Determination of the dead-time losses in NaI(Tl) gamma-ray spectrometer

The 12 NaI(Tl)-detector gamma-ray spectrometry system (GSS) “Romashka”[1,2] has recently been equipped with a new computer controlled HVSys 16 channel high-voltage power supply with preselected single channel polarity [3] (Fig.1). In order to do some preliminary checks of the GSS chains’ characteristics, a single channel gamma-spectrometry tract was commissioned. It was consist of a single Romashka’s section NaI(Tl) crystal, optically coupled with a photo-multiplier tube FEU-110, a POLON TM Active Filter Amplifier and an EG&G ORTEC TRUMP TM -2k Multichannel Buffer (MCB) PCcompatible plug-in card, run by Maestro TM MCA Emulation and Analysis Software for Windows®, having real-time and life-time acquisition presets [4]. Two calibration sources method was applied for obtaining the effective dead-time (and dead-time losses) of a single spectrometry chain. It was used, also, to determine the dead-time of the chain when a Parsek LLC desktop 8k multichannel analyzer (MCA) with no live-time measured/indication possibility [5]. The testing of the whole gamma-ray spectrometry system with the new HV power supply has been recently accomplished. It is planned to use the modernized “Romashka” GSS at the JINR FLNP resonance neutron time-of-flight (TOF) spectrometer IREN, for investigation of the gamma-rays emission from neutron inelastic scattering, capture and fission reactions, using the multiplicity method [2].