Neutron-hole strength distributions in heavy nuclei: (II). The 144, 148, 152Sm(3He, α) 143, 147, 151Sm and the 144, 148, 150, 152, 154Sm(p,d) 143, 147, 149, 151, 153Sm reactions

Valence and deep-lying neutron-hole strengths corresponding to orbits near and well below the Fermi surface have been observed in high-resolution studies of the ^{144, 148, 152}Sm(³He, α) and of the ^{144, 148, 150, 152, 154}Sm(p, d) reactions at 70 and 42 MeV bombarding energy, respectively. The explored excitation energy range was 28 MeV for the (³He, α) experiment and about 12 MeV in the (p, d) study. Complete angular distributions have been measured in both cases and the data was analyzed within the framework of the distorted waves Born approximation theory of direct reactions.For the neutron closed shell target (¹⁴⁴Sm), in addition to the well-known fragmentation of the 2d_{$\text{5}\text{2}$} and 1g_{$\text{7}\text{2}$} valence-hole strength, a new bump observed around 7.6 MeV excitation energy is excited in both reactions. This structure corresponds to the 1g_{$\text{9}\text{2}$} inner-hole strength in ¹⁴³Sm and the analysis of the (³He, α) data suggests that more than 50% of the l = 4 strength can be found between 6 and 12 MeV. When one goes to the heavier Sm isotopes, the energy spacing between valence-hole states located above and just below the N = 82 shell decreases strongly and disappears in ¹⁵¹Sm as a result of increasing deformation.Combining good energy resolution and detailed analysis of the two reactions, rather complete spectroscopic information is obtained for the valence-hole strength distributions. With regard to inner-hole states, the energy spectra exhibit a narrow structure whose centroid energy decreases from 4.4 to 2.9 MeV when the mass number increases from A = 147 to A = 153. The main peak displays an asymmetric shape with an extremely large high-energy tail. The 1h_{$\text{11}\text{2}$} hole strength is split into the Nilsson Orbitals. The narrow bumps are found to carry a large fraction of the l = 5 and l = 2 hole strengths in ^{147,149,151,152}Sm isotopes. In the high-energy tail of the structures one observes overlapping and increasing spreading of the g_{$\text{7}\text{2}$}, 2d_{$\text{5}\text{2}$} and possibly 1g_{$\text{9}\text{2}$} inner-hole strengths due to the disappearance of the N = 82 shell gap between N = 83 and N = 89 neutron numbers. The experimental hole strengths distributions are compared where possible to the predictions of the quasiparticle-phonon nuclear model or to the simple Nilsson model.     

Study of 60Zn and 61Zn

The (¹²C, ¹⁰Be) and (¹²C, ⁹Be) reactions on ⁵⁸Ni were studied at 77 MeV. New levels were determined for both residual nuclei, ⁶⁰Zn and ⁶¹Zn. For ⁶¹Zn, levels and a new ground state mass were also measured with the ⁶⁴Zn(³He, ⁶He) reaction. A mass excess for ⁶¹Zn of ?56333±23 keV was obtained. Angular distributions for the ¹²C induced reactions are compared with finite range DWBA calculations and found to be insensitive to L? and J-transfer.     

Preparation and degradation of head-to-head PVC

The course of the chlorination reaction of cis-1,4-polybutadiene is dependent on the choice of solvent. When methylene chloride is used, a pure addition reaction of chlorine leads to a polymer with the structure of head-to-head, tail-to-tail PVC. The thermal stability of the head-to-head PVC polymer has been studied by thermal volatilization analysis, thermogravimetry, and evolved gas analysis for hydrogen chloride, and the changes in the ultraviolet (UV) spectrum of the polymer during degradation have been investigated. The head-to-head polymer has a lower threshold temperature of degradation than normal PVC, but reaches its maximum rate of degradation at a higher temperature for powder samples of the polymer under programmed heating conditions. Blends of head-to-head PVC with poly(methyl methacrylate) have also been degraded, and the presence of the head-to-head polymers, like that of normal PVC, results in depolymerization of the PMMA as soon as the dehydrochlorination reaction commences. The mechanism of degradation of head-to-head PVC is discussed.     

Study of the energy and charged multiplicity dependence of inclusiveπ− production in π−p interactions up to fermilab energies

Using new data from 100 $\text{GeV}\text{c π}{}^{\mathrm{?}}$ interactions, we find the energy dependence of the invariant cross-section in the target fragmentation (central) region to be consistent with an $\text{A + Bs}{}^{\mathrm{<mtext>?</mtext><mtext>1</mtext><mtext>2</mtext>}}\text{(C + Ds}{}^{\mathrm{<mtext>?</mtext><mtext>1</mtext><mtext>4</mtext>}}\text{)}$ behavior. The leading particle peak near x = + 1 exhibits a width in x which becomes smaller with increasing energy and an integrated cross section which is approximately energy independent.     

Epimorphisms and ℋ-coextensions

Conclusions Theorems 3.4 and 4.3 have consequences of a similar form: we have compact monoids built from objects in a smaller category of compact monoids, and an epimorphism in the larger category is surjective provided the induced morphism (in 3.4 the restriction to the idempotents) is surjective. In 3.2 and 3.3 we make use of the fact that for the smaller category CL this will always be the case. Thus 3.4 and 4.3 could be completed, in a sense, if we know more about epimorphisms of compact semilattices and about A-epimorphisms. As for 3.4, another type of completion would be an extension to the nonabelian case. Since it is not known (see [2], [17]) whether constructions analogous to those in 3.1 yield Hausdorff semi-groups for the non-Lawson case, this problem may be difficult.In closing, the author would like to thank Professor J. H. Carruth for his helpful advice and encouragement in the research leading to this paper.     

The 206, 204Pb(p, α)203, 201Tl reactions at 35 MeV

The ²⁰⁶Pb(p, α)²⁰³Tl and ²⁰⁴Pb(p, α)²⁰¹Tl reactions have been studied using 35 MeV protons. For both ²⁰³Tl and ²⁰¹Tl approximately 50 levels with excitation energies up to 4.0 MeV were identified and angular distributions of most of these states were measured. Cluster-model DWBA calculations were shown to produce excellent fits to the measured angular distributions. Using these calculations high-spin $\text{(j ≧}\text{15}\text{2}\text{)}$ states were found in both nuclei. The strengths, energies, and number of high-spin states excited in ²⁰¹Tl and ²⁰³Tl are compared with those observed in ²⁰⁵Tl in a previous study.