Paula (Programmable AUtodepositionLAb)
The AutodepositionLab gives the user the opportunity to choose from a selection of metals and immerge them into a solution containing a radioactive electrolyte followed by Geiger-detection of the activity deposited on it’s surface.
Outcome:
– Practical experience in Geiger-detection and its potential as well as limitations for the detection of weakly penetrating radiation.
– Introduction of the approach of producing thin-layered solid samples for a reliable detection.
– Teaching the basics of electrochemistry by using metals of different nobility.
Programmable AutodepositionLab
You are going to use the RoboLab in this exercise.
Remember that you are actually performing a real experiment. Thus, only one student can access the remote controlled laboratory at any time. Please do not interrupt an ongoing experiment. If you want to, you can use one of the computers in the counting room at the course lab. The RoboLab is running under LabView version 8.2 and you need the corresponding LabView plug-in. Refer to the RoboLab introduction (available via Fronter) to avoid problems during the installation and log-on procedure.
The setup is presented in Figure 1.
The interface is divided in two parts. You can control the robot using the buttons on the left side, and the camera feed on shows the movements of the robot on the right side.
The first tab, “Sample selection”, has six different buttons:
The “Get sample” button lets you select the desired metal plate (copper or steel) and the magnetic arm will grab the chosen metal sheet.
The “Put sample in solution” button lets you select the time you want to immerse the metal plate into the solution containing the radioactive electrolyte, and by pressing the button it will lower the metal plate into the solution. After the selected time will pass, the magnetic arm will automatically lift the metal plate from the solution.
The “Clean sample” button will rinse the metal sheet for the time that you have written in the field next to it (be default 15 s).
The “Bring sample to detector”-button moves the metal sheet in front of the Geiger-Müller counter. After you have finished the experiment, and want to dispose of the used metal sheet, press “Put sample in waste container”.
The “Detector+Log” tab permits to set the measurement time for which the Geiger-Müller will measure the metal sheet (the default time is 300s). The “Start counting”-button starts the measurement, and you can stop the ongoing measurement anytime by pressing “Stop counting”.
The “Log” tab records every action you have performed since the start of the experiment (chose sample, time of immersion, measurements, etc). You can also record your own notes, if you want. You can retrieve this file via mail.
You can quit the experiment by pressing on the bottom left the "Logout and Exit" button.
Step 1 – Select the sample
Choose from the dropdown menu at the right of the “Get sample”-button the iron sample and press the “Get sample”-button to retrieve it from the sample rack.
Step 2 – Blank measurement
Move the sample in front of the Geiger-Müller detector by pressing “Bring sample to detector”. Switch to the “Detector+Log” tab and perform a measurement of the metal plate.
Step 3 - Autodeposition
Switch back to the “Sample selection”-tab, choose the time you want to immerse the metal plate into the radioactive solution and press the “Put sample in solution”-button.
Step 4 – Cleaning
Move the metal plate to the cleaning station by pressing the “Clean sample”-button. Wait 10 to 15 minutes for the sample to dry.
Step 5 – Measurement
Move the sample in front of the Geiger-Müller detector by pressing “Bring sample to detector”. Switch to the “Detector+Log” tab and perform a measurement. Did the value change, compared to the one obtained at step 2? Why? (If you didn’t write down the obtained value, you will find it on the right side of the “Detector+Log”-tab)
Step 6 - Repeat
Redo step 3-5 a few times. After a while you will observe that the counts you obtain from the measurements start to be constant. Why?
Step 7 – Waste
Press the “Put sample in waste container” – button, to dispose of the used metal sheet.
Step 8 – Repeat with copper
Repeat step 1-5 with the copper plate. Is there a difference between the blank measurement and the measurement after the autodeposition process? Why?
Step 9 – Shutting down AutodepositionLab
After you have finished with your last measurement, move the metal plate to the waste bin, by pressing the “Put sample in waste container”-button. Then press the “Logout and exit”-button. Close your browser.