Recent Articles

Long-lived states at high excitation energies in ${}^{8}{Be}$ and ${}^{10}B$

F. Ajzenberg-Selove, C. F. Maguire, D. L. Hendrie, D. K. Scott, and J. Mahoney

Phys. Rev. C 13, 46 (1976) - Published 1 January, 1976

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A study of highly excited states in ${}^{8}{Be}$ and ${}^{10}B$ has been conducted using the ${}^{9}{Be} ({}^{3}{He}, α)$ and ${}^{11}B ({}^{3}{He}, α)$ reactions at $E ({}^{3}{He}) = 49.3$ MeV and the Berkeley magnetic spectrometer. We observe three new states in ${}^{8}{Be}$ at $E_{x} = 22.05, 22.63, and 22.98$ MeV (±0.1 MeV) with $Γ_{c . m .} < 0.3$ MeV. In ${}^{10}B$ we confirm the previously known states ${}^{10}B^{*}$ (10.85, 11.52, 12.56) and report a new state ${}^{10}B^{*}$ (13.49) with $Γ_{c . m .} = 0.3$ MeV, in addition to two broader states. Comparisons are made with the analog regions in ${}^{8}{Li}$ and ${}^{10}{Be}$ .

NUCLEAR REACTIONS ${}^{9}{Be} ({}^{3}{He}, α)$ , ${}^{11}B ({}^{3}{He}, α)$ , $E = 49.3$ MeV; measured $σ (θ)$ . $Γ$ , ${}^{8}{Be}$ , ${}^{10}B$ , deduced levels.

Mass of ${}^{8}C$

R. E. Tribble, R. A. Kenefick, and R. L. Spross

Phys. Rev. C 13, 50 (1976) - Published 1 January, 1976

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A new determination of the mass excess of ${}^{8}C$ by the ${}^{12}C$ ( ${}^{4}{He}$ , ${}^{8}{He}$ ) ${}^{8}C$ reaction has yielded a value of 35.10 ± 0.03 MeV. The new value is in good agreement with the quadratic isobaric multiplet mass equation prediction. Higher order cubic and quartic mass equation coefficients are found to be small for the $A = 8$ isobaric quintet.

NUCLEAR REACTIONS ${}^{12}C$ ( ${}^{4}{He}$ , ${}^{8}{He}$ ). Measured ${}^{8}C$ mass. Deduced coefficients of the isobaric multiplet mass equation for the $A = 8$ quintet.

Investigation of the ${(d_{\frac{5}{2}})}^{2}$ and ( $d_{\frac{5}{2}} s_{\frac{1}{2}}$ ) two-particle configurations in ${}^{18}O$ using the ${}^{17}O (d, p) {}^{18}O$ reaction at 18 MeV

T. K. Li, D. Dehnhard, Ronald E. Brown, and P. J. Ellis

Phys. Rev. C 13, 55 (1976) - Published 1 January, 1976

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Differential cross sections of deuteron elastic scattering from ${}^{17}O$ and of the ${}^{17}O (d, p) {}^{18}O$ reaction have been measured at a deuteron bombarding energy of 18 MeV for transitions to 12 states in ${}^{18}O$ up to an excitation energy of 6.341 MeV. Absolute spectroscopic factors were extracted with the aid of distorted-wave-Born-approximation calculations. The results are compared with theoretical calculations and show a distinct preference for a weak-coupling model. Diagonal matrix elements of the effective neutron-neutron interaction were deduced from the data for the ${(d_{\frac{5}{2}})}^{2}_{0^{+}, 2^{+}, 4^{+}}$ and ${(d_{\frac{5}{2}} s_{\frac{1}{2}})}_{2^{+}, 3^{+}}$ configurations. A theoretical estimate of the errors involved is in qualitative agreement with the deviations observed between experiment and theory.

NUCLEAR REACTIONS ${}^{17}O (d, d)$ , ( $d, p$ ), $E = 18.0$ MeV; measured $σ (θ)$ , deduced optical-model parameters; measured $σ (E_{p}, θ)$ ${}^{18}O$ levels deduced $l$ , $S$ , effective interactions. Enriched target.

( $p, 2 p$ ) and ( $p, p d$ ) reactions on ${}^{3}H$ at 45.6 MeV

D. I. Bonbright, S. A. Elbakr, A. Houdayer, C. A. Miller, D. J. Roberts, E. S. Y. Tin, W. T. H. van Oers, and J. W. Watson

Phys. Rev. C 13, 68 (1976) - Published 1 January, 1976

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The reactions ${}^{3}H (p, 2 p) n n$ , ${}^{3}H (p, p d) n$ , and ${}^{3}{He} (p, 2 p) d$ , ${}^{3}{He} (p, 2 p) pn$ , and ${}^{3}{He} (p, p d) p$ have been studied at 45.6 and 45.0 MeV, respectively, using coplanar symmetric and asymmetric geometries. An angular correlation has been obtained for the ${}^{3}{He} (p, 2 p) [n n]$ reaction, where [ $n n$ ] denotes an $n - n$ pair with low energy for its relative motion. Energy sharing data for this reaction have also been obtained at a number of coplanar asymmetric angle pairs which allow zero spectator momentum. Within the framework of the plane wave impulse approximation the extracted momentum distributions of the $p + [n n]$ system in ${}^{3}H$ and the $p + d$ and $p + d^{*}$ systems in ${}^{3}{He}$ are compared with predictions calculated using relatively simple wave functions for ${}^{3}H$ , ${}^{3}{He}$ , $d$ , $d^{*}$ , and [ $n n$ ]. Reasonable agreement between the shapes of the extracted and theoretical momentum distributions has been obtained, but there exist differences between the momentum distributions extracted from the angular correlation and energy sharing data. The ${}^{3}H (p, p d)$ quasifree scattering enhancements exhibit shifts in the peak position away from the minimum in the momentum of the spectator neutron. Comparison of the four-body continua of the ${}^{3}H (p, 2 p) n n$ reactions reveals enhancements which can be interpreted as due to pseudo-two-body processes, namely, the $p - d^{*}$ quasifree scattering process and the reaction $p + {}^{3}H \to d^{*} + d^{*}$ .

NUCLEAR REACTIONS ${}^{3}H (p, 2 p)$ , ${}^{3}H (p, p d)$ , $T_{1} = 45.6$ MeV; ${}^{3}{He} (p, 2 p)$ , ${}^{3}{He} (p, 2 p)$ , $T_{1} = 45.0$ MeV; measured $\frac{d σ}{(d T_{3} d Ω_{3} d Ω_{4})}$ in coplanar geometry; deduced momentum distributions using PWIA; compared with theoretical momentum distributions; investigated four-body continua.

Single proton transfer to ${}^{29, 30}P$ states

W. W. Dykoski and D. Dehnhard

Phys. Rev. C 13, 80 (1976) - Published 1 January, 1976

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Differential cross sections were measured for the ( ${}^{3}{He}, d$ ) reaction on ${}^{28}{Si}$ and ${}^{29}{Si}$ at $E_{{}^{3}{He}} = 25$ MeV by use of an Enge split-pole spectrometer. Up to 19 point angular distributions for transitions to 12 states in ${}^{29}P$ below 6.4 MeV excitation energy and to 66 states in ${}^{30}P$ below 8.7 MeV were analyzed in the distorted-wave Born approximation. The optical model parameters required for the distorted-wave Born approximation analysis were obtained from elastic ${}^{3}{He}$ scattering data which were taken on ${}^{28}{Si}$ , ${}^{29}{Si}$ , and ${}^{30}{Si}$ . A number of ${}^{30}P$ levels were found to have large components of simple two-particle structure, with one particle in the $2 s_{\frac{1}{2}}$ shell and the other either in the $2 s_{\frac{1}{2}}$ , $1 d_{\frac{3}{2}}$ , $1 f_{\frac{7}{2}}$ , or $2 p_{\frac{3}{2}}$ shells. Specifically, the states at 6092 and 7048 keV were assigned $J^{π} = 3^{-}$ , $T = 1$ and $J^{π} = 4^{-}$ , $T = 1$ , respectively, because they were found to carry a significant fraction of the ( $2 s_{\frac{1}{2}}$ ) ( $1 f_{\frac{7}{2}}$ ) strength. However, the $T = 0$ components of the ${(2 s_{\frac{1}{2}})}^{2}_{1^{+}}$ , ( $2 s_{\frac{1}{2}}$ ) ${(1 d_{\frac{3}{2}})}_{1^{+}}$ , and ${(1 d_{\frac{5}{2}})}^{- 1} {(2 s_{\frac{1}{2}})}^{3}_{3^{+}}$ configurations were found to be distributed among a large number of states. Spin assignments were made based on shapes of the angular distributions and analog relations to ${}^{30}{Si}$ states. An estmate of the extent to which the $1 d_{\frac{5}{2}}$ proton shell is filled in ${}^{28}{Si}$ and ${}^{29}{Si}$ was extracted.

NUCLEAR REACTIONS ${}^{28, 29}{Si} ({}^{3}{He}, d)$ , ${}^{28, 29, 30}{Si}$ ( ${}^{3}{He}$ , ${}^{3}{He}$ ), $E = 25$ MeV; measured $σ (E_{d}, θ)$ , ${}^{29, 30}P$ deduced levels, $l$ , $J$ , $π$ , $T$ , spectroscopic factors; measured $σ (θ)$ , deduced optical model parameters, enriched target.

Isospin mixing in nuclear resonance levels

Chindhu S. Warke

Phys. Rev. C 13, 9 (1976) - Published 1 January, 1976

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The problem of isospin mixing in nuclear resonance levels is studied using the framework of Feshbach's unified theory of reactions. The nuclear matrix elements occurring in the theory are expressed in terms of the measured quantities. These relations would be useful in interpreting the experimental data. The unitarity limit on the phase of the mixing amplitude is derived.

NUCLEAR REACTIONS Feshbach's theory, complex isospin mixing coefficient; obtained unitarity bound.

( ${}^{3}{He}, 2 p$ ) reaction on ${}^{208}{Pb}$

A. Gavron

Phys. Rev. C 13, 98 (1976) - Published 1 January, 1976

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The angular distribution and relative energy of the proton pair emitted in the ${}^{208}{Pb}$ -( ${}^{3}{He}, 2 p$ ) reaction was measured by a simple technique involving a single semiconductor telescope. The experimental results indicate that the final state interaction between the two protons is small when compared to the interaction between the target nucleus and each one of the protons.

NUCLEAR REACTIONS ${}^{208}{Pb} ({}^{3}{He}, 2 p)$ $E = 21 - 25$ MeV, measured angular distribution, relative $p - p$ energy, deduced $p - p$ correlation.

Investigation of giant resonances as doorway states in inelastic nucleon scattering from ${}^{12}C$

H. V. Geramb, K. Amos, R. Sprickmann, K. T. Knöpfle, M. Rogge, D. Ingham, and C. Mayer-Böricke

Phys. Rev. C 12, 1697 (1975) - Published 1 December, 1975

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A formalism for inelastic nucleon scattering from nuclei is developed which takes into account explicitly the effect of giant multipole resonance states. The transition amplitudes derived from this formalism, when energy averaged, separate into two primary components. The first is the slowly energy varying direct reaction amplitude that is mediated by an effective interaction while the second is the energy varying semidirect reaction amplitude associated with doorway state excitations of giant resonances. The determination of quantum numbers and associated properties of giant resonances follow from analyses of inelastic nucleon scattering to low lying nuclear states. Specifically, from the application to the inelastic scattering of 23 to 45 MeV protons from ${}^{12}C$ leading to the $1^{+}$ (12.71 MeV $T = 0 and 15.1$ MeV $T = 1$ ) states, the strength distributions of the giant isovector $E 1$ and isoscalar $E 2$ and $E 3$ resonances are determined.

NUCLEAR REACTION ${}^{12}C (p, p^{'})$ , $E = 22.5 - 45$ MeV; measured $σ (θ)$ ; DWBA analysis; included resonance effects; deduced ${}^{12}C$ giant dipole, giant quadrupole strength distribution.

Study of the ${}^{21}{Ne} (t, p) {}^{23}{Ne}$ reaction

P. Desgrolard, B. Chambon, D. Drain, C. Pastor, and A. Dauchy

Phys. Rev. C 12, 1711 (1975) - Published 1 December, 1975

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Investigation of the ${}^{21}{Ne} (t, p) {}^{23}{Ne}$ reaction with 3 and 3.25 MeV projectiles reveals eight new (energy) levels between $E_{x} = 5.3 and 6.5$ MeV. Absolute differential cross sections for 18 proton groups are reported. Distorted-wave Born approximation analysis and Hauser-Feshbach calculations indicate that $L = 0$ is involved in the formation of one of the members of the doublets at $E_{x} = 3.432 - 3.458 and 4.995 - 5.036$ MeV as well as in the formation of a new level at 5.74 ± 0.04 MeV. A mixture of $L = 0$ and $L = 2$ transfer is associated with the formation of the 1.822 MeV level. For these four levels $J^{π} = {\frac{3}{2}}^{+}$ is deduced.

NUCLEAR REACTIONS ${}^{21}{Ne} (t, p)$ , $E = 3.25$ MeV, measured $σ (θ)$ ; ${}^{23}{Ne}$ levels deduced $E_{x}$ , $L$ , $π$ , $J$ . Enriched target.

Polarization in neutron-proton scattering at 29.6 MeV

R. A. Eldred, B. E. Bonner, and T. A. Cahill

Phys. Rev. C 12, 1717 (1975) - Published 1 December, 1975

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The polarization in neutron-proton scattering at 29.6 MeV was deduced from asymmetries measured at every 10° c.m. from 50 to 150° c.m. The incident neutron beam was derived from a high-pressure deuterium gas cell via the ${}^{2}H (d, n) {}^{3}{He}$ reaction at 37° c.m. The beam passed through a spin rotation magnet and, at the target location 5.4 m from the gas cell, possessed a flux of 5 × $10^{5}$ n/sec and a polarization of 0.32 ± 0.04. Data between 50 and 110° c.m. were obtained using scintillating CH target in coincidence with neutron detectors, while data between 120 and 150° c.m. were obtained using recoil protons from a C $H_{2}$ target. Total errors in the derived polarizations ranged from ± 0.007 to ± 0.022. These data agree very well with three previous values measured near 30 MeV at Los Alamos, but they disagree with Harwell data indicating small or negative polarizations near 150° c.m. The present results agree well with predictions of the Livermore X and Yale IV phase shift sets, but slightly favor the former.

NUCLEAR REACTIONS ${}^{1}H (n, n)$ , $E = 29.6$ MeV; $P (θ)$ , $θ_{c} = 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, and 150 °$ ; deduced Legendre coefficients.

How important are two-step processes in ${}^{16}O ({}^{3}{He}, d) {}^{17}F$ ?

H. T. Fortune, L. R. Medsker, J. D. Garrett, and H. G. Bingham

Phys. Rev. C 12, 1723 (1975) - Published 1 December, 1975

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Angular distributions were measured for the ${}^{16}O ({}^{3}{He}, d) {}^{17}F$ reaction leading to the first four states of ${}^{17}F$ . Comparison with distorted-wave Born-approximation (DWBA) calculations yields spectroscopic factors of 0.94 and 0.83 for the ground and first-excited states, respectively. Comparison with unbound DWBA predictions calculated from the known proton widths of the next two states indicates the presence of a large two-step component for population of the $½^{-}$ state and possibly of the ${\frac{5}{2}}^{-}$ state.

NUCLEAR REACTIONS ${}^{16}O ({}^{3}{He}, d)$ , $E = 18.0$ MeV, measured $σ (E_{d}, θ)$ . DWBA analysis.

Neutron resonances in ${}^{24}{Na}$ via the ( $d, p$ ) reaction

G. Blanpied, R. Liljestrand, J. Lynch, J. McIntyre, L. Ray, and G. W. Hoffmann

Phys. Rev. C 12, 1726 (1975) - Published 1 December, 1975

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Neutron resonances in ${}^{24}{Na}$ from $E_{r} = 0 to 1$ MeV are studied with the ${}^{23}{Na} (d, p) {}^{24}{Na}$ reaction at $E_{d} = 11.0$ MeV using a biased quadrupole spectrometer. Fractionated single-particle states are identified via their forward angle cross sections, using distorted wave Born-approximation predictions with resonance state form factors for the residual ${}^{24}{Na}$ system. Spectroscopic results are compared with those from ( $n, n$ ) and/or ( $n, γ$ ) studies over the same region of excitation.

NUCLEAR REACTIONS ${}^{23}{Na} (d, p)$ , $E_{d} = 11$ MeV, measured $σ (θ)$ . ${}^{24}{Na}$ deduced levels, $l$ , $j$ , $π$ , spectroscopic factors. DWBA analysis, resolution 12 keV; comparison to neutron total $σ$ , ${}^{23}{Na}$ .

Angular distribution measurements for ${}^{14}C (d, p) {}^{15}C$ and the level structure of ${}^{15}C$

J. D. Goss, P. L. Jolivette, C. P. Browne, S. E. Darden, H. R. Weller, and R. A. Blue

Phys. Rev. C 12, 1730 (1975) - Published 1 December, 1975

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A 14 MeV deuteron beam was used to measure the angular distributions for the ${}^{14}C (d, p) {}^{15}C$ reaction leading to the two bound states and eight of the unbound states of ${}^{15}C$ . Vector-analyzing powers were measured for the elastic scattering and for the two bound states. Distorted wave Born approximation calculations were performed and spectroscopic factors were obtained for the two bound states. Calculations for stripping to unbound states using a resonance form factor and following the approach of Vincent and Fortune were compared with the angular-distribution data of the unbound states to obtain values of $J$ , $π$ , and neutron width $Γ_{n}$ . A strong $J$ dependence occurs in the calculated cross sections for stripping to unbound states.

NUCLEAR REACTIONS ${}^{14}C (d, p)$ , ( $\vec{d}, p$ ), ( $\vec{d}, d$ ), $E_{d} = 14.0$ MeV: measured $σ (θ)$ , $i T_{11} (θ)$ . ${}^{15}C$ levels deduced $J$ , $π$ , $S$ , and/or $\frac{Γ_{n}}{Γ_{s . p .}}$ .

High-spin states in ${}^{66}{Zn}$

J. F. Bruandet, M. Agard, A. Giorni, J. P. Longequeue, C. Morand, and Tsan Ung Chan

Phys. Rev. C 12, 1739 (1975) - Published 1 December, 1975

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The structure of ${}^{66}{Zn}$ has been investigated by studying the yield functions, angular distributions, and coincidence relationships of the $γ$ rays emitted during bombardment of an enriched ${}^{64}{Ni}$ foil by $α$ particles of medium energy (27 MeV). Spins up to 10h were assigned to observed states.

NUCLEAR REACTIONS ${}^{64}{Ni} (α, 2 n γ)$ , $E_{α} = 22 - 40$ MeV; measured $γ$ , $γ - γ$ , $σ (E_{γ}, θ_{γ})$ , deduced decay scheme and $J$ for high-spin states. Enriched target, Ge(Li) detectors.

Systematics of the proton stripping reaction on ${}^{69, 71}{Ga}$ , ${}^{75}{As}$ , ${}^{79, 81}{Br}$ isotopes and nuclear structure of the Ge-Se isotopes

D. Ardouin, R. Tamisier, M. Vergnes, G. Rotbard, J. Kalifa, G. Berrier, and B. Grammaticos

Phys. Rev. C 12, 1745 (1975) - Published 1 December, 1975

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The ${}^{69}{Ga} ({}^{3}{He}, d) {}^{70}{Ge}$ and ${}^{75}{As} ({}^{3}{He}, d) {}^{76}{Se}$ reactions have been studied at 25 MeV incident energy using a split-pole spectrometer. The over-all resolution is 18-21 keV. Sixty-two ${}^{70}{Ge}$ levels, 16 of which observed for the first time, are populated below 5.2 MeV excitation energy. Seventy-one ${}^{76}{Se}$ levels are separated, 44 of which had never been observed. Angular distributions are obtained and comparison with distorted-wave-Born-approximation calculations allows parity assignment and spin limits for many levels. Spectroscopic factors are deduced for most of the observed transitions. In order to test our mixing of orbital momenta, the ${}^{69}{Ga} (α, t) {}^{70}{Ge}$ reaction has also been performed at 39.35 MeV incident energy. A cursory investigation of the ${}^{79, 81}{Br} ({}^{3}{He}, d)$ reactions has been performed and systematics are drawn for the first excited levels between $N = 38 and 46$ . The model previously presented to account for the strong population of the ${}^{72}{Ge}$ $0_{2}^{+}$ level in our earlier study of ${}^{72}{Ge}$ with the same reaction is discussed and compared with the present results. From present and previously known experimental systematics, conclusions are drawn concerning the possibility of an oblate to prolate shape transition between $N = 36 and 46$ , the softness of the nuclei in the $N = 40$ region, and the noncollective structure of the $0_{2}^{+}$ state. Potential energy surfaces obtained by Hartree-Fock calculations using the Skyrme interaction are presented and confirm the above conclusions.

NUCLEAR REACTION ${}^{69, 71}{Ga} ({}^{3}{He}, d)$ , ${}^{75}{As} ({}^{3}{He}, d)$ , $E = 25$ MeV, measured $σ (θ)$ ; ${}^{79 - 81}{Br} ({}^{3}{He}, d)$ spectra; ${}^{69}{Ga} (α, t) {}^{70}{Ge}$ spectrum, $E = 39.35$ MeV; ${}^{70, 72}{Ge}$ , ${}^{76}{Se}$ , ${}^{80, 82}{Kr}$ deduced levels, $J$ , $π$ , $S$ ; deduced and presented systematics. NUCLEAR STRUCTURE ${}^{68 - 78}{Ge}$ ; calculated potential energy surfaces. Hartree-Fock method; Skyrme interaction.

Level structure of ${}^{54}{Mn}$ from the ${}^{56}{Fe} (p, {}^{3}{He})$ reaction at 40.2 MeV

A. Guichard, W. Benenson, and H. Nann

Phys. Rev. C 12, 1762 (1975) - Published 1 December, 1975

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The ${}^{56}{Fe} (p, {}^{3}{He}) {}^{54}{Mn}$ reaction has been studied at an incident energy of 40.2 MeV. Levels up to 6.16 MeV of excitation have been observed with an energy resolution of 25 keV. The experimental angular distributions have been analyzed with the distorted-wave Born approximation. Several $L$ assignments have been made which, when compared to other experimental data, permitted new spin assignments. A comparison with theoretical calculations is also presented.

NUCLEAR REACTIONS ${}^{56}{Fe} (p, {}^{3}{He})$ , $E_{p} = 40.2$ MeV; measured $σ (E_{{}^{3}{He}}, θ)$ ; enriched target. Deduced energies, $L$ values of ${}^{54}{Mn}$ levels.

Time-differential-free hyperfine field measurement at low recoil velocities

Y. Dar, J. Gerber, R. Loew, and J. P. Vivien

Phys. Rev. C 12, 1771 (1975) - Published 1 December, 1975

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A time-differential plunger technique has been used to observe the temporal attenuation of a $γ$ -ray angular distribution. Nuclei of ${}^{152}{Sm}$ were Coulomb excited by 3 and 4 MeV $α$ particles. A dominant static hyperfine interaction was observed from which a magnetic field at the nucleus of $2.6 \leq H (0) \leq 2.9$ MOe was deduced. This value is in agreement with the field calculated in the $LS$ scheme. The static interaction may originate in a number of one- and two-electron processes that occur at the target surface.

NUCLEAR REACTION: ${}^{152}{Sm} (α, α^{'})$ ; $E = 3; 4$ MeV, measured $α γ (θ, t)$ in vacuum. Deduced hyperfine field.

${}^{52}{Cr} (p, {}^{3}{He}) {}^{50}V$ reaction

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

Phys. Rev. C 12, 1780 (1975) - Published 1 December, 1975

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The energy levels in ${}^{50}V$ have been observed up to 3.9 MeV with the ${}^{52}{Cr} (p, {}^{3}{He})$ reaction at 40.2 MeV incident energy. Forty-five levels have been seen, and a distorted wave analysis permitted $L$ assignments for most of them. These results are compared to existing information and to ${f_{\frac{7}{2}}}^{n}$ shell-model calculations.

NUCLEAR REACTION ${}^{52}{Cr} (p, {}^{3}{He})$ , $E_{p} = 40.2$ MeV; measured $σ (E_{{}^{3}{He}}, θ)$ ; enriched target. Deduced energies, $L$ values of ${}^{50}V$ levels.

Total ( $p, n$ ) reaction cross-section measurements on ${}^{50}{Ti}$ , ${}^{54}{Cr}$ , and ${}^{59}{Co}$

S. Kailas, S. K. Gupta, M. K. Mehta, S. S. Kerekatte, L. V. Namjoshi, N. K. Ganguly, and S. Chintalapudi

Phys. Rev. C 12, 1789 (1975) - Published 1 December, 1975

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The total ( $p, n$ ) reaction cross sections, integrated over the $4 π$ solid angle and summed over all neutron groups, for ${}^{50}{Ti}$ , ${}^{54}{Cr}$ , and ${}^{59}{Co}$ have been measured as a function of proton energy in the energy range 3.0-4.9, 2.2-5.2, and 2.0-5.1 MeV in 5 keV steps, respectively. No strong isobaric analog resonances were seen in the data. The fluctuations in the excitation functions were analyzed to extract ${〈 Γ 〉}_{av}$ values using the "counting of maxima" method. The excitation functions, averaged over 100 keV energy interval reveal prominent intermediate width structures in the case of ${}^{50}{Ti}$ . All the three excitation functions were averaged over suitable energy intervals and compared with the total reaction cross sections calculated utilizing the optical model. The data on ${}^{59}{Co}$ and ${}^{54}{Cr}$ agreed, while the data on ${}^{50}{Ti}$ indicated a marked discrepancy with these optical model calculations. In the latter case, detailed Hauser-Feshbach (HF) and Hauser-Feshbach-Moldauer (HFM) calculations were carried out. The HFM calculations fit the data quite well. The importance of $σ (p, n)$ measurements in determining the imaginary potential of the optical model at sub-Coulomb energies has been indicated.

NUCLEAR REACTIONS ${}^{54}{Cr} (p, n)$ , $E = 2.2 - 5.2$ MeV; ${}^{50}{Ti} (p, n)$ , $E = 3.0 - 4.9$ MeV; ${}^{59}{Co} (p, n)$ , $E = 2 - 5.1$ MeV measured $σ (E)$ ; extracted ${〈 Γ 〉}_{av}$ ; optical model and Hauser-Feshbach analyses.

${}^{90}{Zr}$ and ${}^{92}{Zr}$ : Neutron total and scattering cross sections

P. Guenther, A. Smith, and J. Whalen

Phys. Rev. C 12, 1797 (1975) - Published 1 December, 1975

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Total neutron cross sections of ${}^{90}{Zr}$ and ${}^{92}{Zr}$ were measured from 0.9 to 5.5 MeV and elastic and inelastic neutron scattering cross sections from 1.8 to 4.0 MeV. The inelastic neutron excitations of six states in ${}^{90}{Zr}$ and more than 12 in ${}^{92}{Zr}$ were observed. The experimental results formed the basis of an optical-statistical model interpretation including considerations of resonance width fluctuation and interference and the behavior of the optical potential near $N = 50$ . Comparisons of measured and calculated cross sections suggested new spin assignments for a number of excited states.

NUCLEAR REACTIONS ${}^{90, 92}{Zr}$ : measured neutron total and elastic and inelastic scattering cross sections, incident energy 1.8-4.0 MeV, deduced spins, parities, and nuclear model.

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Physical Review C

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Long-lived states at high excitation energies in ${}^{8}{Be}$ and ${}^{10}B$

Mass of ${}^{8}C$

Investigation of the ${(d_{\frac{5}{2}})}^{2}$ and ( $d_{\frac{5}{2}} s_{\frac{1}{2}}$ ) two-particle configurations in ${}^{18}O$ using the ${}^{17}O (d, p) {}^{18}O$ reaction at 18 MeV

( $p, 2 p$ ) and ( $p, p d$ ) reactions on ${}^{3}H$ at 45.6 MeV

Single proton transfer to ${}^{29, 30}P$ states

Isospin mixing in nuclear resonance levels

( ${}^{3}{He}, 2 p$ ) reaction on ${}^{208}{Pb}$

Investigation of giant resonances as doorway states in inelastic nucleon scattering from ${}^{12}C$

Study of the ${}^{21}{Ne} (t, p) {}^{23}{Ne}$ reaction

Polarization in neutron-proton scattering at 29.6 MeV

How important are two-step processes in ${}^{16}O ({}^{3}{He}, d) {}^{17}F$ ?

Neutron resonances in ${}^{24}{Na}$ via the ( $d, p$ ) reaction

Angular distribution measurements for ${}^{14}C (d, p) {}^{15}C$ and the level structure of ${}^{15}C$

High-spin states in ${}^{66}{Zn}$

Systematics of the proton stripping reaction on ${}^{69, 71}{Ga}$ , ${}^{75}{As}$ , ${}^{79, 81}{Br}$ isotopes and nuclear structure of the Ge-Se isotopes

Level structure of ${}^{54}{Mn}$ from the ${}^{56}{Fe} (p, {}^{3}{He})$ reaction at 40.2 MeV

Time-differential-free hyperfine field measurement at low recoil velocities

${}^{52}{Cr} (p, {}^{3}{He}) {}^{50}V$ reaction

Total ( $p, n$ ) reaction cross-section measurements on ${}^{50}{Ti}$ , ${}^{54}{Cr}$ , and ${}^{59}{Co}$

${}^{90}{Zr}$ and ${}^{92}{Zr}$ : Neutron total and scattering cross sections

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