Parallel computing in information retrieval - An updated review

The progress of parallel computing in Information Retrieval (IR) is reviewed. In particular we stress the importance of the motivation in using parallel computing for Text Retrieval. We analyse parallel IR systems using a classification due to Rasmussen [1] and describe some parallel IR systems. We give a description of the retrieval models used in parallel Information Processing.. We describe areas of research which we believe are needed

The neutron spectrum of plutonium fluoride

The neutron spectrum of PuF<SUB>4</SUB> has been theoretically calculated using the measured total <SUP>19</SUP>F(α, n)<SUP>22</SUP>Na cross sections, and compared with available experimental data. There is good agreement with regard to the main peak as well as the maximum energy of the spectrum. The calculated spectrum explains all the features of the observed spectrum

Calculations of responses to representative neutron spectra of albedo neutron dosemeters incorporating LiF thermoluminescent detectors

The responses to representative neutron spectra from the Health Physics Research Reactor in the USA of some albedo dosemeter configurations using commercially available LiF TLD chips have been calculated, and methods suggested for correcting the energy response of albedo dosemeters

Sodium pyrophosphate- a new thermoluminescent detector

Sodium pyrophosphate doped with dysprosium oxide in the ratio of 1000 : 1 by weight has been developed as a thermoluminescent detector. The gamma ray response characteristics of the prepared phosphor along with the thermal and fast neutron responses are reported in this paper. The phosphor has an emission spectrum consisting of two peaks at 480 nm and 580 nm. It has three glow peaks at 90°C, 181°C and 228°C. The low temperature peak decays rapidly on storage and the glow peak at 181°C is stable and useful for dosimetry purposes. The integrated thermoluminescence has always been measured three days after irradiation. The trap depths for the three glow peaks have been determined as 0.89 eV, 1.24 eV and 1.58 eV respectively. The optimum annealing temperature of the phosphor is found to be 400°C. The photon energy response of the new phosphor was estimated theoretically and experimentally and found to be similar to that of LiF (TLD-100). The exposure range covered was from 0.41 C·kg−1 to 3.30 C·kg−1 of 60Co gamma radiation and the TL output is found to be linear in this range. The response of the phosphor per unit thermal neutron fluence is equivalent to 1.3 × 10−14 C·kg−1 of 60Co gamma radiation. The kerma in sodium pyrophosphate for various neutron energies were computed. A fast neutron exposure of 10 mSv gives a TL output equivalent to 1.95×10−6 C·kg−1 of 60Co gamma rays