Radon Emanation Result of : PICO40L detector O-Rings.

Date: 2022/03/23

The PICO40L detector o-ring was received for radon emanation counting with the low background Radon board system on surface at SNOLAB. The results of PICO40 Vessel Runs (PICO01 and PICO02) were found to be higher than the previous PICO data. It was therefore decided to perform the emantion of the o-ring sample that was used as a seal in the PICO40L vessel. A total of 8 o-rings were emanated. The request for the emanation counting was received in February 2022.

1. Sample Handling

2. Summary of Emanation Counting Results

The sample run for the detector was extracted on February 15, 2022 and counting started on the same day. The detector was emanated for 14.83 days.

For precision measurements, two counting runs are necessary per sample: a Blank (BLK) run with no sample in the chamber and a Sample (SPL) run itself, in which the entire set-up is counted again, but with the sample under study inside the chamber. The net emanation rate (atoms/d) of the sample is obtained by subtracting the BLK rate from the SPL rate. Typically one would perform the Blank runs each time prior to the sample run. But the frequency of Blanks is often reduced due to consistent Blank rates of our system. For the above-mentioned sample, BLK here referes to the Board background run (as the sample was not placed in the chamber). The total efficiency of the Rn board system used for the calculation was: (199.2 +/- 4.5)%.

In this report, only the ²²²Rn emanation rate is presented. It is left to the experiment to determine how to interpret and scale these results based on their radiopurity target.