VLAD for epithermal neutron scattering experiments at large energy transfers

Abstract

Abstract. The Very Low Angle Detector (VLAD) bank will extend the kinematical region covered by today's epithermal neutron scattering experiments to low momentum transfer (< 10 Å -1 ) together with large energy transfer > 1 eV. Such kinematical region is so far unexplored and will allow for new experimental studies in condensed matter systems. VLAD is at present being commissioned on the VESUVIO spectrometer at the ISIS pulsed neutron source. It consists of an array of Resonant Detectors covering the scattering range 1°-4°. In this paper the design of VLAD is presented together with Montecarlo simulations of the detector performances. The results of tests made with prototype VLAD detectors are also presented, confirming the usefulness of the Resonance Detector for measurements at very low scattering angles.

Radiative neutron capture as a counting technique at pulsed spallation neutron sources: a review of current progress

“…As far as epithermal neutron scattering is concerned, since 1986 an extensive research and development activity was carried out at ISIS originally on the eVS and subsequently on the VESUVIO spectrometers [9,10,31,[49][50][51][52][53][54][55][56][57][58][59][60][61][62][63][64][65][66]. Part of this research activity was addressed to develop and enhance the capabilities and effectiveness of the so-called resonance detector spectrometer (RDS) configuration, conceived and tested in the early 1980s [67][68][69][70][71][72][73].…”

Advances on detectors for low-angle scattering of epithermal neutrons

“…This translates into the need for detecting neutrons of tens of eV at scattering angles between 1 • and 5 • . Accordingly, the spectrometer has been modified by narrowing the neutron beam collimation and by fitting a new vacuum vessel, providing minimum attenuation of the neutrons scattered at low angles [6]. These are detected in the VLAD detector bank which is based on the resonant detector (RD) technique [7].…”

“…The VLAD detector bank is shown schematically in figure 1 and a detailed description of the technical aspects of the detector mechanics is given in [6]. A total of 20 detector units, divided into five rings for optimal light collection and spatial resolution, cover the angular range 1 • -3 • at a distance The need to pack a number of detector units into a small volume poses some design issues.…”