Packard PPO Sample Preparation at UA



Z. Djurcic and A. Piepke
University of Alabama
(7/9/2001)


A total of 10 large plastic irradiation vials (screw cap type) were prepared for neutron activation at the MIT research reactor on 7/6/2001. Samples of all Packard PPO batches and empty vials (which were subjected to the same treatment) were included. The Packard PPO sample was a mix of the batches: 21-624, 21-625, 21-626, 21-627, 21-630, 21-631, 21-633 and 21-639. The exact contribution of each batch to the total sample weight was not determined but the mix consists to roughly equal parts of the batches listed. The PPO had been received directly from Packard in Holland which had taken the samples when packing the material for shipment to Japan. Batch 21-635 was at hand but not included in the mix as it had been rejected due to its imperfect optical properties. A sample of Dojindo PPO was unfortunately not available and could not be tested. However, the rejected Packard batch 21-635 had been replaced by Dojindo PPO.
All vials were prepared in UA's cleanroom. On 6/18/2001 we determined that the cleanroom air contains 500 particles of 0.5 µm or less per cubic foot of air (class 500).
Prior to filling all vials were double cleaned with high purity HNO3 (U/Th < 10-10 g/g) and in a second step with ultra-high purity HNO3 (U/Th < 10-13 g/g), followed by a rinsing with double de-ionized water. The vials were then dryed in a clean room oven. 6 of the vials were filled with Packard PPO. About 1.0 to 1.3 g of PPO was filled into each vial, leaving about 60% expansion space in the vial. The vials were then melted shut using a soldering iron (which remains in the cleanroom and is only used for this purpose). Every vial was sealed into a secondary containment plastic pouch to contain possible spills. The following table lists all samples prepared for the July 2001 neutron beam time at MIT. Samples displayed in red are blanks, samples shown in blue contain PPO.
UA counting results are referenced to 7/16/2001 (CDT). The rightmost column lists the appropriate shipping delay in hours. All samples were sent to Caltech for final packaing into the irradiation rabbits along with the samples prepared there.

Mass [g] Irradiation (CDT)
Sample Rabbit Empty Full Soldered Begin End Delay [h]
UA46
UA preparation blank		 2 2.6190 2.6175 7/12/2001 23:10 7/13/2001 10:10 84
UA49
Same as above but not soldered shut		 2.6093
CIT46
UA preparation blank		 2.5797 2.5886
CIT49
Same as above but not soldered shut		 2.5995
UA45
Packard batch 21-634		 3 2.5897 3.8535 3.8531 7/13/2001 10:14 7/13/2001 11:14 84
UA47
Packard batch mix		 2 2.5807 3.5563 3.5558 7/12/2001 23:10 7/13/2001 10:10 84
UA48
Packard batch mix		 2.6036 3.5722 3.5717
CIT45
Packard batch 21-634		 3 2.5832 3.9875 3.9865 7/13/2001 10:14 7/13/2001 11:14
CIT47
Packard batch mix		 2.5716 3.6166 3.6153
CIT48
Packard batch mix		 2.5950 3.7561 3.7599


Upon receipt at UA on 7/17/2001 it was noted that samples UA46, 53 and 56 (see Caltech sample page for additional sample description) had cracked irradiation vials.

This page is maintained by A. Piepke
Last update September 8, 2001