GammaVision
®
v7 (A66-BW) 783620H / 1013
If you have software-controlled hardware (as distinguished from NIM units with front- and rearpanel hardware adjustment controls), skip to Section 3.2.9.3.
3.2.9.2. Detectors Set Up Manually
Adjust the spectroscopy amplifier gain, shaping time, and pole zero. This is a manual operation which should be carried out according to the instructions given in the amplifier manual. Most commonly, a range of 0–3 MeV is used. If you have a
60
Co source, the 1332 keV peak should be set at approximately channel 1816 for conversion gain of 4096 and channel 3632 or 7264 for
8192 or 16384, respectively. A source with only one or two lines (e.g.,
137
Cs or
60
Co) should be used for the initial test spectrum so you’ll be able to easily see the correct pattern of the peaks.
3.2.9.3. Computer-Controlled Hardware Setup
In this section, we will use Gamma-
Vision to enable the DSPEC-50's high voltage and adjust the spectroscopy amplifier gain and shaping constants.
Click Acquire/MCB Properties... to open the Properties dialog for this MCB, and click the High
Voltage tab (see Fig. 38). Set the
Target bias. When the value of the detector bias matches that shown on the detector’s Quality
Assurance data sheet (also given on the endcap label), click the
On button and note the Actual
Fig. 38. Monitoring the DSPEC-50 Bias Setting on the
High Voltage Tab.
voltage readout. If the On/Off indicator reads Shutdown, the detector is most likely warm. (The detector might require 3–6 hours after filling before it is cold enough to take bias.)
3.2.9.4. Amplifier Settings
The Amplifier tab (Fig. 39) lets you set the amplifier shaping time to either Long or Short. The
Long shaping time is the recommended choice for low to moderate count rates. The value of the shaping time (in
μs) is given in the hardware manual.
38
