Recent Articles

Three-body photodisintegration of ${}^{3}{He}$

B. F. Gibson and D. R. Lehman

Phys. Rev. C 13, 477 (1976) - Published 1 February, 1976

Show Abstract

Cross sections for three-body photodisintegration of ${}^{3}{He}$ are calculated in the electric dipole approximation. The calculation is performed within the context of exact three-body theory with the two-nucleon interactions represented by $s$ -wave spin-dependent separable potentials fitted to low-energy nucleon-nucleon scattering data. The photodisintegration amplitude is expressed in terms of the fully off-shell nucleon-plus-correlated-pair amplitudes, a method applicable to any weak-process disintegration amplitude. The numerical results indicate: (1) The ${}^{3}{He} (γ, n) 2 p$ total cross section has a peak value of approximately 1 mb. (2) The neutron spectra for ${}^{3}{He} (γ, n) 2 p$ and the proton spectra for ${}^{3}{He} (γ, p) n p$ peak sharply in the region of the strong $p - p$ final-state interaction.

NUCLEAR REACTIONS Photodisintegration of ${}^{3}{He}$ ; exact three-body calculation; separable potentials; neutron and proton spectra.

Anomalous thresholds in an $\frac{N}{D}$ approach to nuclear reactions

J. M. Greben and L. P. Kok

Phys. Rev. C 13, 489 (1976) - Published 1 February, 1976

Show Abstract

The applicability of a recently developed coupled channel $\frac{N}{D}$ approach to nuclear reaction is extended to those cases where one of the channels contains a loosely bound particle giving rise to an anomalous threshold. The $\frac{N}{D}$ equations for the anomalous case are obtained by continuing the amplitudes in some external variable. We show that it is necessary to include part of the second order Born term in order to avoid certain singularities of the amplitudes in this external variable. The $\frac{N}{D}$ equations which are derived for the anomalous case are very similar to those in the normal case and quite amenable to numerical calculations. We also analyze the singularity structure of the second order Born terms in the energy plane. The occurrence of other types of singularities of the amplitudes in the external variable is investigated and their physical relevance is discussed.

NUCLEAR REACTIONS Dispersion relation method. Anomalous thresholds. Analytic structure of second order amplitudes. Generalized $\frac{N}{D}$ equations.

Partial decay widths of resonances in ${}^{29}P$

N. Tsoupas, H. J. Hausman, N. L. Gearhart, and G. H. Terry

Phys. Rev. C 13, 510 (1976) - Published 1 February, 1976

Show Abstract

Absolute differential cross sections of the ${}^{28}{Si} (p, p^{'}) {}^{28}{Si}^{*}$ (1.78 MeV) reaction have been measured for 12 scattering angles and at 88 different energies between bombarding energies of 3.0 to 5.2 MeV. In addition, 53 absolute cross sections of the ${}^{28}{Si} (p, p^{'} γ) {}^{28}{Si}$ angular correlations in the spin-flip geometry were also measured over the same energy region. From these and other data, the partial proton decay widths and phases of 14 resonances in ${}^{29}P$ were determined between excitation energies of 5.50 and 7.90 MeV.

NUCLEAR REACTIONS ${}^{28}{Si} (p, p_{1})$ , measured $σ (E, θ)$ , $E = 3.0 - 5.2$ MeV. ${}^{28}{Si} (p, p_{1} γ)$ , measured $p - γ$ correlations in the spin-flip geometry, determined partial proton decay widths, $Γ_{lj}$ , for 14 resonances. Calculated reduced widths.

${}^{14}N (p, α) {}^{11}C$ cross sections from 3.8 to 6.4 MeV

P. D. Ingalls, J. S. Schweitzer, B. D. Anderson, and Miguel Rios

Phys. Rev. C 13, 524 (1976) - Published 1 February, 1976

Show Abstract

Total cross sections for the ${}^{14}N (p, α) {}^{11}C$ reaction have been measured by using sealed gas targets and detecting annihilation radiation from the positron decay of ${}^{11}C$ . These measurements agree with the recent work of Jacobs et al. above 5.0 MeV and extend the measured cross sections to 3.8 MeV, where the cross section is a factor of 1000 smaller than the higher-energy cross sections. The results determine the low-energy normalization of the inverse ${}^{11}C (α, p) {}^{14}N$ reaction, reducing the ${}^{14}N$ production in big bang model calculations relative to results obtained by using estimated cross sections.

NUCLEAR REACTIONS ${}^{14}N (p, α)$ , $E = 3.8 - 6.4$ MeV, measured $σ (E)$ . Inferred $σ (E)$ and astrophysical cross section factor for inverse reaction. Sealed gas target.

${}^{19}F (d, α_{0}) {}^{17}O$ and ${}^{19}F (d, α_{1}) {}^{17}O$ reaction excitation function measurements between 2.34 and 14.45 MeV

R. E. Bigler, S. A. A. Zaidi, J. L. Horton, and H. Seitz

Phys. Rev. C 13, 528 (1976) - Published 1 February, 1976

Show Abstract

The ${}^{19}F (d, α_{0}) {}^{17}O$ and ${}^{19}F (d, α_{1}) {}^{17}O$ reactions have been studied by measuring excitation functions in 30 keV steps over the energy range between 2.34 and 14.45 MeV deuteron energies. Cross-section data were collected simultaneously at laboratory angles of 70°, 90°, 120°, 150°, and 170°. The measured excitation functions exhibit strong resonance structures superimposed upon a smoothly varying component. The widths of these resonances are on the order of 500 keV. The corresponding excitation energy of the compound nucleus ${}^{21}{Ne}$ ranged between 19 and 25 MeV. A narrow region encompassing one of the strongest resonances was measured in smaller steps to look for finer structure. No evidence for fine structure greater than 10 keV was observed.

NUCLEAR REACTIONS ${}^{19}F (d, α_{0, 1})$ , $E_{d} = 2.34 - 14.45$ MeV, measured excitation functions at five laboratory angles. Deduced direct reaction contribution of reaction mechanism.

The $E 0$ -pair decay of the $0^{+}$ second excited states in ${}^{42}{Ca}$ and ${}^{44}{Ca}$

M. Ulrickson, W. Hartwig, N. Benczer-Koller, Jack R. MacDonald, and J. W. Tape

Phys. Rev. C 13, 536 (1976) - Published 1 February, 1976

Show Abstract

The $E 0$ -pair decay branching ratio ( $\frac{Γ_{π}}{Γ}$ ) for the 1.84-MeV ( $0^{+}$ ) and 1.88-MeV ( $0^{+}$ ) second excited states of ${}^{42}{Ca}$ and ${}^{44}{Ca}$ were measured. The states were excited by proton inelastic scattering. $e^{-} - e^{+}$ pairs from the $E 0$ decay were stopped in a carbon cylinder and the resulting annihilation radiation was detected in two NaI(T1) detectors in triple coincidence with backscattered protons. The observed branching ratios are (0.88±0.14) × $10^{- 3}$ and (2.05±0.17) × $10^{- 2}$ for ${}^{44}{Ca}$ and ${}^{42}{Ca}$ , respectively, corresponding to monopole strengths of $ρ = 0.30 \pm 0.10$ and $ρ = 0.34 \pm 0.03$ . These results are consistent with a theoretical description of these states which includes large admixtures of deformed state wave functions.

NUCLEAR REACTIONS ${}^{42, 44}{Ca} (p, p^{'})$ , $E = 4.40$ MeV; ${}^{42, 44}{Ca}$ measured $E 0$ branching ratio. Deduced $E 0$ strength. Enriched targets.

${}^{48}{Ti} (p, {}^{3}{He}) {}^{46}{Sc}$ reaction

A. Guichard, W. Benenson, R. G. Markham, and H. Nann

Phys. Rev. C 13, 540 (1976) - Published 1 February, 1976

Show Abstract

The reaction ${}^{48}{Ti} (p, {}^{3}{He}) {}^{46}{Sc}$ has been studied at an incident energy of 40.2 MeV with an energy resolution of 17 keV. Sixty levels have been observed below 3.7 MeV. A distorted-wave Born approximation analysis permitted $L$ assignments for most of them. A comparison with the other information on ${}^{46}{Sc}$ is made.

NUCLEAR REACTION ${}^{48}{Ti} (p, {}^{3}{He})$ , $E_{p} = 40.2$ MeV; measured $σ (E_{{}^{3}{He}}, θ)$ ; enriched target. Deduced energies, $L$ values of ${}^{46}{Sc}$ levels.

Effect of inelastic coupling on $0^{+}$ analog transitions

V. A. Madsen, V. R. Brown, S. M. Grimes, C. H. Poppe, J. D. Anderson, J. C. Davis, and C. Wong

Phys. Rev. C 13, 548 (1976) - Published 1 February, 1976

Show Abstract

A comparison is made between experimental cross sections for the ( $p, n$ ) reaction to the ground-state analogs of the isotopes ${}^{92}{Mo}$ , ${}^{98}{Mo}$ , ${}^{100}{Mo}$ , and coupled-channel calculations including coupling to the $2^{+}$ and $3^{-}$ inelastic states and their analogs. When the coupling is included, very good fits are obtained for the ( $p, n$ ) $0^{+}$ analog differential cross section using uniform optical parameters for all three isotopes. Experimentally observed variations of about 50% in $\frac{σ}{(N - Z)}$ , which in distorted-wave Born approximation changes by only 10%, are explained by the coupling. A crude third-order distorted-wave Born approximation model is developed which shows that the three-step amplitudes $0^{+}$ → $2^{+}$ → $2^{+}$ analog → $0^{+}$ analog, $0^{+}$ → $2^{+}$ → $0^{+}$ → $0^{+}$ analog, and $0^{+}$ → $0^{+}$ analog → $2^{+}$ analog → $0^{+}$ analog are all in phase and are destructive to the dominant one-step $0^{+}$ → $0^{+}$ analog amplitude.

NUCLEAR REACTIONS ${}^{92}{Mo}$ , ${}^{98}{Mo}$ , ${}^{100}{Mo} (p, n)$ ; measured $2^{+}$ , $3^{-}$ analog cross sections at 18, 22, 26 MeV; $0^{+}$ , $2^{+}$ , and $3^{-}$ analog $σ (θ)$ at 16 and 26 MeV calculated including coupling to inelastic channels.

Features of the ( $t, p$ ) reaction below the Coulomb barrier of the entrance channel

Y. Iwasaki, T. Murata, T. Tamura, and Y. Nogami

Phys. Rev. C 13, 556 (1976) - Published 1 February, 1976

Show Abstract

The differential cross sections for the reactions ${}^{63, 65}{Cu} (t, p) {}^{65, 67}{Cu}$ were measured at $E_{t} = 3.2, 3.0, and 2.8$ MeV. For $L = 0$ ground-state transitions, the energy dependence of the values of the differential cross sections is strong and exponential, while the angular distribution shape, which is of a clear diffraction pattern in sharp contrast to the case of the sub-Coulomb ( $d, p$ ) reaction, does not change with small energy variation. The reactions proceed well below the Coulomb barrier of the entrance channel, yet through a direct process. A definite difference is observed between the angular distributions for the two ground-state transitions. The zero-range distorted-wave Born approximation can reproduce the energy dependence of the differential cross sections and the trend of isotope dependence of the angular distribution. In distorted-wave Born approximation calculations, a definite nuclear optical potential is needed for the triton-nucleus channel which is below the Coulomb barrier, in sharp contrast to the sub-Coulomb ( $d, p$ ) reaction. The triton-nucleus optical potential below the Coulomb barrier is nearly equal to the optical potential that works at energies of a few tens of MeV. The angular distribution for an $L = 2$ transition is forward-rising, though not diffractionlike, and can be reproduced on the whole by the zero-range distorted-wave Born approximation. It is confirmed for the first time that the ( $t, p$ ) reaction below the Coulomb barrier of the entrance channel takes place in an extended region outside the nucleus. It is argued and concluded on various grounds that the ( $t, p$ ) angular distribution shape below the Coulomb barrier of the entrance channel is sensitive to the radial two-neutron from factor outside the nucleus. Physical implications of the revealed features are discussed, especially on the coherence of the two-particle form factor and the proton and neutron distributions in the nuclear surface region.

NUCLEAR REACTIONS ${}^{63, 65}{Cu} (t, p)$ , $E = 2.8, 3.0, 3.2$ MeV; measured $σ (E; θ)$ ; DWBA analysis. Enriched ${}^{63}{Cu}$ , natural Cu targets, resolution 200 keV; $θ = 10 - 165 °$ . Revealed features below the Coulomb barrier, sensitivity to the form factor.

${}^{84}{Kr} (t, p) {}^{86}{Kr}$ and ${}^{86}{Kr} (t, p) {}^{88}{Kr}$ reactions

E. R. Flynn, J. D. Sherman, Nelson Stein, D. K. Olsen, and P. J. Riley

Phys. Rev. C 13, 568 (1976) - Published 1 February, 1976

Show Abstract

The ${}^{86}{Kr}$ and ${}^{88}{Kr}$ nuclei have been studied by the ${}^{84, 86}{Kr} (t, p)$ reactions at $E_{t} = 17.0$ MeV. Energy levels up to 6400 and 4400 keV excitation in ${}^{86}{Kr}$ and ${}^{88}{Kr}$ , respectively, were observed. Differential cross sections for many excited states have been extracted from 12° to 50° c.m. for ${}^{88}{Kr}$ and 12° to 55° c.m. for ${}^{86}{Kr}$ . The data are compared with DWBA calculations in order to obtain the angular momentum ( $L$ ) transfer as well as nuclear structure information. The excited $L = 0$ strength leading to ${}^{86}{Kr}$ in the region where the pairing vibration is expected is found to be fractionated and about $\frac{2}{3}$ of the intensity of the ${}^{86}{Kr}$ → ${}^{88}{Kr}$ (g.s.) transition strength. Strong $L = 2$ transitions are found above this excited $L = 0$ strength in ${}^{86}{Kr}$ and appear to have their parentage in the pairing quadrupole states represented by the first $2^{+}$ level in ${}^{88}{Kr}$ . The ${}^{86}{Kr}$ spectrum and transition strengths as found in the ( $t, p$ ) reaction are compared with the ${}^{86}{Kr} (p, p^{'})$ and ${}^{87}{Rb} (t, α)$ experiments.

NUCLEAR REACTIONS ${}^{86, 88}{Kr} (t, p)$ $E_{t} = 17.0$ MeV; measured $σ (θ)$ and level energies; deduced $J^{π}$ and enhancement factors from DWBA.

Failure of Bohr's compound nucleus hypothesis for the ${}^{98}{Mo} (n, γ) {}^{99}{Mo}$ reaction

R. E. Chrien, G. W. Cole, G. G. Slaughter, and J. A. Harvey

Phys. Rev. C 13, 578 (1976) - Published 1 February, 1976

Show Abstract

Some remarkable features in the radiative deexcitation of narrow resonant states formed by slow neutron capture in ${}^{98}{Mo}$ are pointed out. Earlier investigations indicating strong correlations between radiative widths and the single particle widths of both initial and final states involved in the reaction have been extended. A more precise set of resonance neutron widths has been developed from new total cross section measurements on isotopically separated molybdenum. From high resolution Ge(Li) detector measurements, a more complete set of $γ$ -ray transition intensities was derived. The resulting intensities are compared with intensities calculated from the valence neutron transition model of Lynn, with dipole matrix elements calculated from the ABACUS code of Auerbach. We conclude that the valence model works surprisingly well for ground state transitions from resonances with reduced widths of larger than about $10^{- 3}$ single particle units. For smaller resonances, correlations persist, but these must be accounted for by other mechanisms.

NUCLEAR REACTIONS Partial radiative widths, ${}^{98}{Mo} (n, γ)$ , neutron widths, spins, parities, valence model calculations, width correlations.

Levels of ${}^{53}{Mn}$ with the ${}^{52}{Cr} ({}^{3}{He}, d) {}^{53}{Mn}$ and ${}^{52}{Cr}$ ( ${}^{7}{Li}$ , ${}^{6}{He}$ ) ${}^{53}{Mn}$ reactions

G. D. Gunn, J. D. Fox, and G. J. KeKelis

Phys. Rev. C 13, 595 (1976) - Published 1 February, 1976

Show Abstract

The levels of ${}^{53}{Mn}$ populated by the reactions ${}^{52}{Cr} ({}^{3}{He}, d) {}^{53}{Mn}$ at 24 MeV and ${}^{52}{Cr}$ ( ${}^{7}{Li}$ , ${}^{6}{He}$ )- ${}^{53}{Mn}$ at 34 MeV were studied using The Florida State University quadrupole spectrometer. Angular distributions were taken from 5° to 60° for ${}^{52}{Cr} ({}^{3}{He}, d) {}^{53}{Mn}$ , and from 1° to 25° for the ${}^{52}{Cr}$ ( ${}^{7}{Li}$ , ${}^{6}{He}$ ) ${}^{53}{Mn}$ reaction. Angular distributions show the expected $L$ -dependent shapes which are well described by the distorted wave Born approximation. Relative spectroscopic factors are in excellent agreement with previous studies. The $J$ -dependent shape of the ( ${}^{7}{Li}$ , ${}^{6}{He}$ ) angular distributions at forward angles is used to identify the 2.68 and 3.48 MeV levels as $p_{\frac{1}{2}}$ , and the 4.07 and 4.43 MeV levels as $p_{\frac{3}{2}}$ . Absolute spectroscopic factors for the two reactions are in very good agreement and are about 30% lower than the values of previous studies. Seventeen levels of ${}^{53}{Mn}$ above 6 MeV are observed in one or both reactions. Angular distributions for eight levels are extracted for the ( ${}^{3}{He}, d$ ) reaction, including the three isobaric analog levels at 6.97, 7.54, and 8.03 MeV. Several of the levels above 6 MeV exhibit angular distributions which might be interpreted as being for either $l = 3$ or $l = 4$ transferred. These levels are identified as $g$ -wave final states on the basis of their strength and excitation energy. The spectroscopic factors for the unbound levels are derived by a technique of extrapolation of cross sections from the bound state analysis. The spectroscopic factors extracted for the isobaric analog levels are consistent with ( $d, p$ ) results to the parent states, within the limitations of the analysis.

NUCLEAR REACTIONS ${}^{52}{Cr} ({}^{3}{He}, d) {}^{53}{Mn}$ , $E = 24$ MeV; ${}^{52}{Cr}$ ( ${}^{7}{Li}$ , ${}^{6}{He}$ ) ${}^{53}{Mn}$ , $E = 34$ MeV; measured $σ (θ)$ ; DWBA analysis; ${}^{53}{Mn}$ levels; deduced $J^{π}$ and spectroscopic factors; enriched targets.

Gamma-ray spectroscopy studies of the lower excited states of ${}^{53}V$

J. G. Pronko, T. T. Bardin, and J. A. Becker

Phys. Rev. C 13, 608 (1976) - Published 1 February, 1976

Show Abstract

Previously unobserved $γ$ -ray decay modes of some excited states of ${}^{53}V$ were studied using the ${}^{51}V (t, p γ) {}^{53}V$ reaction at a bombarding energy of $E_{t} = 2.9$ MeV. Reaction proton- $γ$ -ray time coincident spectra were obtained using a variety of $γ$ -ray detectors: a 10-cm × 10-cm NaI(Tl) detector, a 4-mm × 3.81-cm NaI(Tl) detector, a 3.81-cm × 5.08-cm NE102 plastic scintillator, and a 20- ${cm}^{3}$ Ge(Li) detector. Lifetime information was deduced from both Doppler-shift attenuations obtained from the Ge(Li) $γ$ -ray spectra, and direct measurements using the plastic scintillator for the $γ$ -ray detector. Some of the measured excitation energies $E_{x}$ (keV) and lifetimes $τ_{m}$ are: (127.0 ± 1.4, ≤ 1 nsec); (227.8 ± 1.6, 5.85 ± 0.44 nsec); (1090.3 ± 2.0, $2 psec \leq τ_{m} \leq 1 nsec$ ); (1265.4 ± 1.2, $1.6 psec \leq τ_{m} \leq 1 nsec$ ); (1549.6 ± 3.0, ${0.11}_{- 0.07}^{+ 0.12}$ psec); (1652.5 ± 3.4, ≥ 0.65 psec); and (1856.2 ± 2.4, ≤ 0.04 psec). The experimental results were interpreted with respect to existing nuclear-model calculations and tentative spin assignments were made for a number of excited states.

NUCLEAR REACTIONS ${}^{51}V (t, p γ)$ , $E_{t} = 2.9$ MeV; measured $E_{γ}$ , $τ_{m}$ , and $Γ_{γ}$ for transitions in ${}^{53}V$ . Deduced tentative $J$ , $π$ assignments for ${}^{53}V$ excited states.

Lifetimes of ${}^{55}{Co}$ excited levels

G. F. Neal and P. R. Chagnon

Phys. Rev. C 13, 614 (1976) - Published 1 February, 1976

Show Abstract

Gamma-rays deexciting ${}^{55}{Co}$ levels have been studied in coincidence with deuterons detected in a particle telescope, in the ${}^{54}{Fe} ({}^{3}{He}, d γ) {}^{55}{Co}$ reaction. Excitation energies, relative $γ$ -ray intensities, and Doppler-shift attenuations of 12 levels have been measured. Mean lifetimes and transition strengths are reported. The Doppler-shifted line shape of the 2164→0-keV transition has been analyzed and has been found consistent with the assumption of a single level. Lifetimes of selected levels are: 2164 keV, $125_{- 20}^{+ 25}$ fs; 3301 keV, $50_{- 15}^{+ 20}$ fs; 3322 keV, $45_{- 10}^{+ 15}$ fs; 3641 keV, $300_{- 100}^{+ 150}$ fs; 4163 keV, $30_{- 10}^{+ 15}$ fs; 4714 keV, $300_{- 150}^{+ 200}$ fs; 4719 keV, < 30 fs; and 5172 keV, $10_{- 5}^{+ 10}$ fs.

NUCLEAR REACTIONS ${}^{54}{Fe} ({}^{3}{He}, d γ)$ , $E = 12.0 - 13.0$ MeV; measured $d γ$ coin, $E_{γ}$ , $I_{γ}$ , Doppler-shift attenuation. ${}^{55}{Co}$ deduced $τ$ .

Low-lying levels of ${}^{94}{Nb}$

E. C. Hagen, B. D. Kern, F. D. Snyder, and D. E. Miracle

Phys. Rev. C 13, 620 (1976) - Published 1 February, 1976

Show Abstract

The low-lying low-spin levels of ${}^{94}{Nb}$ have been investigated; these levels were populated via the ${}^{94}{Zr} (p, n γ) {}^{94}{Nb}$ reaction with a separated isotope ${}^{94}{Zr}$ foil target (96% ${}^{94}{Zr}$ ). Excitation functions of $γ$ rays were obtained at incident proton energies from 1.688 to 3.700 MeV. $γ - γ$ coincidences were observed at $E_{p} = 3.0$ MeV. The existence of additional levels at 301.5, 450.3, 666.2, and 785.0 keV has been established. Computed Hauser-Feshbach ( $p, n^{'}$ ) cross sections have been fitted to experimental cross sections deduced from the $γ$ -ray data with the resulting best-fit spin-parities: 140.4-keV level, $2^{-}$ ; 301.5, $2^{-}$ ; 334.2, $3^{+}$ ; 396.3, $4^{-}$ ; and 450.3, $3^{+}$ .

NUCLEAR REACTIONS ${}^{94}{Zr} (p, n γ)$ , $E = 1.688 - 3.700$ MeV; measured $E_{γ}$ , $I_{γ}$ , $γ - γ$ coincidence spectra. ${}^{94}{Nb}$ deduced levels, $J^{π}$ . Ge(Li) detectors. Enriched target.

Excitation of spin-1 states in ${}^{166, 168, 170}{Er}$ using bremsstrahlung

F. R. Metzger

Phys. Rev. C 13, 626 (1976) - Published 1 February, 1976

Show Abstract

Some 40 states in ${}^{166, 168, 170}{Er}$ , most of them previously unknown, have been excited using bremsstrahlung with ≤4.2 MeV endpoint energy. For all but three of these levels, the angular distribution of the resonantly scattered radiation favors the assignment of spin 1. For some of the strongly excited levels, linear polarization measurements have been performed. They indicate that these levels have positive parity. The branching ratios further characterize them as $K = 1$ excitations.

NUCLEAR REACTIONS ${}^{166, 168, 170}{Er} (γ, γ)$ , ( $γ, γ^{'}$ ); bremsstrahlung $E = 1.6 - 4.2$ MeV; measured $σ (98 °)$ and $σ (127 °)$ , $LP$ ; deduced $J$ , $π$ , $Γ$ . Enriched targets.

Mean lives and other properties of some levels in Ti

V. K. Rasmussen

Phys. Rev. C 13, 631 (1976) - Published 1 February, 1976

Show Abstract

Several levels in ${}^{46, 47, 48, 49, 50}{Ti}$ from 1.5 to 4.3 MeV are observed in the resonant scattering of bremsstrahlung by natural Ti. Six levels may be given immediate isotope assignments from verified branching to first excited states, seven may be assigned by close agreement of energies and other characteristics with levels observed in other reactions, one has a possible dual assignment, and one cannot be assigned. Widths and mean lives are given as well as information on spins, mixing ratios, and branching ratios.

NUCLEAR REACTIONS ${}^{46, 47, 48, 49, 50}{Ti} (γ, γ^{'})$ , ( $γ, γ^{'}$ ), $E_{x} = 1.3 - 4.7$ MeV; measured $σ (96 °)$ , $σ (126 °)$ ; deduced levels, $Γ_{0}$ , $Γ$ , mixing ratios, spins, parities.

Collective states in ${}^{233}U$ , ${}^{235}U$ , ${}^{237}{Np}$ , and ${}^{239}{Pu}$ excited by inelastic deuteron scattering

R. C. Thompson, J. R. Huizenga, and Th. W. Elze

Phys. Rev. C 13, 638 (1976) - Published 1 February, 1976

Show Abstract

Energy spectra of inelastically scattered 16-MeV deuterons were measured at angles of 90° and 125° using enriched targets of ${}^{233}U$ , ${}^{235}U$ , ${}^{237}{Np}$ , and ${}^{239}{Pu}$ . The octupole band resulting from the ground-state coupling to the $K^{π} = 0^{-}$ octupole vibration of the core is identified in ${}^{233}U$ , ${}^{237}{Np}$ , and ${}^{239}{Pu}$ and is tentatively assigned in ${}^{235}U$ . Evidence for the observation of ground-state coupling to the higher lying octupole bands is discussed for ${}^{233}U$ , ${}^{237}{Np}$ , and ${}^{239}{Pu}$ . Comparison is made of the core vibrations of the odd- $A$ nucleus with those observed in the adjacent even-even nuclei. The $K - 2$ and $K + 2 γ$ bands built on the ground state of ${}^{235}U$ are seen.

NUCLEAR REACTIONS ${}^{233}U$ , ${}^{235}U$ , ${}^{237}{Np}$ , ${}^{239}{Pu} (d, d^{'})$ , $E = 16$ MeV, measured $σ (E_{d^{'}}, θ = 90 °, 125 °)$ . ${}^{233}U$ , ${}^{235}U$ , ${}^{237}{Np}$ , ${}^{239}{Pu}$ deduced levels, $J$ , $K$ , $π$ . Enriched targets.

Elastic scattering of lithium by ${}^{9}{Be}$ , ${}^{10}B$ , ${}^{12}C$ , ${}^{13}C$ , ${}^{16}O$ , and ${}^{28}{Si}$ from 4 to 63 MeV

J. E. Poling, E. Norbeck, and R. R. Carlson

Phys. Rev. C 13, 648 (1976) - Published 1 February, 1976

Show Abstract

Elastic scattering angular distributions have been measured at energies between 4.0 and 13.0 MeV for ${}^{6}{Li}$ and ${}^{7}{Li}$ beams and targets of ${}^{10}B$ , ${}^{12}C$ , ${}^{13}C$ , ${}^{16}O$ , and ${}^{28}{Si}$ . Yield curves have been measured for energies from 3.0 to 13.0 MeV for ${}^{6}{Li}$ beams and targets of ${}^{9}{Be}$ , ${}^{12}C$ , ${}^{13}C$ , ${}^{16}O$ , and ${}^{28}{Si}$ , and for ${}^{7}{Li}$ and ${}^{12}C$ . The angular distributions, supplemented by published angular distributions, have been fitted with optical-model potentials. For ${}^{6}{Li}$ + ${}^{12}C$ , angular distributions were available at energies from 4.5 to 63.0 MeV. Potentials which gave fits to the data across the entire available energy range were obtained for each elastic scattering reaction. The usual ambiguities were observed in the optical-model potentials. In certain cases the back angles were not well fitted by parameter sets which were useful for all energies. The quality of the fits did not seem to be limited by experimental errors, which were generally better than 10% for our data; compound nucleus effects are presumed to be the cause of rapid energy variations in the angular distributions.

NUCLEAR REACTIONS ${}^{10}B$ , ${}^{12}C$ , ${}^{13}C$ , ${}^{16}O$ , ${}^{28}{Si}$ ( ${}^{6}{Li}$ , ${}^{6}{Li}$ ), ${}^{12}C$ , ${}^{13}C$ , ${}^{16}O$ ( ${}^{7}{Li}$ , ${}^{7}{Li}$ ), $E = 4 - 13$ MeV; measured $σ (θ)$ . Optical-model potentials for $E = 4 - 63$ . MeV.

${}^{30}{Si}$ + ${}^{14}N$ radiative capture

A. F. Zeller, H. S. Plendl, R. H. Davis, M. E. Williams, C. I. Delaune, and R. Holub

Phys. Rev. C 13, 661 (1976) - Published 1 February, 1976

Show Abstract

Cross sections for the reactions ${}^{30}{Si} ({}^{14}N, γ) {}^{44}{Sc}^{m}$ and ${}^{30}{Si} ({}^{14}N, n) {}^{43}{Sc}$ have been measured at five bombarding energies in the 40 to 62 MeV range. Residual activities produced by the reactions are unique and sufficiently long-lived so that the reaction yields in thick targets of natural Si were measured off-line with a Ge(Li) detector. By unfolding the range-energy function, the cross sections were extracted from the yields. The capture cross section increases from 7.5 to 22 μb over the bombarding energy range. The cross section for single neutron emission is 75 μb and constant within the errors of this experiment. A Blann-Plasil code calculation resulted in a value that is a factor of $10^{3}$ lower. The experimental results have been analyzed to determine an upper limit on the moment of inertia of the excited compound nucleus. Values of the upper limit depend on the choice of optical model parameters and the radius parameter in the moment of inertia.

NUCLEAR REACTIONS ${}^{30}{Si}$ + ${}^{14}N$ , $E = 40 - 62$ MeV; measured yields of activation products ${}^{43}{Sc}$ and ${}^{44}{Sc}^{m}$ ; calculated cross sections and limits on the moments of inertia. Natural targets, Ge(Li) detector.

Select page:

Physical Review C

Recent Articles

Filter

Recent Issues

Three-body photodisintegration of ${}^{3}{He}$

Anomalous thresholds in an $\frac{N}{D}$ approach to nuclear reactions

Partial decay widths of resonances in ${}^{29}P$

${}^{14}N (p, α) {}^{11}C$ cross sections from 3.8 to 6.4 MeV

${}^{19}F (d, α_{0}) {}^{17}O$ and ${}^{19}F (d, α_{1}) {}^{17}O$ reaction excitation function measurements between 2.34 and 14.45 MeV

The $E 0$ -pair decay of the $0^{+}$ second excited states in ${}^{42}{Ca}$ and ${}^{44}{Ca}$

${}^{48}{Ti} (p, {}^{3}{He}) {}^{46}{Sc}$ reaction

Effect of inelastic coupling on $0^{+}$ analog transitions

Features of the ( $t, p$ ) reaction below the Coulomb barrier of the entrance channel

${}^{84}{Kr} (t, p) {}^{86}{Kr}$ and ${}^{86}{Kr} (t, p) {}^{88}{Kr}$ reactions

Failure of Bohr's compound nucleus hypothesis for the ${}^{98}{Mo} (n, γ) {}^{99}{Mo}$ reaction

Levels of ${}^{53}{Mn}$ with the ${}^{52}{Cr} ({}^{3}{He}, d) {}^{53}{Mn}$ and ${}^{52}{Cr}$ ( ${}^{7}{Li}$ , ${}^{6}{He}$ ) ${}^{53}{Mn}$ reactions

Gamma-ray spectroscopy studies of the lower excited states of ${}^{53}V$

Lifetimes of ${}^{55}{Co}$ excited levels

Low-lying levels of ${}^{94}{Nb}$

Excitation of spin-1 states in ${}^{166, 168, 170}{Er}$ using bremsstrahlung

Mean lives and other properties of some levels in Ti

Collective states in ${}^{233}U$ , ${}^{235}U$ , ${}^{237}{Np}$ , and ${}^{239}{Pu}$ excited by inelastic deuteron scattering

Elastic scattering of lithium by ${}^{9}{Be}$ , ${}^{10}B$ , ${}^{12}C$ , ${}^{13}C$ , ${}^{16}O$ , and ${}^{28}{Si}$ from 4 to 63 MeV

${}^{30}{Si}$ + ${}^{14}N$ radiative capture

Filter

Recent Issues

Filter

Article Lookup

Enter a citation