Mutual heavy ion dissociation in peripheral collisions at ultrarelativistic energies

We study mutual dissociation of heavy nuclei in peripheral collisions at ultrarelativistic energies. Earlier this process was proposed for beam luminosity monitoring via simultaneous registration of forward and backward neutrons in zero degree calorimeters at Relativistic Heavy Ion Collider. Electromagnetic dissociation of heavy ions is considered in the framework of the Weizsacker-Williams method and simulated by the RELDIS code. Photoneutron cross sections measured in different experiments and calculated by the GNASH code are used as input for the calculations of dissociation cross sections. The difference in results obtained with different inputs provides a realistic estimation for the systematic uncertainty of the luminosity monitoring method. Contribution to simultaneous neutron emission due to grazing nuclear interactions is calculated within the abrasion model. Good description of CERN SPS experimental data on Au and Pb dissociation gives confidence in predictive power of the model for AuAu and PbPb collisions at RHIC and LHC.Comment: 46 pages with 7 tables and 13 figures, numerical integration accuracy improved, next-to-leading-order corrections include

Cargo Cults in Information Systems Development: a Definition and an Analytical Framework

Organizations today adopt agile information systems development methods (ISDM), but many do not succeed with the adoption process and in achieving desired results. Systems developers sometimes fail in efficient use of ISDM, often due to a lack of understanding the fundamental intentions of the chosen method. In many cases organizations simply imitate the behavior of others without really understanding why. This conceptual paper defines this phenomenon as an ISDM cargo cult behavior and proposes an analytical framework to identify such situations. The concept of cargo cults originally comes from the field of social anthropology and has been used to explain irrational, ritualistic imitation of certain behavior. By defining and introducing the concept in the field of information systems development we provide a diagnostic tool to better understand one of the reasons why ISDM adoption sometimes fail

Two-phonon giant resonances in sup 1 sup 3 sup 6 Xe, sup 2 sup 0 sup 8 Pb, and sup 2 sup 3 sup 8 U

The excitation of the double-phonon giant dipole resonance was observed in heavy projectile nuclei impinging on targets of high nuclear charge with energies of 500-700 MeV/nucleon. New experimental data are presented for sup 1 sup 3 sup 6 Xe and sup 2 sup 3 sup 8 U together with further analysis of earlier data on sup 2 sup 0 sup 8 Pb. Differential cross sections d sigma/dE sup * and d sigma/d theta for electromagnetic excitations were deduced. Depending on the isotope, cross sections appear to be enhanced in comparison to those expected from a purely harmonic nuclear dipole response. The cumulative effect of excitations of two-phonon states composed of one dipole and one quadrupole phonon, of predicted anharmoniticies in the double-phonon dipole response, and of damping of the dipole resonance during the collision may account for the discrepancy. In addition, decay properties of two-phonon resonances were studied and compared to that of a statistical decay