DSPEC 50
®
and DSPEC 502
®
Digital Gamma-Ray Spectrometer User’s Manual
932502G / 0618
the total counts in each of the peaks is correct. For a detailed discussion, see Section 1.6.
!
Low-Frequency Rejector (LFR)
When ON, removes low-frequency (<3 kHz) input
noise from spectrum., as discussed in Section 1.5.
!
Resolution Enhancer
Correct for charge trapping by “training” the spectrometer to
accommodate the particular performance of your detector; see the discussion in
Section 1.3.
!
Enhanced Throughput Mode
Protection time range from 0.1 ìs to 200 ìs in 25 ns
increments. See Section 1.4.
LFR Mode
Highest Throughput
(minimum Protection Time)
Lowest Throughput
(maximum Protection Time)
Off
(Rise Time + flattop)
(2 × Rise Time + Flattop)
On
(3 × Rise Time + 2 × Flattop)
(6 × Rise Time + 3 × Flattop)
!
List Mode
In this mode, each detectable event that would normally be histogrammed as
a spectrum is sent to the computer in the form of a pulse-height value along with a time
stamp that indicates the time the pulse arrived. The data can be analyzed by the computer
in real time to determine if some significant event has occurred, or can be streamed to
disk for analysis at a later time. See Appendix E.
Linearity
!
Integral Nonlinearity
<±0.025% over top 99.5% of spectrum.
!
Differential Nonlinearity
<±1% over top 99% of range.
Digital Spectrum Stabilizer
!
Stabilization
Peak centroid (zero and gain) channel 2 to 16384 (65536 for Advanced
models); stabilization window width (zero and gain) ±1 to ±256 channels.
!
Zero Correction Resolution
±64 channels with a minimum adjustment of 0.1 channel
out of 16384 total channels.
!
Gain Correction Resolution
0.00025% (from 99.5% to 100.5% in 4096 steps).
System Temperature Coefficient
!
Gain
<50 ppm/
E
C (typically <30 ppm/
E
C).
!
Offset
<5 ppm/
E
C, with rise and fall times of 12 ìs and flattop of 0.8 ìs (similar to
analog 6 ìs shaping).
68
