Effect of multiple coulomb scattering on the beam tests of silicon pixel detectors

In the research and development of new silicon pixel detectors,a collimated monoenergetic charged-particle test beam equipped with a high-resolution pixel-beam telescope is crucial for prototype verification and performance evaluation.When the beam energy is low,the effect of multiple Coulomb scattering on the measured resolution of the Device Under Test(DUT)must be considered to accurately evaluate the performance of the pixel chips and detectors.This study aimed to investigate the effect of multiple Coulomb scattering on the measured resolution,particularly at low beam energies.Simulations were conducted using Allpix^(2) to study the effects of multiple Coulomb scattering under different beam energies,material budgets,and telescope layouts.The simulations also provided the minimum energy at which the effect of multiple Coulomb scattering could be ignored.Compared with the results of a five-layer detector system tested with an electron beam at DESY,the simulation results were consistent with the beam test results,confirming the reliability of the simulations.

Hi'CT:a pixel sensor-based device for ion tomography

Carbon ions,commonly referred to as particle therapy,have become increasingly popular in the last decade.Accurately predicting the range of ions in tissues is important for the precise delivery of doses in heavy-ion radiotherapy.Range uncertainty is currently the largest contributor to dose uncertainty in normal tissues,leading to the use of safety margins in treatment planning.One potential method is the direct relative stopping measurement(RSP)with ions.Heavy-ion CT(Hi′CT),a compact segmented full digital tomography detector using monolithic active pixel sensors,was designed and evaluated using a 430 MeV/u high-energy carbon ion pencil beam in Geant4.The precise position of the individual carbon ion track can be recorded and reconstructed using a 30μm×30μm small pixel pitch size.Two types of customized image reconstruction algorithms were developed,and their performances were evaluated using three different modules of CAT-PHAN 600-series phantoms.The RSP measurement accuracy of the tracking algorithm for different types of materials in the CTP404 module was less than 1%.In terms of spatial resolution,the tracking algorithm could achieve a 20%modulation transfer function normalization value of CTP528 imaging results at 5 lp/cm,which is significantly better than that of the fast imaging algorithm(3 lp/cm).The density resolution obtained using the tracking algorithm of the customized CTP515 was approximately 10.5%.In conclusion,a compact digital Hi'CT system was designed,and its nominal performance was evaluated in a simulation.The RSP resolution and image quality provide potential feasibility for scanning most parts of an adult body or pediatric patient,particularly for head and neck tumor treatment.

Advances in nuclear detection and readout techniques

“A Craftsman Must Sharpen His Tools to Do His Job,”said Confucius.Nuclear detection and readout techniques are the foundation of particle physics,nuclear physics,and particle astrophysics to reveal the nature of the universe.Also,they are being increasingly used in other disciplines like nuclear power generation,life sciences,environmental sciences,medical sciences,etc.The article reviews the short history,recent development,and trend of nuclear detection and readout techniques,covering Semiconductor Detector,Gaseous Detector,Scintillation Detector,Cherenkov Detector,Transition Radiation Detector,and Readout Techniques.By explaining the principle and using examples,we hope to help the interested reader underst and this research field and bring exciting information to the community.

A method for correcting characteristic X-ray net peak count from drifted shadow peak

To correct spectral peak drift and obtain more reliable net counts,this study proposes a long short-term memory(LSTM)model fused with a convolutional neural network(CNN)to accurately estimate the relevant parameters of a nuclear pulse signal by learning of samples.A predefined mathematical model was used to train the CNN-LSTM model and generate a dataset composed of distorted pulse sequences.The trained model was validated using simulated pulses.The relative errors in the amplitude estimation of pulse sequences with different degrees of distortion were obtained using triangular shaping,CNN-LSTM,and LSTM models.As a result,for severely distorted pulses,the relative error of the CNN-LSTM model in estimating the pulse parameters was reduced by 14.35%compared with that of the triangular shaping algorithm.For slightly distorted pulses,the relative error of the CNN-LSTM model was reduced by 0.33%compared with that of the triangular shaping algorithm.The model was then evaluated considering two performance indicators,the correction ratio and the efficiency ratio,which represent the proportion of the increase in peak area of the two characteristic peak regions of interest(ROIs)to the peak area of the corrected characteristic peak ROI and the proportion of the increase in peak area of the two characteristic peak ROIs to the peak areas of the two shadow peak ROI,respectively.Ten measurement results of the iron ore samples indicate that approximately 86.27%of the decreased peak area of the shadow peak ROI was corrected to the characteristic peak ROI,and the proportion of the corrected peak area to the peak area of the characteristic peak ROI was approximately 1.72%.The proposed CNN-LSTM model can be applied to X-ray energy spectrum correction,which is of great significance for X-ray spectroscopy and elemental content analyses.

CSHINE for studies of HBT correlation in heavy ion reactions

The compact spectrometer for heavy ion experiment(CSHINE)is under construction for the study of isospin chronology via the Hanbury Brown–Twiss(HBT)particle correlation function and the nuclear equation of state of asymmetrical nuclear matter.The CSHINE consists of silicon strip detector(SSD)telescopes and large-area parallel-plate avalanche counters,which measure the light charged particles and fission fragments,respectively.In phase I,two SSD telescopes were used to observe 30 MeV/u 40Ar?197Au reactions.The results presented here demonstrate that hydrogen and helium were observed with high isotopic resolution,and the HBT correlation functions of light charged particles could be constructed from the obtained data.

New Soft x-ray PHA Diagnostic in the HT-7 Tokamak

A soft x-ray Pulse Height Analysis (PHA) diagnostic with the recently introduced Silicon Drift Detector (SDD) and a new MCA system has been installed in HT-7 for the measurements of electron temperature. With the SDD detector, the x-ray emission can be detected in the energy range from 1 keV up to 20 keV. The extremely low anode capacity of SDD allows very high counting rates of x-ray above 200 kHz and short shaping times below 0.25 μs to be measurede. In routine operation a counting rate of 120 kHz has been normally obtained with an energy resolution of better than 180 eV at 5.9 keV. The assembly is equipped with six SDD detectors measuring the soft x-ray emission integrated along six chords of the upper half plasma cross section. The preliminary results from the new soft x-ray PHA diagnostic are also presented in this paper.

Soft X-ray PHA Diagnostic for the Electron Ternperature Measurements on EAST

Two soft X-ray pulse height analysis （PHA） systems, based on silicon drift detec- tor （SDD）, were established on the experimental advanced superconducting tokamak （EAST） to measure spectrum of soft X-ray emission. In this paper, the soft X-ray PHA systems on EAST are introduced and some experimental results of electron temperature in EAST obtained from the soft X-ray PHA diagnostic are presented.

Simulation of silicon strip detector for space-based cosmic ray experiments with Allpix^(2)

Purpose Silicon strip detectors are widely applied in space-based cosmic ray experiments and most of the silicon strip detectors deploy an analytical method for its digitization.However,the analytical method simplifies the physical process of propagation of electrons/holes generated inside the silicon detector by particles that pass through the detector.In order to simulate silicon strip detectors with different configurations comprehensively,the Allpix^(2),an open-source software,is used to study those processes.Methods When particle passes through the silicon detector,energy is deposited based on Geant4 simulation,and electron-hole pairs are created due to the deposited energy.The Allpix^(2)simulation method and the analytical method are both used to calculate or simulate the diffusion and drift processes that electron-hole pairs propagate inside the silicon detector under internal electric field,and the number of electrons/holes accumulated at implanted strips are counted.Results and conclusion The number of electrons/holes accumulated along the implanted strips are compared between the Allpix^(2)simulation method and analytical method for different incident angles and different incident positions,they are found to be in good agreement for proton particles,while there are discrepancies for carbon and silicon particles.The Allpix^(2)software may be an important tool for the study of response of silicon strip detectors in space.The charge resolution of single implanted strip predicted by Allpix^(2)simulation method is about 4.7%for proton,3.8%for carbon and 1.6%for silicon particles for an incident angle of 45◦.

Hybrid silicon modulators

A number of active elements have been demonstrated using the hybrid silicon evanescent platform, including lasers, amplifiers, and detectors. In this letter, two types of hybrid silicon modulators, flflfilling the building blocks in optical communication on this platform, are presented. A hybrid silicon electroabsorp- tion modulator, suitable for high speed interconnects, with 10-dB extinction ratio at -5 V and 16-GHz modulation bandwidth is demonstrated. In addition, a hybrid silicon Mach-Zehnder modulator utilizing carrier depletion in multiple quantum wells is proved with 2 V.mm voltage-length product, 150-nm optical bandwidth, and a large signal modulation up to 10 Gb/s.

Tailoring the spectral response of add/drop single and multiple resonators in silicon-on-insulator

Channel dropping waveguide filters based on single and technology are of great interest due to their compactness multiple resonators in silicon-on-insulator （SOI） and high wavelength selectivity, which is a desirable feature for photonic modulators, detectors, and other optically integrated components in telecommu- nication systems, in particular for wavelength division multiplexing （WDM） systems. Particular advantage of these filters is that they are capable of producing relatively large free spectral range （FSR） as well as narrow 3-dB bandwidth of the filter resonances. Herein we sibility of designing mono-mode and （nearly） polarization with the FSR in excess of 30 nm. report experimental results and discuss the posindependent SOI ring and racetrack resonators

Design and performance study of the LEPD silicon tracker onboard the CSES satellite

The low energy particle detector （LEPD） is one of the main payloads onboard the China seismic electromagnetic satellite （CSES）. The detector is designed to ascertain space electrons （0.1–10 MeV） and protons （2–50 MeV）. It has the capability of identifying the electrons and protons, to measure the energy spectrum and the incident angle of the particles. The LEPD is made up of a silicon tracker system, a CsI （Tl） mini-calorimeter, an anti-coincidence system made by plastic scintillator, as well as electronics and a data acquisition system （DAQ）. The tracker is also a kind of E-E telescope; it consists of two layers of double-sided silicon strip detectors （DSSD）. The signals emerging from the silicon tracker can be read out by two pieces of application specific integrated circuit （ASIC）, which also can generate an event trigger for the LEPD. The functions of the DSSD system in the LEPD for charged particles were tested by 241Am @5.486 MeV α particles. The results show that the DSSD system works well, and has high performance to detect charged particles and measure the position of incident particles.

Development of large-area quadrant silicon detector for charged particles

The quadrant silicon detector, a kind of passivated implanted planar silicon detector with quadrant structure on the junction side, gained its wide application in charged particle detection. In this paper, the manufacturing procedure, performance test and results of the quadrant silicon detector developed recently at the China Institute of Atomic Energy are presented. The detector is about 300 μm thick with a 48 mm×48 mm active area.The leakage current under the full depletion bias voltage of-16 V is about 2.5 n A, and the rise time is better than160 ns. The energy resolution for a 5.157 Me V α-particle is around the level of 1%. Charge sharing effects between the neighboring quads, leading to complicated correlations between two quads, were observed when α particles illuminated on the junction side. It is explained as a result of distortion of the electric field of the inter-quad region.Such an event is only about 0.6% of all events and can be neglected in an actual application.

A prototype silicon detector system for space cosmic-ray charge measurement

A readout electronics system used for space cosmic-ray charge measurement for multi-channel silicon detectors is introduced in this paper, including performance measurements. A 64-channel charge sensitive ASIC （VA140） from the IDEAS company is used. With its features of low power consumption, low noise, large dynamic range, and high integration, it can be used in future particle detecting experiments based on silicon detectors.

Design of the readout electronics for the DAMPE Silicon Tracker detector

The Silicon Tracker （STK） is one of the detectors of the DAMPE satellite used to measure the incidence direction of high energy cosmic rays. It consists of 6 X-Y double layers of silicon micro-strip detectors with 73728 readout channels. It is a great challenge to read out the channels and process the huge volume of data in the harsh environment of space. 1152 Application Specific Integrated Circuits （ASIC） and 384 ADCs are used to read out the detector channels. 192 Tracker Front-end Hybrid （TFH） modules and 8 identical Tracker Readout Board （TRB） modules are designed to control and digitalize the front signals. In this paper, the design of the readout electronics for the STK and its performance are presented in detail.

DAMPE silicon tracker on-board data compression algorithm

The Dark Matter Particle Explorer（DAMPE） is an upcoming scientific satellite mission for high energy gamma-ray, electron and cosmic ray detection. The silicon tracker（STK） is a subdetector of the DAMPE payload.It has excellent position resolution（readout pitch of 242 μm）, and measures the incident direction of particles as well as charge. The STK consists of 12 layers of Silicon Micro-strip Detector（SMD）, equivalent to a total silicon area of6.5 m2. The total number of readout channels of the STK is 73728, which leads to a huge amount of raw data to be processed. In this paper, we focus on the on-board data compression algorithm and procedure in the STK, and show the results of initial verification by cosmic-ray measurements.

An Implantation and Detection System for Spectroscopy of 22,24Si

A new decay detection system with high detection efficiency and low detection threshold has been developed for charged-particle decay studies, including β-delayed proton, α decay or direct proton emission from proton-rich nuclei. The detection system was tested by using the β-delayed proton emitter ^(24)Si and was commissioned in the decay study of ^(22)Si produced by projectile fragmentation at the First Radioactive Ion Beam Line in Lanzhou. Under a continuous-beam mode, the isotopes of interest were implanted into two double-sided silicon strip detectors, where the subsequent decays were measured and correlated to the preceding implantations by using position and time information. The system allows to measure protons with energies down to about 200 ke V without obvious β background in the proton spectrum. Further application of the detection system can be extended to the measurements of β-delayed proton decay and the direct proton emission of other exotic proton-rich nuclei.

Mechanical design of an ultra-light vertex detector prototype for CEPC

Background The Circular Electron Positron Collider(CEPC)is a large international scientific facility proposed to study the Higgs boson in great detail.It requires state-of-the-art detectors,including extremely precise vertexing and tracking devices,such as a silicon vertex detector.Purpose Silicon vertex detector with the precision required by the CEPC has never been built before and needs extensive research and development.This paper describes the mechanical design of a vertex detector prototype being built to explore the required technologies and the major challenges.Methods The exceptional high spatial resolution of the CEPC vertex detector is achievable only with a detector of extremely low mass to limit particle scattering.This paper proposes a mechanical design for the vertex detector prototype,highlighting the choice of low-mass materials,the analysis of support structures,the solution of detector cooling issues,and the drafts of procedures for detector assembly.Results The ultra-light support of the ladder(a structural unit of the CEPC vertex detector prototype),which is mainly made of carbon fiber reinforced polymer composite,has been designed.The fabrication process has also been verified.Global supporting and cooling method of the vertex detector prototype has been designed and chosen with results from finite element analysis and computational fluid dynamics simulations.Complete assembly and installation schemes for the prototype have been developed,and the respective tooling has also been designed.The performance of the vertex detector prototype,using this low-mass mechanical structure,was demonstrated with fast simulation to closely meet the CEPC physics requirement.

Test of a fine pitch SOI pixel detector with laser beam

A silicon pixel detector with fine pitch size of 19 μm × 19 μm, developed based on SOI （silicon-on- insulator） technology, was tested under the illumination of infrared laser pulses. As an alternative method for particle beam tests, the laser pulses were tuned to very short duration and small transverse profile to sinmlate the tracks of MIPs （minimum ionization particles） in silicon. Hit cluster sizes were measured with focused laser pulses propagating through the SOI detector perpendicular to its surface and most of the induced charge was found to be collected inside the seed pixel. For the first time, the signal amplitude as a function of the applied bias voltage was measured for this SOI detector, deepening understanding of its depletion characteristics.