RoboLab+Exercise+-+HPGe+γ-spectroscopy+of+environmental+samples

If you wish to use GammaLab, you will need to book a timeslot with the University of Hannover. You also need to download the following plug-ins: [|ni.com/download/labview-run-time-engine-2016/6069/en/] []

Once you have downloaded the plug-ins and confirmed your timeslot, please click on the link below to access the GammaLab. [|GammaLab]

__**GammaLab**__

In GammaLab a user can choose a selection of samples and measure them with an HP-Ge-detector. Samples range from ordinary drinking water to soil samples from nuclear hazard sites as well as calibration standards.

Outcome:

– Practical experience in gamma-spectrometry of different real samples and learning the importance and use of calibration standards. – Identification of the different radionuclides and determination of their activity. – Meaning and importance of characteristical limits in the evaluation of environmental samples.

The setup is presented in Fig.1.



Fig.1. GammaLab setup

On top you will see the different control tabs: “Sample selection”, “Detector operation”, “Log” and “Help”. The first tab, “Sample selection”, allows you to select between 6 different samples: a calibration one and 5 unknown ones. You can select the desired sample from the drop-down menu, and validate your choice by pressing “Put selection in detector”. You can close the shielding of the detector by clicking on the “Open/close Shielding” button. You can always check the status of the experiment in the window under the “Open/close shielding” button. During each movement of the robot are all buttons greyed out, so you cannot give two commands at a time.

You can quit the experiment by pressing on the bottom left the "Log out and exit" button.

In the “Detector operation” tab you introduce the measurement time (default 600s) and you can start and stop the measurement of the sample with the HPGe- detector. The spectrum is building up in real time in the window on the right. After you have finished measuring your sample, you can send the results to your email address. You will receive a text file, which contains information regarding the sample you measured, the status of the shielding and the duration of the measurement, followed by the γ-spectrum, given as channel number of counts.



There is a log- tab available, in which all your activity is being recorded. You can also insert your own notes here. You can send the log-file to your email-address.

__//Step 1 – Measurement of the calibration sample//__

Place “Sample 1” (the calibration standard) in the detector. Close the shielding. Switch to the “Detector operation” tab, and measure for 5 minutes. Send the calibration file to your email address.

__//Step 2 – Calibration of the detector//__

Draw the spectrum you have received with a program of your choice (Excel, Origin, Gnuplot, etc). You will see six bigger peaks, one for each energy shown in this table:


 * = Element ||> Energy(keV) ||> Photonemission(1.12.2016) ||
 * = Ba-133 ||> 81 ||> 812 ||
 * = Co-67 ||> 122 ||> 96 ||
 * = Ba-133 ||> 356 ||> 1373 ||
 * = Cs-137 ||> 662 ||> 4184 ||
 * = Mn-54 ||> 835 ||> 197 ||
 * = Zn-65 ||> 1116 ||> 97 ||

The relationship between the amount of energy transferred to the detector and the number of the channel in which this pulse is stored is linear: Energy = a*(channel number)+b

From the plotted spectrum you can attribute to the central channel of each peak the according energy. With these six points you can perform a linear calibration, to find the function that attributes to each channel number the according energy.

 In GamThemaLab a user can choose a selection of samples and measure them with an HP-Ge-detector. Samples range from ordinary drinking water to soil samples from nuclear hazard sites as well as calibration standards. //__Step 3 – Measurement of an unknown sample__//

Put another sample in the detector. The shielding will be opened automatically, the previously measured sample will be placed back on its initial position, and the new sample will be placed in the detector. Don’t forget to close the shielding of the detector. Switch to the “Detector operation" tab and start with a ten minute measurement. Depending on which sample you have chosen, can be ten minutes sufficient or not. It is up to you to determine that. After you will send the spectrum to your email address, plot the count rate against the energy. Determine the energy of the peaks of the new sample, and attribute to the corresponding nuclides. You can repeat this procedure for all other 4 unknown samples.

__//Step 4 – Shutting down GammaLab//__

All you have to do is to press the “Log out and exit”-button. If there is still a sample in the detector, the shielding will automatically open and the sample which is in the detector will be placed back in the rack; the robotic arm will go to its initial position. Close your browser.