On the laser calibration of charged particle detectors

Problems coupled with laser reference systems of gas charged particle detectors (drift, time-projection, and streamer chambers) are considered: the physical principles of formation of laser tracks, the methods used to create thin laser beams, the characteristics of ultraviolet nitrogen lasers, etc. Examples of existing and currently being designed laser systems intended for spatial and energy calibration of the detectors are presented.     

Calibration of the neutron detectors for the cluster fusion experiment on the Texas Petawatt Laser

Three types of neutron detectors (plastic scintillation detectors, indium activation detectors, and CR-39 track detectors) were calibrated for the measurement of 2.45 MeV DD fusion neutron yields from the deuterium cluster fusion experiment on the Texas Petawatt Laser. A Cf-252 neutron source and 2.45 MeV fusion neutrons generated from laser-cluster interaction were used as neutron sources. The scintillation detectors were calibrated such that they can detect up to 10(8) DD fusion neutrons per shot in current mode under high electromagnetic pulse environments. Indium activation detectors successfully measured neutron yields as low as 10(4) per shot and up to 10(11) neutrons. The use of a Cf-252 neutron source allowed cross calibration of CR-39 and indium activation detectors at high neutron yields (～10(11)). The CR-39 detectors provided consistent measurements of the total neutron yield of Cf-252 when a modified detection efficiency of 4.6×10(-4) was used. The combined use of all three detectors allowed for a detection range of 10(4) to 10(11) neutrons per shot.     

Absolute calibration of X-ray optical elements and detectors at a wavelength of 46.9 nm

The results are presented of the absolute calibration of X-ray optical elements (diffraction gratings and Sc/Si multilayers) and detectors (an УΦ-4 photographic film and a vacuum X-ray diode) used in diagnostic devices to study generation of X-ray laser radiation in an argon plasma of a capillary discharge (λ = 46.9 nm). The measurements have been performed at the soft X-ray and vacuum UV station of the VEPP-4 storage ring at the Siberian International Center of Synchrotron Radiation. An absolutely calibrated AXUV 100G photodiode has been used as a reference detector. The relative error of calibration is 10%. The measured reflectances of the multilayer mirrors and gratings are in good agreement (within the limits of errors) with the results of their calibration at the RKK-1-100 X-ray calibration facility.     

Calibration of detectors of ionizing emissions by means of a subnanosecond runaway electron beam generated by discharge in open atmosphere at high overvoltages

The electric discharge in air at atmospheric pressure under the conditions of multiple overvoltages generates an electron beam of subnanosecond duration. By means of measurements of the resolution time of registration lines including different detectors of ionizing emissions, efficiency is demonstrated of the beam application for calibration of the detectors with the subnanosecond resolution. The basic advantages of such a way of calibration is the absence of the evacuated accelerating tube, small dimensions of the source, and the big resource.     

Study of saturation of CR39 nuclear track detectors at high ion fluence and of associated artifact patterns

The occurrence of saturation in CR39 solid state nuclear track detectors has been systematically studied as a function of the incident ion (alpha particles and laser-accelerated protons) fluence and the etching time. When overexposed (i.e., for fluences above approximately 10(8) particles/cm(2)) and/or overetched, the CR39 detectors enter a saturated regime where direct track counting is not possible anymore. In this regime, optical measurements of saturated CR39 detectors become unreliable as well, since the optical response of the saturated detectors with respect to the ion fluence is highly nonlinear. This nonlinear optical response is likely due to scattering from the surface of irregular clumping patterns which have a diameter approximately 20 microm, i.e., ten times larger than the diameter of individual tracks. These patterns, which aggregate many individual tracks, are observed to develop in highly saturated regimes. For fluences typical of high energy short pulse laser experiments, saturation occurs, inducing the appearance of artifact ringlike structures. By careful microscopic analysis, these artifact ring patterns can be distinguished from the genuine rings occurring below saturation and characteristic of low energy laser accelerated proton beams.     

Measuring the performance of scanning electron microscope detectors

A simple digital method of measuring the performance of detectors in the scanning electron microscope (SEM) is described. The value derived is absolute and can therefore be used to compare both different detectors on the same instrument as well as different detectors on different instruments. The technique can be applied to secondary electron, backscattered electron, and energy-dispersive x-ray detectors. Examples are given of measurements made on a variety of commercial detectors installed on a number of current SEMs.     

Neutron detectors based on silicon photomultipliers

Neutron detectors comprising a new type of photosensors—silicon photomultipliers—coupled to a single-crystal LiI(Eu) scintillator and a ⁶LiF/ZnS(Ag) scintillation screen are described. These detectors are compact, which improves their usability. Some parameters of the detectors are presented, their sensitivity to thermal neutrons and γ rays is estimated, and their possible applications are proposed.     

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).     

Segmented high-purity germanium detectors

Segmented planar high-purity germanium detectors were developed. Segmentation of p-n junction was performed by implantation of boron (for the n-type Ge) and mechanical grooving of the Li diffusion layer (for the p-type Ge). The electric and spectrometric characteristics of each individual segment and interactions between segments were investigated. The reliability and stability of the detectors were improved by using special passivation of the crystal surfaces.     

Passivation of HPGe detectors

Protective oxide coating of p-n junctions in HPGe detectors is investigated. Owing to this coating, HPGe detectors can be used, in particular, in liquid nitrogen environment without capsulation. A simple and practically feasible method for forming the protective layer by processing detectors in methanol is described. It is shown that this layer reliably protects p-n junctions of HPGe detectors from environmental impact. The characteristics of the protective oxide film are investigated using the Raman scattering method. Original Russian Text ? Yu.B. Gurov, V.S. Karpukhin, S.V. Rozov, V.G. Sandukovsky, D. Borowicz, J. Kwiatkowska, B. Rajchel, J. Yurkowski, 2009, published in Pribory i Tekhnika Eksperimenta, 2009, No. 1, pp. 151–154.     

IR imaging using uncooled microcantilever detectors

Uncooled bimaterial microcantilever detectors were fabricated and used to obtain infrared (IR) images of objects at temperatures ranging from room temperature to a few hundred degrees C. Images were obtained using both single 50 micro m x 50 micro m microcantilever IR detectors and arrays of microcantilever detectors. Thermal radiation from the target object was imaged onto the detector and the resulting temperature change caused microcantilever bending due to the bimaterial effect. This micromechanical bending was measured using two different non-contact optical readout techniques and IR images were obtained. A smaller size (20 micro m x 20 micro m) microcantilever IR detector was also used to capture IR images of near room temperature objects.     

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.     

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.     

Energy-sensitive cryogenic detectors for high-mass biomolecule mass spectrometry

Energy-sensitive calorimetric detectors that operate at low temperatures ("cryogenic detectors") have recently been applied for the first time as ion detectors in time-of-flight mass spectrometry. Compared to conventional, ionization-based detectors, which rely on secondary electron formation or the charge created in a semiconductor, cryogenic detectors measure low-energy solid state excitations created by a particle impact. This energy sensitivity of cryogenic detectors results in several potential advantages for TOF-MS. Cryogenic detectors are expected to have near 100% efficiency even for very large, slow-moving molecules, in contrast to microchannel plates whose efficiency drops considerably at large mass. Thus, cryogenic detectors could contribute to extending the mass range accessible by TOF-MS and help improving detection limits. In addition, the energy resolution provided by cryogenic detectors can be used for charge discrimination and studies of ion fragmentation, ion-detector interaction, and internal energies of large molecular ions. Cryogenic detectors could therefore prove to be a valuable diagnostic tool in TOF-MS. Here, we give a general introduction to the cryogenic detector types most applicable to TOF-MS including those types already used in several TOF-MS experiments. We review and compare the results of these experiments, discuss practical aspects of operating cryogenic detectors in TOF-MS systems, and describe potential near future improvements of cryogenic detectors for applications in mass spectrometry.     

高效液相色谱紫外检测器性能差异的评价

紫外检测器是高效液相色谱最常用的检测器,其噪声、基线漂移等技术参数是仪器的重要性能指标。但仪器在实际使用中常因响应值的标示和单位换算发生变化而产生误差,影响到指标的可比性。本实验在尽可能保证试验条件一致的情况下,对8个不同厂家及型号的紫外检测器的噪声、响应值、不同进样浓度下的信噪比及峰形等参数进行了比较研究,提出了根据特定浓度样品溶液响应的信噪比来评价检测器灵敏度的方法。该方法具有较好的可比性和实用性。实验还表明,不同的检测器对峰形也有影响,并初步探讨了部分差异产生的原因。     

An environmental monitoring system for semiconductor detectors

Hardware and software of environmental monitoring systems for semiconductor microstrip detectors of the SCT silicon tracker is described. The work has been done at the CERN (Geneva, Switzerland) as part of the ATLAS project for the LHC accelerator.     

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.     

A readout for large arrays of microwave kinetic inductance detectors

Microwave kinetic inductance detectors (MKIDs) are superconducting detectors capable of counting single photons and measuring their energy in the UV, optical, and near-IR. MKIDs feature intrinsic frequency domain multiplexing (FDM) at microwave frequencies, allowing the construction and readout of large arrays. Due to the microwave FDM, MKIDs do not require the complex cryogenic multiplexing electronics used for similar detectors, such as transition edge sensors, but instead transfer this complexity to room temperature electronics where they present a formidable signal processing challenge. In this paper, we describe the first successful effort to build a readout for a photon counting optical/near-IR astronomical instrument, the ARray Camera for Optical to Near-infrared Spectrophotometry. This readout is based on open source hardware developed by the Collaboration for Astronomy Signal Processing and Electronics Research. Designed principally for radio telescope backends, it is flexible enough to be used for a variety of signal processing applications.     

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.     

Investigating the characteristics of scintillation detectors for the NEVOD-EAS experiment

A cluster type NEVOD-EAS setup is being constructed by the National Research Nuclear University MEPhI on the basis of the Unique Scientific Facility “Experimental Complex NEVOD”. The NEVODEAS setup is intended for the detection of extensive air showers (EASs) with energies in the region of the knee in the energy spectrum of primary cosmic rays (10¹⁵–10¹⁷ eV). The key elements of the setup are 192 particle detectors for EAS electron–photon and muon components. These detectors are composed of NE102A organic scintillators and Philips XP3462 photomultiplier tubes enclosed in pyramidal steel cases. The techniques used to investigate the characteristics of scintillator plates, photomultiplier tubes, and NEVOD-EAS detectors, as well as the results of this investigation, are discussed. All measurements have been taken using special testing facilities and the precision URAGAN muon hodoscope, with which it is possible to comprehensively investigate the nonuniformity of light collection in the detector (the dependence of the detector response on the location of the passage of a charged particle through its operating volume).