Micropixel Avalanche Photodiodes Research Articles

Development of compact radiation detectors based on MAPD photodiodeswith Lutetium Fine Silicate and stilbene scintillators

Results of gamma-ray measurements taken with Lutetium Fine Silicate (LFS) scintillators and Micro-Pixel Avalanche Photodiodes (MAPD) are presented in the energy range of 59.6 keV to 834.8 keV . Dependences of energy resolution on gamma-ray energy are studied. Results of several measurements are discussed to assess the performance of gamma ray source identification of the developed detector. The alpha particle and neutron detection performance of LFS and stilbene scintillators coupled to micro-pixel avalanche photodiode are discussed as well.

The design of a module of a new electromagnetic calorimeter for COMPASS II

A new-generation high-granularity Shashlyk EM calorimeter read out by micropixel avalanche photodiodes with thermostabilization based on the Peltier element is designed and constructed.

Alpha particle detector based on micropixel avalanche photodiodes

The main goal of this work is to study the possibility of detecting alpha particles with a micropixel avalanche photodiode (MAPD) in combination with Lutetium Fine Silicate (LFS) scintillators (500 μm thick). The results show that alpha detectors based on the MAPD are expected to be useful in many applications: public security (associated particle imaging for explosives and drugs detection), radioactive contamination monitoring in various environments, and detection of charged particles from nuclear reactions.

Technology of manufacturing micropixel avalanche photodiodes and a compact matrix on their basis

A technology for manufacturing a new micropixel avalanche photodiode (MAPD) with deeply buried pixels (including two epitaxial layers between which an array of n +) regions is formed by ionic doping) is described. A new method for manufacturing the compact MAPD matrices with minimum dead zone is proposed.

Shashlyk EM calorimeter prototype readout by MAPD with superhigh pixel density for COMPASS II

The new-generation high-granularity Shashlyk EM calorimeter readout by micropixel avalanche photodiodes (MAPD) with precision thermostabilization based on the Peltier element is designed, constructed end tested. MAPD-3N with superhigh pixel density 1.5×104mm−2 and area 3×3mm2 manufactured by the Zecotek Company were used in the photodetector unit.

Micropixel avalanche photodiodes and the possibility for their application in positron-emission tomography

Micropixel avalanche photodiodes (MAPDs) are new instruments for detecting low-intensity light. They consist of many microcounters (pixels integrated on a common silicon wafer). A unique design by the Joint Institute for Nuclear Research (JINR) (Z. Sadygov)—deep-microwell MAPD—provides an order of larger pixel densities without losses in photon-detection efficiency. These instruments are beginning to find use in precision electromagnetic calorimetry. MAPDs can be most widely applied as photodetectors in scanners for positron-emission tomographs (PETs), particularly the time-of-flight PETs becoming popular now. The possibility of using MAPDs in PETs is shown, and the time resolution of a pair of quanta detected by Lutetium Fine Silicate scintillation crystals with MAPD readout is obtained at the level of 400 ps.

Development of radiation medicine at DLNP, JINR

The Dzhelepov Laboratory of Nuclear Problems’ activity is aimed at developing three directions in radiation medicine: 3D conformal proton therapy, accelerator techniques for proton and carbon treatment of tumors, and new types of detector systems for spectrometric computed tomography (CT) and positron emission tomography (PET). JINR and IBA have developed and constructed the medical proton cyclotron C235-V3. At present, all basic cyclotron systems have been built. We plan to assemble this cyclotron at JINR in 2011 and perform tests with the extracted proton beam in 2012. A superconducting isochronous cyclotron C400 has been designed by the IBA-JINR collaboration. This cyclotron will be used for radiotherapy with proton, helium and carbon ions. The 12C6+ and 4He2+ ions will be accelerated to an energy of 400 MeV/amu, the protons will be extracted at the energy 265 MeV. The construction of the C400 cyclotron was started in 2010 within the framework of the Archarde project (France). Development of spectrometric CT tomographs may allow one to determine the chemical composition of a substance together with the density, measured using traditional CT. This may advance modern diagnostic methods significantly. JINR develops fundamentally new pixel detector systems for spectrometric CT. The time-of-flight (TOF) system installed in the positron emission tomograph (PET) permits essential reduction in the detector noise from occasional events of different positron annihilations. The micropixel avalanche photodiodes (MAPDs) developed at JINR allow a factor of 1.5 reduction in the resolution time for the PET TOF system and suppression of the noise level as compared to commercial PET. The development of a combined PET/MRI is of considerable medical interest, but it cannot be made with the existing PET tomographs based on detectors of compact photomultipliers due to strong alternating magnetic field of MRI. Change-over to detectors of micropixel avalanche photodiodes permits making a combined PET/MRI.

Novel micropixel avalanche photodiodes (MAPD) with super high pixel density

In many detectors based on scintillators the photomultiplier tubes (PMTs) are used as photodetectors. At present photodiodes are finding wide application. Solid state photodetectors allow operation in strong magnetic fields that are often present in applications, e.g. some calorimeters operating near magnets, combined PET and MRT, etc. The photon detection efficiency (PDE) of photodiodes may reach values a few times higher than that of PMTs. Also, they are rigid, compact and have relatively low operating voltage. In the last few years Micropixel Avalanche PhotoDiodes (MAPD) have been developed and started to be used. The MAPD combines a lot of advantages of semiconductor photodetectors and has a high gain, which is close to that of the PMT. Yet, they have some disadvantages, and one of them is a limited dynamic range that corresponds to a total number of pixels. The novel deep microwell MAPD with high pixel density produced by the Zecotek Company partially avoids this disadvantage. In this paper characteristics of these photodetectors are presented in comparison with the PMT characteristics. The results refer to measurements of the gain, PDE, cross-talks, photon counting and applications: beam test results of two different “Shashlyk” EM calorimeters for COMPASS (CERN) and NICA-MPD (JINR) with the MAPD readout and a possibility of using the MAPD in PET.

Beam test of Shashlyk EM calorimeter prototypes readout by novel MAPD with super high linearity

The main properties of two different Shashlyk EM calorimeter modules readout by novel micropixel avalanche photodiodes (MAPD) with microwell structure and very high density of pixels were studied at the T9 CERN PS test-beam facility. A MAPD-3A with density of pixels 1.5×10 4 mm −2 and area 3×3 mm 2 manufactured by Zecotek Company was used in our test.

Statistical LOR estimation for a high-resolution dMiCE PET detector

We develop a statistical line of response (LOR) estimator of the three-dimensional interaction positions of a pair of annihilation photons in a PET detector module with depth of interaction capability. The three-dimensional points of interaction of a coincidence pair of photons within the detector module are estimated by calculation of an expectation of the points of interaction conditioned on the signals measured by the photosensors. This conditional expectation is computed from estimates of the probability density function of the light collection process and a model of the kinetics of photon interactions in the detector module. Our algorithm is capable of handling coincidences where each annihilation photon interacts any number of times within the detector module before being completely absorbed or escaping. In the case of multiple interactions, our algorithm estimates the position of the first interaction for each of the coincidence photons. This LOR estimation algorithm is developed for a high-resolution PET detector capable of providing depth-of-interaction information. Depth of interaction is measured by tailoring the light shared between two adjacent detector elements. These light-sharing crystal pairs are referred to as dMiCE and are being developed in our lab. Each detector element in the prototype system has a 2 × 2 mm2 cross section and is directly coupled to a micro-pixel avalanche photodiode (MAPD). In this set-up, the distribution of the ratio of light shared between two adjacent detector elements can be expressed as a function of the depth of interaction. Monte Carlo experiments are performed using our LOR estimation algorithm and compared with Anger logic. We show that our LOR estimation algorithm provides a significant improvement over Anger logic under a variety of parameters.

Spatial distribution of photo-sensitivity in new micro-pixel avalanche photodiodes: Assembly of 64-element arrays

A 64-element array was assembled out of 3×3-mm 2 Micro-pixel Avalanche Photodiodes (MAPD) for use in the next-generation PET scanners. Spatial distribution of photo-response across the surface of a single element as well as bias voltage variation between elements of the array was studied.

Use of micro-pixel avalanche photodiodes for the readout of a lead/scintillator hadron calorimeter

The application of micro-pixel Avalanche photodiodes (MAPD) for the readout of hadron calorimeters is discussed. A prototype calorimeter was constructed consisting of individual lead/scintillator sandwich modules with a sampling satisfying the compensating condition. The light from each scintillator tile is captured and transported with WLS fibers embedded in the scintillator and extended to the rear end of the module. A set of 6 WLS fibers from neighboring tiles is grouped in one bundle and viewed by a 3×3 mm 2 avalanche micro-pixel photodiode. The design provides a longitudinal segmentation of the module into 10 sections with independent MAPD readout. Use of MAPDs with pixel density 10 4/mm 2 ensures good linearity of calorimeter response over a wide dynamical range. The performance of the calorimeter prototype in beam tests is reported.

Performance of new Micro-pixel Avalanche Photodiodes from Zecotek Photonics

Two new types of Micro-pixel Avalanche Photodiodes (MAPD) with sensitive area 3×3 mm 2 and pixel densities of 15 000 and 40 000/mm 2, respectively, were designed and produced by Zecotek Photonics, Inc. Design and operation principles of these devices are described in this work. Measurement results of basic parameters are given as well.

Highly sensitive micropixel avalanche photodiodes for scintillation counters of the T2K neutrino experiment

Highly sensitive micropixel avalanche photodiodes with a metal-resistor-semiconductor structure (MRS APDs) operating in the restricted Geiger discharge mode and scintillation detectors with wavelength-shifting optical fibers developed for the T2K neutrino oscillation experiment have been investigated. Dependencies of basic MRS APD parameters on the bias voltage, photon wavelength, and temperature have been measured. Characteristics of the scintillation detectors with wavelength-shifting optical fibers and avalanche photodiodes are described.

Test of micropixel avalanche photodiodes

The micropixel avalanche photodiode (MAPD) is a novel photodetector with a multipixel intrinsic structure on the common silicon substrate. The typical size of each pixel is 20–30 μm and the density is about 10 3 mm −2. Each pixel works on the common load in the Geiger mode, where the discharge is limited by an individual quenching resistor (negative feedback like in gas Geiger counter) included in each pixel feeding chain located on the common substrate. In the Geiger mode one may get an amplification factor for a single photoelectron at the level of 10 6 at room temperature. Measurements of gain, photon detection efficiency, one photoelectron resolution, noise and dark current for different types of MAPD were performed and compared.

Three advanced designs of micro-pixel avalanche photodiodes: Their present status, maximum possibilities and limitations

Novel types of micro-pixel avalanche photodiodes (MAPDs) and their principle of performance are analyzed. The first design contains a common silicon wafer on which a matrix of independent p–n junctions (micro-pixels) with individual surface resistors are created. The individual resistors provide a local suppression of the avalanche process and discharge each micro-pixel to a common metal grid (electrode). The second design is an avalanche photodiode with independent micro-pixels in which the local suppression of the avalanche process is carried out due to the limited conductivity of individual surface drift channels formed along the silicon–silicon oxide boundary. This design is considered as a prototype for a future super-fast avalanche CCD matrix capable to work in a single-photon detection mode. The third design contains a matrix of deep buried multilayer pixels with an individual suppression of the avalanche process in independent vertical channels.