120438846
Microscopic aspects of the IBA
Abstract The current status of efforts to derive the Interacting Boson Model (IBM) from the microscopic Shell Model is described. Although several boson mapping procedures presently exist, only the procedure of Otsuka, Arima and Iachello (OAI) is discussed in detail. The IBM bosons are assumed to be correlated pairs of identical nucleons of definite generalized seniority and angular momentum. The steps, which must be implemented in the OAI procedure in order for it to be considered a truly microscopic theory of the IBM, are then described. Using this procedure, we present results of typical calculations for the IBM-2 parameter X v , as an illustration.
119667576
Interacting boson approximation model of the tungsten isotopes
The interacting boson approximation model of Arima and Iachello and co-workers has been used to make a schematic study of the tungsten isotopes. For each isotope of tungsten we determine the values of the five parameters in the interacting boson approximation Hamiltonian which yield the best fit to the experimental energy spectrum. Based on these values, we can extrapolate to isotopes for which no experimental data exist and can make predictions for future experiments. Using the same values of these parameters for each isotope, we can also obtain the B(E2) transition rates, the rho(E0) values, the quadrupole moments of the first two excited 2/sup +/ states, the two-neutron separation energies, and the isomer and isotope shifts. Where data exist our results, in general, agree very well with experiment, although more experimental information is needed for the isomer and isotope shifts and the quadrupole moments of the excited 2/sup +/ states. The long range goal is to understand the origin of the model parameters in terms of a microscopic theory, such as the nuclear shell model.
120360964
Particle-hole ambiguity in the parameters of the microscopic interacting boson model
The parameters of the microscopic interacting boson model that emerge from a multi-nondegenerate-orbit theory are shown to depend on whether they are generated in terms of correlated pairs of particles or correlated pairs of holes. It is suggested that the ambiguity results from the shell-model truncation inherent in the interacting boson model and that it can be alleviated by including renormalization effects from outside the interacting boson model subspace.
120940069
Shell-model determination of the interacting boson model parameters for two nondegenerate j shells
The interacting boson model is examined from a microscopic viewpoint using the generalized seniority scheme. The present discussion focuses on regions of the periodic table in which the many nondegenerate nucleon orbits can be approximated in terms of two nondegenerate orbits, the sum of whose occupancies is chosen to be the same as the total occupancy of the major shell being studied. Predictions for the interacting boson model parameters are obtained by constructing the zeroth-order boson images of the corresponding fermion operators. Calculations are carried out for the tungsten isotopes, and the predicted interacting boson model parameters are found to be in good overall agreement with the empirically determined values for the tungsten isotopes. The calculations reproduce the observed SU(3) or rotational character of the low-lying energy states in the N = 96 to 114 mass region.
139625693
The Data Acquisition System of the Liquid Argon Calorimeter Testbeams 1996
62769141
H1 CALORIMETER DAQ UPGRADE FOR HERA-II
115276040
Specification of the muon trigger processing board
110847784
A VME RISC processor farm for third level triggering
The need for very fast, compact, VME-based farms of processors exists in many areas of experimental physics. Reported is a development for such a farm targeted at the requirements of the online and trigger system of the CERN experiment PS195 (CPLEAR). The system is characterized as being VME based and requiring small events (around 1 kbyte) to be processed at a high rate (greater than 1 kHz). The development was for a single chassis system, using the MIPS R3000 chip mounted on a commercially available board. >