Silicon Pad Research Articles

Beam test of n-type Silicon pad array detector at PS CERN

This work reports the test of an n-type silicon pad array detector at the CERN PS in the context of the future Forward Calorimeter (FoCal) detector. FoCal is a proposed upgrade in the ALICE detector operating within the pseudorapidity range of 3.2 < η < 5.8. It aims to measure direct photons, neutral hadrons, vector mesons, and jets for the study of gluon saturation effects in the unexplored region of low momentum fraction x (∼ 10-5–10-6). The prototype is a 8×9 n-type Si pad array detector with each pad occupying one cm2 area, fabricated on a 6-in, 325 ± 10 μm thick, and high-resistivity (∼ 7 kΩ cm) Si wafer, which is readout using the HGCROCv2 chip. The detector is tested using pion beams of energy 10 GeV and electron beams of energy 1–5 GeV. The measurements of the Minimum Ionizing Particle (MIP) response of pions and the shower profiles of electrons are reported.

The forward calorimeter of the ALICE experiment at CERN LHC

A new forward calorimeter (FoCal), covering the pseudorapidity range 3.4 ≤ η ≤ 5.8, is proposed in order to extend the physics reach of ALICE during the LHC Run 4. The FoCal comprises a high-granularity electromagnetic calorimeter with silicon pixel and pad readout as well as a hadronic calorimeter. FoCal gives access to the nuclear gluon densities down to Bjorken-x ∼ 10−6, where they are not constrained by other measurements and their evolution may be affected by non-linear effects of quantum chromodynamics. The hadronic subsystem of FoCal (FoCal-H) will be based on capillary copper tubes with scintillating fibers inside. A full-length prototype was assembled and it was exposed to a non-separated charged particle beam in the H2 SPS CERN beamline in November 2022. An energy scan from 60 to 350 GeV was performed and the reconstructed signals are processed in a custom developed ROOT based environment. The design of the 2022 prototype as well as the first results from the energy reconstruction are presented.

Neutron irradiation and electrical characterisation of the first 8” silicon pad sensor prototypes for the CMS calorimeter endcap upgrade

As part of its HL-LHC upgrade program, the CMS collaboration is replacing its existing endcap calorimeters with a high-granularity calorimeter (CE). The new calorimeter is a sampling calorimeter with unprecedented transverse and longitudinal readout for both electromagnetic and hadronic compartments. Due to its compactness, intrinsic time resolution, and radiation hardness, silicon has been chosen as active material for the regions exposed to higher radiation levels. The silicon sensors are fabricated as 20 cm (8”) wide hexagonal wafers and are segmented into several hundred pads which are read out individually. As part of the sensor qualification strategy, 8” sensor irradiation with neutrons has been conducted at the Rhode Island Nuclear Science Center (RINSC) and followed by their electrical characterisation in 2020-21. The completion of this important milestone in the CE's R&D program is documented in this paper and it provides detailed account of the associated infrastructure and procedures. The results on the electrical properties of the irradiated CE silicon sensors are presented.

Extracting clean low-energy spectra from silicon strip detector telescopes around punch through energies

The response of detector telescopes becomes complex around their relevant punch through energies: For some deposited energies the corresponding particle kinetic energies cannot be uniquely assigned, and these spurious energy regions can span several hundreds of keV if the telescopes are employed in close geometry. We present methods for producing clean low-energy spectra of light ions from detector telescopes consisting of thin double-sided silicon strip detectors (DSSSDs) backed by thick silicon pad detectors. By following these methods, the spectra of several such detector telescopes can be combined to span the entire relevant particle energy spectrum, above as well as below the punch through thresholds of the individual telescopes. The total energy spectrum resulting from the combination of all telescope spectra thus encompass the entire particle energy distribution in conjunction with the energy-dependent, setup-specific solid angle coverage. Energy spectra of beta-delayed proton emission from 21Mg are used to illustrate the methods.

Remote Monitoring System of Dynamic Compression Bracing to Correct Pectus Carinatum.

Pectus carinatum (PC) is a chest deformity caused by disproportionate growth of the costal cartilages compared with the bony thoracic skeleton, pulling the sternum forwards and leading to its protrusion. Currently, the most common non-invasive treatment is external compressive bracing, by means of an orthosis. While this treatment is widely adopted, the correct magnitude of applied compressive forces remains unknown, leading to suboptimal results. Moreover, the current orthoses are not suitable to monitor the treatment. The purpose of this study is to design a force measuring system that could be directly embedded into an existing PC orthosis without relevant modifications in its construction. For that, inspired by the currently commercially available products where a solid silicone pad is used, three concepts for silicone-based sensors, two capacitive and one magnetic type, are presented and compared. Additionally, a concept of a full pipeline to capture and store the sensor data was researched. Compression tests were conducted on a calibration machine, with forces ranging from 0 N to 300 N. Local evaluation of sensors' response in different regions was also performed. The three sensors were tested and then compared with the results of a solid silicon pad. One of the capacitive sensors presented an identical response to the solid silicon while the other two either presented poor repeatability or were too stiff, raising concerns for patient comfort. Overall, the proposed system demonstrated its potential to measure and monitor orthosis's applied forces, corroborating its potential for clinical practice.

Prototype electronics for the silicon pad layers of the future Forward Calorimeter (FoCal) of the ALICE experiment at the LHC

A Forward Calorimeter (FoCal) has been proposed as part of the ALICE upgrades for data taking from 2029 onwards. The FoCal will feature a sampling electromagnetic calorimeter segmented into 110 towers supplemented by a hadron calorimeter. The electromagnetic calorimeter will be composed of 20 passive layers of tungsten absorber interleaved with 18 active layers of low-granularity silicon pad sensors and two layers of high-granularity pixel detectors. Each pad layer will be read out by 110 silicon pad sensors of 72 channels, amounting to a total of 1980 sensors.This paper describes, from front-end to back-end, the electronics developed to instrument a towerprototype composed of 18 silicon pad sensors as well as a design proposal for the full-detectorreadout system.

Design and performance optimisation of the Hexaboards for CMS HGCAL silicon sensor readout electronics

A new high-granularity endcap calorimeter, HGCAL, is foreseen to be installed later this decade in the CMS experiment. We present the design and performance of the Hexaboard, a complex hexagonal multi-layer PCB equipped with multiple HGCROC ASICs to read out the signals from silicon pads with low noise and large dynamic range. The Hexaboards are glued to silicon sensors and connect to their pads via wire bonds through holes in the PCBs. The Hexaboard also connects to mezzanine boards for powering, trigger and data concentration and transfer. More than ten variants of the Hexaboard are required to cover the circular fiducial area of the CMS endcaps. Detailed performance measurements, and comparative PCB simulations using Ansys SIwave, are presented.

Abstract OT1-18-01: COMPARATIVE ANALYSIS BETWEEN ACUPUNCTURE AND EXERCISE IN IMPROVING DERMAL SENSITIVITY DURING PACLITAXEL-CONTAINING CHEMOTHERAPY: A RANDOMIZED CLINICAL TRIAL

Abstract OBJECTIVE: To compare skin sensitivity in patients diagnosed with breast cancer undergoing cycles of chemotherapy with taxanes, applied three different techniques, acupuncture needles, acupuncture with silicon tablets (Stiper) and kinesiotherapy. DESIGN: Randomized, controlled, open, parallel clinical trial. Inclusion criteria: women undergoing chemotherapy with taxanes from the 1st cycle onwards both neoadjuvant and adjuvant with stages I to III. Excluded were women with pre-existing diseases such as cancer in locoregional or distant activity, previous joint pain, rheumatologic diseases, and not undergoing chemotherapy containing Anthracyclines and/or Cisplatin, and those who had acupuncture in another service in the last three. METHODS: This study was carried out at the Oncomastology, Outpatient Clinic of the Mastology Discipline of the Gynecology Department of the Federal University of São Paulo (UNIFESP). 102 patients diagnosed with breast cancer. Excluded 39 patients,63 volunteers were selected and randomized, allocated to three groups (Group S:Stiper n=26, Group A Acupuncture n=18: and Group C: Kinesiotherapy n=19) to undergo treatment once a week for ten consecutive weeks. Signed the Informed Consent Form and agreed to participate in the project (ICF). INTERVENTION: Division of the groups, GS - non-invasive acupuncture technique (silicon pads covered with acrylic blanket) are used for stimulation of acupuncture points on the meridians. GA: acupuncture applied the technique with sterile, disposable systemic needles, (measuring 0.25mm x 30mm) for stimulation of the acupuncture points on the meridians. GC Kinesiotherapy, a physiotherapy technique consisting of upper and lower limb exercises and lower limb proprioception training and sensitivity improvement with vibration. GS, GA, performed acupuncture on the acupoints (B11Dazhu, SI14 Jianwaishu, CV12 Zhongwan, GB34 Yanglingquan, SP6 Sanyinjiao, LR3 Taichong), frequency of 1 time per week, for 10 consecutive weeks, duration of 30 minutes per session. To evaluate Sensitivity, the stesiometer was used, consisting of microfilaments thickness and the force (in grams) needed to bend the filaments, the colors and values are: green (0.05 g), blue (0.2 g), violet (2.0 g), dark red (4.0 g), orange (10.0 g) and magenta red (300 g).The evaluation of quality of life FACT/GOG-Ntx before and after treatment. RESULTS: The qualitative demographic characteristics of patients at the chemotherapy. Neoadjuvant Chemotherapy was predominantly in the three groups: GS(88.5%), GA(83.3%)and GC(89.5%), p=0.83. Cancer type CINE (Non-special Invasive Carcinoma), GS(92.6%), GA (93.8%) and GC (94.4%), p= 0.58. Diabetes Melittus GS(84.6%), GA(77.8%) and GC(79.8%), p=0.82 and Systemic Hypertension GS(72%), GA(72.2%) and GC(52.6%), p=0, 32. The C6D upper limb skin sensitivity assessment (p &amp;lt; 0.04 intergroup GS, GA and GC). T1D (p &amp;lt; 0.03 intergroup GS, GA and GC), corresponds to the forearm region. FACT/GOG-Ntx quality of life questionnaire in the domains (PWB, FWB and TaxS), Taxane Trial Outcome Index (TOI) comparing 1st session with 10th session p&amp;lt; 0.02, TaxS (Evaluates Symptoms of Chemotherapy Induced Peripheral Neuropathy) comparing 1st session with 10th session p&amp;lt; 0.03. Taxane total score) comparing 1st session with 10th session, p&amp;lt; 0.03. CONCLUSION: The C6 right hand and T1 right forearm sensitivity changes showed improvement in skin sensitivity after the intragroup intervention. FACT/GOG-Ntx questionnaire showed worsening of symptoms, physical, functional and peripheral neuropathy symptoms induced by chemotherapy compared to before and after. The cutaneous sensitivity of hands and feet remained stable and improved in the upper limbs, but chemotherapy had a negative impact on the quality of life, requiring further studies to evaluate the neuropathy of these patients. Keywords: Acupuncture, Chemotherapy, Quality of Life, Integrative and Complementary Practices.Table 1. Characteristics of skin sensitivity between groupsTable 1. Characteristics of skin sensitivity between groups Citation Format: ROBERTA P. COSTA LUZ, Carmen S. Alliz, Samantha K. Lopes de Almeida Rizzi, Cinira Haddad, Christiano Bittencourt Machado, Afonso Nazário, Gil Facina. COMPARATIVE ANALYSIS BETWEEN ACUPUNCTURE AND EXERCISE IN IMPROVING DERMAL SENSITIVITY DURING PACLITAXEL-CONTAINING CHEMOTHERAPY: A RANDOMIZED CLINICAL TRIAL [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr OT1-18-01.

TCAD simulation of the mixed irradiated n-MCz Si detector: Impact on space charges, electric field distribution

In the mixed irradiations at HL-LHC, n- MCz Si as a detector material is reported as a prime applicant. To study the non-homogeneous distribution of space charges and electric field distribution in mixed irradiated p+n MCz silicon pad detectors, four-level numerical modeling of mixed irradiation induced deep traps using microscopic parameters obtained from experimental measurements were implemented in Synopsys T-CAD. These advanced damage model parameters were sufficiently tuned to reproduce the experimental data’s on the full depletion voltage and leakage current at 293K. In this paper, the influence of effective introduction rate of shallower donor deep trap E30 K has been determined using SRH theory calculations for experimental effective doping concentration f and the behavior of space charges and electric field distribution in the presence of deep traps are thoroughly investigated.

Defect characterization studies on irradiated boron-doped silicon pad diodes and Low Gain Avalanche Detectors

High-energy physics detectors with internal charge multiplication, like Low Gain Avalanche Detectors (LGADs), that will be used for fast timing in the High Luminosity LHC experiments, have to exhibit a significant radiation tolerance. In this context, the impact of radiation on the highly boron-doped gain layer is of particular interest, since due to the so-called Acceptor Removal Effect (ARE) a radiation-induced deactivation of active boron dopants takes place, that is causing a progressive loss in the gain with increasing irradiation level. In this paper we present defect-spectroscopy measurements (Deep-Level Transient Spectroscopy and Thermally Stimulated Current technique) on neutron, proton and electron irradiated p-type silicon pad diodes of different resistivity as well as LGADs neutron irradiated at fluences up to 1×1015 neq/cm2. We show that compared to silicon pad diodes the determination of LGAD defect introduction rates is less straightforward as they are strongly influenced by the impact of the gain layer. The measured gain layer capacitance has a strong frequency and temperature dependence which makes DLTS measurements challenging to perform with results difficult to interpret. With the TSC technique the defects formed in the LGADs are nicely observed and can be compared to the defects formed in the silicon pad diodes. However, the exact assignment of defects to the gain layer or bulk region remains challenging and the charge amplification effect of the LGADs impacts the exact determination of defect concentrations. We also demonstrate that, depending on the TSC measurement conditions, defect induced internal electric fields are built up in the irradiated LGADs which impact the signal current.

RF and linearity distortion performance estimation of dopingless symmetric tunnel FET (DLSTFET)

ABSTRACT This work eradicates the issue of area penalty in logic designing due to unidirectional flow of current in conventional TFET. The dopingless symmetric tunnel FET (DL-STFET) device structure also has immunity towards random dopant fluctuations (RDFs) and trap-assisted tunnelling along with easy fabrication and a lower thermal budget. The device structure has a better drive current and subthreshold swing (SS). Furthermore, the sensitivity of the device with respect to the device dimension variation such as channel/gate length, body thickness and silicon pad thickness has also been studied on device dc, analog/RF and linearity parameters. The device dc parameters are immune towards the device dimensional variations, whereas the analog/RF and linearity parameters are sensitive to device dimension variation. The analog/RF parameters such as , , , , GBW, TGF and TFP have been studied. Furthermore, the linearity parameters such as , , , , and have also been analyzed here. This study provides the direction for designing DL-STFET for better analog/RF performance with least linearity distortions.

Can the electric field in radiation-damaged silicon pad diodes be determined by admittance and current measurements?

A method is proposed for determining the electric field in highly-irradiated silicon pad diodes using admittance-frequency (Y−f), and current measurements (I). The method is applied to Y−f and I data from square n+p diodes of 25 mm2 area irradiated by 24 GeV/c protons to four 1 MeV neutron equivalent fluences between 3×1015 cm−2 and 13×1015 cm−2. The measurement conditions were: Reverse voltages between 1 V and 1000 V, frequencies between 100 Hz and 2 MHz and temperatures of −20 °C and −30 °C. The position dependence of the electric field is parameterised by a linear dependence at the two sides of the diode, and a constant in the centre. The parameters as a function of voltage, temperature and irradiation fluence are determined by fits of the model to the data. For voltages below about 300 V all data are well described by the model, and the results for the electric field agrees with expectations: Depleted high-field regions towards the two faces and a constant low electric field in the centre, with values which agrees with the field in an ohmic resistor with approximately the intrinsic resistivity of silicon. For conditions at which the low field region disappears and the diode is fully depleted, the method fails. This happens around 300 V for the lowest irradiation fluence at −30 °C, and at higher voltages for higher fluences and lower temperatures. In the conclusions the successes and problems of the method are discussed.

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.

Investigation of the use of silicone pads to reduce the effects on the human face of classical face masks used to prevent from COVID-19 and other infections

Viruses spreads very quickly and has a fatal risk in people with chronic disease. As the virus vaccine and medications to be used for treatment are not fully developed, alternative ways to protect it from the virus are being investigated. In this study, the effects of a classical face mask on human face were investigated and computer-aided analyses were performed. Three-dimensional model of the classical face mask was performed with the SolidWorks software. The analyses were performed using AnsysWorkbench Static Structural module. The load, boundary conditions and material were defined in the AnsysWorkbench. As a result of the analyses, it has been determined that classical masks influence human face. The classical masks have a negative effective in terms of irritation on the human face. The occurred stresses cause irritation on one's skin. The use of silicone pads has been shown to reduce these effects. It was proved by this study that silicon pads can be used as an alternative method to reduce these stresses. In the future, it is planned to conduct studies investigating mask materials that do not irritate the human face.

Room-temperature repeatedly processable baroplastic/boron nitride thermal management composite

A baroplastic/boron nitride composite with low-temperature repeatable processing properties, excellent thermal conductivity performance, stability and suitable hardness that can replace conventional silicon pads is prepared.

FoCal pad prototype and its test results

A new forward calorimeter (FoCal) covering 3.4 < η < 5.8 is being developed as a possible detector upgrade of the ALICE experiment at LHC . FoCal will be a unique detector with a Si+W electromagnetic calorimeter (FoCal-E) and a conventional sampling hadronic calorimeter (FoCal-H), and the installation of and data taking with FoCal are expected during the LHC Long Shutdown 3 (in 2025-2027) and Run 4 (in 2027–2029), respectively. A prototype module, called “mini-FoCal”, was built and tested in 2018. 60 silicon pad sensors were used to produce 20 layers in total with a size of 281.0 mm by 96.0 mm and a thickness of 5.5 mm. The first beam test with the mini-FoCal was carried out at the CERN PS and SPS complexes in 2018. Electromagnetic shower signals were successfully measured in addition to the MIP peak for calibration. A good signal-to-noise ratio was confirmed and the energy resolution of the mini-FoCal was estimated to be Δ E / E = 4.1% ± 0.5% for a positron beam with an energy of 150 GeV . Following the beam tests, the mini-FoCal was temporarily placed in the ALICE cavern to study its performance under realistic experimental conditions over one month, and preliminary results are presented.

A Novel Self-Aligned Dopingless Symmetric Tunnel Field Effect Transistor (DL-STFET): A Process Variations Tolerant Design

This work reports a novel device structure, dopingless heterojunction symmetric tunnel field effect transistor (DL-STFET), based on the work-function engineering. For realizing dopingless P+-N−-P+ structure a metal with workfunction as 4.7 eV is deployed as source as well as drain electrode. This metal results in induced P+ germanium regions for the source and drain implementation. The symmetric structure of the device obviates the inherent technical drawbacks of asymmetric P+-I-N+ TFET structure that does not support bidirectional current flow and results in area penalty in layout design. As our device structure offers bidirectional current flow across germanium source, silicon channel, and germanium drain region. This in turn makes logic designing easier and it guarantees its integration with conventional CMOS technology. To improvise the device switching behaviour silicon pad is also employed below source and drain regions. Here, using exhaustive calibrated 2D TCAD simulation analysis demonstrates sub-threshold slope (SS) approximately as 59 mV/decade. Further, as the device structure does not require physical doping it is expected to exhibit immunity towards random dopant fluctuation (RDFs) and trap assisted tunnelling (TAT). Moreover, easy fabrication flow for DL-STFET because of the absence of doping and ion implantation/annealing cuts the thermal budget for the fabrication of the device as well. This device can be a strong candidate for ultra-low power integrated circuits with 0.5 V supply voltage.

Charge collection and electrical characterization of neutron irradiated silicon pad detectors for the CMS High Granularity Calorimeter

The replacement of the existing endcap calorimeter in the Compact Muon Solenoid (CMS) detector for the high-luminosity LHC (HL-LHC), scheduled for 2027, will be a high granularity calorimeter. It will provide detailed position, energy, and timing information on electromagnetic and hadronic showers in the immense pileup of the HL-LHC. The High Granularity Calorimeter (HGCAL) will use 120-, 200-, and 300-μm-thick silicon (Si) pad sensors as the main active material and will sustain 1 MeV neutron equivalent fluences up to about 1016 neq cm−2. In order to address the performance degradation of the Si detectors caused by the intense radiation environment, irradiation campaigns of test diode samples from 8-inch and 6-inch wafers were performed in two reactors. Characterization of the electrical and charge collection properties after irradiation involved both bulk polarities for the three sensor thicknesses. Since the Si sensors will be operated at −30̂C to reduce increasing bulk leakage current with fluence, the charge collection investigation of 30 irradiated samples was carried out with the infrared-TCT setup at −30̂C. TCAD simulation results at the lower fluences are in close agreement with the experimental results and provide predictions of sensor performance for the lower fluence regions not covered by the experimental study. All investigated sensors display 60% or higher charge collection efficiency at their respective highest lifetime fluences when operated at 800 V, and display above 90% at the lowest fluence, at 600 V. The collected charge close to the fluence of 1016 neq cm−2 exceeds 1 fC at voltages beyond 800 V.

Precision timing calorimetry with the CMS HGCAL

The existing CMS endcap calorimeters will be replaced with a High Granularity Calorimeter (HGCAL) for operation at the High Luminosity (HL) LHC . Radiation hardness and excellent physics performance will be achieved by utilising silicon pad sensors and SiPM-on-scintillator tiles with high longitudinal and transverse segmentation. One of the major challenges of the HL-LHC will be the high pileup environment, with interaction vertices spread not only in position, but also in time. In order to efficiently reject particles originating from pileup, precision timing information of the order of 30 ps will be of great benefit. In order to meet such performance goals, the HGCAL will provide timing measurements for individual hits with signals above 12 fC (equivalent to 3–10 MIPs), such that clusters resulting from particles with pT > 5 GeV should have a timing resolution better than 30 ps. Given the complexity and size of the system, this poses a particular challenge to the readout electronics as well as to the calibration and reconstruction procedures. We present the challenges for the front-end electronics design, results from prototype tests in laboratory and beam environments, as well as anticipated timing performance from simulation.

Versatile systems for characterization of large-area silicon pad sensors for highly-granular calorimetry

High-granularity calorimeters utilizing silicon pad sensors as main active material are being designed for the CMS endcap calorimeter upgrade and have been proposed for the electromagnetic calorimeters at CLIC, ILC and FCC-ee. The silicon sensors in such experiments are foreseen to cover a very large area of O(1000 m2). They are typically produced from 6- or 8-inch wafers and consist of a few hundred smaller cells, each with an area of O(0.1 to 1.1 cm2). Currently the CMS endcap calorimeter upgrade is in a prototyping phase with the aim of choosing the final sensor design. Flexible systems are needed for quick sensor characterization as close as possible to operating conditions, for testing different prototypes and for quality control during mass production. The ARRAY system consists of an active switching matrix PCB with 512 input channels and a passive probe card specific for each sensor layout prototype. The probe card makes contact with each individual pad through spring-loaded pins. ARRAY is designed to measure the leakage current and capacitance per-cell for different bias voltages, keeping the entire sensor area under bias. The Hexaboard probe card follows a similar principle: readout electronics foreseen to be used in the final CMS detector are mounted on a PCB that makes contact with the sensor through spring-loaded pins. It is used to perform noise and charge collection efficiency measurements with irradiated sensors without the need for module assembly. We present the design of the ARRAY and Hexaboard systems as well as measurements performed on different CMS prototype silicon sensors. We also compare the results with alternative multi-needle setups.