D.A. Hutcheon

The elastic scattering of intermediate energy protons from 40Ca and 208Pb

Abstract Elastic scattering of protons from 40 Ca and 208 Pb has been studied using the MRS facility at TRIUMF. Cross section and analyzing power ( A y ) angular distributions to 50° in the center of mass have been measured for incident proton energies of 200, 300, 400 and 500 MeV. Comparisons of the experimental results are made with calculations based on relativistic and non-relativistic phenomenological models, and with relativistic and non-relativistic microscopic models. The differences between the results of the non-relativistic and relativistic models manifest themselves in the spin observables. They are found to be smaller in the phenomenological approach than in the microscopic one and they depend on energy.

Pulsed beam lifetime measurements in 64Cu, 59Ni, 65Zn, 45,47,49Ti and 47,49,50,51V

Abstract The lifetimes of several excited states in 64 Cu, 59 Ni, 65 Zn, 45,47,49 Ti and 47,49,50,51 V have been determined using a direct timing technique. Data for 64 Cu were obtained in order to provide reference γ-rays for use in the measurements on the Ti and V isotopes. Several states in 64 Cu were found to provide conveniently fast low-energy γ-ray decays : E ( ρ m ) are; 159 (29.8 ± 5.4), 278 ( 45 Ti 330 (1585 ± 20); 47 Ti 160 (301 ± 8), 1795 ( 49 Ti 1381 ( 47 V 88 (951±52), 146 (786 ± 95), 260 (78 ± 11); 49 V 90 (329 ± 19), 153 (28.71 ± 0.35 ns); 50 V 226( 51 V 320 (266 ± 9), 928 ( 59 Ni 340 (93 +- 10), 465(35 ± 18); 65 Zn 115 (641 ± 13), 207 (216 ± 10), 769 (

Quasi-free scattering of polarized protons☆

Abstract Cross section and analyzing power, energy-sharing spectra have been measured for the 16 O( p , 2p) reaction at an incident energy of 200 MeV for twenty-four different pairs of angles of the detected final-state protons. This general survey is intended to test the validity of the distorted wave impulse approximation (DWIA), particularly with respect to the predicted j -dependent analyzing power caused by the distorting optical potentials and nuclear spin-orbit coupling. Although the data in general confirm this j -dependence, agreement in detail between DWIA calculations and the analyzing power data becomes worse as the momentum of the recoiling nucleus increases. Predictably, the cross-section calculations show more sensitivity to the optical-model parameters than do the analyzing powers. Within the present limits imposed by scanty elastic scattering data, there seems to remain a choice between predicted ( p , 2p) cross sections which either are unreasonably large or which have the incorrect energy-sharing shapes. More comprehensive elastic scattering and total reaction cross section data are clearly needed.

Measurements of NN → dπ very near threshold: (I). The np → dπ0 cross section

Abstract We have measured cross sections for the reaction np→d π 0 at beam energies very near the pion-production threshold. The yield near threshold is 23% lower than the previously accepted value based on π + d→pp data. P-wave pion production was observed at energies as low as 1.5 MeV (c.m.) above threshold. There was no evidence of narrow πNN resonances in the energy range surveyed - 275 to 291 MeV, corresponding to pion c.m. momenta between 2 and 43 MeV/ c .

A study of 30P levels below 5 MeV

Abstract Spins of 16 excited states of 30 P have been investigated in conjunction with multipole mixing and branching ratios of a number of gamma transitions via the reaction 28 Si( 3 He, p γ ) 30 P. Spin assignments are consistent with those of other investigators in all cases except for the 4.921 MeV level whose branching ratios are also in disagreement with those previously reported. Assuming, as suggested by the present results, a transition from the 4.921 MeV level to the 0.680 MeV level rather than to the 0.709 MeV level, a unique assignment of J = 1 is made to the 4.921 MeV level. A new probable assignment of J = 1 has been made to the 3.736 MeV level. The previously unstudied 2.839, 3.836, 3.928 and 4.734 MeV levels have been assigned possible spin values together with branching ratios and multipole mixing ratios for their decay transitions. Branching ratios for transitions from the 3.736, 3.836, 3.928 and 4.501 MeV levels are in serious disagreement with those of previous studies. Using shell-model wave functions, calculations of lifetimes, multipole mixing ratios and branching ratios corresponding to five low-lying states showed agreement with experimental values for only the first two excited states.

An investigation of the 40Ca(p, 2p) reaction with polarised protons

Abstract The 40 Ca ( p , 2 p ) reaction has been observed at the TRIUMF facility using a 200 MeV polarised proton beam. Data were acquired at fourteen independent pairs of angles for separation energies from 0 to 100 MeV over a wide range of recoil momenta. Cross sections and analysing powers for the valence states (1 d 3 2 , 2 s 1 2 and 1 d 5 2 ) were extracted from the data. The results are compared with distorted wave impulse approximation (DWIA) calculations which incorporated the wave functions of EIton and Swift, spin-orbit dependent optical model potentials from Schwandt, and a half-off-shell prescription for the p-p scattering matrix element. The l = 2 states show strong j -dependence in the analysing power at most measured angles. DWIA calculations agree well with the analysing powers for equal and near equal angles in the forward direction. Unless nonlocality effects are included, however, the cross sections are overestimated (typically by 80%) when spectroscopic factors equal to the shell-model values of (2 J + 1) are used. The analysing power for the 2 s 1 2 state for small recoil momentum is reasonably predicted whether spin-orbit dependence in the optical model is included or not. For some kinematic conditions, peaks in the separation energy spectrum suggest the possible presence of 1 p 1 2 and 1 p 3 2 40 Ca single particle states at ∼12 MeV and ∼22 MeV excitation respectively.

Measurements of p-p and p-4He analyzing powers at medium energies

Abstract High precision proton-proton analyzing power measurements have been made at incident proton energies of 225, 327, and 520 MeV for θ lab = 17°, and at 205, 308, and 499 MeV for θ lab = 24°. The relative uncertainty is ± 1% for the results at 17° and ± 3% for the data at 24°. The p- 4 He analyzing power at θ lab = 15° was measured with ± 1–2% errors at 222, 325, and 518 MeV. These results can be used as accurate calibration standards for polarized proton beams and provide accurate polarization normalizations for phase shift analyses.

The reaction 2H(p,π+)3H at 470 and 500 MeV

Abstract Angular distributions of the cross section at 470 and 500 MeV and the analyzing power at 500 MeV incident proton energy are presented for the reaction 2 H ( p ,π + ) 3 H . The cross section and analyzing power measurements cover the respective angular ranges 10°

Large-angle measurements of the 4He(p, d) 3He reaction at intermediate energies☆

Abstract The differential cross section for the reaction 4 He (p, d) 3 He has been measured at incident proton energies of 275, 300, 350, 400, 440, and 500 MeV in the laboratory angular range between 144° and 168°. Polarization asymmetry has been observed served at 350, 400, and 500 MeV in the same angular range. The differential cross section is strongly backward peaked at all energies. The analyzing power is smaller than that for elastic p− 4 He elastic scattering. The differential cross section, similar in slope and magnitude to that for p− 3 He elastic scattering, indicates that deutron exchange may be the major component of the reaction mechanism.

Coriolis coupling between rotational bands in the nucleus 57Fe

Abstract The first five levels of 57Fe are considered to be the members of two rotational bands with K = 1 2 and K = 3 2 which are admixed due to Coriolis coupling. A reasonable set of rotational parameters are found to give an exact agreement with the energies of all known levels below 1 MeV excitation and to yield a fairly well-defined Nilsson model potential. The other single-particle levels in this potential are compared with higher levels. The single-particle wave functions are used to calculate the magnetic moments, quadrupole moments and M1 and E2 reduced transition probabilities for the low-lying levels. The model is found to give a fair description of all these properties.