Patent ID: 6609075
Filing Date: 2003-08-19
Classification: G01T

Abstract:
A method for determining baselines in a spectrometer that measures the energy of events occurring in a detector connected to a preamplifier wherein the preamplifier produces pulses, referred to as event pulses, in response to events, the method comprising:using a first linear filter, referred to as the energy filter and characterized by an energy filter basewidth &tgr;E, to transform event pulses into shaped pulses whose basewidths are nominally equal to &tgr;E; measuring at least some of these shaped pulses to obtain characteristic values as estimates of the energies of the events associated with the shaped pulses, so measured; using an energy filter baseline value to compensate the characteristic values for the fact that the output of the energy filter is non-zero in the absence of event pulses; using a second linear filter, referred to as the baseline filter and characterized by a baseline filter basewidth &tgr;B that is shorter than &tgr;E, to transform event pulses into shaped pulses whose basewidths are nominally equal to &tgr;B; determining times when the output of the baseline filter is at its baseline value; during such determined times, capturing baseline values from the baseline filter; and updating the energy filter baseline value using at least some of the baseline values captured from the baseline filter.