ORTEC 473 - Timing with Other Detectors; Fig. 6.10. the Effect of 473 Threshold Setting on the Apparent Efficiency of Different Ge(Li) Detectors

14
A plot of the percent loss of 511-keV peak counts from for the SRT mode, compared to the CF mode, is shown In Fig.
6.10 as a function of the 473 threshold and the detector size.
6.4. TIMING WITH OTHER DETECTORS
The 173 can also be used to provide timing information from other detectors such as ORTEC surface barrier detectors and
I v-cneigy photon detectors. In general, when the 454 Timing Filter Amplifier is used, the Ge(Li) or Ext mode on the 473 will
pr: 'de ti ie best timing resolution. The Scint mode or the Nal mode will give the best timing resolution for signals with
risetimes in the low nanosecond range.
ORTEC conducts a continuing program aimed at improving timing resolution. Please contact an ORTEC representative for
information concerning your special requirements.
Table 6.1. Timing Resolution for Various Sizes of Ge(Li) Coaxial Detectors
Using ^^Na and the System of Fig. 6.7.
Detector
Dynamic
Range
CF Mode
SRT Mode
FWHM
(ns)
FW(1/10IM
(ns)
FWHM
(ns)
FW(1/10)M
(ns)
FW(1/100)M
(ns)
8.6%
52.6 cc
1,1 :1
4.4 10.1 4.3
10.1 21.6
10:1 4.2 13.6
4.2 10.5
23.4
20:1
4.7
13.5
4.7
12.8
30.4
12.5%
1.1:1 5.0
10.0
5.0 9.5 17.6
10:1
4.5
13.2 4.4 9.4 17.8
62.3 cc
20:1
5.1 14.3
5.0 12.0
24.8
19.6%
1.1:1
7.9 16.4 8.1
16.0
27.3
10:1
8.4 24.0 7.9
17.0
30.0
103 cc
20:1
8.4
26.0
8.4
23.0 40.0
100
DO
- 40
20
19.6%, 103 cc
12.6%, 62.3 cc
8.6%, 52.6 cc
200 400
473 Threshold Setting (keV)
8136
600
Fig. 6.10. The Effect of 473 Threshold Setting
on the Apparent Efficiency of Different Ge(Li) Detectors.