N. Chaudhuri

Atomic Rayleigh scattering of phonons in the vicinity of K-absorption edges

New measurements of coherent (Rayleigh) scattering of photons of energies in the vicinity of K-absorption edges of gold and lead atoms together with other recent measurements with a coverage in the momentum transfer region up to 1.0 mc are presented for a critical evaluation of (i) the latest relativistic calculation of coherent scattering factors, (ii) the anomalous dispersion correction to the scattering factors and (iii) the exact numerical Rayleigh scattering amplitudes of inner electron shells. This evaluation reveals the ranges of applicability of these calculations and indicates the trend of behaviour due to the proximity of K-absorption edges of scatter atoms.

A simple ADC unit for cosmic ray air shower experiments

Abstract The design of a new low cost analog-to-digital converter system is described. It is based upon the method of linearising the charging process of a storage condenser and is controlled by logic gates. Its tested characteristics have been found to be reliable for application in cosmic ray air shower experiments.

New measurements of coherent and incoherent atomic scattering factors using radioactive gamma ray sources

Abstract A representative sample of results of our measurements over the photon energy range 0.08–2.00 MeV on coherent and incoherent scattering is presented and compared with theoretical predictions resulting from new calculations at photon energies below and above the K-shell binding energy of heavy atoms. The present results taken with some other recent measurements near and far from K-absorption edges of the scatterer atom help identify the region in photon energy and momentum transfer for the applicability of various theoretical predictions for photon coherent scattering. The Hartree-Fock model for bound electron incoherent scattering is found to be adequate in explaining the measured whole atom incoherent scattering factors over the whole momentum transfer range investigated.

A sample-hold and analog multiplexer for multidetector systems☆

Abstract A new sample-hold circuit with an analog multiplexer system is described. Designed for multichannel acquisition of data from an air shower array, the system is being used for accurate measurements of pulse heights from 16 channels by the use of a single ADC.

A simple method of studying atomic screening effects in pair production

Abstract The development of a simple method for an atomic pair production experiment is described. The preliminary results obtained by removing various experimental difficulties and errors are presented to justify the suitability of the method over other more expensive pair detection systems reported in recent literature.