DSPEC 50
®
and DSPEC 502
®
Digital Gamma-Ray Spectrometer User’s Manual
932502G / 0618
tion. The DSPEC 502 screens are labeled
MCA-1
and
MCA-2
so you can easily tell which
input is onscreen.
!
ORTEC’s formidable suite of enhancements to help achieve optimum system perform-
ance, include Ballistic Deficit Correction, Charge Trapping Correction, the Low-
Frequency Rejector, the data Throughput Enhancer, ZDT™ Mode zero-dead-time count-
ing, and List Mode. These are discussed in detail in the remainder of this chapter.
ORTEC C
ONNECTIONS
software supports an essentially unlimited number of Ethernet or USB
connected DSPEC 50s. In addition, almost any combination of other ORTEC multichannel
buffers
1
(connecting via Ethernet, USB, printer port, Dual-Port Memory Interface, etc.) can be
connected to the same system.
1.1. DSPEC-Family Technologies for HPGe Systems
Resolution Enhancer
In ORTEC DSPEC products, the flattop width parameter of the trape-
zoidal filter automatically corrects for ballistic deficit (Section 1.2). Unfortunately, this doesn’t
compensate for resolution loss due to charge trapping, which results in variations in charge col-
lection efficiency over the crystal volume. The DSPEC 50 uses our Resolution Enhancer, which
enables you to correct for charge trapping by “training” the spectrometer to accommodate the
particular performance of your detector. See Section 1.3.
Enhanced Throughput Mode
This signal processing method allows the spectrometer to begin
sampling the next pulse before the preceding one has returned to baseline. The effect is optimum
throughput while maintaining resolution and peak shape. See Section 1.4.
Low-Frequency Rejector (LFR) Filter
Our Low-Frequency Rejector
2
digital filter surpasses
all signal processing methods for reducing the effects of microphonics, ground loops, and vir-
tually all other sources of periodic noise for HPGe and NaI(Tl) spectrometry. See Section 1.5.
Zero Dead-Time Correction
3
The DSPEC 50 features our innovative ZDT™ mode of opera-
tion, an alternative to the classical “extended-live-time clock.” The ZDT method produces accu-
rate results in
all
situations and completely overcomes some of the shortcomings of extended
live-time methods. Moreover, the new ZDT method overcomes some limitations in previous
“loss-free” dead-time correction methods. Most notably, the ZDT mode does not require any
1
We use the term “multichannel buffer” (MCB) to indicate a multichannel analyzer (MCA) with enhanced
features and data memory.
2
Patent pending.
3
Patent number 6,327,549.
2
