Ponente
Descripción
The LHCb Upgrade II aims at operating the detector at an increased luminosity of up to 1.5 x 10$^{34}$ cm$^{-2}$ s$^{-1}$ to fulfill the goal of recording 300 fb$^{-1}$ of data. The corresponding increase in particle density and radiation dose requires a substantial improvement of the performance of the electronic calorimeter, specially in its central region. Additionally, the increase in pile-up will result in a more complex event profile requiring a larger effort in terms of reconstruction and noise rejection. Before Upgrade II, an enhancement of the detector is planned for LHC Long Shutdown 3, based on the R&D effort done so far, whilch will reduce the occupancy and mitigate substantial ageing effects in the central region.
PicoCal is the multi-technology calorimeter proposed to cope with the challenges of LHCb Upgrade II. The long-standing R&D efforts cover different sampling calorimeter configurations, such as Spagheti Calorimeter (SpaCal) and Shashlik. Inorganic crystal garnets are considered as scintillator for the regions with the hardest radiation environment, while organic scintillators will cover the wider regions. Also wavelength shifting (WLS) fibres are being tested to enhance the light collection process and its timing in the Shashlik configuration. Studies on the production of tungsten and lead SpaCal absober are also ongoing to achieve the Moliere radius imposed by the particle density, including casting and 3D printing processes. Additionally, extensive studies are being performed on different photomultiplier tubes (PMT) and their coupling to the scintillators and the readout system, with special emphasis on achieving a time resolution in the order of ten picoseconds to relax the reconstruction effort.
A chipset is under development to produce energy and time measurements from the PMT pulses. The energy measurement, performed by ICECAL65 ASIC, strongly relies on analog signal processing and per-channel dedicated synchronization, with differential operation to limit noise, rail-to-rail inputs and outputs to fully profit from the voltage dynamic range. On the other hand, the time measurement, covered by SPIDER ASIC, relies on fast waveform sampling using analog memories. This chipset will be hosted in a channel dense front-end board (FEB) governed by an FPGA and including an acquisition and conditioning stage to adapt and distribute the PMT signal to each ASIC.
This work covers the current status and target performance of the different elements of PicoCal. The presentation will also include testbeam results showing that an energy resolution of 10%/sqrt(E) sampling term and 1% constant term and a time resolution of 20ps are achievable with the proposed technologies.
