As part of its HL-LHC upgrade program, the CMS Collaboration is developing a High Granularity Calorimeter (CE) to replace the existing endcap calorimeters. The CE is a sampling calorimeter with unprecedented transverse and longitudinal readout for both electromagnetic (CE-E) and hadronic (CE-H) compartments. The calorimeter will be built with ∼30,000 hexagonal silicon modules. Prototype modules have been constructed with 6-inch hexagonal silicon sensors with cell areas of 1.1 cm 2 , and the SKIROC2-CMS readout ASIC. Beam tests of different sampling configurations were conducted with the prototype modules at DESY and CERN in 2017 and 2018. This paper describes the construction and commissioning of the CE calorimeter prototype, the silicon modules used in the construction, their basic performance, and the methods used for their calibration.

Concomitant with this increase will be an increase in the number of interactions in each bunch crossing and a significant increase in the total ionising dose and fluence. One part of this upgrade is the replacement of the current endcap calorimeters with a high granularity sampling calorimeter equipped with silicon sensors, designed to manage the high collision rates [2]. As part of the development of this calorimeter, a series of beam tests have been conducted with different sampling configurations using prototype segmented silicon detectors. In the most recent of these tests, conducted in late 2018 at the CERN SPS, the performance of a prototype calorimeter equipped with ≈12, 000 channels of silicon sensors was studied with beams of high-energy electrons, pions and muons. This paper describes the custom-built scalable data acquisition system that was built with readily available FPGA mezzanines and low-cost Raspberry PI computers.

For the CMS High Granularity Calorimeter (CE), the final version of the 72-channel front-end ASIC (HGCROC3) was submitted in December 2020. HGCROC3 includes low-noise/high-gain preamplifiers/shapers and a 10-bit 40 MHz successive approximation ADC (SAR-ADC) that provide the charge measurement over the linear range of the preamplifier. In the saturation range, a discriminator and a time-to-digital converter (TDC) provide the charge information from the time over threshold (ToT; 200 ns dynamic range, 50 ps binning). A fast discriminator and another TDC provide timing information to 25 ps accuracy. The chip embeds all necessary ancillary services: bandgap circuit, PLL, threshold DACs. We present the experimental results on the latest and final version (HGCROC3) received in April 2021.

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A radiation-hard BGR (bandgap voltage reference) circuit is here presented. It's able to maintain the output voltage accuracy over process, voltage, and temperature (PVT) variations, combined with extremely high total-ionizing-dose (up to 800 Mrad (SiO 2 )), as required by the next experiments upgrades of the Large Hadron Collider (LHC). The design has been dealt starting from several experimental results, collected from some testing devices, under radiation exposure. In particular, this information has been used modifying the model files provided by foundry, in order to consider the radiation exposure effects during the design process. Consequently, a rad-hard optimized sizing device has been devised. In addition, a particular layout solution has guaranteed a better radiation immunity for the temperature sensing elements (i.e., diodes). The bandgap reference circuit has been fabricated in a commercial 65 nm CMOS technology. Measurement results show a temperature coefficient of about 130 ppm/ • C over a temperature range of 120 • C (from −40 • C to 80 • C, as required by application) and a variation of 0.3% for Vdd 1.08 V-1.32 V. The mean value of the BGR output is about 330 mV, with a 10% maximum shift when exposed up to 800 Mrad (SiO 2 ). The power consumption is 240 µW at room temperature, with a core area of 0.018 mm 2 .