky

Phys. Rev. Lett. 31, 139 (1973) - Published 9 July, 1973

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A strict application of the assumptions of the pion rapidity-gas model of multiproduction, together with simple kinematics, imply a connection between the coupling strength $C$ and the average transverse mass ${\bar{μ}}_{T}$ , which is $C ≲ \frac{M}{{\bar{μ}}_{T}}$ , with $M$ a typical leading particle mass. The most important consequence is that if $C$ is large, as it is experimentally, ${\bar{μ}}_{T}$ must be small, and thus a strong transverse-momentum limitation need not be introduced as a separate assumption. Furthermore $C$ is limited to order 1 (which incidentally means that there must be a critical coupling constant in the multiperipheral model). Experimentally $C$ appears to be near its maximal value. We indicate that there is a kind of model in which this arises automatically.

Fluorescence Yield of Carbon

A. Langenberg and J. van Eck

Phys. Rev. Lett. 31, 71 (1973) - Published 9 July, 1973

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Absolute cross sections for carbon $K$ -shell x-ray production are measured and compared for the case of 0.1-1-MeV protons incident on thin solid targets (carbon foils) and a gaseous target (methane). These x-ray results combined with Auger measurements provide a fluorescence yield $ω_{K}$ which is independent of the proton energy.

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Persistence of the ${}^{12}C$ + ${}^{16}O$ → ${}^{28}{Si}$ Resonance in the Reaction ${}^{13}C$ ( ${}^{16}O$ , ${}^{17}O$ ) ${}^{12}C$

Absence of Gravity-Wave Signals in a Bar at 1695 Hz

Single Gravity-Wave Detector Results Contrasted with Previous Coincidence Detections

Lower Bound on the Intermediate-Boson Mass

Meson-Exchange Corrections to the Cross Section for $n + H^{2} \to H^{3} + γ$

Surface-State Transitions of Silicon in Electron Energy-Loss Spectra

Surface States and Surface Bonds of Si(111)

Feasibility of Nuclear Polarization of ${}^{3}{He}^{+ +}$ Ions by Electron-Transfer Processes

Observation of the Sign of the Nuclear Quadrupole Interaction by $β - γ$ Directional Correlations

Low-Lying One-Proton, Three-Neutron-Hole States in ${}^{206}{Bi}$

Finite-Range Calculations of the $j$ Dependence of ( ${}^{12}C$ , ${}^{11}B$ ) and ( ${}^{16}O$ , ${}^{15}N$ ) on ${}^{62}{Ni}$

On-Line Mass-Spectrometric Measurement of the Masses of Neutron-Rich Sodium Isotopes

Nuclear Response Function

Nonlinear-Evolution Equations of Physical Significance

Energy Spectrum of Nuclei with $Z >~ 60$ as Evidence for a New Source of Cosmic Rays

Vector-Meson Electroproduction at High $Q^{2}$

Transverse-Momentum Distribution of Pions in High-Energy $pp$ Collisions

Light-Cone Dominance in Inclusive $e^{-} e^{+}$ Annihilation

Transverse-Momentum Limitation in the One-Dimensional Gas Model

Fluorescence Yield of Carbon

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