Multianode Photomultiplier Research Articles

Development of a flexible MAPMT photon-counting read-out system

The design and the attained performances of a read-out system for a 64-channel Hamamatsu Multi Anode Photo Multipliers (MAPMT) are discussed. The system has been developed in the framework of the Extreme Universe Space Observatory (EUSO) experiment. EUSO is a space telescope devoted to the study of the ultra-high-energy cosmic rays, proposed for accommodation on board the International Space Station (ISS). This paper reports the tests on the read-out system and the optimization of its main parameters. A quick overview of some other possible applications of the system is also given.

Development of a compact scintillator hodoscope with wavelength-shifting fibre read-out

We report on the prototyping of a plastic scintillator hodoscope with wavelength-shifting fibre read-out by a multi-anode photomultiplier as part of the development of a detector for cosmic-ray muons to be carried aboard an aircraft. Light yield and light attenuation measurements on single- and double-clad wavelength-shifting fibres were performed. Low power, low-threshold, discriminators were designed. A prototype 16-channel hodoscope with two planes was built and tested with cosmic rays. After correcting for geometrical factors a global intrinsic efficiency of ε > 98 % was obtained in both planes. The overall performance of the hodoscope proved it to be well suited for the A dler experiment to measure the high-altitude muon flux.

A scintillating fibre detector for the Crystal Barrel experiment at ELSA

A scintillating fibre detector with high spatial granularity was built for the Crystal Barrel experiment at ELSA (CB-ELSA) in Bonn. It consists of 513 scintillating fibres with 2 mm in diameter, arranged in three layers with cylindrical geometry inside the Crystal Barrel detector surrounding the target cell. Two layers are wound in opposite directions, the third is parallel to the incident beam direction, resulting in an unambiguous hit reconstruction and a position resolution better than 1.6 mm for charged particles. The read-out is done with 16-channel multi-anode photomultipliers. The detector was designed to cover the full angular acceptance of the Crystal Barrel detector with an angular range of 12 ∘ ⩽ θ ⩽ 168 ∘ and 0 ∘ ⩽ φ ⩽ 360 ∘ in the lab frame.

Time-resolved spectrophotometer for turbid media based on supercontinuum generation in a photonic crystal fiber

We describe an instrument for the time-resolved spectroscopy of turbid media that is based on supercontinuum generation in a photonic crystal fiber. The light injected into the sample consists of subpicosecond pulses that cover 550-1000 nm at 85 MHz at an average power of as much as 40 mW. A spectrometer coupled to a multianode photomultiplier tube is used to detect the light simultaneously in 16 wavelength channels, with a resolution of 5-20 nm/channel, depending on the grating. Time-correlated single-photon counting is used to produce time-dispersion curves, which one fits to the diffusion equation to determine absorption and reduced scattering coefficients. We tested the instrument by measuring the time-resolved diffuse reflectance of epoxy phantoms and by performing in vivo measurements on volunteers. The results were similar to those obtained with previous discrete wavelength systems, whereas the full spectrum (610-810 nm) acquisition time was as short as 1 s owing to the parallel acquisition.

“Optical” soft x-ray arrays for fluctuation diagnostics in magnetic fusion energy experiments

We are developing large pixel count, fast (⩾100 kHz) and continuously sampling soft x-ray (SXR) array for the diagnosis of magnetohydrodynamics (MHD) and turbulent fluctuations in magnetic fusion energy plasmas. The arrays are based on efficient scintillators, high thoughput multiclad fiber optics, and multichannel light amplification and integration. Compared to conventional x-ray diode arrays, such systems can provide vastly increased spatial coverage, and access to difficult locations with small neutron noise and damage. An eight-channel array has been built using columnar CsI:Tl as an SXR converter and a multianode photomultiplier tube as photoamplifier. The overall system efficiency is measured using laboratory SXR sources, while the time response and signal-to-noise performance have been evaluated by recording MHD activity from the spherical tori (ST) Current Drive Experiment-Upgrade and National Spherical Torus Experiment, both at Princeton Plasma Physics Laboratory.

Signal processing system based on FPGAs for neutron imaging detectors using scintillators

A signal processing system based on field programmable gate arrays (FPGAs) was developed for a 64 channel×64 channel neutron imaging device using a wavelength shifting fiber read-out based on a photon-counting method. Light signals detected by 64 channel multi-anode photomultipliers are amplified and converted to digital photon signals containing incident-position and time information of neutron by using high-speed amplifiers and discriminators. By using coincidence circuits made in FPGAs, the incident position of neutron is determined based on these digital signals. A neutron imaging detector composed of the signal processing system and a neutron imaging device with a ZnS:Ag/ 6LiF scintillator was evaluated by using neutron beam. It was confirmed that the signal processing based on FPGAs was effective to determine a precise incident position of neutron with high speed and many channel.

Compact high-resolution ion Doppler spectrometer for quartz ultraviolet line emissions

A high-resolution quartz ultraviolet spectrometer based on a single compact 16-channel multianode photomultiplier tube (MAPMT) has been developed and tested on coaxial helicity injection and ohmic transformer current drive plasmas generated on the Helicity Injected Torus at the University of Washington. The use of the compact MAPMT allows a simple design with high light collection and high resolution for an ion Doppler shift diagnostic. The high quality and low cost of the design make it uniquely attractive for university scale plasma experiments. The Doppler shift of impurity ion emission lines from two chords of equal impact parameter but of opposite rotational sense is used to determine chord-averaged toroidal flow velocity. The width of the Doppler broadening is used to calculate the ion temperature. A detailed description of the ion Doppler spectrometer measurement system and some typical results are presented.

Mapping of calf muscle oxygenation and haemoglobin content during dynamic plantar flexion exercise by multi-channel time-resolved near-infrared spectroscopy

A compact and fast multi-channel time-resolved near-infrared spectroscopy system for tissue oximetry was developed. It employs semiconductor laser and fibre optics for delivery of optical signals. Photons are collected by eight 1 mm fibres and detected by a multianode photomultiplier. A time-correlated single photon counting board is used for the parallel acquisition of time-resolved reflectance curves. Estimate of the reduced scattering coefficient is achieved by fitting with a standard model of diffusion theory, while the modified Lambert–Beer law is used to assess the absorption coefficient. In vivo measurements were performed on five healthy volunteers to monitor spatial changes in calf muscle (medial and lateral gastrocnemius; MG, LG) oxygen saturation (SmO2) and total haemoglobin concentration (tHb) during dynamic plantar flexion exercise performed at 50% of the maximal voluntary contraction. At rest SmO2 was 73.0 ± 0.9 and 70.5 ± 1.7% in MG and LG, respectively (P = 0.045). At the end of the exercise, SmO2 decreased (69.1 ± 1.8 and 63.8 ± 2.1% in MG and LG, respectively; P < 0.01). The LG desaturation was greater than the MG desaturation (P < 0.02). These results strengthen the role of time-resolved near-infrared spectroscopy as a powerful tool for investigating the spatial and temporal features of muscle SmO2 and tHb.

Development of hard X-ray polarimeter for $gamma;-ray bursts

The radiation mechanism of gamma-ray bursts (GRBs) is one of the most interesting topics in the field of astrophysics. According to the fireball model, the γ-rays from GRBs should be much polarized. So we have been developing a Compton scattering type hard X-ray polarimeter for GRBs using segmented scintillators and multianode photomultipliers. We carried out basic experiments and computer simulations to investigate the basic performance. As the results, it was recognized that the designed polarimeter can detect the polarization of hard X-rays from GRBs with both the flux 10 times more than that of Crab nebula and the duration of 10 s if the hard X-rays are 8.6% polarized.

Development of hard X-ray polarimeter for γ-ray bursts

The radiation mechanism of gamma-ray bursts (GRBs) is one of the most interesting topics in the field of astrophysics. According to the fireball model, the γ-rays from GRBs should be much polarized. So we have been developing a Compton scattering type hard X-ray polarimeter for GRBs using segmented scintillators and multianode photomultipliers. We carried out basic experiments and computer simulations to investigate the basic performance. As the results, it was recognized that the designed polarimeter can detect the polarization of hard X-rays from GRBs with both the flux 10 times more than that of Crab nebula and the duration of 10 s if the hard X-rays are 8.6% polarized.

A front-end read out chip for the OPERA scintillator tracker

Multi-anode photomultipliers H7546 are used to readout signal from the OPERA Scintillator Tracker (CERN/SPSC 2000-028, SPSC/P318, LNGSP 25/2000; CERN/SPSC 2001-025, SPSC/M668, LNGS-EXP30/2001). A 32-channel front-end Read Out Chip prototype accommodating the H7546 has been designed at LAL. This device features a low-noise, variable gain preamplifier to correct for multi-anode non-uniformity, an auto-trigger capability 100% efficient at a 0.3 photo-electron, and a charge measurement extending over a large dynamic range [0–100] photo-electrons. In this article we describe the ASIC architecture that is being implemented for the Target Tracker in OPERA, with a special emphasis put on the designs and the measured performance.

The HERA-B ring imaging Cherenkov counter

The HERA-B RICH uses a radiation path length of 2.8 m in C 4F 10 gas and a large 24 m 2 spherical mirror for imaging Cherenkov rings. The photon detector consists of 2240 Hamamatsu multi-anode photomultipliers with about 27 000 channels. A 2:1 reducing two-lens telescope in front of each photomultiplier tube increases the sensitive area at the expense of increased pixel size, resulting in a contribution to the resolution which roughly matches that of dispersion. The counter was completed in January of 1999, and its performance has been steady and reliable over the years it has been in operation. The design performance of the Ring Imaging Cherenkov counter was fully reached: the average number of detected photons in the RICH for a β=1 particle was found to be 33 with a single-hit resolution of 0.7 and 1 mrad in the fine and coarse granularity regions, respectively.

MINOS: THE PHYSICS PROGRAM AND THE CONSTRUCTION STATUS

The MINOS experiment will study muon neutrino oscillations in the range of parameter space implied by the measurements with atmospheric neutrinos. The two magnetized toroidal tracking calorimeters, 1 kton at Fermilab and 5.4 kton in the Soudan Mine 735-km away, are constructed out of extruded scintillator strips and use wavelength-shifting and clear fibers read out by multi-anode photomultipliers. The far detector is now more than 3/4 completed and commenced collecting cosmic ray data. The neutrino beamline and the near detector will be finished by the end of 2004. In addition, a calibration detector was also constructed and exposed to the test beams. Over the last two years the entire project has progressed on schedule and budget and with most of the civil construction out of the way the road to this interesting physics program is finally cleared.

Digital front end electronics design for the EUSO photon detector

In this paper we will present the design status of the Digital Front End Electronic system (DFEE), that will be used for the EUSO photon detector. The DFEE is able to count the single photoelectrons coming form the detector for a given time period, store the numbers in a memory buffer and read them out after a trigger, using a serial communication line. Because of space, mass and power consumption constraints, the system will be implemented in an ASIC using a deep submicron technology. The actual design follows the original ideas of the system, though adding several new functionalities. A fully functional prototype chip has been submitted for fabrication in fall 2002. Extensive tests will be performed on it both with bench instrumentations and with the real sensor (the multi anode photomultiplier Hamamatsu R7600-M64), expecting significant results by early Summer 2003. Future work is needed to convert the design into a more robust RAD-hard technology, suitable for space applications and to include in the final die an additional circuit used to optimize the performances at high photons rates: the Analog Front End Electronics (AFEE). Moreover the base board used to house the multi anode photomultipliers is presented: it is the back-bone of the microcell and will be the basic block used to build up the EUSO focal surface.

Multianode photo multiplier tubes as photo detectors for Ring Imaging Cherenkov detectors

The 64-channel Multianode Photo Multiplier (MaPMT) has been evaluated as a candidate for the LHCb Ring Imaging Cherenkov (RICH) photo detectors. We present result from data taken with a 3x3 array of closely packed MaPMTs mounted onto the RICH 1 prototype vessel, exposed to charged particle beams at CERN, and read out at LHC speed. Using a LED light source, we have performed spatial light scans to study the light collection efficiency of the MaPMTs We have also measured the performance of the MaPMTs as a function of the applied high voltage. Different dynode resistor chains have been used to study the tubes at low gains. In addition, we have studied the behaviour of the MaPMT in magnetic fields.

Study of multianode photomultipliers for the electromagnetic calorimeter preshower read out of the lhcb experiment

The Lhcb experiment will study the CP symmetry violation in the system of the beauty particles. The detector is a 20-m-long spectrometer, to be installed on the proton–proton collider Lhc. Of major importance for the level 0 trigger is the preshower of the electromagnetic calorimeter designed to discriminate between electrons, hadrons and photons. The preshower cells consist of a two-radiation-length lead sheet located between two plastic scintillator planes. The scintillation light is extracted with wavelength-shifting fibres. The best candidates to read out the light of the 6000 detector cells are multianode photomultipliers. The HAMAMATSU photomultiplier R5900-00-M64 has been studied and its responses in terms of gain, linearity, uniformity within and between the anodes and cross-talk between the channels are addressed in this document.

Trends in the development of large area photon detectors for Cherenkov light imaging applications

Since the successful operations of hi-tech devices at OMEGA, DELPHI and SLD, the technique of Cherenkov light imaging has gone through an impressive and fruitful evolution driven by the conception of novel large area photon detectors. The well-assessed potentialities of thin CsI films, employed as reflective photoconverters in gas counters operated at atmospheric pressure, will be compared with the promising features of hybrid and multianode vacuum photomultipliers. Recently proposed single-photon gaseous detectors based on GEMs will also be reviewed.

A comparative study of light collector systems for use with multi-anode photo-multipliers

A comparative study of possible Light Collector Systems, designed to increase the geometrical acceptance of commercial Multi-Anode Photo-Multipliers, is presented. A detailed ray tracing study was carried on to evaluate and compare the performance of the different systems, under realistic hypotheses.

Performance of a cluster of multi-anode photomultipliers equipped with lenses for use in a prototype RICH detector

A cluster of multi-anode photomultiplier tubes (MaPMTs) equipped with focusing lenses in front of the tubes was tested in a prototype ring imaging Cherenkov (RICH) detector in a charged particle beam. The readout electronics were capable of capturing the data at 40 MHz. The effects due to charged particles and magnetic field on the MaPMT performance were also studied. The results are used to evaluate the MaPMT as a possible photodetector for the LHCb RICH detectors.

Surface sensitivity of multianode photomultiplier tubes

The sensitivity of three different multianode photomultiplier tubes (Hamamatsu R5900, types M4, M16 and L16) has been measured by scanning a 30 μm diameter light spot across the photocathode surface. For the M16 photomultiplier, the scan has been performed with three different color light sources (blue, green and red LEDs). Also, the response at different incident angles of the light beam has been measured.