Recent Articles

RAPID COMMUNICATION

Electroexcitation of collective $M 1$ resonances in ${}^{12}C$

E. Grecksch, W. Knüpfer, and M. G. Huber

Phys. Rev. C 15, 837(R) (1977) - Published 1 February, 1977

Show Abstract

The electroexcitation of high lying $M 1$ ( $T = 1$ ) resonances in ${}^{12}C$ has been investigated in a 1p1h- and 2p2h-configuration space. A concentration of this new kind of collective magnetic dipole states is found around 40 MeV, although the 2p2h admixtures lead effectively to a splitting of the excitation spectrum. From an inspection of the corresponding form factors it should be possible to study these collective states by inelastic electron scattering at high $q$ values ( $0.6 {fm}^{- 1} < q < 2 {fm}^{- 1}$ ).

NUCLEAR STRUCTURE ${}^{12}C$ , calculated $M 1$ resonances; included 1p1h, 2p2h configurations.

States of ${}^{34}P$

F. Ajzenberg-Selove, E. R. Flynn, S. Orbesen, and J. W. Sunier

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

Show Abstract

The ${}^{34}S (t, {}^{3}{He}) {}^{34}P$ reaction has been used to study the mass and low-lying excited states of ${}^{34}P$ , using 23 MeV tritons and a quadrupole-dipole-dipole spectrometer. The mass excess of ${}^{34}P$ is -24 545 (20) keV. Excited states have been observed at $E_{x} = 423, 1605, 2225, 2309, and (3345)$ keV (±10 keV). Spectra of the ${}^{24}{Mg} (t, {}^{3}{He}) {}^{24}{Na}$ reaction show no evidence for a previously reported state at $E_{x} = 2.46$ MeV in ${}^{24}{Na}$ .

NUCLEAR REACTIONS ${}^{34}S (t, {}^{3}{He})$ , ${}^{24}{Mg} (t, {}^{3}{He})$ , $E = 23.0$ MeV; measured $σ (θ)$ . ${}^{34}P$ deduced levels. New mass of ${}^{34}P$ . No evidence for previously reported state in ${}^{24}{Na}$ .

Microscopic calculation of the symmetry and Coulomb components of the complex optical-model potential

J. -P. Jeukenne, A. Lejeune, and C. Mahaux

Phys. Rev. C 15, 10 (1977) - Published 1 January, 1977

Show Abstract

We first investigate how the mass operator for symmetric and uncharged nuclear matter is modified in the presence of a Coulomb field and of neutron excess. Detailed calculations are performed with Reid's hard-core nucleon-nucleon interaction. They are carried out in the framework of the Brueckner-Hartree-Fock approximation, although some higher-order contributions to the low-density expansion of the mass operator are also considered. We relate the mass operator to the optical-model potential. We then use a local density approximation to construct the optical-model potential in a finite nucleus. We find that the half-depth radius of the isoscalar part of the calculated optical-model potential has the form $r_{V} A^{\frac{1}{3}}$ , where $A$ denotes the mass number. Since this property has always been assumed in the phenomenological analysis of the scattering data, a meaningful comparison is possible between our theoretical results for the symmetry and for the Coulomb components of the optical-model potential on the one hand, and the empirical values of these quantities as determined from the analysis of proton and neutron elastic scattering data or of direct charge exchange reactions on the other hand. The calculated depth of the symmetry potential is 11.5 MeV, but its range is larger than that of the isoscalar potential. The calculated value of the so-called Coulomb correction is larger than the one that is assumed in most empirical analyses. The combined effect of these features yields good overall agreement between the calculated and the empirical dependence on neutron excess of the optical-model potential.

NUCLEAR REACTIONS Calculation of the symmetry and Coulomb components of the optical-model potential from Reid's hard-core nucleon-nucleon interaction.

${}^{92}{Nb}$ using ${}^{89}Y (α, n γ) {}^{92}{Nb}$ and ${}^{92}{Zr} (p, n γ) {}^{92}{Nb}$

J. M. Davidson, D. M. Sheppard, P. W. Green, and J. A. Kuehner

Phys. Rev. C 15, 104 (1977) - Published 1 January, 1977

Show Abstract

The states of ${}^{92}{Nb}$ were studied using the reactions ${}^{89}Y (α, n γ) {}^{92}{Nb}$ and ${}^{92}{Zr} (p, n γ) {}^{92}{Nb}$ . The level and decay scheme of ${}^{92}{Nb}$ up to 1.6 MeV excitation was deduced from excitation function and $γ - γ$ coincidence data. Spins were deduced for many states from the analysis of $γ$ -ray angular distribution and $γ - γ$ angular correlation data. These include members of the $1 g_{\frac{9}{2}}^{π} \otimes 2 d_{\frac{5}{2}}^{ν}$ sextuplet at 286 ( $J = 3$ ) and 481 ( $J = 4$ ) keV excitation, and the ${(2 p_{\frac{1}{2}}^{π})}^{- 1} \otimes 2 d_{\frac{5}{2}}^{ν}$ doublet at 226 ( $J = 2$ ) and 390 ( $J = 3$ ) keV excitation.

NUCLEAR REACTIONS ${}^{89}Y (α, n γ)$ , $E = 7.0 - 12.5$ MeV, ${}^{92}{Zr} (p, n γ)$ , $E = 3.0 - 5.0$ MeV; measured $E_{γ}$ , $σ (E, E_{γ})$ , $σ (E_{γ}, θ_{γ})$ , $γ γ$ coincidence; ${}^{92}{Nb}$ deduced levels, $J$ , $π$ , $δ$ . Enriched and natural targets. Ge(Li) detectors.

Mass dependence of the ${}^{3}{He}$ optical potential at 40 MeV

S. M. Barr and R. M. DelVecchio

Phys. Rev. C 15, 114 (1977) - Published 1 January, 1977

Show Abstract

The elastic scattering of ${}^{3}{He}$ ions has been studied at 39.7 MeV from ${}^{12}C$ , ${}^{27}{Al}$ , ${}^{61}{Ni}$ , ${}^{105}{Pd}$ , and ${}^{197}{Au}$ at angles between 4° and 108°. The data are analyzed in terms of the optical model. A standard geometry is used to study the mass dependence of the real and imaginary well depths obtained from analysis of our data and that of others. The utility of a spin-orbit term is discussed. Continuous ambiguities of the geometrical parameters are examined. Improvements in the standard geometry are considered.

NUCLEAR REACTIONS ${}^{3}{He}$ elastic scattering from ${}^{12}C$ , ${}^{27}{Al}$ , ${}^{61}{Ni}$ , ${}^{105}{Pd}$ , ${}^{197}{Au}$ , $E = 39.7$ MeV, $σ (θ)$ measured from 4° to 108°; deduced optical model parameters.

Excitation of particle-vibration multiplets in the $A = 110$ region by two-neutron stripping reactions

R. E. Anderson, J. J. Kraushaar, I. C. Oelrich, R. M. DelVecchio, R. A. Naumann, E. R. Flynn, and C. E. Moss

Phys. Rev. C 15, 123 (1977) - Published 1 January, 1977

Show Abstract

The ${}^{103}{Rh}$ , ${}^{106, 108}{Pd}$ , and ${}^{107, 109}{Ag} (t, p)$ reactions have been studied at a bombarding energy of 17 MeV. Excitation energies and enhancement factors were obtained for a number of levels up to about 2.5 MeV excitation in the residual nuclei. The $L = 0$ transitions observed indicate that these nuclei are of a transitional character, though more closely resembling pairing rotational than pairing vibrational nuclei. The low-lying negative parity levels in the Ag nuclei appear to be well described as a ( $2 p_{\frac{1}{2}}$ ) proton weakly coupled to the appropriate core state in the even Pd cores. ${}^{105}{Rh}$ appears to display similar weak coupling characteristics. However, the higher-lying levels such as the $3^{-}$ based states are severely mixed with single particle levels and perhaps with other elementary modes of excitation as well.

NUCLEAR REACTIONS ${}^{103}{Rh}$ , ${}^{106, 108}{Pd}$ , ${}^{107, 109}{Ag} (t, p)$ , $E (t) = 17.0$ MeV, magnetic spectrograph, enriched targets; measured $σ (θ, E_{p})$ , excitation energies, DWBA analysis; ${}^{105}{Rh}$ , ${}^{108, 110}{Pd}$ , ${}^{109, 111}{Ag}$ deduced $L$ , $J$ , $π$ , enhancement factors; weak coupling model.

Nuclear levels in ${}^{161}{Dy}$ by the ( $d, p$ ), ( $d, t$ ), and ( $n, γ$ ) reactions

M. J. Bennett and R. K. Sheline

Phys. Rev. C 15, 146 (1977) - Published 1 January, 1977

Show Abstract

We have investigated the levels of the ${}^{161}{Dy}$ nucleus with ( $d, p$ ) and ( $d, t$ ) reactions using 12 MeV deuterons and a broad range magnetic spectrograph, with angular distribution analysis of the ( $d, t$ ) reaction using 15 MeV deuterons and a semiconductor detector telescope, and with the ( $n, γ$ ) reaction over the $γ$ -ray energy range from 25 to 6500 keV using Ge(Li) detectors and a large NaI annulus. The states observed are discussed in terms of the Nilsson model and comparisons are made with the levels in ${}^{163}{Er}$ and with theoretical calculations.

NUCLEAR REACTIONS ${}^{160}{Dy} (d, p)$ , $E_{d} = 12$ MeV; measured $E_{p}$ , $σ (θ)$ , $θ = 75 °, 95 °, 115 °$ ; ${}^{161}{Dy}$ deduced levels; DWBA analysis; enriched target; magnetic spectrograph. ${}^{162}{Dy} (d, t)$ , $E_{d} = 12$ MeV; measured $E_{t}$ , $σ (θ)$ , $θ = 85 °, 110 °$ ; ${}^{161}{Dy}$ deduced levels; DWBA analysis; enriched target; magnetic spectrograph. ${}^{162}{Dy} (d, t)$ , $E_{d} = 15$ MeV, measured $E_{t}$ , $σ (θ)$ , $θ = 30 - 100 °$ ; deduced $l$ values; ${}^{161}{Dy}$ deduced levels; DWBA analysis, enriched target; counter telescope. ${}^{160}{Dy} (n, γ)$ , $E_{n} = thermal$ ; measured $E_{γ}$ , $I_{γ}$ , $E_{γ} = 25 - 1600 keV and 4.5 - 6.5 MeV$ ; ${}^{161}{Dy}$ deduced levels; enriched target; Ge(Li) detectors. ${}^{161}{Dy}$ levels, $J$ , $π$ , Nilsson assignments.

States in ${}^{205}{Pb}$ excited via the ${}^{204}{Pb} (d, p)$ reaction. I. The "hole" states

C. F. Maguire, W. D. Callender, D. G. Kovar, and C. K. Bockelman

Phys. Rev. C 15, 161 (1977) - Published 1 January, 1977

Show Abstract

The spectrum of ${}^{205}{Pb}$ is studied with the ${}^{204}{Pb} (d, p)$ transfer reaction at incident energies of 13.0 and 20.0 MeV. Angular distributions are obtained for 15 of the known single-hole fragments in ${}^{205}{Pb}$ below an excitation energy of 2.56 MeV. Spectroscopic strengths are extracted and these results compared with three theoretical calculations. Two of these reproduce the total spectroscopic strengths and centroid energies for the neutron hole states rather well.

NUCLEAR REACTIONS ${}^{204}{Pb} (d, p)$ $0 < E_{x} \leq 2.56$ MeV; $E (d) = 13.0 and 20.0$ MeV; measured $σ (E_{p}, θ)$ , extracted $S_{lj}$ , and compared them with several theoretical calculations.

States in ${}^{205}{Pb}$ excited via the ${}^{204}{Pb} (d, p)$ reaction. II. The "particle" states

C. F. Maguire, D. G. Kovar, W. D. Callender, and C. K. Bockelman

Phys. Rev. C 15, 170 (1977) - Published 1 January, 1977

Show Abstract

The higher-lying states in ${}^{205}{Pb}$ $E_{x} \geq 2.57$ MeV) are examined by means of the ${}^{204}{Pb} (d, p)$ transfer reaction at incident energies of 13.0 and 20.0 MeV. In order to extract a reliable set of spectroscopic factors, a consistent set of distorted-wave Born approximation parameters is derived from analyses of new ${}^{208}{Pb} (d, p)$ data at $E_{d} = 13.0$ MeV, and by reanalysis of earlier ${}^{206, 208}{Pb} (d, p)$ data. By avoiding proton optical parameters based on data in an energy region later found to contain resonances, and by using a deuteron potential which corrects for deuteron breakup, ${}^{208}{Pb} (d, p)$ spectroscopic factors consistent to ±15% are obtained. The improved distorted-wave Born approximation parameters are used to assign orbital angular momentum ( $l_{n}$ ) values to a majority of 110 new levels in ${}^{205}{Pb}$ , most of them heretofore unknown. Significant fractions of the $1 i_{\frac{11}{2}}$ and the $1 j_{\frac{15}{2}}$ , and the majority of the $2 g_{\frac{9}{2}}$ , $3 d_{\frac{5}{2}}$ , $4 s_{\frac{1}{2}}$ , $2 g_{\frac{7}{2}}$ , and $3 d_{\frac{3}{2}}$ single-particle strengths are located. These strengths are found to be concentrated about the energy centroids. A previous theoretical calculation of spectroscopic strengths compares poorly with the experimental values.

NUCLEAR REACTIONS ${}^{204}{Pb} (d, p)$ , $E_{x} \geq 2.56$ MeV, $E_{d} = 13.0 and 20.0$ MeV, also ${}^{208}{Pb} (d, p)$ , $E_{d} = 13.0$ MeV; measured $σ (E_{p}, θ)$ , extracted $S_{lj}$ . Earlier ${}^{208}{Pb} (d, p)$ experiments at $E_{d} = 18.7, 20.0, and 24.8$ MeV and ${}^{206}{Pb} (d, p)$ at $E_{d} = 17.0$ MeV reanalyzed. ${}^{205}{Pb}$ results compared to weak-coupling theory.

Electric monopole transitions in ${}^{40}{Ca}$

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

Phys. Rev. C 15, 186 (1977) - Published 1 January, 1977

Show Abstract

The $E 0$ pair decay branching ratio ( $\frac{Γ_{π}}{Γ}$ ) for the 5.21-MeV $0^{+}$ fifth excited state of ${}^{40}{Ca}$ was measured. The state was excited by inelastic proton scattering. The $e^{-} - e^{+}$ pairs were detected in two $Δ E - E$ scintillation telescopes in coincidence with backscattered protons. A branching ratio limit of 1.4× $10^{- 3}$ was determined which corresponds to a monopole strength $ρ < 0.06$ . This result is consistent with theoretical descriptions which contain multiparticle excitations and core deformations. In addition, the branching ratio $R (\frac{(2_{2}^{+} \to 0_{2}^{+})}{(2_{2}^{+} \to 0_{1}^{+})}) = (2.1 \pm 0.1) \times 10^{- 2}$ for the decay of 5.25-MeV $2^{+}$ state was measured and corresponds to a $B (E 2) = (3.5 \pm 0.6) e^{2}$ ${fm}^{4}$ .

NUCLEAR REACTIONS ${}^{40}{Ca} (p, p^{'})$ , $E = 7 - 10$ MeV; ${}^{40}{Ca}$ , measured $E 0$ branching ratios. Deduced $E 0$ matrix elements. Natural targets.

Lifetimes of excited states of ${}^{92}{Mo}$

F. R. Metzger

Phys. Rev. C 15, 193 (1977) - Published 1 January, 1977

Show Abstract

Levels in ${}^{92}{Mo}$ at 1.509 ( $2^{+}$ ), 3.091 ( $2^{+}$ ), 3.925 ( $2^{+}$ ), 3.942, and 4.634 MeV have been excited by bremsstrahlung. Based on the angular distributions of the resonantly scattered $γ$ lines, spin one can be unambiguously assigned to the 3.942- and 4.634-MeV levels. The lifetimes deduced from the scattering yields are compared with the results of two sets of Doppler shift attenuation experiments which had been analyzed using different theories for the attenuation factor $F (τ)$ .

NUCLEAR REACTIONS ${}^{92}{Mo} (γ, γ)$ ; bremsstrahlung $2.0 \leq E_{e} \leq 5.1$ MeV; measured $σ (96 °)$ and $σ (126 °)$ ; deduced $J$ , $Γ$ . Enriched target.

$p$ -wave size resonances observed by the ( $p, n$ ) reaction for 2.6- to 7-MeV protons incident on isotopes of Sn

C. H. Johnson, J. K. Bair, C. M. Jones, S. K. Penny, and D. W. Smith

Phys. Rev. C 15, 196 (1977) - Published 1 January, 1977

Show Abstract

The ${}^{117, 118, 119, 120, 122, 124}{Sn} (p, n)$ cross sections were measured with ∼ 100-keV resolution for 2.6- to 7-MeV protons with systematic uncertainties of less than ± 1%. An exact sequence of broad maxima in the strength functions is observed with the energies at the peaks ranging from 5.45 MeV for ${}^{124}{Sn}$ to 6.15 MeV for ${}^{117}{Sn}$ . These are interpreted in terms of the $3 p$ quasibound proton state in the optical-model potential. Values of $V R^{2}$ for the real well at the resonance energies are determined unambiguously to ± 1% and range from 2120 MeV ${fm}^{2}$ for ${}^{117}{Sn}$ to 2215 MeV ${fm}^{2}$ for ${}^{124}{Sn}$ . For an assumed Woods-Saxon real-well geometry of radius $1.2 A^{\frac{1}{3}}$ fm and diffuseness 0.73 fm, the volume integral per nucleon is 513 ± 1 MeV ${fm}^{3}$ at each resonant maximum. The isotopic sequence of resonances appears to be unrelated to the asymmetry potential. The volume integral per nucleon of the surface absorptive potential is 80 ± 4 MeV ${fm}^{3}$ and the diffuseness is 0.4 ± 0.1 fm, where the uncertainties include ambiguities in the other model parameters. Comparisons with scattering at higher energies give evidence for an $l$ dependence in both the real and absorptive potentials. Comparison with the neutron $3 p$ size resonance near $A = 100$ is consistent with a 24-MeV asymmetry term in the real potential and a 15-MeV asymmetry term in the absorptive potential. Statistical model analyses of $γ$ -ray and neutron emission from the compound nuclei suggest that the compound temperatures are about a factor of 2 higher than expected. Evidence is found for broad structures at 1 to 1.5 MeV excitation in ${}^{118, 120}{Sb}$ . The Appendix includes an evaluation of levels below 2 MeV in ${}^{117}{Sb}$ and ${}^{119}{Sb}$ .

NUCLEAR REACTIONS ${}^{117, 118, 119, 120, 122, 124}{Sn} (p, n)$ , $E = 2.6 to 7$ MeV, resolution 70 to 180 keV, enriched targets. Measured total $σ_{p, n}$ . Deduced energy of $3 p$ quasibound proton states in ${}^{118, 119, 120, 121, 123, 125}{Sb}$ . Statistical model and optical-model analysis, deduced model parameters.

Electroexcitation of giant multipole resonances in ${}^{208}{Pb}$

Mamiko Sasao and Y. Torizuka

Phys. Rev. C 15, 217 (1977) - Published 1 January, 1977

Show Abstract

Electroexcitation of the nuclear continuum for ${}^{208}{Pb}$ at excitation energies up to 100 MeV has been measured at momentum transfers in the range from 0.45 to 1.2 ${fm}^{- 1}$ . Unfolding of the radiation tail was performed using a tail function which takes into account the multiple-photon emission effect. The spectra at these momentum transfers deviate significantly from the prediction of the Fermi-gas model but are consistent with the sum of the multipole strengths of the random-phase approximation; the excess cross section on the low excitation energy side indicates the excitation of multipole resonances. A series of ${}^{208}{Pb}$ spectra at low momentum transfers was expanded into $E 1$ , $E 2 (E 0)$ , $E 3$ , and higher multipole components using the $q$ dependence of the Tassie model for isoscalar modes and the Goldhaber-Teller or Steinwedel-Jensen model for isovector modes. The giant dipole resonance thus obtained is consistent with that from photoreactions. Isoscalar and isovector giant quadrupole resonances are seen, respectively, at 11 and 22.5 MeV and an octupole resonance at 16 MeV. A monopole resonance is suggested at 13.5 MeV. The reduced ${| 〈 r^{2} 〉 |}^{2}$ , $B (E 1)$ , $B (E 2)$ , and $B (E 3)$ consume most of the corresponding energy weighted sum rule if the $q$ dependences of the Tassie and Goldhaber-Teller models are assumed. The results with these models are consistent with the random-phase approximation.

NUCLEAR REACTION ${}^{208}{Pb} (e, e^{'})$ , measured ( $E_{e^{'}}, θ_{e^{'}}$ ), $E_{x} = 7.4 - 100$ MeV, $q = 0.45 - 1.2$ ${fm}^{- 1}$ , reduced ${| 〈 r^{2} 〉 |}^{2}$ , $B (E 1)$ , $B (E 2)$ , $B (E 3)$ for giant multipole resonances, multipole expansion analysis.

Scattering of 10.4 MeV polarized neutrons from bismuth and lead between 2° and 65°

A. H. Hussein, J. M. Cameron, S. T. Lam, G. C. Neilson, and J. Soukup

Phys. Rev. C 15, 233 (1977) - Published 1 January, 1977

Show Abstract

The polarization and differential cross sections for the scattering of 10.4 MeV neutrons from lead and bismuth are measured from 1.5° to 65°. No significant differences are found between the polarizations in the scattering at small angles in contrast to the situation reported at 2.45 MeV. The data over the complete angular range are reproduced using a standard optical potential with the addition of the long-range interaction between the neutron magnetic moment and the nuclear Coulomb field.

NUCLEAR REACTIONS Pb, $Bi (n, n)$ , $E_{n} = 10.4$ MeV; measured $σ (θ)$ and $P (θ)$ ; $θ = 1.5 ° - 65 °$ ; DWBA analysis.

Levels in ${}^{123}I$ and ${}^{125}I$ from ( ${}^{3}{He}$ , $d$ ) reactions

A. Szanto de Toledo, M. N. Rao, N. Ueta, and O. Sala

Phys. Rev. C 15, 238 (1977) - Published 1 January, 1977

Show Abstract

Proton states in ${}^{123}I$ and ${}^{125}I$ have been observed by means of the ${}^{123, 124}{Te} ({}^{3}{He}, d) {}^{123, 125}I$ reactions at a bombarding energy of 19.5 MeV. Results regarding spin assignments and spectroscopic factors are presented.

NUCLEAR REACTIONS ${}^{122, 124}{Te} ({}^{3}{He}, d)$ , $E = 19.5$ MeV; measured $σ (E_{d}, θ)$ , $θ = 10 ° - 90 °$ , $Δ θ = 5 °$ , enriched targets, $Δ E - E$ telescopes, resolution 35 keV. ${}^{123, 125}I$ deduced levels $l$ , $J$ , $π$ , $S$ ; DWBA analysis.

Particle decay from the giant resonance region of ${}^{40}{Ca}$

D. H. Youngblood, A. D. Bacher, D. R. Brown, J. D. Bronson, J. M. Moss, and C. M. Rozsa

Phys. Rev. C 15, 246 (1977) - Published 1 January, 1977

Show Abstract

The reactions ${}^{40}{Ca} (α, 2 α) {}^{36}{Ar}$ and ${}^{40}{Ca} (α, α p) {}^{39}K$ have been studied at 115-MeV bombarding energy in order to obtain the charged particle decay characteristics of the giant quadrupole resonance at $E_{x} = 18.0$ MeV. Energy and angle were measured for both outgoing light particles to completely define the kinematics. Weak proton decay to the $d_{\frac{3}{2}}$ ( $\frac{Γ_{p_{0}}}{Γ} = {0.08}_{- 0.03}^{+ 0.05}$ ) and $s_{\frac{1}{2}}$ ( $\frac{Γ_{p_{1}}}{Γ} = {0.22}_{- 0.08}^{+ 0.05}$ ) hole states of ${}^{39}K$ was observed from the giant quadrupole resonance while most of the decay proceeded to the region of the $d_{\frac{5}{2}}$ hole states. While the ( $α, 2 α$ ) reaction populated the ${}^{36}{Ar}$ ground state ( $O^{+}$ ), 1.97-MeV state ( $2^{+}$ ), and 4.18-4.44-MeV states ( $4^{+}$ , $3^{-}$ ), only upper limits could be established for α decay of the giant quadrupole resonance ( $\frac{Γ_{a_{0}}}{Γ} < 0.06$ ). Significant decay of the 14-MeV $L = 2$ state to the ground state of ${}^{36}{Ar}$ was observed ( $\frac{Γ_{a_{0}}}{Γ} \sim 0.9 \pm 0.2$ ).

NUCLEAR REACTIONS ${}^{40}{Ca} (α, α p)$ , ( $α, 2 α$ ), $E_{α} = 115$ MeV; measured $\frac{d^{4} σ}{d Ω_{α} d Ω_{p} d E_{α} d E_{p}}$ , $\frac{d^{4} σ}{d Ω_{α} d E_{α} d E_{α}}$ , ( $α - p$ ) angular correlation giant quadrupole resonance decay; deduced branching ratios, giant quadrupole resonance.

Search for the double-direct ( $p, 2 p$ ) reaction at 17 MeV

L. Shabason, B. L. Cohen, and T. Congedo

Phys. Rev. C 15, 260 (1977) - Published 1 January, 1977

Show Abstract

A method is developed for clearly distinguishing experimentally between ( $p, 2 p$ ) reactions which result from ( $p, p^{'}$ ) reactions followed by proton boiloff, and those in which the two protons are both emitted within ∼ $10^{- 22}$ sec in a direct reaction (referred to as "double direct"). Measurements involving coincidence detection and energy measurements on the two protons emitted at equal angles on opposite sides of the beam ( $θ_{2} = θ_{1}$ , $φ_{2} = φ_{1} + π$ ) indicate that at 17 MeV bombarding energy in the $A = 50 - 65$ region, the boiloff process is predominant with cross sections of the order of 1 mb for exciting ground states or low-lying excited states. The cross section for the double-direct process is not more than about 10 μb. A crude theoretical estimate indicates that this is about the correct order of magnitude.

NUCLEAR REACTION ${}^{51}V$ , ${}^{59}{Co}$ , ${}^{65}{Cu} (p, 2 p)$ , $E_{p} = 17$ MeV, exciting g.s., 1st excited; measured energy spectra, angular distributions, deduced cross sections for ( $p, p^{'}$ ) followed by boiloff, and for completely direct reactions.

Nuclear and Coulomb components in heavy-ion elastic and transfer reactions

R. C. Fuller and P. J. Moffa

Phys. Rev. C 15, 266 (1977) - Published 1 January, 1977

Show Abstract

Nuclear and Coulomb contributions to both heavy-ion elastic and transfer reactions have been isolated. The Coulomb contribution is essentially classical. The nuclear component is quantum mechanical, diffractive, and is described by a single complex angular momentum. The nuclear contribution to elastic scattering is related to a diffracted trajectory propagating around the interaction region.

NUCLEAR REACTIONS Heavy ion elastic and transfer reactions; Near-side and far-side decomposition of scattering amplitudes; decomposition into nuclear and Coulomb components; diffracted trajectory; ${}^{16}O$ + ${}^{48}{Ca}$ elastic scattering at $E_{lab} = 56$ MeV; ${}^{13}C$ + ${}^{94}{Mo}$ one nucleon transfer at $E_{lab} = 48.5$ MeV; ${}^{13}C$ + ${}^{60}{Ni}$ elastic scattering and one nucleon transfer at $E_{lab} = 60.8$ MeV.

Common optical potential and peripheral processes between $1 p$ -shell nuclei

C. W. Towsley, P. K. Bindal, K. -I. Kubo, K. G. Nair, and K. Nagatani

Phys. Rev. C 15, 281 (1977) - Published 1 January, 1977

Show Abstract

Elastic and inelastic scattering were measured for beams of 100-MeV ${}^{10}B$ and 155-MeV ${}^{14}N$ on targets of ${}^{12}C$ and ${}^{16}O$ . These data and previously measured one-nucleon transfer data for the same four incident channels were analyzed simultaneously. A single set of optical potential parameters, fitting all the elastic scattering data, was obtained. Distorted-wave Born approximation analyses of the inelastic and transfer reactions were also done with this potential, resulting in good fits to the data. The common features in all of these peripheral collisions are emphasized.

NUCLEAR REACTIONS NUCLEAR STRUCTURE ${}^{12}C$ ( ${}^{10}B$ , ${}^{10}B$ ), ${}^{12}C$ ( ${}^{10}B$ , ${}^{10}B$ ′), ${}^{16}O$ ( ${}^{10}B$ , ${}^{10}B$ ), ${}^{16}O$ ( ${}^{10}B$ , ${}^{10}B$ ′), $E = 100$ MeV; ${}^{12}C$ ( ${}^{14}N$ , ${}^{14}N$ ), ${}^{12}C$ ( ${}^{14}N$ , ${}^{14}N$ ′), ${}^{16}O$ ( ${}^{14}N$ , ${}^{14}N$ ), ${}^{16}O$ ( ${}^{14}N$ , ${}^{14}N$ ′), $E = 155$ MeV; measured $σ (θ)$ ; optical potentials, EFR-DWBA analyses extracted $β' s$ .

Level Scheme of ${}^{99}{Pd}$ and a possible high-spin cascade in ${}^{99}{Rh}$

W. F. Piel, Jr. and G. Scharff-Goldhaber

Phys. Rev. C 15, 287 (1977) - Published 1 January, 1977

Show Abstract

We have verified that a 493.7-, 911.0-, 879.5-, 648.9-, 805.2-, 264.0-keV $γ$ -ray cascade, produced by both ${}^{12}C$ + ${}^{91}{Zr}$ and ${}^{32}S$ + ${}^{70}{Ge}$ , occurs in ${}^{99}{Pd}$ by the observation both of coincidences between these $γ$ rays and palladium $K$ x rays and of $γ$ -ray excitation functions. Moreover, this cascade is found to be preceded by a (33.72±0.05)-keV transition. A second $γ$ -ray cascade with side chains also resulting from these bombardments is in addition produced by ${}^{10}B$ + ${}^{92}{Zr}$ . Therefore, this second cascade must occur in a nuclide with $Z \leq 45$ and not in ${}^{99}{Pd}$ , as has been proposed by other investigators. Arguments are given in favor of the conjecture that this second $γ$ -ray cascade populates the 4.7-h isomeric state of ${}^{99}{Rh}$ .

NUCLEAR REACTIONS ${}^{32}S$ + ${}^{70}{Ge}$ , $E = 110 - 140$ MeV; measured $γ - γ$ coin, $γ$ -x ray coin, $σ_{rcl} (E)$ , ${}^{12}C$ + ${}^{91}{Zr}$ , $E = 56 - 66$ MeV; measured $σ_{rcl} (E)$ , $W (t_{γ})$ by pulsed beam; ${}^{10}B$ + ${}^{92}{Zr}$ , $E = 40 - 55$ MeV; measured $σ_{rel} (E)$ ; ${}^{99}{Pd}$ , ${}^{99}{Rh}$ deduced levels, $J^{π}$ ; enriched targets, Ge(Li), Si(Li) detectors.

Select page:

Physical Review C

Recent Articles

Filter

Recent Issues

Electroexcitation of collective $M 1$ resonances in ${}^{12}C$

States of ${}^{34}P$

Microscopic calculation of the symmetry and Coulomb components of the complex optical-model potential

${}^{92}{Nb}$ using ${}^{89}Y (α, n γ) {}^{92}{Nb}$ and ${}^{92}{Zr} (p, n γ) {}^{92}{Nb}$

Mass dependence of the ${}^{3}{He}$ optical potential at 40 MeV

Excitation of particle-vibration multiplets in the $A = 110$ region by two-neutron stripping reactions

Nuclear levels in ${}^{161}{Dy}$ by the ( $d, p$ ), ( $d, t$ ), and ( $n, γ$ ) reactions

States in ${}^{205}{Pb}$ excited via the ${}^{204}{Pb} (d, p)$ reaction. I. The "hole" states

States in ${}^{205}{Pb}$ excited via the ${}^{204}{Pb} (d, p)$ reaction. II. The "particle" states

Electric monopole transitions in ${}^{40}{Ca}$

Lifetimes of excited states of ${}^{92}{Mo}$

$p$ -wave size resonances observed by the ( $p, n$ ) reaction for 2.6- to 7-MeV protons incident on isotopes of Sn

Electroexcitation of giant multipole resonances in ${}^{208}{Pb}$

Scattering of 10.4 MeV polarized neutrons from bismuth and lead between 2° and 65°

Levels in ${}^{123}I$ and ${}^{125}I$ from ( ${}^{3}{He}$ , $d$ ) reactions

Particle decay from the giant resonance region of ${}^{40}{Ca}$

Search for the double-direct ( $p, 2 p$ ) reaction at 17 MeV

Nuclear and Coulomb components in heavy-ion elastic and transfer reactions

Common optical potential and peripheral processes between $1 p$ -shell nuclei

Level Scheme of ${}^{99}{Pd}$ and a possible high-spin cascade in ${}^{99}{Rh}$

Filter

Recent Issues

Filter

Article Lookup

Enter a citation