Recent Articles

Singular cores in the three-body problem. III. Unique equations

D. D. Brayshaw

Phys. Rev. C 13, 1835 (1976) - Published 1 May, 1976

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Three-particle scattering theory is reexamined for interactions which contain singular cores in a finite number of two-body partial waves. It is shown that the Faddeev equations do not possess a unique solution for the corresponding $t$ matrix, and hence, cannot be used directly to examine "realistic" singular core models of the $N - N$ interaction. For the special case of a pure boundary condition model, alternative one-dimensional equations are derived based on the Schrödinger and Faddeev representations. These are shown to be completely equivalent, and to uniquely specify the three-body observables. The Faddeev version is shown to be a special case of the author's boundary condition formalism. Equations suitable for realistic models which include potential tails are presented.

NUCLEAR REACTIONS Three-body equations, singular core interactions.

Stripping channel contribution to the nonlocality of the deuteron optical potential

S. N. Mukherjee, S. Pal, D. K. Srivastava, and N. K. Ganguly

Phys. Rev. C 13, 1849 (1976) - Published 1 May, 1976

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It is shown that the effect of coupling $l = 1$ stripping channels to the incident deuteron channel is to produce a nonlocality in the $d - {}^{48}{Ca}$ optical potential which gives the right type of energy dependence for the equivalent local optical potential.

NUCLEAR REACTIONS ${}^{48}{Ca} (d, d)$ , $E = 4.0 - 16.0$ MeV; calculated $σ (E, θ)$ , obtained energy dependent $d - {}^{48}{Ca}$ optical potential.

Photonuclear reactions in ${}^{90}{Zr}$

D. Brajnik, D. Jamnik, G. Kernel, M. Korun, U. Miklavžič, B. Pucelj, and A. Stanovnik

Phys. Rev. C 13, 1852 (1976) - Published 1 May, 1976

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Photonuclear reactions in ${}^{90}{Zr}$ were studied in the excitation region of the giant dipole resonance. Experimental results which include all the most important reaction channels consist of cross sections integrated over angles, and for photoprotons, of additional data on angular distributions. Photoproton cross sections were determined by a least-squares-fit analysis of proton spectra resulting from a series of irradiations with bremsstrahlung of different end-point energies. In addition to the ground state ${}^{90}{Zr} (γ, p_{0}) {}^{89}Y_{g . s .}$ , photoproton cross-section data for three groups of ${}^{89}Y$ excited states are presented. Other results which consist of cross sections for reactions ( $γ, p_{1}$ ), ( $γ, n_{1}$ ), ( $γ, 2 n$ ), ( $γ, np$ ), and ( $γ, n$ ) were obtained through different techniques based on the measurement of activation yields. It is shown that 70% of the total photoproton cross section is due to the transition to the ground, the 1.74 MeV, and possibly the 1.51 MeV states of ${}^{89}Y$ . The photoneutron cross section is dominated by the contribution involving the first excited state and all those states of ${}^{89}{Zr}$ which subsequently decay to it. Experimental data are interpreted in terms of isospin splitting of the giant dipole resonance. In the total photoproton cross section, apart from a broad resonance at 16 MeV similar to the dominant structure of the ( $γ, n$ ) reaction, an additional resonance of approximately the same magnitude appears at 20.5 MeV. The latter resonance is attributed to the $T_{>}$ part of the giant dipole resonance. Its integrated cross section of about 8% of the total photonuclear cross section accounts for the main part of the expected $T_{>}$ strength. Neutron channels do not seem to contribute significantly to the decay of the $T_{>}$ resonance. It is concluded from ( $γ, np$ ) and ( $γ, 2 n$ ) reactions that the $T_{>}$ resonance is superimposed on a $T_{<}$ background extending to higher energies.

NUCLEAR REACTIONS ${}^{90}{Zr} (γ, p)$ , ( $γ, n$ ), ( $γ, n p$ ) and ( $γ, 2 n$ ), $E_{γ} = 12 - 30$ MeV; measured photoproton spectra and bremsstrahlung activation yields; deduced $σ (E, ϑ)$ and $σ (E)$ .

Photoneutron spectrum of lead following excitation by 8999, 8533, and 8120 keV photons

J. E. McFee, W. V. Prestwich, and T. J. Kennett

Phys. Rev. C 13, 1864 (1976) - Published 1 May, 1976

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The photoneutron spectrum of natural lead has been observed for photoexcitation energies of 8999, 8533, and 8120 keV using a high-resolution ${}^{3}{He}$ ionization chamber. The photons were obtained from the ( $n, γ$ ) reaction on a nickel target positioned in a nuclear reactor. The $Q$ values for the three reactions ${}^{208}{Pb} (γ, n) {}^{207}{Pb}$ , ${}^{207}{Pb} (γ, n) {}^{206}{Pb}$ , and ${}^{206}{Pb} (γ, n) {}^{205}{Pb}$ have been determined and are, respectively, 7369 ± 5, 6743 ± 3, and 8087 ± 3 keV. Neutron groups corresponding to different final states following excitation by one of the three photon components have been observed and their partial cross sections are reported. The distribution and some systematics of the neutron reduced widths have been studied. The absolute cross sections of the reaction ${}^{208}{Pb} (γ, n) {}^{207}{Pb}$ at 8999 and 8533 keV photon energies have been found to be 6.8 ± 2.9 and 5.0 ± 2.1 mb, respectively.

NUCLEAR REACTIONS ${}^{206, 207, 208}{Pb} (γ, n)$ , $E = 8.120, 8.533, 8.999$ MeV; measured $σ (E; E_{n})$ . Deduced $Q$ , reduced widths.

${}^{45}{Sc} (α, d) {}^{47}{Ti}$ reaction

Gerald Hardie, L. Meyer-Schützmeister, David Gloeckner, and T. H. Braid

Phys. Rev. C 13, 1874 (1976) - Published 1 May, 1976

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Using a split-pole magnetic spectrograph, the ${}^{45}{Sc} (α, d) {}^{47}{Ti}$ reaction was studied at $E (α) = 25$ Mev and with a range of angles from 7° to 50°. These measurements are compared with results we obtained using the ${}^{45}{Sc} ({}^{3}{He}, p) {}^{47}{Ti}$ reaction. One result of this comparison is the identification of candidates for states with high spin. The major emphasis of this paper is the study of such states. Two-particle spectroscopic amplitudes are calculated using an ${(f_{\frac{7}{2}})}^{7}$ model, assuming an inert ${}^{40}{Ca}$ core. Zero-range distorted-wave Born-approximation calculations are then performed with these amplitudes. A comparison between these shell-model calculations and the experimental results indicates that the states at 4.506 and 3.583 MeV have $J^{π}' s$ of ${19 / 2}^{-}$ and ${17 / 2}^{-}$ . A second result of the comparison between the ( $α, d$ ) and ( ${}^{3}{He}, p$ ) reactions concerns the nature of the 3.22-MeV state in ${}^{47}{Ti}$ . It is strongly populated with an orbital angular momentum transfer of 0 by the ( ${}^{3}{He}, p$ ) reaction and only weakly populated by the ( $α, d$ ) reaction, suggesting that it is formed by the transfer of a neutron-proton pair with $S = 0$ , $T = 1$ . This is similar to the transfer forming the state at 7.346 MeV, the analog of the ${}^{47}{Sc}$ ground state.

NUCLEAR REACTIONS ${}^{45}{Sc} (α, d)$ , $E = 25$ MeV; measured $σ (θ)$ . ${}^{47}{Ti}$ deduced levels, $J$ , $π$ . Shell model and DWBA analyses.

Neutron resonance spectroscopy: ${}^{139}{La}$

G. Hacken, J. Rainwater, H. I. Liou, and U. N. Singh

Phys. Rev. C 13, 1884 (1976) - Published 1 May, 1976

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Results of high resolution neutron time of flight spectroscopy measurements on natural lanthanum (99.9% ${}^{139}{La}$ ) are presented. Plots of $σ_{t}$ vs $E$ are given to 76 keV. Values of $E_{0}$ and $g Γ_{n}^{0}$ are presented for all 150 ${}^{139}{La}$ levels observed to 26 keV. About 50 of these levels are probably $p$ levels, based on Bayes' theorem and the minimum $g Γ_{n}$ for detection vs $E$ . Intermediate structure seems to be present in $S_{0} \equiv Σ \frac{g Γ_{n}^{0}}{Δ E}$ . From 6 to 18 keV, $10 {}^{4}S_{0} \approx 0.50$ . Two strong levels at 3 and 3.5 keV, and several strong levels in the 18.5 to 26 keV region, boost $S_{0}$ to a value $10 {}^{4}S_{0} = 0.76$ for the full 26 keV range. A standard analysis that ignores intermediate structure and uses a single channel Porter-Thomas fit to the entire $g Γ_{n}^{0}$ population yields $10 {}^{4}S_{0} = 0.76 \pm 0.13$ , $D_{0} = 208 \pm 10$ eV, and $10 {}^{4}S_{1} = ({0.6}_{- 0.2}^{+ 0.3})$ .

NUCLEAR REACTIONS ${}^{139}{La} (n, total)$ , $E = 3 eV - 76 keV$ ; measured $σ_{t} (E)$ to 76 keV; deduced resonance $E_{0}$ , $g Γ_{n}^{0}$ , $D_{0}$ , $S_{0}$ , $S_{1}$ .

Recoil-distance lifetime measurements of states in ${}^{47}V$ and ${}^{47}{Ti}$ induced by heavy-ion reactions

M. Toulemonde, N. Schulz, J. C. Merdinger, and P. Engelstein

Phys. Rev. C 13, 1889 (1976) - Published 1 May, 1976

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The recoil-distance method has been used in conjunction with heavy-ion reactions to measure the following mean lives: $τ = 1.23 \pm 0.16 and 0.63 \pm 0.13$ ns for the 88-keV ${5 / 2}^{-}$ and 146-keV ${7 / 2}^{-}$ states in ${}^{47}V$ , and $τ = 314 \pm 22$ ps for the 160-keV ${7 / 2}^{-}$ state in ${}^{47}{Ti}$ .

NUCLEAR REACTIONS ${}^{31}P ({}^{19}F, p 2 n γ) ({}^{19}F, n 2 p γ)$ $E = 47$ MeV; measured recoil distance. ${}^{47}V$ , ${}^{47}{Ti}$ levels deduced $T_{\frac{1}{2}}$ , $B (M 1)$ , $B (E 2)$ . Natural target, Ge(Li) detector.

Elastic scattering of ${}^{84}{Kr}$ by ${}^{208}{Pb}$

R. Vandenbosch, M. P. Webb, T. D. Thomas, S. W. Yates, and A. M. Friedman

Phys. Rev. C 13, 1893 (1976) - Published 1 May, 1976

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Angular distributions for the elastic scattering of ${}^{84}{Kr}$ by ${}^{208}{Pb}$ at 494, 510, and 718 MeV have been measured. Fresnel, parametrized phase shift, and optical model analyses show that Coulomb deflection and surface absorption effects dominate. The optical model analysis shows that the results are sensitive to the nuclear potential only in the vicinity of the strong absorption radius, giving a value of the nuclear potential at this distance that is in agreement with a number of theoretical estimates.

NUCLEAR REACTIONS ${}^{208}{Pb}$ ( ${}^{84}{Kr}$ , ${}^{84}{Kr}$ ), $E = 494, 510, and 718$ MeV; measured $σ (θ)$ ; Fresnel, parametrized phase shift and optical model analyses.

Properties of high-spin states in ${}^{91}{Nb}$ and ${}^{91}{Zr}$ via ${}^{6}{Li}$ -induced reactions

B. A. Brown, P. M. S. Lesser, and D. B. Fossan

Phys. Rev. C 13, 1900 (1976) - Published 1 May, 1976

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The properties of high-spin states in ${}^{91}{Nb}$ and ${}^{91}{Zr}$ have been studied with the ${}^{88}{Sr} ({}^{6}{Li}, 3 n) {}^{91}{Nb}$ and ${}^{88}{Sr} ({}^{6}{Li}, p 2 n) {}^{91}{Zr}$ reactions. In-beam measurements with Ge(Li) and Si(Li) detectors of $γ$ -ray excitation functions, $γ - γ$ coincidences, $γ$ -ray angular distributions, and pulsed beam- $γ$ timing spectra were made to establish decay schemes, level energies, spin-parity assignments, $γ$ -ray multipolarities, and isomeric lifetimes. All of the high-spin states involving the $π 1 g_{\frac{9}{2}}$ , $π 2 p_{\frac{1}{2}}$ , and $ν 2 d_{\frac{5}{2}}$ orbitals as well as other more complicated states were identified. In particular, the theoretically predicted isomeric states in ${}^{91}{Nb}$ and ${}^{91}{Zr}$ were found: the $| {(1 g_{\frac{9}{2}})}^{2} 2 p_{\frac{1}{2}}, {\frac{17}{2}}^{-} 〉$ state in ${}^{91}{Nb}$ is at 2035 keV with a $τ = 5.42 \pm 0.18$ μsec, and the $| {(1 g_{\frac{9}{2}})}^{2} 2 d_{\frac{5}{2}}, {\frac{21}{2}}^{+} 〉$ state in ${}^{91}{Zr}$ is at 3167 keV with a $τ = 6.28 \pm 0.20$ μsec. The experimental energy levels and $B (E 2)$ values obtained for these nuclei as well as those of other $N = 50 and 51$ nuclei are compared with recent theoretical work of Gloeckner et al. The $E 2$ effective charges for the mass-90 region are discussed.

NUCLEAR REACTIONS ${}^{88}{Sr} ({}^{6}{Li}, 3 n)$ , ${}^{88}{Sr} ({}^{6}{Li}, p 2 n)$ , $E = 34$ MeV, pulsed beam; measured $γ - γ$ coincidence; deduced levels in ${}^{91}{Nb}$ and ${}^{91}{Zr}$ ; measured $γ (E, θ, t)$ ; deduced $J^{π}$ , $T_{\frac{1}{2}}$ , branching ratio, $δ (\frac{E 2}{M 1})$ , $B (E 2)$ , effective charges. Natural target, Ge(Li) and Si(Li) detectors.

High-spin states in ${}^{42}{Ca}$

R. L. Robinson, H. J. Kim, J. B. McGrory, G. J. Smith, W. T. Milner, R. O. Sayer, J. C. Wells, Jr., and J. Lin

Phys. Rev. C 13, 1922 (1976) - Published 1 May, 1976

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Levels in ${}^{42}{Ca}$ excited by the ${}^{28}{Si} ({}^{16}O, 2 p)$ reaction have been investigated with $E_{{}^{16}O} = 36 - 42$ MeV. $γ$ -ray angular distributions and $γ γ$ angular correlations relative to the beam direction have been determined. Level energies, decay modes, spins, parities, and $γ$ -ray radiative admixtures were extracted. Level energies in keV and preferred $J^{π}' s$ are: 4099.9 ( $5^{-}$ ), 5491.4 ( $5^{+}$ ), 5744.1 ( $5^{-}$ ), 6144.5 ( $6^{+}$ ), 6408.8 ( $7^{+}$ ), 6553.9 ( $7^{-}$ ), 7368.7 ( $6^{-}$ or $8^{-}$ ), and 8297.9 ( $J = J_{7369} \pm 1$ ). These spin-parity assignments differ from those reported recently by Warburton, Kolata, and Olness.

NUCLEAR REACTIONS ${}^{28}{Si} ({}^{16}O, 2 p)$ $E = 36 - 42$ MeV; measured $E_{γ}$ , $I_{γ}$ , $γ (θ)$ , $γ γ (θ)$ . ${}^{42}{Ca}$ deduced levels, $J$ , $π$ , $δ$ , $γ$ branching, transition probabilities.

Nuclear structure study of ${}^{141}{Nd}$ , ${}^{143}{Nd}$ , and ${}^{143}{Pm}$ by ${}^{13}C$ -induced reactions on ${}^{142}{Nd}$

S. T. Thornton, T. C. Schweizer, D. E. Gustafson, J. L. C. Ford, Jr., and M. J. LeVine

Phys. Rev. C 13, 1936 (1976) - Published 1 May, 1976

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Angular distributions at a bombarding energy of 67.5 MeV were measured for the ${}^{142}{Nd}$ ( ${}^{13}C$ , ${}^{14}C$ ) ${}^{141}{Nd}$ , ${}^{142}{Nd}$ ( ${}^{13}C$ , ${}^{12}C$ ) ${}^{143}{Nd}$ , and ${}^{142}{Nd}$ ( ${}^{13}C$ , ${}^{12}B$ ) ${}^{143}{Pm}$ reactions. Spectroscopic factors were obtained by comparing finite-range recoil distorted-wave Born-approximation calculations with the data. Spin assignments were made for the nucleus ${}^{141}{Nd}$ . The usefulness of heavy-ion induced transfer reactions in preferentially populating high spin states in the final nucleus is discussed. The distorted-wave Born-approximation predictions are shown to be in good agreement with the experimental angular distributions except in cases of poor angular momentum matching in the entrance and exit channels.

NUCLEAR REACTIONS ${}^{142}{Nd}$ ( ${}^{13}C$ , ${}^{14}C$ ), ( ${}^{13}C$ , ${}^{12}C$ ), ( ${}^{13}C$ , ${}^{12}B$ ), $E = 67.5$ MeV; measured $σ (E_{c}, θ)$ . ${}^{141}{Nd}$ , ${}^{143}{Nd}$ , ${}^{143}{Pm}$ levels, assigned $J^{π}$ , deduced $C^{2} S$ , DWBA analyses. Enriched target. Resolution 70 keV; $θ_{lab} = 30 ° - 75 °$ , $Δ θ = 3 °$ .

Investigation of high-spin states in ${}^{38}{Ar}$

J. J. Kolata, J. W. Olness, E. K. Warburton, and A. R. Poletti

Phys. Rev. C 13, 1944 (1976) - Published 1 May, 1976

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The high-spin states formed in ${}^{38}{Ar}$ following the fusion of ${}^{14}N$ , ${}^{16, 18}O$ , and ${}^{19}F$ projectiles with targets of ${}^{26}{Mg}$ , ${}^{27}{Al}$ , and ${}^{28}{Si}$ have been investigated. Angular distribution, linear polarization, and $γ - γ$ coincidence data on the $γ$ rays emitted by these states were utilized to construct a decay scheme for ${}^{38}{Ar}$ , and to suggest probable spin-parity assignments for several new high-spin states. Results of lifetime measurements for several of these states are presented, and a comparison of the experimental level energies to the predictions of a simple weak-coupling calculation and a large-basis shell model calculation is given.

NUCLEAR REACTIONS ( $HI, x n, y p, z α$ ) studies for ${}^{38}{Ar}$ ; ${}^{14}N$ , ${}^{16, 18}O$ , ${}^{19}F$ projectiles, ${}^{26}{Mg}$ , ${}^{27}{Al}$ , ${}^{28}{Si}$ targets, $E = 40$ MeV; measured $γ γ$ coin.; deduced levels in ${}^{38}{Ar}$ ; measured $σ (E_{γ}, θ)$ and $P_{γ}$ ; deduced $J^{π}$ for high-spin levels; measured recoil distance; deduced $T_{\frac{1}{2}}$ . Natural and isotopically separated targets, Ge(Li) detectors. Compared results to shell-model and weak-coupling-model calculations.

Angular distributions of specific gamma rays emitted in the deexcitation of prompt fission products of ${}^{252}{Cf}$

A. Wolf and E. Cheifetz

Phys. Rev. C 13, 1952 (1976) - Published 1 May, 1976

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Angular distributions of specific $γ$ rays emitted in the deexcitation of prompt fission products of ${}^{252}{Cf}$ were measured with respect to the fission direction. A total of 42 angular distributions were measured, 23 of which were of transitions in even-even fragments. The strong anisotropy ( $A_{2} = 0.4 - 0.6$ ) measured for $2^{+}$ → $0^{+}$ , $4^{+}$ → $2^{+}$ , and $6^{+}$ → $4^{+}$ transitions in ${}^{138, 140}{Xe}$ and ${}^{142, 144}{Ba}$ provides direct evidence that the angular momentum of the primary fragments is completely aligned perpendicular to the fission axis. Most of the results are consistent with the results of a statistical calculation. The anisotropies measured for some transitions in even-odd fragments were combined with information of other authors in an attempt to determine spins of low-lying levels in these fragments. Finally, it is shown that about 60% of the anisotropy of the gross unresolved $γ$ -ray spectrum, measured extensively by other authors, is due to transitions in the ground-state band of even-even fragments.

RADIOACTIVITY, FISSION ${}^{252}{Cf} (sf)$ ; measured $σ (θ)$ of $γ$ from fragments; Ge(Li) detector, 0.8 keV at 122 keV.

Interaction of 0.6-300 GeV protons with U, Bi, Au, and Ag; mica track detector study

J. Hudis and S. Katcoff

Phys. Rev. C 13, 1961 (1976) - Published 1 May, 1976

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Mica track detectors were utilized to investigate interactions of 0.6-300 GeV protons with U, Bi, Au, and Ag. Fission cross sections of heavy elements are shown to remain nearly constant as the incident proton energy is increased from 13 to 300 GeV. The values of $σ_{f}$ for U, Bi, Au, and Ag at 300 GeV are 890 ± 130, 181 ± 35, 118 ± 24, and ∼1.3 mb, respectively. There is also no substantial change in the frequency of ternary relative to binary fission over this energy range; at 300 GeV it is about 0.4% for U, 1.1% for Bi, and 1.3% for Au. From observation of the forward to backward ratios of single (unpaired) tracks it was concluded that forward momentum transfer to heavy element targets peaks at ∼2 GeV and then decreases at higher beam energies.

NUCLEAR REACTIONS $U (p, f)$ , $Bi (p, f)$ , $Au (p, f)$ , $Ag (p, f)$ ; binary and ternary fission; $E = 0.6 - 300$ GeV; measured $σ (E)$ . Mica track detectors.

Final-state interactions in muon capture by deuterons

Q. Ho-Kim, J. P. Lavine, and H. S. Picker

Phys. Rev. C 13, 1966 (1976) - Published 1 May, 1976

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Prompted in part by the disparate theoretical estimates in the literature, we present a systematic study of the influence of the ${}^{1}S_{0} n - n$ final-state interaction on rates for the reaction $μ^{-} + d \to n + n + ν_{μ}$ , treated in impulse approximation with the standard Primakoff effective weak-interaction Hamiltonian. Instead of beginning with a particular $n - n$ potential, we use as our basic input a set of four-parameter Bargmann models of the ${}^{1}S_{0} n - n$ phase shift. By solving a "restricted inverse problem" we generate the necessary radial functions from these phase shifts. This procedure enables us to examine in a consistent way the sensitivity of the total capture rates and neutron energy spectrum to uncertainties in the phase shifts. We find that changes in the phase shifts at either high or low energies do not affect the rates noticeably. Hence, we conclude that this reaction is not a good tool for determining the $n - n$ scattering length. In addition, we investigate the effects of varying the off-shell behavior of the $n - n$ interaction by means of the method of short-range unitary transforms of Coester et al. We then find that the rates change dramatically. The doublet capture rate, for example, can be shifted from the 375 $\sec^{- 1}$ typical of the local potentials of the restricted inverse problem down to 236 $\sec^{- 1}$ . More accurate measurements of this rate could thus serve as constraints on the off-shell extrapolation of the $n - n$ interaction. Our results are in general agreement with those of Sotona and Truhlík.

NUCLEAR REACTIONS $μ^{-} + d \to n + n + ν_{μ}$ ; effect of ${}^{1}S_{0} n - n$ final-state interactions on rates, neutron spectra. Varied $n - n$ phase shifts and off-shell behavior.

Backward multiple scattering at high energy: Theory

T. W. Chen

Phys. Rev. C 13, 1974 (1976) - Published 1 May, 1976

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A backward multiple-scattering theory is formulated. We show first that backward multiple scattering at high energy is achieved mainly by single-backscattering processes. An approximate formula in terms of two-body scattering amplitudes is then obtained for the backward scattering amplitude. This formula is tested with numerical examples and shown to be accurate for high energy scattering at large angles.

NUCLEAR REACTIONS Multiple-scattering theory at medium to high energy at large angle; backward $π$ -nucleus scattering.

Pion-nucleus multiple scattering using separable $t$ matrices. I. Multiple scattering formalism

W. R. Gibbs, A. T. Hess, and W. B. Kaufmann

Phys. Rev. C 13, 1982 (1976) - Published 1 May, 1976

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The theory of pion-nucleus multiple scattering is developed in the fixed nucleon approximation, using a separable form for the pion-nucleon $t$ matrices. The solution of the set of equations represents multiple scattering to all orders. The extension of the theory to describe charge-exchange pion scattering is discussed.

NUCLEAR REACTIONS Pion-nucleus multiple-scattering theory, separable pion-nucleon $t$ matrices, fixed nucleon approximation.

Nuclear orientation of ${}^{76}{As}$

J. A. Barclay, S. S. Rosenblum, W. A. Steyert, and K. S. Krane

Phys. Rev. C 13, 1991 (1976) - Published 1 May, 1976

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$γ$ -ray angular distributions in the decay of oriented ${}^{76}{As}$ have been studied. The ${}^{76}{As}$ was oriented in iron at temperatures down to 4 mK. The first forbidden $β$ decays to the $2^{+}$ , $2^{+}$ , and $2^{+}$ states of ${}^{76}{Se}$ were deduced to be of predominantly $L = 0$ multipole character, in disagreement with previous work in the case of decays to the $2^{+}$ state. The $\frac{E 2}{M 1}$ multipole mixing ratios of the 657 and 1229 keV transitions were determined to be $δ (657) = + 5.2 \pm 0.2$ and $δ (1229) = - 0.49 \pm 0.05$ . The angular distribution of the 563-keV transition is more consistent with systematics if that transition is assigned as the $0^{+}$ - $2^{+}$ transition of ${}^{76}{Se}$ rather than as the $2^{+}$ - $0^{+}$ transition of ${}^{76}{Ge}$ . Spin assignments for the 2656- and 2670-keV levels are suggested to be 1 and 2, respectively.

RADIOACTIVITY ${}^{76}{As}$ [from ${}^{75}{As} (n, γ)$ ]. Measured $γ (θ)$ from polarized nuclei. ${}^{76}{As}$ -deduced $β$ decay multipolarities, ${}^{76}{Se}$ -deduced $\frac{E 2}{M 1}$ multipole mixing ratios $δ$ , levels $I^{π}$ .

Levels of ${}^{141}{Cs}$ and ${}^{141}{Ba}$ from the decays of ${}^{141}{Xe}$ and ${}^{141}{Cs}$

D. Otero, A. N. Proto, and F. C. Iglesias

Phys. Rev. C 13, 1996 (1976) - Published 1 May, 1976

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The $γ$ rays and conversion electrons following the $β$ decay of ${}^{141}{Xe}$ and ${}^{141}{Cs}$ have been measured by applying on-line mass-separation techniques to ${}^{235}U$ fission products. Internal-conversion coefficients were determined for 10 transitions, and level schemes for the two daughter nuclei, ${}^{141}{Cs}$ and ${}^{141}{Ba}$ , are proposed based on the study of $γ$ -singles, $γ γ$ -coincidence, and internal-conversion electron spectra.

RADIOACTIVITY ${}^{141}{Xe}$ , ${}^{141}{Cs}$ ; measured $E_{γ}$ , $I_{γ}$ , $γ γ$ coin, ICC; deduced $log ft$ ; measured $T_{\frac{1}{2}}$ ${}^{141}{Xe}$ , ${}^{141}{Cs}$ ; deduced levels. On-line measurements, mass-separated ${}^{235}U$ fission products.

Conversion electron studies on the new high-spin isomer in ${}^{154}{Eu}$

Y. Y. Chu and E. -M. Franz

Phys. Rev. C 13, 2011 (1976) - Published 1 May, 1976

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High-resolution conversion electron spectra between 6.05 and 122.68 keV have been measured using thin ${}^{154}{Eu}^{m}$ sources produced from the ( $p, n$ ) reaction on ${}^{154}{Sm}$ . In addition to the expected and observable conversion lines from ${}^{154}{Eu}^{m}$ , four other conversion lines were observed, and they could be attributed to the $L_{2}$ -, $L_{3}$ -, $M_{2}$ -, and $M_{3}$ -conversion lines of an $E 2$ , 32.61-keV transition. This energy matches the difference of the 100.80- and 68.14-keV transitions, and an $E 2$ assignment is appropriate for the transition connecting these two levels. No evidence of conversion lines of the isomeric transition was observed in this energy range and the upper limit of the isomeric transition energy is set at 13 keV. The multipolarities of all six transitions were determined from the electron measurements. The relative $γ$ -ray intensities were found to be significantly different from earlier results. A decay scheme is proposed which can account for nearly all the observations. The half-life of ${}^{154}{Eu}^{m}$ was determined to be 45.8 ± 0.3 min.

RADIOACTIVITY ${}^{154}{Eu}^{m}$ measured $T_{\frac{1}{2}}$ , $E_{γ}$ , $I_{γ}$ , $I_{ce}$ ; deduced $γ$ multipolarities, ${}^{154}{Eu}$ levels, $J$ , $π$ . Ge(Li) detectors, double-focusing $β$ -ray spectrometer.

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Singular cores in the three-body problem. III. Unique equations

Stripping channel contribution to the nonlocality of the deuteron optical potential

Photonuclear reactions in ${}^{90}{Zr}$

Photoneutron spectrum of lead following excitation by 8999, 8533, and 8120 keV photons

${}^{45}{Sc} (α, d) {}^{47}{Ti}$ reaction

Neutron resonance spectroscopy: ${}^{139}{La}$

Recoil-distance lifetime measurements of states in ${}^{47}V$ and ${}^{47}{Ti}$ induced by heavy-ion reactions

Elastic scattering of ${}^{84}{Kr}$ by ${}^{208}{Pb}$

Properties of high-spin states in ${}^{91}{Nb}$ and ${}^{91}{Zr}$ via ${}^{6}{Li}$ -induced reactions

High-spin states in ${}^{42}{Ca}$

Nuclear structure study of ${}^{141}{Nd}$ , ${}^{143}{Nd}$ , and ${}^{143}{Pm}$ by ${}^{13}C$ -induced reactions on ${}^{142}{Nd}$

Investigation of high-spin states in ${}^{38}{Ar}$

Angular distributions of specific gamma rays emitted in the deexcitation of prompt fission products of ${}^{252}{Cf}$

Interaction of 0.6-300 GeV protons with U, Bi, Au, and Ag; mica track detector study

Final-state interactions in muon capture by deuterons

Backward multiple scattering at high energy: Theory

Pion-nucleus multiple scattering using separable $t$ matrices. I. Multiple scattering formalism

Nuclear orientation of ${}^{76}{As}$

Levels of ${}^{141}{Cs}$ and ${}^{141}{Ba}$ from the decays of ${}^{141}{Xe}$ and ${}^{141}{Cs}$

Conversion electron studies on the new high-spin isomer in ${}^{154}{Eu}$

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