MainPage:Nuclear:NPS:PWO:LightYield

⇐ Back to Neutral Particle Spectrometer

⇐ Back to the Main_Page

Instructions to scan LY

(THIS IS A PRELIMINARY VERSION ONLY)

1. Set the freezer temperature (controller fixed on the wall, on the side of the freezer):
   1. Hold the button SET for 3 seconds
   2. Change the temperature by pressing up/down buttons
   3. Hold the button SET for 3 seconds to save the new temperature
   4. Wait more than 5 hours (?) to stabilize temperature (keep HV on at all time to stabilize PMT also)
   5. Keep one terminal always logging the temperature in the Control computer:
      cd thermometer
      ./MlogT
   6. Check temperature at Control computer:
      cd thermometer
      ./MplotT
      (Ctrl+c to stop the script)
2. Prepare electronics:
   1. On the NIM module N1470, turn on the trigger (ch0) and the signal (ch2) HV. It is set to keep -760V (trigger PMT) and -2300V (signal PMT), draining approximately 670 and 1035 uA respectively.
   2. If gate width change is required, look in the scope the width of the gate. You change it by turning the hidden screw "width" in the NIM module 794, on the 2nd channel.
   3. Make sure the trigger and the signal cables are connected to the ADC.
3. Prepare CODA (DAQ computer):
   1. Options -> Limits -> Set Time Limit
   2. Set the time of each run, i.e., the time each step along the crystal where LY will be measured.
4. Run motor to scan (CONTROL computer) and start CODA when prompted (DAQ):
   1. In a terminal, go to directory motor. Execute the command:
      ./scan_12cm_step1cm_90min (or equivalent for the test you want - be consistent with the time set in CODA!)
   2. If requested, type the password.
   3. Make sure you hear the motor moving
   4. When the terminal prompts that the scan will start in 10 seconds, switch to the DAQ computer and start coda USING:
      Option -> Enable Auto Mode
5. Converting data
   1. In a terminal at DAQ computer, convert the files created:
      ./convertRange.sh 2000 2010
      (Enter password when prompted to transfer data to Control computer)
   2. In a terminal at Control computer, unzip the transferred file:
      cd data
      unzip 2000.zip
   3. Convert the data to ROOT:
      ./convertRangeHex.sh 2000 2010
      
6. Analyze data (important to keep consistency, so we can inter-compare crystals):
   1. Fit the peaks with root (supposing you used the ADC channel 1, otherwise adjust):

root -l 2000.root T->Draw("ch1>>(1201,0,1200)"); [...] (I am going to write a script to do that automatically) - by Marco C.

Light Yield Analysis Instructions (by Salina)

• How to actually take light yield data

1. Wait for freezer to cool at least 4 hours after taking a crystal out/before putting another one in, and BEFORE OPENING THE FREEZER, TURN OFF THE HIGH VOLTAGE OR PMT WILL BE DAMAGED
2. To turn off the high voltage: turn channel 0 to the middle and wait for it to get to 0, then turn channel 2 to the middle at the same time. When it gets down to 0, you can turn both channel 2 and 0 another notch down.

• Putting the crystal in the freezer

1. need to wrap crystal (white 3 layers teflon and then 2 layers black tape on top) with one end covered with white tape and black tape on top.
2. Greece open end of crystal and put crystal inside the holder in the freezer, making sure it is aligned with the source and the PMT. Close the freezer.
3. Check the oscilloscope if the signal is inside the gate: Plug the gate into channel 1 on oscilloscope, and plug channel 1 into channel 3 on the oscilloscope.
4. After you check the oscilloscope and make sure the signal is ok, it is time to take the data.
5. If measuring as a function of position: the script on computer screen which doesn't have coda running (i.e. step in 1 mm in 20 hours) and switch to the screen with coda and you can click start AS SOON AS THE SCRIPT TELLS YOU YOU HAVE 10 SECONDS TO START COLLECTING.

*#* You should make sure if you are measuring as a function of position (with the motor involved), then you should set the time limit on coda; for measurement of just light yield then you should set a time limit through coda for 100K events *# Voila! The data should start collecting, and you can come back to check on it the next day.

• How to analyze the Light Yield data from our DAQ (Data Acquisition) setup

1. Save the data by converting the file in the terminal of the DAQ computer: ./convert <run number> (this is saved in a <runnumber>.txt file in the home directory. And then use: emacs <blah> to see the data. Do this to check if there is anything in the file, because if it is empty, something went wrong.
2. Send the .txt file to your computer and make sure you have the HEX2root.C script (ask Marco or Me)