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Bicron Szintillation Detector Setup Guide


CMC

July, 2005

 

 

 

Setup:

 

  1. Before assembling the detector system, make sure that the high voltage is turned off.

 

  1. Connect the detector low power cable (DB-9) to the low voltage power supply.  (See Setup Diagram (.pdf), Purple line)

 

  1. Connect the detector high voltage cable to the positive high voltage supply.  (See Setup Diagram (.pdf), Red line)

 

  1. Connect the detector output cable to the input of the spectroscopy amplifier for positive signals.  (See Setup Diagram (.pdf), Green line)

 

  1. Connect the output of the spectroscopy amplifier to Channel 1 on the oscilloscope.  (See Setup Diagram (.pdf), Orange line)

 

  1. Connect output of spectroscopy amplifier to input of the ADC/Multi-channel Analyzer (optional).  (See Setup Diagram (.pdf), Orange line)

 

  1. Connect 3 SCA outputs on the back of the spectroscopy amplifier to 3 inputs of NIM→TTL Converter.  Be sure to use the top half of the channels (for NIM→TTL conversion).  (See Setup Diagram (.pdf), Black lines)

 

  1. Connect NIM→TTL converter outputs to inputs of VME Scalar.  (See Setup Diagram (.pdf), Brown lines)

   

 

Initial Spectroscopy Amplifier Settings:

 

  1. Set “Mode” to “Gauss”

 

  1. Set “Shaping Time” to “.12 µs” (for high count rate operation)

 

  1. Set approximate “Course Gain” and “Fine Gain” according to table below:

*Note: Total Gain = Coarse Gain x Fine Gain

 

 

Gain Settings and Approximate Amplifier Outputs for

Various Incident Energies

(Measured with Am-241 radioactive source)

 

Energy

[keV]

Gain

[Coarse/Fine]

Output

[V]

22.16 (Ag)

50/0.6

2.15

17.48 (Mo)

50/0.8

2.3

13.40 (Rb)

50/1.0

2.2

8.05 (Cu)

50/1.4

1.8

Operation:

 

  1. Turn High Voltage on to 650V.  *Note: Green display on HV Power Supply will read 0.65 kV.

 

  1. With x-rays or radioactive source present, the oscilloscope trace should look something like this:  

Oscilloscope Trace

 

 

  1. Adjust gain on spectroscopy amplifier so that the signal of interest has an amplitude of between 2 and 3 V.

 

 

 

Setting of SCA Windows:

 

  1. In main EPICS menu, open [ Canberra B] > [ICB TCA 1].

 

Canberra B menu in main EPICS menu

 

 

  1. The ICB TCA window should open at this point (See photo below).  If ICB TCA window displays “Can’t Communicate,” switch “Output Polarity” from “ Normal ” to “Inverted” and back to “ Normal .”  “Can’t Communicate” message should disappear; if not, call beamline staff for assistance.

 

ICB TCA window

 

  1. In main EPICS menu, open MCA window by selecting [ Canberra B] > [MCA 1 Display].

 

                                                                                                                     

  1. With x-rays or radioactive source present, click “Erase&Start” in MCA window to accumulate a spectrum.

 

  1. With x-rays or radioactive source present, the spectrum should feature one or more Gaussian-like peaks as seen below:

 

Spectrum for Rubidium (Rb)

(Collected with Am-241 radioactive source)

   
   
  1. Determine channel numbers of regions of interest and convert to SCA percentages, considering that 2048 channels correspond to 100%.  (See Diagram at right.)

 

  1. In ICB TCA window, set SCA regions accordingly.  (See Diagram at right.) 

 

*This concludes the setting of the SCA windows.

 

 

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