Development of multianode photomultiplier tube

We have developed a multianode photomultiplier tube (MAPMT) which has a sensitive cathode diameter of 36 mm and an anode with 88 segments. The position sensitivity of the tube was studied by using light from a LED and scintillation light from a scintillation-fiber bundle. We observed particle tracks for the first time by using a single photomultiplier tube.     

Performance of a photomultiplier tube with transmissive dynodes in a high magnetic field

The performance of a photomultiplier tube with transmissive dynodes was examined. We found that the amplification gain was higher than 10⁴ even in a magnetic field of 7.8 kG. The energy resolution for 662 keV gamma rays from ¹³⁷Cs was 12% fwhm measured using a NaI crystal at 7.8 kG. The time resolution was as good as about 200 ps at 7.8 kG for the light generated by 2 GeV pions when they passed through a 1 cm thick scintillator mounted on the tube.     

Influence of the photomultiplier tube spatial uniformity on lidar signals

Measurements of the spatial uniformity of Hamamatsu H5783-06 photosensor modules were performed by the flying spot method. The results were used to simulate the influence of the photomultiplier tube on a lidar signal. A simple method for improving the spatial uniformity is proposed.     

A new hybrid photomultiplier tube as detector for scintillating crystals

In this work, we have attentively studied the performance of a new hybrid photomultiplier tube (HPMT) as detector for photons from scintillating crystals. The HPMT is equipped with a YAP window in order to improve light collection and increase measured light response from scintillating crystals. Several measurements have been performed on BGO, LSO, CsI(Tl) and NaI(Tl) planar crystals having three different surface treatments as well as on YAP : Ce and CsI(Tl) matrices. Such crystals have been coupled to two HPMTs, one equipped with a YAP window (Y-HPMT) and the other with a conventional quartz window (Q-HPMT). Measurements on crystals coupled to the Y-HPMT have shown a consistent improvement of the light response, thanks to the presence of the YAP window. Indeed, the light response measured with the Y-HPMT was on average equal to 1.5, 2.1 and 2.6 times that obtained with the Q-HPMT for planar crystals with white painted (diffusive), fine ground and polished rear surfaces, respectively. With regards to crystal matrices, we measured a light response increase of about 1.2 times.     

气囊对光电倍增管水下内爆影响试验研究

江门中微子试验中使用的光电倍增管需要长时间承受高静水压力作用,由于光电倍增管外壳使用膨化硅玻璃制造,受自身结构微观缺陷影响不可避免的有发生碎裂的可能,并引发光电倍增管的水下内爆(Implosion),对其周围设施造成危害。在可加压密封罐中进行带有气囊的光电倍增管水下内爆试验,使用高速摄像和压力传感器记录实验过程数据。并将试验结果与无气囊条件下的光电倍增管水下内爆相关数据进行对比,探究了使用气囊进行光电倍增管水下内爆防护的可行性,为光电倍增管的水下内爆防护提供新的思路。     

Simple photomultiplier tube internal-gating method for use in subnanosecond time-resolved spectroscopy

We propose a simple photomultiplier tube (PMT) internal-gating method for use in the field of subnanosecond time-resolved spectroscopy. In the proposed method, we control two dynodes in the PMT by applying a gate signal whose pulse width is Tg. When controlling the mth and the n(> m)th dynodes, a resolution time delta t is approximately given by delta t = Tg-(n-m) tau, where tau is a transit time of a lump of secondary electrons traveling between the two dynodes in the PMT. In principle, the resolution time delta t shorter than the pulse width Tg of the gate signal can be easily obtained. From a fundamental performance test, we found that a subnanosecond resolution time delta t = 0.31 ns was obtained for the case of m = 2 and n = 5. To demonstrate the effectiveness of the proposed method, we carried out a time-resolved spectroscopic measurement of emission obtained from a white-light-emitting diode (LED) driven by a nanosecond current pulse.     

Analysis of data obtained from a frequency-multiplexed phase-modulation fluorometer using an autoregressive model

In order to derive plural values of fluorescence lifetimes simultaneously from a multi-component sample, we formulate a mathematical method for analyzing data obtained from a frequency-multiplexed phase-modulation fluorometer (FM-PMF) using an autoregressive (AR) model. Various parameter settings necessary for performing accurate data analysis based on the AR model are studied through numerical simulations. Measurement results of fluorescence lifetimes of real samples, 10 ppm quinine sulfate in 0.1 N H(2)SO(4), 10 ppm rhodamine 6G in ethanol, and their mixture with a volume ratio of 1:1, demonstrate that the proposed method works quite well.     

New Raman spectrometer using a digital micromirror device and a photomultiplier tube detector for rapid on-line industrial analysis. Part II: Choice of analytical methods

In this paper, the performances of four improved analytical methods (backward stepwise selection of peak intensities, sum of characteristic peaks of a component, moving window partial least squares, and genetic algorithms) using wavelength selection for the analysis of xylene mixtures by Raman spectroscopy are tested for further use on the new "digital micromirror device associated with a photomultiplier tube" Raman spectrometer. It is shown that the errors of prediction using only a few selected points (from 4 to 49 depending on the method) are almost the same as when using the whole spectral range (1050 points). Compared to the last two methods, the "backward stepwise selection of peak intensities" and "sum of characteristic peaks of a component" methods are robust under industrial conditions and appear to be well suited for chemical quantitative analysis with the new Raman spectrometer, which allows the measurements of the total intensity to be made simultaneously for a number of pre-selected frequencies. Results show that the errors of prediction can be near to or even lower than 2%.     

New Raman spectrometer using a digital micromirror device and a photomultiplier tube detector for rapid on-line industrial analysis. Part I: description of the prototype and preliminary results

In this paper, a prototype of a new generation of Raman spectrometers, based on the use of a monochromator, a digital micromirror device as light modulator, and a photomultiplier tube as detector of the Raman light, is described. This spectrometer, containing no moving parts, is inexpensive, robust, and very precise. New in concept, this spectrometer makes it possible to record, in addition to classical Raman spectra, the intensity at several selected points of the spectrum and/or the total intensity in several selected intervals at the same time with great accuracy, thus giving new possibilities for analytical applications. Also, the work presented demonstrates the possibilities of this very simple prototype for rapid on-line industrial analysis, with an example of quantitative analysis of binary and ternary mixtures of xylene isomers. The precision obtained is satisfactory (errors of prediction approximately 3% in 5-6 seconds per sample).     

Two-dimensional neutron detector based on a position-sensitive photomultiplier

A new type of two-dimensional neutron scintillation detector with high spatial resolution based on a position-sensitive photomultiplier has been investigated. With a ⁶Li glass scintillator a spatial resolution of 1.0 mm was measured. The integral linearity over the detection area of 55 × 45 mm² is ⩽1.5 mm. The detector homogeneity is within 10% at a discriminator level at 60% of the average peak height. The spatial resolution is expressed by a geometrical parameter which could be evaluated from light experiments and by the number of photoelectrons per neutron capture.     

A useful method to monitor outputs from a pulsed light source and its application to rate effect studies in a photomultiplier tube

In order to study short-term gain stability in a photomultiplier tube at high counting rate, we constructed an LED pulsed light source and its output monitoring system. For the monitoring system, we employed a photon counting method using a photomultiplier as a monitor photon detector. It is found that the method offers a simple way to monitor outputs from a pulsed light source and that, together with an LED light source, it provides a useful method to investigate photomultiplier's rate effects.     

Cryogenic thermoelectric thermometer using a heat tube

An original application of heat tubes is proposed for increasing the accuracy of cryogenic temperature measurement. This is achieved by supplementary action on the working end of the thermocouple, based on the tube's heat energy transmission, controlled by a magnetic field.Translated from Izmeritel'naya Tekhnika, No. 4, pp. 45–47, April, 1995.     

Manufacturing a telescopic tube screw using a hydroforming process

The telescopic tube screw, which can provide an adjustable length feature, has been widely used in many applications that allow for a secure and perfect fit. This study investigates an innovative hydroforming process for producing a telescopic tube screw with internal thread on the outer tube and outer thread on the inner tube. First, the outer tubes, with internal thread, are hydroformed. Thereafter, one hydroformed outer tube is half-sectioned and concentrically combined with the inner tube. Following this, the concentric tubes are expanded by using a hydroforming process so that external thread is formed on the inner tube. The small gap between inner and outer tubes that is created by the difference in elastic recoveries allows them to rotate about one another to ensure smooth operation of the screw and sleeve mechanism. The investigation is supported by finite element analysis to determine the optimum thread shape. The structural strength of tube screw is experimentally estimated by lateral three-point bending test. The superior structural strength of the tube screws strongly confirms the reliability and applicability of the telescopic tube screws manufactured in this study.     

Fiber optic fluorometer with dipping module

A fiber optic fluorometer with dipping module intended for use in studying the contents of phytoplankton in sea water at different depths is described. Using the device, it is possible to carry out continuous measurements under the conditions of the strongly variable illuminance of the sea. Results of measurements of the fluorescence of sea water by means of the newly developed fluorometer are presented. __________ Translated from Izmeritel’naya Tekhnika, No. 1, pp. 27–29, January, 2008.     

Comparison of two different ways of using inertance tube in a pulse tube cooler

It is well known that the pressure wave should lead the volume flow rate at the ambient end of the pulse tube for a high-efficiency operation of a pulse tube cooler. Inertance tube can provide such a phase relationship without DC flow problem. However, inertance tube is always connected with a reservoir in previous literatures. Through theoretical calculation here, inertance tube without a reservoir can also provide a rather large phase-leading effect. Thus phasor diagram is used to analyze the relationship between phase-leading requirement and the pulse tube geometry. Roughly speaking, a larger void volume of pulse tube would require a larger phase-leading effect. Comparison experiments are also done on a thermoacoustically-driven pulse tube cooler. With i.d.2 mm tube as inertance tube, the tube without reservoir yields close results in terms of lowest temperature to that of the tube with reservoir and both give much better performance than that of an orifice with reservoir. Finally, the advantages of using inertance tube without reservoir are given.     

Test of BaF2 scintillators coupled to a photomultiplier with a CsTe photocathode

Basic properties of BaF₂ scintillators coupled to a photomultiplier with a CsTe photocathode have been investigated. The signal from the photomultiplier shows a drastic reduction of the slow component of the BaF₂ scintillation light while preserving the good properties associated with the fast component.     

Use of a pulsed magnetic field to increase the position sensitivity of a photomultiplier

It is well known that photomultipliers (PMTs) are sensitive to external magnetic fields. We have used this property to vary the gain of the PMT depending on the position of the light source. Various coil configurations have been evaluated to produce local magnetic fields in the region between the photocathode and first dynode to maximize the amplitude variation in the anode signal with respect to change in the coil current. The aim was to improve the position sensitivity of a PMT used in positron emission tomography (PET). The position sensitivity was tested with an array of collimated light emitting diodes directed towards the photocathodes of a Hamamatsu R1548 PMT. The best coil position was above the photocathodes. A 60% reduction in output for light pulses from two LEDs near the coil was obtained with a current of 43 Ampere-turns while signals from two LEDs far from the coil remained the same. The rise time of the magnetic field was 2 μs.     

SENTIRAD—An innovative personal radiation detector based on a scintillation detector and a silicon photomultiplier

The alarming personal radiation detector (PRD) is a device intended for Homeland Security (HLS) applications. This portable device is designed to be worn or carried by security personnel to detect photon-emitting radioactive materials for the purpose of crime prevention. PRD is required to meet the scope of specifications defined by various HLS standards for radiation detection. It is mandatory that the device be sensitive and simultaneously small, pocket-sized, of robust mechanical design and carriable on the user's body. To serve these specialized purposes and requirements, we developed the SENTIRAD, a new radiation detector designed to meet the performance criteria established for counterterrorist applications. SENTIRAD is the first commercially available PRD based on a CsI(Tl) scintillation crystal that is optically coupled with a silicon photomultiplier (SiPM) serving as a light sensor. The rapidly developing technology of SiPM, a multipixel semiconductor photodiode that operates in Geiger mode, has been thoroughly investigated in previous studies. This paper presents the design considerations, constraints and radiological performance relating to the SENTIRAD radiation sensor.