Recent Articles

Many-body forces and the binding energy of high-density nuclear matter

Bruce H. J. McKellar and R. Rajaraman

Phys. Rev. C 10, 871 (1974) - Published 1 August, 1974

Show Abstract

The total contribution of all intrinsic pion-exchange many-body forces to the binding energy of nuclear matter is obtained in terms of an integral equation, the kernel of which includes the effect of pairwise correlations between the nucleons. This integral equation is solved for simple cases of the $π N$ interaction, and it is found that the resulting contribution to the energy increases rapidly as a function of the density, even in the presence of correlations. However, at very high densities we find that for a large class of many-body potentials the correlations completely suppress the contribution to the energy of forces involving four or more nucleons.

Hypertriton as a test of theoretical hyperon-nucleon potentials

B. F. Gibson and D. R. Lehman

Phys. Rev. C 10, 888 (1974) - Published 1 August, 1974

Show Abstract

A separable potential approximation to recent meson theoretic hyperon-nucleon potentials is made such that the low energy scattering parameters are reproduced. The resulting charge asymmetric potentials describing the $Λ - p$ and $Λ - n$ singlet and triplet interactions are used in a Faddeev-type calculation of the hypertriton binding energy. One particular one-boson exchange potential model, having effective ranges greater than 3 fm, gives a reasonable binding.

NUCLEAR STRUCTURE ${}_{Λ}^{3}H$ , $Y - N$ potentials, separable potential three-body calculation, $B_{Λ}$ .

Dynamic single-particle effects in fission

Y. Boneh and Z. Fraenkel

Phys. Rev. C 10, 893 (1974) - Published 1 August, 1974

Show Abstract

We calculate for a model nucleus the single-particle excitations in the transition from the saddle point to the scission point in the fission process. The model nucleus consists of a square well potential of finite depth filled with noninteracting "protons" and "neutrons." At every stage of the transition between the saddle point and scission point the shape of the potential surface is equal to the surface of the fissioning nucleus as predicted by the liquid-drop model but the depth of the potential is held constant. The rate of change of the nuclear surface is assumed to be equal to that predicted by the dynamical liquid-drop-model calculations of Nix. It is found that for this time scale there is a small probability for the particles to be raised to levels above the potential well and thus be emitted from the nucleus. The calculated number of emitted neutrons and protons is in qualitative agreement with the experimental results for the emission of scission neutrons and protons. However, there is a large energy transfer from the collective to the single-particle degrees of freedom and hence the transition cannot be considered adiabatic for this time scale. The inclusion in the model of a residual interaction is expected to reduce both the number of particles emitted and the energy transfer from the collective to single-particle degrees of freedom, thus making the transition more nearly adiabatic.

Many-particle states of the anisotropic oscillator

J. P. Draayer and S. A. Williams

Phys. Rev. C 10, 901 (1974) - Published 1 August, 1974

Show Abstract

The invariance under canonical transformations of the fundamental Cartesian coordinates and conjugate momenta commutators is used to show that the state labeling schemes of Elliott and Moshinsky are applicable to the case of many particles in an anisotropic harmonic oscillator potential. The relationship of the states obtained to the group theoretically equivalent isotropic harmonic oscillator states is investigated. The results reveal explicitly the collective nature of the particle-hole structure induced by the deformation.

NUCLEAR STRUCTURE Theory, many particle states, anisotropic (deformed) harmonic oscillator, relation to isotropic harmonic oscillator states.

Upper limit on the radiative width of the 9.64-MeV state of ${}^{12}C$

D. Chamberlin, D. Bodansky, W. W. Jacobs, and D. L. Oberg

Phys. Rev. C 10, 909 (1974) - Published 1 August, 1974

Show Abstract

An experimental upper limit for the branching ratio, $\frac{Γ_{rad}}{Γ}$ , for electromagnetic transitions from the 9.64-MeV state of ${}^{12}C$ has been established through a search for coincidences between inelastically scattered $α$ particles and the associated ${}^{12}C$ ions. It is concluded, at a one standard deviation confidence level, that $Γ_{rad}$ is less than 14 meV.

NUCLEAR STRUCTURE ${}^{12}C$ , 9.64-MeV state; measured upper limit on $\frac{Γ_{rad}}{Γ}$ . Helium burning.

Beta decay of ${}^{14}B$

D. E. Alburger and D. R. Goosman

Phys. Rev. C 10, 912 (1974) - Published 1 August, 1974

Show Abstract

A target of BeO, enriched to 94% in ${}^{10}{Be}$ , has been bombarded with 31-MeV ${}^{6}{Li}$ ions, and delayed activities were measured by means of a fast beam chopper and a NaI(Tl)-plastic $γ - β$ coincidence detecting system. $γ$ rays corresponding to the known activities ${}^{11}{Be}$ , ${}^{12}B$ , ${}^{13}B$ , ${}^{16}N$ , ${}^{20}F$ , and ${}^{20}{Na}$ were observed in coincidence with $β$ rays. In addition, the spectrum contained $γ$ rays of 6.1 and 6.7 MeV decaying with $T_{\frac{1}{2}} = 16.1 \pm 1.2$ msec. The 6.1-MeV $γ$ rays are in coincidence with $β$ rays having $E_{max} = 14.0 \pm 0.7$ MeV. This activity is assigned to ${}^{14}B$ produced in the ${}^{10}{Be} ({}^{6}{Li}, 2 p) {}^{14}B$ reaction. Based on the observed $γ$ -ray intensities the ${}^{14}B$ $β$ -ray branches to ${}^{14}C$ states at 6.09 ( $1^{-}$ ), 6.73 ( $3^{-}$ ), and 7.34 ( $2^{-}$ ) MeV are 81 ± 9%, ${8.6}_{- 4.0}^{+ 1.7}$ %, and <11%, respectively, where an allowance of 5% has been made for a probable ground-state $β$ -ray branch. It is deduced that ${}^{14}B$ has a spin-parity of $J^{π} = 2^{-}$ consistent with recent shell-model calculations. The experimental $log ft$ values for the β decay of ${}^{14}B$ are also in good agreement with theory.

RADIOACTIVITY ${}^{14}B$ : measured $T_{\frac{1}{2}}$ , $E_{γ}$ , $E_{β}$ , $γ - β$ coin; deduced $J^{π}$ of ${}^{14}B$ , $β$ branches, $log ft$ values; compared with theory.

Measurement of the magnetic moment of the 4.49-MeV ( $5^{-}$ ) state of ${}^{40}{Ca}$

R. Hensler, J. W. Tape, J. Matthews, N. Benczer-Koller, and Jack R. MacDonald

Phys. Rev. C 10, 919 (1974) - Published 1 August, 1974

Show Abstract

The $g$ factor of the 4.49-MeV ( $5^{-}$ ) state of ${}^{40}{Ca}$ has been measured in a time integral, external magnetic field, perturbed angular correlation experiment. A value of $g = 0.54 \pm 0.10$ was obtained. The angular rotation of the $p^{'} - γ$ correlation for the 4.49-MeV ( $5^{-}$ ) state was also measured for calcium nuclei implanted into a polarized iron foil. This measurement yields an average hyperfine magnetic field on calcium in iron which differs by a factor of 2 from the hyperfine field result obtained for ${}^{42}{Ca}$ (3.19-MeV, $6^{+}$ state) implanted in iron. The discrepancy in observed fields indicates a multiplicity of lattice sites for this system. The theoretical estimate of the $5^{-}$ state $g$ factor is in agreement with the experimental value.

NUCLEAR MOMENTS ${}^{40}{Ca} (p, p^{'} γ)$ ; measured $μ$ ( $5^{-}$ , 4.49-MeV level) and $H_{hyp}$ at Ca(Fe).

Charge symmetry of nuclear forces and nucleon-nucleon scattering experiments

L. G. Arnold

Phys. Rev. C 10, 923 (1974) - Published 1 August, 1974

Show Abstract

Comment on Pauli blocking in pion-nucleus scattering

H. J. Weber and J. M. Eisenberg

Phys. Rev. C 10, 925 (1974) - Published 1 August, 1974

Show Abstract

A modified solution is presented for the Chew-Low equations in nuclei, in the presence of Pauli blocking. The resulting scattering amplitude has more satisfactory behavior at low energies (for pionic atoms), while supporting use of a blocked amplitude in the region of the 3,3 resonance.

NUCLEAR SCATTERING $A$ $π, π$ , $E \sim 150 - 250$ MeV; calculated scattering amplitudes. Role of Pauli principle, dispersion theory.

Comment on precise single-scattering optical-potential fit to 1 GeV $p - {}^{4}{He}$ elastic scattering

R. H. Bassel and M. Rosen

Phys. Rev. C 10, 928 (1974) - Published 1 August, 1974

Show Abstract

The assertion in a recent letter by Saperstein of the failure of the Glauber scattering formalism in describing forward angle $p - {}^{4}{He}$ elastic scattering is pointed out to be incorrect. The single scattering optical potential described there is at best no better than the Glauber formalism in describing elastic $p$ -nucleus scattering at high energies.

NUCLEAR REACTIONS ${}^{4}{He} (p, p)$ ; $E = 1$ GeV, $σ (θ)$ . Watson single scattering potential and Glauber multiple scattering amplitude analyses equivalent.

Two-body short-range correlations and Coulomb matrix elements

G. F. Bertsch and S. Shlomo

Phys. Rev. C 10, 931 (1974) - Published 1 August, 1974

Show Abstract

Correlated Coulomb matrix elements are calculated by evaluating the appropriate $G$ matrices $G_{N + C}$ and $G_{N}$ which correspond to $V_{N} + V_{C}$ (nuclear + Coulomb) and $V_{N}$ potentials, respectively. Including the effect of the Pauli operator, we confirm the recent report by McCarthy and Walker that the effect of the two-body short-range correlations is small.

Classical view of the application of sum rules to inelastic form factors

G. F. Bertsch

Phys. Rev. C 10, 933 (1974) - Published 1 August, 1974

Show Abstract

RAPID COMMUNICATION

Delayed neutrons in the decay of ${}^{13}B$

D. E. Alburger and D. R. Goosman

Phys. Rev. C 10, 935(R) (1974) - Published 1 August, 1974

Show Abstract

$β$ -neutron time-of-flight techniques have been used to detect a third and previously unobserved neutron group in the decay of ${}^{13}B$ corresponding to a (0.022 ± 0.007)% $β$ -ray branch to the 9.90-MeV state of ${}^{13}C$ . The $log ft$ of 4.95 ± 0.12 for this branch agrees with the $log ft$ of 5.18 ± 0.14 for the analog ${}^{13}O$ → ${}^{13}N$ transition, and thus confirms a previous assignment of the 9.90-MeV ${}^{13}C$ state as the $J^{π} = {\frac{3}{2}}^{-}$ analog of the 9.52-MeV state in ${}^{13}N$ .

RADIOACTIVITY ${}^{13}B$ ; measured $β$ -neutron time-of-flight spectrum; deduced $β$ branches, $log ft$ ; compared with ${}^{13}O$ mirror decay.

RAPID COMMUNICATION

$π^{\mp}, π N$ knockout reactions on ${}^{14}N$ from 50 to 90 MeV

M. Zaider, J. Alster, D. Ashery, S. Cochavi, M. A. Moinester, and A. I. Yavin

Phys. Rev. C 10, 938(R) (1974) - Published 1 August, 1974

Show Abstract

The cross sections for the knockout reactions ${}^{14}N (π^{-}, π^{-} n) {}^{13}N$ and ${}^{14}N (π^{+}, π^{+} n + π^{0} p) {}^{13}N$ were measured over the energy range of 50 to 90 MeV by an activation method. The ratio of the cross sections $\frac{σ (π {}^{14}N)}{σ (π {}^{12}C)}$ at 70 and 90 MeV for both $π^{+}$ and $π^{-}$ is in good agreement with the similar ratio from high energy $p, p n$ reactions on the same targets. This is consistent with a quasifree pion-nucleus knockout picture. However, the ratio $\frac{σ (π^{-} {}^{14}N)}{σ (π^{+} {}^{14}N)}$ found to be about a third of the free pion-nucleon ratio, is in disagreement with the simple impulse approximation model.

NUCLEAR REACTIONS ${}^{14}N (π^{\mp}, π N) {}^{13}N$ , $E = 50, 70, 90$ MeV; measured $σ (E)$ .

RAPID COMMUNICATION

Pair excitation in ${}^{90}{Zr}$

R. H. Day and W. C. Parkinson

Phys. Rev. C 10, 941(R) (1974) - Published 1 August, 1974

Show Abstract

RAPID COMMUNICATION

Proposed excited band with reduced moment of inertia in ${}^{156}{Gd}$

C. Günther, H. Hübel, A. C. Rester, H. P. Blok, L. Hulstman, E. J. Kaptein, K. T. Knöpfle, and P. Turek

Phys. Rev. C 10, 943(R) (1974) - Published 1 August, 1974

Show Abstract

Excited states in ${}^{156}{Gd}$ were populated in the ${}^{158}{Gd} (p, t) {}^{156}{Gd}$ reaction with $E_{p} = 18.0, 20.5, and 27.6$ MeV. Our results do not confirm the existence of an excited rotational band with reduced moment of inertia compared to the ground state band which was suggested from a previous $p, t$ experiment at $E_{p} = 52$ MeV.

NUCLEAR REACTIONS ${}^{158}{Gd} (p, t)$ , $E_{p} = 18.0, 20.5, and 27.6$ MeV measured $σ (θ)$ . ${}^{156}{Gd}$ deduced levels. Enriched target.

RAPID COMMUNICATION

Resonance depolarization of ${}^{12}B$ implanted in metallic and semiconductor hosts

R. E. McDonald and T. K. McNab

Phys. Rev. C 10, 946(R) (1974) - Published 1 August, 1974

Show Abstract

Resonance depolarization measurements have been made on ${}^{12}B$ implanted in the semiconducting hosts silicon, germanium, and silicon carbide, and in the face-centered cubic metal hosts platinum, rhodium, palladium, gold, copper, aluminum, and sliver. The Knight shifts of ${}^{12}B$ in the metallic hosts have been obtained by comparison of the resonant frequencies in silicon and metallic hosts. The measured Knight shifts $\frac{Δ μ}{μ}$ are: [Pt; -10(3) × $10^{- 5}$ ], [Rh; 4(4) × $10^{- 5}$ ], [Pd; 11(4) × $10^{- 5}$ ], [Au; 54(3) × $10^{- 6}$ ], [Cu; 60(6) × $10^{- 5}$ ], [Al; 66(9) × $10^{- 5}$ ], and [Ag; 67(3) × $10^{- 5}$ ]. The effective ${}^{12}B$ magnetic moment is determined to be 1.002 82(2) $μ_{N}$ in Si, 1.002 91(2) $μ_{N}$ in Ge, and 1.002 87(2) $μ_{N}$ in SiC hosts.

NUCLEAR MOMENTS $μ ({}^{12}B)$ measured; resonance depolarization in Pt, Pd, Rh, Au, Ag, Cu, Al, Si, SiC, Ge hosts. Knight shifts measured.

RAPID COMMUNICATION

Search for weak beta and gamma branches in the beta decay of ${}^{59}{Fe}$

Ambuj Mukerji, D. Palazzo, and J. D. Ullman

Phys. Rev. C 10, 949(R) (1974) - Published 1 August, 1974

Show Abstract

The $β$ decay of ${}^{59}{Fe}$ was studied by $β - γ$ and $γ - γ$ coincidence methods for direct evidence of $β$ branches leading to higher excited states of ${}^{59}{Co}$ and to search for any transitions that had not yet been observed. Weak $β$ branches were observed to the 1.481- and 1.434-MeV states of ${}^{59}{Co}$ , confirming earlier indirect evidence from $γ$ -ray studies. No new $γ$ transitions were observed, but some useful limits were set on branching ratios of suspected transitions.

RADIOACTIVITY ${}^{59}{Fe}$ [from ${}^{58}{Fe} (n, γ)$ ]; measured $E_{β}$ , $E_{γ}$ , $I_{β}$ , $I_{γ}$ , $γ γ$ , $β γ$ ; deduced $J$ , $π$ .

RAPID COMMUNICATION

Isospin mixing in ${}^{12}C$ studied with the ${}^{14}N (d, α) {}^{12}C$ reaction at $E_{d} = 40$ MeV

A. van der Woude, W. J. Ockels, P. J. Pasma, and L. W. Put

Phys. Rev. C 10, 952(R) (1974) - Published 1 August, 1974

Show Abstract

The upper limit for the ratio of the cross sections for the isospin forbidden ${}^{14}N (d, α) {}^{12}C^{*}$ (15.11 MeV, $1^{+}$ , $T = 1$ ) transition and the isospin allowed ${}^{14}N (d, α) {}^{12}C^{*}$ (12.71 MeV, $1^{+}$ , $T = 0$ transition was found to be about 0.3% in the angular range from 6 to 10° (lab) and 0.5% at 40 and 50°.

NUCLEAR REACTION ${}^{14}N (d, α)$ , $E = 40$ MeV; measured $σ (E)$ at 8, 40, and 50°; upper limit for isospin mixing between 12.71 MeV $T = 0$ level and 15.11 MeV $T = 1$ level.

RAPID COMMUNICATION

Pion-nucleon absorption operator ambiguity

J. L. Friar

Phys. Rev. C 10, 955(R) (1974) - Published 1 August, 1974

Show Abstract

In agreement with recent results it is shown that the pion-nucleon absorption operator depends on the nucleon single-particle potential's Lorentz transformation properties. This is essentially the same result as for the nuclear magnetic moment problem, these terms being of relativistic order [i.e., ${(\frac{ν}{c})}^{2}$ corrections] in both problems. There exists a unitary equivalence of various forms of the absorption operator, but if handled consistently this leads to the same physical results.

Select page:

Physical Review C

Recent Articles

Filter

Recent Issues

Many-body forces and the binding energy of high-density nuclear matter

Hypertriton as a test of theoretical hyperon-nucleon potentials

Dynamic single-particle effects in fission

Many-particle states of the anisotropic oscillator

Upper limit on the radiative width of the 9.64-MeV state of ${}^{12}C$

Beta decay of ${}^{14}B$

Measurement of the magnetic moment of the 4.49-MeV ( $5^{-}$ ) state of ${}^{40}{Ca}$

Charge symmetry of nuclear forces and nucleon-nucleon scattering experiments

Comment on Pauli blocking in pion-nucleus scattering

Comment on precise single-scattering optical-potential fit to 1 GeV $p - {}^{4}{He}$ elastic scattering

Two-body short-range correlations and Coulomb matrix elements

Classical view of the application of sum rules to inelastic form factors

Delayed neutrons in the decay of ${}^{13}B$

$π^{\mp}, π N$ knockout reactions on ${}^{14}N$ from 50 to 90 MeV

Pair excitation in ${}^{90}{Zr}$

Proposed excited band with reduced moment of inertia in ${}^{156}{Gd}$

Resonance depolarization of ${}^{12}B$ implanted in metallic and semiconductor hosts

Search for weak beta and gamma branches in the beta decay of ${}^{59}{Fe}$

Isospin mixing in ${}^{12}C$ studied with the ${}^{14}N (d, α) {}^{12}C$ reaction at $E_{d} = 40$ MeV

Pion-nucleon absorption operator ambiguity

Filter

Recent Issues

Filter

Article Lookup

Enter a citation