GADDS Instructions updated 1/2014 1. Log onto the Coral computer and enable the Bruker GADDS instrument. There is no password on the Coral computer. Once the instrument is enabled, the screen to the GADDS computer will turn on. 2 . Turn on the GADDS power switch. (green button on the front-right corner of the machine) Wait until the yellow “busy” light stops flashing. 3. Turn on the X-rays. (The x-ray generator is on the lower left front of the instrument.) First turn on the warming current (center button). Then turn on the x-rays (right button). The x-rays will come on at 20 kV and 5 mA; the yellow warning light indicating “x-rays on” will also come on. (If there is an error message on the generator panel, ignore it and try to turn on the generator. If the message persists and the generator will not come on, find Maura). 4. Turn on the AC power switch to the detector bias control panel. The detector bias know should be “on” to collect data, or “off” to move the detector position. To check the detector position, make sure that the detector bias switch is turned off. The normal distance is 6.0 cm; the position in the middle of the track is 15.0 cm. To move the detector, loosen the 2 knobs located on the far side of the mount. Move the detector further back along the rail. Remove the pin from the hole it was in (it is always in the hole with the arrow pointing to the distance that you want.) Place the set pin for the new distance and slide the detector forward until it is hitting the pin. Tighten the knobs. Switch the detector bias switch to the on position. 5. Mount the sample on one of the GADDS holders. If access to the sample holder is restricted because of the detector angle, drive the detector (2theta) and sample holder (omega) to 0 deg (see below). There are separate instructions for using the full wafer sample holder. 6. Open the GADDS-Manual-Chi-Video program which is on the desktop. Under the Project menu, switch to your project (which will be setup when you get training.) 7. Set the generator voltage and current to 40 kV and 40 mA. The program will prompt you to set the generator to the “user settings” of 40kV and 20mA. You can select yes for this option, but you will still need to select: Collect – Goniometer – Generator, and then set the values to 40kV and 40mA. 8. Aligning the Sample. In the GADDS-Manual-Chi-Video program, select CollectGoniometer-Laser. Open the Video icon on the desktop. You should see an image of your sample on the computer screen. Adjust the Z-control of the sample holder until the laser spot is in the center of the grid. The x-ray beam is then aligned with the laser. After aligning the sample height, you can translate the sample. When you are done with the alignment, turn the laser off by selecting Collect-Goniometer-Laser. 9. Gently close the enclosure doors. 10. Select 2theta position. Position the detector (2theta), incident angle to the sample (omega) and the sample rotation (phi), using the Collect – Goniometer – Drive option. The 2theta position will be centered in the area collected by the detector. Select one of 2 positions for the sample tilt (chi), either 90 degrees with the sample in the vertical position or 54.74 degrees with the sample in the tilted position. To change the Chi position on the GADDS screen, go to Collect – Goniometer – Fixed Axes. 11. Collecting Data. Select Collect – Add. Enter the number of seconds to accumulate data (minutes are entered 1:00). The files accumulated in the Add option are not automatically saved. You must select File – Save. Data is stored in the C: drive, in the shared folder: Frames. To stop the data acquisition before it is completed, use ctrl-C. The data may be saved in the normal way. Whenever you start to collect diffraction data, you will be prompted with a window that will indicate the sample to detector distance, and the x and y position of the center of the detector. These values are determined during the calibration of the system and are recorded in the notebook next to the GADDS computer. Make sure that the sample-todetector distance is correct before you start collecting data. If you need to change these values, select Edit – Configure – User settings, and enter the correct values from the notebook. If you change the settings, several questions will appear on the screen; answer “yes” to all of them. 12. ANALYSIS Analysis of the data depends on the information that you require. Textural information and peak positions are obtained using the GADDS software. Phase identification is done in conjunction with the JADE program which runs on the computers in Snee 1158. 1. Unwarp the data. Select Process – Spatial – Unwarp. The current frame is indicated by $frame. 2. Integrate the data. Peak – Integrate – Chi will integrate over a range of Chi angles and through a range of 2theta angles to produce an x-y plot of intensity versus 2theta. Selecting Peak – Integrate – 2Theta will generate a plot of intensity versus Chi. The integrated data may be stored as a text file (Plotso) or as a DiffracPlus (.raw) which can be used in JADE. Frames may be printed using the File – Print option. Make sure that the printer (output print filename) selected is the HP2600N and that the output format selected is native. 13. Shutdown Select Collect – Goniometer – Generator option to bring the generator down to 20 kV and 5 mA. Exit out of the GADDS program (& the Video program if it is still running). Turn off the AC power to the detector bias controller. Turn off the X-ray generator. Turn off the instrument with the red button on the front right corner of the instrument. Remove your sample from the sample holder. 14. Additional Procedures Error code 30. This indicates a problem with the interlocks in the door. This message can sometimes be cleared by pressing the “clear alarm” button (top left under enclosure doors) and re-starting the generator. Try the following procedure: Open the enclosure doors. Press the warming current button on the generator. Press the “clear alarm” button. Press the ON button on the x-ray generator. (Remember to bring the voltage and current back up to 40kV and 40mA.) 15. Signing up for instrument time: Sign-up for instrument time is done on Coral. You are responsible for the time that you sign up for. If you can not use the time and do not cancel it ahead of time, you will be charged for it. 16. File Backup: You are responsible for backing up your own files. 17. Disable the instrument in Coral when you are finished.