Glovebox where we pack targets

Tray of targets ready to be packed...


Target Packing

University of Vermont

Targets drying and ready to be burned

When the samples have dried completely they are ready to be packed into targets. First, put on a clean pair of gloves and label a target holder and target for each sample. Place the labeled target into the labeled target holder upside down. Make sure to use Be targets for the Be fractions (these targets are aluminum) and Al targets for the Al fractions (these targets are stainless steel). Use a blue pen to label Be targets, and a black pen for Al. Once everything has been labeled, set these aside.

Sample oxidation should be done in a hood. Target preparation should be done in the glove box.

Use a gas flame to oxidize each sample. Use a pair of tongs to remove the crucible from the drying block. (Before using the tongs, check that no chrome is flaking off. Use sand paper and fine steel wool to remove any flakes.) Place sample in the flame, directly above the blue tip of the flame. Once the sample begins to glow orange, leave it in the flame for one minute. USE THE TIMER. After the sample has been oxidized put the crucible back in the proper position. Repeat for each sample.

Using a clean pair of gloves add Ag to each sample in a proportion approximately 1:1 (Ag:Sample). Use more Ag for very small samples. MAKE SURE THAT THE Ag SCOOP DOES NOT TOUCH ANY OF THE SAMPLE CRUCIBLES. Add first to Al samples, going from 1 to 8. Turn the blocks around and add to the Be samples. Remember to turn the blocks back around after adding Ag.

Place the stainless steel target packing tray in a hood. First set up the funnels and tampers, then the target holders. CHECK AGAIN TO MAKE SURE THAT THE TARGET HOLDERS ARE IN BATCH ORDER. Make sure to duplicate the order of samples on the batch sheet when you set up the target holders. Load quartz vials containing samples last, being sure to attain proper order and avoid cross-contamination. Note that for targets, the Beryllium are in the front row, whereas for the quartz vials, the Aluminum are in front. See color key on packing tray. BLUE for Be. ORANGE for Al.

Before moving the tray to the glove box, put the jar for used funnels in the glove box. Also make sure there are Kim wipes, a water bottle, and a Beryllium waste bag in the glove box. MAKE SURE LOADING DOOR IS OPEN. Carefully carry the packing tray over to the glove box. Put it in the atrium to the box, resting on the ledge. Close the door to the atrium. Check that the glove box fan is OFF, and that the light and static control are ON. Get settled with the gloves on, and move the tray carefully to the center of the working area. Align it so the tampers are on your left, and the quartz vials on your right. Use this configuration until it becomes difficult to reach the farther samples, then turn the tray around.

Check that the post on the target stand is tight. Always do the Beryllium vial first, then use the same funnel and tamper to do the Aluminum vial of the same sample. Pick up the first Beryllium target, check that the label is correct and that it is the same on both the holder and the target. Put the target on the target stand. Put the first funnel over the target. Remove the first Be vial from the tray using index and middle fingers to avoid holding glove over the open vial. Pick up the tamper from the bottom end and use the clean end to grind the sample/Ag mixture and mix them thoroughly. Make sure the sample is well powdered and the Ag is mixed in well. This may take several minutes. Transfer the powder to the hole in the funnel. Grind the vial a second time and transfer any remaining powder to the funnel. Tap the side of the funnel and spin it around to make sure the powdered sample goes through to the target. Remove the funnel, being careful not to dislodge the target with it, and place it back in its location on the packing tray. Use a hammer to tap the tamper into the hole and pack the powder down. Target should only be filled 1/2 to 2/3 of the way to the top. If there is extra powder, prepare another target and label it with the sample number followed by (2) (ex. KM95-3 (2)). Make sure the sample is packed well into the target. Put the target back into the labeled target holder upright, and set aside. Discard the quartz vial in the Beryllium waste bag. Re-use the funnel and tamper for the Aluminum target of the same sample, then dispose of the tamper in the waste bag. Place the used funnel in the dirty funnel jar.

Before starting next sample, wipe down the working surface, the target holder, and your gloves with moist Kim wipes. Repeat above procedure for each sample.

After packing is finished, put samples into small ziplocks and label with isotope (Al or Be) and batch number. Lock samples in grey case.

Wash funnels according to written procedures. Rinse the packing tray with 1% nitric followed by nanopure water, then dry it in the oven.

Samples are now ready for analysis on an AMS!