SiW ECAL Research Articles

The CALICE SiW ECAL Technological Prototype—Status and Outlook

The next generation of collider detectors will make full use of Particle Flow Algorithms, requiring high-precision tracking and full imaging calorimeters. The latter, thanks to granularity improvements by two to three orders of magnitude compared to existing devices, have been developed during the past 15 years by the CALICE collaboration and are now reaching maturity. This contribution will focus on the commissioning of a 15-layer prototype of a highly granular silicon–tungsten electromagnetic calorimeter that comprises 15,360 readout cells. The prototype was exposed in November 2021 and March 2022 to beam tests at DESY and in June 2022 to a beam test at the SPS at CERN. The test at CERN has been carried out in combination with the CALICE Analogue Hadron Calorimeter. The contribution will give a general overview of the prototype and will highlight technical developments necessary for its construction.

CALICE SiW ECAL—development and test of the chip-on-board PCB solution

The highly granular silicon-tungsten electromagnetic calorimeter (SiW ECAL) is the reference design of the ECAL for the International Large Detector (ILD) concept, one of the two detector concepts proposed for the future International Linear Collider (ILC). Prototypes for this type of detector are developed within the CALICE Collaboration. This contribution reports on the development of an ultra-thin PCB called Chip-on-Board (COB) that is equipped with wirebonded ASICs and pixelated silicon wafers. This set will form the basic unit of detection of the SiW ECAL. It will favour the design of an ultra compact calorimeter since these boards feature a thickness of 1.2 mm to be compared with the 3 mm of the default solution variant using ASICs in BGA packaging. We report also on the first results obtained with the COB boards on a beam test at DESY.

CALICE SiW ECAL—Development and performance of a highly compact digital readout system

A highly granular silicon-tungsten electromagnetic calorimeter (SiW-ECAL) is the reference design of the ECAL of the International Large Detector (ILD) concept, one of the two detector concepts for the detector(s) at the future International Linear Collider. Prototypes for this type of detector are developed within the CALICE Collaboration. During the last year a highly compact digital readout system has been built. The system has been used for the first time in a beam test in Summer 2019 at DESY. This article summarises the main features of the system and report on its performance during the beam test.

Characterisation of different stages of hadronic showers using the CALICE Si-W ECAL physics prototype

A detailed investigation of hadronic interactions is performed using $\pi^-$-mesons with energies in the range 2--10 GeV incident on a high granularity silicon-tungsten electromagnetic calorimeter. The data were recorded at FNAL in 2008. The region in which the $\pi^-$-mesons interact with the detector material and the produced secondary particles are characterised using a novel track-finding algorithm that reconstructs tracks within hadronic showers in a calorimeter in the absence of a magnetic field. The principle of carrying out detector monitoring and calibration using secondary tracks is also demonstrated.

A SKIROC2-based prototype electronics system for silicon PIN array

Silicon PIN (Si-PIN) diode has been widely used in high-energy physics experiments. The next-generation experiments ask for a large amount of the Si-PIN diode arrays, leading to a requirement for the electronics system with features of higher integration and lower power consumption than the traditional ones. The aim was to design and implement a prototype of multi-channel electronic system, which is based on the SKIROC2 ASIC. The system is also considered as the pre-research of the silicon–tungsten (Si-W) ECAL for CEPC. The prototype is divided into two parts, so that it has the potentiality for the expansion of more readout channels. The front-end board (FEB), which carries a Si-PIN diode array and an ASIC of SKIROC2 on it, provides high voltage to the Si-PIN diodes and processes the signals as well. The FEB is configured by a data interface board (DIF) and sends data to the DIF, which then transfers data to PC via USB interface after packing process. The prototype electronics system has been implemented. The equivalent noise level of all the 64 channels is below 0.4 fC. The dynamic range is up to +3000 fC with an integral nonlinearity (INL) of 0.2 %, and the gain non-uniformity is better than 5 %. The energy resolution with 59 keV X-rays from 241Am is about 13.3 % (in RMS), while the signal-to-noise ratio (SNR) reaches about 10.9 for minimum ionizing particles (MIPs). In this paper, a SKIROC2-based prototype electronics system for Si-PIN array, as well as the performance test, has been presented. The system has features of high integration, low noise, and high dynamic range. The SKIROC2, as well as the design concept of the electronics system, can be applied to the preliminary prototype Si-W ECAL of CEPC.

Energy reconstruction of hadrons in highly granular combined ECAL and HCAL systems

This paper discusses the hadronic energy reconstruction of two combined electromagnetic and hadronic calorimeter systems using physics prototypes of the CALICE collaboration: the silicon-tungsten electromagnetic calorimeter (Si-W ECAL) and the scintillator-SiPM based analog hadron calorimeter (AHCAL); and the scintillator-tungsten electromagnetic calorimeter (ScECAL) and the AHCAL. These systems were operated in hadron beams at CERN and FNAL, permitting the study of the performance in combined ECAL and HCAL systems. Two techniques for the energy reconstruction are used, a standard reconstruction based on calibrated sub-detector energy sums, and one based on a software compensation algorithm making use of the local energy density information provided by the high granularity of the detectors. The software compensation-based algorithm improves the hadronic energy resolution by up to 30% compared to the standard reconstruction. The combined system data show comparable energy resolutions to the one achieved for data with showers starting only in the AHCAL and therefore demonstrate the success of the inter-calibration of the different sub-systems, despite of their different geometries and different readout technologies.

Performance study of SKIROC2/A ASIC for ILD Si-W ECAL

The ILD Si-W ECAL is a sampling calorimeter with tungsten absorber and highly segmented silicon layers for the International Large Detector (ILD), one of the two detector concepts for the International Linear Collider. SKIROC2 is an ASIC for the ILD Si-W ECAL. To investigate the issues found in prototype detectors, we prepared dedicated ASIC evaluation boards with either BGA sockets or directly soldered SKIROC2. We report a performance study with the evaluation boards, including signal-to-noise ratio and TDC performance with comparing SKIROC2 and an updated version, SKIROC2A.

Technical instrumentation R&D for ILD SiW ECAL large scale device

Calorimeters with silicon detectors have many unique features and are proposed for several world-leading experiments. We describe the R&D program of the large scale detector element with up to 12 000 readout channels for the International Large Detector (ILD) at the future e+e− ILC collider. The program is focused on the readout front-end electronics embedded inside the calorimeter. The first part with 2 000 channels and two small silicon sensors has already been constructed, the full prototype is planned for the beginning of 2018.

Latest R&D news and beam test performance of the highly granular SiW-ECAL technological prototype for the ILC

High precision physics at future colliders as the International Linear Collider (ILC) require unprecedented high precision in the determination of the energy of final state particles. The needed precision will be achieved thanks to the Particle Flow algorithms (PF) which require highly granular and hermetic calorimeters systems. The physical proof of concept of the PF was performed in the previous campaign of beam tests of physic prototypes within the CALICE collaboration. One of these prototypes was the physics prototype of the Silicon-Tungsten Electromagnetic Calorimeter (SiW-ECAL) for the ILC. In this document we present the latest news on R&D of the next generation prototype, the technological prototype with fully embedded very front-end (VFE) electronics, of the SiW-ECAL. Special emphasis is given to the presentation and discussion of the first results from the beam test done at DESY in June 2017. The physics program for such beam test consisted in the calibration and commissioning of the current set of available SiW ECAL modules; the test of performance of individual slabs under 1T magnetic fields; and the study of electromagnetic showers events.

SiW ECAL for future e+e− collider

Calorimeters with silicon detectors have many unique features and are proposed for several world-leading experiments. We discuss the tests of the first three 18×18 cm2 layers segmented into 1024 pixels of the technological prototype of the silicon-tungsten electromagnetic calorimeter for a future e+e− collider. The tests have beem performed in November 2015 at CERN SPS beam line.

Reconstruction and classification of tau lepton decays with ILD

Tau lepton decays with up to two \(\pi ^0\)s in the final state – \(\tau ^+ \rightarrow \pi ^+ \bar{\nu }_\tau \), \(\rho ^+ (\pi ^+\pi ^0) \bar{\nu }_\tau \), and \(\mathrm {a}_{1}^{+}(\pi ^+\pi ^0\pi ^0) \bar{\nu }_\tau \) – are used to study the performance of the barrel region of the silicon-tungsten electromagnetic calorimeter (Si-W ECAL) of the International Large Detector (ILD) at the future \(\mathrm{e}^{+} \mathrm{e}^{-} \) International Linear Collider. Correct reconstruction of the tau decay mode is crucial for constraining the spin state of tau lepton and measuring the Higgs boson CP state in \(\mathrm{H}{}{} \rightarrow \tau ^+\tau ^-\) decays. We find that about 95 % of \(\pi ^+ \bar{\nu }_\tau \), and 90 % of \(\rho ^+\bar{\nu }_\tau \) and \(\mathrm {a}_{1}^{+}\bar{\nu }_\tau \) decays produced by the \(\mathrm{e}^{+} \mathrm{e}^{-} \rightarrow {\mathrm{Z}^{0}}^*\rightarrow \tau ^+\tau ^-\) process at an \(e^\pm \) beam energy of 125 GeV are correctly reconstructed. In a smaller ILD detector, with the inner Si-W ECAL radius reduced by about 20 %, these efficiencies are reduced by at most 2 %. The \(\pi ^0\) mass resolution remains below 10 %. Since failures in tau lepton reconstruction are mainly due to photons, an increase of the ILD magnetic field from 3.5 to 4 T does not bring any significant improvement.

Development of readout interconnections for the Si-W calorimeter of SiD

The SiD collaboration is developing a Si-W sampling electromagnetic calorimeter, with anticipated application for the International Linear Collider. Assembling the modules for such a detector will involve special bonding technologies for the interconnections, especially for attaching a silicon detector wafer to a flex cable readout bus. We review the interconnect technologies involved, including oxidation removal processes, pad surface preparation, solder ball selection and placement, and bond quality assurance. Our results show that solder ball bonding is a promising technique for the Si-W ECAL, and unresolved issues are being addressed.

R&D for a SiW Electromagnetic Calorimeter for a Future Linear Collider

This article presents an overview on the status and perspectives of a highly granular silicon tungsten electromagnetic calorimeter (SiW Ecal) conceived for the operation at a future linear electron-positron collider. Prototypes for this kind of calorimeters are developed within the R&D program of the international collaboration CALICE. This article reports on results on the "pure" calorimetric performance of a first physics prototype with an energy resolution of about and an angular resolution of about 100mrad. Beyond that, emphasis is put on the merits of the high granularity which is indispensable for the achievement of the envisaged physics goals of a linear collider. This high granularity permits the application of image processing algorithms for particle separation as well as it reveals a more detailed view into hadronic cascades than was possible hitherto.

Hadronic showers in the CALICE calorimeter prototypes

The CALICE collaboration has constructed highly granular electromagnetic and hadronic calorimeter prototypes to evaluate technologies for the use in detector systems at the future International Linear Collider. These calorimeters have been tested extensively in particle beams at CERN and at Fermilab. We present preliminary results of an analysis of hadronic events in the combined system under test at CERN in 2006 and 2007, comprising a SiW ECAL, a scintillator tile HCAL and a scintillator strip tail catcher, the latter two with SiPM readout. The properties of hadronic showers in the HCAL, compared to simulations performed with GEANT4, are discussed. Particular emphasis is placed on the study of the linearity of the detector response and on the single particle energy resolution achievable with simple weighting algorithms based on the local energy density in the hadronic showers.