MainPage:Nuclear:EquipmentOp

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This page constains a brief explanation of one method to flash a LED and measure a PMT signal with the CAMAC ADC of the Nuclear Physics lab at CUA. I (Marco Carmignotto) use this method because it have showed to be very stable and reproductible, but other methods also exist!

Creating trigger for all the modules

This is the first step if you want to work with LED. One need to create a trigger signal that will be split and modulated to flash the LED, create an integration gate for the ADC and send a read command to the computer module.

1) Control the frequency of the trigger - how many pulses per second you want in your system. Take care with limitation of the computer acquisition, I prefer not to exceed 3000 events per second.

2) If needed, you control the pulse shape here. Keep the base of the signal in 0V and create a -1V pulse to send to module Quad Gate Generator.

3) Module Quad Gate Generator receives the main trigger and create secondary pulses to all parts of the electronics. When this module is working, you can see an LED flashing on the side of the input. The main reason it stops working is some wrong levels in the input (check item 2 again).

• NIM output of this module goes to module AVTECH AV-10-30-C (create LED pulse).
• One output goes to channel 1 of module Level Translator (modulate pulse to create read signal in computer)
• Another output for the counting module (monitoring purpose only).
• The delayed output goes to module Quad Four-Fold Logic Unit (to create ADC gate). Control the delay (to match PMT signal inside ADC gate) using a small screwdriver in the width pot.

Pulsing LED

In order to flash a LED, I prefer to use the module AVTECH. It can also be done with module PG502 Pulse Generator, but this last option showed to be more complicated to get reproductibility.

According to the labeled buttons on this module:

4) I generally use this module in external trigger mode.

5) Input signal comes in general from NIM output of module Quad Gate Generator.

6) The pulses I use generally are created with full range amplitude in 15ns. If you need more than that, be carefull to have your PMT signal not exceeding the trigger gate width. If you want to check if an LED is working, pulses of milliseconds can be created, so you can see the LED with eyes.

7) You have a fine adjust the LED pulse width with this pot.

8) The full scale of the amplitude of the pulses is controled here. Remmember to select the right polarity of your connection to the LED.

9) The fine adjust of the LED pulse amplitude is done here.

Creating ADC gate

Make sure your PMT signal is inside ADC gate. I use module Quad Four-Fold Logic Unit to create the gate because it is much more stable than module PG502 Pulse Generator. You can adjust the gate width up to approx. 60ns with this module. Leave 5ns between the gate and the signal (this is the time ADC needs to start integrating).

10) Use the central folds selection to make coincidence, if you want. In the case of using this module only for creating a gate, put this in 1 fold. Control the width of the output using a small screwdriver. If you need to delay or antecipate the gate with respect to the signal, go back to item 3.

ADC

This module integrate the charge of your signal over the time given by the gate. Signal should be negative and not exceed -1V.

11) Connect the gate from the Quad Four-Fold Logic Unit module. 12) Connect PMT signal to one of the input channels.

CODA

This is a very tricky software. Make sure to use it as smooth as possible, because if it breaks downs it is always hard to fix.

• To start a run, click on the forward button.
• To stop a run, click on the stop button.
• To convert a file to a text file, use root2ascii:

./root2ascii coda/test_1234.dat > coda/test_1234.txt

CAEN VME HV Module

Running "sample" code

This code allows one to "easily" control the parameters of any board using the V1718 control module.

To access the module:

 ./CAENVMEDemo V1718 1

To set up V6533N Address Base (according to its switches SW8, 9, 10, 11 located in the very back of the modulus):

 Type 2        - to change "BASE ADDRESS"
 Type 32100000 - considering SW8=3 SW9=2 SW10=1 SW11=0, as it came originally

Turning ON/OFF channel 0:

 Type 1  - to set "ADDRESS"
 Type 90 - Address of PW for channel 0
 Type W  - to write on this register ("R" to read)
 Type 1  - to turn channel 0 ON (0 would turn it OFF)

To set/read HV on channel 0:

 Type 1    - to change "ADDRESS"
 Type 80   - Address of VSET for channel 0
 Type W    - to write on this register ("R" to read)
 Type 10*V em HEX (10 times the voltage you want in HEX format, e.g. if you want 1000V, type 2710 (it means 10000 in HEX))