The SiW-ECAL prototype of CALICE visits DESY II

During 2021 a stack with 15 layers of short slabs, equivalent to 15360 readout cells, has been compiled. The different photographs in this blog entry allow
appreciating the high density at the layer extremities. This is already close to what is expected in a final experiment at a Higgs factory.

The testbeam carried at DESY in November 2021  is the most important system test of the new compact DAQ so far. The fifteen single modules (consisting of one single active unit sensor -ASU- and the electronic readout cards -SLboard – ) are interleaved with 14 tungsten plates with a thickness of 2.1 mm (x11) and 4.2 mm (x3) yielding an overall depth of 9.6 radiation lengths (X0). This test is the kick-off of a series of beam tests to be carried at CERN by the CALICE collaboration. In these testbeams, a set of ECAL and HCAL prototypes will record and study the interactions of high energetic leptons and hadrons beams.

The first week of the beam test was dedicated to the optimization of the system (auto threshold determination, characterization of the ASICs, etc) and the single cell calibration. For that, we used the detector in the «tracker» configuration (i.e. without tungsten plates) and used the 3 GeV positron beam as MIP-like beam source. We recorded millions of MIP-like interactions per layer. For the second week, we added the tungsten plates and started the electromagnetic shower program. We made several scans varying the beam position and the energy of the beam, which at DESY is tunable between 1 and 6 GeV.

All this has been possible thanks to the support of DESY and the test beam coordinators. The full test beam has been performed following the strict regulations against the spread of covid19 that allows that the DESY II facility still offers the possibility for external group to access to beam time, key for the test and development of every detector R&D program.

Part of the debugging and mounting process is documented in the set of photographs posted below. We also show a nice event display with a electromagnetic shower recorded with the prototype.

The AITANA group has played an important role in the preparation, setting up and data taking coordination for this testbeam. Adrián Irles has been the Run Coordinator for the two weeks. In addition, Jesús P. Márquez, has also participated attending during the first week, experiencing for first time a test beam.