As usual, members of the CMBeam team participated in the European Science Night. Here in Iceland this is called Vísindavaka. As before, our booth was equipped with our 2.4-m gravity simulator which is always a big hit. We find that the most effective demonstration by far involves splitting the kids into two groups and then asking the groups to toss marbles into opposite directions. We subsequently get a lot of collisions and marbles falling into the center of the gravity well. The marbles that survive are typically all rotating in the same direction, just like the planets in our solar system :)

It has been 2 months since we started working on assembly and leak checking of the cryostat vacuum vessel at Héðinn. During this time, we discovered some issues with welds that needed to be fixed. As you would expect, we also discovered some aspects of the design that would be done differently if we were to repeat this exercise.

We were really lucky to have excellent support from Héðinn during this time. They kindly agreed to house and feed us while we went through the process and give us access to their excellent infrastructure. This led to a really fast repair and testing turnaround. In the end, we pumped down the vacuum vessel 10 times and spent a minimum of 12 work days during this period. The last of these visits happened on May 22 when we could not reliably detect any leaks in the vacuum vessel. The cryostat was shipped to the University of Iceland on May 26 :)

P.S: One of the most surprising discoveries from this effort was how reliably we could localize leaks in welds through the use of butyl rubber. We simply pressed the rubber firmly against the suspect area and found that pressure and/or leak rate would drop significantly.