I know, it has been a while since my last post. I also realize that I’m writing openings like this all too frequently lately: Too much work to do, in particular many things that involve writing of some document or other, but of course also a few trips here and there. Right now, I’m on my way to Hamburg for two days, and last week, I spent two days at CERN. As usual, two days packed with various meetings, but I also had the time to see how the preparations for this years CALICE Tungsten HCAL test beams are going.
After a first, very successful beam period last year, this year we are going for high energies at the CERN SPS. First beam is less than two weeks away, so we are busy with preparations. These tests are absolutely crucial: The Tungsten HCAL (for a very brief answer to the obvious question: Why Tungsten? See here… ) we are testing is, after all, a prototype for a calorimeter at CLIC, where we expect very high-energetic particles and jets. These high energies are actually the motivation for using expensive Tungsten, so we better also test our detectors with highly energetic particles.
Puting things back together: Installing Tungsten plates for the CALICE Tungsten HCAL test beam due to start in less than two weeks.
Last year, our first commissioning test was performed at the CERN PS, where we got various particles at energies up to 10 GeV. There are several good reasons to start there: Testing at low energies is interesting, in particular from the point of view of understanding the shower physics and comparing to simulation models. Also, testing at the PS is more relaxed: While the test beam time at the SPS is notoriously oversubscribed, causing very tight schedules, things are a bit easier at the PS, allowing for more time to understand complex systems that get operated for the first time.
Now, we are getting ready for the SPS, with energies all the way up to several hundred GeV, which will show us how big the advantage of using Tungsten instead of Steel really is. A first step of of that I could see last week: The Tungsten absorber structure is getting reassembled, with a few more layers compared to last year. Each of the absorber layers weighs more than 100 kg, so they are lifted in place by crane. What I was looking at in particular was the last layer, clearly visible in the picture: This is just an empty aluminum frame, which will hold a special little experiment run by my group, which already took data last year. From that, we have first results, and I promise to write a post about that, too… This time, I hope you will not have to wait too long.
