120082165
g-Boson renormalization effects in the interacting Boson model for nondegenerate orbits
Abstract A nonperturbative model-space truncation procedure is utilized to include the effects of a single g boson on the parameters of the neutron-proton Interacting Boson Model in the realistic case of nondegenerate single-particle orbits. Particular emphasis is given to the single-boson energies ϵd ϱ ( ϱ = v , π ), with numerical results presented for the even isotopes of Hg. Only part of the observed renormalization is obtained. Possible sources of further renormalizations to ϵd ϱ are discussed. Results are also presented for the renormalizations of the boson quadrupole parameters κ and χ ϱ .
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.
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.
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.
17624710
The Level-0 muon trigger for the LHCb experiment
The Level-0 Muon Trigger looks for straight tracks crossing the five muon stations of the LHCb muon detector and measures their transverse momentum. The tracking uses a road algorithm relying on the projectivity of the muon detector. The architecture of the Level-0 muon trigger is pipeline and massively parallel. Receiving 130 GBytes/s of input data, it reconstructs muon candidates for each bunch crossing (25 ns) in less than 1.2 μs. It relies on an intensive use of high speed multigigabit serial links where high speed serializers/deserializers are embedded in Field Programmable Gate Arrays (FPGAs).
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. >
139625693
The Data Acquisition System of the Liquid Argon Calorimeter Testbeams 1996
123497982
Software engineering techniques and CASE tools in RD13
Abstract The RD13 project was approved in April 1991 for the development of a scalable data-taking system suitable for hosting various LHC studies. One of its goals is the exploitation of software engineering techniques, in order to indicate their overall suitability for data acquisition (DAQ), software design and implementation. This paper describes how such techniques have been applied to the development of components of the RD13 DAQ used in test-beam runs at CERN. We describe our experience with the Artifex CASE tool and its associated methodology. The issues raised when code generated by a CASE tool has to be integrated into an existing environment are also discussed.
125160328
A realistic algorithm for the level 0 muon trigger