Recent Articles

Analysis of exchange effects in the ${}^{16}O$ ( ${}^{6}{Li}$ , ${}^{4}{He}$ ) ${}^{18}F$ and ${}^{16}O$ ( ${}^{3}{He}$ , ${}^{1}H$ ) ${}^{18}F$ reactions

R. C. Goldfinger, W. Tobocman, and M. F. Werby

Phys. Rev. C 15, 686 (1977) - Published 1 February, 1977

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Exact finite-range cluster transfer distorted-wave Born approximation calculations were done for the reactions ${}^{16}O$ ( ${}^{6}{Li}$ , ${}^{4}{He}$ ) ${}^{18}F$ at 34 MeV and ${}^{16}O$ ( ${}^{3}{He}$ , ${}^{1}H$ ) ${}^{18}F$ at 19.8 MeV. Exchange contributions were included. The exchange process was found to be important for the ${}^{16}O$ ( ${}^{6}{Li}$ , ${}^{4}{He}$ ) ${}^{18}F$ reaction and it significantly improved the fit to the data. Spectroscopic factors for the exchange process in this reaction were extracted. Exchange is predicted to be inhibited by kinematic considerations for ${}^{16}O$ ( ${}^{3}{He}$ , ${}^{1}H$ ) ${}^{18}F$ ; the calculation confirmed that the exchange process was several orders of magnitude too small to affect the fit to the data.

NUCLEAR REACTIONS Exact finite-range DWBA calculations of differential cross sections for ${}^{16}O ({}^{6}{Li}, α) {}^{18}F$ at 34 MeV and ${}^{16}O ({}^{3}{He}, p) {}^{18}F$ at 19.8 MeV including exchange contributions.

Elastic scattering of ${}^{40}{Ca}$ by ${}^{40}{Ca}$

H. Doubre, J. C. Jacmart, E. Plagnol, N. Poffé, M. Riou, and J. C. Roynette

Phys. Rev. C 15, 693 (1977) - Published 1 February, 1977

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Angular distributions for the elastic scattering of ${}^{40}{Ca}$ by ${}^{40}{Ca}$ at $E_{c . m .} = 64.8, 71.8, 88, 93, 112.5, and 120$ MeV and excitation functions at 60°, 70°, and 90° (c.m.) over the c.m. energy range 55-120 MeV have been measured. Strong-absorption-model and optical-model analyses are presented. The predictions of several theoretical interaction potentials are compared with the data. The absence of structure in the excitation functions is studied and explained by the large mass and charge of the colliding nuclei.

NUCLEAR REACTIONS ${}^{40}{Ca}$ ( ${}^{40}{Ca}$ , ${}^{40}{Ca}$ ), $55 <~ E_{c . m .} <~ 120$ MeV; measured $σ (θ, E)$ ; parametrized $S$ -matrix and optical-model analyses; semiquantal interpretation of excitation functions.

Fragment-mass and kinetic-energy distributions from the spontaneous fission of ${}^{252}{No}$

C. E. Bemis, Jr., Robert L. Ferguson, Franz Plasil, R. J. Silva, Frances Pleasonton, and R. L. Hahn

Phys. Rev. C 15, 705 (1977) - Published 1 February, 1977

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Pre-neutron-emission fragment-mass and total-kinetic-energy distributions and the mass-energy correlations in the spontaneous-fission decay of 2.30-sec ${}^{252}{No}$ have been deduced from measured energies of coincident fragment pairs using silicon surface-barrier detectors. The ${}^{252}{No}$ for these measurements was produced in the ${}^{241}{Am} ({}^{15}N, 4 n)$ reaction and deposited on 40-μg ${cm}^{- 2}$ carbon foils using a He-jet technique. From an analysis of 154 correlated fission events, the average pre-neutron-emission total-kinetic energy, $〈 TKE 〉$ , was found to be 202.4±1.2 MeV. The mass distribution is decidedly asymmetric, similar to that observed for ${}^{252}{Cf}$ spontaneous fission, although a maximum in the $〈 TKE 〉$ curve as a function of fragment mass occurs for near-symmetric mass divisions as it does for the heavier isotopes of fermium. The measured spontaneous-fission-decay branching fraction for ${}^{252}{No}$ is 26.9±1.9% and the measured total half-life is 2.30±0.22 sec. The measured and deduced fission charàcteristics for ${}^{252}{No}$ are compared with those for the Cm, Cf, and Fm nuclides as well as with recent theoretical predictions.

RADIOACTIVITY, FISSION ${}^{252}{No} (α, sf)$ measured fragment-fragment coin $E$ , $T_{\frac{1}{2}}$ , $E α$ , $\frac{α}{sf}$ , $σ$ for ${}^{241}{Am} ({}^{15}N, 4 n)$ reaction; deduced pre-neutron fragment masses, energies, and total kinetic $E$ distribution. Enriched target.

Threshold pion production in heavy-ion collisions

G. F. Bertsch

Phys. Rev. C 15, 713 (1977) - Published 1 February, 1977

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Pion production from heavy-ion collisions is calculated in the independent-particle model, using nucleon-nucleon cross section data as input information. The assumption is made that only the first collision of a nucleon pair can create a pion, and also all collective effects are neglected. For the representative case of ${}^{16}O$ bombardment of ${}^{238}U$ at 250 MeV/nucleon, one out of seven inelastic collisions should produce a pion. One-third of these pions should be able to escape to the outside. The pion spectrum peaks at 20 MeV with an average energy of 50 MeV, viewed in the nucleon-nucleon center-of-mass frame.

NUCLEAR REACTIONS Pion production in heavy-ion collisions, calculate $σ$ , $σ (E_{π})$ .

( $p, pxn$ ) and ( $p, xn$ ) reactions and mechanisms on ${}^{133}{Cs}$ at 550 MeV

Martin A. Molecke and Albert A. Caretto, Jr.

Phys. Rev. C 15, 719 (1977) - Published 1 February, 1977

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The mechanism of the ( $p, pn$ ) reaction on ${}^{133}{Cs}$ with 550 MeV protons was deduced by measuring the recoil angular distribution between 0° and 180°, and the differential range distribution at 0° and 90°, for ${}^{132}{Cs}$ recoil nuclei. Similar measurements were made for the ( $p, p 4 n$ ) and ( $p, 3 n$ ) reaction products from ${}^{133}{Cs}$ . Cross sections were also measured for the production of ( $p, pxn$ ) and ( $p, xn$ ) products. The experimental data were compared to predictions derived from Monte Carlo cascade and evaporation calculations, as well as from simple kinematic models of possible reaction mechanisms. The results indicate that about 80% of the ( $p, pn$ ) reaction takes place by ( $p, p^{'}$ ) events followed by neutron evaporation.

NUCLEAR REACTIONS ${}^{133}{Cs} (p, p x n)$ , $x = 1, 2 - 4, 6, 8, and 10$ ; ${}^{133}{Cs} (p, x n)$ , $x = 1, 3, 5, 6, and 8$ ; natural Cs targets; $E (P) = 550$ MeV; measured: product $σ$ ; $σ (θ)$ and differential recoil ( $E$ ) for ${}^{132}{Cs}$ , ${}^{129}{Cs}$ , and ${}^{131}{Ba}$ nuclei.

$β$ decay and mass of the new neutron-rich isotope ${}^{53}{Ti}$

L. A. Parks, C. N. Davids, and R. C. Pardo

Phys. Rev. C 15, 730 (1977) - Published 1 February, 1977

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The new isotope ${}^{53}{Ti}$ has been produced with the ${}^{48}{Ca} ({}^{7}{Li}, p n) {}^{53}{Ti}$ reaction at $E_{{}^{7}{Li}} = 14 - 20$ MeV. The $β$ -decay scheme of ${}^{53}{Ti}$ was determined from $γ$ -ray singles and $γ - γ$ coincidence experiments using high-resolution Ge(Li) and intrinsic germanium detectors. The four strongest decay $γ$ rays have energies of 100.8, 127.6, 228.4 (all ± 0.1), and 1675.5 ± 0.3 keV, with relative intensities of 50.9 ± 2.7, 115.4 ± 12.0, 100, and 62.5 ± 6.7, respectively. The ${}^{53}{Ti}$ half-life was determined to be 32.7 ± 0.9 sec. Three new levels with excitation energies of 1958, 2550, and 2931 keV were observed in the daughter ${}^{53}V$ . The total ${}^{53}{Ti}$ decay energy of 5.02 ± 0.10 MeV was measured by performing a $β - γ$ coincidence experiment using a plastic scintillation detector for the $β$ rays. This yields a ${}^{53}{Ti}$ mass excess of -46.84 ± 0.10 MeV. The decay scheme provides $J^{π}$ restrictions for the observed states of ${}^{53}V$ , and these are compared with previous measurements and shell model calculations. The measured mass of ${}^{53}{Ti}$ is compared with various predictions.

RADIOACTIVITY ${}^{53}{Ti}$ [from ${}^{48}{Ca} ({}^{7}{Li}, p n)$ ]; measured $T_{\frac{1}{2}}$ , $E_{γ}$ , $I_{γ}$ , $E_{β}$ , $γ - γ$ coin, $β - γ$ coin; deduced decay scheme, $log ft$ , mass excess. ${}^{53}V$ deduced levels, $J$ restrictions, $π$ . Enriched targets, multiple rabbit facility; Ge(Li), intrinsic Ge, and plastic detectors.

Evidence for weak deformation in the 88-neutron nucleus ${}^{153}{Tb}$

M. D. Devous, Sr. and T. T. Sugihara

Phys. Rev. C 15, 740 (1977) - Published 1 February, 1977

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The decay of 6.3- $h^{153}$ Dy to levels in ${}^{153}{Tb}$ has been studied with high-resolution detectors. Sources were prepared by the ${}^{154}{Gd} ({}^{3}{He}, 4 n)$ reaction and chemically purified by ion exchange. A total of 329 $γ$ rays were assigned to ${}^{153}{Dy}$ decay; another 71 $γ$ rays may be associated with ${}^{153}{Dy}$ decay. The proposed decay scheme of 54 levels includes 319 of the 400 $γ$ rays. The $Q$ value for $β$ decay was measured to be 2250 ± 50 keV. Eleven low-lying positive-parity levels were interpreted in the Coriolis-mixed, particle-plus-rotor model as Nilsson states and rotational band members. Nilsson orbitals so interpreted include $\frac{5}{2^{+}} [402]$ , ground state; $\frac{3}{2^{+}} [411]$ , 147.4 keV; $\frac{5}{2^{+}} [413]$ , 218.6 keV; and $\frac{7}{2^{+}} [404]$ , 254.2 keV. The order and spacing of the negative-parity levels are consistent with rotation-alignment model predictions. For both positive- and negative-parity levels a deformation $β$ of about 0.15 is required to fit the data.

RADIOACTIVITY ${}^{153}{Dy}$ [from ${}^{154}{Gd} ({}^{3}{He}, 4 n)$ ]; measured $E_{γ}$ , $I_{γ}$ , $I_{ce}$ , $Q_{β}$ , $γ - γ$ , and $β^{+} - γ$ coin; deduced $α_{K}$ , $log ft$ . ${}^{153}{Tb}$ deduced levels, $J$ , $π$ . Enriched target, Ge(Li) and Si(Li) detectors.

Two-quasiparticle states in ${}^{250}{Cf}$ populated by electron capture decay of 8.6-h ${}^{250}{Es}$ isomer

M. S. Freedman, I. Ahmad, F. T. Porter, R. K. Sjoblom, R. F. Barnes, J. Lerner, and P. R. Fields

Phys. Rev. C 15, 760 (1977) - Published 1 February, 1977

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The electron capture decay scheme of the 8.6±0.1-h ${}^{250}{Es}$ isomer was investigated with high-resolution $γ$ -ray and $β$ -ray spectrometers and with two parameter coincidence analysis. Mass-separated samples of ${}^{250}{Es}$ produced by ${}^{249}{Bk} (α, 3 n)$ and ${}^{249}{Cf} (d, n)$ reactions were used for these measurements. We propose a decay scheme involving 32 transitions and 16 levels in ${}^{250}{Cf}$ . In addition to the ground state band, six rotational bands have been identified. The energies (keV) and $K π$ values of the bandheads are: 871.67 (2-), 1031.80 (2+), 1255.49 (4-), 1396.18 (5-), 1478.47 (5-), and 1499.62 (6-). The $log ft$ values of the electron capture transitions to the four highest bands were deduced and these were used to elucidate the principal two-quasiparticle components of these states. The $K π = 2 - and 2 +$ bands were interpreted as octupole and $γ$ -vibrational bands. The following two-quasiparticle configurations have been assigned: 1255.49 (4-), { $n [734] \frac{9}{2 -}; n [620] \frac{1}{2 +}$ }; 1396.18 (5-), { $p [633] \frac{7}{2 +}; p [521] \frac{3}{2 -}$ }; 1478.47 (5-), { $n [734] \frac{9}{2 -}; n [620] \frac{1}{2 +}$ }; and 1499.62 (6-), { $n [734] \frac{9}{2 -}; n [622] \frac{3}{2 +}$ }. The ground state of the 8.6-h ${}^{250}{Es}$ isomer has been given a spin-parity assignment of 6+ with the configuration { $n [734] \frac{9}{2 -}; p [521] \frac{3}{2 -}$ }. $KLL$ Auger energies and intensities for $Z = 98$ are reported. A $K$ fluorescence yield of 0.976±0.005 is obtained for Cf.

RADIOACTIVITY ${}^{250}{Es}$ [from ${}^{249}{Bk} (α, 3 n)$ and ${}^{249}{Cf} (d, n)$ ; measured $T_{\frac{1}{2}}$ , $E_{γ}$ , $I_{γ}$ , $E_{ce}$ , $I_{ce}$ , $γ γ$ -coin. ${}^{250}{Cf}$ deduced levels, $log ft$ (EC), $γ$ multipolarity, $I$ , $π$ , four two-quasiparticle states, two vibrational states. Mass-separated ${}^{250}{Es}$ . Toroidal $β$ spectrometer at 0.11% resolution (FWHM).

Spectrum shape of $K$ -orbital shakeoff electrons and accompanying nuclear beta particles. II. Decay of ${}^{147}{Pm}$

G. Schupp, M. S. Freedman, F. T. Porter, and D. A. Beery

Phys. Rev. C 15, 777 (1977) - Published 1 February, 1977

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The composite $K$ -orbital-shakeoff plus nuclear-electron spectrum was measured in coincidence with $K$ x rays in the $β$ emitter ${}^{147}{Pm}$ ( $E_{0} = 227$ keV) using the Argonne double-lens magnetic spectrometer and a Ge(Li) photon spectrometer. A bare NaI(Tl) scintillation electron detector allowed coincidence data to be recorded reliablydown to an electron energy of ∼5 keV. The measured spectrum showed prominently the expected intensity of Sm $L$ -Auger lines at 5-6 keV following $K$ x rays, and also the $K$ internal conversion line of the 121.2 keV transition in Sm populated by the weak (5.7 ± 0.7 × $10^{- 5}$ ; $log f t = 10.5$ ) inner $β$ group of ${}^{147}{Pm}$ . Neither of these features was seen in earlier measurements. Corrections for the small contribution of the inner $β$ group with its measured spectrum shape and intensity, and for the $L$ -Auger peak were made. The resulting spectrum shape and the total $K$ -ionization probability, $P_{K} = 8.7 \pm 0.7 \times 10^{- 5}$ , are both in good agreement with the $K$ shakeoff theory of Law and Campbell, including a 9% contribution to the spectrum from $K$ shakeup excitation. The spectrum shape agreement rejects a contribution to $K$ ejection by the direct collision mechanism exceeding 60% of that due to shakeoff, compared with Feinberg's theoretical estimate of 21% and to earlier experimental indications. This latter evidence firmly rejects a recent proposal by Isozumi et al. which suggests a direct collision contribution equal to shakeoff to make up for their twofold lower shakeoff prediction.

RADIOACTIVITY Measured electron spectrum in coin with $K$ x rays in decay of ${}^{147}{Pm}$ ; deduced shape and total $K$ -ionization probability.

Structure of ${}^{141}{Pm}$ from decay of $N = 79$ ${}^{141}{Sm}$

G. G. Kennedy, J. Deslauriers, S. C. Gujrathi, and S. K. Mark

Phys. Rev. C 15, 792 (1977) - Published 1 February, 1977

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The 10.2 min ${}^{141}{Sm}^{g}$ decay has been investigated. Positron, $γ$ -ray singles, $γ - γ$ , and $β^{+} - γ$ coincidence as well as conversion electron measurements led to a decay scheme comprising 27 transitions among 12 excited states with deduced $J^{π}$ assignments in ${}^{141}{Pm}$ . The $J^{π} = \frac{1}{2^{+}}$ for ${}^{141}{Sm}^{g}$ is confirmed. Internal conversion electrons resulting from the decay of 22.6 min ${}^{141}{Sm}^{m}$ have also been measured. The half-life of the $\frac{11}{2^{-}}$ state at 628.6 keV in ${}^{141}{Pm}$ populated in the latter decay has been measured to be 0.59 ± 0.02 μs. The $β^{+}$ end-point energy measurements yielded decay energy $Q_{EC} = 4.70 \pm 0.06 MeV and 4.56 \pm 0.04 MeV$ for ${}^{141}{Sm}^{m}$ and ${}^{141}{Sm}^{g}$ , respectively, and these values are compared with predictions of mass formulas. Systematics of the low-lying states and the $B (M 2)$ and $B (E 3)$ reduced transition rates in the odd- $A$ , $N = 80$ isotones are discussed.

RADIOACTIVITY ${}^{141}{Sm}^{m, g}$ from ${}^{144}{Sm} (p, p 3 n)$ and $(p, 4 n) {}^{141}{Eu} \to (β^{+}, EC)$ ; measured $T_{\frac{1}{2}}$ , $E_{γ}$ , $I_{γ}$ , $I_{ce}$ , $E_{β^{+}}$ , $γ - γ$ , $β^{+} - γ$ coin, $β^{+} - γ$ delay, deduced $Q_{EC}$ . ${}^{141}{Pm}$ deduced levels, $J$ , $π$ , $T_{\frac{1}{2}}$ , $log ft$ , ICC, $γ$ multipolarity. Enriched targets, Ge(Li), Si(Li), plastic detectors.

States in $N = 79$ ${}^{139}{Nd}$ populated in the decay of ${}^{139}{Pm}$

J. Deslauriers, S. C. Gujrathi, and S. K. Mark

Phys. Rev. C 15, 800 (1977) - Published 1 February, 1977

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The structure of ${}^{139}{Nd}$ is investigated through the $β^{+}$ decay of ${}^{139}{Pm}$ , whose decay half-life is measured to be 4.15 ± 0.05 min. A level scheme comprising 19 excited states and 47 transitions is constructed by means of $β^{+}$ , $γ$ -ray, and electron spectroscopy measurements. Using internal conversion electron measurements and the deduced $β$ -decay $ft$ values, $J^{π}$ assignments are made to states in ${}^{139}{Nd}$ and to the ground state of ${}^{139}{Pm}$ . From the $β$ end-point energy measurements, the total decay energy of ${}^{139}{Pm}$ has been established as 4.45 ± 0.08 MeV. The structure of ${}^{139}{Nd}$ is discussed in terms of the systematics of the odd- $A$ , $N = 79$ isotones. Decay energy systematics of the odd- $A$ , $N = 78 and 80$ isotones are also discussed.

RADIOACTIVITY ${}^{139}{Pm}$ from ${}^{142}{Nd} (p, 4 n)$ ; measured $T_{\frac{1}{2}}$ , $E_{γ}$ , $I_{γ}$ , $I_{ce}$ , $E_{β}^{+}$ , $γ - γ$ coincidence, deduced $Q_{EC}$ . ${}^{139}{Nd}$ deduced levels $J$ , $π$ , $log ft$ , ICC, $γ$ multipolarity. Enriched targets, Ge(Li), Si(Li), plastic, NaI(T1) detectors.

Ratio of electron capture to positron emission in the elementary-particle treatment of nuclear $β$ decay

W. B. McFarland and W. W. Repko

Phys. Rev. C 15, 809 (1977) - Published 1 February, 1977

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Nuclear size effects and Coulomb corrections are included in the expression for the electron capture rate $R_{ε}$ by using the "elementary-particle" approach of Armstrong and Kim. As an example, we use our result together with the corresponding expression for the positron emission rate $R_{β^{+}}$ to compute $\frac{R_{ε}}{R_{β^{+}}}$ for certain ${\frac{1}{2}}^{+} \to {\frac{1}{2}}^{+}$ and ${\frac{1}{2}}^{+} \to {\frac{3}{2}}^{+}$ transitions in Gd. Our ratios are in good agreement with conventional impulse-approximation calculations and for a wide range of nuclear parameters, do not exhibit the anomalies seen experimentally.

RADIOACTIVITY Finite size and Coulomb corrections to electron capture and $β$ -decay calculations.

Elastic scattering of deuterons by carbon

Girish K. Varma and Victor Franco

Phys. Rev. C 15, 813 (1977) - Published 1 February, 1977

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Deuteron-carbon elastic scattering is studied within the framework of the Glauber approximation. The full Glauber multiple scattering series is evaluated with simplified nuclear wave functions. An approximation in which deuteron-nucleus scattering is expressed in terms of nucleon-nucleus scattering amplitudes is shown to be accurate for small momentum transfers. The effects of the Coulomb field and the deuteron $D$ state are investigated. The impressive fit to the 650 MeV $d$ - ${}^{12}C$ elastic scattering data, obtained in a recent calculation, is shown to be due to additional approximations made in that analysis.

NUCLEAR REACTIONS ${}^{12}C (d, d)$ , $E = 650$ MeV; calculated $σ (E, θ)$ and $σ_{T} (E)$ , compared with measurements.

RAPID COMMUNICATION

Coulomb excitation effect in the reaction ${}^{144}{Nd}$ ( ${}^{12}C$ , ${}^{14}C$ ) ${}^{142}{Nd}$

Byung-taik Kim

Phys. Rev. C 15, 818(R) (1977) - Published 1 February, 1977

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RAPID COMMUNICATION

Odd-parity rotational band structure in ${}^{48}V$

L. E. Samuelson, W. H. Bentley, W. H. Kelly, R. A. Warner, F. M. Bernthal, and Wm. C. McHarris

Phys. Rev. C 15, 821(R) (1977) - Published 1 February, 1977

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A second odd-parity rotational band in the $f_{\frac{7}{2}}$ -shell nucleus ${}_{23}^{48}V_{25}$ , based on a 1099.1 keV state with $K^{π} = 4^{-}$ , has been identified up to the $8^{-}$ member. Also, corrections are given for the previously reported $1^{-}$ band. These bands can be interpreted as the singlet and triplet couplings of the $Ω^{π} [N n_{Z} Λ Σ] = \frac{3}{2^{+}} [202_{↓}]$ proton and $\frac{5}{2^{-}} [312_{↑}]$ neutron Nilsson orbitals, indicating prolate deformation.

NUCLEAR REACTIONS ${}^{46}{Ti} (α, p n)$ , ${}^{48}{Ti} (p, n)$ ; measured $γ - γ$ coin, ce, ${}^{48}V$ deduced levels, $J$ , $π$ , $Λ$ , ICC. Splitting of Nilsson levels.

RAPID COMMUNICATION

Remarks on magnetic moments

Larry Zamick

Phys. Rev. C 15, 824(R) (1977) - Published 1 February, 1977

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It is noted that the deviations of the isoscalar magnetic moments from Schmidt values behave in a systematic way, being positive for the jackknife cases and negative for the stretch cases. Other subjects of interest concerning magnetic moments are discussed.

NUCLEAR STRUCTURE Systematics of isoscalar magnetic moments.

RAPID COMMUNICATION

Search for the collective $M 1$ resonance in ${}^{208}{Pb}$

R. J. Holt, R. M. Laszewski, and H. E. Jackson

Phys. Rev. C 15, 827(R) (1977) - Published 1 February, 1977

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The photoneutron polarization from resonances near the threshold region was observed for the ${}^{208}{Pb} (γ, {\vec{n}}_{0}) {}^{207}{Pb}$ reaction. Resonances located at photoneutron energies of 180 and 315 keV, previously believed to be a large part of the giant $M 1$ resonance, are shown to be $E 1$ excitations.

NUCLEAR REACTIONS ${}^{208}{Pb} (γ, \vec{n}) {}^{207}{Pb}$ , measured $p (θ, E_{n})$ ; $θ = 90 °, 135 °$ ; $E_{n} = 180 - 320$ keV.

RAPID COMMUNICATION

Multipole mixing ratios from polarized-beam gamma-ray singles measurements

H. T. King, M. Hass, R. Kaita, and A. B. Robbins

Phys. Rev. C 15, 829(R) (1977) - Published 1 February, 1977

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A simple and fast method for determining $γ$ -ray multipole mixing ratios is described which is based on a comparison of the left-right asymmetries of two different $γ$ transitions from a state excited in a polarized-beam reaction. The method requires no particle- $γ$ or $γ - γ$ coincidence measurement. It is illustrated here by means of a determination of the $\frac{E 2}{M 1}$ mixing ratios for ${}^{24}{Mg}$ ( $2_{2}^{+}$ → $2_{1}^{+}$ ) and ${}^{26}{Mg}$ ( $2_{2}^{+}$ → $2_{1}^{+}$ ).

NUCLEAR REACTIONS ${}^{24, 26}{Mg}$ ( $\vec{p}, p^{'} γ$ ), $E = 6.6, 7.5$ MeV; measured singles $γ$ -ray asymmetry; ${}^{24}{Mg}$ , ${}^{26}{Mg}$ deduced $2_{2}^{+}$ → $2_{1}^{+}$ $\frac{E 2}{M 1}$ mixing ratios.

RAPID COMMUNICATION

Quadrupole moment of the first $2^{+}$ state of ${}^{18}O$

K. Klingenbeck

Phys. Rev. C 15, 831(R) (1977) - Published 1 February, 1977

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Using SU(3) techniques, a minimal value of the quadrupole moment of the first $2^{+}$ state of ${}^{18}O$ is derived for a two-particle model space and a constant effective charge $e_{n}$ . The influences of state dependent effective charges are discussed. A comparison with experimental measurements yields evidence for the failure of the two-particle model.

NUCLEAR STRUCTURE ${}^{18}O$ , theoretical limits for $q$ of the first $2^{+}$ state, using SU(3) techniques. Influence of state dependent effective charges.

RAPID COMMUNICATION

Resonance at $E_{c . m .} = 12.8$ MeV in the ${}^{12}C$ + ${}^{16}O$ system

P. Taras, G. Rao, N. Schulz, J. P. Vivien, B. Haas, J. C. Merdinger, and S. Landsberger

Phys. Rev. C 15, 834(R) (1977) - Published 1 February, 1977

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An intermediate-type resonance of width $Γ_{c . m .} = 130 \pm 25$ keV has been observed in the excitation functions of the $n$ , $p$ , $d$ , and $α$ -particle exit channels at $E_{c . m .} = 12.77$ MeV in the ${}^{12}C$ + ${}^{16}O$ reaction. The energy of the resonance as well as its probable spin $J = 8 ℏ$ are in good agreement with the predictions obtained from the semiclassical expression for the grazing orbit.

NUCLEAR REACTIONS ${}^{12}C ({}^{16}O, n)$ , $E_{c . m .} = 10.7 - 15.9$ MeV; measured $σ (n)$ ; ${}^{12}C ({}^{16}O, p)$ , ${}^{12}C ({}^{16}O, d)$ , ${}^{12}C ({}^{16}O, α)$ , ${}^{12}C$ ( ${}^{16}O$ , ${}^{16}O$ ), $E_{c . m .} = 12.43 - 13.93$ MeV; measured $σ (p)$ , $σ (d)$ , $σ (α)$ , $σ ({}^{16}O)$ .

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Analysis of exchange effects in the ${}^{16}O$ ( ${}^{6}{Li}$ , ${}^{4}{He}$ ) ${}^{18}F$ and ${}^{16}O$ ( ${}^{3}{He}$ , ${}^{1}H$ ) ${}^{18}F$ reactions

Elastic scattering of ${}^{40}{Ca}$ by ${}^{40}{Ca}$

Fragment-mass and kinetic-energy distributions from the spontaneous fission of ${}^{252}{No}$

Threshold pion production in heavy-ion collisions

( $p, pxn$ ) and ( $p, xn$ ) reactions and mechanisms on ${}^{133}{Cs}$ at 550 MeV

$β$ decay and mass of the new neutron-rich isotope ${}^{53}{Ti}$

Evidence for weak deformation in the 88-neutron nucleus ${}^{153}{Tb}$

Two-quasiparticle states in ${}^{250}{Cf}$ populated by electron capture decay of 8.6-h ${}^{250}{Es}$ isomer

Spectrum shape of $K$ -orbital shakeoff electrons and accompanying nuclear beta particles. II. Decay of ${}^{147}{Pm}$

Structure of ${}^{141}{Pm}$ from decay of $N = 79$ ${}^{141}{Sm}$

States in $N = 79$ ${}^{139}{Nd}$ populated in the decay of ${}^{139}{Pm}$

Ratio of electron capture to positron emission in the elementary-particle treatment of nuclear $β$ decay

Elastic scattering of deuterons by carbon

Coulomb excitation effect in the reaction ${}^{144}{Nd}$ ( ${}^{12}C$ , ${}^{14}C$ ) ${}^{142}{Nd}$

Odd-parity rotational band structure in ${}^{48}V$

Remarks on magnetic moments

Search for the collective $M 1$ resonance in ${}^{208}{Pb}$

Multipole mixing ratios from polarized-beam gamma-ray singles measurements

Quadrupole moment of the first $2^{+}$ state of ${}^{18}O$

Resonance at $E_{c . m .} = 12.8$ MeV in the ${}^{12}C$ + ${}^{16}O$ system

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