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Alignment and misalignment of fragment spins in 255 MeV Ar+Bi deep inelastic reactions

C. Le Brun, J. F. Lecolley, F. Lefebvres, M. L'Haridon, A. Osmont, J. P. Patry, J. C. Steckmeyer, and R. Chechik

Phys. Rev. C 25, 3212(R) (1982) - Published 1 June, 1982

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Angular distribution of sequential fission fragment of the heavy reaction product in coincidence with the light reaction product in the deep inelastic collision of 255 MeV ${}^{40}{Ar}$ by ${}^{209}{Bi}$ has been measured. For the first time, an important increase of the out-of-plane angular distribution width is observed as a function of the in-plane angle. The spins extracted from our data show clearly that the rigid rotation limit of the two nuclei is reached. The spin misalignment is preferentially located in a plane perpendicular to the heavy recoil lab direction.

NUCLEAR REACTIONS Heavy ions, ${}^{209}{Bi}$ ( ${}^{40}{Ar}$ , $X$ ) $Y$ , $X$ =projectilelike fragment ( $Z$ and energy measurements), $Y$ =identified heavy recoil or its fission fragment, $E = 255$ MeV, measurement of the angular distribution of the heavy recoil fission fragments, study of the angular momentum transfer in this deeply inelastic reaction, deduced values of the heavy fragment spin components (aligned part and in reaction plane components) as a function of charge transfer and total kinetic energy loss.

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Behavior of secondary $α$ particles produced from relativistic heavy-ion collisions

P. L. Jain, M. M. Aggarwal, G. Das, and K. B. Bhalla

Phys. Rev. C 25, 3216(R) (1982) - Published 1 June, 1982

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The interaction mean free paths of $α$ particles in fragments emitted from two heavy-ion beams of ${}^{40}{Ar}$ and ${}^{56}{Fe}$ , at an energy of $\sim 2 A$ GeV have been measured and were found to be the same, within statistical errors, at all distances from their production points.

NUCLEAR REACTIONS $Ar (or Fe) + E_{m} \to α + X$ and mean free path of $α$ .

RAPID COMMUNICATION

Target mass dependence of isotensor double charge exchange: Evidence for deltas in nuclei

C. L. Morris, H. T. Fortune, L. C. Bland, R. Gilman, S. J. Greene, W. B. Cottingame, D. B. Holtkamp, G. R. Burleson, and C. Fred Moore

Phys. Rev. C 25, 3218(R) (1982) - Published 1 June, 1982

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Measurements of forward-angle cross sections for double charge exchange on ${}^{16}O$ , ${}^{28}{Si}$ , and ${}^{40}{Ca}$ at 164 MeV incident pion energy suggest an $A^{- \frac{4}{3}}$ dependence for the cross section. This $A$ dependence is shown to provide evidence for $Δ$ components in the nuclear wave function.

NUCLEAR REACTIONS ${}^{16}O$ ( $π^{+}$ , $π^{-}$ ), ${}^{28}{Si}$ ( $π^{+}$ , $π^{-}$ ), ${}^{40}{Ca}$ ( $π^{+}$ , $π^{-}$ ); $E_{π} = 164$ MeV; measured $σ (5 °)$ , and mass excesses for ${}^{28}S$ and ${}^{40}{Ti}$ , found $A^{- \frac{4}{3}}$ dependence for cross section.

RAPID COMMUNICATION

Evidence for local excitations of the nucleus from ${}^{58}{Ni}$ ( $α$ , $α^{'} p$ ) coincidence measurements at $E_{α}^{lab} = 140$ MeV

U. Bechstedt, H. Machner, A. Budzanowski, P. Jahn, and C. Mayer-Böricke

Phys. Rev. C 25, 3221(R) (1982) - Published 1 June, 1982

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Spectra of protons emitted in coincidence with inelastically scattered $α$ particles at $E_{α}^{lab} = 140$ MeV from ${}^{58}{Ni}$ were measured. Slopes of Maxwellians corresponding to three different energy transfers were evaluated in each case for eight proton emission angles. The obtained results provide evidence for a localized excitation of the target nucleus.

NUCLEAR REACTIONS ${}^{58}{Ni}$ ( $α$ , $α^{'} c$ ) $c = p, α$ , $E_{α} = 140$ MeV, measured $σ (E_{α^{'}}, θ_{α^{'}}, E_{c}, θ_{c})$ , deduced reaction mechanism.

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Evidence for signature-dependent transition rates at large rotational frequencies

G. B. Hagemann, J. D. Garrett, B. Herskind, G. Sletten, P. O. Tjøm, A. Henriquez, F. Ingebretsen, J. Rekstad, G. Løvhøiden, and T. F. Thorsteinsen

Phys. Rev. C 25, 3224(R) (1982) - Published 1 June, 1982

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The signature dependence of transition rates has been measured for the first time at and above the rotational frequency of the band crossing. The disappearance of an observed large signature dependence in both level energies and transition rates may be interpreted as a shape change. A large change in the transition rates in the band-crossing region and an apparent signature dependence of $Δ I = 1$ , $E 2$ transitions are difficult to understand within the available models.

NUCLEAR STRUCTURE ${}^{157}{Ho}$ ; measured $γ - γ$ coin, $I_{γ} (θ)$ ; deduced levels, $J$ , $π$ , $δ$ , branching ratios, $g_{K} - g_{R}$ .

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Measurement of the vector analyzing power $i T_{11}$ for the $π d \to 2 p$ reaction with a polarized target

G. R. Smith, J. Bolger, E. Boschitz, E. L. Mathie, G. Proebstle, M. Meyer, F. Vogler, and S. Mango

Phys. Rev. C 25, 3228(R) (1982) - Published 1 June, 1982

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The vector analyzing power $i T_{11}$ has been measured in the $π d \to 2 p$ reaction using a vector polarized deuteron target. The data consist of an angular distribution of $i T_{11}$ at $T_{π} = 256$ MeV, and a four point excitation function of $i T_{11}$ taken at a center of mass angle of 55°. The angular distribution has been fitted with associated Legendre polynomials.

NUCLEAR REACTIONS $π d \to 2 p$ measured $i T_{11}$ as function of angle and energy, $θ = 25 - 85$ °, $E = 180 - 320$ MeV.

RAPID COMMUNICATION

Nuclear medium effects in pion absorption potentials

S. C. Phatak

Phys. Rev. C 25, 3232(R) (1982) - Published 1 June, 1982

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Nuclear medium effects in pion absorption potentials, that are calculated by using a two-nucleon mechanism, are estimated in this work by including the modification of the pion propagator and $π NN$ absorption vertex. The results show that the imaginary part of $S$ -wave pion-absorption potential changes significantly when these effects are incorporated.

NUCLEAR REACTIONS Pion-absorption potential; nuclear-medium effects.

RAPID COMMUNICATION

Rotational bands in the u(3)-boson model

D. J. Rowe and G. Rosensteel

Phys. Rev. C 25, 3236(R) (1982) - Published 1 June, 1982

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It is shown how the u(3)-boson model with a nonscalar su(3) lowest-weight state can generate low-lying rotational bands and that it does so by the addition of vorticity degrees of freedom to the Bohr-Mottelson irrotational flow model. The model is applied to ${}^{20}{Ne}$ with a $(λ, μ) = (8, 0)$ lowest-weight state and compared both with experiment and with its fully microscopic $sp (3 R)$ counterpart. It is shown that one can easily obtain $B (E 2)$ values with the experimentally required enhancements over the simple su(3) model.

NUCLEAR STRUCTURE sp(3,R), sp(6,R), su(3), collective theory, boson models.

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Giant dipole resonance at very high spin

J. L. Egido and P. Ring

Phys. Rev. C 25, 3239(R) (1982) - Published 1 June, 1982

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The giant dipole resonance in a deformed rotating nucleus is studied within the framework of linear response theory. A fine structure possessing three peaks is found. For the case of ${}^{164}{Er}$ the splitting is discussed as a function of the angular momentum. The influence of the Coriolis force is investigated.

NUCLEAR STRUCTURE Giant resonances, high spin states, dipole state, cranked random-phase-approximation equations, fragmentation width.

RAPID COMMUNICATION

$α$ -particle $D$ -state effects in ( $d$ , $α$ ) reactions

F. D. Santos, S. A. Tonsfelt, T. B. Clegg, E. J. Ludwig, Y. Tagishi, and J. F. Wilkerson

Phys. Rev. C 25, 3243(R) (1982) - Published 1 June, 1982

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It is shown that the tensor analyzing powers for ( $d$ , $α$ ) reactions are senstive to the $D$ -state component in the $α$ -particle wave function. The $D$ - to $S$ -state asymptotic ratio extracted from $T_{20}$ and $T_{22}$ data in $J = L \pm 1$ transitions is discussed using an $α$ -particle $D$ state generated with the Jackson and Riska model.

NUCLEAR REACTIONS Polarization ${}^{32}S$ , ${}^{36, 38}{Ar}$ ( $\vec{d}$ , $α$ ), $E = 16$ MeV; measured $A_{xx}$ , $A_{yy}$ ; deduced effect of $α$ -particle $D$ state.

Multi-quark cluster effect on ${}^{3}{He}$ and ${}^{4}{He}$ form factors

Mikio Namiki, Keisuke Okano, and Noriyuki Oshimo

Phys. Rev. C 25, 2157 (1982) - Published 1 May, 1982

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A multi-quark theoretical approach to ${}^{3}{He}$ and ${}^{4}{He}$ form factors based on the relativistic harmonic oscillator quark model is presented to reproduce those experimental data at large momentum transfers, which have not so far been explained in terms of ordinary nuclear physics.

NUCLEAR REACTIONS Calculated elastic electromagnetic form factors of ${}^{3}{He}$ , ${}^{4}{He}$ , $Q^{2}$ up to 3.5 and 2.5 ${(G e V / c)}^{2}$ , respectively. Multiquark cluster effect.

Positive pion photoproduction from ${}^{10}B$ and ${}^{16}O$

V. DeCarlo and N. Freed

Phys. Rev. C 25, 2162 (1982) - Published 1 May, 1982

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Differential and total cross sections for the reactions ${}^{10}B$ ( $γ$ , $π^{+}$ ) ${}^{10}{Be}$ and ${}^{16}O$ ( $γ$ , $π^{+}$ ) ${}^{16}N$ are calculated within the distorted wave impulse approximation and compared to experiment and to the results of similar calculations with different versions of the elementary photoproduction amplitudes, nuclear wave functions, and $π$ -nucleus optical potentials. Although the calculated results are in fairly good agreement with each other, discrepancies with experiment are much in evidence.

NUCLEAR REACTIONS ${}^{10}B$ ( $γ$ , $π^{+}$ ) ${}^{10}{Be}$ , ${}^{16}O$ ( $γ$ , $π^{+}$ ) ${}^{16}N$ . Calculated $\frac{d σ}{d Ω}$ , $σ$ ; compared with experiment, other calculations.

${}^{7}{Li}$ ( $d$ , $p$ ) ${}^{8}{Li}$ reaction cross section near 0.78 MeV

A. J. Elwyn, R. E. Holland, C. N. Davids, and W. Ray, Jr.

Phys. Rev. C 25, 2168 (1982) - Published 1 May, 1982

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The total cross section for the ${}^{7}{Li}$ ( $d$ , $p$ ) ${}^{8}{Li}$ reaction has been obtained at four energies near 0.78 MeV from measurements of the differential cross sections for the outgoing protons at laboratory angles between 20° and 155°. The average value, 146±13 mb at an average deuteron energy of 0.781 MeV, is about 20% lower than the weighted mean of all previous absolute measurements. It is, however, in agreement with two other completely independent measurements, and the three experiments together provide a consistent (but lower) value for this important cross section.

NUCLEAR REACTIONS ${}^{7}{Li}$ ( $d$ , $p$ ) ${}^{8}{Li}$ , $E_{d} = 0.684 - 0.896$ MeV; enriched ${}^{7}{Li}$ F target; measured $σ (E_{d}, θ)$ , $σ (E_{d})$ , at $E_{d} ≃ 0.781$ MeV, $σ (E_{d}, 50 °)$ at $E_{d} = 0.684 - 0.896$ MeV.

Absolute cross section for ${}^{7}{Li}$ ( $d$ , $p$ ) ${}^{8}{Li}$ and solar neutrino capture rates

B. W. Filippone, A. J. Elwyn, W. Ray, Jr., and D. D. Koetke

Phys. Rev. C 25, 2174 (1982) - Published 1 May, 1982

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The absolute total cross section for the ${}^{7}{Li}$ ( $d$ , $p$ ) ${}^{8}{Li}$ reaction has been measured between 0.60 and 1.2 MeV by counting the beta-delayed alpha particles from ${}^{8}{Be}$ *. The cross section at the peak of the 0.77-MeV resonance was measured to be 148±12 mb in good agreement with the new measurement of Elwyn et al. but disagreeing with several previous experiments. The effects of changes in this cross section on the calculation of solar neutrino captures rates is discussed.

NUCLEAR REACTIONS ${}^{7}{Li}$ ( $d$ , $p$ ) ${}^{8}{Li}$ , $E_{d} = 0.6 - 1.2$ MeV; measured $σ (E)$ , ${}^{8}{Le}$ delayed $α$ particles; enriched targets; calculated ${}^{37}{Cl}$ solar neutrino capture rates.

Inclusion of deuteron and alpha-particle collisions in intranuclear cascade calculations

G. J. Mathews, B. G. Glagola, R. A. Moyle, and V. E. Viola, Jr.

Phys. Rev. C 25, 2181 (1982) - Published 1 May, 1982

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An intranuclear cascade model generalized to allow deuteron and alpha-particle collisions during the cascade is discussed. A comparison of calculations is presented for nucleon-induced cascades with and without clusters present in the target nucleus and the effects of clustering are inferred. Alpha-particle-induced collisions are studied in detail and compared with experimental data. It is found that many features of alpha-particle-induced reactions can be well understood with this model. Possible shortcomings and directions of future improvements in the code are highlighted.

NUCLEAR REACTIONS Intranuclear cascade models; effects of including $d$ and $α$ as incident projectiles or preformed clusters.

Positive energy Weinberg states for the solution of scattering problems

G. Rawitscher

Phys. Rev. C 25, 2196 (1982) - Published 1 May, 1982

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Positive energy Weinberg states are defined and numerically calculated in the presence of a general complex Woods-Saxon potential. The numerical procedure is checked for the limit of a square well potential for which the Weinberg states and the corresponding eigenvalues are known. A finite number $M$ of these (auxiliary) positive energy Weinberg states are then used as a set of basis functions in order to provide a separable approximation of rank $M$ , $V_{M}$ , to a potential $V$ , and also to the scattering matrix element $S$ which obtains as a result of the presence of $V$ , $S_{M}$ . Both $V_{M}$ and $S_{M}$ are obtained by means of algebraic manipulations which involve the matrix elements of $V$ calculated in terms of the auxiliary positive energy Weinberg states. Next, expressions are derived which enable one to iteratively correct for the error in $V - V_{M}$ . These expressions are a modified version of the quasiparticle method of Weinberg. The convergence of $S_{M}$ to $S$ , as well as the first order iteration of the error in $S_{M}$ , is examined as a function of $M$ for a numerical example which uses a complex Woods-Saxon potential for $V$ and assumes zero angular momentum. With $M = 5$ and one iteration an error of less than 10% in $S$ is achieved; for $M = 8$ the error is less than 1%. The method is expected to be useful for the solution of large systems of coupled equations by matrix techniques or when a part of the potential is nonlocal.

NUCLEAR REACTIONS Scattering theory, expansions on a basis set of positive energy Weinberg states, removal of truncation error by the quasiparticle method. Normal mode effective scattering channels.

Neutron-deuteron analyzing power measurements at 50 MeV. I. Backward angles

J. L. Romero, J. L. Ullmann, F. P. Brady, J. D. Carlson, D. H. Fitzgerald, A. L. Sagle, T. S. Subramanian, C. I. Zanelli, N. S. P. King, M. W. McNaughton, and B. E. Bonner

Phys. Rev. C 25, 2214 (1982) - Published 1 May, 1982

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The analyzing power of polarized 50 MeV neutrons on deuterons has been measured for center-of-mass angles between 90° and 150°. The data, combined with forward angle measurements, are compared with recent $\vec{p} + d$ analyzing power measurements at 49.3 MeV and also with a three-body calculation at 46.3 MeV.

NUCLEAR REACTIONS ${}^{2}H$ ( $\vec{n}$ , $n$ ) ${}^{2}H$ , $E = 50.0$ MeV; measured $A_{y} (θ)$ from 89.7° to 149.8°, about every 5° c.m.

Neutron-deuteron analyzing power measurements at 50 MeV. II. Forward angles

J. W. Watson, R. Garrett, F. P. Brady, D. H. Fitzgerald, J. L. Romero, J. L. Ullmann, and C. I. Zanelli

Phys. Rev. C 25, 2219 (1982) - Published 1 May, 1982

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$\vec{n}$ + ${}^{2}H$ analyzing powers were measured at 50 MeV for 8 laboratory scattering angles between 25° and 65° ( $37 ° < θ_{c . m .} < 92 °$ ). No previous measurements for this angular range and energy exist. 50 MeV polarized neutrons from the $d + t \to \vec{n} + α$ reaction were scattered from a $C_{7}$ $D_{16}$ scintillating target, and detected with NE213 neutron detectors. This data, combined with backward angle measurements, are compared with a three-body neutron-deuteron calculation by Stolk and Tjon at 46.3 MeV.

NUCLEAR REACTIONS ${}^{2}H$ ( $\vec{n}$ , $n$ ) ${}^{2}H$ , $E = 50.0$ MeV; measured $A_{y} (θ)$ from 37.6° to 92.5°, about every 7° c.m.

Positive pion production from the bombardment of ${}^{9}{Be}$ with 200, 225, and 250 MeV polarized protons

E. G. Auld, G. Jones, G. J. Lolos, E. L. Mathie, P. L. Walden, and R. B. Taylor

Phys. Rev. C 25, 2222 (1982) - Published 1 May, 1982

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The analyzing power angular distributions $A_{y} (θ)$ for the ${}^{10}{Be}_{g . s .}$ as well as the ${}^{10}{Be}_{3.37}$ * state transitions from the ${}^{9}{Be}$ ( $\vec{p}$ , $π^{+}$ ) ${}^{10}{Be}$ reaction are reported as a function of incident proton energy from 200 to 250 MeV. Instead of the dramatic dependence on energy characterizing the ${}^{12}C$ ( $\vec{p}$ , $π^{+}$ ) ${}^{13}C$ reaction, the analyzing power for the present reaction shows little variation with energy. At energies above 200 MeV the analyzing power angular distributions exhibited by the ( $\vec{p}$ , $π^{+}$ ) reactions on ${}^{9}{Be}$ and ${}^{12}C$ are markedly different, unlike the earlier observations at 200 MeV where the distribution was essentially the same.

NUCLEAR REACTIONS ${}^{9}{Be}$ ( $\vec{p}$ , $π^{+}$ ) ${}^{10}{Be}_{g . s .}$ and ${}^{10}{Be}_{3.37}$ *, polarized protons, $T_{p} = 200 - 250$ MeV, measured $A_{y} (θ)$ for ${}^{10}{Be}_{g . s .}$ and ${}^{10}{Be}_{3.37}$ * transitions.

Nuclear excitation by the inelastic photoelectric effect

K. Pisk, M. Krčmar, A. Ljubičić, and B. A. Logan

Phys. Rev. C 25, 2226 (1982) - Published 1 May, 1982

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The possibility of a nucleus being excited during an interaction involving an incident photon, a bound orbital electron, and the nucleus has been investigated. In this inelastic photoelectric effect the angular distribution of the ejected photoelectrons has been calculated and the dependence of the total cross section on the photon energy and the nuclear excitation energy has been investigated.

NUCLEAR REACTIONS Calculated probability of nuclear excitation in interaction involving incident photon and bound atomic electron. Dependence of $σ$ on $Z$ , $E_{γ}$ , and photoelectron emission angle $θ$ studied.

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Recent Issues

Alignment and misalignment of fragment spins in 255 MeV Ar+Bi deep inelastic reactions

Behavior of secondary $α$ particles produced from relativistic heavy-ion collisions

Target mass dependence of isotensor double charge exchange: Evidence for deltas in nuclei

Evidence for local excitations of the nucleus from ${}^{58}{Ni}$ ( $α$ , $α^{'} p$ ) coincidence measurements at $E_{α}^{lab} = 140$ MeV

Evidence for signature-dependent transition rates at large rotational frequencies

Measurement of the vector analyzing power $i T_{11}$ for the $π d \to 2 p$ reaction with a polarized target

Nuclear medium effects in pion absorption potentials

Rotational bands in the u(3)-boson model

Giant dipole resonance at very high spin

$α$ -particle $D$ -state effects in ( $d$ , $α$ ) reactions

Multi-quark cluster effect on ${}^{3}{He}$ and ${}^{4}{He}$ form factors

Positive pion photoproduction from ${}^{10}B$ and ${}^{16}O$

${}^{7}{Li}$ ( $d$ , $p$ ) ${}^{8}{Li}$ reaction cross section near 0.78 MeV

Absolute cross section for ${}^{7}{Li}$ ( $d$ , $p$ ) ${}^{8}{Li}$ and solar neutrino capture rates

Inclusion of deuteron and alpha-particle collisions in intranuclear cascade calculations

Positive energy Weinberg states for the solution of scattering problems

Neutron-deuteron analyzing power measurements at 50 MeV. I. Backward angles

Neutron-deuteron analyzing power measurements at 50 MeV. II. Forward angles

Positive pion production from the bombardment of ${}^{9}{Be}$ with 200, 225, and 250 MeV polarized protons

Nuclear excitation by the inelastic photoelectric effect

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