Speaker
Description
In the next years the Large Hadron Collider will enter its High-Luminosity (HL-LHC) phase. The instantaneous luminosity will increase from about $2 \times 10^{34}cm^{-2}s^{-1}$ to $5-7 \times 10^{34}cm^{-2}s^{-1}$ and, accordingly, the number of pileup interactions will increase from about 60 to 140-200.
All CMS subsystems will be upgraded in order to maintain the current physics performance. In addition, a MIP Timing Detector (MTD) for charged particles will be constructed. MTD has a target time resolution of 30 − 60 ps, allowing to distinguish the primary vertices of tracks using timing information, therefore mitigating the pileup. The detector will be positioned between the tracker and the electromagnetic calorimeter. MTD is divided into two regions, the Barrel/Endcap Timing Layers (BTL/ETL).
The active elements of BTL are arrays of Lutetium-yttrium-orthosilicate (LYSO) scintillating bars doped with cerium (LYSO:Ce), each readout by two silicon photo-multipliers (SiPM) arrays. For precision timing purpose at HL-LHC, LYSO is an optimal candidate, because of its radiation hardness, high light yield (40k photons/MeV), high density, fast rise time (<100 ps) and decay time around 40ns.
The quality of BTL LYSO crystals in the production phase will be monitored in a dedicated laboratory in INFN-Rome1, for a sample of arrays and single crystals. With the same system the crystals were tested in the market-survey phase. In order to ensure mechanical compatibility in the detector assembly, arrays will undergo dimensional measurements via a Coordinate Measuring Machine. LYSO arrays performances will be instead checked using 511 keV annihilation photons, to measure relative light output, optical cross-talk, and time resolution. The crystals production process quality will be monitored through measurements of absolute light yield and decay time, involving a multi-anode photo-multiplier tube and a waveform digitizer, performed on different bars for each crystal ingot.
| Collaboration | CMS - MTD |
|---|---|
| Role of Submitter | I am the presenter |
