The optical potential of 6^{6}He in the eikonal approximation

The new data of the elastic scattering of $^{6}$He+$^{12}$C at about 40 MeV/nucleon are analyzed in the eikonal approximation. The $^{6}$He+$^{12}$C phase-shift function is evaluated completely without any {\it ad hoc} assumption by a Monte Carlo integration, which makes it possible to use a realistic 6-nucleon wave function for a halo nucleus $^{6}$He. The effect of the breakup of $^6$He on the elastic differential cross sections as well as the optical potential is studied at different energies from 40 to 800 MeV/nucleon. PACS number(s): 24.10.-i; 21.60.Ka; 25.60.Bx; 25.10.+s Keywords: Eikonal; Glauber; Monte Carlo; Halo; BreakupComment: 13 pages, 9 figure

Monte Carlo integration in Glauber model analysis of reactions of halo nuclei

Reaction and elastic differential cross sections are calculated for light nuclei in the framework of the Glauber theory. The optical phase-shift function is evaluated by Monte Carlo integration. This enables us to use the most accurate wave functions and calculate the phase-shift functions without approximation. Examples of proton nucleus (e.g. p-$^6$He, p-$^6$Li) and nucleus-nucleus (e.g. $^6$He$-^{12}$C) scatterings illustrate the effectiveness of the method. This approach gives us a possibility of a more stringent analysis of the high-energy reactions of halo nuclei.Comment: 20 pages, 8 figure

Breakup reaction models for two- and three-cluster projectiles

Breakup reactions are one of the main tools for the study of exotic nuclei, and in particular of their continuum. In order to get valuable information from measurements, a precise reaction model coupled to a fair description of the projectile is needed. We assume that the projectile initially possesses a cluster structure, which is revealed by the dissociation process. This structure is described by a few-body Hamiltonian involving effective forces between the clusters. Within this assumption, we review various reaction models. In semiclassical models, the projectile-target relative motion is described by a classical trajectory and the reaction properties are deduced by solving a time-dependent Schroedinger equation. We then describe the principle and variants of the eikonal approximation: the dynamical eikonal approximation, the standard eikonal approximation, and a corrected version avoiding Coulomb divergence. Finally, we present the continuum-discretized coupled-channel method (CDCC), in which the Schroedinger equation is solved with the projectile continuum approximated by square-integrable states. These models are first illustrated by applications to two-cluster projectiles for studies of nuclei far from stability and of reactions useful in astrophysics. Recent extensions to three-cluster projectiles, like two-neutron halo nuclei, are then presented and discussed. We end this review with some views of the future in breakup-reaction theory.Comment: Will constitute a chapter of "Clusters in Nuclei - Vol.2." to be published as a volume of "Lecture Notes in Physics" (Springer

Elastic and total reaction cross sections of oxygen isotopes in Glauber theory

We systematically calculate the total reaction cross sections of oxygen isotopes, $^{15-24}$O, on a $^{12}$C target at high energies using the Glauber theory. The oxygen isotopes are described with Slater determinants generated from a phenomenological mean-field potential. The agreement between theory and experiment is generally good, but a sharp increase of the reaction cross sections from ^{21}O to ^{23}O remains unresolved. To examine the sensitivity of the diffraction pattern of elastic scattering to the nuclear surface, we study the differential elastic-scattering cross sections of proton-^{20,21,23}O at the incident energy of 300 MeV by calculating the full Glauber amplitude.Comment: 9 pages, 8 figure

Combining ability for grain yield and yield components in local inbred lines and introduced open pollinated varieties of maize (Zea mays L)

ABSTRACT  The development of hybrids is the main objective of maize breeding. However, success depends largely on the identification of the best parents to ensure maximum combining ability. This study was conducted to estimate genetic variability and combining ability for grain yield and yield components of seven local inbred lines and four introduced open pollinated varieties of maize (Zea mays L.) across two irrigated locations, Medani and Matuq, Gezira, Sudan in 2008. The experiment was arranged in a randomized complete block design with three replicates. The traits measured were days to 50% tassel, plant height, ear length, ear diameter, hundred kernels weight and grain yield. Significant differences were observed among the parents and crosses for most of studied traits in both seasons. The crosses showed high genetic variability and tall plants than their parents which suggested some degree of hybrid vigor. The tallest hybrids across locations were T3 x L5 and T4 x L3. This indicates that the crosses were late maturing than their parents. The highest yielding hybrids had long ears and better shape, e.g., T2 x L1 and T1 x L7.The top five ranking crosses for grain yield across locations were T2 x L7 (3.45 t/ha), T1 x L2 (3.44 t/ha), T2 x LI (3.32 t/ha), T4 x L4 (3.30 t/ha) and T1 x L1 (3.13 t/ha).   The inheritance of most traits was controlled by non-additive gene action except ear height and grain yield. The best combiners for grain in Medani were T4, L4 and L5, while in Mutaq were L2, L4 and L6. The ratio of GCA to SCA variance for the most traits was less than one, suggesting that the inheritance was due to non additive gene effect with the exception of grain yield being more than one, indicating that inheritance of this trait was due to GCA effects, and was largely controlled by additive gene action in the base material. From these results it is recommended that parents T4, L1 and L6 to be used in recurrent selection, while, crosses T3 x L5, T1 x L5 and T4 x L6 to be tested in multi-locations trials for commercial utilization

Heterosis for grain yield and its components in topcross hybrids of maize

    Development of high yielding hybrids with high vigor is the ultimate objective of maize breeding and the success depends largely on the identification of the best parents to ensure maximum heterosis for hybrid production. This study was conducted to estimate genetic variability and heterosis of grain yield and yield components  of seven local inbred lines and four introduced open pollinated varieties of maize (Zea mays L.) across  two irrigated locations (Medani and Matuq) in 2008. The experiment was arranged in a randomized complete block design with three replicates. The traits measured were days to 50% tassel, plant height, ear length, ear diameter, hundred kernels weight and grain yield. The crosses showed high genetic variability and tall plants than their parents which suggested some degree of hybrid vigor. The tallest hybrids across locations were T3 x L5 and T4 x L3. This indicates that the crosses were late maturing than their parents. The highest yielding hybrids had long ears and better shape, e.g., T2 x L1 and T1 x L7.The top five ranking crosses for grain yield across locations were T2 x L7 (3.45 t/ha), T1 x L2 (3.44 t/ha), T2 x LI (3.32 t/ha), T4 x L4 (3.30 t/ha) and T1 x L1 (3.13 t/ha). The highest percentage of mid parent heterosis for grain yield in Medani, was given by T3 x L3 and T4x L4; in Matuq, by T1 x L5, T4 x L5 and T4 x L6 and across sites by T1 x L2 (59%), T3 x l2 (45%) and T3 x L6 (50%). These crosses can be recommended for future testing in multilocations trials for commercial utilization.    تحسين صفات الإنتاجية لمحصول الذرة الشامية هي الغاية المنشودة من خلال التربية لإنتاج الهجن والتي تعتمد على تحديد أفضل الآباء وأكثرها قوة لإنتاج الهجين. لذا أجريت هذه الدراسة لتقدير التباين الوراثي و قوة الهجين لأربعة سلالات تربية داخلية وسبعة أصناف مستقدمة مفتوحة التلقيح من الذرة الشامية (Zea mays L.) تحت ظروف ري مستدام، موسم 2008 .استخدم تصميم القطاعات العشوائية الكاملة بثلاثة مكررات لتنفيذ التجربة. الصفات التي تمت دراستها شملت 50% لعدد أيام الإزهار المذكر ، طول النبات، طول الكوز، حجم الكوز، وزن المائة حبة وإنتاجية الحبوب.أظهرت النتائج فروق معنوية لكل  الصفات في الموقعين وأكثر تباينا وراثياً في طول النبات وفترة النضج.  وجد أن الهجن متأخرة في الأزهار وفترة النضج مقارنة بالآباء. أما  طول وحجم صفات القندول فقد وجد أن لها أهمية كبرى في زيادة  الإنتاجية وأفضل الهجن هي T1 x L7 و T2 x L1  .أعلى الهجن إنتاجية هى 3.45) T2 x L7طن/هكتار) و 3.44) T1 x L2 طن/هكتار)  وT2 x LI(3.32 طن/هكتار) و T4 x L4( 3.30طن/هكتار) و T1 x L1(3.13طن/هكتار ). الهجن التي أظهرت أعلى قوة هجين في مدني هيT3 x L3 و   T4x L4وفي معتوق للهجن T1 x L5, T4 x L5 و T4 x L6 وعبر الموقعين هى    (59%)T1 x L2و (45%)T3 Xl2   و (50%)T3 x L6. ومن خلال هذه الدراسة نوصى باستخدام هذه الهجن بعد إجراء بعض الاختبارات الخاصة بالإنتاجية في مواقع ومواسم مختلفة.     &nbsp

Proton-nucleus total reaction cross sections in the optical limit Glauber theory: Subtle dependence on the equation of state of nuclear matter

We calculate the proton-nucleus total reaction cross sections at different energies of incident protons within the optical limit approximation of the Glauber theory. The isospin effect has been taken into account. The nucleon distribution is obtained in the framework of macroscopic nuclear models in a way depending on the equation of state of uniform nuclear matter near the saturation density. We find that at an energy of order 40 MeV, the reaction cross section calculated for neutron- rich isotopes significantly increases as the parameter L characterizing the density dependence of the symmetry energy increases, while at energies of order 300 and 800 MeV, it is almost independent of L. This is a feature of the optical limit Glauber theory in which an exponential dependence of the reaction cross section on the neutron skin thickness remains when the total proton-neutron cross section is small enough.Comment: 5 pages, 4 figure