Multianode Photomultiplier Research Articles

Four Channel, 40 ps Resolution, Fully Integrated Time-to-Amplitude Converter for Time-Resolved Photon Counting

Recently, a growing interest has arisen about the time-correlated single photon counting (TCSPC) technique, that allows the analysis of fast and weak light waveforms with a time resolution in the picosecond order. Since TCSPC basically consists of the measurement of the arrival time of a photon, a high resolution and high linearity time measurement block is of the utmost importance; moreover, the use of multianode Photo Multiplier Tube and of single photon avalanche diode arrays led to the development of multichannel acquisition systems, where the time measurement block has to be integrated to reduce both cost and area. We have designed and fabricated a four channel fully integrated time-to-amplitude converter (TAC), built in 0.35 μm Si-Ge technology, characterized by an excellent time resolution (less than 50 ps full width half maximum), low differential nonlinearity (better than 0.02 LSB peak-peak and 0.0003 LSB rms), high counting rate (16 MHz), low and constant power dissipation (50 mW) and low area occupation (2.58 × 1.28 mm2 ). Moreover, the very low crosstalk ( -115 dB) between channels, together with low power and low area makes the converter suitable for large scale multi-channel acquisition chains.

Photon Detection Systems for Modern Cherenkov Detectors

Abstract Modern experiments in hadronic physics require detector systems capable of identifying and reconstructing all final–state particle and their momentum vectors. The ANDA experiment at FAIR and the CLAS 12 experiment and Jefferson Laboratory both plan to use imaging Cherenkov counters for particle identification. CLAS 12 will feature a Ring Imaging CHerenkov counter (RICH), while ANDA plans to construct Cherenkov counters relying on the Detections of Internally Reflected Cherenkov light (DIRC). These detectors require high–rate, single–photon capable light detection systems with sufficient granularity and position resolution. Several candidate systems are available, ranging from multi–anode photomultiplier tubes to micro–channel plate systems to silicon photomultipliers. Each of these detection solutions has particular advantages and disadvantages. Detailed studies of the rate dependence, cross–talk, time–resolution and position resolution fro a range of commercially available photon detection solutions are presented and evaluated on their applicability to the ANDA and CLAS12 Cherenkov counters.

SPACIROC: A Front-End Readout ASIC for JEM-EUSO Cosmic Ray Observatory

Abstract The SPACIROC ASIC is designed for the JEM-EUSO fluorescence imaging telescope onboard of the International Space Station. Its goal is the detection of Giant Air Shower above a few 10^19 eV, developing at a distance of about 400 km, downward in the troposphere. From such distance, most of the time, the number of the photons expected in the pixels is very weak, ranging from a few units to a few tens. For such running conditions, we propose a low-power, rad-hard ASIC which is intended for reading out a 64-channel Multi-Anode Photomultiplier. The two main features of this ASIC are the photon counting mode for each input and the charge-to-time (Q-to-T) conversions for the multiplexed channels. In the photon counting mode, the 100% triggering efficiency is achieved for 50 fC input charges. For the Q-to-T converter, the ASIC requires a minimum input of 2 pC. The working conditions of JEM-EUSO require the ASIC to have a low power dissipation which is around 1mW/channel. The design of SPACIROC and the test results are presented in this paper. SPACIROC is a result of the collaboration between OMEGA/LAL-Orsay, France, RIKEN, ISAS/JAXA and Konan University, Japan on behalf of the JEM-EUSO consortium.

Front-end multi-channel PMT-associated readout chip for hodoscope application

For developing a prompt gamma imaging system, we have designed a 16-channel readout chip in a BiCMOS process to be associated with multi-anode photomultipliers (MaPMTs). Each channel has one current input and two separated outputs. The input has very low impedance to minimize electrical crosstalk and effects of capacitances. The two outputs serve to respectively detect signal event and quantify signal charge. The channel architecture is a current-mode one, employing a current conveyor to drive both a buffered current comparator and a charge-sensitive amplifier (CSA). The current conveyor is built with super-common-base (SCB) transistor structures to obtain input impedance in the order of a few ohms. Circuit design with the use of bipolar transistor components also improves frequency and noise performances. The chip has been tested and the evaluated characteristics meet the system requirements.

Progress towards a 256 channel multi-anode microchannel plate photomultiplier system with picosecond timing

Despite the rapid advances in solid state technologies such as the silicon photomultiplier (SiPM), microchannel plate (MCP) photomultipliers still offer a proven and practical technological solution for high channel count pixellated photon-counting systems with very high time resolution. We describe progress towards a 256 channel optical photon-counting system using CERN-developed NINO and HTDC ASICs, and designed primarily for time resolved spectroscopy in life science applications.Having previously built and demonstrated a 18mm diameter prototype tube with an 8×8 channel readout configuration and <43ps rms single photon timing resolution, we are currently developing a 40mm device with a 32×32 channel readout. Initially this will be populated with a 256 channel electronics system comprising four sets of modular 64 channel preamplifier/discriminator, and time-to-digital converter units, arranged in a compact three dimensional configuration.We describe the detector and electronics design and operation, and present performance measurements from the 256 channel development system. We discuss enhancements to the system including higher channel count and the use of application specific on-board signal processing capabilities.

Characterisation and calibration of a scintillating fibre detector with [formula omitted] multi-anode photomultiplier channels

In the Kaosspectrometer at the Mainz Microtron a high-resolution coordinate detector for high-energy particles is operated. It consists of scintillating fibres with diameters of <1mm and is read out by >4000 multi-anode photomultiplier channels. It is one of the most modern focal-plane detectors for magnetic spectrometers world-wide.To correct variations in the detection efficiency, caused by the different gains and the different optical transmittances, a fully automated off-line calibration procedure has been developed. The process includes the positioning of a radioisotope source alongside the detector plane and the automated acquisition and analysis of the detector signals. It was possible to characterise and calibrate each individual fibre channel with a low degree of human interaction.

Multianode photomultiplier tube studies for imaging applications

Highly efficient and position sensitive photon detection is essential in a variety of applications from particle identification in fundamental nuclear and particle physics research, to radionuclide imaging in healthcare. Due to their position sensitivity and high packing fraction, the Hamamatsu H8500 and H9500 multianode photomultiplier tubes (MAPMTs) are promising candidates for such applications and have thus been studied through precision laser scans at several light intensities. This has revealed signal and crosstalk dependencies upon constructional features of the MAPMTs. Both MAPMTs feature a common last dynode output signal, which can be used for self-triggering. The strength and timing of this signal have been investigated for the H8500 MAPMT, yielding similar dependencies upon MAPMT construction and standard deviation time resolutions of 67.5ps and 154.4ps for 20 and single photoelectron signals respectively.

Performance and applications of the UVscope instrument

Abstract UVscope is a portable multi-pixels photon detector developed at IASF-Pa to support experimental activities in the high-energy astrophysics and cosmic rays field. The instrument, working in single photon counting mode, is designed to directly measure light flux in the wavelengths range 300–650 nm. Thanks to its features and operational flexibility, the instrument can be used in a wide field of applications where the knowledge of the environmental luminosity is required, as in the characterization of sites for ground-based Cherenkov and fluorescence telescopes, and for cross-calibration of their cameras. The present version of UVscope is based on a Multi Anode Photo Multiplier Tube and it is completed by a motorized mount and a filter wheel which allow to make low-light measurements, at programmed pointing directions and at different filter wavelengths. In this paper, the instrument is firstly presented in all its components; then the procedures adopted for its absolute and relative calibration are detailed. The performance of UVscope is evaluated and, finally, current and planned scientific applications are described.

A Large-Scale FPGA-Based Trigger and Dead-Time Free DAQ System for the Kaos Spectrometer at MAMI

The Kaos spectrometer is maintained by the A1 collaboration at the Mainz Microtron MAMI with a focus on the study of ( <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">e</i> , <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">e</i> ' <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">K</i> <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">+</sup> ) coincidence reactions. For its electron-arm two vertical planes of fiber arrays, each comprising approximately 10000 fibers, are operated close to zero degree scattering angle and in close proximity to the electron beam. A nearly dead-time free DAQ system to acquire timing and tracking information has been installed for this spectrometer arm. The signals of 144 multianode photomultipliers are collected by 96-channel front-end boards, digitized by double-threshold discriminators and the signal time is picked up by state-of-the-art F1 time-to-digital converter chips. In order to minimize background rates a sophisticated trigger logic was implemented in newly developed Vuprom modules. The trigger performs noise suppression, signal cluster finding, particle tracking and coincidence timing and can be expanded for kinematical matching ( <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">e</i> ' <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">K</i> <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">+</sup> ) coincidences. The full system was designed to process more than 4000 read-out channels and to cope with the high electron flux in the spectrometer and the high count rate requirement of the detectors. It was successfully in-beam tested at MAMI in 2009.

A practical method for depth of interaction determination in monolithic scintillator PET detectors

Several new methods for determining the depth of interaction (DOI) of annihilation photons in monolithic scintillator detectors with single-sided, multi-pixel readout are investigated. The aim is to develop a DOI decoding method that allows for practical implementation in a positron emission tomography system. Specifically, calibration data, obtained with perpendicularly incident gamma photons only, are being used. Furthermore, neither detector modifications nor a priori knowledge of the light transport and/or signal variances is required. For this purpose, a clustering approach is utilized in combination with different parameters correlated with the DOI, such as the degree of similarity to a set of reference light distributions, the measured intensity on the sensor pixel(s) closest to the interaction position and the peak intensity of the measured light distribution. The proposed methods were tested experimentally on a detector comprised of a 20 mm × 20 mm × 12 mm polished LYSO:Ce crystal coupled to a 4 × 4 multi-anode photomultiplier. The method based on the linearly interpolated measured intensities on the sensor pixels closest to the estimated (x, y)-coordinate outperformed the other methods, yielding DOI resolutions between ∼1 and ∼4.5 mm FWHM depending on the DOI, the (x, y) resolution and the amount of reference data used.

The focal surface of the JEM-EUSO instrument

The Extreme Universe Space Observatory on JEM/EF (JEM-EUSO) is a space mission to study extremely high-energy cosmic rays. The JEM-EUSO instrument is a wide-angle refractive telescope in the near-ultraviolet wavelength region which will be mounted to the International Space Station. Its goal is to measure time-resolved fluorescence images of extensive air showers in the atmosphere. In this paper we describe in detail the main features and technological aspects of the focal surface of the instrument. The JEM-EUSO focal surface is a spherically curved surface, with an area of about 4.5 m2. The focal surface detector is made of more than 5000 multi-anode photomultipliers (MAPMTs). Current baseline is Hamamatsu R11265-03-M64. The approach to the focal surface detector is highly modular. Photo-Detector-Modules (PDM) are the basic units that drive the mechanical structure and data acquisition. Each PDM consists of 9 Elementary Cells (ECs). The EC, which is the basic unit of the MAPMT support structure and of the front-end electronics, contains 4 units of MAPMTs. In total, about 1 200 ECs or about 150 PDMs are arranged on the whole of the focal surface of JEM-EUSO.

Development of a CBM-RICH prototype in Pusan

We present the final results from a novel Cherenkov imaging detector called the Focusing DIRC (FDIRC). This detector was designed as a full-scale prototype of the particle identification system for the SuperB experiment [1], and comprises 1/12 of the SuperB barrel azimuthal coverage, with partial photodetector and electronics implementation. The prototype was tested in the SLAC Cosmic Ray Telescope which provided 3D tracking of cosmic muons with an angular resolution of ~1.5 mrad, a position resolution of 4–5 mm, a start time resolution of 70 ps, and muon tracks above ~2 GeV tagged using an iron range stack. The fused silica focusing photon camera was coupled to a full-size BaBar DIRC bar box and was read out, over part of the full coverage, by 12 Hamamatsu H8500 multi-anode photomultipliers (MaPMTs) providing 768 pixels. We used waveform digitizing electronics to read out the MaPMTs. We give a detailed description of our data analysis methods and point out limitations on the present performance. We present results that demonstrate some basic performance characteristics of this design, including (a) single photon Cherenkov angle resolutions with and without chromatic corrections, (b) signal-to-noise (S/N) ratio between the Cherenkov peak and background, which primarily consists of ambiguities of the possible photon paths from emission along the track to a given pixel, (c) dTOP=TOPmeasured – TOPexpected resolutions (with TOP being the photon Time-of-Propagation in fused silica), and (d) performance of the detector in the presence of high-rate backgrounds.

POLAR: A Space-borne X-Ray Polarimeter for Transient Sources

POLAR is a novel compact Compton X-ray polarimeter designed to measure the linear polarization of the prompt emission of Gamma Ray Bursts (GRB) and other strong transient sources such as soft gamma repeaters and solar flares in the energy range 50-500 keV. A detailed measurement of the polarization from astrophysical sources will lead to a better understanding of the source geometry and emission mechanisms. POLAR is expected to observe every year several GRBs with a minimum detectable polarization smaller than 10%, thanks to its large modulation factor, effective area, and field of view. POLAR consists of 1600 low-Z plastic scintillator bars, divided in 25 independent modular units, each read out by one flat-panel multi-anode photomultiplier. The design of POLAR is reviewed, and results of tests of one modular unit of the engineering and qualification model (EQM) of POLAR with synchrotron radiation are presented. After construction and testing of the full EQM, we will start building the flight model in 2011, in view of the launch foreseen in 2013.

Results from first beam tests for the development of a RICH detector for CBM

In the CBM experiment at FAIR, electrons will be identified using a gaseous RICH detector positioned behind a system of silicon tracking stations. The concept of the RICH detector foresees an array of Multianode Photomultipliers (MAPMTs) as photodetector. First beam test data with a 2 GeV proton beam were recorded to investigate the Cherenkov light detection with a 64 channel Hamamatsu H8500 MAPMT. In the beam test a proximity focusing setup with a solid radiator was used together with a new self triggered readout electronics based on the n-XYTER ADC chip. The results of this beam test demonstrate that the new front end electronics is suited for the readout of the Hamamatsu H8500 MAPMT. It could be demonstrated that this MAPMT is able to detect single Cherenkov photons. Uncorrelated noise could be well separated from the signal using available timing information. The recorded number of MAPMT hits per beam event is consistent with the expectations.

A method to localize gamma-ray bursts using POLAR

The hard X-ray polarimeter POLAR aims to measure the linear polarization of the 50–500keV photons arriving from the prompt emission of γ-ray bursts (GRBs). The position in the sky of the detected GRBs is needed to determine their level of polarization. We present here a method by which, despite of the polarimeter incapability of taking images, GRBs can be roughly localized using POLAR alone. For this purpose scalers are attached to the output of the 25 multi-anode photomultipliers (MAPMs) that collect the light from the POLAR scintillator target. Each scaler measures how many GRB photons produce at least one energy deposition above 50keV in the corresponding MAPM. Simulations show that the relative outputs of the 25 scalers depend on the GRB position. A database of very strong GRBs simulated at 10201 positions has been produced. When a GRB is detected, its location is calculated searching the minimum of the χ2 obtained in the comparison between the measured scaler pattern and the database. This GRB localization technique brings enough accuracy so that the error transmitted to the 100% modulation factor is kept below 10% for GRBs with fluence Ftot≥10−5ergcm−2. The POLAR localization capability will be useful for those cases where no other instruments are simultaneously observing the same field of view.

Development of a compact tomography camera system using a multianode photomultiplier tube for compact torus experiments

A compact tomography camera system consisting of a photomultiplier tube, a multislit optical system, and a band-pass interference filter has been developed. The viewing area and spatial resolution can be configured by the arrangement of the slit system. The camera system has been specially designed for self-organized compact torus experiments having strong magnetohydrodynamics events with a submicrosecond time-scale. The developed system has been tested on a field-reversed configuration formed by the field-reversed theta-pinch. Performance evaluation of the system has been performed by comparison to the former optical system.

Development of a compact and high spatial resolution gamma camera system using LaBr3(Ce)

In small animal imaging using a single photon emitting radionuclide, a high spatial resolution gamma camera is required. However, its spatial resolution is limited by the light output of conventional scintillators such as NaI(Tl). We developed and tested a small field-of-view (FOV) gamma camera using a new scintillator, LaBr3(Ce). The LaBr3(Ce) gamma camera consists of a 2mm thick LaBr3(Ce) scintillator, a 2in. 8×8 multi-anode position sensitive photomultiplier tube (Hamamatsu H8500), and a personal computer-based data acquisition system. The LaBr3(Ce) scintillator was directly coupled to the PSPMT and was contained in a hermetically shielded and light tight aluminum case. The signals from the PSPMT were gain corrected, weighted summed, and digitized by 100MHz free running A-D converters in the data acquisition system. The detector part of the gamma camera was encased in a tungsten gamma shield, and a tungsten pinhole collimator was mounted in front of the detector surface. The intrinsic spatial resolution that was measured using a tungsten slit mask was 0.75mm FWHM, and the energy resolution was 8.9% FWHM for 122keV gamma photons. We obtained transmission and emission images that demonstrated the high spatial resolution of the gamma camera system. Approximately two years after the fabrication of the detector, the flood image showed significant distortion due to the change in LaBr3(Ce) of its hygroscopic characteristic. These results confirm that the developed LaBr3(Ce) gamma camera is promising for small animal imaging using a low energy single photon emitting radionuclide if the hygroscopic problem of LaBr3(Ce) will be solved.

Positron emission mammography using Pr:LuAG scintillator – Fusion of optical material study and systems engineering

The breast cancer is one of the most frequent cause of death among female cancer patients. However, when discovered at the early stage, the probability of recovery is very high. Therefore, the development of positron emission mammography (PEM) to detect the breast cancer at the early stage with high efficiency is demanding. As the diameter of the scanner part is small, a scintillator with faster response is required. As the recently developed Pr:LuAG has almost twice as short scintillation decay time than that of Ce:LSO, the Pr:LuAG scintillator was employed in our recently developed PEM system. One camera unit consisted of 20 × 64 scintillator pixels optically coupled with three H8500-03 multi anode photomultipliers. The Pr:LuAG pixel size is 2.1 × 2.1 × 15 mm 3 and the BaSO 4 was used as a reflector. Four planar cameras are placed at both sides. Therefore, eight cameras were installed at both sides of the instrument. The spatial resolution was evaluated to be 1.1 mm using the 22Na point source. Fluorodeoxyglucose with 18F hotspot image was also detected using the breast phantom.

Scintillating anticoincidence detection elements design and tests with muons and protons

Design, construction and tests of anticoincidence detection elements are presented. Initially planned to be used as active shielding parts of the anticoincidence detector of the Simbol-X mission, they are aimed to detect cosmic protons and provide veto signal against charged-particle background induced on imaging detectors. The sample is made of a scintillator plate into which grooves are machined and waveshifting fibers glued. The fibers are connected to multianode photomultiplier (PM) tubes. The tubes characteristics have been evaluated for this application. The device has been tested with atmospheric muons that deposit similar energy to that of cosmic protons thanks to a specially designed muon telescope also described in this paper. Tests have also been performed with protons of a tandem accelerator beam line. The response is on average above 10 photoelectrons, which is not complicated to detect, which allows very good detection efficiency as well as very good ability to reject noise. In addition many evolution and performance improvements appear possible.

The data acquisition and handling system of JEM-EUSO experiment

In this work we discuss the Data Handling electronics of the JEM-EUSO experiment, devoted to the study of UHE Cosmic Rays from space. The detector is composed of about 6000 multianode photomultipliers for a total of ≃2×105 channels. A multi-layer parallel architecture has been devised to handle the data flow and select valid triggers, reducing it to a rate compatible with downlink constraints. Each processing level filters the event with increasingly complex algorithms using ASIC, FPGAs and DSPs in this order to reject spurious events and reduce the data rate. The main CPU monitors the general acquisition of the experiment, handles the slow control and the interfaces to the Space Station. In this work are discussed the hardware solutions adopted to cope with the various constraints posed by this space borne detector.