Recent Articles

Decays of the lowest $T = 2$ state in ${}^{44}{Ti}$

S. J. Freedman, C. A. Gagliardi, M. A. Oothoudt, A. V. Nero, R. G. H. Robertson, F. J. Zutavern, E. G. Adelberger, and A. B. McDonald

Phys. Rev. C 17, 2071 (1978) - Published 1 June, 1978

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The ${}^{46}{Ti} (p, t) {}^{44}{Ti}$ reaction is used to populate the lowest $T = 2$ level and decay products from the level are detected in coincidence. The branching ratio for isospin forbidden $α$ decay to ${}^{40}{Ca}$ (g.s.) is $\frac{Γ_{α}}{Γ} = (32 \pm 5) %$ ; the directly measured $γ$ -decay branching ratio is $\frac{Γ_{γ}}{Γ} = (54 \pm 11) %$ . The proton decay branching ratio is found to be less than 4%.

NUCLEAR REACTIONS ${}^{46}{Ti} (p, t)$ , $E_{p} = 42$ MeV. Measured charged particle and $γ$ branching ratios from 9.338 MeV ( $0^{+}$ , 2) level. Measured charged particle branching ratios from 9.298 MeV level.

Inhibited electric-quadrupole transitions in odd-neutron spherical nuclei

R. E. Holland, F. J. Lynch, and B. D. Belt

Phys. Rev. C 17, 2076 (1978) - Published 1 June, 1978

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A number of inhibited electric-quadrupole transitions have been found in odd- $N$ nuclei, and their lifetimes have been measured. The pairing-plus-quadrupole model predicts a correlation between these lifetimes and the shell-model occupation numbers which can be obtained from pickup and stripping reactions. The correlation observed is about that expected from the accuracy of the data on occupation numbers.

NUCLEAR REACTIONS $d$ , $α$ , ${}^{3}{He}$ , $E_{α} = 12$ MeV, pulsed beam, measured $E 2$ transition rates in ${}^{63}{Ni}$ , ${}^{65}{Ni}$ , ${}^{99}{Mo}$ , ${}^{103}{Ru}$ , ${}^{105}{Ru}$ , ${}^{107}{Pd}$ , ${}^{108}{Pd}$ , ${}^{109}{Cd}$ , ${}^{111}{Sn}$ , ${}^{115}{Sn}$ compared to prediction pairing-plus-quadrupole model.

Relativistic two-fluid model of nucleus-nucleus collisions

Anthony A. Amsden, Alfred S. Goldhaber, Francis H. Harlow, and J. Rayford Nix

Phys. Rev. C 17, 2080 (1978) - Published 1 June, 1978

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To take into account the expected partial transparency of nuclei during collisions at high energy, we introduce a two-fluid dynamical model, in which coupled relativistic equations of motion are solved for separate target and projectile nuclear fluids. The terms in the equations that couple the two nuclear fluids are obtained from the cross section and momentum transfer for individual nucleon-nucleon collisions. At low relative velocities the target and projectile fluids merge, in which case the conventional one-fluid dynamical model is recovered. For a given nuclear equation of state and for given initial conditions, the equations of motion are solved as functions of time for the nucleon number density, momentum density, energy density, pressure, and velocity for each fluid. This is done in three spatial dimensions by means of a relativistic generalization of a standard particle-in-cell finite-difference computing method for multiphase fluid-dynamics problems. For each of several impact parameters, the velocity distribution at some large time is converted to an energy and angular distribution for the expanding matter. Integration of these results over impact parameter then gives the double differential cross section $\frac{d^{2} σ}{dEd Ω}$ . For ${}^{20}{Ne}$ + ${}^{238}U$ at laboratory bombarding energies per nucleon of 250 MeV, 400 MeV, and 2.1 GeV, as well as for ${}^{4}{He}$ + ${}^{238}U$ at a laboratory bombarding energy per nucleon of 400 MeV, we compare calculated and experimental energy spectra for outgoing charged particles at several laboratory angles. The calculations reproduce correctly the experimental slopes at each angle, as well as the overall decrease in the experimental cross section when going from forward to backward angles. However, for ${}^{20}{Ne}$ + ${}^{238}U$ at laboratory bombarding energies per nucleon of 250 and 400 MeV, the calculated values at 30° are only one-third the experimental values. Also, for ${}^{4}{He}$ + ${}^{238}U$ at a laboratory bombarding energy per nucleon of 400 MeV, the calculated values at all angles are substantially smaller than the experimental values. As a prediction for future experiments, we also use the theory in a context where our numerical approximations and simplifications (such as neglecting the diffuseness of the nuclear surface) should be more reliable, to deduce results for ${}^{238}U$ + ${}^{238}U$ at laboratory bombarding energies per nucleon of 250 MeV and 2.1 GeV. By means of a one-dimensional calculation we also study the maximum compression and excitation that can be achieved in such collisions. The maximum rest-frame compression is about 2.4 to 2.6 at a bombarding energy per nucleon of 250 MeV, and is about 6 to 8 at a bombarding energy per nucleon of 2.1 GeV. The available energy is primarily in the form of compressional energy, with little in the form of internal excitation energy, Significant rest-frame compressions (greater than twice normal density for 250 MeV and greater than 3 times normal density for 2.1 GeV) are achieved for substantial numbers of nucleons and substantial time periods.

NUCLEAR REACTIONS ${}^{20}{Ne}$ + ${}^{238}U$ , $\frac{E_{bom}}{20} = 250 MeV, 400 MeV, 2.1 GeV$ ; ${}^{4}{He}$ + ${}^{238}U$ , $\frac{E_{bom}}{4} = 400 MeV$ ; ${}^{238}U$ + ${}^{238}U$ , $\frac{E_{bom}}{238} = 250 MeV, 2.1 GeV$ . Calculated $\frac{d^{2} σ}{dEd Ω}$ for outgoing charged particles. Relativistic two-fluid dynamical model, nuclear equation of state, nuclear matter at high density and high excitation energy.

Observation of intermediate structure resonances in the ${}^{12}C$ ( ${}^{16}O$ , ${}^{16}O$ ( $0^{+}$ , 6.05)) reaction

R. E. Malmin, Fide Kahn, and P. Paul

Phys. Rev. C 17, 2097 (1978) - Published 1 June, 1978

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The population of the 6.05-MeV $0^{+}$ state in ${}^{16}O$ in the ${}^{12}C$ + ${}^{16}O$ reaction was measured for $E_{lab} ({}^{16}O) = 46 - 56$ MeV by detecting the $0^{+}$ → g.s. pair transition. ${}^{12}C$ recoil pair and $γ$ coincidence spectra were obtained at the $L = 14$ resonance at 46.3 MeV to obtain the relative population of the 6.13-MeV $3^{-}$ and 6.05-MeV $0^{+}$ states. The total pair cross section reveals resonances at $E_{lab} = 48, 51.4, 52.9, and 55.5$ MeV which are correlated with resonances seen in other channels. The ratio of resonant cross sections $\frac{σ (0^{+})}{σ (3^{-})}$ varies between 0.014 and 0.080. Reduced widths extracted for the $0^{+}$ excitation channel are of the same order as those of the $3^{-}$ and 6.92-MeV $2^{+}$ final state channels. This indicates that the weak $0^{+}$ cross section is caused by the energy-angular-momentum mismatch rather than by the structure of the resonance wavefunction.

NUCLEAR REACTIONS ${}^{12}C$ ( ${}^{16}O$ , ${}^{16}O$ ( $0^{+}$ , 6.05 MeV)) ${}^{12}C$ , $E = 46 - 56$ MeV, detect $e^{+} - e^{-}$ pairs; measure $σ (E)$ , deduce resonances, reduced widths.

Localization of various reaction processes for weakly bound heavy projectiles

L. Jarczyk, J. Oko¢lowicz, A. Strza¢lkowski, H. Wita¢la, W. Zipper, J. Lang, R. Müller, E. Ungricht, and J. Unternährer

Phys. Rev. C 17, 2106 (1978) - Published 1 June, 1978

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The interaction of ${}^{9}{Be}$ ions with ${}^{28}{Si}$ target nuclei was investigated by measuring elastic scattering cross sections and evaporation spectra. The behavior of the elastic scattering cross sections as a function of the classical distance of closest approach indicates a localization of direct reaction processes in the far tail region of the interaction potential, whereas fusion with compound nucleus formation sets in at considerably shorter distances. A statistical model analysis of the evaporation spectra led to a value of $σ_{fus} = 735$ mb for the fusion cross section, whereas the total reaction cross section as determined from the elastic scattering data amounts to $σ_{R} = 1120$ mb. This difference is a peculiar phenomenon of the very weakly bound ${}^{9}{Be}$ system.

NUCLEAR REACTIONS ${}^{28}{Si}$ ( ${}^{9}{Be}$ , ${}^{9}{Be}$ ), ( ${}^{9}{Be}, α$ ), ( ${}^{9}{Be}, p$ ), $E_{lab} = 20$ MeV, measured $σ (E, θ)$ , deduced $σ_{fus}$ , $σ_{R}$ .

Recoil distance lifetime measurements in ${}^{69}{As}$ and ${}^{72}{Se}$

H. P. Hellmeister, E. Schmidt, M. Uhrmacher, R. Rascher, K. P. Lieb, and D. Pantelica

Phys. Rev. C 17, 2113 (1978) - Published 1 June, 1978

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High spin state in ${}^{69}{As}$ and ${}^{72}{Se}$ have been excited in oxygen induced reactions on ${}^{56}{Mn}$ , ${}^{54, 56}{Fe}$ , and ${}^{58}{Ni}$ targets. On the basis of $γ γ$ coincidences, angular distributions, and excitation functions, a level scheme of ${}^{69}{As}$ is proposed. The following mean lives (in the parentheses) have been determined by the recoil distance Doppler shift method: in ${}^{72}{Se}$ with level energies in keV, 862 (5.2 ± 0.5 ps); 1634 (2.7 ± 0.3 ps); 2466 (2.2 ± 0.3 ps); 3770 (9 ± 3 ps); in ${}^{69}{As}$ , 1307 (1.95 ± 0.05 ns); 2161 (5.1 ± 0.8 ps); 5198 (11.3 ± 1.5 ps). It is suggested that the positive parity states in ${}^{69}{As}$ form a rotational aligned $g_{\frac{9}{2}}$ proton band with $γ ≃ 30 °$ . The presumed ${25 / 2}^{+}$ intruder state features the same deformation as deduced from the ${13 / 2}^{+}$ → ${9 / 2}^{+}$ $B (E 2)$ value.

NUCLEAR REACTIONS ${}^{54}{Fe} ({}^{18}O, p 2 n) {}^{69}{As}$ , ${}^{56}{Fe} ({}^{16}O, p 2 n) {}^{69}{As}$ , ${}^{55}{Mn} ({}^{16}O, 2 n) {}^{69}{As}$ , ${}^{58}{Ni} ({}^{16}O, α p) {}^{69}{As}$ , ${}^{58}{Ni} ({}^{16}O, 2 p) {}^{72}{Se}$ ; measured $E_{γ}$ , relative excitation function, angular distributions, recoil distance Doppler shift; deduced $E_{x}$ , $I^{π}$ , $T_{\frac{1}{2}}$ , mixing ratio.

Two theoretical potential models and the elastic scattering of ${}^{16}O$ from ${}^{63, 65}{Cu}$ at 40-46 MeV

H. Wojciechowski, N. B. J. Tannous, R. H. Davis, D. Stanley, M. Golin, and F. Petrovich

Phys. Rev. C 17, 2126 (1978) - Published 1 June, 1978

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Experimental differential cross sections for the elastic scattering of ${}^{16}O$ from ${}^{63}{Cu}$ at $E_{lab} = 40, 42, and 46$ MeV and ${}^{65}{Cu}$ at $E_{lab} = 41 and 46$ MeV are presented. The data are analyzed using a four parameter Woods-Saxon optical potential. Optical parameters are presented and it is verified that the experimental data are sensitive to the value of the real nuclear optical potential [ $Re U_{opt}^{N} (r)$ ] and its slope near the strong absorption radius ( $D_{\frac{1}{2}}$ ). Fits to the data are also obtained using the real nuclear potentials given by two theoretical models—the adiabatic model of Nix and collaborators and a $G$ -matrix double folding model. The potentials from the $G$ -matrix model give a better description of the data than the potentials from the adiabatic model. The latter have too small a slope. A possible explanation for this deficiency is suggested.

NUCLEAR REACTIONS ${}^{63, 65}{Cu}$ ( ${}^{16}O$ , ${}^{16}O$ ); measured $σ (θ, E)$ , $E = 40 - 46$ MeV; calculated $σ (θ)$ , $G$ matrix and adiabatic potential models.

Complete fusion of ${}^{16, 18}O$ with ${}^{24, 26}{Mg}$

S. L. Tabor, D. F. Geesaman, W. Henning, D. G. Kovar, K. E. Rehm, and F. W. Prosser, Jr.

Phys. Rev. C 17, 2136 (1978) - Published 1 June, 1978

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Total fusion cross sections for ${}^{16}O$ + ${}^{24}{Mg}$ , ${}^{16}O$ + ${}^{26}{Mg}$ , and ${}^{18}O$ + ${}^{24}{Mg}$ have been measured in the energy range $18 MeV \leq E_{c . m .} \leq 50 MeV$ by detection of the evaporation residues. In addition, elastic scattering angular distributions have been measured and analyzed with the optical model. The fusion cross section for ${}^{16}O$ + ${}^{24}{Mg}$ saturates at ∼ 1100 mb, while that for ${}^{16}O$ + ${}^{26}{Mg}$ and ${}^{18}O$ + ${}^{24}{Mg}$ reaches ∼ 1200 mb. The fusion cross section excitation functions can be well described by the model of Glas and Mosel using reasonable parameters; the model of Bass reproduces the data well above $E_{c . m .} \approx 25$ MeV but overpredicts the cross section below this energy.

NUCLEAR REACTIONS ${}^{16}O$ + ${}^{24}{Mg}$ , $E_{lab} = 30 - 81$ MeV; ${}^{16}O$ + ${}^{26}{Mg}$ , $E_{lab} = 29.4 - 81$ MeV; ${}^{18}O$ + ${}^{24}{Mg}$ , $E_{lab} = 32 - 72$ MeV; measured $σ_{fusion}$ ; measured $σ (θ)$ elastic scattering; deduced optical-model parameters.

Inclusive pion production in relativistic proton collisions with nuclei, a reexamination

Rubin H. Landau

Phys. Rev. C 17, 2144 (1978) - Published 1 June, 1978

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Various data for the $pA \to π^{\pm} X$ reaction are examined with emphasis on viewing these data in a light most useful for understanding $π$ production in heavy ion collisions. The 730 MeV (proton energy) results of Cochrane et al. are found to display a large amount of scaling—if plotted as a function of the Feynman variable $x_{R}$ and if the $k_{⊥}$ behavior is removed. Viewed in this matter, the larger $x_{R}$ behavior of the 730 MeV data agree well with the 1-5 GeV data of Papp et al. In the forward hemisphere $π$ production from nuclei appears simply related to nucleon-nucleon $π$ production and is consistent with the limiting behavior of hard collision models. In the backward hemisphere, there is evidence for nuclear structure effects and clustering phenomena not included in hard collision models.

NUCLEAR REACTIONS Inclusive pion production, $E = 730$ MeV-5 GeV protons, Feynman variable.

Consequences of wave function orthogonality for medium energy nuclear reactions

J. V. Noble

Phys. Rev. C 17, 2151 (1978) - Published 1 June, 1978

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In the usual models of high-energy bound-state to continuum transitions no account is taken of the orthogonality of the bound and continuum wave functions. This orthogonality induces considerable cancellations in the overlap integrals expressing the transition amplitudes for reactions such as ( $e, e^{'} p$ ), ( $γ, p$ ), and ( $π, N$ ), which are simply not included in the distorted-wave Born-approximation calculations which to date remain the only computationally feasible heirarchy of approximations. The object of this paper is to present a new formulation of the bound-state to continuum transition problem, based upon flux conservation, in which the orthogonality of wave functions is taken into account ab initio. The new formulation, while exact wave functions are used, offers the possibility of using approximate wave functions for the continuum states without doing violence to the cancellations induced by orthogonality. The method is applied to single-particle states obeying the Schrödinger and Dirac equations, as well as to a coupled-channel model in which absorptive processes can be described in a fully consistent manner. Several types of absorption vertex are considered, and in the ( $π, N$ ) case the equivalence of pseudoscalar and pseudovector $π NN$ coupling is seen to follow directly from wave function orthogonality.

NUCLEAR REACTIONS Orthogonality constraints on bound-continuum transitions. Applied to Schrödinger, Dirac, and coupled-channel wave functions, describing ( $e, e^{'} p$ ), ( $γ, p$ ) and ( $π, N$ ) reactions on nuclei at medium energies. New form of DWBA. Equivalence of pseudoscalar and pseudovector coupling in ( $π, N$ ). Relativistic corrections vs high momentum components in ( $γ, p$ ).

Photoproduction of neutral pions near threshold from three-body targets

P. Bosted and J. M. Laget

Phys. Rev. C 17, 2159 (1978) - Published 1 June, 1978

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Proton states in the $Z = 99$ nucleus ${}^{251}{Es}$ excited by ${}^{251}{Fm}$ electron capture decay and ${}^{250}{Cf} (α, t)$ reaction

I. Ahmad, R. K. Sjoblom, A. M. Friedman, and S. W. Yates

Phys. Rev. C 17, 2163 (1978) - Published 1 June, 1978

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Level structure of the $Z = 99$ nucleus, ${}^{251}{Es}$ , has been investigated by measuring the $γ$ rays and conversion electrons associated with the electron capture decay of 5.3-h ${}^{251}{Fm}$ , and from triton spectra produced in the ${}^{250}{Cf} (α, t) {}^{251}{Es}$ reaction. The $γ$ -ray spectra were measured with a 2- ${cm}^{2}$ × 5-mm planar and a 25- ${cm}^{3}$ coaxial Ge(Li) detector and the electron spectra were measured with a cooled Si(Li) detector. Fortyfive $γ$ rays were identified in ${}^{251}{Es}$ and the multipolarities of most of the transitions were deduced. $Log ft$ values for the observed electron capture transitions were derived from the measured electron capture transition intensities. A two-parameter $γ - γ$ coincidence experiment was performed to determine the relationships between various $γ$ transitions. Triton spectra from the ${}^{250}{Cf} (α, t) {}^{251}{Es}$ reaction were analyzed with an Enge split-pole magnetic spectrograph. On the basis of the present investigation the following intrinsic states were identified in ${}^{251}{Es}$ : 3/2 - [521], 0; 7/2 + [633], 8.3; 1/2 - [521], 411; 7/2 - [514], 461.4; 9/2 + [624], 777.9; ${7 / 2 + [633] \otimes 2 +}_{11 / 2 +}$ vibrational state, 889.1; ${n [734] \frac{9}{2} -; n [620] \frac{1}{2} +; p [521] \frac{3}{2} -}_{\frac{11}{2} +}$ three-quasiparticle state, 1239.0 keV. A $K π = \frac{11}{2} +$ state at 1264.9 keV was interpreted as a three-quasiparticle state but could not be given a definite assignment. This is the first time a definite identification of the proton orbitals 1/2 - [521] and 7/2 - [514] has been made in any nucleus.

RADIOACTIVITY ${}^{251}{Fm}$ [from ${}^{249}{Cf} (α, 2 n)$ ]; measured $E_{γ}$ , $I_{γ}$ , $E_{ce}$ , $I_{ce}$ , $γ γ$ coin, $α$ branching.

NUCLEAR REACTIONS ${}^{250}{Cf} (α, t)$ , $E = 28.0$ MeV; measured $E$ (excitation), $σ$ . ${}^{251}{Es}$ deduced levels, $log f t (EC)$ , $γ$ multipolarity, $I$ , $π$ , five single-particle states, one vibrational state, and two three-quasiparticle states. Mass-separated ${}^{251}{Fm}$ and ${}^{250}{Cf}$ .

Mass and $β$ decay of the new neutron-rich isotope ${}^{60}{Mn}$

Eric B. Norman, Cary N. Davids, Martin J. Murphy, and Richard C. Pardo

Phys. Rev. C 17, 2176 (1978) - Published 1 June, 1978

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The new isotope ${}^{60}{Mn}$ was produced by bombarding ${}^{48}{Ca}$ with ${}^{18}O$ ions at $E_{{}^{18}O} = 50 - 70$ MeV. The $β$ -decay scheme of ${}^{60}{Mn}$ was determined from $γ$ -ray singles and $γ - γ$ coincidence experiments using large Ge(Li) detectors. The half life of ${}^{60}{Mn}$ was found to be 1.79 ± 0.10 s. A new level with excitation energy 2792 keV was observed in the daughter, ${}^{60}{Fe}$ . The ground-state spin and parity of ${}^{60}{Mn}$ was determined to be $3^{+}$ and its total decay energy $Q_{β}$ was measured to be 8.51 ± 0.10 MeV. This corresponds to a mass excess of - 52.89 ± 0.10 MeV, which is compared with various predictions. The structure of ${}^{60}{Fe}$ as determined from the present work and from previous experiments is compared with a shell-model calculation.

RADIO ACTIVITY ${}^{60}{Mn}$ : measured $T_{\frac{1}{2}}$ , $E_{γ}$ , $I_{γ}$ , $E_{β}$ , $γ - γ$ coin, $β - γ$ coin; deduced decay scheme, $log ft$ , mass excess, g.s. $J^{π}$ . ${}^{60}{Fe}$ : deduced levels. Enriched targets, Ge(Li) detectors, plastic scintillator, multiple rabbit.

Identification of ${}^{147}{Cs}$ and half-life determinations for Cs and Ba isotopes with $A = 144 - 147$ and Rb and Sr isotopes with $A = 96 - 98$

F. K. Wohn, K. D. Wünsch, H. Wollnik, R. Decker, G. Jung, E. Koglin, and G. Siegert

Phys. Rev. C 17, 2185 (1978) - Published 1 June, 1978

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Half-life determinations of Rb and Cs fission products available at an on-line mass separator have been made for several neutron-rich Rb, Sr, Cs, and Ba isotopes using both $β$ -multiscale and $γ$ -multispectra measurements. The half-lives and rms uncertainties (in sec) are ${}^{96}{Rb}$ , 0.203 ± 0.004; ${}^{96}{Sr}$ , 1.015 ± 0.019; ${}^{97}{Rb}$ , 0.170 ± 0.002; ${}^{97}{Sr}$ , 0.441 ± 0.015; ${}^{98}{Rb}$ , 0.108 ± 0.005; ${}^{98}{Sr}$ , 0.66 ± 0.07; ${}^{144}{Cs}$ , 1.02 ± 0.04; ${}^{144}{Ba}$ , 12.3 ± 0.4; ${}^{145}{Cs}$ , 0.590 ± 0.020; ${}^{145}{Ba}$ , 4.31 ± 0.16; ${}^{146}{Cs}$ , 0.305 ± 0.010; ${}^{146}{Ba}$ , 2.18 ± 0.11; ${}^{147}{Cs}$ , 0.218 ± 0.009; ${}^{147}{Ba}$ , 0.70 ± 0.06. This work provides an unambiguous identification of the new neutron-rich isotope ${}^{147}{Cs}$ . The half-life values are compared with predictions of the gross theory of $β$ decay and an apparent shell effect at $N = 58$ on the half-lives of neutron-rich isotopes of Kr, Rb, Sr, Y, and Zr is discussed.

RADIOACTIVITY ${}^{96, 97, 98}{Rb}$ , ${}^{96, 97, 98}{Sr}$ , ${}^{144, 145, 146, 147}{Cs}$ , ${}^{144, 145, 146, 147}{Ba}$ [from ${}^{235}U (n, fission)$ ]; measured $T_{\frac{1}{2}}$ . Ge(Li) and plastic scintillation detectors. Mass-separated Rb and Cs activities.

Decay of neutron-rich ${}^{45}{Ar}$ and ${}^{46}{Ar}$

R. F. Petry, D. G. Shirk, John C. Hill, and K. H. Wang

Phys. Rev. C 17, 2197 (1978) - Published 1 June, 1978

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The decay of ${}^{45}{Ar}$ and the previously unreported decay of ${}^{46}{Ar}$ have been studied from sources prepared in the ${}^{48}{Ca} (n, 2 p, 2 n) {}^{45}{Ar}$ and ${}^{48}{Ca} (n, 2 pn) {}^{46}{Ar}$ reactions. The half-lives of ${}^{45}{Ar}$ and ${}^{46}{Ar}$ were measured to be 20.8 and 8.9 sec, respectively. On the basis of results from $γ$ spectroscopy levels in ${}^{45}K$ and ${}^{46}K$ are determined. Of 14 $γ$ rays observed in the decay of ${}^{45}{Ar}$ , 13 are placed in a ${}^{45}K$ level scheme. The only $γ$ ray observed in ${}^{46}{Ar}$ decay is one from a $1^{+}$ core state in ${}^{46}K$ at 1944 keV. The systematics of K nuclei are discussed.

RADIOACTIVITY ${}^{45}{Ar}$ [from ${}^{48}{Ca} (n, 2 p 2 n)$ ], ${}^{46}{Ar}$ [from ${}^{48}{Ca} (n, 2 pn)$ ] medium energy neutrons; measured $T_{\frac{1}{2}}$ , $E_{γ}$ , $I_{γ}$ ; ${}^{45}K$ and ${}^{46}K$ deduced levels, $J$ , $π$ , $log ft$ . Enriched targets, radiochemistry, Ge(Li) detectors.

Comparison of methods for calculating decay lifetimes

W. Tobocman

Phys. Rev. C 17, 2205 (1978) - Published 1 June, 1978

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A simple scattering model is used to test alternative methods for calculating decay lifetimes, or equivalently, resonance widths. We consider the scattering of $s$ -wave particles by a square well with a square barrier. Exact values for resonance energies and resonance widths are compared with values calculated from Wigner-Weisskopf perturbation theory and from the Garside-MacDonald projection operator formalism. The Garside-MacDonald formalism gives essentially exact results while the predictions of the Wigner-Weisskopf formalism are fairly poor.

RADIOACTIVITY Methods for calculating lifetime for decay by barrier penetration tested on a soluble model.

Angular correlation measurements in the decay of ${}^{71}{Zn}^{m}$

K. S. Krane

Phys. Rev. C 17, 2213 (1978) - Published 1 June, 1978

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The anisotropies of 15 $γ - γ$ angular correlations in ${}^{71}{Ga}$ following the decay of 3.9-h ${}^{71}{Zn}^{m}$ have been measured. The results are discussed in terms of the spin assignments of the ${}^{71}{Ga}$ levels and the $\frac{E 2}{M 1}$ multipole mixing ratios of the ${}^{71}{Ga}$ $γ$ transitions.

RADIOACTIVITY ${}^{71}{Zn}^{m}$ [from ${}^{70}{Zn} (n, γ)$ ]; measured $γ γ (θ)$ . ${}^{71}{Ga}$ deduced $J$ , $π$ , $δ (\frac{E 2}{M 1})$ .

Superallowed Fermi beta transition of ${}^{62}{Ga}$

R. Chiba, S. Shibasaki, T. Numao, H. Yokota, S. Yamada, K. Kotajima, S. Itagaki, S. Iwasaki, T. Takeda, and T. Shinozuka

Phys. Rev. C 17, 2219 (1978) - Published 1 June, 1978

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A superallowed Fermi $β$ transition ( $J^{π} = 0^{+}, T = 1$ ) from ${}^{42}{Ga} (A = 4 n + 2)$ has been identified. The measured half-life and $β$ ray end point energy are $T_{\frac{1}{2}} = 116.4 \pm 1.5$ msec and $E_{β max} = 8.3 \pm 0.3$ MeV, respectively. The $Ft$ value for the transition has been evaluated with the measured half-life and estimated $β$ ray end point energy from a phenomenological analysis of the Coulomb displacement energies of isobaric analog states. The obtained value is $F t = f t (1 + δ_{R}) (1 - δ_{C}) = 3103 \pm 44$ sec which turns out to be 0.6% larger than that expected for such $0^{+}$ - $0^{+}$ superallowed β transitions.

RADIOACTIVITY ${}^{62}{Ga}$ [from ${}^{64}{Zn} (p, 3 n)$ ]; measured $T_{\frac{1}{2}}$ $E_{β max}$ ; deduced $Δ E_{C}$ , $F t$ value.

Alpha particle transfer in the interacting boson approximation

C. L. Bennett and H. W. Fulbright

Phys. Rev. C 17, 2225 (1978) - Published 1 June, 1978

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The interacting boson approximation of Iachello and Arima has been applied to the calculation of $α$ particle transfer spectroscopic factors for nuclei from ${}^{44}{Ti}$ to ${}^{68}{Zn}$ . The results are compared with the results of ( ${}^{6}{Li}, d$ ) experiments in the same mass region.

NUCLEAR STRUCTURE Calculated $α$ spectroscopic factors; compared with experimental ( ${}^{6}{Li}, d$ ) $S$ values.

Spins of ${}^{47}V$ and ${}^{48}V$ by the atomic beam magnetic resonance method

O. Redi

Phys. Rev. C 17, 2229 (1978) - Published 1 June, 1978

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The atomic beam magnetic resonance technique has been used to measure the spins of ${}^{47}V$ (33 min) and ${}^{48}V$ (16 days). The spin values are: ${}^{47}V$ , $I = \frac{3}{2} and {}^{48}V$ , $I = 4$ . These results are compared with the available nuclear structure calculations. Recalculations of the level scheme of ${}^{47}V$ using the pure $f_{\frac{7}{2}}$ model of McCullen, Bayman, and Zamick, with revised two-body matrix elements for the residual interaction are reported. Agreement is found with the experimentally observed ${15 / 2}^{-}$ state of ${}^{47}V$ .

NUCLEAR STRUCTURE ${}^{47, 48}V$ ; measured $J$ , Atomic-beam magnetic resonance. ${}^{47}V$ calculated levels, Pure $f_{\frac{7}{2}}$ model.

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Decays of the lowest $T = 2$ state in ${}^{44}{Ti}$

Inhibited electric-quadrupole transitions in odd-neutron spherical nuclei

Relativistic two-fluid model of nucleus-nucleus collisions

Observation of intermediate structure resonances in the ${}^{12}C$ ( ${}^{16}O$ , ${}^{16}O$ ( $0^{+}$ , 6.05)) reaction

Localization of various reaction processes for weakly bound heavy projectiles

Recoil distance lifetime measurements in ${}^{69}{As}$ and ${}^{72}{Se}$

Two theoretical potential models and the elastic scattering of ${}^{16}O$ from ${}^{63, 65}{Cu}$ at 40-46 MeV

Complete fusion of ${}^{16, 18}O$ with ${}^{24, 26}{Mg}$

Inclusive pion production in relativistic proton collisions with nuclei, a reexamination

Consequences of wave function orthogonality for medium energy nuclear reactions

Photoproduction of neutral pions near threshold from three-body targets

Proton states in the $Z = 99$ nucleus ${}^{251}{Es}$ excited by ${}^{251}{Fm}$ electron capture decay and ${}^{250}{Cf} (α, t)$ reaction

Mass and $β$ decay of the new neutron-rich isotope ${}^{60}{Mn}$

Identification of ${}^{147}{Cs}$ and half-life determinations for Cs and Ba isotopes with $A = 144 - 147$ and Rb and Sr isotopes with $A = 96 - 98$

Decay of neutron-rich ${}^{45}{Ar}$ and ${}^{46}{Ar}$

Comparison of methods for calculating decay lifetimes

Angular correlation measurements in the decay of ${}^{71}{Zn}^{m}$

Superallowed Fermi beta transition of ${}^{62}{Ga}$

Alpha particle transfer in the interacting boson approximation

Spins of ${}^{47}V$ and ${}^{48}V$ by the atomic beam magnetic resonance method

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