Silicon Tungsten Research Articles

New results of the technological prototype of the CALICE highly granular silicon tungsten calorimeter

An extended version of the CALICE silicon–tungsten ECAL, with 15 active layers, was tested in November 2021 at the DESY beam test facility. Respectively with the previous design, it featured some complete layers with a thin PCB design, and a new compact DAQ handling 15 layers in a common set. The noise, self-trigger performance and response to punch-though electrons, without tungsten absorbers, was evaluated for each of the 15,360 channels, using an improved procedure. Showers of low-energy electrons (1 to 5 GeV) have been recorded in two configuration of absorber, and are being analysed. Some preliminary results will be shown here.

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.

Results from the EPICAL-2 ultra-high granularity electromagnetic calorimeter prototype

A prototype of a new type of calorimeter has been designed and constructed, based on a silicon–tungsten sampling design using pixel sensors with digital readout. It makes use of the ALPIDE sensor developed for the ALICE Inner Tracking System (ITS) upgrade. A binary readout is possible due to the pixel size of ≈30×30μm2. This prototype has been successfully tested with cosmic muons and with test beams at DESY and the CERN SPS. We report on performance results obtained at DESY, showing good energy resolution and linearity, and compare to detailed MC simulations. Also shown are preliminary results of the high-energy performance as measured at the SPS. The two-shower separation capabilities are discussed.

ANUINDRA: A wide dynamic range FEE ASIC for a silicon–tungsten electromagnetic calorimeter

A wide dynamic range (ratio of maximum detectable signal to noise floor) front end electronics (FEE) readout ASIC ANUINDRA has been developed in 0.35μm standard N-well CMOS technology for the prototype forward calorimeter (FOCAL), a silicon–tungsten (Si–W) electromagnetic (EM) calorimeter, proposed as part of the ALICE upgrade at CERN. It is a 16 channel pulse processing ASIC with a multiplexed serial output along with all the individual channel’s responses available as output pins. Each channel consists of a charge sensitive amplifier (CSA), semi-Gaussian pulse shaper, gain-stage, and Track & Hold stage. The ASIC has been designed with a linear operating range of 2.6 pC w.r.t the input charge and a measured charge gain of 1.34 mV/fC. ANUINDRA ASIC shows a noise level (ENC) of 820 e− with 0 pF of detector capacitance. A baseline recovery of better than 1% within 5μs can be attained by adjusting the pole–zero locations with the help of external voltage control. The fabricated and packaged ANUINDRA was successfully tested and characterized in the laboratory and with a high energy particle beam at the SPS beamline in CERN. The design details of ANUINDRA ASIC along with the test results are presented herewith in this paper.

A wide swing charge sensitive amplifier for a prototype Si–W EM calorimeter

A wide swing charge sensitive amplifier (CSA) has been developed, as a part of a front-end electronics (FEE) readout ASIC, for a prototype silicon tungsten (Si–W) based electromagnetic (EM) calorimeter. The CSA, designed in 0.35μm N-well CMOS technology using 5V MOS transistors, has a wide linear operating range of 2.6 pC w.r.t the input charge with a power dissipation of 2.3 mW. A noise figure (ENC) of 820 e− at 0 pF of detector capacitance with a noise slope of 25 e−/pF has been achieved (when followed by a CR-RC2 filter of 1.2μs peaking time). This design of CSA provides a dynamic range (ratio of maximum detectable signal to noise floor) of 79 dB for the maximum input charge of 2.6 pC when connected to a silicon detector with a capacitance of 40 pF. Using folded cascode architecture-based input stage and low voltage high swing current mirrors as the load, the CSA provides an enlarged output swing by biasing the output node towards one supply rail and utilizing the voltage range towards the opposite rail. The design philosophy works for both polarities of a large input signal. This paper presents the design of CSA with a wide negative output swing for an anticipated input signal of positive polarity in the target application with a known detector biasing scheme.

Development and characterization of a large area silicon pad array for an electromagnetic calorimeter

We present the research and development work of the first version of a 6×6 array of silicon pad detectors, carried out in India, for the proposed forward calorimeter (FOCAL) as part of the ALICE collaboration upgrade program at CERN. The primary motivation is to develop a large area silicon pad array realizing the challenging requirements of high-energy physics experiments such as low leakage current, high breakdown voltage and evaluate its performance as an active layer in the prototype silicon tungsten (Si-W) electromagnetic (EM) calorimeter. Towards these goals, a 36-pad silicon sensor with an individual pad size of ∼1 cm2 is designed on a 4-inch high resistivity N-type wafer and fabricated at Bharat Electronics Limited, Bangalore. The sensors have been used to assemble the prototype Si-W calorimeters and were successfully tested with high-energy particle beams. The design and development of the large area silicon sensor and its characterization using radioactive sources in the laboratory and high-energy particle beams are reported in this paper.

Design and performance of a silicon–tungsten calorimeter prototype module and the associated readout

We describe the details of a silicon–tungsten prototype electromagnetic calorimeter module and associated readout electronics. Detector performance for this prototype has been measured in test beam experiments at the CERN PS and SPS accelerator facilities in 2015/16. The results are compared to those in Monte Carlo Geant4 simulations. This is the first real-world demonstration of the performance of a custom ASIC designed for fast, lower-power, high-granularity applications.

Gamma-ray shielding characteristics of flexible silicone tungsten composites

Silicone being a hybrid elastomer is well known for its excellent thermal and mechanical properties, chemical resistance, compatibility with organic and inorganic fillers, nontoxicity, and flexibility. As the reported literature on silicone tungsten composite is rare, thus, a complete possible spectrum of silicone tungsten composites series with tungsten loading of 0–88.1 %wt has been fabricated by RTV method and studied as a flexible gamma shielding material. Flexible silicone/tungsten composite formulations containing different weight percentages of tungsten powder (0, 30.1, 47.8, 59.8, 68.1, and 88.1 wt %) were developed by the room-temperature vulcanization route. Two lead collimators with diameters of 0.6 cm were used to make a narrow beam geometry for gamma rays emitted from a137Cs (gamma-ray energy of 662 keV) point source. Uncollided flux was measured with a NaI(Tl) scintillation detector enclosed in lead shielding to reduce the background radiation level. The measured mass attenuation coefficient for our composites with 88.1 wt % tungsten was 0.1035 cm2/g, which is nearly 3.5% higher than that of commercially available silicone/tungsten composites named T-Flex (nearly 0.095 cm2/g) containing the same tungsten loading. Similarly, superior half value layers (HVL) of our composites with 88.1 % wt loading of tungsten i.e 1.01 cm versus 1.27 cm for the reported T-Flex counterpart with additional advantage of insitu fabrication on complex geometries. It was also found that the effectiveness of gamma-ray shielding increases with increase in density of the composites, which is due to the increase in the weight percent of tungsten powder. Our material will have applications as shielding material for both mobile and stationary radiation sources and it can also be used as fabrication material for gloves, safety shoes, coats, etc. to protect workers in a radiation environment.

ILD silicon tungsten electromagnetic calorimeter first full scale electronic prototype

The “long slab” is a new prototype for the SiW-Ecal, a silicon tungsten electromagnetic calorimeter for the International Large Detector (ILD) at the future International Linear Collider (ILC). The new prototype has been evaluated with cosmics, radioactive sources and with 3 GeV electrons in beam tests at the DESY facility, Hamburg. A channel-wise calibration has been achieved, at different angles of incidence of the beam on the sensors. Using data collected at non-normal incidence, the signal of particles traversing adjacent pixels were used to estimate the absolute value of the trigger threshold in units of mips. This new prototype provides us many hints on how to improve the design of the front-end electronics. It is also a convenient tool to estimate the critical characteristics of ILD SiW-Ecal (like power consumption, cooling, readout time, etc.) and to optimise the future design of the detector.

Recent results of the technological prototypes of the CALICE highly granular calorimeters

The CALICE Collaboration is conducting R&D for highly granular calorimeters with an emphasis on detectors for Linear Colliders. This contribution briefly summarises recent tests of large scale technological prototypes of a silicon tungsten electromagnetic calorimeter and hadron calorimeters featuring either a gaseous medium or scintillator with a SiPM readout as active material.

Evolution of shock waves in oxidefree ceramics by the example of silicon carbide, boron carbide and tungsten carbide

Evolution of shock waves in oxidefree ceramics by the example of silicon carbide, boron carbide and tungsten carbide

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.

Internal alignment and position resolution of the silicon tracker of DAMPE determined with orbit data

The DArk Matter Particle Explorer (DAMPE) is a space-borne particle detector designed to probe electrons and gamma-rays in the few GeV to 10 TeV energy range, as well as cosmic-ray proton and nuclei components between 10 GeV and 100 TeV. The silicon–tungsten tracker–converter is a crucial component of DAMPE. It allows the direction of incoming photons converting into electron–positron pairs to be estimated, and the trajectory and charge (Z) of cosmic-ray particles to be identified. It consists of 768 silicon micro-strip sensors assembled in 6 double layers with a total active area of 6.6 m2. Silicon planes are interleaved with three layers of tungsten plates, resulting in about one radiation length of material in the tracker. Internal alignment parameters of the tracker have been determined on orbit, with non-showering protons and helium nuclei. We describe the alignment procedure and present the position resolution and alignment stability measurements.

Charge reconstruction of the DAMPE Silicon–Tungsten Tracker: A preliminary study with ion beams

The DArk Matter Particle Explorer (DAMPE) is one of the four satellites within Strategic Pioneer Research Program in Space Science of the Chinese Academy of Science (CAS). DAMPE can detect electrons, photons in a wide energy range (5 GeV to 10 TeV) and ions up to iron (100 GeV to 100 TeV). The silicon–Tungsten Tracker (STK) is one of the four subdetectors in DAMPE, providing photon–electron conversion, track reconstruction and charge identification for ions. An ion beam test was carried out in CERN with 60 GeV/u Lead primary beams. Charge reconstruction and charge resolution of the STK detectors were investigated.

Novel silicon–tungsten oxide–carbon composite as advanced negative electrode for lithium-ion batteries

A cheap Si powder byproduct from solar cell production was applied as a negative electrode for lithium-ion batteries. To improve the cycle and rate performances, the as-obtained Si powder was composited with tungsten oxide and coated with carbon, in sequence. After preparing the composite material, its electrochemical performance is evaluated, which exhibits a high reversible capacity of 975mAhg−1 with improved cycleability. Especially, the rate capability is significantly improved to 390mAhg−1 under 1000mAg−1 applied current. This advanced electrochemical performance is attributed to the matrix effect of the formed Li2O and W metal with carbon coating, as identified using ex-situ X-ray diffraction experiments, and associated with the low polarization resistance observed in the galvanostatic charge intermittent technique.

Modelling the Brittle/Ductile Transition in Super-Fine Finishing of Carbides

Materials such as binderless tungsten carbide and silicon carbide have become ubiquitous in the fabrication of high-performance tooling and molding inserts. But while conventional grinding of these hard ceramics has been studied in depth, the theory underlying their super-fine finishing has been less extensively explored. In particular, the boundary in process parameters that delineates the brittle/ductile removal transition remains mostly undocumented. In this paper, we review some super-fine finishing methods for carbide materials, based on both bound and kinetic abrasive processes. The focus is then placed on modelling the interaction between material and abrasives under their respective process conditions, and deriving some useful criteria guiding the brittle/ductile transition.

The microstructure and tribological properties at elevated temperatures of tungsten silicon nitride films

W-Si-N films with various Si contents were deposited using a reactive magnetron system, and the film with the highest hardness, the lowest average friction coefficient (μ) and wear rate at room temperature (RT) was chosen to study the tribological properties at elevated temperature. Tribological properties of the film were performed using un-lubricated sliding tests against an alumina counterpart. Elevating the testing temperature from RT to 100°C induced an intense skin plastic deformation, as a result, the μ increased rapidly and the wear rate decreased significantly. As the testing temperature was in the range of 100–200°C, the surface deformation strengthening was induced furtherly, μ was further increased and the wear rate could not be calculated due the adhesive wear debris on the wear track. From 200 to 600°C, the main wear mechanism changed to oxidation wear and the a lot of WO3 tribo-film led to the decrease of μ. Wear rate increased gradually due to the accelerated oxidation of the film and the disappearance of surface deformation strengthening.

Gasochromic properties of novel tungsten oxide thin films compounded with methyltrimethoxysilane (MTMS)

Thick tungsten–silicon films with long-term gasochromic performance were synthesized from methyltrimethoxysilane (MTMS) and tungsten oxide sols. The WO3–MTMS films exhibited a stable network with tungsten and silicon bonds.

Preliminary conceptual design about the CEPC calorimeters

The Circular Electron Positron Collider (CEPC) as a Higgs factory was proposed in September 2013. The preliminary conceptual design report was completed in 2015.1 The CEPC detector design was using International Linear Collider Detector — ILD2 as an initial baseline. The CEPC calorimeters, including the high granularity electromagnetic calorimeter (ECAL) and the hadron calorimeter (HCAL), are designed for precise energy measurements of electrons, photons, taus and hadronic jets. The basic resolution requirements for the ECAL and HCAL are about 16%[Formula: see text][Formula: see text] (GeV) and 50%[Formula: see text][Formula: see text] (GeV), respectively. To fully exploit the physics potential of the Higgs, [Formula: see text], [Formula: see text] and related Standard Model processes, the jet energy resolution is required to reach 3%–4%, or 30%/[Formula: see text] (GeV) at energies below about 100 GeV. To achieve the required performance, a Particle Flow Algorithm (PFA) — oriented calorimetry system is being considered as the baseline design. The CEPC ECAL detector options include silicon–tungsten or scintillator–tungsten structures with analog readout, while the HCAL detector options have scintillator or gaseous detector as the active sensor and iron as the absorber. Some latest R&D studies about ECAL and HCAL within the CEPC working group is also presented.

The DAMPE silicon–tungsten tracker

The DArk Matter Particle Explorer (DAMPE) is a spaceborne astroparticle physics experiment, launched on 17 December 2015. DAMPE will identify possible dark matter signatures by detecting electrons and photons in the 5GeV–10TeV energy range. It will also measure the flux of nuclei up to 100 TeV, for the study of the high energy cosmic ray origin and propagation mechanisms. DAMPE is composed of four sub-detectors: a plastic strip scintillator, a silicon–tungsten tracker–converter (STK), a BGO imaging calorimeter and a neutron detector. The STK is composed of six tracking planes of 2 orthogonal layers of single-sided micro-strip detectors, for a total detector surface of ca. 7m2. The STK has been extensively tested for space qualification. Also, numerous beam tests at CERN have been done to study particle detection at silicon module level, and at full detector level. After description of the DAMPE payload and its scientific mission, we will describe the STK characteristics and assembly. We will then focus on some results of single ladder performance tests done with particle beams at CERN.