Time characteristics of detectors based on silicon photomultipliers for the GlueX experiment

Silicon photomultipliers (SiPMs) are used in detectors of the GlueX experiment devoted to studying the nature of confinement. These detectors are operable at counting rates as high as 2 MHz with a time resolution (FWHM) of approximately 0.3 ns and a number of excited pixels of up to 10⁴. For SiPMs that operate under these conditions, the measured dependences of the recovery time and the time resolution are presented as functions of the number of excited pixels and the excitation frequency. Using a picosecond laser, the time resolution has been measured for an array of 4 × 4 SiPMs, which was specially developed for the experiment.     

Studying voltage recovery processes on silicon photomultipliers

Dynamics of voltage recovery processes on silicon photomultipliers is experimentally and theoretically investigated. Special features of the voltage recovery in crystals with a great number of pixels are studied. Considerations on the configuration and selection of filter-element values in the supply circuit are stated. The expression for calculating the recovery time with an arbitrary number of operated pixels, taking the total number of pixels of the silicon photomultiplier, resistance value of horizontal current spreading over p- and n-regions of the pixels, and outer-element values into account, is obtained. The analytic expressions and SPICE simulation data are compared with the experimentally measured voltages across the load.     

Development of a thermal neutron detector based on scintillating fibers and silicon photomultipliers

We propose a technique for thermal neutron detection, based on a (6)Li converter placed in front of scintillating fibers readout by means of silicon photomultipliers. Such a technique allows building cheap and compact detectors and dosimeters, thus possibly opening new perspectives in terms of granular monitoring of neutron fluxes as well as space-resolved neutron detection.     

An integrated circuit for silicon photomultipliers tubes

A two-channel integrated circuit for processing current pulses of silicon photomultiplier is based on an АБМК-1.3 analog basic array. Each channel of the integrated circuit contains a transresistance amplifier with a maximal conversion coefficient of about 5 mV/μA, regulated in a ?70 dB range, and a discriminator with a threshold changeable within ±500 mV. The circuit designs of separate stages of the integrated circuit and experimental characteristics are given.     

Heavy charged particle detectors based on high-resistivity epitaxial silicon layers

A technique for manufacturing heavy charged particle detectors based on high-resistance epitaxial silicon layers is described. The special feature of this technique is the design of a rectifying structure based on a Pd₂Si−Si heterojunction. The intrinsic resolution obtainedR _int=17 keV for α-particles of²³⁸Pu (E _α=5.49 MeV) demonstrates that it is possible to design heavy charged particle detectors based on epitaxial silicon layers with good spectrometric characteristics.     

Possibilities of using silicon photomultipliers in the scintillation technique

The use of silicon photomultipliers for reading optical information from scintillators was investigated. Measurements were taken with scintillating fibers, tiles, and high-Z scintillators. In experiments with silicon photomultipliers, it was shown that relativistic particles were detected in scintillating fibers with an efficiency of 97–98% and that there were about nine photoelectrons. When information was read out of scintillator tiles via wavelength shifting fibers, the number of photoelectrons was ～15. The energy resolution of detectors based on LSO crystals was ～25% for γ rays with energies of 500–600 keV.     

The use of silicon photomultipliers for improving the time resolution of an electromagnetic calorimeter based on lead tungstate crystals

The use of S12572 MPPC silicon photomultipliers (Hamamatsu) for improving the timing characteristics of the PHOS electromagnetic calorimeter in the ALICE experiment at CERN is described. It is shown that by introducing an additional photodetector, that is, a silicon photomultiplier, it is possible, without worsening the energy resolution, to significantly improve the time resolution of the PHOS spectrometer from the current values of 3–4 ns to 150–200 ps.     

Resistance of silicon planar detectors to X-rays

We investigated the effect of X-rays with a dose of a few kilogrey on the characteristics of silicon planarp ⁺−n-detectors. The values of noise in terms of charge and the voltage-current and voltage-capacitance characteristics were analyzed. We determined the X-ray dose, for which the noise 1/f was generated. Charge accumulation in the protective oxide was responsible for this noise and affected the volt-ampere and volt-farad detector characteristics.     

A fast current preamplifier for silicon detectors

A circuit of a fast current preamplifier for silicon detectors is designed. The main purpose of the preamplifier is to record signals from silicon detectors, which repeat the detector current shape. The preamplifier noise is 0.43 nV/Hz1/2.     

The use of capacitive charge division in silicon microstrip detectors

The structure of silicon microstrip detectors with a great number of passive strips located between the readout (active) strips is described. Owing to the use of capacitive charge division among the passive and active strips, it is possible to essentially increase the readout pitch and to reduce the number of electronic readout channels by five to ten times. Since the cost of the front-end electronics exceeds significantly that of the detectors themselves, this method allows the cost of the entire detector-electronics system to be decreased severalfold without substantial deterioration of the position resolution.     

An integrated circuit for reading out signals of silicon detectors

An integrated circuit (IC) for recording signals and studying characteristics of silicon detectors is designed and experimentally checked. The basic purpose of the IC is to use it in test setups with sources of ionizing radiation and on accelerators for studying silicon detectors of a new geometry (layout). The IC allows evaluation of the operation of the “silicon detector-readout electronics” system for relativistic particles and nuclei with a charge from Z = 1 to Z > 50. The results of designing the IC and its experimental characteristics are given.     

Experimental studies of scintillation detectors based on WLS fibers

This paper describes the design and presents the results of experimental studies of single-stage and two-stage fiber-optic light collection (FOLC) scintillation detectors based on wavelength-shifting (WLS) fibers. FOLC detectors are designed for the registration of ionizing radiation with a pulse duration of up to 20 μs. The detector design allows one to place photodetectors at a distance of up to tens of meters from the scintillator. The time resolution and sensitivity of FOLC detectors to ⁶⁰Co gamma photons were studied. Experimental studies of FOLC detectors were performed at FSUE All-Russia Research Institute of Automation (VNIIA).     

基于DSP的烧结混合料中子水分控制系统

介绍利用DSP实现烧结混合料水分控制系统的方法,该系统使用中子水分仪测量水分,利用神经网络埘难测量的参数进行在线辨识,控制烧结混合料的加水量。     

Testing a 32-channel integrated circuit for recording signals of silicon detectors

A 32-channel integrated microcircuit for microstrip silicon detectors of the ??Nuklon?? project for studying ionizing radiation in space conditions is tested. The microcircuit allows one to record signals of relativistic particles and nuclei with a charge from Z = 1 up to Z > 50 from silicon detectors. A structural diagram of the microcircuit and its main experimental characteristics are given. The power consumption does not exceed 1.5 mW/channel, and the dynamic range of recorded signals is not smaller than 100 pC.     

Radiation detectors based on gas electron multipliers (Review)

Remarkable features of gas electron multipliers (GEMs) make them attractive for numerous applications in high-energy physics, nuclear physics, astrophysics, and the medical-imaging field. This review presents the results of research and development of GEM-based radiation detectors. The operating principles of GEMs and their main characteristics, including the physics of multistage GEMs and their operation in pure noble gases, are expounded. GEM-based detectors of ionizing radiations are considered. In particular, the data on tracking detectors are briefly described, while more detailed data, including the data on two-phase avalanche detectors, are presented for detectors operated at high pressures and cryogenic temperatures. A special Section is devoted to the development of GEM-based gas photodetectors.     

Laboratory nuclear-physics methods for determining the characteristics of charged particle silicon detectors

A review is presented of “nontraditional” laboratory nuclear-physical methods for determining key parameters of charged-particle semiconductor detectors, such as the sensitive depth and the energy resolution. The methods for measuring the sensitive depth are based on the peculiarities in interactions of radiation from standard α,β, and γ sources and monochromatic neutrons with the detector materials and require that several “reference” detectors with known characteristics be available. Using the proposed methods, it is possible to preliminarily estimate the serviceability of detectors before employing them in expensive experiments, e.g., on accelerator beams.     

Timing coincidence studies with fast photomultipliers

The time response of RCA C70045D photomultipliers was studied using a subnanosecond light flasher. The tubes, which have an output rise time of approximately 0.5 ns, were used in coincidence to study the variations in the fwhm of the time spectrum over a certain dynamic range of pulse amplitudes for both leading edge and constant fraction discrimination. A comparison has also been made for the measured time resolutions with some of the other fast photomultipliers.     

A fast-neutron detector based on single-crystalline silicon

It is shown that the change of the specific electrical conductivity (SEC) of silicon single crystals in the process of their irradiation is directly proportional to the fast-neutron fluence. This is used as the basis of the principle of the neutron-flux detection. The coefficient of proportionality depends on the neutron spectrum, but does not depend on the initial SEC, which significantly simplifies detector calibration. A set of wafers with different SEC values has been manufactured using the technology silicon neutron-transmutation doping. The SEC has been measured by the four-probe method. A simple method for measuring the SEC without recourse to any special setup is proposed. The random measurement error of the fast-neutron fluence was ～10%, and the absolute one was ～37%.     

基于线型感温火灾探测器的电缆隧道火灾实验

研究了线型感温火灾探测器应用于电缆隧道场所电缆火灾早期探测的工程适用性.以电缆隧道为应用环境,基于现有的线型感温火灾元件:感温电缆、光纤拉曼感温探测器和光纤光栅感温探测器,建立了实验平台,设定了不同火灾的实验场景,记录了火灾模拟试验中的温度变化和探测器响应时间.实验显示,对于初起无明火的小规模火灾,其热辐射量小,除了与其直接接触的感温火灾探测器能做出报警响应外,其余非接触式的探测器均无法响应.对大规模火灾,光纤拉曼感温探测器和光纤光栅感温探测器的报警反应时间均在30 s左右,热电偶记录的火灾发生上方60 s以内的温度都在35℃以下,而±3 m内的温升都超过5℃/min.根据3种探测器的技术特点,分析了典型线型感温火灾探测器应用于电缆隧道场所火灾早期探测的工程适用性,为规范编写《火灾报警设计规范》的相关条款提供了技术支持.