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.     

Radiation damage in silicon detectors

A review is presented of the effects of radiation damage on silicon detectors, which are being considered for high energy physics applications. The main degradation in performance is an increase in leakage current, which can be well characterized by an empirical damage constant for many radiations. A summary of data on damage constants is given. A brief discussion of annealing effects in terms of band gap level changes is included.     

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.     

Energy resolution of silicon surface-barrier detectors for oxygen and sulphur ions

A group of 9 silicon surface-barrier detectors, 4 manufactured by ORTEC and 5 fabricated by the first author and his students. has been tested for their energy resolutions with oxygen ions of 36.750 and 50 MeV energy and sulphur ions of 51.086 MeV energy from the University of Pittsburgh Van de Graaff accelerator. Six of the detectors had previously been tested with oxygen ions of 25 and 50 MeV energy at Pittsburgh, and those results are compared with the present ones. It is now possible to conclude that the energy resolution of the best detectors is independent of oxygen ion energy between 36.750 and 50 MeV and is about 100 keV (fwhm). When tested with sulphur ions, 4 of the detectors showed anomalous effects, including peaks and smudges both below and above the main peak. Some of these could be eliminated by varying the reverse bias voltage across the detector, others could not. In particular, the ORTEC detector 40, used in the previous work as the standard detector presently available, did not show a single peak at any bias. It is an excellent detector for oxygen ions, but is not useful for sulphur ions. The energy resolution of the best detectors for 51.086 MeV sulphur ions is under 300 keV (fwhm).     

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).     

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.     

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.     

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。     

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.