Alpha Spectroscopy Two pairs of detectors, in a vertical arrangement 1A 2A 1B 2B Vacuum Light Constant illumination indicates the unit is ready to acquire data Fault Light A steady light indicates the unit is ready for communication with the PC Important things to know before you load your samples: The PC for the alpha spectrometer also runs the Tennelec Proportional Counter, both machines may be operated simultaneously by the PC Make sure you or your samples do not contact the detector face during loading and unloading of your samples Move high activity samples further from the detector window to prevent particles from implanting themselves in the detector window Vacuum is pulled on two chambers even if only a single chamber is being used, if you pump down 1A, then 1B will also be under vacuum Once vacuum is pulled on one set of chambers, pulling vacuum on the other chambers may result in a partial loss of vacuum in all chambers. This means that all samples must be loaded at the same time to guarantee a continuous vacuum; the Hold function may be used on the chambers while samples are swapped out and the other units are pumped down, but vacuum may not be maintained by chambers under Hold. After a sample swap
is completed and vacuum restored to the other chambers the chambers under Hold should be placed under Pump again. Samples must be dry, wet samples will result in extremely long pump down times as the vacuum pump tries to pull vapor from chamber. Before Starting the Alpha Acquisition software 1. Turn on Alpha Spectrometer (switch on back by power cord) 2. Check oil level on vacuum pump. If the oil level is midway between Min and Max, switch on the pump. The switch is located on the right backside of pump. (If the oil level is just above Min, put more oil in the pump ) Initialization of spectrometer with PC may take a few minutes. If initialization fails, close software and try reopening the Alpha Acquisition software again (LED Fault Light on the front of the spectrometer should not be flashing). Alpha Acquisition & Analysis.lnk Sample Loading 1. Open chamber door, if the chamber door won t open the chamber may still be under vacuum. DO NOT PRY DOOR OPEN. To release vacuum, make sure the detector is open via the acquisition software (File -> Open Datasource -> Detector -> select detector -> Open), make sure the detector window is open, then go to MCA, select Adust, select Vac, then Vent and Exit. In a second or two the spectrometer should make a hissing sound and the door can be opened. 2. Load samples, noting the sample holder position in the chamber. High activity samples should not be placed directly under the detector window (move them down a few steps) 3. Before closing door, make sure the door seal is clean. Any dirt on the door seal will result in a vacuum leak Operation 1. Open Alpha Acquisition software Alpha Acquisition & Analysis.lnk
2. Open Detectors (File->Open Datasource -> Detector -> select detector -> Open) 3. Load samples 4. Make sure vacuum pump is on 5. To pull vacuum on 1A or 1B select either 1A or 1B, for 2A or 2B select either 2A or 2B then go to MCA -> Adjust -> Vac -> Pump -> Exit, in a few seconds the chamber will begin to pump down
6. Pumping times may vary between 2 to 10 minutes, if pumping time takes longer than 10 minutes check the door seals for leakage (shut down the pump, vent the chamber and wipe the door seal with a clean kim wipe). 7. To check the status of the detector go to MCA -> Status 8. The following screen will appear, to exit this screen click OK, to monitor the vacuum pumps progress click Update
9. The chamber is ready for data acquisition when the yellow Vacuum light on the spectrometer (between the doors or each detector pair) stops flashing 10. Press the Start button on the spectral window to begin counting the sample, to count on multiple detectors each detector must be started separately through its own spectral window 11. Leave pump running while samples are being counted 12. To stop a detector, go to its spectral window and press the Stop button. Each detector must be stopped through its own spectral window Saving Data Saving your data immediately after stopping your counting is highly recommended, bad things will happen if communications are lost with the spectrometer before your data file is saved. Data can be stored in two file formats *.cam files and *.iec files. Cam files are proprietary files that can only be handled by the Genie software. IEC files can be handled by Excel and a Macro has been written to convert both Alpha and Gamma files to an easily exportable file type. As long as data is saved as a *.cam file it can be converted to an *.iec file at a later date.
Unloading Samples 1. Release chambers from vacuum by selecting MCA -> Adjust -> Vac -> Vent -> Exit. In a second or two the chamber will make a hissing sound and the door may be opened. 2. Remove samples