Busy times, that’s why I’ve been really slow on the blog lately. Right now, there is a brief downtime, while I’m waiting for a flight from Geneva to Munich, and it’s not worth starting real work, boarding is (hopefully) just 20 Minutes away. I spent the whole day today at CERN, in various meetings. The main purpose for this rather short trip (I arrived here last night) was a meeting to discuss plans for a beam test this fall. We will have two weeks of beam time at the PS (Proton Synchrotron) at CERN for a first test of a hadron calorimeter using Tungsten absorbers. The CALICE HCAL physics prototype I’ve been writing about repeatedly uses steel, so this will be new and exciting. But why use tungsten at all?
A Tungsten plate for our test beam in the fall: Heavy lifting!
This study is motivated by plans for a Linear Collider based on the CLIC technology developed at CERN (I briefly wrote about this a while ago): This machine is aiming for an energy of 3 TeV, quite a bit higher than the ILC. This requires a “deeper” calorimeter, meaning more absorber material to contain the energy of the particles. This is where Tungsten comes in: It is one of the densest materials you can get. The mix we are using has a density of almost 18 g/ccm, that is more than 2 times the density of steel (a bit less than 8 g/ccm). That way, we can built a “thinner” detector, which is crucial to be able to fit everything inside a magnet. At CLIC, the time structure of particle showers is a big issue, and I’m planning a measurement of some aspects of this topic with a special setup to go along with our new Tungsten calorimeter. This calorimeter will use the same active layers, our highly granular scintillator planes, that were also used in previous tests. A team from my group will then add some additional specialized equipment behind the whole setup. Today, we discussed the plans for these measurements, and I also had the opportunity of looking at some of the first Tungsten plates that arrived at CERN. I can hold them up in one hand, but once you grab a plate, you are shocked at the unexpected weight: It is truly heavy lifting!
